Content:

HS – Hydrological Sciences

HS1.1.1 – The MacGyver session for innovative and/or self made tools to observe the geosphere

EGU2020-8316 | Displays | HS1.1.1

How to circumvent the limitations of open source software and orthorectify how (or better) than with commercial software

Valerio Baiocchi, Roberta Onori, Felicia Monti, and Francesca Giannone

High and very high resolution satellite images are now an irreplaceable resource for earth observation in general and for the extraction of hydrogeological information in particular. In order to use them correctly and compare them with previous surveys and maps, they must be treated geometrically to remove the distortions introduced by the acquisition process. Orthorectification is not a simple georeferencing because the process must take into account the three-dimensional acquisition geometry of the sensor. For this reason orthorectification must be performed within specific commercial software with additional costs compared to image acquisition which, in some cases, is currently free of charge.
Some orthorectification algorithms, mainly based on the RPC approach, are available in open source GIS software such as QGIS. OTB (Orpheus toolbox) for QGIS contains some of these algorithms but its interfaces are not clear and there are some incomprehensible limitations such as the impossibility to input three-dimensional ground control points (GCPs). This severely limits the final achievable accuracy because it does not allow to correctly estimate the influence of different ground morphologies on the acquisition geometry. To get around these limitations you can make a "pseudo DEM" and other expedients to complete the whole process obtaining absolute results comparable if not better than those of commercial software.
The proposed procedure may not be the fastest but it can be a valid alternative for those who use satellite images as a tool in their research work.

 

How to cite: Baiocchi, V., Onori, R., Monti, F., and Giannone, F.: How to circumvent the limitations of open source software and orthorectify how (or better) than with commercial software, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-8316, https://doi.org/10.5194/egusphere-egu2020-8316, 2020.

The conservation and long-term protection of our environment require a better understanding of ecosystems through cross-domain integration of data and knowledge from different disciplines. Current methods used in applied environmental research and scientific surveys are not sufficient to address the heterogeneity and dynamics of ecosystems appropriately. To this end, an urgent need is seen in introducing new technology and methods for a service-oriented and holistic in-situ monitoring with increased spatio-temporal resolution and cutting edge functionalities. Recent developments in the field of digital information processing, the internet of things (IoT) or the the analysis of complex datasets are opening up new possibilities for data-based environmental research. This rapidly developing fields are calling for a disruptive paradigm shift towards a service-oriented earth observation (smart monitoring). To this end, future earth observation approaches will have a much stronger coupling between the modeling and the data acquisition. The development, implementation and evaluation of such an interface is one of the overall objectives of this project. To achieve this goal, a basic data model and a special hardware architecture must be defined. A realistic application scenario will be used to demonstrate the advantages of developing a monitoring strategy that is no longer based on static data collection but on the coupling of modeling and empiricism using integrated sensors for an advanced modeling. Since current methods have so far failed to allow a holistic assessment of varying, large-scale environmental phenomena there is a corresponding need for capable hardware which is specialized for exactly this purpose.

The project aims to introduce an integrated sensor system for advanced modeling of turbidity and dissolved organic matter using miniaturized optical sensors in the ultraviolett and infrared range. Moreover, a data-driven, open-source architecture for service-oriented observation methods and in-stream process modeling close to real-time was developed. In addition to the hardware-related requirements of such a sensor system, the creation of an interface between the physical environment (sensor level) or abstracted model assumption (model level) is a particular focus of the research project. A sampling theorem, the predictive object specific exposure (POSE), is introduced as an underlying measurement paradigm and data model. This allows to consider not only the measured value in the evaluation but also accompanied parameters, which is called the context of a measurement. The development and provision of a first adaptive sensor concept resulted in promising prototype enabling the possibility to record environmental data depending on decision criteria such as location, time or context. Thus, the project is representing an interesting practical contribution to Digital Earth.

How to cite: Wagner, R. and Goblirsch, T.: A data-driven open-source architecture for service-oriented observation methods and in-stream process modeling of turbidity and dissolved organic matter, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-21587, https://doi.org/10.5194/egusphere-egu2020-21587, 2020.

EGU2020-6102 | Displays | HS1.1.1

DIY approach to measuring surface water properties in the estuary

Vladimir Divić, Morena Galešić, Mariaines Di Dato, Marina Tavra, and Roko Andričević

The monitoring of water bodies, specifically complex ones such as estuaries, has been historically limited. Various research efforts were hindered due to the gaps in the technology implementation and accompanied by the price of developed solutions (usually as a black box for the end-user). However, thanks to the growing trend of open source solutions both in hardware and software domain, it has become more available to apply the DIY (do it yourself) approach and build the equipment that one might need. As all frugal innovations tend to emerge from a problem that had an existing commercial solution but was too demanding on resources, the floating measurement system presented in this study was designed to get surface water properties simultaneously in multiple points. Using multiple commercial probes to do such measurements was too expensive. Therefore, we have developed an innovative low-cost drifter based on the Arduino platform as an alternative. Our device is designed to measure position, temperature, and electrical conductivity in multiple drifter realisations or short-term moored measurements. The system consists of a floating container equipped with the following components: an Arduino Mega development board, a power management module, an SD card logging module, a Bluetooth module, a temperature measuring module, a global positioning satellite (GPS) position module, and a newly developed module for measuring electrical conductivity (EC). The applicability was tested at the estuary of River Jadro near Split (Croatia) and obtained spatial data (velocity, temperature, electrical conductivity and salinity) was analysed and compared with analytical models. All used tools are open-source and greatly supported by the worldwide community. Furthermore, we consider this prototype to be one of the first steps toward development of various DIY monitoring systems with a potential for a broader range of applications. We present our work with a purpose to initiate a dialogue with more collaborators interested in developing different variations of custom-built sensors for water properties.

How to cite: Divić, V., Galešić, M., Di Dato, M., Tavra, M., and Andričević, R.: DIY approach to measuring surface water properties in the estuary, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-6102, https://doi.org/10.5194/egusphere-egu2020-6102, 2020.

EGU2020-20175 | Displays | HS1.1.1

Low Cost Sensor Node for Monitoring River Floods

Evangelos Skoubris and George Hloupis

River floods occupy a respectable percentage among all natural disasters, are presenting high risk, and usually cause great damage. Important tools in managing and preventing river floods are the Early Warning Systems (EWS), which are usually consisted both by a hardware infrastructure (sensors, communication network) and a relevant software infrastructure (data logging, signal processing, modeling, risk detection).

In the current work we are presenting preliminary results from a novel, low-cost and low-power hardware system, part of a EWS aimed for river floods. The system consists of multiple sensing nodes, each to be strategically positioned at certain points along the route of river Evros, Greece. Each sensing node will bear a low-cost and high-quality ultrasonic water level sensor, along with an embedded microcomputer to control its functionality. An additional novelty of the proposed work is the design and utilization of a private low-power wide-area wireless network (LPWAN), taking advantage of IoT technologies and especially the LoRaWAN implementation. This way, the proposed system will have even lower power demands, together with greater expandability by allowing many nodes to be simultaneously connected and measuring, and having the ability to utilize crowd-sensing techniques. The power supply is battery based and autonomously recharged with the aid of small solar panel. Each node will measure the water level of the river, and upload the data to a cloud server at variable time intervals, depending on the actual water level variation and the system’s power consumption optimization.

Future upgrades of the system will involve extra sensors, allowing the nodes to measure water quality parameters i.e. suspended solids, pH, etc. Although of secondary importance, these parameters might prove to be important in the development of the risk detection and alarm issuing algorithms.

How to cite: Skoubris, E. and Hloupis, G.: Low Cost Sensor Node for Monitoring River Floods, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-20175, https://doi.org/10.5194/egusphere-egu2020-20175, 2020.

EGU2020-83 | Displays | HS1.1.1

Multipurpose IoT network watchdog device with capability of add on sensors for multi instrument field stations.

Panagiotis Argyrakis, Theodore Chinis, Alexandra Moshou, and Nikolaos Sagias

Several stations (seismological, geodetical, etc.) suffer from communications problems, such problems create data gaps in real-time data transmission, also excess humidity and temperatures further than manufacturer limits, usually make components and circuitry, of expensive instruments, failure, and results to unaffordable service or unrepairable damage.

We create a low-cost opensource device that will raise the reliability of the stations and secure the instruments from severe damage, such a device installed as prototype at UOA (University of Athens) seismological station KARY (Karistos Greece) for a year and the reliability of the station raised tremendously, since then the device upgraded to provide wireless connection and IoT GUI (mobile app). A local server was built to serve all the devices uninterrupted and provide a secured network.

The software is fully customizable and multiple inputs can provide addon sensors capability, for example, gas sensor, humidity sensor, etc., all the data are collected to a remote database for real-time visualization and archiving for further analysis.

The shell which covers the circuitry is 3D-printed with a high temperature and humidity-resistant material and it’s also fully customizable by the user. 

How to cite: Argyrakis, P., Chinis, T., Moshou, A., and Sagias, N.: Multipurpose IoT network watchdog device with capability of add on sensors for multi instrument field stations., EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-83, https://doi.org/10.5194/egusphere-egu2020-83, 2020.

The collective term ‘Internet of Things’ (IoT) encompasses a variety of technologies and methods providing novel opportunities for data acquisition and control in environmental sciences. Availability of cost effective components as well as support of large open source communities allow scientists to gain more flexibility and control over their experimental setups. However quality of measurements, stability of instruments as well as real costs for development and maintenance are often underestimated challenges. The presentation introduces current best practices of IoT principles in scientific applications. Examples of low cost sensors, low power electronics, wireless data transmission protocols, time series databases as well as real-time visualization are presented and discussed. Furthermore light is shed on non-technological issues of the ‘do-it-yourself’ or ‘maker’ approach such as social and psychological aspects. The ‘make-share-learn’ paradigm of the maker culture can be utilized to raise awareness. It provides significant opportunities for environmental education and community building which constantly gain more importance in the context of climate and environmental change.

How to cite: Becker, R.: ‘Internet of Things’ for environmental sciences and education, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-19810, https://doi.org/10.5194/egusphere-egu2020-19810, 2020.

EGU2020-3032 | Displays | HS1.1.1

Microcontrollers beyond Arduino: a stationary and a mobile environmental monitoring system

Daniel Beiter, Tobias Vetter, Markus Morgner, Carlo Seehaus, Stephan Schröder, and Theresa Blume

In the course of the Helmholtz MOSES initiative two monitoring systems are being developed which consist of the same key components and thus functionality but with very different scopes of application. One is a stationary data logger with a classic measurement routine (on/off duty cycle) and support for various hardware interfaces (2xSDI12, 1xRS485, 2xUART, amongst others). The other is a drifting data logger that stays idle until a flood event activates the logger and carries it downstream. On-board are turbidity, EC and temperature sensors, a GPS and an inertial measurement unit (IMU) monitoring turbulence.

Advancements in electronics driven by automotive, mobile and IoT applications led to the development of very powerful, small and low power microcontrollers. This is why we decided to leave the realms of ATMega 8-bit systems (such as Arduino) and move towards ARM Cortex 32-bit systems. More precisely we used the Teensy 3.5 microcontroller development system as the core for the two systems. It is superior to Arduino in terms of performance while its developing team tries to maintain compatibility to Arduino in terms of programming vocabulary. This allows easier migration but comes also with restrictions regarding the capabilities of the hardware.
The other key component is the FiPy which supports five different wireless network types (WiFi, Bluetooth, LoRa, Sigfox, LTE-M) in one module. In comparison to most other hardware it runs MicroPython which adds more complexity to the project. Even though it is a microcontroller and features also several hardware interfaces, power consumption is far from low power, which is why it is used here only for remote communication and data transmission. In addition, several design decisions were made regarding power path routing and jumper configuration to improve the systems’ overall versatility, debugging capabilities and low power functionality, which are often key to the feasibility of a remote monitoring system.

How to cite: Beiter, D., Vetter, T., Morgner, M., Seehaus, C., Schröder, S., and Blume, T.: Microcontrollers beyond Arduino: a stationary and a mobile environmental monitoring system, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-3032, https://doi.org/10.5194/egusphere-egu2020-3032, 2020.

EGU2020-18989 | Displays | HS1.1.1 | Highlight

A high capacity, automatic and small-volume water sampler

Núria Martínez-Carreras, François Barnich, Jean François Iffly, Oliver O'Nagy, and Andrei Popleteev

Field deployable and portable automatic water samplers are common tools in hydrology. They allow the unattended collection of water samples at predetermined times or triggered by external sensors, reducing personnel labour and costs. Several automated water samplers have been described in the literature. However, the vast majority of these samplers are not commercialised and their use is very limited or restricted to research applications. We can broadly classify these samplers in three groups: in situ samplers, sequential precipitation samplers and siphon automatic samplers. The latest are commonly used by hydrologists, environmental monitoring agencies and in wastewater treatment plants. They were first patented and commercialized in the 1980s by Teledyne-ISCO (Lincoln, NE, USA). They use a peristaltic pump to transfer water into several containers. However, the siphon automatic samplers are large, heavy and typically collect a maximum of 24 samples of 0.5 or 1 L. Here, we present a new automatic water sampler that has a larger and variable storage capacity (from 64 to 400) of smaller containers (from 2 to 40 mL). We argue that for many applications large sample volumes are no longer required due to the improvement of chemical analytic techniques. Standard laboratory storage boxes are filled with standard laboratory containers and directly placed inside the sampler, reducing the processing time once the samplers are back in the laboratory. Containers remain always closed with a septum cap to prevent evaporation. The sampler allows tub rinsing between sample collection to prevent contamination and memory effects. It is portable, has a low-power consumption and is robust for its use under field conditions. We tested the prototype in the laboratory and in the field. We will present the sampler mechanical functioning, the results of the tests (e.g. sample preservation and memory effects) and the user-friendly interface to define sampling schemes.

How to cite: Martínez-Carreras, N., Barnich, F., Iffly, J. F., O'Nagy, O., and Popleteev, A.: A high capacity, automatic and small-volume water sampler, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-18989, https://doi.org/10.5194/egusphere-egu2020-18989, 2020.

EGU2020-13711 | Displays | HS1.1.1

Automated high resolution rain water sampler for stable water isotope monitoring

Christoff Andermann, Torsten Queißer, Markus Reich, Bijaya Puri, Niels Hovius, and Dirk Sachse

With global climate change, one of the largest short-term threats to our societies comes from changes in the hydro-meteorological cycle: droughts, flooding and potentially increasing extreme rain events may have far greater direct impact on humans than rising temperatures alone. These changes often have sever consequences and widespread impact on society and ecosystems, yet they are difficult to track, trace and measure in order to fully understand the underlying process of delivering moisture and recharging water reservoirs. Only through the comprehensive monitoring of precipitation waters in space and time can we improve our process understanding and better predict the direction and magnitude of future hydro-meteorological changes, in particular on regional spatial scales. However, no commercial automated sampling solution exists, which fulfills the quality criteria for sophisticated hydrochemical water analysis. Here, we present an advanced prototype automatic precipitation water sampler for stable water isotope analysis of precipitation. The device is designed to be highly autonomous and robust for campaign deployment in harsh remote areas and fulfills the high demands on sampling and storage for isotope analysis (i.e. sealing of samples from atmospheric influences, no contamination and preservation of the sample material). The sampling device is portable, has low power consumption and a real-time adaptable sampling protocol strategy, and can be maintained at distance without any need to visit the location. Furthermore, the obtained water samples are not restricted to isotope analysis but can be used for any type of environmental water analysis. The current configuration can obtain 165 discrete rainwater samples with a minimum timely resolution of 5min or volume wise 2mm of rainfall. Our lab tests with dyed waters and waters with strongly differing isotopic signature demonstrate that the device can obtain, store and conserve samples without cross contamination over long periods of time. The device has been tested so far under several conditions, e.g. heavy summer thunderstorms with more than 50mm/24h of rainfall, sustained winter rainfall and in cold conditions involving melting of snow. This automated rainwater sampler provides an economic and sophisticated technological solution for monitoring moisture pathways and water transfer processes with the analytical quality of laboratory standard measurements on a new level of temporal and spatial resolution.

How to cite: Andermann, C., Queißer, T., Reich, M., Puri, B., Hovius, N., and Sachse, D.: Automated high resolution rain water sampler for stable water isotope monitoring , EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-13711, https://doi.org/10.5194/egusphere-egu2020-13711, 2020.

EGU2020-3141 | Displays | HS1.1.1 | Highlight

Developing an Autonomous Hovercraft for Benthic Surveying in Very Shallow Waters

Meghan Troup, David Barclay, and Matthew Hatcher

Benthic surveys in very shallow water (< 1 meter) are often carried out by remote sensing methods such as LiDAR, satellite imagery, and aerial photography, or by written observations paired with GPS point measurements and underwater video. Remote sensing can be helpful for large scale mapping endeavors, but the optical methods commonly used are limited in their effectiveness by cloud cover and water clarity. In situ surveys are often carried out manually and can therefore be quite inefficient. A proposed alternative method of small scale, high resolution mapping is an autonomous, amphibious hovercraft, fitted with high frequency single-beam and side-scan sonar instruments. A hovercraft can move seamlessly from land to water which allows for convenient and simple deployment. The sonar instruments are attached to a boat-shaped outrigger hull that can be raised and lowered automatically, enabling data collection in water as shallow as 10 cm. These data are used to extract seafloor characteristics in order to create detailed maps of the research area that include information such as sediment type, presence and extent of flora and fauna, and small-scale bathymetry.

How to cite: Troup, M., Barclay, D., and Hatcher, M.: Developing an Autonomous Hovercraft for Benthic Surveying in Very Shallow Waters, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-3141, https://doi.org/10.5194/egusphere-egu2020-3141, 2020.

EGU2020-10190 * | Displays | HS1.1.1 | Highlight

Democratizing ocean technology: low-cost innovations in underwater robotics

Allison Chua, Aaron MacNeill, and Douglas Wallace

In comparison to the ocean’s immense volume and diversity of research areas, the number of sensors required to make the majority of desired measurements is quite small. This inequality of supply and demand elevates prices, adding further barriers for developing nations or fledgling research programs with smaller budgets attempting ocean science. Our work aims to demonstrate the potential of combining commercially available, open-source products to create inexpensive, configurable, and user-friendly platforms that can be adapted for underwater navigation and integration with most commercial oceanographic sensors.

Specifically, we will highlight modifications made to a Blue Robotics BlueROV2, which we have configured for various missions including vertical profiling of a coastal fjord and three-dimensional mapping of crude oil spills. The BlueROV2 offers an easily modified platform for physical mounting of sensors and streaming of sensor data via its onboard computer, a Raspberry Pi. Our custom circuit board is “sensor-agnostic”, powering sensors from a common source (the ROV battery) and using an Arduino that accepts analog or digital sensor inputs, allowing us to choose from a wide range of sensors. Physical modifications make use of inexpensive, readily available materials, and range from simple plastic brackets for small sensors to a skid for a sensor with half the ROV’s original weight, which utilizes pop bottles for buoyancy.

While products such as Pixhawk, Raspberry Pi, Arduino, and BlueROV have inspired hobbyists and youth around the world, they paradoxically have not been as widely embraced in the academic community, who perhaps remain unaware of their research potential. Thus, while there has yet to be an analogous push to develop inexpensive, small, power-efficient, and open-source sensors, these platforms offer exciting opportunities to build a new generation of oceanographic tools with measurement abilities far exceeding those of their predecessors. We are at an ocean technology tipping point, and, as MacGyver says, “With a little bit of imagination, anything is possible.”

How to cite: Chua, A., MacNeill, A., and Wallace, D.: Democratizing ocean technology: low-cost innovations in underwater robotics, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-10190, https://doi.org/10.5194/egusphere-egu2020-10190, 2020.

EGU2020-4291 | Displays | HS1.1.1

Open-source surface watercraft for Riverscape mapping

James Dietrich, Mark Fonstad, and Aaron Zettler-Mann

Most river system analyses use either intensive, small-area surveys, or extensive, low-resolution surveys. Recent research trends have shown that both high-resolution and river-extent information are necessary to understand fundamental questions of river processes including patterns of critical habitat, sediment links, and river instability. As part of a larger NSF-funded research project, we have developed an open-source, boat-based mapping approach to measure river geometry, sediment size patterns, hydraulic habitats, and riverbank erosion patterns. The custom catamaran design we have developed integrates off-the-shelf, lower-cost sensors including high-resolution RTK/PPK GPS, inertial measurement (IMU), side-scan sonar, single-beam sonar, temperature, and a multi-camera array for 3D mapping above and below water. The design is meant to be “garage build friendly”, utilizing a minimum number of common tools and basic construction techniques. The sensor package will be user-friendly enough for non-expert use, allowing the boat to be deployed for citizen-science based data collection by loaning it to groups like watershed councils or volunteer conservation organizations. This will allow data to be collected over larger areas in less time than would be possible by “expert” researchers. The boat designs and software are developed as an open-source project and all hardware and software and will be made public as our testing and validation progress.

How to cite: Dietrich, J., Fonstad, M., and Zettler-Mann, A.: Open-source surface watercraft for Riverscape mapping, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-4291, https://doi.org/10.5194/egusphere-egu2020-4291, 2020.

EGU2020-9114 | Displays | HS1.1.1

Drifting away from reality : A cheap way to get lagrangian measurements

Cristèle Chevalier and Guillaume Koenig

Beauty may sometimes lie in the eyes of the beholder, but in science it always lies in simplicity. We tested a very simple concept to get drifting platforms  that we could track and equip with sensors. We equipped an available floating device with a commercial GPS tracking system.  We tested this in several campaigns ( Italia, New-Caledonia, Tunisia and Guadeloupe) to study surface drifts. Later, we added chemical sensors to collect of lagrangian measurements. Here we present  the general setting of the drifter and the results of the first tests, which proved its efficiency and robustness despite its cheapness and its simplicity to use. We also discuss possibility of adding various kinds of sensors.

How to cite: Chevalier, C. and Koenig, G.: Drifting away from reality : A cheap way to get lagrangian measurements, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-9114, https://doi.org/10.5194/egusphere-egu2020-9114, 2020.

EGU2020-8446 | Displays | HS1.1.1

Low-cost, high accuracy Global Navigation Satellite System positioning for understanding floods

Hessel Winsemius, Andreas Krietemeyer, Kirsten Van Dongen, Ivan Gayton, Frank Annor, Christiaan Tiberius, Marie-Claire Ten Veldhuis, Hubert Samboko, Rolf Hut, and Nick Van de Giesen

Detailed elevation is a prerequisite for many hydrological applications. To name a few, understanding of urban and rural flood hazard and risk; understanding floodplain geometries and conveyance; and monitoring morphological changes. The accuracy of traditional Global Navigation Satellite System (GNSS) chipsets in smart phones is typically in the order of several meters, too low to be useful for such applications. Structure from Motion photogrammetry methods or Light Detection and Ranging (LIDAR), may be used to establish 3D point clouds from drone photos or lidar instrumentation, but even these require very accurate Ground Control Point (GCP) observations for a satisfactory result. These can be acquired through specialised GNSS rover equipment, combined with a multi-frequency GNSS base station or base station network, providing a Real-Time (RTK) or Post-Processing Kinematics (PPK) solution. These techniques are too expensive and too difficult to maintain for use within low resource settings and are usually deployed by experts or specialised firms.

Here we investigate if accurate positioning (horizontal and vertical) can be acquired using a very recently released low-cost multi-constellation dual-frequency receiver (ublox ZED-F9P), connected with a simple antenna and a smart phone. The setup is remarkably small and easy to carry into the field. Using a geodetic (high-grade) GNSS antenna and receiver as base station, initial results over baselines in the order of a few km with the low-cost receiver revealed a positioning performance in the centimeter domain. Currently, we are testing the solution using a smart phone setup as base station within Dar es Salaam, to improve elevation mapping within the community mapping project “Ramani Huria”. We will also test the equipment for use in GCP observations within the ZAMSECUR project in Zambia and TWIGA project in Ghana. This new technology opens doors to affordable and robust observations of positions and elevation in low resource settings.

How to cite: Winsemius, H., Krietemeyer, A., Van Dongen, K., Gayton, I., Annor, F., Tiberius, C., Ten Veldhuis, M.-C., Samboko, H., Hut, R., and Van de Giesen, N.: Low-cost, high accuracy Global Navigation Satellite System positioning for understanding floods, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-8446, https://doi.org/10.5194/egusphere-egu2020-8446, 2020.

For the understanding of the carbon cycle in terrestrial ecosystems as well as of plant stress responses to drought and hypoxia, the study of fine root dynamics plays an important role. However, the number of relevant studies is still limited, which may be due, among other things, to the high costs of commercial minirhizotron systems. Here, we present an affordable (<500 €) and fully automated minirhizotron system, utilizing new developments in low-cost electronics and 3D-printing. The camera system is based on a Raspberry Pi and can be controlled by the user via a Python-based GUI. The open source character of the program also allows it to be adapted to the needs of the user or other requirements. The camera is controlled automatically by a stepper motor, which allows the precise recording of images at defined depths. The highest possible resolution is 3280 x 2464 pixels (8 MP) for an image area of about 2.5 cm x 2.5 cm, thus allowing the imaging of even root hairs and fungal hyphae. The structural components were manufactured using 3D printing. To protect against moisture, the camera and drive system are installed in a waterproof acrylic tube (60 mm diameter), which in turn is inserted into the rhizotron tubes (70 mm diameter) used in the field, making it possible to use the system in humid ecosystems.

How to cite: Thomsen, S. and Jensen, K.: An affordable, fully-automated minirhizotron system for observing fine-root dynamics, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-22448, https://doi.org/10.5194/egusphere-egu2020-22448, 2020.

EGU2020-5584 | Displays | HS1.1.1

Tiny diameter downhole pressure monitoring

Bernd Wiese, Wolfgang Weinzierl, Peter Pilz, Tobias Raab, and Cornelia Schmidt-Hattenberger

Cheap and efficient groundwater pressure monitoring is a standard task in subsurface hydrology. We present application experience from a tube based pressure monitoring system that is applied to the Svelvik field laboratory for CO2  storage, Norway. In total 13 monitoring points were installed in depths between 51 and 89 m below ground level.

The pressure sensor is located above ground. It is temperature compensated to reduce measurement errors due to temperature variations. The pressure sensor is connected to a downhole low diameter tube that has a perforation in the respective measurement depth. The tubes are installed as smart casing installations, i.e. in the borehole annulus. This allows to keep the borehole open during installation of other monitoring devices.

Clean pumping of the well was not possible. Some filters were protected with fleece, while others were just perforated tubes. During installation, all tubes had hydraulic contact to the groundwater. After settling of the mud 3 of 4 fleece protected filters show sufficient communication, while all 9 filters that were just perforated were clogged and not usable for pressure monitoring.

The system has following advantages: (i) the downhole material is robust and cheap, allowing for multiple measurement points; (ii) has a small diameter (6 mm in the present case); (iii) since the static pressure is removed, a smaller sensor range is required; (iv) the sensors are located at the top of the borehole and can be retrieved after the campaign. Further, it can be installed without downhole metal parts.

The system has two disadvantages by design compared to submerged pressure sensors. (i) The absolute pressure can only be approximately determined, limited by the accuracy of the fluid density inside the tube. (ii) Pressure decreases can only be measured up to about 1 bar below piezometric head when the tube is filled with water.

The upper metres, that may be exposed to temperatures below 0 °C are filled with antifreeze. The choice of antifreeze allows for a certain static pressure correction. Minimum weight liquid is pure ethanol with a density of about 0.8 kg, allowing to measure pressure up to 2.8 bars below piezometric head for e.g. the 89 m deep measurement.

Acknowledgements

This work has been produced with support from the SINTEF-coordinated Pre-ACT project (Project No. 271497) funded by RCN (Norway), Gassnova (Norway), BEIS (UK), RVO (Netherlands), and BMWi (Ger-many) and co-funded by the European Commission under the Horizon 2020 programme, ACT Grant Agreement No 691712. We also acknowledge the industry partners for their contributions: Total, Equinor, Shell, TAQA. We thank the SINTEF-owned Svelvik CO2 Field Lab (funded by ECCSEL through RCN, with additional support from Pre-ACT and SINTEF) for assistance during installation and for financial support.

How to cite: Wiese, B., Weinzierl, W., Pilz, P., Raab, T., and Schmidt-Hattenberger, C.: Tiny diameter downhole pressure monitoring , EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-5584, https://doi.org/10.5194/egusphere-egu2020-5584, 2020.

EGU2020-5819 | Displays | HS1.1.1

Application of a low-cost NDIR sensor module for measurements of in situ soil CO2 concentration

Adrian Heger, Volker Kleinschmidt, Alexander Gröngröft, Lars Kutzbach, and Annette Eschenbach

We applied the low-cost non-dispersive infrared sensor module K33 (ICB, Senseair, Sweden) for measurements of soil CO2 concentration. We integrated the sensor module in a new soil probe suitable for in situ measurements of soil gas CO2 concentration. Therefore, we covered the sensor module with epoxy resin. For continuous measurements, we connected our soil CO2 probe to a microcontroller (MEGA 2560 Rev3, Arduino.cc, Italy) equipped with a data logging shield (Adalogger FeatherWing, Adafruit, USA). In a laboratory experiment, we evaluated the accuracy and precision of our soil CO2 probe at changing temperature and humidity by comparison with the often used CO2 probe GMP343 (Vaisala, Finland) as a reference. In a field experiment, we buried our soil CO2 probe to test its performance under natural environmental conditions.

The result of the laboratory experiment is that our soil CO2 probe compares well with the GMP343, even at maximum relative humidity. The accuracy (<0.1 % CO2) was below the accuracy given by the manufacturer. The field experiment demonstrated that our soil CO2 probe provides high-quality measurements of soil CO2 concentrations under in situ soil conditions. After retrieving it, it still measured with the same accuracy and precision as before.

In summary, we used the sensor module K33 for the first time to measure in situ soil CO2 concentrations by integrating it into a newly developed probe. The cost-efficient availability of our CO2 probe opens up the opportunity to carry out continuous soil CO2 measurements over long time periods with simultaneously high spatial resolution.

How to cite: Heger, A., Kleinschmidt, V., Gröngröft, A., Kutzbach, L., and Eschenbach, A.: Application of a low-cost NDIR sensor module for measurements of in situ soil CO2 concentration, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-5819, https://doi.org/10.5194/egusphere-egu2020-5819, 2020.

EGU2020-10966 | Displays | HS1.1.1 | Highlight

MEMS Accelerometers Mini-Array (MAMA) - initial results and lessons learned

Ran N. Nof, Angela I. Chung, Horst Rademacher, and Richard M. Allen

Most operational earthquake early warning systems (EEWS) consider earthquakes to be point-sources and have difficulty providing imminent and robust source locations and magnitudes, especially at the edge of the seismic network or where seismic stations are sparse. Mini-arrays have the potential to estimate reliable hypocentral locations by beam forming (FK-analysis) techniques. They can also characterize the rupture dimensions and account for finite-source effects, leading to more reliable estimates of ground motions for large magnitude earthquakes. In the past, the high price of multiple seismometers has made creating arrays cost- prohibitive. Here, we present a setup of two mini-arrays of a new low-cost (<$150) seismic acquisition unit based on a high-performance MEMS accelerometer around conventional seismic stations. The expected benefits of such an approach include decreasing alert-times, improving real-time shaking predictions and mitigating false alarms.

We will present our new 24-bit device details, benchmarks, and results from two MAMAs deployed at the UC Berkeley and Humboldt State University campuses. The new device shows lower noise levels than the currently available off-the-shelf 16-bit sensors, commonly used by several citizen-science projects (e.g. QCN, CSN, MyShake, etc.). This lower noise level enables us to record and process lower magnitude events. We show examples of back-azimuth calculations of M>=2.5 events at a range of <100km from the MAMA center and discuss some of the limitations and considerations of the MAMA deployments.

How to cite: Nof, R. N., Chung, A. I., Rademacher, H., and Allen, R. M.: MEMS Accelerometers Mini-Array (MAMA) - initial results and lessons learned, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-10966, https://doi.org/10.5194/egusphere-egu2020-10966, 2020.

The work sets out a method and evaluates the accuracy of a 3D printed turbine flow meter for open channel and pipe flow; that can be optimised for different situations.  The motivation for this project was to create flow meters that are low cost and available to community groups and interested individuals, this work was conducted as part of the CAMELLIA project (Community Water Management for a Liveable London).  The flowmeters have been trialled in a number of locations by users with different skill sets and technical know-how.  Hall effect sensors have been coupled with consumer grade electronics to develop the most opensource system possible.  This work has taken advantage of recent advances in DLP printing, allowing for greater resolution at a lower cost than previous generations of 3D printers.  This is combined with work developed by the Open Prop software team, has enabled user customisable sensors to be built.  

The presented work aims to create an opensource, low cost and easy to use solution to some flow monitoring problems.  This paper details the lessons learnt and successes of this approach; it aims to create a basis for which further development and deployment of these sensors can be achieved.  

How to cite: Butler, A., Rowan, T., and Colyer, A.: On the development of low cost, optimizable, 3D printed turbine flow meters for pipe and open channel applications, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-21929, https://doi.org/10.5194/egusphere-egu2020-21929, 2020.

EGU2020-2953 | Displays | HS1.1.1

Night-Time Cooling of Surface Water: Laboratory experiment and numerical simulation

Nick van de Giesen, John Selker, Koen Hilgersom, and Anna Solcerova

In the framework of the Small Reservoirs Project (www.smallreservoirs.org), evaporation in semi-arid areas from open water has been measured through water balances, floating evaporation pans, and eddy covariance measurements. Each method showed that the actual evaporation was 30%-50% less than the evaporation from open water as predicted by Penman. During daytime, this reduced evaporation may be due to the formation of a stable internal boundary layer over the reservoirs. One would expect that this evaporation reducing effect would at least partially be offset during the night when the warm water would induce strong turbulent transport through an unstable local boundary layer. Through detailed Distributed Temperature Sensing observation in ponds, lakes, and reservoirs in different parts of the world, it was observed that during cloudless nights with low wind speeds or no wind, the top layer (1cm-2cm) of the water was one to two degrees colder than the air immediately above it. Such a temperature difference would again set up a stable layer, hindering turbulent transport of heat and water vapor into the atmosphere. 

 

It was hypothesized that outward longwave radiation, which during cloudless nights can quickly reach 200 W/m2, would cause a thin layer of cold water on top of the warmer water body. Through conduction, this cold layer would grow until it would become unstable, at which point the surface would be (partially) refreshed through downward finger flow. Detailed numerical simulations of the heat transport in the water body were undertaken to test this hypothesis. The numerical results indeed showed the cooling of the top layer and formation of instabilities with characteristic length and time scales. To test these results and the general concept, a MacGyver-worthy laboratory set-up was built consisting of an insulated 20 liter bucket, covered by a double hemispheric dome of perspex. On the inside of the dome, a thermal camera was attached at the apex. The space between the inner and outer dome was filled with dry ice to create an inside surface temperature of about 230K. After the dry ice was added, surface cooling was observed, followed by the formation of zones with upwelling warm water and downwelling cold water. These circulation cells were comparable in size to the simulated ones. A detailed analysis of spatial and temporal scales of the laboratory and simulation results will be presented.

How to cite: van de Giesen, N., Selker, J., Hilgersom, K., and Solcerova, A.: Night-Time Cooling of Surface Water: Laboratory experiment and numerical simulation, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-2953, https://doi.org/10.5194/egusphere-egu2020-2953, 2020.

EGU2020-22195 | Displays | HS1.1.1

Novel methods for identifying and quantifying hyporheic exchange fluxes using Fibre Bragg Grating sensor arrays

John Arkwright, Eddie W Banks, Margaret Shanafield, and Anthony Papageorgiou

Most streambed heat tracer studies use vertical, ambient temperature profiles and a 1D analytical solution of the heat diffusion–advection equation to estimate hyporheic exchange fluxes (HEF). This approach has limited capacity in complex flow settings, which has led to the successful development of active heat pulse sensing to investigate the dynamic 3D flow fields in the near subsurface and to quantify HEF. At the scale of the hyporheic zone very small water level fluctuations drive changes in the hydraulic gradients across streambed bedform structures. Generally, hydraulic head gradients are measured with pressure sensors deployed in shallow monitoring wells, but such devices do not have the required vertical spatial resolution and precision to accurately evaluate these processes. New and novel research developed by the biomedical community for in-vivo medical devices can now be used in the geosciences field to measure temperature and pressure at a much higher spatial and temporal resolution to overcome these challenges. As part of this research we have developed a fibre optic, active heat pulse and pressure sensing instrument (formed from Fibre Bragg Grating sensor arrays) to determine small hydraulic gradients in the subsurface and to quantify the exchange fluxes. The instrument was tested in a controlled laboratory environment and in the field. Combining point-scale measurements from this novel instrument with near surface geophysical data and other hydrological observations (i.e. measurements with fibre optic distributed temperature sensing) can be used to upscale some of the key physical exchange processes to the stream reach and river scale.

How to cite: Arkwright, J., Banks, E. W., Shanafield, M., and Papageorgiou, A.: Novel methods for identifying and quantifying hyporheic exchange fluxes using Fibre Bragg Grating sensor arrays, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-22195, https://doi.org/10.5194/egusphere-egu2020-22195, 2020.

Satellite data for West Africa still struggle with local climate and farming practices. Despite the increasing data frequency, the rainy season in West Africa features such a dense cloud cover that many satellites cannot provide cloud free images. In addition, many farmers practice intercropping, where a single plot can be used to grow different crops such as maize and beans or even feature trees. Although the spatial resolution of satellites is ever increasing, this very small-scale intercropping still poses challenges for satellite data analysis. Yet, spatial data on vegetation status and distribution is required for running crop models.

Within the EU project TWIGA we therefore developed a smartphone app that allows farmers to collect vegetation data where it matters – on their plot!

Based on field trial that started in August 2019 we present vegetation metrics derived from smartphone photos as well as auxiliary data collected by test users in Ghana. The vegetation metrics are further combined with Sentinel 2A NDVI timeseries and fill a cloud cover caused data gap during the peak growing season.

How to cite: Ahmed, S. and Friesen, J.: Farmers see where the satellite is blind – using citizen science to fill satellite-derived vegetation data gaps, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-13145, https://doi.org/10.5194/egusphere-egu2020-13145, 2020.

HS1.1.3 – Innovative methods for non-invasive monitoring of hydrological processes from field to catchment scale

EGU2020-10728 | Displays | HS1.1.3

Scene Setting for the ESA HydroGNSS GNSS-Reflectometry Scout Mission

Martin Unwin, Nazzareno Pierdicca, Kimmo Rautiainen, Estel Cardellach, Giuseppe Foti, Paul Blunt, Michel Tossaint, and Elliott Worsley

HydroGNSS is a mission concept selected by ESA as a Scout candidate, and consists of a 40 kg satellite that addresses land hydrological parameters using the technique of GNSS Reflectometry, a form of bistatic L-Band radar using satnav signals as the radar source. The four targeted essential climate variables (ECVs) are of established importance to our understanding of the climate evolution and human interaction, and comprise of soil moisture, inundation / wetlands, freeze /thaw (notably over permafrost) and above ground biomass.

The technique of GNSS Reflectometry shows potential over all geophysical surfaces for low cost measurement of ocean winds, ocean roughness, soil moisture, flood & ice mapping, and other climate and operational parameters. SSTL developed and flew the SGR-ReSI GNSS remote sensing instrument on the 160 kg UK TechDemoSat-1 (TDS-1) in July 2014 and, with sponsorship from ESA, collected data until TDS-1’s drag-sail was deployed in May 2019. TDS-1 was a precursor for NASA’s CYGNSS mission which uses the SGR-ReSI on its 8-microsatellite constellation for sensing hurricanes. The datasets from TDS-1 have been released via the MERRByS website, and include ocean wind speed measurements and ice extent maps from National Oceanography Centre’s C-BRE inversion. At the same time, researchers recognised the benefits of GNSS reflectometry over land, including the unique capability to sense rivers under forest canopies to a high resolution.

HydroGNSS has been proposed for the ESA Scout mission opportunity by a SSTL and a team of partners with a broad range of experience in GNSS technology, GNSS-Reflectometry modelling and applications, and Earth Observation from GNSS-R measurements. The instrument takes significant steps forward from previous GNSS-R experiments by including capability in dual polarisation, dual frequency and coherent reflected signal reception, that are expected to help separate out ECVs and improve measurement resolution. The satellite platform is the 40 kg SSTL-Micro, which has improved attitude determination and a high data link to support the collection of copious quantities scientific data with a short time delay. HydroGNSS builds upon the growing GNSS-R knowledge gained from UK-DMC, TDS-1, and ORORO / DoT-1, and is anticipated to generate a new research data set in GNSS Earth Observation, specifically targeting land and hydrological applications.

State of the art satellites that target soil moisture such as ESA SMOS and NASA SMAP are highly valued by scientists and operational weather forecasters, but will be expensive to replace. As evidenced by TDS-1 and CYGNSS, HydroGNSS will be able to take GNSS-R measurements using GNSS signals as a radar source, reducing the size of the satellite platform required. The forward scatter L-band nature of the measurement means that they are complementary to other techniques, and HydroGNSS brings further new measurement types compared to TDS-1 and CYGNSS. The small size and low recurring cost of the HydroGNSS satellite design opens the door to a larger constellation that can further improve spatial and temporal global hydrological measurements to an unprecedented resolution, invaluable to the better understanding of our climate.

How to cite: Unwin, M., Pierdicca, N., Rautiainen, K., Cardellach, E., Foti, G., Blunt, P., Tossaint, M., and Worsley, E.: Scene Setting for the ESA HydroGNSS GNSS-Reflectometry Scout Mission, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-10728, https://doi.org/10.5194/egusphere-egu2020-10728, 2020.

EGU2020-8285 | Displays | HS1.1.3

Monitoring intermittent streams with low-cost water-presence sensors

Francesca Zanetti, Nicola Durighetto, Filippo Vingiani, and Gianluca Botter

The study of intermittent and ephemeral streams is gaining more and more popularity, as the scientific community has acknowledged the fundamental impact of these streams on basic hydrological processes and important ecosystem services. Nevertheless, the understanding of the physical processes that drive this intermittency has been long hampered by the limited availability of empirical data. In fact, monitoring the event-based expansion and contraction of temporary streams through visual inspection is very demanding and time-consuming. To circumvent this limitation, several low-cost sensor designs for monitoring flow presence have been suggested in recent years. These sensor exploit either water temperature or electrical conductivity. However, these sensors are typically characterized by pointwise probes that water flows can easily dodge, particularly in streams with complex and unstable morphologies. Moreover, very few studies have been conducted that use networks of probes to monitor stream intermittency at the catchment-scale.

Here we present a field-application of an advanced version of the low-cost water presence sensor developed by Chapin et al., 2016. In particular, we tested a new probe design to continuously measure the electrical conductivity across a channel cross-section and, thus, infer the presence of water therein. More than 50 probes were installed to monitor the dynamics of several intermittent tributaries of a small headwater catchment in northern Italy during the summer and fall of 2019. This catchment encompasses a wide variety of stream types: mild and steep slopes, incised and flat geometries, rocky and vegetated riverbeds. The field application shows that the proposed probes are able to provide useful information about the temporary activation of ephemeral streams under a variety of environments and conditions. The reconstructed temporal dynamics of the stream network comply with the persistency maps previously derived based on visual inspection. This new sensor design enables the continuous-time monitoring of the activity of intermittent streams, providing easily interpretable data under diverse conditions. We conclude that low-cost water presence sensors provide a unique opportunity to expand the coverage of the available datasets about the dynamics of intermittent streams.

How to cite: Zanetti, F., Durighetto, N., Vingiani, F., and Botter, G.: Monitoring intermittent streams with low-cost water-presence sensors, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-8285, https://doi.org/10.5194/egusphere-egu2020-8285, 2020.

EGU2020-11751 | Displays | HS1.1.3

Proximal remote sensing to quantify plot-scale overland flow connectivity

Chandra Prasad Ghimire, Val Snow, Stuart Bradley, and Laura Grundy

Irrigation of crops and grazed pastures can lead to harmful losses of nutrients via overland flow across the edge of the field. While good irrigation design can assist with avoiding overland flow, soil surface conditions can change rapidly and lead to surface flow even under well-designed irrigation systems. Therefore, real-time methods to detect emerging flow conditions, early enough to prevent substantial flow from the field during irrigation, is a potential mitigation option. But these methods require a prediction of the initiation of overland flow conditions in order to make the connection with real-time observations.

On a naturally-rough agricultural soil, triggering of overland flow is primarily related to the process of gradual filling of small (~50 mm across) depressions. As depressions fill, hydraulic connections are established with their neighbours and this eventually leads to sufficient connectivity that overland flow is initiated. The initiation of overland flow generally occurs at a critical value of connectivity (COF); the proportion of the soil surface that is connected via a water-filled pathway to an exit point of the field. As water ponding in, and flowing through, local depressions increases, the COF of the field increases and this leads to flow across the field boundaries. Quantifying the development of COF during an irrigation event, therefore, is key to predicting the initiation of overland flow.

We propose a method to continuously monitor the development of COF during an irrigation event that requires two elements. The first is a new proximal sensing technique, which exploits acoustic technology to continuously monitor Asw, the proportion of the soil surface covered in water. The acoustic method comprises directional acoustic transmitter and receiver arrays. The directionality of the arrays provides a well-defined footprint area on the ground beneath the instrument. The Asw can be reliably estimated from changes in the amplitude of reflected sound waves. The second element is a ponding and redistribution model which simulates the flow of water over a rough soil surface and assists by converting Asw into COF.

Our preliminary results show that this real-time method of monitoring COF has a considerable scope in a variety of environments where prediction of overland flow initiation is desirable.

How to cite: Ghimire, C. P., Snow, V., Bradley, S., and Grundy, L.: Proximal remote sensing to quantify plot-scale overland flow connectivity, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-11751, https://doi.org/10.5194/egusphere-egu2020-11751, 2020.

EGU2020-16516 | Displays | HS1.1.3

Large-scale alternative detection systems for CRNS

Markus Köhli, Jannis Weimar, and Ulrich Schmidt

Cosmic-Ray neutron (CRN) sensors are widely used to determine soil moisture on the hectar scale. Precise measurements, especially in the case of mobile application, demand for neutron detectors with high counting rates and high signal-to-noise ratios. For a long time CRNS instruments have relied on helium-3 as an efficient neutron converter. Its ongoing scarcity demands for technological solutions using alternative converters, which are lithium-6 and boron-10. In order to scale up the method and to reduce costs we recently have developed large-scale neutron detectors including readout electronics and data acquisition systems based on Arduino microcontrollers. These boron-lined detectors shall offer an alternative platform to current Helium-3 based systems and allow for modular instrument designs. Individual shieldings of different segments within the detector introduces the capability of gaining spectral information. This opens the possibility for active signal correction during mobile measurements, where the influence of the constantly changing near-field to the overall signal should be corrected. Furthermore, the signal-to-noise ratio could be increased by combining pulse-height and pulse-length spectra to discriminate between neutrons and other environmental radiation. This novel detector therefore combines high-selective counting electronics with large-scale instrumentation technology. The successful implementation of our design allowed also to build the largest up to now existing CRNS detector. 

How to cite: Köhli, M., Weimar, J., and Schmidt, U.: Large-scale alternative detection systems for CRNS, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-16516, https://doi.org/10.5194/egusphere-egu2020-16516, 2020.

EGU2020-11180 | Displays | HS1.1.3

Local high-energy particles measurements for detecting primary cosmic-ray variations: application for soil moisture estimation

Luca Stevanato, Gabriele Baroni, Cristiano Fontana, Marcello Lunardon, Sandra Moretto, and Paul Schattan

In the last decade the measurement of secondary cosmic ray neutrons has been established as a unique approach for intermediate scale observation of land surface hydrogen pools. Originally developed for soil moisture measurements, it has shown also promising applications for snow, biomass and canopy interception. The approach relies on the correlation between natural neutron background as created by cosmic-ray fluxes and local hydrogen pools. Due to the specific capabilities of the neutrons to move in air, the signal detected by the sensor installed above-ground is sensitive to an area of hundreds of meters providing a new perspective for proximal land-surface observations. The measurements are generally performed based on moderated proportional counters filled with Helium-3 or Boron and the moderation is created by adding shielding material (mostly polyethylene) around the counter.

The signal is affected by the temporal variability of the incoming neutron fluxes. At first, the variability of neutron fluxes is due to solar activities. The neutrons are further attenuated by the mass of the air and air humidity.

Specific corrections have been proposed to account for these effects. Air pressure and humidity corrections rely on local measurements that could be easily collected. Incoming correction due to solar cosmic-ray fluctuation is based on a worldwide network monitoring station (NMDB). This network provides online access to their data in real-time. However, this approach showed some limitations in region where incoming fluxes could be not representative of local conditions introducing errors that could be relevant for the estimation of the targeted variable. In addition, it requires the need of post-processing of the data resulting in some difficulties to provide, e.g., soil moisture observations in real-time.

In the present contribution, we show the results of tests conducted on an alternative commercial sensor based on scintillators. The new probe has the capability to identify different neutron energies ranges and gamma-rays providing new opportunities for hydrological observations at different spatial scales. In addition, the probe is sensitive to high energy particles that can be used for correcting the neutron signal by the variations of primary cosmic-ray flux. We present results from the comparison of the new probe with standard proportional counters and neutron monitor database in a long-term outdoor case study. We show how the use of local high energy particles is a practical alternative to account atmospheric corrections and overcome the limitation of using data from NMDB.

How to cite: Stevanato, L., Baroni, G., Fontana, C., Lunardon, M., Moretto, S., and Schattan, P.: Local high-energy particles measurements for detecting primary cosmic-ray variations: application for soil moisture estimation, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-11180, https://doi.org/10.5194/egusphere-egu2020-11180, 2020.

EGU2020-17856 | Displays | HS1.1.3

Moisture and humidity dependence of the above-ground cosmic-ray neutron intensity

Jannis Weimar, Markus Köhli, Martin Schrön, and Ulrich Schmidt

The novel method of Cosmic-ray neutron sensing (CRNS) allows non-invasive soil moisture measurements at a hectometer scaled footprint. Using this technique one can relate the flux density of albedo neutrons, generated in cosmic-ray induced air showers, to the amount of water within a radius of several hundred meters. In the recent years the understanding of neutron transport by Monte Carlo simulations led to major advancements in precision, which have successfully targeted a manifold of use cases. For example the improvements in the signal interpretation have meanwhile also been applied to the determination of snow water in Alpine regions. Up to now, the conversion of soil moisture to a detectable neutron count rate relies mainly on the equation presented by Desilets and Zreda. While in general a hyperbolic expression can be derived from theoretical considerations, their empiric parameterisation needs to be revised as many groups have found site-specific calibrations, which are simply based on different empirical data sets.

Investigating the above-ground neutron intensity by a broadly based Monte Carlo simulation campaign revealed a more detailed understanding of different contributions to this signal, especially targeting air humidity corrections. The packages MCNP and URANOS were used to derive a function able to describe the respective dependencies including the effect of different hydrogen pools and the sensor response function. The resulting formula significantly improves the soil-moisture-to-intensity conversion and allows for a more comprehensive instrument data quality, which especially closes the gap between observations of very dry and wet conditions.

How to cite: Weimar, J., Köhli, M., Schrön, M., and Schmidt, U.: Moisture and humidity dependence of the above-ground cosmic-ray neutron intensity, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-17856, https://doi.org/10.5194/egusphere-egu2020-17856, 2020.

A Critical Zone Observatory (CZO) was recently established in the Alento River Catchment (ARC; southern Italy) within the TERENO (TERrestrial ENvironmental Observatories) long-term ecosystem infrastructure network. In 2016 SoilNet wireless sensor networks and cosmic ray neutron probes (CRNP) were installed in the upper part of this catchment and specifically in two experimental sub-catchments (MFC2 and GOR1) characterized by different topographic, pedological, land-use, and weather conditions. The Soilnet end-devices are monitoring soil moisture and matric potential at two different soil depths (15 cm and 30 cm) in 20 locations around the cosmic ray neutron probe. We evaluated the the relationship between Soil Moisture Index (SMI) and rainfall deficits (considered as rainfall minus potential evapotranspiration) at monthly time scale. The cropland site on the south-facing hillslope of ARC is characterized by more extreme dry and wet conditions. Another goal is to identify the dominant controls that most govern the spatial soil moisture patterns in these two different sites. The relationship between the CRNP-based soil moisture and spatial variability of SoilNet-based soil moisture is nearly linear in the case of the cropland site (MFC2) but follows a fairly concave curve in the case of the forestland site (GOR1). The majority of the spatial variance in MFC2 is explained by terrain attributes, i.e. slope-induced during wet conditions and aspect-induced during dry conditions. In GOR1 the spatial variance of soil moisture data is mostly explained by topographic factors under wet conditions during the rainy season. In both sites the soil texture is able to explain only less than 10% of spatial variability of soil moisture data.

How to cite: Nasta, P., Bogena, H., Sica, B., Vereecken, H., and Romano, N.: Understanding the spatio-temporal variability of soil moisture by integrating cosmic-ray neutron probes with SoilNet wireless sensor netwoks under a seasonal Mediterranean-climate regime, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-5295, https://doi.org/10.5194/egusphere-egu2020-5295, 2020.

EGU2020-4093 | Displays | HS1.1.3

Development of irrigation management services based on integration of innovative soil moisture monitoring and hydrological modelling

Vassilios Pisinaras, Cosimo Brogi, Heye Bogena, Harrie-Jan Hendricks-Franssen, Olga Dombrowski, and Andreas Panagopoulos

The H2020 ATLAS project (www.atlas-h2020.eu/) aims to develop an open, flexible and distributed platform that will provide services for the agricultural sector based on the seamless interconnection of sensors and machines. Two interconnected services that will be included in the platform are the soil moisture monitoring and the irrigation management services. The soil moisture monitoring service will integrate both invasive (wireless sensor network (SoilNet)) and non-invasive soil moisture monitoring methods (cosmic-ray neutron sensors (CRNS)). Ultimately, a model will be developed that combines SoilNet and CRNS measurements to predict soil moisture time series. Soil water potential sensors will be incorporated as well.

Data provided by the above described service will be incorporated in an irrigation management service which will be based on hydrological modelling. The fully distributed, deterministic Community Land Model (CLM, version 5) will be applied which incorporates physically-based simulation of soil water balance and crop growth. Two different levels of application will be considered, namely the farm and watershed scale, which will be combined to weather forecast in order to provide irrigation scheduling advice. The farm scale application will take advantage of soil moisture monitoring data and provide farm specific irrigation scheduling, while the watershed scale application will provide a more generic irrigation advice based on the average cultivation practices. Furthermore, the CLM model will be coupled to a groundwater flow model in order to connect irrigation to groundwater availability. By doing so, it will be possible to support the efficient and sustainable groundwater management as well as competent water uses in an area that suffers from water scarcity.

These services will be implemented in the area of Pinios Hydrologic Observatory, located in central Greece. Three pilot orchards will be established introducing different soil moisture monitoring setups, while the boundaries of the Observatory will be used for the pilot implementation of irrigation management service on the watershed scale. Furthermore, two pilot vineyards located in northern Greece will be established in order to further test the services functionality on the farm scale.

How to cite: Pisinaras, V., Brogi, C., Bogena, H., Hendricks-Franssen, H.-J., Dombrowski, O., and Panagopoulos, A.: Development of irrigation management services based on integration of innovative soil moisture monitoring and hydrological modelling, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-4093, https://doi.org/10.5194/egusphere-egu2020-4093, 2020.

EGU2020-4618 | Displays | HS1.1.3

Field scale root zone soil moisture estimation by coupling cosmic-ray neutron sensor with soil moisture sensors

Hami Said, Georg Weltin, Lee Kheng Heng, Trenton Franz, Emil Fulajtar, and Gerd Dercon

Since it has become clear that climate change is having a major impact on water availability for agriculture and crop productivity, an accurate estimation of field-scale root-zone soil moisture (RZSM) is essential for improved agricultural water management. The Cosmic Ray Neutron Sensor (CRNS) has recently been used for field-scale soil moisture (SM) monitoring in large areas and is a credible and robust technique. Like other remote or proximal sensing techniques, the CRNS provides only SM data in the near surface. One of the challenges and needs is to extend the vertical footprint of the CRNS to the root zone of major crops. This can be achieved by coupling the CRNS measurements with conventional methods for soil moisture measurements, which provide information on soil moisture for whole rooting depth.

The objective of this poster presentation is to estimate field-scale RZSM by correlating the CRNS information with that from soil moisture sensors that provide soil moisture data for the whole root depth. In this study, the Drill and Drop probes which provide continuous profile soil moisture were selected. The RZSM estimate was calculated using an exponential filter approach.

Winter Wheat cropped fields in Rutzendorf, Marchfeld region (Austria) were instrumented with a CRNS and Drill & Drop probes. An exponential filter approach was applied on the CRNS and Drill and drop sensor data to characterize the RZSM. The preliminary results indicate the ability of the merging framework procedure to improve field-scale RZSM in real-time. This study demonstrated how to combine the advantages of CRNS nuclear technique (especially the large footprint and good representativeness of obtained data) with the advantages of conventional methods (providing data for whole soil profile) and overcome the shortcoming of both methods (the lack of information in the deeper part of soil profile being the major disadvantage of CRNS and the spatial limitation and low representativeness of point data being the major disadvantage of conventional capacitance sensors). This approach can be very helpful for improving agricultural water management.

How to cite: Said, H., Weltin, G., Heng, L. K., Franz, T., Fulajtar, E., and Dercon, G.: Field scale root zone soil moisture estimation by coupling cosmic-ray neutron sensor with soil moisture sensors, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-4618, https://doi.org/10.5194/egusphere-egu2020-4618, 2020.

EGU2020-7668 | Displays | HS1.1.3

Long-term soil moisture observations using cosmic-ray neutron sensing in Austria

Emil Fulajtar, Hami Said Ahmed, Ammar Wahbi, Gabriele Baroni, Rafael Rosolem, Daniel Power, Trenton Franz, and Lee Kheng Heng

This study presents the results of soil moisture investigation carried by the Joint FAO/IAEA Division using Cosmic-Ray Neutron Sensor (CRNS). The measurements have been collected at several studied sites in Austria. The Petzenkirchen study which is within the Austrian Institute for Land and Water Management Research employing stationary CRNS has been established in Dec. 2013 and it provides major dataset for this study. It represents small watershed in hilly area of northern footslopes of Alps. Apart of that the short-term measurement campaigns were carried out using back-pack CRNS in alluvial plain east of Neusiedler See and in mountainous areas of Rauris Municipality in central part of Austrian Alps.

This study describes the results and interpretation of about 7 years of soil moisture data set (2013-2020). The analysis focused on improving the calibration approaches, CRNS footprint, heterogeneity soil moisture mapping, impacts of biomass and altitude on neutron counts. Further, the use of CRNS data for calibrating soil moisture calculated by soil water balance model was tested. The overall application is aimed at supporting agricultural water management and in developing methodology for soil moisture monitoring for water management in agriculture (under rainfed agriculture as well as for irrigation scheduling). This unique data-set can also provide additional information for hydrological modelling and remote sensing applications (at regional and global scales), as well as for extreme weather events (drought and flood) management and forecasting.

How to cite: Fulajtar, E., Said Ahmed, H., Wahbi, A., Baroni, G., Rosolem, R., Power, D., Franz, T., and Kheng Heng, L.: Long-term soil moisture observations using cosmic-ray neutron sensing in Austria, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-7668, https://doi.org/10.5194/egusphere-egu2020-7668, 2020.

EGU2020-8488 | Displays | HS1.1.3

Error estimation for soil moisture measurements with cosmic-ray neutron sensing and implications for rover surveys

Jannis Jakobi, Johan Alexander Huisman, Martin Schrön, Justus Fiedler, Cosimo Brogi, Harry Vereecken, and Heye Bogena

The cosmic ray neutron (CRN) probe is a non-invasive device to measure soil moisture at the field scale. This instrument relies on the inverse correlation between aboveground epithermal neutron intensity (1eV – 100 keV) and environmental water content. The measurement uncertainty of the neutron detector follows Poisson statistics and thus decreases with decreasing neutron intensity, which corresponds to increasing soil moisture. In order to reduce measurement uncertainty (e.g. < 0.03 m3/m3), the neutron count rate is often aggregated over large time windows (e.g. 12h or 24h). To enable shorter aggregation intervals, the measurement uncertainty can be reduced either by using more efficient detectors or by using arrays of detectors, as in the case of CRN rover applications. Depending on soil moisture and driving speed, aggregation of neutron counts may also be necessary to obtain sufficiently accurate soil moisture estimates in rover applications. To date, signal aggregation has not been investigated sufficiently with respect to the optimisation of temporal (stationary probes) and spatial (roving applications) resolution. In this work, we present an easy-to-use method for uncertainty quantification of soil moisture observations from CRN sensors based on Gaussian error propagation theory. We have estimated the uncertainty using a third order Taylor expansion and compared the result with a more computationally intensive Monte Carlo approach and found excellent agreement. Furthermore, we used our method to quantify the dependence of soil moisture uncertainty on CRN rover survey design and on selected aggregation time. We anticipate that the new approach helps to quantify cosmic ray neutron measurement uncertainty. In particular, it is anticipated that the strategic planning and evaluation of CRN rover surveys based on uncertainty requirements can be improved considerably.

How to cite: Jakobi, J., Huisman, J. A., Schrön, M., Fiedler, J., Brogi, C., Vereecken, H., and Bogena, H.: Error estimation for soil moisture measurements with cosmic-ray neutron sensing and implications for rover surveys, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-8488, https://doi.org/10.5194/egusphere-egu2020-8488, 2020.

EGU2020-8827 | Displays | HS1.1.3

Cosmic-ray neutron sensing based monitoring of snowpack dynamics: A comparison of four conversion methods

Heye Reemt Bogena, Frank Herrmann, Jannis Jakobi, Vassilios Pisinaras, Cosimo Brogi, Johan Alexander Huisman, and Andreas Panagopoulos

Snow monitoring instruments like snow pillows are influenced by disturbances such as energy transport into the snowpack, influences from wind fields or varying snow properties within the snowpack (e.g. ice layers). The intensity of epithermal neutrons that are produced in the soil by cosmic radiation and measured above the ground surface is sensitive to soil moisture in the upper decimetres of the ground within a radius of hectometres. Recently, it has been shown that aboveground cosmic ray neutron sensors (CRNS) are also a promising technique to monitor snow pack development thanks to the larger support that they provide and to the lower need for maintenance compared to conventional sensor systems. The basic principle is that snow water moderates neutron intensity in the footprint of the CRNS probe. The epithermal neutrons originating from the soil become increasingly attenuated with increasing depth of the snow cover, so that the neutron intensity measured by the CRN probe above the snow cover is directly related to the snow water equivalent.

In this paper, we use long-term CRNS measurements in the Pinios Hydrologic Observatory, Greece, to test different methods for the conversion from neutron count rates to snow pack characteristics, namely: i) linear regression, ii) the standard N0-calibration function, iii) a physically-based calibration approach and iv) the thermal to epithermal neutron ratio. The latter was also tested for its reliability in determining the start and end of snowpack development, respectively. The CRNS-derived snow pack dynamics are compared with snow depth measurements by a sonic sensor located near the CRNS probe. In the presentation, we will discuss the accuracy of the four conversion methods and provide recommendations for the application of CRNS-based snow pack measurements.

How to cite: Bogena, H. R., Herrmann, F., Jakobi, J., Pisinaras, V., Brogi, C., Huisman, J. A., and Panagopoulos, A.: Cosmic-ray neutron sensing based monitoring of snowpack dynamics: A comparison of four conversion methods, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-8827, https://doi.org/10.5194/egusphere-egu2020-8827, 2020.

EGU2020-22317 | Displays | HS1.1.3

Monitoring and Mapping of Soil and Snow Water Across Scales with Cosmic-Ray Neutron Sensor Networks and Mobile Platforms

Martin Schrön, Sascha E Oswald, Steffen Zacharias, Peter Dietrich, and Sabine Attinger

Cosmic-ray neutron albedo sensing (CRNS) is a modern technology that can be used to non-invasively measure the average water content in the environment (i.e., in soil, snow, or vegetation). The sensor footprint encompasses an area of 10-15 hectares and extends tens of decimeters deep into the soil. This method might have the potential to bridge the scale gap between conventional in-situ sensors and remote-sensing data in both, the horizontal and the vertical domain.

Currently, more than 200 sensors are operated in the growing networks of national and continental observatories. While single CRNS stations are continuously monitoring the local water dynamics at fixed field sites, mobile CRNS platforms are used for on-demand soil moisture mapping at the regional scale. The sensors are rapidly operational on any ground- or airborne vehicle. The data is particularly useful to study hydrological extreme events, heatwaves, and snow melt/accumulation, and it is being applied in hydrological models and agricultural irrigation management.

In the presentation we will explore the potential of the CRNS method to support and complement in-situ and remote-sensing data for hydrological event monitoring. We will discuss ongoing research activities that are aimed at improving the operationality, frequency, and spatial extend of CRNS measurements. New measurement strategies that are currently explored are, for example: dense clusters of 20 CRNS stations fully covering a 100 hectare catchment; heat wave monitoring with mobile car-based CRNS; regular soil/snow water mapping using mobile CRNS on cars and trains; and airborne surveys using CRNS on gyrocopters.

Future CRNS observations could provide a valuable contribution to the multi-sensor approach, e.g. to help tracking and characterizing surface water movement, to map regional-scale soil moisture patterns, or to calibrate and evaluate satellite data.

How to cite: Schrön, M., Oswald, S. E., Zacharias, S., Dietrich, P., and Attinger, S.: Monitoring and Mapping of Soil and Snow Water Across Scales with Cosmic-Ray Neutron Sensor Networks and Mobile Platforms, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-22317, https://doi.org/10.5194/egusphere-egu2020-22317, 2020.

EGU2020-18563 | Displays | HS1.1.3

Dynamic groundwater recharge rates at field scale: how to successfully use soil moisture from cosmic-ray neutron sensing

Lena M. Scheiffele, Matthias Munz, Gabriele Baroni, Sonja Bauer, and Sascha E. Oswald

Cosmic-ray neutron sensing (CRNS) is a non-invasive method that provides an average soil moisture for a large support volume (radial footprint up to 240 m, depth up to 80 cm) with high temporal resolution. It covers the most dynamic part of the vadose zone at a scale that is already a more substantial part of the landscape then local point measurements. This integral soil moisture value overcomes the limitations regarding issues of small-scale heterogeneity. Therefore, the use of CRNS soil moisture could improve the estimation of potential groundwater (GW) recharge at the field.

Besides the stochastic integration of point-scale soil moisture profiles, CRNS soil moisture estimates could be used for the inverse estimation of effective soil hydraulic properties by applying unsaturated soil hydrological models and to determine environmental fluxes such as GW recharge.

Within this study CRNS soil moisture is used to estimate the effective soil hydraulic properties within the model HYDRUS 1D. Resulting GW recharge represents the field scale because of the integrated nature of the soil moisture product, even though the model is calculating percolation fluxes for 1D - profiles. These integrated GW recharge fluxes are compared to established point scale methods of GW estimation using soil moisture from a distributed sensor network to inversely estimate the effective soil hydraulic properties within HYDRUS 1D.

CRNS is, however, sensitive to the vertical distribution of water content and this behavior should be explicitly considered. Two approaches are assessed further to account for that. On the one hand, a correction of CRNS, based on measured soil moisture profiles, is tested and CRNS soil moisture is directly used for recharge calculation in HYDRUS. On the other hand, the COSMIC-Operator, as implemented within HYDRUS, is used for calibrating the model by directly comparing neutron count rates from simulated soil moisture. Both approaches are assessed with respect to their ability to estimate natural groundwater recharge rates.

How to cite: Scheiffele, L. M., Munz, M., Baroni, G., Bauer, S., and Oswald, S. E.: Dynamic groundwater recharge rates at field scale: how to successfully use soil moisture from cosmic-ray neutron sensing, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-18563, https://doi.org/10.5194/egusphere-egu2020-18563, 2020.

EGU2020-9020 | Displays | HS1.1.3

Detection of subsurface water storage dynamics with combined gravity - vertical gravity gradient monitoring and hydrological simulation

Anne-Karin Cooke, Cédric Champollion, Pierre Vermeulen, Camille Janvier, Bruno Desruelle, Nicolas Le Moigne, and Sébastien Merlet

Time-lapse ground-based gravimetry is increasingly applied in subsurface hydrology, providing mass balance constraints on water storage dynamics. For a given water content change as e.g. after a precipitation event, the simplest assumption is that of a homogeneous, infinite slab (Bouguer plate) of water column causing the measurable increase in gravitational attraction. For heterogeneous subsurface environments such as karst aquifers at field scale this assumption may not always hold. The gravity signal is depth-integrated and non-unique, hence indistinguishable from a heterogeneous distribution without further information.

Exploiting the different spatial sensitivities of gravity and vertical gravity gradient (VGG) data can shed light on the following questions:

 

  • Is the subsurface water content within the gravimeter’s footprint likely to be homogeneous or showing small-scale heterogeneity?

  • If not, at which distance are these mass heterogeneities and how large are they?

  • Which monitoring set-ups (tripod heights, number of and distance between VGG measurement locations) are likely to detect mass heterogeneity of which spatial characteristics?

One year of monthly vertical gravity gradient surveys has been completed in the geodetic observatory in karstic environment on the Larzac plateau in southern France. We interpret the VGG observations obtained in this field study in the context of further available hydraulic and geophysical data and hydro-gravimetrical simulation. Finally, practical applications in view of detecting near-surface voids and reservoirs of different porosities as well as their storage capacity and seasonal dynamics are evaluated.

How to cite: Cooke, A.-K., Champollion, C., Vermeulen, P., Janvier, C., Desruelle, B., Le Moigne, N., and Merlet, S.: Detection of subsurface water storage dynamics with combined gravity - vertical gravity gradient monitoring and hydrological simulation, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-9020, https://doi.org/10.5194/egusphere-egu2020-9020, 2020.

EGU2020-9522 | Displays | HS1.1.3

Evaluation of NMR and other soil water content measurement methods at the point and field scale

Matteo Bauckholt, Marco Pohle, Martin Schrön, Steffen Zacharias, Solveig Landmark, Susanne Kathage, Andreas Kathage, Carmen Zengerle, Mandy Kasner, and Ulrike Werban

Soil water content in the unsaturated zone is a key parameter of the environmental system. The understanding of soil moisture plays a major role with regard to questions of water and nutrient supply to plants, groundwater recharge, soil genesis and climatic interactions.

In our study we aim to test a new technology for the non-invasive measurement of soil moisture profiles, the so-called Surface-NMR (Nuclear Magnetic Resonance). The instrument applies magnetic fields to the ground and detects its changes caused by mobile and immobile hydrogen atoms in the soil column. Using four different frequencies, the data may provide insights into the water content of four distinct soil layers between the surface and 20 cm depth.

We carried out multiple NMR measurements at four different field sites in Germany and compared the data with conventional methods, such as gravimetric soil samples, Time Domain Reflectometry (TDR), and Cosmic-Ray Neutron Sensing (CRNS).

The dataset will be used to investigate the following research questions:

  1. Is the Surface-NMR method suitable to provide depth-resolved information of soil moisture under field conditions?
  2. Does Surface-NMR have the potential to replace or complement conventional methods of soil moisture measurement in the field?
  3. What can we learn about the spatial variability and scale dependency of soil moisture by combining three measurement methods of different scale (TDR, NMR, CRNS)?

How to cite: Bauckholt, M., Pohle, M., Schrön, M., Zacharias, S., Landmark, S., Kathage, S., Kathage, A., Zengerle, C., Kasner, M., and Werban, U.: Evaluation of NMR and other soil water content measurement methods at the point and field scale, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-9522, https://doi.org/10.5194/egusphere-egu2020-9522, 2020.

EGU2020-1072 | Displays | HS1.1.3

Optimization of ambient seismic noise interferometry to monitor groundwater level variations.

Marco Taruselli, Diego Arosio, Laura Longoni, Monica Papini, and Luigi Zanzi

 In this work, we test the cross-correlation of ambient seismic noise method in monitoring underground water variations. Within this perspective we applied the abovementioned technique to study the water table changes occurring both in areas exploited for drinking water needs and inside landslides. Into detail, surveys were carried out in Crépieux-Charmy and Ventasso water catchment fields and in the Cà Lita landslide, respectively. Our aim is to optimize the outcome of the method by studying the effect of different processing steps involved in the computation of the cross-correlation technique. For this purpose, we analyzed the influence of filter types and different time windows length. Additionally, in order to address the problem of localization of the change in the medium the seismic velocity variations have been also derived from limited frequency bandwidths according to the characteristics observed in the signals spectrum. This work has shown the potential of this methodology as a valuable non-destructive toll to accurately describe hydrogeological dynamics. The monitoring system could thus be coupled with the traditional tools to improve the reconstruction of the underground water variations.

How to cite: Taruselli, M., Arosio, D., Longoni, L., Papini, M., and Zanzi, L.: Optimization of ambient seismic noise interferometry to monitor groundwater level variations., EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-1072, https://doi.org/10.5194/egusphere-egu2020-1072, 2020.

EGU2020-19014 | Displays | HS1.1.3

Observation of gravity fluctuations due to tide-induced groundwater table fluctuations with two superconducting gravimeters

Hiroki Goto, Mituhiko Sugihara, Yuji Nishi, and Hiroshi Ikeda

Estimation of aquifer hydraulic properties is necessary for predicting groundwater flow and hence managing groundwater resources. Analysis of tide-induced groundwater table fluctuations in unconfined aquifers is one of the methods to estimate aquifer properties. Changes in groundwater level affect surface gravity. Consequently, surface gravity in coastal regions is expected to fluctuate due to the groundwater table fluctuations and is potentially useful for estimating aquifer properties. Moreover, gravity measurements are sensitive to mass redistribution around the observation location and therefore are useful for estimating the storage coefficient of an aquifer. In this study, surface gravity and unconfined groundwater level were measured continuously near the coast of Japan to observe gravity fluctuations due to the tide-induced groundwater table fluctuations. Groundwater level measured in two wells at 60 and 90 m distances from the coastline fluctuated in response to ocean tides. Two superconducting gravimeters (SGs) were installed at 70 and 80 m distances from the coastline and at an elevation of 8 m. After taking the difference between gravity values recorded with the two SGs and then correcting the gravity difference for ocean loading effects, diurnal and semi-diurnal gravity fluctuations, which are possibly due to tide-induced groundwater table fluctuations, were recognized. These results suggest that gravity monitoring with two SGs at different distances from the coastline can be useful for observing gravity fluctuations due to tide-induced groundwater table fluctuations and possibly for estimating aquifer hydraulic properties.

How to cite: Goto, H., Sugihara, M., Nishi, Y., and Ikeda, H.: Observation of gravity fluctuations due to tide-induced groundwater table fluctuations with two superconducting gravimeters, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-19014, https://doi.org/10.5194/egusphere-egu2020-19014, 2020.

EGU2020-22370 | Displays | HS1.1.3

Discriminating biomass and soil water content with proximal gamma-ray spectroscopy

Fabio Mantovani, Matteo Albéri, Carlo Bottardi, Enrico Chiarelli, Kassandra Giulia Cristina Raptis, Andrea Serafini, and Virginia Strati

The exceptional capabilities of proximal radiometric measurements to estimate Soil Water Content (SWC) have recently been proven effective for precision farming applications. The water contained in the growing vegetation (i.e. Biomass Water Content, BWC) attenuates the terrestrial gamma signal acquired by a permanent station in a crop field and it represents the most relevant source of systematic bias. In the perspective of employing proximal gamma-ray spectroscopy for automatic irrigation scheduling, the Biomass Water Content (BWC) correction is mandatory for assessing crop water demand and for a sustainable use of water.

In this study we model the time dependent gamma signal attenuation due to BWC and we demonstrate that the SWC estimated through the corrected spectrometric data during a crop life-cycle agrees on average within 4% with the measurements obtained by gravimetric sampling campaigns. A reliable Monte Carlo simulation of the gamma photon generation, propagation and detection phenomena permits to evaluate the shielding effect due to the linear increase of BWC associated to stems, leaves and fruits of the tomatoes during their crop life-cycle. Compared to a SWC gamma estimation in the case of bare soil, the percentage overestimation δ is linearly correlated with the thickness of a biomass equivalent water layer (Tk) as δ (%) = 9.7 · Tk (mm), with a coefficient of determination r2 = 0.99.

Generalizing this approach, we can conclude that the plant growth curve is a fundamental input for correcting the SWC estimates in proximal gamma-ray spectroscopy via Monte Carlo simulation, in the perspective of filling the gap between punctual and satellite soil moisture measurements using this technique.

How to cite: Mantovani, F., Albéri, M., Bottardi, C., Chiarelli, E., Raptis, K. G. C., Serafini, A., and Strati, V.: Discriminating biomass and soil water content with proximal gamma-ray spectroscopy, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-22370, https://doi.org/10.5194/egusphere-egu2020-22370, 2020.

HS1.1.4 – Advances in river monitoring and modelling: data-scarce environments, real-time approaches, Inter-comparison of innovative and classical frameworks, uncertainties, Harmonisation of methods and good practices

EGU2020-5684 | Displays | HS1.1.4 | Highlight

Low-cost river discharge measurements using a transparent velocity-head rod

Aurélien Despax, Jérôme Le Coz, Francis Pernot, Alexis Buffet, and Céline Berni

The common streamgauging methods (ADCP, current-meter or tracer dilution) generally require expensive equipment, with the notable exception of volumetric gaugings and floats, which are however often difficult to implement and limited to specific conditions. The following work aims at testing and validating a reliable, easy-to-deploy and low-cost gauging method, at a cost typically below 40 € each.

The “velocity-head rod” firstly described by Wilm and Storey (1944), made transparent by Fonstad et al. (2005) and improved by Pike et al. (2016) meets these objectives, for wading gauging with velocities greater than 20 cm/s typically. The 9.85 cm wide clear plastic rod is placed vertically across the stream to identify upstream and downstream water levels using adjustable rulers. The difference in level (or velocity head) makes it possible to calculate the average velocity over the vertical, using a semi-empirical calibration relationship.

Experiments carried out in INRAE’s hydraulic laboratory and in the field have enabled us to find a calibration relationship similar to that proposed by Pike et al. (2016) and confirm the optimal conditions of use. The average deviation to a reference discharge has been found to be close to 5 % except for very slow-flow conditions. The influence of the width of the rod on the velocity-head was studied in the laboratory. The uncertainty of the velocity due to the reading of water levels has been estimated. It increases at low velocity due to decreasing sensitivity, and increases at high velocities due to water level fluctuations that are difficult to average.

Several improvements were tested in order to facilitate and improve the measurement operations, without increasing the cost too much: magnetic ruler, removal of a graduated steel rule (expensive), plastic ruler with water level and velocity graduations, reading the depth with another ruler, spirit level, electrical contact (so the operator has not to bend to the surface of the water). An operational procedure and a spreadsheet for computing discharge are proposed. The method being extremely simple and quick to apply is well suited for rapid estimates of flow (instead of floats), training or demonstrations, citizen science programs or cooperation with services with limited resources.

Acknowledgments: The authors thank Q. Morice, J. Cousseau, Y. Longefay (DREAL) who were involved in this study by carrying out field tests.

How to cite: Despax, A., Le Coz, J., Pernot, F., Buffet, A., and Berni, C.: Low-cost river discharge measurements using a transparent velocity-head rod, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-5684, https://doi.org/10.5194/egusphere-egu2020-5684, 2020.

EGU2020-9943 | Displays | HS1.1.4

Wind effect on image-based river surface velocity measurements

Salvador Peña-Haro, Beat Lüthi, Robert Lukes, and Maxence Carrel

Image-based methods for measuring surface flow velocities in rivers have several advantages, one of them being that the sensor (camera) is not in contact with the water and its mounting position is very flexible hence there is no need of expensive structures to mount it. Additionally, it is possible to measure the whole river width. On the other hand, environmental factors, like wind, can affect the surface velocity and the have an impact on the accuracy of the measurements.

Herein we present an analysis of the wind effect on the image based surface velocity at Rhine river, at the border between Switzerland and Austria. At this location the river width is of approximately 100 meters under low flow conditions, while the width of its floodplain is of about 200 m. An ATMOS 22 ultrasonic anemometer was installed at the site to measure the wind intensity as well as its direction.

A time series of flow velocities and wind from May to October 2019 was analyzed. During this period, the average discharge was 320 m3/s and the average flow velocity 1.7 m/s. While the average wind velocity was of 2.3m/s which roughly follows the same direction of the river flow.

A rating curve following a power law function was fitted to the image based surface flow measurements. It was found that for maximum wind speeds of 10 m/s, blowing in the opposite direction of the river flow, there was a deviation of 8%. For the average wind speed of 2.3m/s, the deviation was found to be 3%.

How to cite: Peña-Haro, S., Lüthi, B., Lukes, R., and Carrel, M.: Wind effect on image-based river surface velocity measurements, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-9943, https://doi.org/10.5194/egusphere-egu2020-9943, 2020.

EGU2020-10659 | Displays | HS1.1.4

UAV-based training for fully fuzzy classification of Sentinel-2 fluvial scenes

Patrice Carbonneau, Barbara Belletti, Marco Micotti, Andrea Casteletti, Stefano Mariani, and Simone Bizzi

In current fluvial remote sensing approaches, there exists a certain dichotomy between the analysis of small channels at local scales which is generally done with airborne data and the analysis of entire basins at regional and national scales with satellite data. One possible solution to this challenge is to use low-altitude imagery from low-cost UAVs to provide sub-metric scale class information which can then be used to train fuzzy classification models for entire Sentinel 2 tiles. The fuzzy classification approach can allow for sub-pixel information and when extended to entire Sentinel 2 tiles, the method therefore develops information at a resolution of less than 10 meters (the best spatial resolution of Sentinel 2 bands) at regional scales. In this contribution, we present such a method where UAV imagery is used as the training data for the fully fuzzy classification of Sentinel 2 imagery. We partition the fluvial corridor in three simple classes: water, dry sediment and vegetation.  Then we manually classify the local UAV imagery into highly accurate class rasters. In order to augment the value of the Sentinel 2 data, we use an established super-resolution method that delivers 10 meter spatial resolution across all 11 Sentinel 2 bands. We then use the sub-metric UAV classifications as training data for the 10 meter super-resolved Sentinel 2 imagery and we train fuzzy classification models using random forests, dense neural networks and convolutional neural networks (CNN). We find that CNN architectures perform best and can predict class membership within a pixel of a new Sentinel 2 tile not seen in the training phase with a mean error of 0% and an RMS error of 18%. Crisp class predictions derived from the fuzzy models range in accuracy from 88% to 99%, even in the case of tiles never seen in the training phase. With this approach, it is now possible to deploy a low-cost UAV in order to train a transferable CNN model that can predict fuzzy classes at very large scales from freely available Sentinel 2 imagery. This approach can therefore serve as the basis for multi temporal classification and change detection of the Sentinel 2 archives.

How to cite: Carbonneau, P., Belletti, B., Micotti, M., Casteletti, A., Mariani, S., and Bizzi, S.: UAV-based training for fully fuzzy classification of Sentinel-2 fluvial scenes, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-10659, https://doi.org/10.5194/egusphere-egu2020-10659, 2020.

Environmental Flow Release monitoring can be an expensive undertaking in active watercourses normally suitable for run-of-river hydropower projects.  In order to attain acceptable (<10%) uncertainty in the derived flow series, it is necessary for a Qualified Professional (QP) to make several site visits to measure a range of flows in order to calibrate a stage-discharge (rating) curve.  With climate change, the need to measure drought conditions and respond appropriately is crucial for habitat health and to prevent fish stranding.  The current study employs a Water Quality Mixing Model (WQMM) to estimate flows at a downstream site from an existing hydropower plant using a modified constant rate mixing model.  This is an independent estimate of flow entirely distinct from the stage-discharge curve.  The method can be employed anywhere there is a sufficient mixing length and sufficiently distinct WQ traits.  The method can reduce both maintenance costs and flow uncertainty where Environmental Flow Release Monitoring is required.

How to cite: Sentlinger, G.: Water Quality Mixing Model (WQMM) for Environmental Flow Release Monitoring, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-11759, https://doi.org/10.5194/egusphere-egu2020-11759, 2020.

EGU2020-13832 | Displays | HS1.1.4

Uncertainty quantification of continuous streamflow monitoring in high elevation Alpine catchments

Florentin Hofmeister, Brenda Rubens Venegas, Markus Disse, and Gabriele Chiogna

Correct streamflow measurements are of fundamental importance for hydrology. Mountain catchments are particularly complex systems to obtain reliable discharge time series and several challenges have to be overcome. For example, turbulent flow of mountain streams leads to unstable streambed conditions by erosion and sedimentation and the irregular stream profile makes any streamflow measurements through the velocity-area method difficult. The salt dilution method provides reliable streamflow estimation for specific injection times. We can construct rating curves when these and river stage data are available. However, this relationship entails intrinsic uncertainties that derive from experimental errors as well as from extrapolation outside the measured range. In this work, we provide a rigorous quantification of the uncertainty of discharge measurement based on rating curves using error propagation techniques. During multiple field campaigns in 2019, we collected 74 streamflow measurements for nine sites over three high Alpine catchments (Horlachtal, Kaunertal and Martelltal). We then consider also continuous measurements of water level, water temperature and electrical conductivity. The aim is not only to get more information about the hydrological processes and response of these catchments but also to use this information to construct more robust and less uncertain rating curves. Our results show the high uncertainty affecting measured discharges in Alpine catchments and they are relevant for model applications as well. In fact, the uncertainty in river discharge observations affects the optimal value of the model objective function (e.g., Nash-Sutcliff Efficiency).

How to cite: Hofmeister, F., Rubens Venegas, B., Disse, M., and Chiogna, G.: Uncertainty quantification of continuous streamflow monitoring in high elevation Alpine catchments, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-13832, https://doi.org/10.5194/egusphere-egu2020-13832, 2020.

EGU2020-18413 | Displays | HS1.1.4 | Highlight

Continuous measurement of open channel discharge using a video data logger and subsequent LSPIV analysis

Peter Eichendorff and Andreas Schlenkhoff

Accurate flow data form the basis for describing hydrological runoff processes and extremes. While the continuous measurement of the water level is a standard task in hydrometry, the continuous measurement of flow velocity is more complex and often involves greater effort. Videometric methods like LSPIV (Large Scale Particle Image Velocimetry) allow a contactless acquisition of surface velocity distribution in open channels. Ready-to-use instrumentation for that purpose is hardly available and requires permanent electricity supply.
Therefore, a simple self-made measuring system, consisting of a data logger with camera and a distance sensor, is introduced. It enables not only the detection of the water level but also the recording and remote transmission of video data. Based on an Arduino microcontroller and a Raspberry Pi Single Board Computer the battery-powered data logger is freely programmable with open source software and supports the operation of various sensors with digital interface at low power consumption. 
The measuring system with its wide angle camera is intended to be mounted on bridges or steep banks with longitudinal or transverse to flow camera alignment. The water level is detected by an ultrasonic range transducer, a raspberry pi camera module with wide angle lens records videos in 1080p resolution.  The water level data and the videos are remotely transmitted via cellular network to a server that provides the data to the subsequent LSPIV analysis. The LSPIV analysis enables a high-resolution measurement of the velocity distribution at the water surface and in combination with the known channel geometry and the height of the water level it offers an accurate discharge determination.
Particularly with regard to extreme events the use of video data brings considerable advantages as it allows a visual on-site inspection of the situation. Information such as the condition of the local vegetation, icing or disturbing influences at the gauge site can be derived and included in the flow rate determination.

How to cite: Eichendorff, P. and Schlenkhoff, A.: Continuous measurement of open channel discharge using a video data logger and subsequent LSPIV analysis, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-18413, https://doi.org/10.5194/egusphere-egu2020-18413, 2020.

EGU2020-21652 | Displays | HS1.1.4 | Highlight

Use of Unmanned Aerial Systems for Hydrological Monitoring

Salvatore Manfreda and the HARMONIOUS TEAM

Unmanned Aerial Systems (UAS) are offering an extraordinary opportunity to improve our ability to monitor river basins. The wide use of UAS leaded to a significant grow of the number of applications and methodologies developed for specific scopes of environmental monitoring. For this reason, there is a serious challenge to harmonise and provide standardised guidance applicable across a broad range of environments and conditions. In this context, a network of scientists is cooperating within the framework of a COST (European Cooperation in Science and Technology) Action named “Harmonious - Given the wide use of UAS within environmental studies”. The intention of “Harmonious” is to promote monitoring strategies, establish harmonised monitoring practices, and transfer most recent advances on UAS methodologies to others within a global network. The working groups of Harmonious are currently working on the definition of practical guidance for environmental studies identifying critical processes and the interconnection of each step for a successful workflow. Given the number of environmental constraints and variables, it is impractical to provide a protocol that can be applied universally under all possible conditions, but it is possible to systematise the fragmented knowledge on this topic identifying the best-practices to improve the overall quality of the final products. Preliminary results of the HARMONIOUS COST Action will be given.

How to cite: Manfreda, S. and the HARMONIOUS TEAM: Use of Unmanned Aerial Systems for Hydrological Monitoring, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-21652, https://doi.org/10.5194/egusphere-egu2020-21652, 2020.

EGU2020-324 | Displays | HS1.1.4

An evaluation of image velocimetry techniques under low flow conditions and high seeding densities using Unmanned Aerial Systems

Sophie Pearce, Robert Ljubicic, Salvador Pena-Haro, Matthew Perks, Flavia Tauro, Alonso Pizarro, Silvano Fortunato Dal Sasso, Dariia Strelnikova, Salvatore Grimaldi, Ian Maddock, Gernot Paulus, Jasna Plavsic, Dusan Prodanovic, Salvatore Manfreda, Mark Corbett, and Nick Everard

Image velocimetry (IV) is a remote technique which calculates surface flow velocities of rivers (or fluids) via a range of cross-correlation and tracking algorithms. IV can be implemented via a range of camera sensors which can be mounted on tri-pods, or Unmanned Aerial Systems (UAS). IV has proven a powerful technique for monitoring river flows during flood conditions, whereby traditional in-situ techniques would be unsafe to deploy. However, little research has focussed upon the application of such techniques during low flow conditions. The applicability of IV to low flow studies could aid data collection at a higher spatial and temporal resolution than is currently available. Many IV techniques are under-development, that utilise different cross-correlation and tracking algorithms, including, Large Scale Particle Image Velocimetry (LSPIV), Large Scale Particle Tracking Velocimetry (LSPTV), Optical Tracking Velocimetry (OTV), Kanade Lucas Tomasi Image Velocimetry (KLT-IV) and Surface Structure Image Velocimetry (SSIV). Nevertheless, the true applications and limitations of such algorithms have yet to be extensively tested. Therefore, this study aimed to conduct a sensitivity analysis on the commonly relatable parameters between the different algorithms, including the particle identification area parameters (such as Interrogation Area (LSPIV, LSPTV and SSIV), Block Size (KLT-IV) and Trajectory Length (OTV)) and the feature extraction rate (or sub sampled frame rate).

Fieldwork was carried out on Kolubara River near the city of Obrenovac in Central Serbia. Cross-sectional surface width was relatively constant, varying between 23.30 and 23.45m. During the experiment, low flow conditions were present with a discharge of approx. 3.4m3 s-1 (estimated using a Sontek M9 ADCP), and depths of up to 1.9m. A DJI Phantom 4 Pro UAS was used to collect video data of the surface flow. Artificial seeding material (wood-mulch) was distributed homogenously across the rivers’ surface, in order to improve the conditions for IV techniques during slow flows. Two 30-second videos were utilised for surface velocity analysis.

This study highlighted that KLT, SSIV, OTV and LSPIV are the least sensitive algorithms to changing parameters when no pre- or post-processing of results are conducted. On the other hand, LSPTV must undergo post-processing procedures in order to avoid spurious results and only then, results may be reliable. Furthermore, KLT and SSIV highlighted a slight sensitivity to changing the feature extraction rate, however changing the particle identification area did not affect significantly the outputted surface velocity results. OTV and LSPTV, on the other hand, highlighted that changing the particle identification area provided a higher variability in the results, whilst changing the feature extraction rate did not affect the surface velocity outputs. LSPIV proved to be sensitive to changing both the feature extraction rate and the particle identification area.

This analysis has led to the conclusions that during the conditions of sampling with surface velocities of approximately 0.12ms-1, and homogeneous seeding on the rivers surface, IV techniques can provide results comparable to traditional techniques such as ADCPs during low flow conditions. All IV algorithms provided results that were, on average, within 0.05ms-1 of the ADCP measurements.

 

How to cite: Pearce, S., Ljubicic, R., Pena-Haro, S., Perks, M., Tauro, F., Pizarro, A., Fortunato Dal Sasso, S., Strelnikova, D., Grimaldi, S., Maddock, I., Paulus, G., Plavsic, J., Prodanovic, D., Manfreda, S., Corbett, M., and Everard, N.: An evaluation of image velocimetry techniques under low flow conditions and high seeding densities using Unmanned Aerial Systems, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-324, https://doi.org/10.5194/egusphere-egu2020-324, 2020.

EGU2020-4229 | Displays | HS1.1.4 | Highlight

A drone-borne contactless method to jointly estimate discharge and Manning’s roughness in rivers

Filippo Bandini, Beat Lüthi, Salvador Peña-Haro, and Peter Bauer-Gottwein

Unmanned Aerial Systems (UASs) can monitor streams and rivers also in remote, inaccessible locations during extreme hydrological events. Image cross-correlation analysis techniques, such as Particle Image Velocimetry (PIV), applied to videos acquired using UASs can provide estimates of water surface velocity (WSV) in rivers. However, estimation of discharge from WSV is not trivial: it requires water depth and the mean vertical velocity (Um). Scientific studies show that Um is generally between 70% and 90% of WSV; however, an accurate estimation of Um from WSV requires assumptions on the full vertical velocity profile. We developed a new method for estimating WSV applying PIV techniques on UAS-borne videos. This method does not require any Ground Control Point (GCP), because the conversion of the velocity field from pixels into meters is performed by using a camera pinhole model where the distance from the pin-hole to the water surface is measured by an on-board radar altimeter. For approximately uniform flow conditions, Um becomes a function of Gauckler–Manning–Strickler roughness coefficient (Ks) and WSV. Our method can be used to jointly estimate Ks and discharge by informing a non-linear system of 2 equations and 2 unknowns (Ks and discharge): i) Manning equation ii) mid-section method equation for computing discharge from Um, which is a function of WSV and ks. This approach merely relies on bathymetry knowledge, on UAV-borne measurements of WSV and water surface slope.  Our approach was extensively validated in 27 case studies, in multiple Danish streams with different hydraulic conditions. Compared to discharge measured with a multi-depth electromagnetic velocity probe, PIV-estimates of discharge showed a mean absolute error of 18% and a mean bias error of -9%. The underestimation of discharge is caused by inaccuracies in WSV, by deviations from the uniform flow assumption and by the assumption of constant Ks coefficient for the entire cross section.

How to cite: Bandini, F., Lüthi, B., Peña-Haro, S., and Bauer-Gottwein, P.: A drone-borne contactless method to jointly estimate discharge and Manning’s roughness in rivers , EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-4229, https://doi.org/10.5194/egusphere-egu2020-4229, 2020.

EGU2020-4661 | Displays | HS1.1.4

Uncertainty of discharge measurement using salt dilution

Alexandre Hauet, Kristoffer Florvaag-Dybvik, Mads-Peter Jakob Dahl, Frode Thorset Kvernhaugen, Knut Magne Møen, and Gabriel Sentlinger

Discharge measurement using salt dilution is an old method, but it has been recently more and more used thanks to the development of new sensors making it possible to measure conductivity and compute discharge in real-time. Salt dilution is very well suited for turbulent rivers, such as mountain streams. The ISO standard ISO 9555 propose a normative framework to estimate uncertainty, but it was published in 1994 and is now obsolete for new sensors and computational capabilities. In this article, we propose a complete framework to compute the uncertainty of a salt dilution gauging following the GUM (Guide to the expression of uncertainty in measurement) method that take into account the following error sources:  (i) the uncertainty in the mass of salt injected, (ii)  the uncertainty in the measurement of time, (iii) the uncertainty in the Conductivity to Concentration law, (iv) the uncertainty if a measurement conductivity is out of the range of the Conductivity to Concentration law, (v) the uncertainty in the computation of the area under the conductivity curve, (vi) the uncertainty due to a not perfect mixing of the tracer if the mixing length between injection and the probes is not reached (vii) the uncertainty due to a loss or a gain of tracer between the injection and the probes if tracer can be adsorbed for example and (viii) the uncertainty due to unsteadiness of the flow  i.e. variation of discharge during the measurement. The method for computing each uncertainty source is presented and the new framework is applied to a set of real measurements and compared to the expertise of field hydrologists.

How to cite: Hauet, A., Florvaag-Dybvik, K., Dahl, M.-P. J., Kvernhaugen, F. T., Møen, K. M., and Sentlinger, G.: Uncertainty of discharge measurement using salt dilution , EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-4661, https://doi.org/10.5194/egusphere-egu2020-4661, 2020.

EGU2020-6779 | Displays | HS1.1.4 | Highlight

Comparison of rating-curve uncertainty estimation using hydraulic modelling and power-law methods

Ida Westerberg, Valentin Mansanarez, Steve Lyon, and Norris Lam

Establishing reliable rating curves and thereby reliable streamflow monitoring records is fundamental to much of hydrological science and water management practice. Cost-effective methods that enable rapid rating curve estimation with low uncertainty are needed given diminishing monitoring resources and increasing human-driven changes to the water cycle. Traditional power-law rating curves rely on numerous gaugings to estimate rating curves and their associated uncertainty. Hydraulically-modelled rating curves are a promising alternative to power-law methods as they rely on fewer gaugings, but they are associated with additional uncertainty sources in the hydraulic knowledge (bed slope, roughness, topography and vegetation), which need to be assessed.

Our aim with this study was to compare power-law and hydraulic-model based methods for estimating rating curves and their uncertainty. We focused on assessing their accuracy as well as the costs and time required for establishing rating curves. We compared the Rating curve Uncertainty estimation using Hydraulic Modelling (RUHM) framework with the Bayesian power-law method BaRatin. The RUHM framework combines a one-dimensional hydraulic model with Bayesian inference to incorporate information from both hydraulic knowledge and the calibration gauging data. We applied both methods to the 584 km2 River Röån station in Sweden under nine different gauging strategies associated with different costs. The gauging strategies differed in the number and flow magnitude of the gaugings used as well as the probability of observing the gauged flows.

We found that rating curves with low uncertainty could be modelled with fewer gaugings using the RUHM framework compared to BaRatin. As few as three gaugings were needed for RUHM if these gaugings covered low and medium flows, making the estimation both cost effective and time efficient. When using all the gaugings available (i.e. a high-cost gauging strategy), the uncertainty for RUHM and BaRatin was similar at the Röån station. Furthermore, we found that BaRatin needed gaugings with lower probability of occurrence (i.e. covering a larger part of the flow range) than needed when using hydraulic modelling (low and middle flow gaugings with high probability of occurrence gave good results). The results for this Swedish site show that hydraulic rating curve uncertainty estimation is a promising tool for quickly estimating rating curves and their uncertainties. In particular, it is useful for previously ungauged or remote sites, or at stations where there have been major temporal changes to the stage–discharge relation.

How to cite: Westerberg, I., Mansanarez, V., Lyon, S., and Lam, N.: Comparison of rating-curve uncertainty estimation using hydraulic modelling and power-law methods, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-6779, https://doi.org/10.5194/egusphere-egu2020-6779, 2020.

EGU2020-8890 | Displays | HS1.1.4

Impacts of water resources management on the North China Plain revealed in multi-mission earth observation datasets

Jun Liu, Liguang Jiang, Filippo Bandini, Xingxing Zhang, and Peter Bauer-Gottwein

The natural conditions of surface water bodies and groundwater aquifers in many densely populated river basins have been altered in order to satisfy various human water demands, such as drinking water supply, irrigation, power generation and navigation. The North China Plain (NCP) accounts for about 24% of the country's population, and the huge water demand makes it one of the regions with the strongest artificial intervention in the water cycle. China has promoted the South-to-North Water Diversion (SNWD), which diverts surplus water from the Yangtze River Basin to the water-deficient North. Since the central line project of SNWD has become fully operational in 2014, more than 16 km3 of water have been supplied to the NCP, which has had a significant impact on water resources in the regions along the route. Monitoring the recent dynamics of surface and sub-surface water storage is essential for water resources management and sustainable use of ongoing and forthcoming SNWD water transfers. Multi-mission satellite earth observation methods provide timely and spatially resolved datasets for monitoring inland water bodies, which have been validated over the last two decades. In this study, first, we evaluate the influence of SNWD on the Terrestrial Water Storage (TWS) monitored by the Gravity Recovery and Climate Experiment (GRACE) and its follow-on mission (GRACE-FO) over the NCP. The results indicate that the significant downward trend during 2002 – 2014 period, has stopped in the past 5 years, since the implementation of the central line project of SNWD. Second, Sentinel-3 radar altimetry and Sentinel-1 SAR missions were used to monitor the water surface extent and water surface elevation of surface water bodies. Sentinel-1 with its newly available Synthetic Aperture Radar (SAR), high spatial resolution and short temporal baselines shows potential for monitoring surface water area variations. Sentinel-3 benefits from the new Sentinel Ku/C Radar Altimeter (SRAL) and a modified on-board tracking system and shows great potential for monitoring inland water surface elevation (WSE) variations for several large and medium reservoirs and canals in this region. We show that, along with other policy measures, the SNWD transfers have had a significant impact on the water balance of the NCP region as evident from multiple satellite earth observation missions.

How to cite: Liu, J., Jiang, L., Bandini, F., Zhang, X., and Bauer-Gottwein, P.: Impacts of water resources management on the North China Plain revealed in multi-mission earth observation datasets, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-8890, https://doi.org/10.5194/egusphere-egu2020-8890, 2020.

EGU2020-15525 | Displays | HS1.1.4

Image-velocimetry techniques under particle aggregation for streamflow monitoring: a numerical approach

Alonso Pizarro, Silvano Fortunato Dal Sasso, and Salvatore Manfreda

Monitoring extreme events with high accuracy and consistency is still a challenge, even by using up-to-date approaches. On the one side, field campaigns are in general expensive and time-consuming, requiring the presence of high-qualified personnel and forward planning. On the other side, non-contact approaches (such as image velocimetry, radars, and microwave systems) have had promising signs of progress in recent years, making now possible real-time flow monitoring. This work focuses on the estimation of surface flow velocities for streamflow monitoring under particle aggregation, in which tracers are not necessarily uniformly distributed across the entire field of view. This issue is extremely relevant for the computing stream flows since velocity errors are transmitted to river discharge estimations. Ad-hoc numerical simulations were performed to consider different levels of particle aggregation, particle colour and shapes, seeding density, and background noise. Particle Tracking Velocimetry (PTV) and Large-Scale Particle Image Velocimetry (LSPIV) were used for image velocimetry estimations due to their widely used worldwide. Comparisons between the theoretical and computed velocities were carried out to determine the associated uncertainty and optimal experimental setup that minimises those errors.

How to cite: Pizarro, A., Dal Sasso, S. F., and Manfreda, S.: Image-velocimetry techniques under particle aggregation for streamflow monitoring: a numerical approach, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-15525, https://doi.org/10.5194/egusphere-egu2020-15525, 2020.

EGU2020-16011 | Displays | HS1.1.4

On the characterisation of open-flow seeding conditions for image-velocimetry techniques using UASs

Silvano Fortunato Dal Sasso, Alonso Pizarro, and Salvatore Manfreda

In the last years, new technologies have been developed to monitor rivers in a real-time framework opening new opportunities and challenges for the research community and practitioners. Acquiring data in open flow conditions can be performed through the use of Unmanned Aerial System (UAS) to derive surface velocity fields and in consequence, river discharge. Significant work has been done to investigate the reliability of image-velocimetry techniques using numerical simulations and laboratory flume experiments, but, to date, the effects of environmental factors on velocity estimates are not addressed adequately. In this context, a critical variable is represented by the number of particles transiting on the water surface (defined as seeding density) during field surveys and their challenging dynamics along the cross-section, on both time and space. Seeding density has a significant effect on surface velocity estimation and river discharge accuracy. The goal of this study was, therefore, to evaluate the accuracy and feasibility of LSPIV and PTV techniques under different seeding and flow conditions using several footages acquired employing UASs. To this purpose, the seeding behaviour during the whole acquisition time was examined for each case study focusing on the quantification of essential variables such as seeding density, average tracers’ dimension, coefficient of variation of tracers’ area, and spatial dispersion of them in the field of view. For each case study, both image-velocimetry techniques have been applied considering several different sets of images to locally measure the accuracy of velocity estimations in challenging seeding conditions. Results show that the local seeding density, tracers’ dimension and their spatial distribution can strongly influence the reconstruction of velocity fields in natural stream reaches. Therefore, prior knowledge of seeding characteristics in the field can deal with the choice of the optimal image-velocimetry technique to use and the related setting parameters.

How to cite: Dal Sasso, S. F., Pizarro, A., and Manfreda, S.: On the characterisation of open-flow seeding conditions for image-velocimetry techniques using UASs , EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-16011, https://doi.org/10.5194/egusphere-egu2020-16011, 2020.

We introduce a Python based software tool to measure surface flow velocities and to estimate discharge eventually. Minimum needed input are image sequences, some camera parameters and object space information to scale the image measurements. Reference information can be provided either indirectly via ground control point measurements or directly providing camera pose parameters. To improve the reliability and density of velocity measurements the area of interest has to be masked for image velocimetry. This can either be performed with a binary mask file or considering a 3D point cloud, for instance retrieved with Structure from Motion (SfM) photogrammetry, describing the region of interest. The tracking task can be done with particle image velocimetry (PIV) considering small interrogation regions or using particle tracking velocimetry (PTV) and thus detecting and tracking features at the water surface. To improve the robustness of the tracking results, filtering can be applied that implements statistical information about the flow direction, flow steadiness and average velocities.

The FlowVeloTool has been tested with two different datasets; one at a gauging station and one at a natural river reach. Thereby, UAV and terrestrial data were acquired and processed. Velocities can be estimated with an accuracy of 0.01 m/s. If information about the river topography and bathymetry are available, as in our demonstration, discharge can be estimated with an error ranging from 5 to 31 % (Eltner et al. 2019). Besides these results we demonstrate further developments of the FlowVeloTool regarding filtering of tracking results, discharge estimation, and processing of time series. Furthermore, we illustrate that thermal data can be used, as well, with our tool to retrieve river surface velocities.

 

Eltner, A., Sardemann, H., and Grundmann, J.: Flow velocity and discharge measurement in rivers using terrestrial and UAV imagery, Hydrol. Earth Syst. Sci. Discuss., https://doi.org/10.5194/hess-2019-289, 2019.

How to cite: Eltner, A. and Grundmann, J.: FlowVeloTool: Measuring flow velocities in terrestrial and UAV image sequences automatically with PIV and PTV, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-17773, https://doi.org/10.5194/egusphere-egu2020-17773, 2020.

There is growth in evidence of intensification of the global hydrological cycle over the past few decades, possibly due to changing climate and/or land-use landcover associated with anthropogenic forcing. For sustainable water management, an efficient and effective streamflow network is essential as it facilitates accurate monitoring of spatio-temporal variations of surface water. However, in recent years a remarkable decline in stream gauge density is observed in both developed and developing countries, possibly due to economic constraints and changing government priorities. World Meteorological Organization recommends periodic reviewal of stream gauge networks (accounting for changes in budgetary, data and end user’s needs) to improve the database for better assessment of hydrological uncertainty. However, there is a dearth of such attempts in India. Entropy theory (specifically Shannon entropy-based method (SEBM)) has gained wide recognition over the past few decades for the optimal design of hydrometric networks owing to its advantages. However, the SEBM has some limitations, which include (i) lack of fixed upper bound for entropy when a uniform distribution is considered to determine the probability and (ii) loss of information due to discretization of data in analysis with continuous variables. In this backdrop, there is a need to locate feasible alternatives to the Shannon entropy method. There are various methods for entropy estimation and data discretization, but there is a lack of information on their relative performance. This study is envisaged to investigate these aspects and to propose a novel fuzzy approach for optimal design and performance assessment of a stream gauge monitoring network. The proposed methodology does not require the choice of bin size for the discretization of data to estimate entropy measures/indices. Therefore, it alleviates the associated uncertainty which is a concern in analysis with SEBM and its related theoretical improvement EEBM (exponential entropy-based methodology). This is demonstrated through case studies on 16 river basins of Peninsular India encompassing more than 600,000 km2 by considering objectives as prioritization of existing gauges, identification of gauge deficient zones and devising options for expansion of the existing stream gauge networks. Further, the effect of choice of bin size on entropy estimates obtained using SEBM and EEBM is demonstrated by considering nine bin size determination methods. Flows in ungauged catchments were simulated using SWAT (Soil and Water Assessment Tool) and optimization of the existing stream gauge network is performed using a Fast-Non-Dominated Sorting Genetic Algorithm (NSGA-II). The study indicated that all the stream gauge networks in peninsular India are inadequate for effective monitoring of flows and there is a growing need for their expansion.  This study is first of its kind which evaluates the potential of different entropy-based methods in stream gauge network design. The proposed methodology could be readily considered for the evaluation of networks monitoring other hydro-meteorological and hydrological variables, and water quality parameters.

How to cite: Vijay, S.: A Comparative Study of Entropy-based Methods for Optimal Design of Streamgauge Monitoring Networks, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-398, https://doi.org/10.5194/egusphere-egu2020-398, 2020.

Previous studies have established the ability to map river channel bathymetry accurately in clear water, shallow wadeable streams using imagery from Unmanned Aerial Vehicles (UAVs), Structure-from-Motion (SfM) photogrammetry and the application of refraction correction. However, because standard rotary-winged UAVs geotag imagery at a relatively low accuracy, there has been a need to use Ground Control Points (GCPs) to georeference the Digital Elevation Model (DEM). This is problematic in that is requires the operators to navigate around the site to place, survey and collect the GCPs which can be very time consuming and/or hazardous. A potential solution lies with the recent introduction of lower cost rotary-winged drones fitted with higher accuracy on-board RTK GPS sensors. These have raised the possibility of conducting UAV surveys with the use of very few or no GCPs across the survey site, saving time and removing the need to access all areas for GCP placement.

To test this possibility, we flew a 250 metre reach of the River Teme (max depth ~1m) on the English-Welsh border at 40m in July 2019 with two drones, i.e. a DJI Phantom 4 RTK UAV and base station and a DJI Phantom 4 PRO (non-rtk). The Phantom 4 RTK UAV was flown three times, i) using the flight program’s 2D option (nadir only and one flight path) ii) using the 3D option (camera angled at 60° and flown in two directions) and iii) using the RTK off option and then using post-processing (PPK) to correct the image locations. 20 GCPs were placed across the site and their locations surveyed with a Trimble R8 dGPS and an additional 20 Independent Validation Points (IVPs) were surveyed along the floodplain for terrestrial validation points and 100 points within the channel were surveyed submerged area validation points.

Imagery was processed with Agisoft Metashape (v1.5.5). A total of 28 DEMs were produced using the imagery from the two drones, different flight paths and different combinations of numbers and location of GCPs. These included reducing the number of GCPs from 20, to 10, 5, 3, 1 and 0. When using three GCPs, DEMs were produced by having them i) spread throughout the reach and ii) clustered close to one another. The bed heights of the submerged locations were corrected using the simple refraction correction first used by Westaway et al (2001) and then compared to the measured heights in the field. Accuracy was quantified using linear regression.

The results of this analysis demonstrated the ability to obtain accurate surveys of bathymetry in depths upto 1m using a DJI Phantom 4 RTK UAV and base station and a significantly reduced number of GCPS, combined with the application of refraction correction. This study confirms that considerable time saving in terms of fieldwork can be gained from the use of an RTK rotary-winged drone and base station. This technology can also be beneficial for obtaining accurate survey data in locations where it may be unsafe or impossible to place GCPs due to the hazardous nature of the terrain.

How to cite: Maddock, I. and Lynch, J.: Assessing the accuracy of river channel bathymetry measurements using an RTK rotary-winged Unmanned Aerial Vehicle (UAV) with varying Ground Control Point (GCP) number and placement, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-1534, https://doi.org/10.5194/egusphere-egu2020-1534, 2020.

In this research, we conducted LSPIV (Large Scale Particle Image Velocimetry) measurements to measure river surface velocity based on images recorded by mobile phone. The realization of this research is based on the developments of two products. The first one is the digital camera, which has been combined with the mobile phone after several years of development. The second one is the three-axis accelerometer, which can measure the attitude of the object. A three-axis accelerometer is one of the necessary parts of the mobile phone nowadays, as many functions of the mobile phone, such as step counting, Do Not Disturb mode, games, require the detection of attitude.

In LSPIV, there are nine parameters of the collinear equation. Three of parameters are the coordinates of the perspective center in the image space (focus distance d and image center position (u, v)), which can be determined in advance in the laboratory; the other three parameters are the coordinates (x, y, z) of the perspective center in real space, which can be set to (0, 0, 0); the last three parameters are the attitude of the camera (i.e., the mobile phone), which is determined by the depression angle, the horizontal angle, and the left-right rotation angle and can be measured by three-axis accelerometer. Therefore, river surface velocity could be analyzed by LSPIV with not only continuous images captured by a camera of the mobile phone but also the acceleration values obtained by the three-axis accelerometer when each image was captured.

In the present study, Yufeng gauging station, which is in the upstream catchment of the Shihmen Reservoir in Taiwan, is selected as the study site. Two other measurement methods were used to measure the river surface velocity and the comparison was conducted. One is using a handheld digital flow meter and another is using LSPIV with control points to calculate the parameters for measuring the river surface velocity.

How to cite: Liu, W.-C. and Huang, W.-C.: Large scale particle image velocimetry measurement of river surface velocity based on images captured by a camera of the mobile phone, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-1760, https://doi.org/10.5194/egusphere-egu2020-1760, 2020.

Robust predictions and forecasts of flood risks and hazards are reliant on accurate estimates of stream flow data.  However, the stage-discharge relationship is subject to substantial uncertainties from a range of error sources, particularly for out-of-bank flows where measurements are scarce and flows are often extrapolated.  Hydraulic modelling can be used to produce more reliable stage–discharge relationships beyond the range of observed measurements, but, these methods are often data intensive requiring topographical, bathymetric, calibration data etc. restricting their use across large samples of gauges.    

In this study, we present an automatable framework that can estimate out-of-bank discharge uncertainty using a hydrodynamic model and readily available national datasets.  The framework utilises LiDAR data, in-bank stage-discharge measurements and gauged river flows to calibrate a 1D/2D hydrodynamic model (LISFLOOD-FP) of a river reach and make predictions of river flow and rating curve uncertainty beyond bankfull.  A particularly novel aspect of this framework is the use of national LiDAR datasets of water surface elevation returns to estimate the bathymetry and friction in the channel using an inversion solver. 

The framework was applied to produce models of two gauged river reaches in the UK, the River Severn at Montford in Shropshire, and the River Tweed at Norham in Northumberland. Bathymetry estimates were consistent with observations, considering that the channel was simplified to rectangular below the LiDAR water surface, while Manning’s channel friction estimates were between 0.03 and 0.035. The model predictions showed a close fit to the official rating curve and out-of-bank stage-discharge measurements, with the model-predicted uncertainty bounds able to contain 89.5% and 100% of the out-of-bank flow measurements for Montford and Norham respectively. This holds promising results for quantifying out-of-bank discharge uncertainties across large samples of catchments to enable robust national flood risk assessment.

How to cite: Coxon, G., Milsom, R., and Neal, J.: Estimating out-of-bank discharge uncertainties using a hydrodynamic model and nationally available datasets, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-3066, https://doi.org/10.5194/egusphere-egu2020-3066, 2020.

EGU2020-4300 | Displays | HS1.1.4

Application of Data Assimilation and Ensemble Kalman Filter for Flood Forecast in Tamsui River, Taiwan

Ming-hsi Hsu, Jin-Cheng Fu, Ming-Chun Tsao, and Nobuaki Kimura

Typhoon is the most frequent natural disaster that causes widespread damage during summer and autumn in Taiwan. On average, each year the island suffers four typhoons, which result in disastrous flash floods and losses in a short time because of steep terrains and intense rainfall. The Tamsui River Basin is located in northern Taiwan about 2,726 square kilometers and inhabited by eight million people. During flooding events, the emergency managers rely on accurate flood forecasting to take proper actions for damage reductions. The flood forecasting and warning system based on hydraulic models play an important role in flood risk management. This study first establishes river stage routing model based on dynamic wave theory. Then, both the real-time observed river stages and the least squares method are used to adjust the model currently flow conditions as the data assimilation. Finally, The Ensemble Kalman Filter method carries out the data correction with the computation of minimum error-covariance between the model prediction and the observation. The simulation results found the root-mean-square error of forecasted river stage using the data assimilation at the gauged stations of Taipei Bridge and Tudi-Gong-Bi for 1-3 hours lead time is 0.862m, 0.892m, 0.903m, and 0.281m, 0.326m, 0.345m, respectively. When the Ensemble Kalmen Filter is added in the model, the root-mean-square error reduces to 0.191m, 0.375m, 0.612m, and 0.062m, 0.090m, 0.145m at described gauged stations. It is found that the data assimilation and the Ensemble Kalmen Filter give reliable forecast water stages with a small root-mean-square error which successfully corrects the forecasted river stage at each time step of the flood routing process. The results reveal that the integrated model gains a better accuracy of the water-stage profiles with probabilistic uncertainties. The model provides reliable forecasts of the water-stage profiles for 1–3 hours lead time along the Tamsui River for specific locations in emergency response for flood risk management.

How to cite: Hsu, M., Fu, J.-C., Tsao, M.-C., and Kimura, N.: Application of Data Assimilation and Ensemble Kalman Filter for Flood Forecast in Tamsui River, Taiwan, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-4300, https://doi.org/10.5194/egusphere-egu2020-4300, 2020.

EGU2020-5296 | Displays | HS1.1.4 | Highlight

Bathymetric mapping in turbid braided mountain streams using SfM-MVS photogrammetry and statistical approaches

Davide Mancini, Gilles Antoniazza, and Stuart Lane

River bathymetric investigation has a long tradition as river-bed morphology is a crucial geomorphological variable that also has implications for river ecology and sediment management. In one sense, this is becoming more straightforward with the development of UAV platforms and SfM-MVS photogrammetry. Mapping inundated and exposed areas simultaneously has proved possible either by adopting two media refraction correction or by using some form of the Beer-Lambert Law. However, both of these approaches rely upon the bed being visible which becomes restricted to progressively shallower zones as stream turbidity increases. Traditional survey techniques to collect bathymetric data for inundated zones (e.g. total station or differential GPS systems) are time consuming and require a trade-off between point density and the spatial extent of survey. In this study we test a simple hypothesis: it is possible to generalize the likely depth of water in a shallow braided stream from basic planimetric information and use such statistical relationships to reconstruct the bathymetry of inundated zones. This is based upon the principle that a suite of planimetric variables (e.g. distance from stream banks, river channel width, local curvature magnitude and direction, streamline convergence and divergence) can be used to model the spatial distribution of water depths. We attempt to do this for a shallow braided river with high suspended sediment concentrations using orthoimages and DEMs derived from application of SfM-MVS photogrammetry to UAV-based imagery. We develop separate calibration and validation relationships to train and to assess the statistical models developed. These are then applied to the stream to produce bathymetric maps of flow depth for integration with SfM-MVS derived data from exposed areas. The method produces a point specific measure of uncertainty and tests suggest that the associated uncertainties are sufficiently low that after propagation into DEMs of difference reliable data on braided river dynamics and erosion and deposition volumes can be obtained.

How to cite: Mancini, D., Antoniazza, G., and Lane, S.: Bathymetric mapping in turbid braided mountain streams using SfM-MVS photogrammetry and statistical approaches, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-5296, https://doi.org/10.5194/egusphere-egu2020-5296, 2020.

EGU2020-6483 | Displays | HS1.1.4

A study on turbulence flow and pressure due to hydraulic jump

Seo Hye Choi, Hyung Suk Kim, and Moonhyung Park

The hydraulic jump occurs depending on conditions of upstream and downstream and makes large vortexes in itself of which flow is complex and fluctuates. Recently, the abnormal climate and gain of the impervious area increase the variation in river discharge. It can result in exerting the pressure that is over the acceptable load at the bottom in the downstream of a weir and increasing the fluctuation of the pressure due to the hydraulic jump. Those can provoke damages because of negative pressure, erosion of materials, local scour, and excess of the design load. Thus, this study aims at making use of the design in river-bed maintenance structures such as riprap and an apron considering by the pressure fluctuations. We simulated the hydraulic jump phenomenon through a hydraulic model experiment and examined the relationship between hydraulic factors and the pressure in the range of the hydraulic jump. Specifically, the hydraulic jump is generated by installing a weir upstream in the channel and measured the velocity of the flow by using particle image velocimetry (PIV) and bubble image velocimetry (BIV) to identify the characteristics of turbulence in the section of the hydraulic jump. Also, this study measured the pressure at the bottom along to the flow. As a result, the main factors of the pressure fluctuations are derived by statistical analysis such as determining the correlation between the pressure and the factors. In the subsequent study, it will be suggested to expect the pressure fluctuations at the bottom by using surrounding hydraulic factors in hydraulic jump through an elaborate analysis.

 

Acknowledgement

"This work is supported by the Korea Agency for Infrastructure Technology Advancement (KAIA) grant funded by the Ministry of Land, Infrastructure and Transport (Grant 20AWMP-C140010-03)."

How to cite: Choi, S. H., Kim, H. S., and Park, M.: A study on turbulence flow and pressure due to hydraulic jump, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-6483, https://doi.org/10.5194/egusphere-egu2020-6483, 2020.

EGU2020-8858 | Displays | HS1.1.4

ADCP with onboard GPS for streamflow velocity measurement usable for physical models calibration

Thomas Morlot, Pierre Oustriere, Franck Leclercq, and Hélène Scheepers

Human beings always wanted to protect themselves from hazards associated with rivers and streams. Wether we talk about low flow, pollution or flooding, streams very quickly interested scientists and engineers for their wealth and abilities.

EDF (Electricité de France) is a french company dealing with energy production. Dealer or owner operator of electricity production structures, the company is responsible for their operation in safe conditions. Thus, the knowledge of parameters such as streamflow discharge or streamflow velocities is one of its priorities to better respond to three key issues which are plant safety, compliance with reguatory requirements and optimization of the means of production.

The present work consists in showing how to use ADCP (Accoustic Doppler Current Profiler) to accurately measure streamflow volocities in complicated conditions (tide cycle, complex flow, bubbles, factory in operation…). Such device can be coupled with GPS to precisely geolocalize the measured velocities to make them usable for models calibration. By showing a case study, this work aims at underlining how field work using ADCP with onboard GPS can create input data for the adaptation and the calibration of physical models.

How to cite: Morlot, T., Oustriere, P., Leclercq, F., and Scheepers, H.: ADCP with onboard GPS for streamflow velocity measurement usable for physical models calibration, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-8858, https://doi.org/10.5194/egusphere-egu2020-8858, 2020.

EGU2020-13153 | Displays | HS1.1.4

Poking holes in discharge time series with photographic evidence

Anthony Michelon, Gilles Antoniazza, Natalie Ceperley, Stuart Lane, and Bettina Schaefli

River discharge is a key variable for hydrological studies and water resource management, but acquiring high-quality measurement remains challenging in mountain environments and in particular for mountain torrents. Extreme discharge variations between summer and winter, negative temperatures and intense sediment transport are the main issues for sensors (that get easily clogged, frozen or stucked out of the water) as well as for cross-section stability (a pre-condition for using a rating curve approach). 
In this presentation, we discuss what we learned from streamflow observations in the experimental Vallon de Nant catchment (13,4 km²), located in the Swiss Alps, which serves as a field laboratory for environmental research, ranging from plant ecology to snow hydrology and sediment transport to stream-C02 exchange with the atmosphere. We discuss here 4 years of optical height gauge records at the outlet (1200 m a.s.l.), obtained from a single VEGA-PULS WL-61 sensor measuring the water height above a concrete trapezoidal shaped cross-section (base width 5.3 m), designed primarily for sediment transport observations (with 10 geophones mounted flush on the concrete weir). There was no low flow channel within the cross-section. At least four other similar gauging stations are currently in use for hydrologic research in Switzerland, with or without low flow channels. The relevance of a discharge quality study at this site is twofold: i) to understand the reliability of flow measurements during low flow and during sediment-influenced high flow events and ii) to compile recommendations for similar discharge observation settings. 

At the Vallon de Nant study site, the absence of a low-flow channel in the weir, combined with the limitation of having a single river stage measuring point resulted in significant over- and under-estimation of the river stage at low-flows, caused by the fluctuation of the river bed position relative to that of the measuring point. Even if the flow covers the entire width of the weir crest, single clast deposits near to the crest can significantly disturb stage observations. We performed a validation of the data using hourly pictures taken during daytime with a low-cost camera at the outlet, and used the photographic evidence to identify periods when the river was partially or totally frozen, sediments were distorting the river stage measurements, and river channelization was occurring below or next to the river height sensor. Concurrent monitoring of temperature, conductivity or turbidity failed to identify these distortions. Consequently, significant error in discharge calculation would arise without a concurrent photographic observation. The key conclusion is that despite the growth of automation in measurements at gauging stations, there remains a need for observation of those stations, and if humans are no longer doing these, other digital technologies such as imaging need to be used instead. Our approach could be extended to night-time situations and locations that will go for extremely long periods without access.

How to cite: Michelon, A., Antoniazza, G., Ceperley, N., Lane, S., and Schaefli, B.: Poking holes in discharge time series with photographic evidence, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-13153, https://doi.org/10.5194/egusphere-egu2020-13153, 2020.

EGU2020-18930 | Displays | HS1.1.4

Evidence of long-term improvements in the quality and completeness of UK river flow data

Katie Muchan, Isabella Tindall, Harry Dixon, Stephen Turner, Catherine Sefton, and Jamie Hannaford

Globally, access to hydrometric data of adequate record length, quality and geographical coverage to answer research questions and manage freshwater systems remains a major issue. The UK National River Flow Archive (NRFA) provides stewardship of river flow data from over 1,500 locations across the UK. Data are acquired and displayed as ‘provisional’ in real-time for 500 stations, however the NRFA also undertake a full update to the quality controlled dataset on an annual basis. Upon submission, river flow records are subject to both automated data screening and manual methods of quality control by a team of trained hydrologists to ensure the data disseminated by the Archive to its broad user community are of the highest quality and fit-for-purpose for a range of applications. In the 1990s, an increasing number of gaps in river flow records and emerging declines in data quality resulted in the introduction of a Service Level Agreement (SLA) in 2002 to protect the UK’s hydrometric network and resulting data. Here, we present the results from 15 years application of the SLA system through the use of a set of quantifiable indicators of data quality, completeness and provision. The improvements shown demonstrate the benefits of such a system to the overall utility of the nationally archived river flow data and an example of quality control and performance indicator systems that can be used as a best practice model for other monitoring networks around the world. They also demonstrate one method of helping to ensure hydrological databases provide information of high quality to meet pressing research and water management needs today and into the future.

How to cite: Muchan, K., Tindall, I., Dixon, H., Turner, S., Sefton, C., and Hannaford, J.: Evidence of long-term improvements in the quality and completeness of UK river flow data , EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-18930, https://doi.org/10.5194/egusphere-egu2020-18930, 2020.

EGU2020-19427 | Displays | HS1.1.4

Quantifying the uncertainty in riverbank erosion for risk-informed river engineering

Eddy Langendoen and Mick Ursic

Riverbank erosion is a ubiquitous, natural process. Typically, it occurs during larger flood events when the applied forces exerted by the flowing water on a bank exceed some erosion-resistance threshold. Riverbank protection may be needed when critical infrastructure is present or planned near eroding banks, which requires the quantification of the risk of infrastructure failure by bank erosion. Similarly, renaturalization of many European streams, for example through removal of bank protection measures, necessitates the quantification of expected river width adjustment. Unfortunately, we have been unable to accurately quantify bank erosion rates to date. Limitations exist in characterizing both the applied and resisting forces. For example, bank roughness co-evolves with erosion, which makes it difficult to adequately resolve the forces acting on the bank material. Bank material erosion-resistance of fine-grained soils varies significantly, that is over orders of magnitude, both spatially and temporally. Moreover, existing techniques to measure bank material erosion-resistance do not always produce repeatable results. As a consequence, existing bank erosion models, such as the widely used Bank Stability and Toe Erosion Model (BSTEM), require extensive calibration and validation. This is often unsatisfactory to river engineering professionals that have to make decisions on where to place bank protection measures and the level of protection required. The decision-making process could benefit from a risk-based analysis that quantifies the uncertainty in calculated bank retreat rate. Recent enhancements to the BSTEM model allow users to input probability density functions of (measured) bank roughness and bank material erosion-resistance properties. A Monte Carlo analysis then quantifies the effects of both variability and uncertainty in these parameters on bank retreat. We will present how the shape of different probability density functions affect the probability density function of bank retreat. Results will be further presented of application of the new model to assist in prioritizing riverbank restoration measures along the Lower American and Sacramento Rivers, CA, USA, to prevent failure of levees that protect the City of Sacramento from flooding.

How to cite: Langendoen, E. and Ursic, M.: Quantifying the uncertainty in riverbank erosion for risk-informed river engineering, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-19427, https://doi.org/10.5194/egusphere-egu2020-19427, 2020.

In diverse developments such as hydropower potential assessment, flood mitigation studies, water supply, irrigation, bridge and culvert hydraulics, the magnitude of stream or river flows is a potential design input. Several methods of flow measurement exist; some basic and some more sophisticated. The sophisticated methods use equipment which, although they provide more accurate and reliable results, are invariably expensive and unaffordable by many institutions that depend greatly on flow records to plan and execute their projects. The need for skilled expertise in the use of these equipment and the associated maintenance problems preclude them from consideration in most projects developed and executed in developing regions such as Africa. For countries or institutions in these regions, there is a need for less expensive, but relatively reliable methods for stream or river flow measurement to be investigated; methods that require no equipment maintenance schemes. One such method is the float method in which the velocity of an object thrown in a river is measured by recording the time taken for the object to traverse a known distance and multiplying the velocity by the cross-sectional area of the river or stream. This method looks simplistic, but when flows obtained from it are correlated with those obtained from the more accurate and conventional methods, reliable results can be obtained. In this study, flow measurements were done at 42 different stream sections using the float method and a more reliable and generally accepted but expensive flow measurement method using a current meter. A statistical relationship was then developed between the flows obtained by the two methods by fitting a linear regression model to the set of data points obtained at the 42 locations on several reaches of selected streams in the western area of Freetown.  The study was conducted on streams with tranquil or laminar flow with flow magnitudes in the range of 0.39 m3/s to 4 m3/s in practically straight reaches with stable banks. The material of the stream beds was laterite soil. Thirty-two data sets were used to develop and calibrate the model and the remaining ten data sets were used to verify the model. The current meter method flows were regressed on the float method flows. For a significance level of 5%, the predicted flows of a current meter, given a float method flow, showed a high level of agreement with the observed current meter flows for the tested data set. 

How to cite: Kanu, I.: Stream Flow Measurement: Development of a Relationship between the Float Method and the Current Meter Method, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-21719, https://doi.org/10.5194/egusphere-egu2020-21719, 2020.

EGU2020-21212 | Displays | HS1.1.4

Estimation of paleo-discharge of the lost Saraswati River, north west India

Zafar Beg, Kumar Gaurav, and Sampat Kumar Tandon

The lost Saraswati has been described as a large perennial river which was 'lost' in the desert towards the end of the 'Indus-Saraswati civilisation'. It has been suggested that this paleo river flowed in the Sutlej-Yamuna interfluve, parallel to the present-day Indus River. Today, in this interfluve an ephemeral river- the Ghaggar flows along the abandoned course of the ‘lost’ Saraswati River. We examine the hypothesis given by Yashpal et al. (1980) that two Himalayan-fed rivers Sutlej and Yamuna were the tributaries of the lost Saraswati River, and constituted the bulk of its paleo-discharge. Subsequently, the recognition of the occurrence of thick fluvial sand bodies in the subsurface and the presence of a large number of Harappan sites in the interfluve region have been used to suggest that the Saraswati River was a large perennial river. Further, the wider course of about 4-7 km recognised from satellite imagery of Ghaggar-Hakra belt in between Suratgarh and Anupgarh in the Thar strengthens this hypothesis.

            In this study, we have developed a methodology to estimate the paleo-discharge and paleo-width of the lost Saraswati River. In doing so, we rely on the hypothesis which suggests that the ancient Saraswati River used to carry the combined flow or some part thereof of the Yamuna, Sutlej and Ghaggar River catchments. The paleo-discharge of the river would compare with that of some of the large river of the Himalayan Foreland. These alluvial rivers are often called self-formed rivers, as they flow on the loose sediment and are subjected to erosion and deposition of channel bed and banks. The geometry of rivers such as width (W), depth (D) and slope (S) are primarily controlled by water discharge (Q) and catchment area (A). Various functional relationships have been developed to scale the alluvial rivers, which we have used to obtain the first-order estimate of the river discharge of the ‘lost’ Saraswati. A scaling relationship was established between the catchment area-channel width for 31 rivers and catchment area-discharge at 26 different locations on the rivers presently flowing on the Himalayan Foreland from Indus in the west to the Brahmaputra in the East. We found the width and discharge of all the Himalayan rivers scale in a similar way when they are plotted against their corresponding catchment area. Using these regime curves, we calculate the width and discharge of paleochannels of the Sutlej, Yamuna and Ghaggar rivers by measuring their corresponding catchment area from satellite images. Finally, we add the discharge and width obtained from each of the contributions of individual catchments (Yamuna, Sutlej and Ghaggar River) to estimate the paleo width and paleo discharge respectively of the Saraswati River. Our regime curves provide a first-order estimate of the paleo-discharge and paleo-width of the lost Saraswati ~2500 cumec and ~1000 m respectively. We also suggest that the 4-7 km channel width observed earlier on the satellite image corresponds to the channel belt width of the lost Saraswati River.

How to cite: Beg, Z., Gaurav, K., and Kumar Tandon, S.: Estimation of paleo-discharge of the lost Saraswati River, north west India, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-21212, https://doi.org/10.5194/egusphere-egu2020-21212, 2020.

The development of new image-based techniques is allowing a radical change in the environmental monitoring field. The fundamental characteristics of these methods are related to the possibility of obtaining non-intrusive measurements even in adverse circumstances, such as high flow conditions, which may seriously threaten the operators’ safety conditions in traditional approaches.

Optical techniques, based on the acquisition, analysis and elaboration of sequences of images acquired by digital cameras, are aimed at a complete characterization of the river instantaneous surface velocity field, through the analysis of a floating tracer, which may be naturally present or artificially introduced. The growing availability of a new generation of both low-cost optical sensors and high-performing free software programs for image processing, is a key aspect explaining the rapid development of such techniques in recent years. The best known optical techniques are the large scale particle velocimetry (LSPIV) and the large scale particle tracking velocimetry (LSPTV).

This work is aimed to analyze and compare the performance of the two most common free software packages based on LSPIV (i.e. the PIVlab and the FUDAA-LSPIV), which use different cross-correlation algorithms. The test is carried out by analyzing several sequences of both synthetic images and real frames acquired on natural rivers under different environmental conditions (with tracers artificially introduced). An image sequences generator has been implemented ad-hoc with the aim to create, under fixed configurations, synthetic sequences of images, simulating uniformly distributed tracers moving under controlled conditions. The various configurations are characterized by different parameterization in terms of: (i) flow velocity (S=slow or F=fast flow conditions, according to a logarithmic transverse flow profile); (ii) tracer particles size (CON= disks of constant diameter; VAR=disks of variable size with given mean diameter); (iii) seeding density per frame (density: low -LD, medium -MD, high -HD).

The synthetic sequences are processed by the two software packages together with the real sequences, analyzing the errors in terms of mean value of the surface velocity field and velocity along a transverse transect, with respect to a benchmark velocity (i.e. that imposed in the image sequence generator for the synthetic sequences and that deriving from the use of traditional sensors, i.e. ADCP, for the real sequences).

How to cite: Pumo, D., Alongi, F., Ciraolo, G., and Noto, L.: On the use of LSPIV-based free software programs for the monitoring of river: testing the PIVlab and the FUDAA-LSPIV with synthetic and real image sequences, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-10155, https://doi.org/10.5194/egusphere-egu2020-10155, 2020.

EGU2020-22495 | Displays | HS1.1.4

Conceptualization of an anti-erosion sensing revetment for levee monitoring: experimental tests and numerical modelling

Manuel Bertulessi, Paolo Bianchini, Ilaria Boschini, Andrea Chiarini, Maddalena Ferrario, Nicola Mazzon, Giovanni Menduni, Jacopo Morosi, and Federica Zambrini

Smart levees represent a revolution in the field of embankment monitoring and safety during flood events. A smart levee, intended as the native (or “from scratch”) integration of an engineering structure with sensors and connection systems, provides detailed information on its past, current and future conditions Viz. integrity stress/strain conditions, maintenance state. This gives decision support to the figures in charge for maintenance and surveillance of the embankments, increasing efficiency and, particularly, the degree of protection from flood eventsSensor information can also be mashed up with other information, such as water stage, rainfall, soil wetness offering an useful integrated view of the river context. 

We present here first results of a research project concerning the conceptualization of a sensing anti-erosion revetment for embankments, through the integration of a double-twisted steel wire mesh with an optic fiber cable. The fiber is woven  into the double-twisted sections and is capable to detect the nearly continuous deformation of the meshes caused by stresses exerted in its plane. The sensor sensitivity is enough to record deformation due to (small) shear stresses exerted by eventual overtopping flows, though it can bear (and report) huge deformations typical of quite higher stresses up to thousands of microstrain. 

Several cycles of experiments, jointly with numerical modelling, clearly show the feasibility of such a product line, also showing a good linearity of the smart revetment behavior.

How to cite: Bertulessi, M., Bianchini, P., Boschini, I., Chiarini, A., Ferrario, M., Mazzon, N., Menduni, G., Morosi, J., and Zambrini, F.: Conceptualization of an anti-erosion sensing revetment for levee monitoring: experimental tests and numerical modelling, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-22495, https://doi.org/10.5194/egusphere-egu2020-22495, 2020.

HS1.2.1 – Pathways & society transdisciplinary approaches towards solving the Unsolved Problems in Hydrology (UPH)

EGU2020-364 | Displays | HS1.2.1 | Highlight

Solving the 23 Major Mysteries in Hydrology: Who Cares and Why?

Daniel Loucks

A recent paper (Bloeschl, et al. 2019) reported on the outcome of a multi-year effort involving over 200 scientists identifying the 23 most unsolved scientific issues facing the hydrologic community today.  The purpose of this exercise was to motivate the hydrologic research community to focus their work on these issues to better understand the major causes of how water behaves in our catchments, watersheds and river basins, often in different ways at various space and time scales, and under the influence of various degrees of human interactions. Aside from the scientific value that this increased understanding might bring, this presentation focuses on two questions: Why and how might this increased understanding be beneficial and who would benefit? In other words, who should care and why? This interactive presentation attempts to provide some answers to these two questions for each of the 23 identified unsolved scientific problems. But in general it is clear much of the impact that humans are having on our environment is driven by how the hydrologic cycle fits in with the needs of humans and our supporting ecosystems. Water in our environment affects the spread of contaminants and pathogens, the energy and food and industrial goods we produce, the ecosystem services we enjoy, and the duration and extent of floods and droughts some endure. Understanding these links and their economic, health, and social consequences will allow us to manage our water resources and their use more effectively, and perhaps even reduce the risks of reaching tipping points that could forever change how we all will live and survive in the future.    

How to cite: Loucks, D.: Solving the 23 Major Mysteries in Hydrology: Who Cares and Why? , EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-364, https://doi.org/10.5194/egusphere-egu2020-364, 2020.

EGU2020-11302 | Displays | HS1.2.1

The community consultation process leading to the compilation of the 23 Unsolved Problems in Hydrology (UPH)

Christophe Cudennec, Berit Arheimer, Günter Blöschl, Maria Helena Ramos, and Elena Toth

This contribution summarizes the steps of, and experiences with, a wide consultation process, led by the International Association of Hydrological Sciences (IAHS) that resulted in a list of 23 major unsolved scientific problems (UPH) in hydrology.

Step 1) Launch of a YouTube video, outlining the purpose of the initiative and its vision.

Step 2) Discussion via a LinkedIn group leading to a total of about 200 contributions and responses.

Steps 3-4) Two ‘in-person’ meetings organised in April 2019 in Vienna: one (Step 3) at the EGU General Assembly (attended by about 60 scientists), in order to solicit additional questions, at the end of which about 260 candidate problems had been compiled; the second one (Step 4) at the Vienna Catchment Science Symposium (VCSS) at the Vienna University of Technology (attended by about 110 scientists), to sort, merge, split, reword and prioritise the proposed questions. Through an iteration of parallel sessions (repeated twice, mixing the participants) and a final plenary voting session, a list of 16 ‘gold‘ and 29 ‘silver‘ questions was identified.

Step 5) Synthesis carried out by a small working group, involving representatives and members of IAHS, IAH, EGU and AGU, to consolidate, interpret and synthesise the questions, as well as to address potential biases in their selection that might have arisen from the composition of the participants at the meetings. The working group also pooled the questions into seven themes for clarity and communication. As a result of the synthesis process, the working group finally listed a set of 23 questions, presented in a community paper with over 200 authors (Blöschl et al., 2019, https://doi.org/10.1080/02626667.2019.1620507).

The UPH initiative is a proof of concept that this kind of broad consultation process is actually feasible, and is well received by the hydrological scientific community. Thus, equally important as the final list, is the community-level learning process of such a consultation, involving a large number of hydrologists and the four main learned societies in the field.

Consultations such as this could and should be repeated in the future for the benefit of our discipline, since providing common research subjects will increase the coherence of the scientific process in hydrology and promote the co-building of scientific strategies and synergy towards accelerated progress in hydrological sciences and applications.

This PICO presentation gives a short overview of the consultation process and of each of the 23 questions, shares the experiences from the process and proposes some possible future steps.

How to cite: Cudennec, C., Arheimer, B., Blöschl, G., Ramos, M. H., and Toth, E.: The community consultation process leading to the compilation of the 23 Unsolved Problems in Hydrology (UPH), EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-11302, https://doi.org/10.5194/egusphere-egu2020-11302, 2020.

This work could contribute to solve UPH #1: is the hydrological cycle regionally accelerating/decelerating under climate and environmental change, and are there tipping points (irreversible changes)?

This fundamental question hinges upon the Nature of the hydrologic cycle itself, and for which a geological perspective is needed.  To begin to solve this problem, we thus must have a clear picture of how the water cycle has changed throughout Earth’s History.  However, current narratives of the history of Earth's water cycle lack a coherent description of how life altered water cycling on land. Here I review a body of evidence of plant evolution events in Earth's history and propose how rainfall runoff mechanisms evolved through five key evolutionary phases.  This review reveals that for most of Earth's history, water cycling on land was likely very different from today, with fewer mechanisms available to store water between rainfall events in the critical surface zone, with implications for water availability and surface climate.  A key tipping point occurred during the Silurian-Devonian periods with the greening of the planet. This deep-time perspective illustrates the step-by-step process through which plants optimized the water cycle in which it increased the distribution in space and time, culminating in the development of forests in the late Devonian. Lastly, I review how the past may serve as a key to the future, discussing how the historical perspective illustrates key areas needed to improve our current conceptualization of water availability so that we may better understand and predict changes of water availability during the Anthropocene.

How to cite: Sterling, S.: A new deep-time historical perspective of the terrestrial water cycle that is needed to solve UPH #1: , EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-10606, https://doi.org/10.5194/egusphere-egu2020-10606, 2020.

EGU2020-19397 | Displays | HS1.2.1

Exploring the existence of hydrological tipping points at the catchment-scale

Fernando Jaramillo, Stefano Manzoni, Anne-Sophie Crepin, Juan Rocha, Lan Wang-Erlandson, Sam Zipper, Tom Gleeson, and Paolo D’Odorico

The identification of tipping points in the water cycle has been recently ranked Nr. 1 in the list of the top 23 unresolved problems in Hydrology by the International Association of Hydrological Sciences (IAHS) and as a priority in the field of hydrology and water resources by several studies. Such daunting task is mainly attributed to the concerns that greenhouse gas emission climate change may tip the water cycle into an unfavorable new state. Up to date, tipping points occurring in complex dynamical systems have been identified across a large set of disciplines. In most proven tipping points, hydrologic variables are always taken as the control variables, as changes in water fluxes and stocks are known to act as stressors of socioecological systems, and the affected aquatic and terrestrial ecosystems as the response variables. The main objective of this study is to explore the existence of tipping points in catchment-scale freshwater availability, that is, the tipping points were the response variable is catchment water storage. We first review the existence of reported tipping points in the field of hydrology and water resources, to establish a coherent framework for the identification of hydrological tipping points. We explore their mathematical existence at the catchment scale by Linear Stability Analysis, illustrating cases with potential functions and bifurcation diagrams. We then explore any possible contribution to the existence of hydrological tipping points by adding complexity to the hydrological dynamic system through the inclusion of sociological feedbacks. We find that even with the inclusion of the moisture feedback of evapotranspiration to precipitation, constant socioecological conditions will most likely not present tipping points of water storage in the catchment. However, the inclusion of socioecological feedbacks does generate tipping points under certain assumptions, even without assuming a moisture feedback between evapotranspiration and precipitation. We hope that this study sheds some light on the existence, conditions, assumptions and characteristics of large-scale hydrological tipping points with long-term implications.

How to cite: Jaramillo, F., Manzoni, S., Crepin, A.-S., Rocha, J., Wang-Erlandson, L., Zipper, S., Gleeson, T., and D’Odorico, P.: Exploring the existence of hydrological tipping points at the catchment-scale , EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-19397, https://doi.org/10.5194/egusphere-egu2020-19397, 2020.

Long period annual rainfall data series from nine raingauge stations throughout eastern India were analysed. Those data series were for the years 1901 to 1965 for Aijal (Mizoram); 1901 to 1984 for Imphal (Manipur); 1901 to 1986 for Guwahati (Assam), Shillong, Cherrapunji (Meghalaya); 1901 to 1987 for Cuttack (Odisha), Patna (Bihar), Agartala (Tripura), Krishnanagar (West Bengal). Incomplete annual rainfall data were found out by taking average of data of preceding and following years. Each annual rainfall series was divided into modelled period (1901 to 1980 for eight stations except Aijal with 1901 to 1960) and predicted period (data for years left in the series after modelled period for evaluation of the model for prediction of future rainfalls). Each annual rainfall series in the modelled period was first converted into percentage values of the mean annual rainfall and then plotted against year, which showed the oscillations of the historigram about the mean line (Tomlinson, 1987 for New Zealand rainfalls). Such type of characteristic historigrams for all stations showed periodic nature of annual rainfalls throughout eastern India. So, autoregressive integrated moving average (ARIMA) model (Clarke, 1973) was used to evolve a useful model for prediction of future rainfalls. As the ARIMA model was biased for periodicity due to inclusion of both the ‘sin’ and ‘cos’ functions and period length as 12, modelled data series were analysed for polynomial regression. The accepted degrees of polynomials were decided on the basis of analysis of variance (ANOVA). Acceptance of either ARIMA model or polynomial regression was done on the basis of -test. In most of the cases in the observed historigrams the lengths of periods were less than eight years and in some cases those were eight to 12 years and from polynomial regressions in most cases the period lengths varied in between 8 to 12 years, 13 to 22 years and 23 to 37 years; and in rare cases those lengths were 38 years and more. Considering all the limitations in the observed data and 95% confidence interval for ARIMA model, a particular amount of annual rainfall occurred at about 12 years (i.e. almost resembling a Solar Cycle) and that might be concluded after minute analysis of more observed data. Recurrence of flood and drought years can be predicted from such analysis and also by following probability analysis of excess and deficit runs of annual rainfalls (Panda et al., 1996).

References:

Clarke, R.T.1973. Mathematical models in hydrology. FAO Irrigation and Drainage Paper No. 19. FAO of the United Nations, Rome. pp.101-108.

Panda, S.; Datta, D.K. and Das, M.N. (1996). Prediction of drought and flood years in Eastern India using length of runs of annual rainfall. J. Soil Wat. Conserv. India. 40(3&4):184-191.

          https://www.academia.edu/15034719/Prediction_of_drought_and_flood_years_in_eastern_%20%09India%20using_length_of_runs_of_annual_rainfall

Tomlinson, A.I. (1987). Wet and dry years – seven years on. Soil & Water. Winter 1987: 8-9. ISSN 0038-0695    

How to cite: Panda, D. S.: Periodic occurrences of annual rainfalls in Eastern India [UPH No. 9 (theme: Variability of extremes) and UPH No.19 (theme: Modelling methods)], EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-4004, https://doi.org/10.5194/egusphere-egu2020-4004, 2020.

EGU2020-6126 | Displays | HS1.2.1

Can Continental Models Convey Useful Seasonal Hydrologic Information at the Catchment Scale?

Louise Crochemore, Maria-Helena Ramos, and Ilias Pechlivanidis

Climatic variations can have a significant impact on a number of water-related sectors. Managing such variations through accurate predictions is thus crucial. Continental hydro-climate services have recently received attention to address various user needs. However, predictions for months ahead can be limited at catchment scale, highlighting the need for data tailoring. Here, we address how seasonal forecasts from continental services can be used to address user needs at the catchment scale. We compare a continentally-calibrated process-based model (E-HYPE) and a catchment-specific parsimonious model (GR6J) to forecast streamflow in a set of French catchments.

This work provides insights into UPH 20 (How can we disentangle and reduce model structural/parameter/input uncertainty in hydrological prediction?) by proposing a skill assessment framework that isolates gains from hydrological model forcings and forecast initialisation. Our results show that a good estimation of the hydrologic states, such as soil moisture or lake levels, prior to the prediction is the most important factor in obtaining accurate streamflow predictions in both setups. We also show that the spread in internal model states varies largely between the two systems, reflecting the differences in their setups and calibration strategies, and highlighting that caution is needed before extracting hydrologic variables other than streamflow.

This work also provides insights into UPH 21 (How can the (un)certainty in hydrological predictions be communicated to decision makers and the general public?). Despite the expected high performance from the catchment setup against observed streamflow, the continental setup can, in some catchments, match the catchment-specific setup for 3-month aggregations and when looking at statistics relative to model climatology, such as anomalies. Nevertheless, differences in the setups can result in different uncertainties for variables such as soil water content.

How to cite: Crochemore, L., Ramos, M.-H., and Pechlivanidis, I.: Can Continental Models Convey Useful Seasonal Hydrologic Information at the Catchment Scale?, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-6126, https://doi.org/10.5194/egusphere-egu2020-6126, 2020.

EGU2020-6111 | Displays | HS1.2.1

Machine Learning is Central to the Future of Hydrological Modeling

Grey Nearing, Frederik Kratzert, Craig Pelissier, Daniel Klotz, Jonathan Frame, and Hoshin Gupta

This talk addresses aspects of three of the seven UPH themes: (i) time variability and change, (ii) space variability and scaling, and (iii) modeling methods. 

During the community contribution phase of the 23 Unsolved Problems effort, one of the suggested questions was “Does Machine Learning have a real role in hydrological modeling?” The final UPH paper claimed that “Most hydrologists would probably agree that [extrapolating to changing conditions] will require a more process-based rather than calibration-based approach as calibrated conceptual models do not usually extrapolate well.” In this talk we will present a collection of recent experiments that demonstrate how catchment models based on deep learning can account for both temporal nonstationarity and spatial information transfer (e.g., from gauged to ungauged catchments), often achieving significantly superior predictive performance compared to other state-of-the-art (process-based) modeling strategies, while also providing interpretable results. This is due to the fact that deep learning can learn, exploit, and explain catchment and hydrologic similarity in ways and with accuracies that the community has not been able to achieve using traditional methods. 

We argue that the results we have obtained motivate a path forward for hydrological modeling that centers around ‘physics-informed machine learning.’ Future model development might focus on building hybrid (AI + process-informed) models with three objectives: (i) integrating known catchment behaviors into models that are also able to learn directly from data, (ii)  building explainable deep learning models that allow us to extract scientific insights, and (iii) building hybrid models that are also able to simulate unobserved or sparsely observed variables. We argue further that while the sentiments expressed in the UPH paper about process-based modeling are common, the community currently lacks an evidence-based understanding of where and when process-based understanding is important for future predictions, and that addressing this question in a meaningful way will require true hybrids between different modeling approaches.

We will conclude by providing two fundamentally novel examples of physics-informed machine learning applied to catchment-scale and point-scale modeling: (i) conservation-constrained neural network architectures applied to rainfall-runoff processes, and (ii) integrating machine learning into existing process-based models to learn unmodeled hydrologic behaviors. We will show results from applying these strategies to the CAMELS dataset in a rainfall-runoff context, and also to FluxNet soil moisture data sets.

How to cite: Nearing, G., Kratzert, F., Pelissier, C., Klotz, D., Frame, J., and Gupta, H.: Machine Learning is Central to the Future of Hydrological Modeling, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-6111, https://doi.org/10.5194/egusphere-egu2020-6111, 2020.

EGU2020-10001 | Displays | HS1.2.1

Panta Rhei Benchmark Dataset

Heidi Kreibich, Giuliano di Baldassarre, Anne van Loon, Kai Schröter, Philip Ward, Fuqiang Tian, Alberto Viglione, Murugesu Sivapalan, and Günter Blöschl

We tackle the unsolved problem in hydrology “How can we extract information from available data on human and water systems in order to inform the building process of socio-hydrological models and conceptualisations?”

In the framework of the Panta Rhei initiative we compile and analyse a benchmark dataset, which shall be used to calibrate and apply socio-hydrological models. The compilation and analyses of the benchmark dataset will be undertaken as follows: 1) selection of suitable socio-hydrological models; 2) identification of the variables necessary to calibrate and apply the selected models; 3) collection of time series data of the selected variables for as many catchments as possible; 4) calibration and application of the socio-hydrological models; 5) comparative analyses across different models and catchments.

A minimum of two, preferably more socio-hydrological models for floods and droughts shall be selected. Data collection will be undertaken with the support of the Panta Rhei community, particularly the members of the Panta Rhei working groups “Changes in flood risk” and “Droughts in the Anthropocene”. For the socio-hydrological model calibration we plan to follow the example of Barendrecht et al. (2019). This PICO presentation shall be used to discuss and finalise the concept for data compilation and analyses, to promote this initiative and to motivate as many colleague as possible to contribute to the data collection and comparative analyses.

Reference: Barendrecht, M. H., Viglione, A., Kreibich, H., Merz, B., Vorogushyn, S., Blöschl, G. (2019): The value of empirical data for estimating the parameters of a socio-hydrological flood risk model. WRR, 55, 2, 1312-1336. DOI: http://doi.org/10.1029/2018WR024128

How to cite: Kreibich, H., di Baldassarre, G., van Loon, A., Schröter, K., Ward, P., Tian, F., Viglione, A., Sivapalan, M., and Blöschl, G.: Panta Rhei Benchmark Dataset, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-10001, https://doi.org/10.5194/egusphere-egu2020-10001, 2020.

EGU2020-7431 | Displays | HS1.2.1

Unsolved problems in hydrology: societal responses to unprecedented events

Maria Rusca, Giuliano Di Baldassarre, and Gabriele Messori

Understanding how different societal groups respond to drought or flood events is one of the unsolved problems in hydrology (UPH), concerning the interfaces with society. More specifically, there is a need to decipher the relationship between potential impacts of unprecedented events, distribution of sociohydrological risk as well as future adaptation and recovery trajectories. In this presentation, we introduce a new analytical approach to answer the question of how contemporary societies might adapt to and recover from unprecedented drought and flood events in an inclusive and sustainable fashion. In doing so, this presentation deepens our understandings of the interface between hydrological extremes and society. Addressing this question requires creating new forms of knowledge that integrate analyses of the past, i.e. historical and political processes of risk and adaptation and the underlying power relations, with hydroclimatic projections of unprecedented events. We thus combine three aspects which have been studied individually, but never integrated: a. scenarios based on social science theories on disaster management; b. case studies of past hydroclimatic events which were unprecedented at the time of their occurrence; c. conceptual transfer across case studies - that is, learning something about potential future unprecedented events at one location by leveraging events which occurred elsewhere. Some of the scenarios developed may already be emerging in current times, whilst others are plausible hypotheses in humanity’s future space. This approach, at the nexus between social and hydrological sciences, has the concrete advantage of providing an impacts-focussed vision of future risk, beyond what is achievable within conventional disciplinary boundaries. 

How to cite: Rusca, M., Di Baldassarre, G., and Messori, G.: Unsolved problems in hydrology: societal responses to unprecedented events, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-7431, https://doi.org/10.5194/egusphere-egu2020-7431, 2020.

EGU2020-5221 | Displays | HS1.2.1

Social science for hydrologists: considerations when doing fieldwork with human participants

Sally Rangecroft, Eddie Banks, Rosie Day, Guiliano Di Baldassarre, Theresa Frommen, Yasunori Hayashi, Britta Höllermann, Karen Lebek, Elena Mondino, Melanie Rohse, Maria Rusca, Marthe Wens, and Anne Van Loon

Water is at the core of many current and future global challenges, which involve hydrological, technical and social processes. Therefore, successful interdisciplinary research on how water-related issues interact with human activities, actions and responses is increasingly important. Qualitative data and diverse perspectives provide much-needed information to improve our understanding and management of water-related issues. To collect this information, hydrologists are increasingly conducting fieldwork with human participants (e.g. individuals, policy-makers, community leaders, government representatives, etc.) themselves, and collaboratively with others. Although collaboration between hydrologists and social scientists in interdisciplinary projects is becoming more common, several barriers, including lack of understanding and experience, can result in hydrologists and social scientists remaining somewhat separate during research, leading to suboptimal research outcomes. Hydrologists who are planning and undertaking fieldwork involving human participants may be underprepared because they are unfamiliar with key social science approaches and concepts. Therefore, here, we help guide hydrologists to better understand some important issues to consider when working with human participants, to facilitate more collaborative research.

As a group of social, natural, and interdisciplinary scientists, we discuss a number of important elements of fieldwork involving human participants that hydrologists might be unfamiliar with, or might have different approaches to than social scientists. These elements include good ethical practice, research question frameworks, power dynamics, communication of science (e.g. participatory mapping, photovoice, videography, and interactive graphs), and post-fieldwork reflections. There are also issues to consider when working collaboratively with social scientists, such as vocabulary differences and different methodologies and data collection approaches (e.g. interviews, focus groups, questionnaires, workshops, ethnography).

We believe that by introducing hydrologists (and natural scientists in general) to some of the key considerations when working with human participants in the field, more holistic, ethical, and successful research outcomes can be achieved. We also want to stress that collaboration with social scientists stays important and research ethics, design, participant involvement, and results, may be compromised without the input and experience of social scientists themselves. Facilitating these collaborations between the natural and social sciences will improve interdisciplinary water research, resulting in a better understanding of the interactions between water and society.

How to cite: Rangecroft, S., Banks, E., Day, R., Di Baldassarre, G., Frommen, T., Hayashi, Y., Höllermann, B., Lebek, K., Mondino, E., Rohse, M., Rusca, M., Wens, M., and Van Loon, A.: Social science for hydrologists: considerations when doing fieldwork with human participants, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-5221, https://doi.org/10.5194/egusphere-egu2020-5221, 2020.

EGU2020-1485 * | Displays | HS1.2.1 | Highlight

Learning from the past for strategic decision-making in climate risk management: Connecting historic and future adaptation pathways

Thomas Thaler, Philipp Babcicky, Christoph Clar, Thomas Schinko, and Sebastian Seebauer

Hydro-metrological events cause substantial economic damage and social disruption in our society to date. These climate-related risks will become even more severe in the future, driven by changes in the frequency and magnitude of natural hazard events, an increasing exposure of buildings or infrastructure, as well as vulnerability and resilience developments of residents and businesses. Although these long-term developments are of major social and economic relevance, decisions in disaster risk management and their (potential) impacts are typically assessed as singular events and potential alternative solutions, which have not been considered, are out of scope. Recent research therefore suggests to employ the concept of iterative climate risk management (CRM), in order to align disaster risk management and climate change adaptation policy and practice. This is supposed to increase the awareness of how complex and dynamic the challenge of comprehensively tackling climate-related risks is.

Pathways aims to fill this gap by analysing the long-term development of past and future decisions. The arenas in which these decisions are made are characterised by (1) competing interests from various policy areas, (2) ad-hoc decisions often taking precedence over strategic planning for long-term CRM, and (3) previous decisions providing carry-over, follow-up or creating even lock-in effects for later decisions. Focusing on two climate-adaptation regions in Austria (so-called KLAR!-regions), Pathways paints a comprehensive picture of how local adaptation pathways were developed in the past, how these pathways led to specific decisions at specific points in time, and which impacts these choices had on community development with respect to the choices and pathways not taken. Pathways learns from the past to inform the future with the aim to provide capacity building at the local level. By understanding how earlier decisions enabled or constrained the later decisions, pathways offers policy guidance for making robust decisions in local CRM.

Pathways applies a mixed-method approach to integrate quantitative and qualitative social science research methods and to triangulate the research objectives from different perspectives. Semi-structured interviews with key CRM actors at various levels of government, geo-spatial analysis, secondary analysis of census data and archival research jointly inform the reconstruction of past decision points and related pathways. This approach allows to test, compare, confirm, and control the collected data and the interpreted results from different perspectives, while avoiding narrow, oversimplifying explanations. Building on the lessons learnt from the past, future pathways are co-designed with local stakeholders in Formative Scenario workshops. Pathways restricts its scope to climate-related risks from extreme hydro-meteorological events and geological mass movements, such as riverine floods and pluvial torrents, mud and debris flow, landslides or avalanches. This risk domain requires governance structures for immediate response to the disaster as well as for prevention and relief/reconstruction. Pathways aims to improve the knowledge base for respective governance efforts.

How to cite: Thaler, T., Babcicky, P., Clar, C., Schinko, T., and Seebauer, S.: Learning from the past for strategic decision-making in climate risk management: Connecting historic and future adaptation pathways , EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-1485, https://doi.org/10.5194/egusphere-egu2020-1485, 2020.

The U.S. Geological Survey, through the National Water Census, has produced a near real-time, operational concept map of water availability for the conterminous United States. Currently, this map aggregates “natural” landscape-dimension storage volumes (e.g. soil moisture, snowpack, and surface depression storage) and relates these values to historic averages for a given spatial unit for the given time of year. The purpose of this operational concept map is to improve communication of current water availability to the general public using the best available knowledge and technology. Current operational model deployment is an application of nationally-consistent methods; however, the degree to which regionalization and local knowledge might be applied and interwoven into the national product are current topics of exploration. In addition, future development for this model and visualization process will include adding water quality and water use as variables that contribute to the overall availability of water. Adding these transdisciplinary components to the existing physical model is not straightforward; the differences in model structure and data types needed for specific disciplines will need to be overcome to present a truly integrated water availability estimate that can provide useful information for the public as well as the technical research community. In this presentation, we explore the successes and challenges of the existing operational model used for the National Water Census, including transdisciplinary model integration, calibration, and uncertainty, with the goal of improving communication of water availability.

How to cite: Driscoll, J. M. and Farmer, W. H.: Integrated, operational water availability estimates for the conterminous United States: transdisciplinary data and modeling successes and challenges, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-10811, https://doi.org/10.5194/egusphere-egu2020-10811, 2020.

EGU2020-11432 | Displays | HS1.2.1

Co-creation processes of nature based solutions in hydrological modelling – case studies in the UK, Belgium and the Netherlands

Borjana Bogatinoska, Angelique Lansu, Judith Floor, Dave Huitema, and Stefan Dekker

Climate adaptation of brook catchments is much needed in the studied regions of England, Belgium and the Netherlands. With the continuous rise of global temperatures and global change, these regions suffer from the impacts of extreme weather events such as drought and flooding. Extreme weather and climate change impacts are spatially non-uniform, uncertain and can have different strengths at local and regional level. Therefore, cities and regions need to adapt to climate change in an ambiguous way. Accordingly, there is no uniformity in the adaptive capacity of individuals, groups within society, organisations and governments or how they can respond to current and future climate change impacts.

To better understand the interlinkages in nature-based climate adaptation between the socio-economic and climate change drivers, we studied these drivers in the hydrological modelling in 3 pilot studies in the UK, the Netherlands and Belgium. Focus is on how co-creation, defined as active participation is incorporated in the hydrological modelling process, (1) within each brook catchment and (2) between the professionals, as cross border knowledge transfer. Data on the co-creation process was collected with workshops on each of the semi-annual partner meetings of each catchment. Data on the modelling process was collected by semi-structured interviews of the professionals and by using assessment of professional learning in the network (field trips). Findings on co-creation processes of nature based solutions in hydrological modelling will be compared in the UK, the Netherlands and Belgium. In the end, existing co-creation processes will be joined to a framework for co-creation which can be improved and adapted based on the gathered data. This would include: identification of stakeholder groups and their needs, the level of intended participation, the identified climate problem by the stakeholders and by the policy-makers, the planned modelling approach, the NbS etc.

Keywords: climate change, hydrology, nature-based solutions, stakeholders, climate adaptation, framework.

How to cite: Bogatinoska, B., Lansu, A., Floor, J., Huitema, D., and Dekker, S.: Co-creation processes of nature based solutions in hydrological modelling – case studies in the UK, Belgium and the Netherlands, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-11432, https://doi.org/10.5194/egusphere-egu2020-11432, 2020.

New and unconventional sources of data that enhance our understanding of internal interactions between socio-economic and hydrological processes is central to sociohydrological modelling. Participatory modelling (PM) departs from conventional modelling tools by informing and conceptualizing sociohydrological models through stakeholder engagement. However, the implementation of most PM processes remains biased, particularly in regions where marginalized communities are present. Most PM processes are not cognizant of differentiation and diversity within a society and tend to treat communities as homogeneous units with similar capabilities, needs, and interests. This undifferentiation leads to the exclusion of key actors, many of whom are associated with marginalized communities. In this study, a participatory model-building framework (PMBF), aiming to ensure the inclusiveness of marginalized stakeholders - who (1) have low literacy, (2) are comparatively powerless, and/or (3) are associated with a minoritized language - in participatory sociohydrological modelling is proposed. The adopted approach employs interdisciplinary storylines to inform and conceptualize system dynamics-based sociohydrological models.The suggested method is underpinned by the Multi-level Perspective (MLP) framework, which was developed by Geels et al. (2002) to conceptualize socio-technical transitions and modified in this study to accommodate the development of interdisciplinary storylines. A case study was conducted in Atitlán Basin, Guatemala, to understand the relationships that govern the lake’s cultural eutrophication problem. This research integrated key stakeholders from the indigenous Mayan community, associated with diverse literacy ranges, and emerging from three different minoritized linguistic backgrounds (Kaqchikel, Tz’utujil, and K’iche’), in the PM activity. The generated model serves as a decision support system for managing nutrient discharge into Lake Atitlán, allowing stakeholders to investigate trends of different policy and management scenarios. The participatory model-building activity helped eliminate the impact of power imbalances in water resources management and empower community-based decision-making.

How to cite: Bou Nassar, J., Malard, J., Adamowski, J., Ramírez Ramírez, M., and Tuy, H.: The use of interdisciplinary storylines to ensure the inclusiveness of marginalized stakeholders in participatory sociohydrological modelling: A case study in Tz’olöj Ya’, Mayan Guatemala, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-11178, https://doi.org/10.5194/egusphere-egu2020-11178, 2020.

EGU2020-20035 | Displays | HS1.2.1

Cooperation under conflict: a framework for participatory modeling under severe social and climate change pressures

Anahi Ocampo-Melgar, Pilar Barria, and Cristian Chadwick

Hydrological modeling tools are usually used to obtain broad scale understandings of ecological and hydrological interconnections in a basin. They have also been presented as useful to support collaborative decision processes by visually displaying hydrological systems connections, uncertainties and gaps, as well conflicting preferences over water management strategies. However, many challenges remain at capturing and communicating the complexity of couple human-hydrological systems. The Aculeo basin in Chile is an internationally publicized case due to the disappearance of a 12 km2 lake that leaded to increasing conflicts over water scarcity and the cause of the catastrophe. A traditional hydrological model study and a separate collaborative agreement process were implemented in parallel to find answers and discuss solutions to the water scarcity crisis. The model initially designed to answer a single water balance question, was finally turned in a question-driven socio-hydrological modeling process used to explore a diversity of uncertainties emanating from the collaborative agreement process. Model development and some results of this integration are presented, displaying how science-policy process forces adjusting model structure, challenging official information and searching for alternatives sources and approaches to find answers. This research presents how a hydrological model can be used as a dynamic framework to address poor knowledge on the system behavior, disagreements on the water crisis causes and contradictions on the management options proposed. However, it also shows that participation can be an instance used by stakeholders to question and challenge the rigidity, scope and accuracy of the model information being presented. Therefore, flexible approaches and research agendas should support the exploration of this type of synergies towards more collaboration and production of useful and legitimate socio-hydrological models. 

How to cite: Ocampo-Melgar, A., Barria, P., and Chadwick, C.: Cooperation under conflict: a framework for participatory modeling under severe social and climate change pressures, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-20035, https://doi.org/10.5194/egusphere-egu2020-20035, 2020.

HS1.2.3 – The Science-policy interface in hydrology – essentials for more impactful science

This presentation discusses the issue of bridging science, policy, industry and practitioners communities as well as the citizen dimension for enhancing disaster resilience. It focuses on the development and consolidation of the Community of Users (CoU) on Secure, Safe and Resilient Societies, an exchange platform of the European Commission. The CoU is an initiative from DG Home and aims to create a platform to exchange information on research results and policy updates between policy-makers, researchers and end-users on a European, national and regional level. Its motivation lies on the fact that there is a large span of policies and research projects users, leading to fragmentation of information and lost opportunities regarding possible synergies. There is a strong need to boost awareness about research projects and policy developments. Besides, user’s needs are often insufficiently targeted and should be considered in the light of research programming. Links among scientific outputs and policy objectives are often lacking and there is a need to strengthen cooperation and dialogue among the different communities. This presentation will highlight current research programming and perspectives in Horizon Europe and policy implementation.

How to cite: Quevauviller, P.: Bridging science, policy, industry and practitioners communities and the citizen dimension for enhancing disaster resilience, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-22290, https://doi.org/10.5194/egusphere-egu2020-22290, 2020.

EGU2020-14173 | Displays | HS1.2.3 | Highlight

Flood emergencies and hydrological science communication

Hannah Cloke

Flood emergencies are a cauldron of politics, media, operational agencies working hard on the ground and of course people’s lives, livelihoods, property and wellbeing put at risk by floodwaters.  Government and humanitarian agencies need to rapidly understand the gravity of a situation and their options to respond. To help them make decisions, and to ensure these decisions are based on evidence and not speculation, they often draft in advisory groups made of up experts in relevant fields. For floods this could include engineers, flood and weather forecasters, agricultural economists or land owners. For a hydrologist, being asked to advise governments in an emergency situation is scary and exciting, but also a wonderful opportunity to put your scientific expertise to use helping people. The key skill in these situations is understanding how and when to speak up. You must speak clearly, use simple language that non-scientists can understand, and you often only have a few seconds to convey your points. You may be faced with opposition, yet you must rely on your training and expertise to make rapid judgements and to point to the best evidence available.  Using real-life examples from flooding crises in the UK, Africa and elsewhere, we will see how it is possible to use scientific skill to directly help people by influencing decisions. By working with governments, emergency agencies and NGOs, scientists can help them to make best use of resources and even save lives.

How to cite: Cloke, H.: Flood emergencies and hydrological science communication, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-14173, https://doi.org/10.5194/egusphere-egu2020-14173, 2020.

EGU2020-14093 | Displays | HS1.2.3

science-policy interface: the italian experience

corina angela

Over the last 15 years, in the framework of the Italian early warning system, managed directly by the civil protection authorities, the gap between science and policy have been positively bridged with the Knowledge Centres: a national strategy, with a formal architecture that has build a dialogue between scientific community and responsibility services.
The applied research, tailored on operational user needs, has been funded and supported leading to the development of advanced applications in coupled meteo-hydrological modelling, satellite rapid damage analysis, hydraulic modelling, levees vulnerability estimation etc.
Similar interface models are being created in the European institutions (DRMKC, European Commission) or in the international expert Agencies ( Research Panel, WMO).
The general positive dialogue among science and policy, in a mutual enrichment, is presented in this paper. 

How to cite: angela, C.: science-policy interface: the italian experience, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-14093, https://doi.org/10.5194/egusphere-egu2020-14093, 2020.

EGU2020-13929 | Displays | HS1.2.3

Existential crises of riverine eco-systems: an echoing environmental epidemic in Europe and India

Sasi Varadharajan and Gabriela Adina Morosanu

Sand mining is a pressing environmental, ecological and economic problem that has now transcended national borders and regional boundaries. This ongoing challenge for rivers has been in the spotlight of policy makers but, it is yet to be locked under an adequate legislation. The presentation discusses the need for targeted legislation to ensure compliance with the spatial and volumetric limits imposed for sand mining activities, so that the conservation of water and sediment resources and the preservation of the hydro-morphological conditions of the watercourses and geo-morphology of adjacent farm lands and bank bunds can be achieved. In this regard, the analysis of existing regulations across countries is a necessity to arrive at a desirable combat cum conservation framework against the degrading dredging.

The analysis is attempted at an inter-continental level - between the European Union and India; regardless of their dimensionality within the Eurasian space and the extent of potential environmental threats on the entire population, the comparison of Indian and EU legal systems can be justified from various viewpoints. Firstly, it helps in studying the intended and implemented effects of environmental legislations within a Union of internal States (India) and a Union of Countries (EU); the underlying impact-wise distinctions between an innately centralized Domestic system and an International system with space for individuality and Sovereignty of independent States; Secondly, it helps in tracing the legislative progress and environmental reach of domestic statutes and regional agreements that stem from Constitutional mandate and International public morality respectively; Thirdly, it helps in mapping the reasons why a system with numerous sand mining legislations (like the TNMMC rules dating back to 1950s in India) and elaborate Environment Impact Assessment (EIA) guidelines has produced little impact on practical handles than the regional system with fewer soft laws (like the EU Water Framework Directive 60/EC/2000) and faint national innovations.

Since the common goal of both systems is the protection, restoration and enhancement of the health of ecologies, this comprehensive study will complement their efforts; it will stress on the science-policy interface in creating a more impactful legal regime by showcasing country-wise case studies; weighing the advantages and disadvantages of a regional system with greater space for international co-operation and a national system more dependent on internal regulation will benefit the policy makers in improvising and fail-proofing the existing standards and green practices; the consequential hydro-sedimentary and geo-morphological impacts of sand mining can only be avoided by finding the right balance through the study of different systems.

Keywords: Sand Mining, Environmental Impact Assessment, Ecology, Geomorphology, Legislative Practices, the European Union, India.

How to cite: Varadharajan, S. and Morosanu, G. A.: Existential crises of riverine eco-systems: an echoing environmental epidemic in Europe and India, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-13929, https://doi.org/10.5194/egusphere-egu2020-13929, 2020.

Over the past 20 years, river water quality in Indonesia has deteriorated enormously. Water quality deterioration continues to increase socio-economic inequality, as it are the most poor communities who live on and along the river. Women are comparatively highly impacted by failing water resources management, but their involvement in decision making processes is limited. As such, the uneven water quality related disease burden in Brantas River Basin widens the socio-economic gap between societal groups. In the Brantas region, cooperation and intention between stakeholders to tackle these issues is growing, but is fragile as well due to overlapping institutional mandates, poor status of water quality monitoring networks, and limited commitment of industries to treat their waste water streams. Currently, an Indonesian-Dutch consortium develops a project which is built on the premise that water problems of our world do not necessarily have to be only a cause of tension, but can also be a catalyst for cooperation. Cooperation is a process that needs active input from all concerned. As such, this project seeks to support a twinned learning process in which science is used to build a trusted information system for policy and decision making in Brantas river basin management. The project focuses on the close links between research processes of data gathering and monitoring and its relevance for societal and institutional actors within river basin management organizations. This twinning between policies and science aims to facilitate learning processes of basin authorities, societal stakeholders, companies and knowledge institutions, as they can profit from each other’s achievements, knowledge and experiences. One of the important issues for this new cooperative partnership is how to develop procedures and routines to monitor water quality in the Brantas river. Participatory data monitoring is among the prime requirements for sustainable river management. An additional dimension of the already challenging issue of data gathering in river management is how to deal with transdisciplinary issues in monitoring, measurements and measures, including research procedures and institutional setup.

How to cite: Ertsen, M.: Water quality policies in the Brantas River Basin, Indonesia, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-9700, https://doi.org/10.5194/egusphere-egu2020-9700, 2020.

EGU2020-11015 | Displays | HS1.2.3

Using Dynamic Adaptive Policy Pathways and hydrological modelling to co-create water resource adaptation policies for climate change: a practical example for southern Portugal

João Pedro Nunes, Luís Filipe Dias, Bruno A. Aparício, Inês Morais, Ana Lúcia Fonseca, Amandine Valérie Pastor, and Filipe Duarte Santos

Mediterranean agricultural systems often rely on irrigation, which can cause conflicts with domestic water demand due to limited water resources. Climate change could enhance these conflicts by bringing a drier climate, lowering water availability, while increasing irrigation demands, therefore creating a need for timely adaptation actions. However, the creation of adaptation plans requires the integration of local policy-makers and stakeholders, both to ensure that the plans are adjusted to local physical and social conditions, and to secure investment in the implementation phase. As many are not technical experts in water resources, this integration requires innovative methodologies to ensure that knowledge gained from advanced hydrological methods can be effectively transmitted for use.

These issues were addressed in the climate change adaptation plan for water resources in the Algarve region (southern Portugal), which was co-created between hydrologists and local stakeholders and policy-makers under project CLIMAAA, by using the Dynamic Adaptive Policy Pathways (DAAP) approach to synthetize the results from hydrological modelling of future scenarios.

Future scenarios were simulated from the present until 2100 using a hydrological model, with multiple realizations of climate scenarios RCP4.5and RCP8.5. The results show an increase in water stress conditions, mainly in the RCP8.5 scenario. Future scenarios and potential adaptation measures were discussed with the local policy-makers (regional and municipal water managers) and water users (water utilities, farmer associations). An agreed-upon set of measures was then simulated with the model to assess their effectiveness for adaptation. These results were used to design a DAAP specifically for the water sector in the Algarve.

Policy-makers were then presented with the DAPP, combined with a cost assessment, and selected the most suitable and politically reliable adaptation pathway until 2100. They did not consider socially desirable to decrease irrigation use, and showed a strong preference for measures such as promoting efficient water use and water retention landscapes, which are distributed and incremental, to measures such as wastewater recycling which require a large investment. However, they did consider desalination as a last resort despite the high investment, to be applied in case other measures fail to maintain water stress below an acceptable threshold. In the end, an adaptation plan for water resources was co-created between policy-makers and researchers which strongly reflected local desires and preferences, while ensuring that its effectiveness was assessed with the best available tools; this plan is now in in the review and implementation stage.

How to cite: Nunes, J. P., Dias, L. F., Aparício, B. A., Morais, I., Fonseca, A. L., Pastor, A. V., and Santos, F. D.: Using Dynamic Adaptive Policy Pathways and hydrological modelling to co-create water resource adaptation policies for climate change: a practical example for southern Portugal, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-11015, https://doi.org/10.5194/egusphere-egu2020-11015, 2020.

Increasing water scarcity and water-related disasters are key challenges of climate change that every continent is facing today. Southeast Asia and Africa where many developing countries are concentrated in are highly vulnerable to the impact of climate change. Especially, countries sharing river basins and located in coastal regions have been experiencing high levels of water stress mainly due to population growth and climate change. According to a recent UN report, it is estimated that more than five billion people could suffer from water shortages by 2050 because of increased water demand and climate change. In most cases, however, these people who live in least developed countries (LDCs), which have high population densities and high dependence on primary industry such as agriculture, forestry and fishing required for continuous water supply and efficient water management systems, have been already suffering from extreme levels of water stress but have less capacity and fewer resources to adapt or cope with this extreme condition. Therefore, in this study, impacts of climate change on the global water resources and water-related disasters were reviewed and analyzed in the context of the UN Climate Change Conference COP25, which was held in Spain from 2 to 13 December 2019 and discussed the most important and sensitive issues with regards to climate change adaptation and greenhouse gas mitigation among invited delegates and participants representing 197 countries.

 

Acknowledgements

This research was carried out as a part of “Development of the Global Water Atlas for responding to climate change project (grant number 20190404-001)” funded by the Ministry of Science and ICT, South Korea.

How to cite: Kim, Y.: Review and analysis of the global water issues in the context of COP25, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-1693, https://doi.org/10.5194/egusphere-egu2020-1693, 2020.

EGU2020-21623 * | Displays | HS1.2.3 | Highlight

The science-policy interface – in need for "society" as a third component

Jutta Thielen-del Pozo, Lise Autogena, Joshua Portway, and Florian Pappenberger

The European Union is funding research through so-called framework programmes (FPs), the financial and strategic tools to stimulate excellence, innovation, economic growth and creation of jobs across Europe. The allocated research budgets increased considerably from less than 4 billion Euro for FP1 (4 years) to 100 billion for Horizon Europe (FP9, 7 years), demonstrating the strategic importance that is being attributed to research and development for a strong and competitive Europe. The upcoming framework programme Horizon Europe will add a new level of ambition for the scientific, economic as well as societal impact of EU funding and address global challenges that affect the quality of our daily lives.

However, if societal issues that affect our everyday lives are to be addressed effectively in research and to drive the necessary innovation process in view of a better future, then the third component at the science-policy interface must be “society”. Robust data, facts and evidences represent an important input to policy making in addition to other inputs and considerations. Scientists and policy makers must therefore not only network amongst their communities and experts but also interact with the public and engage in dialogue with citizens in order to first understand what the concerns and issues are and later to explain the solutions.

The Joint Research Centre has engaged in an Art, Science and Society programme to fill this gap. Artists are invited to the JRC to co-develop projects with the scientists under a specific theme – in 2015 the topic was “Food”, in 2017 “Fairness” and in 2019 “Big Data, Digital Transformation and Artificial Intelligence”. The final works are exhibited during the so-called Resonances Festival.

This presentation illustrates at the example of the Resonances III installation “Weather Prediction by Numerical Process - a forecast for Europe” by artists Lise Autogena and Joshua Portway in collaboration with the co-authors, the added value of this approach. The installation is a performance inspired by the work of L.F. Richardson (1881–1953), a truly multi-disciplinary scientist, who contributed to finite difference solutions of partial differential equations, turbulent flow and diffusion, also fractals, and the cause and evolution of conflicts. He was particularly visionary in his work on designing a numerical scheme for weather forecasting. While serving as ambulance driver during WWI, he performed the calculation for a weather forecast for Europe “by hand”. Even if the result of his years of calculations resulted in a wrong forecast because the numerical solution was not stable, the methodology for numerical weather forecast was born and today’s weather forecasts follow largely the same method – just with infinite more computing power. Richardson estimated that 64000 scientists, working together in a big orchestrated calculation, would be needed to calculate the weather in real-time.

The chosen format for the art installation is a performance, ritualistically re-enacting a small part of this epic calculation, drawing the audience into a multi-faceted discussion on the relevance of Richardson’s legacy today in the times of super computing and climate change.

How to cite: Thielen-del Pozo, J., Autogena, L., Portway, J., and Pappenberger, F.: The science-policy interface – in need for "society" as a third component, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-21623, https://doi.org/10.5194/egusphere-egu2020-21623, 2020.

EGU2020-13594 | Displays | HS1.2.3

What methods of interaction with users have proved to better perform for advanced co-development of climate services in the water sector?

María José Polo, Rafael Pimentel, María José Pérez-Palazón, Pedro Torralbo, Little Lorna, Marilyn Menezes-Lomba, Christiana Photiadou, and Berit Arheimer

A wide offer of climate data sources/services is currently available dealing with future climate scenarios and projections. A huge effort has been done at European scale to promote and share openly this information. However, their use is not extensive and their potential is frequently underexploited. There is usually a significant gap between the complexity of climate metadata and the users’ capability of exploiting them. Furthermore, this gap is also found between the expertise of climate data providers and the every-day operation of the different potentially interested end-users. Additionally, in some sectors users are not aware of climate service capabilities which prevent them from valuing and then demanding such services.

In this context, co-development improves and fosters climate services’ usability and uptake when compared to a traditional one-side development approach, since it best meets users’ needs and demands. However, co-development can be time-consuming for both sides and less effective than expected if an adequate communication design is missing. In this context, what methods of interaction with users have proved to better perform for advanced co-development of climate services? And, what factors have best motivated users to interact? are key questions to provide guidelines and profit from the on-going initiatives.

Three different approaches with users (mainly in the water sector) were tested: guided online surveys (anonymous users); focus groups (users known to different partners in the project); case study clients (users regularly interact with project partners). Indicators and metrics were used to evaluate and value the contribution from each group in the context of co-development of climate services that give future projections of water availability. The results of this comparison provide a conceptual framework to design and apply co-development strategies for climate services oriented to different groups within the water sector.

This work was funded by the project AQUACLEW, which is part of ERA4CS, an ERA-NET initiated by JPI Climate, and funded by FORMAS (SE), DLR (DE), BMWFW (AT), IFD (DK), MINECO (ES), ANR (FR) with co-funding by the European Commission [Grant 690462].

How to cite: Polo, M. J., Pimentel, R., Pérez-Palazón, M. J., Torralbo, P., Lorna, L., Menezes-Lomba, M., Photiadou, C., and Arheimer, B.: What methods of interaction with users have proved to better perform for advanced co-development of climate services in the water sector?, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-13594, https://doi.org/10.5194/egusphere-egu2020-13594, 2020.

EGU2020-17960 | Displays | HS1.2.3

Participatory water resources monitoring as a science-policy tool: a decade of experience from the Andes

Boris Ochoa-Tocachi, Wouter Buytaert, and Bert De Bièvre

Evidence-based decision making is seen as the key to sustainable water resource and catchment management. However, a major obstacle for evidence generation is the limited amount of data available from in-situ hydrometeorological monitoring. Monitoring is in decline globally, and this problem is particularly acute in high-elevation environments and in the tropics. Nevertheless, this situation also puts these environments in a promising position to study the potential of multi-source, polycentric generated information to tackle data scarcity.

Established in 2009, a bottom-up partnership of academic and non-governmental institutions pioneered participatory hydrological monitoring in the tropical Andes. Participatory approaches to environmental monitoring are becoming increasingly popular and are being promoted as a potential pathway to address long-standing data gaps. The partnership, known as the Regional Initiative for Hydrological Monitoring of Andean Ecosystems (iMHEA from its Spanish abbreviation) has instrumented a network of more than 30 headwater research catchments (< 20 km2) covering four major biomes (páramo, jalca, puna, and forest) in nine locations of the tropical Andes. Precipitation and streamflow are monitored at high frequency with the involvement of local communities, governments, and research institutions. The network is designed to characterize the impacts of changes in land use and watershed interventions on catchment hydrological response and has started delivering fundamental information to guide processes of decision making more effectively and influencing policy-making on water resources at local and national scales.

Participatory water resources monitoring can be seen a science-policy tool. Here we present the drivers and context of the process that led to the creation of iMHEA, currently one of the largest initiatives of grassroots and participatory environmental monitoring in the world, and the main challenges that lie ahead. Observational data from experimental catchments have an essential value for hydrology and water resources management that increases with time. The long-term sustainability in the monitoring will allow a deeper understanding of current uncertainties, including seasonality, natural variability, environmental changes, and extreme events such as drought and flooding.

How to cite: Ochoa-Tocachi, B., Buytaert, W., and De Bièvre, B.: Participatory water resources monitoring as a science-policy tool: a decade of experience from the Andes, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-17960, https://doi.org/10.5194/egusphere-egu2020-17960, 2020.

EGU2020-20350 | Displays | HS1.2.3

Bridging the science-policy gap in a transition-country setting: enablers and barriers

Micha Werner, Nora van Cauwenbergh, Tibor Stigter, Leonardo Alfonso Segura, Teresita Betancur Vargas, Alberto Galvis, and Humberto Avila

Despite a significant increase in attention for uptake of scientific results, the integration of emerging science in policy development and implementation remains challenging. The persistent gap between science and policy may frustrate the parties involved. For the scientists, the intended impacts of what are typically very much applied research efforts remain unattained. Those involved in policy implementation and development may perceive a lack of scientific support. This may particularly be the case in transitional countries, where the development of science may struggle to keep up with rapid societal and policy development; with several factors either impeding or facilitating the uptake of emergent scientific knowledge.

We implemented a series of participatory and action research activities to support the development and implementation of groundwater management policies in Colombia and explore barriers and enabling conditions to a functional science-policy interface. The factors that either impede or facilitate the process are examined through three case studies in different regions of the country. Although the national policies that govern groundwater resources management in these three areas are the same; the degree to which scientific knowledge is used to support policy implementation varies. Several factors are identified that influence the effectivity of the linkage, including among others; the availability of scientific knowledge; the establishing of trust relationships and positioning of institutions and stakeholders; as well as institutional readiness in supporting the policy implementation process. This comparison provides useful insight into how addressing some of the impeding factors may enrich the science-policy process.

How to cite: Werner, M., van Cauwenbergh, N., Stigter, T., Alfonso Segura, L., Betancur Vargas, T., Galvis, A., and Avila, H.: Bridging the science-policy gap in a transition-country setting: enablers and barriers, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-20350, https://doi.org/10.5194/egusphere-egu2020-20350, 2020.

Almost ten years ago, we published a paper where we raised the question whether effective communication of uncertainty in hydro-meteorological forecasts was an impossible mission (Ramos et al. Meteorol. Appl. 17: 223–235, 2010, DOI: 10.1002/met.202). We wanted to understand if the multiple ways of interpreting uncertainty, as well as the multiple users and forecasting situations affecting forecast display and confidence, could hamper probabilistic forecast communication in operational hydrological forecasting. We looked at the main general interconnections present in a typical flood forecasting and alert chain, the challenges of extracting meaningful information from probabilistic forecasts and the way ensemble forecasts were effectively used in flood warning and decision-making. At the end, we were optimistic to say that the “mission is not impossible, although the tasks to be executed might be difficult to accomplish.” Here, we discuss a follow-up question: what have we accomplished in terms of communicating uncertainty in hydrological forecasts in practice, and contributing to better inform decision-making? The impact of forecasts, in terms of, for instance, anticipation of extreme events and crisis management, depends on how good they are but also on how they are understood and used in practice. This requires connecting science, operations and decision-making through the forecasting chain. We present some experiments with role-play games and benchmarking skilful streamflow forecasts developed to better understand the way probabilistic predictions can support decisions, and discuss where successes were achieved and challenges remain.

How to cite: Ramos, M.-H. and Pappenberger, F.: Connecting science, operations and decision-making when communicating uncertainty in hydro-meteorological forecasting, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-20257, https://doi.org/10.5194/egusphere-egu2020-20257, 2020.

Complex water optimisation problems represent one of the biggest challenges of the near future due to human and climate impacts. On the one hand, stakeholders in the water supply sector require high-level knowledge of the whole water cycle process at different scales, with the aim to either assess the risk for uncertain future water availability or rely on more analytic approaches for decision making. On the other hand, scientific research produces high quality models, algorithms and schemes capable of solving the water problems, but scientists often struggle when it comes to deploy tools that deliver their research outcomes to stakeholders and decision makers that ultimately will use them. The principal goal of this project is to fill the gap between the development of innovative research methodologies and their practical usability in the real world. We present “RApp”, a web-based application written purely in R within the Shiny framework and developed in collaboration with the water supply company Romagna Acque SpA. RApp simulates and visualizes the behavior of the reservoir that sustains the drinking water supply system of the Romagna region, Italy, in order to support its optimal management. Reservoir simulations are obtained connecting, through a unique and site-specific modelling chain, the inflows from the upstream catchments, the functioning of the reservoir, the potential of the treatment plant and the water demand. The optimized monthly-based management rules were obtained off-line, through a multi-objective optimization algorithm by maximizing the water yields and, at the same time, minimizing the occurrence of water outages during drought periods. The RApp user can produce quick reports of the past and expected reservoir yields and stored volumes, in terms of either graphical or table outputs, as a function of different initial and boundary conditions provided by the users, such as the initial stored volume, the expected inflows, the adoption of optimized or user-defined management rules, the occurrence of an abrupt change in the water demand, thus, allowing stakeholders to explore the impact of different scenarios and management options. For developing the tool, a very close interaction between the research group and the stakeholders was required, and is still ongoing, in order to define and then expand the functionalities of the software that are most needed for its practical use.

How to cite: Pugliese, A., Neri, M., Brath, A., and Toth, E.: Converting scientific research into a practical tool co-designed with the stakeholders in R Shiny: a web-based application for managing the main reservoir of the drinking water supply system in the Romagna region, Italy, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-19508, https://doi.org/10.5194/egusphere-egu2020-19508, 2020.

EGU2020-11254 | Displays | HS1.2.3

eWaterCycle: Fully open en transparant hydrological data and modelling platform facilitates FAIR policy making.

Rolf Hut, Caitlyn Hall, Niels Drost, and Nick van de Giesen

In Spring 2019, eScience Center Netherlands and Delft University of Technology facilitated a workshop to develop a FAIR – Findable, Accessible, Interoperable, Reusable – multi-application platform that hydrological experts and non-experts can use to guide their decision-making. Many hydrologists believe that there are too many models in the field. Each new research generation strives to improve current methods with increasing complexity and developing individual models to fit specific situations - and to what end? If other experts struggle to adapt a model, it’s unreasonable to expect a non-expert to gain meaningful insight to address challenges impacting a community or guide policy.

 A community-driven platform (eWatercycle) has been developed by an international multi-disciplinary team of hydrologists, research software engineers, tinkerers, science policy advisors, and more. The diverse and inclusive team membership is critical to ensure that the best possible tool is developed to address multi-faceted questions and benefit a wide-reaching community. eWatercycle incorporates many popular hydrological models (e.g., SUMMA, PCRGLOB-WB, WFLOW, and HYPE). We have incorporated the massive ERA5 climate reanalysis dataset, as well as global stream gauge data, such that users can analyze a system for any region. 

Considering the potential complexity from eWatercycle’s inclusion of several model types, the team continues to develope this model framework in close cooperation with potential end-users. We envision end-users may include a government scientist working to inform policy decisions on water management or city officials developing risk management strategies for extreme weather events. Users of eWatercycle will not be required to learn new programming languages or overcome significant technical barriers to begin using the framework. As a result, users will be able to use eWatercycle to work towards solving region-specific problems with confidence by considering the outcomes of different hydrological models and access to potential uncertainty in the available data and modeling techniques.

We will demonstrate the latest version of the eWatercycle platform, it's models, data and analyses capabilities. 

How to cite: Hut, R., Hall, C., Drost, N., and van de Giesen, N.: eWaterCycle: Fully open en transparant hydrological data and modelling platform facilitates FAIR policy making., EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-11254, https://doi.org/10.5194/egusphere-egu2020-11254, 2020.

EGU2020-882 | Displays | HS1.2.3

Hidden Stories in Hydrologic Literature: An Interactive Topic-Based Ontology

Mashrekur Rahman, Grey Nearing, and Jonathan Frame

Hydrologic research generates massive volumes of peer-reviewed literature across a plethora of evolving topics and sub-topics. It’s becoming increasingly difficult for scientists and practitioners to synthesize and leverage the full body of scientific literature. Recent advancement of computational linguistics, machine learning, including a variety of toolboxes for Natural Language Processing (NLP), help facilitate analysis of vast electronic corpuses for a multitude of objectives. Research papers published as electronic text files in different journals offer windows into trending topics and developments, and NLP allows us to extract information and insight about these trends. 

 

This project applies Latent Dirichlet Allocation (LDA) Topic Modeling for bibliometric analyses of all peer-reviewed articles in selected high-impact (Impact Factor > 0.9) journals in hydrology (Water Resources Research, Hydrology and Earth System Sciences, Journal of Hydrology,  Hydrological Processes, Advances in Water Resources, Hydrological Sciences Journal, Journal of Hydrometeorology). Topic modeling uses statistical algorithms to extract semantic information from a collection of texts and has become an emerging quantitative method to assess substantial textual data. After acquiring all the papers published in the aforementioned journals and applying multiple pre-processing routines including removing punctuations, nonsensical texts, stopwords, and tokenizing, stemming, lemmatization etc., the resultant corpus was fed to the LDA model for ‘learning’ latent intellectual topics. We achieved this using Gensim, an open-source Python library widely used for unsupervised semantic modeling with LDA. The optimal number of topics (k) and model hyperparameters were decided using coherence and perplexity values for multiple LDA models with varying k.  The resulting generated topics are interpretable based on our prior knowledge of hydrology and related sub-disciplines. Comparative topic trend, term, and document level cluster analyses based on different time periods, journals and authors were performed. These analyses revealed topics such as climate change research gaining popularity in Hydrology over the last decade. 

 

We aim to use these results combined with probability distribution between topics, journals and authors to create an interactive ontology map that is useful for research scientists and environmental consultants for exploring relevant literature based on topics and topic relationships. The primary objective of this work is to allow science practitioners to explore new branches and connections in the Hydrology literature, and to facilitate comprehensive and inclusive literature reviews. Second-order beneficiaries are decision and policy makers: the proposed project will provide insights into current research trends and help identify transitions and argumentative viewpoints in hydrologic research. The outcomes of this project will also serve as tools to facilitate effective science communication and aid in bridging gaps between scientists and stakeholders of their research.



How to cite: Rahman, M., Nearing, G., and Frame, J.: Hidden Stories in Hydrologic Literature: An Interactive Topic-Based Ontology, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-882, https://doi.org/10.5194/egusphere-egu2020-882, 2020.

HS1.2.4 – Panta Rhei: Hydrology, Society & Environmental Change

EGU2020-5551 | Displays | HS1.2.4 | Highlight

Limits to natural disasters management: the influence of human behavior

Jeroen Aerts

Despite billions of dollars of investments in disaster risk reduction (DRR), data over the period 1994- 2013 show natural disasters caused 1.35 million lives. Science respond with more timely and accurate information on the dynamics of risk and vulnerability of natural hazards, such as floods. This information is essential for designing and implementing effective climate change adaptation and DRR policies. However, how much do we really know about how the main agents in DRR (individuals, businesses, government, NGO) use this data? How do agents behave before, during, and after a disaster, since this can dramatically affect the impact and recovery time. Since existing risk assessment methods rarely include this critical ‘behavioral adaptation’ factor, significant progress has been made in the scientific community to address human adaptation activities (development of flood protection, reservoir operations, land management practices) in physically based risk models.

This presentation gives an historic overview of the most important developments in DRR science for flood risk. Traditional risk methods integrate vulnerability and adaptation using a ‘top- down’ scenario approach, where climate change, socio economic trends and adaptation are treated as external forcing to a physically based risk model (e.g. hydrological or storm surge model). Vulnerability research has made significant steps in identifying the relevant vulnerability indicators, but has not yet provided the necessary tools to dynamically integrate vulnerability in flood risk models.

However, recent research show novel methods to integrate human adaptive behavior with flood risk models. By integrating behavioral adaptation dynamics in Agent Based Risk Models, may lead to a more realistic characterization of the risks and improved assessment of the effectiveness of risk management strategies and investments. With these improved methods, it is also shown that in the coming decades, human behavior is an important driver to flood risk projections as compared to other drivers, such as climate change. This presentation shows how these recent innovations for flood risk assessment provides novel insight for flood risk management policies.

How to cite: Aerts, J.: Limits to natural disasters management: the influence of human behavior, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-5551, https://doi.org/10.5194/egusphere-egu2020-5551, 2020.

EGU2020-2659 | Displays | HS1.2.4

Capturing flood risk dynamics with a coupled agent-based and hydraulic modelling framework

Tamara Michaelis, Luigia Brandimarte, Giuliano Di Baldassarre, and Maurizio Mazzoleni

Floods are one of the costliest natural hazards worldwide, affecting millions of people every year. To plan flood risk reduction strategies, there is a need to understand how risk changes over time. In traditional flood risk assessment, vulnerability is often unrealistically considered constant in time, which does not reflect patterns observed in the real world. The coupled human and natural flood system is complex and determined by two-way interactions between the two subsystems. Floodplain dynamics may affect human behavior (e.g. by triggering the implementation of protection measures at different scales) which changes exposure and vulnerability, while they are also in turn influenced by human activities (e.g. land-use changes or flood protection structures). Here we explore how these two-way interactions influence changes in flood risk over time, with a focus on the role of individual and governmental decision-making, by developing a coupled agent-based and hydraulic modelling framework.

In our framework, household agents are located in a floodplain protected by a levee system. Individual behavior is based on Protection Motivation Theory and it comprises (as a response to floods) the options to do nothing, invest in private flood protection measures, or file a complaint to the government. The governmental decision making process about the implementation of technical flood protection measures, i.e. reinforcing the levee system, is a compromise between a Cost-Benefit-Analysis and relative number of filed complaints from the households. The agents take decisions at every time step of a long time series of annual maximum water levels: in case of levee breach, the floodplain water level is estimated by the LISFLOOD 2D hydraulic model, which is dynamically coupled into the agent-based model.

We show that this coupled model is capable of replicating adaptation and levee effects, which have been empirically observed by several scholars in numerous floodplains around the world. Thus, our framework provides a useful explanatory tool for assessing different spatial and temporal dynamics of flood risk in a socio-hydrological system. Moreover, the new modelling approach can explicitly simulate the spatial distribution of flood risk which allows for the analysis of conflicting interests in neighbouring communities. First, efforts have been made to include farmer agents into the model to simulate conflicts between urban and rural areas. Further, we exploit data from the real word in order to assess the credibility of our model and, lastly, use the model to investigate the effects of different climate scenarios on these types of conflicts.

 

How to cite: Michaelis, T., Brandimarte, L., Di Baldassarre, G., and Mazzoleni, M.: Capturing flood risk dynamics with a coupled agent-based and hydraulic modelling framework, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-2659, https://doi.org/10.5194/egusphere-egu2020-2659, 2020.

EGU2020-16099 | Displays | HS1.2.4

A comparative analysis of property level flood mitigation behaviour in the regions of England

Marlies H Barendrecht, Simon McCarthy, and Alberto Viglione

Even though there has been a move towards a more integrated approach to flood risk management, with a stronger focus on property level measures to reduce flood risk, the uptake of property level measures remains low. Experience has been found to influence the uptake of measures, but even property owners with experience do not always take measures to prepare for future flooding. In this paper we investigate the variations in the relationship between experience and preparedness (i.e. the uptake of property level measures) for the different regions of England. We use survey data collected among the population at risk in the years 1996 to 2004 and perform a hierarchical beta regression to determine the differences between the seven regions. We find that the South West and Southern regions have a higher increase in preparedness with increasing experience compared to other regions. In the Thames, Midlands and North West the preparedness increases less with increasing experience. Based on an analysis of additional data sources (e.g. surveys and maps of structural protection and population) we provide a possible explanation as to why the behaviour of property owners in these regions could be different.

How to cite: Barendrecht, M. H., McCarthy, S., and Viglione, A.: A comparative analysis of property level flood mitigation behaviour in the regions of England, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-16099, https://doi.org/10.5194/egusphere-egu2020-16099, 2020.

EGU2020-659 | Displays | HS1.2.4

Exploring the role of risk perception in influencing flood losses over time

Elena Ridolfi, Frederike Albrecht, and Giuliano Di Baldassarre

What implications do societies’ risk perceptions have for flood losses? This study uses a stylized, socio-hydrological model to simulate the mutual feedbacks between human societies and flood events. It integrates hydrological modelling with cultural theory and proposes four ideal types of society that reflect existing dominant risk perception and management: risk neglecting, risk monitoring, risk downplaying and risk controlling societies. We explore the consequent trajectories of flood risk generated by the interactions between floods and people for these ideal types of society over time. Results suggest that flood losses are substantially reduced when awareness raising attitudes are promoted through inclusive, participatory approaches in the community. In contrast, societies that rely on top-down hierarchies and structural measures to protect settlements on floodplains may still suffer significant losses during extreme events. This study illustrates how predictions formed through social science theories can be applied and tested in hydrological modelling.

How to cite: Ridolfi, E., Albrecht, F., and Di Baldassarre, G.: Exploring the role of risk perception in influencing flood losses over time, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-659, https://doi.org/10.5194/egusphere-egu2020-659, 2020.

EGU2020-5764 | Displays | HS1.2.4

Community awareness of climate change and urban flood risk: the case of the Simeto River Basin

Paola Nanni, Rosaria Ester Musumeci, David J. Peres, and Antonino Cancelliere

Increased urbanization is causing evident negative consequences on the hydrological cycle. In particular, the increase of impervious surfaces is having a strong impact on the water cycle, amplifying the risk of urban floods. These impacts can get even worse for potential climate change impacts. The urban areas of the Simeto Valley, the largest river valley in Sicily (Italy), has been repeatedly hit by heavy rains in the last decades that caused urban flooding causing several problems and, in some instances, threats to population. The threats seem to derive also from a low awareness of the population on the correct behavior to have in potentially dangerous situations. Hence, it seems of key importance that residents develop and internalize a “culture of risk awareness”. The Life SimetoRES Project represents an opportunity to stimulate the development of a responsible and resilient community and at the implementation of best practices for storm water management. In the Simeto River Valley community has started in the recent decades to formally have an identity (for instance, by signing a River Agreement) and has already supported initiatives in the responsible and participatory co-management of the territory. Thus, this Valley represents an excellent context to investigate this problem and to understand the involvement of the citizens in solving climate change and urban floods. In order to maximize the effectiveness of the communication campaigns and the actions to safeguard the community, a study through a survey on the climate change and risk perception in 11 municipalities has been carried out, collecting 1143 answers. Starting from the current hydrogeological risk, quantified by the Flood Risk Management Plan, the goal was to identify the perception and the awareness of the citizens. A section of the questionnaire involved the direct experience of the residents during rain events, their relationship with the alert system and their knowledge of the correct behavior in case of flood. Finally, the survey investigated the willingness of citizens to implement adaptation actions in their own municipality and in their homes. The results show that over 52% of citizens is not aware of the real use of the infrastructures devised for urban drainage and only the 30% feels responsible about mitigation of flooding risk. Inaccurate weather warnings can endanger more inhabitants who don't trust the alert system. The results show that it is necessary to make incisive actions to educate people, especially in school age, on the correct behavior to take in case of urban flooding, and encourage citizens to acknowledge themselves as an active part of the mechanism of their own and community safety.

How to cite: Nanni, P., Musumeci, R. E., Peres, D. J., and Cancelliere, A.: Community awareness of climate change and urban flood risk: the case of the Simeto River Basin, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-5764, https://doi.org/10.5194/egusphere-egu2020-5764, 2020.

EGU2020-21382 | Displays | HS1.2.4

Explaining the pitfalls of quantifying population in riverine floodplains using Nighttime Light

Lisa Verschuren, Fernando Nardi, Jeremy Bricker, Olivier Hoes, Serena Ceola, and Saket Pande

Flooding is globally one of the most damaging natural hazards. Flood risk will most likely increase in the near future due to increases in flood frequency attributed to climate change and growth in population and wealth in flood prone areas. This growth in wealth and population is increasingly considered as a major driver for the increase in flood losses in the last decades. Floodplains are susceptible to floods, but historically people have always been settling in floodplains. The growth of population in floodplains, which is a substantial cause for increased flood risk, is essential to consider for decision making in floodplain development, as improper development increases flood exposure and aggravates flood risk. The science of socio-hydrology tries to capture the interaction between humans and floods in the floodplain, but it is necessary to identify these mechanisms on a broader scale. A way of doing this, is to look at the development of floodplain population density over the years, but population data is not available on a long temporal scale. Therefore, Nighttime light data was used to model the gaps in the availability of population data. Nighttime light data captures the illumination on earth and is available on a large temporal and spatial scale. It also has a high correlation with population data. However, the relationship between Nighttime light data and population data is not straightforward. This study tries to model a population proxy using Nighttime light data and explains when and why it does or does not work. Validation of the model shows that in some regions the predicted data is relatively precise, but ultimately, due to the lack of data, the accuracy is unknown. This study shows that understanding the behavior of NTL is valuable, because it has the potential to map Socio-Economic variables in data-scarce areas.

How to cite: Verschuren, L., Nardi, F., Bricker, J., Hoes, O., Ceola, S., and Pande, S.: Explaining the pitfalls of quantifying population in riverine floodplains using Nighttime Light, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-21382, https://doi.org/10.5194/egusphere-egu2020-21382, 2020.

EGU2020-254 | Displays | HS1.2.4

Anthropogenic and climatic controls on surface water loss across USA

Irene Palazzoli and Serena Ceola

Surface water resources are severely affected by human activities and climate variability, and their rapid depletion is one of the main challenges for sustainable development. This situation is expected to worsen because of climate change, world population growth and the associated conversion of rural lands into urban areas. Since about 70% of global population is projected to be living in cities by 2050, it is necessary to shed light on the influence of climate and human dynamics on water occurrence variation to better understand their driving role.

Remote sensing is a key tool for monitoring the process of environmental change because it provides the advantages of global spatial coverage, high temporal resolution, and fast updating. Satellite data enable to record changes in climatic conditions, land use, and spatial allocation of human settlement and activities, which are major factors in altering water dynamics. However, the potential of such data has not been fully exploited.

Here, the interrelation between spatial and temporal distribution of water depletion, changes in precipitation, and human dynamics across the USA watersheds is investigated using remote sensing data. In particular, the contribution of urbanization and precipitation variation to surface water decrease in the last 35 years (from 1984 to 2018) is evaluated at the basin scale. Preliminary results highlight the presence of a positive correlation between surface water loss and urban area growth. On the other hand, a counterintuitive increasing trend of surface water decrease with growing annual precipitation is found. A multiple linear regression among surface water loss, urbanization, and annual precipitation change is calculated, showing that most of the surface water loss can be attributed to the urbanization process. A spatial and temporal clustering analysis is then performed to better understand the influence of anthropogenic factors on surface water losses. Results clearly show a high level of urbanization close to surface water loss hotspots.

How to cite: Palazzoli, I. and Ceola, S.: Anthropogenic and climatic controls on surface water loss across USA, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-254, https://doi.org/10.5194/egusphere-egu2020-254, 2020.

As one of the major weather-driven natural disasters, droughts exhibit as the most frequent and widespread natural disasters in China. It is reported that the agriculture losses show continuously grown by following the increasingly severe droughts for the whole country. In order to investigate the impacts of drought on agricultural, we rechecked the functional relationship between the crop yield and climatic variables. Based on the meta-analysis from previous literature, we found a more stable statistical relationship between the yield and the precipitation and evapotranspiration. These results introduce a new drought index, indicated as Crop Water-Related Index for Drought (CWRID), which can be used as a reference index to approximate the drought impact on the loss of yield. Based on the climatic data in China during 1982-2015, several other drought indices (SPI, SPEI, CI, and SEDI) were compared with CWRID to identify the most appropriate agricultural drought index. The data of historical drought damaged area and drought damaged crop yield reduction were used to validate the performances of different indices. The CWRID reasonably predicted the drought damaged area as well as the drought damaged yield reduction during the past 30 years in China. As a contrast, the SEDI is proved to be no suit for quantifying drought. Also, the calculated values are stored in the dataset and can be shared with researchers by request. As a simple index, results indicated that CWRID can be used to quantify the impacts of drought on agricultural as it can reflect the variation of crop yields.

How to cite: sun, H. and Chen, J.: An index to quantifying the impacts of agricultural drought and its application in China, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-1041, https://doi.org/10.5194/egusphere-egu2020-1041, 2020.

There are evidences that climate change as a result of both natural and anthropogenic processes has exacerbated the frequency and the severity of flood hazards over past decades across the world. Moreover, changes in the pattern of precipitation and temperature during the 21st century are expected to induce region-specific impacts on floods, especially increase in local floods in some catchments. However, the future is hard to predict as there are strong discrepancies in how climate change is expected to affect runoff and river discharge at different places. Many studies have proven that not only climate, socio-economic and physical factors such as elevation and soil type are determinant for flood risk characterisation. Anthropogenic activities and impacts through land use and land cover degradation have substantial implication for hydrological processes. Moreover, catchment management play an important role in sustainable flood management which is generally based on technical knowledge. But it must also be socially and politically meaningful. This is especially relevant for transboundary catchments where riparian countries might offer different economic, social and political environment, and hence have distinct approaches of flood risk reduction and management. An effective cooperation between states sharing transboundary water resources must include a continuum comprised of data exchange, information sharing, collaboration and joint action. It is a search for cooperative management while respecting the sovereignty of each state. There is a variety of methods used for assessing transboundary management and identifying cooperative strategies. Among others, the following ones can be mentioned: the Water Cooperation Quotient, the multiobjective analysis, hydropolicy simulation models, the Multiobjective Evolutionary Algorithms (MOEAs) and a combination of the two later. Hence this study aims at exploring various approaches of transboundary management and analyses experienced over the world. Lessons will afterward be drawn in the context of climate and land use change in the transboundary Mono River catchment shared by the Republics of Benin and Togo.

How to cite: Houngue, R., Evers, M., and Almoradie, A.: Impacts of Climate and Land Use Change in the Management of a Transboundary Basin- Case Study of Mono River catchment, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-1145, https://doi.org/10.5194/egusphere-egu2020-1145, 2020.

EGU2020-1207 | Displays | HS1.2.4

Drying Lakes: A Review on The Health Conditions and Restoration Strategies

Anchita Anchita, Kamshat Tussupova, and Peder Hjorth

Abstract: Decrease of saline lakes, which comprises of 44% of all the available lake water, is a major concern. It additionally brings to desertification process to the region. Thus, various countries have taken different actions in protecting their lake’s water level. The aim of this paper is to assess different strategies directed to tackle the decreasing saline lake water levels. Lake Urmia and the Aral Sea which split into North Aral and South Aral were among the world's largest saline lakes and now have reduced to 10% of their original size. A thorough review of academic reports, official documents and databases were considered. Although the dry-up of the lake is a natural process, it has been sped up by human interventions in the hydrology cycle. Dust storms (strong winds) in the case of the Aral Sea, transmit the pollutants from dry lake surface which initially accumulated in the lakebed causing severe health issue. Various strategies were implemented to manage the socio-economic conditions caused due to the drying of lakes. The strategy implemented for the North Aral Sea was to restore the lake by reducing the water withdrawal from tributary rivers which leads to increased water level in the sea. The strategy implemented for Lake Urmia was to restore the lake by water transfer activities from neighbouring water sources which until now show no increase in water level. The strategy implemented for the South Aral Sea was to use a dry lakebed to diversify the economy by oil and mineral extraction which shows the adaptation to the environmental conditions with no restoration strategy. As a conclusion, it is found that there is no common best solution for this kind of problem. The best fit depends on the local context and it is strongly path dependent. 

Keywords: Drying saline lake; Dust storms; Aral sea; Health impacts; Lake Urmia; Restoration of saline lake; Strategies.

How to cite: Anchita, A., Tussupova, K., and Hjorth, P.: Drying Lakes: A Review on The Health Conditions and Restoration Strategies, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-1207, https://doi.org/10.5194/egusphere-egu2020-1207, 2020.

EGU2020-6201 | Displays | HS1.2.4

Interactions and feedbacks between water availability and domestic consumption in São Paulo Metropolitan Area

Felipe Souza, Gabriela Gesualdo, Murugesu Sivapalan, and Eduardo Mendiondo

Water supply in large cities has challenged governments and water authorities because of the complexity involved in meeting water demands. The traditional challenges stem from the seasonality of precipitation and population growth. Although water resources management strategies assume potential scenarios for water demand growth to design water infrastructure, unexpected changes in the hydrological cycle may cause shocks to urban water supply systems and generate unanticipated patterns of consumption, such as occurred during the water crisis experienced by the São Paulo Metropolitan Area (SPMA) from 2014 to 2016. This work explores the coevolution of the coupled human-water system variables associated with the water supply system within the SPMA, from the late twentieth century to the present, to explain how water demand has influenced water availability, and vice-versa, in particular for the Cantareira Reservoir System. The challenges facing the human-water system in the region are of critical importance, given that it supplies water to more than 9 million people, and it supports economic activities that represent 12% of Brazil’s Gross Domestic Product. The analysis reveals that hydrological shifts are responsible for major structural transformations and they also have led to changes in domestic consumption. We conclude that modelling the interactions and feedbacks between water availability and consumption can provide more realistic storylines to implement strategies to address water scarcity than merely considering long-term demand scenarios, as it is normally done. In addition, policies implemented to promote water savings can have different responses at sub-regional scales and this can be explored also in the context of long-term scenarios.

How to cite: Souza, F., Gesualdo, G., Sivapalan, M., and Mendiondo, E.: Interactions and feedbacks between water availability and domestic consumption in São Paulo Metropolitan Area, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-6201, https://doi.org/10.5194/egusphere-egu2020-6201, 2020.

EGU2020-7040 | Displays | HS1.2.4

Lost in the waters: contemporary dilemmas in examining transboundary water interaction

Richard Grünwald, Yan Feng, and Wenling Wang

The presented paper examines current dilemmas in transboundary water interaction and debates about the reconceptualization of the Transboundary Water Interaction Nexus (TWINS). The new TWINS framework provides a theoretical alternative how to (1) evaluate the interstate relations between two or more actors regardless their legal status; (2) calculate the transboundary water interaction based on process tracing analysis rather than milestone analysis; (3) distinguish more intensities of cooperation and conflict, (4) clarify broader hydropolitical context in transboundary water interaction, and (5) debate about dual water event phenomenon where one event may possess both cooperation and conflict features. Currently, the new TWINS model serves as an indicator for evaluating cooperation and conflict intensity of water-related events in the Lancang-Mekong River Basin. The data are then recorded in the Lancang-Mekong Cooperation and Conflict Database (LMCCD) designed by authors which already comprise more than 1600 water-related events in the last 30 years (1990-2020). To proof the viability of the presented concept, we will illustrate the new TWINS model on a case study related to the Xayaburi hydropower dam. Although there are still several methodological limitations, the new TWINS model can be adapted to any interstate water-related issue and be able to fill the information gaps about the interdisciplinary understanding of the transboundary water interaction.

How to cite: Grünwald, R., Feng, Y., and Wang, W.: Lost in the waters: contemporary dilemmas in examining transboundary water interaction, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-7040, https://doi.org/10.5194/egusphere-egu2020-7040, 2020.

EGU2020-7148 | Displays | HS1.2.4

Socio-hydrological approach to understand conflict and cooperation dynamics in transboundary rivers

jing wei, Mohammad Ghoreishi, Felipe Souza, You Lu, and Fuqiang Tian

Transboundary river basins share a complex network of environmental, economic, political, social and security interdependencies. Consequently, transboundary river systems are characterized by evolving conflict and cooperation dynamics between riparian states. The current literature on transboundary watersheds does not identify the key feedback loops between interconnected political, cultural, institutional and socioeconomic factors. This work compares sociohydrological models of three transboundary rivers (Nile River, Columbia River, and Lancang-Mekong River) with distinct characteristics in terms of hydrological processes and socioeconomic conditions. Conflict/cooperation dynamics within these three models were found to be driven by hydrological regime, economic benefits, power imbalance and institutional capacity. By comparing the contextual factors of the emergent conflict/cooperation dynamics across these three river basins, our synthesis study aims to present a general framework that explains how conflict/cooperation dynamics emerge from the interaction between human and hydrological systems.

How to cite: wei, J., Ghoreishi, M., Souza, F., Lu, Y., and Tian, F.: Socio-hydrological approach to understand conflict and cooperation dynamics in transboundary rivers, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-7148, https://doi.org/10.5194/egusphere-egu2020-7148, 2020.

The river Maltsch / Malše is an interesting waterbody from a historical, hydrological and ecological perspective. As a border river between Austria and the Czech Republic, it has had an eventful history. With the political separation into “East” and “West” in the middle of the 20th century, a region that initially had a similar land use structure was completely changed. On the Czech side, villages and settlements were removed and the land expropriated. In the course of the fall of the Iron Curtain, the land was mostly sold to large landowners. Changes also took place on the Austrian side. Agriculture and forestry have been intensified over decades.

This leads to the situation that on both sides of the river, under very similar geological and hydrological conditions, the effects of very different land use developments and changes on the water household and erosion can be documented. Thus, a transboundary, mainly EU-funded INTERREG project was launched to investigate this variability in general and to address the implications for the sediment regime in such river systems (concerning e.g. flood protection control, sedimentation of reservoirs) in specific. Moreover, it is examined how mitigation measures for water retention, erosion control and climate change adaption can be planned under these variable boundary conditions. Especially droughts and heavy rainfall events must be considered as threats in the region in the future.

In addition to the changes described above, the political situation in the border region has left a refuge for nature. The Maltsch is part of the so-called Green Belt that stretches across the whole of Europe. A key species of the region is the Freshwater Pearl Mussel (Margaritifera margaritifera), which is characterised by its very high demands on the environment. It, therefore, serves very well as an indicator / umbrella species and thus also as a condensation nucleus of the different topics of the project.

In summary, the following aspects will be presented: (1) documentation of historic, political driven land use changes and land use differences on GIS basis, (2) effects on soil erosion by means of modelling via USLE, (3) estimation of the effects on the landscape hydrology and (4) effects on the aquatic fauna, especially the key species Freshwater Pearl Mussel.

How to cite: Höfler, S., Ringler, G., Gumpinger, C., and Hauer, C.: Land use changes at the former “Iron curtain” and their implications for catchment hydrology, erosion and ecology – a transboundary project between Austria and Czech Republic, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-9012, https://doi.org/10.5194/egusphere-egu2020-9012, 2020.

EGU2020-9166 | Displays | HS1.2.4

Evaluation of 2018 drought and effectiveness of adaptation measures in the Netherlands

Marjolein H.J. van Huijgevoort, Janine A. de Wit, and Ruud P. Bartholomeus

Extreme dry conditions occurred over the summer of 2018 in the Netherlands. This severe drought event led to very low groundwater  and surface water levels. These impacted several sectors like navigation, agriculture, nature and drinking water supply. Especially in the Pleistocene uplands of the Netherlands, the low groundwater levels had a large impact on crop yields and biodiversity in nature areas. Projections show that droughts with this severity will occur more often in the future due to changes in climate. To mitigate the impact of these drought events, water management needs to be altered.

In this study, we evaluated the 2018 drought event in the sandy regions of the Netherlands and studied which measures could be most effective to mitigate drought impact. We have included meteorological, soil moisture and hydrological drought and the propagation of the drought through these types. Droughts were determined with standardized indices (e.g. Standardized Precipitation Index) and the variable threshold level method. Investigated measures were, for example, higher water levels in ditches, reduced irrigation from groundwater, and increased water conservation in winter. We also studied the timing of these measures to determine the potential for mitigating effects during a drought versus the effectiveness of long term adaptation. The measures were simulated with the agro-hydrological Soil–Water–Atmosphere–Plant (SWAP) model for several areas across the Netherlands for both agricultural fields and nature sites.

As expected, decreasing irrigation from groundwater reduced the severity of the hydrological drought in the region. Severity of the soil moisture drought also decreased in fields that were never irrigated due to the effects of capillary rise from the groundwater, but, as expected, increased in currently irrigated fields. Increasing the level of a weir in ditches had a relatively small effect on the hydrological drought, provided water was available to sustain higher water levels. This measure is, therefore, better suited as a long term change than as ad hoc measure during a drought. The effectiveness of the measures depended on the characteristics of the regions; for some regions small changes led to increases in groundwater levels for several months, whereas in other regions effects were lost after a few weeks. This study gives insight into the most effective measures to mitigate drought impacts in low-lying sandy regions like the Netherlands.

How to cite: van Huijgevoort, M. H. J., de Wit, J. A., and Bartholomeus, R. P.: Evaluation of 2018 drought and effectiveness of adaptation measures in the Netherlands, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-9166, https://doi.org/10.5194/egusphere-egu2020-9166, 2020.

EGU2020-9245 | Displays | HS1.2.4

Analyzing the Impacts of Urbanization on Watershed Streamflow Characteristics

Qining Shen and Zhentao Cong

It is widely recognized that urbanization has a significant impact on streamflow characteristics. However, the influences of economic development, increasing population and positioning of urban development on streamflow regimes is still not fully understood. This study aims to clarify these influences by analyzing 134 catchments in China and 1064 catchments in the United State. Urbanization metrics were derived from gridded GDP dataset, gridded population dataset and land use/land cover datasets, while the streamflow characteristics were calculated using annual streamflow and mean daily discharge data. The statistical analysis indicated that the rate of change in rainfall-runoff ratio is positively related to the growth rate of GDP and urban area both in China and the U.S., but this relationship was not found in population growth rate. Increasing the extent of urbanized area increased high and low flow frequency in Kansas metropolitan region as well as San Antonio metropolitan region, while reduced low flow frequency in Atlanta metropolitan region. In addition, urban expansion also enhanced streamflow flashiness. Compared to down-stream development, up-stream development increased high flow volume in Atlanta metropolitan region and Kansas metropolitan region, while decreased high flow volume in San Antonio metropolitan region and low flow volume in all study metropolitan regions. The findings in this study provide a sight for future researches in hydrological variation due to urbanization.

How to cite: Shen, Q. and Cong, Z.: Analyzing the Impacts of Urbanization on Watershed Streamflow Characteristics, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-9245, https://doi.org/10.5194/egusphere-egu2020-9245, 2020.

EGU2020-12073 | Displays | HS1.2.4

Scenario Analysis of Cooperation Dynamics on the Columbia River under Changing Conditions using Socio-Hydrological Modelling

Charlotte Cherry, Felipe Augusto Arguello Souza, Samuel Park, Ashish Shrestha, Liu Yang, Marlies Barendrecht, Margaret Garcia, David Yu, Jing Wei, and Fuqiang Tian

The Columbia River Treaty, signed in 1961, solidifies cooperation between the United States and Canada to manage the operation of the Columbia River’s extensive dam network jointly to optimize benefits for the whole system. Under the treaty, Canada operates dams to provide flood protection and maximize hydropower potential downstream. In exchange, the U.S. compensates Canada with half of the estimated benefits of the treaty, which provides an economic incentive to cooperate not seen in many other transboundary basins. However, since the treaty was established, this highly-managed system has responded to unanticipated external social and environmental factors. For example, mounting social pressure in the 1990s to protect the aquatic environment resulted in operational changes to U.S. dams to accommodate flows for fish migration, which ultimately resulted in financial losses for hydropower producers. These changes affected the relative benefits each country receives from cooperation. Utilizing a range of hydrological, economic, social, and environmental datasets, a socio-hydrological model was developed that simulates system operations using historical data to mimic operational changes, shifts in flood control and hydropower production, and cooperation dynamics.

Renegotiations of the Columbia River Treaty started in 2018, and the new treaty in 2024 must include provisions for environmental protection that were, originally, not considered. The purpose of this study is to use the established model to envision how changing conditions such as climate change, spring fish flows, and First Nation rights would affect each country’s willingness to cooperate. For example, how would changes in snowpack upstream or seasonal changes in precipitation alter the hydrology of the basin and, in turn, the benefits each country receives from cooperation. This scenario analysis provides insight into how a revised treaty that takes future uncertainties into account would affect the balance of benefits to maintain or disrupt cooperation on the Columbia River.

How to cite: Cherry, C., Souza, F. A. A., Park, S., Shrestha, A., Yang, L., Barendrecht, M., Garcia, M., Yu, D., Wei, J., and Tian, F.: Scenario Analysis of Cooperation Dynamics on the Columbia River under Changing Conditions using Socio-Hydrological Modelling , EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-12073, https://doi.org/10.5194/egusphere-egu2020-12073, 2020.

EGU2020-12550 | Displays | HS1.2.4

Reducing Water Scarcity by Improving Water Productivity

Landon Marston, Gambhir Lamsal, Zachary Ancona, Peter Caldwell, Brian Richter, Benjamin Ruddell, Richard Rushforth, and Kyle Davis

Nearly one-sixth of US river basins are unable to consistently meet societal water demands while also providing sufficient water for the environment. Water scarcity is expected to intensify and spread as populations increase, new water demands emerge, and climate changes. Improving water productivity by meeting realistic benchmarks for all water users could allow US communities to expand economic activity and improve environmental flows. Here we utilize a spatially detailed database of water productivity to set realistic benchmarks for over 400 industries and products. We assess unrealized water savings achievable by each industry in each river basin within the conterminous US by bringing all water users up to industry- and region-specific water productivity benchmarks. Some of the most water stressed areas throughout the US West and South have the greatest potential for water savings, with around half of these water savings obtained by improving water productivity in the production of corn, cotton, and alfalfa. By incorporating benchmark-meeting water savings within a national hydrological model (WaSSI), we demonstrate that depletion of river flows across Western US regions can be reduced on average by 6.6%-23.5%, without reducing economic production. Lastly, we employ an environmentally-extended input-output model to identify the US industries and locations that can make the biggest impact by working with their suppliers to reduce water use “upstream” in their supply chain. The agriculture and manufacturing sectors have the largest indirect water footprint due to their reliance on water-intensive inputs but these sectors also show the greatest capacity to reduce water consumption throughout their supply chains.

How to cite: Marston, L., Lamsal, G., Ancona, Z., Caldwell, P., Richter, B., Ruddell, B., Rushforth, R., and Davis, K.: Reducing Water Scarcity by Improving Water Productivity, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-12550, https://doi.org/10.5194/egusphere-egu2020-12550, 2020.

EGU2020-13100 | Displays | HS1.2.4

Conflict and Cooperation Analysis on Transboundary River Basins Using News Media Text Mining Approach

Liying Guo, Fuqiang Tian, Jing Wei, and You Lu

Transboundary water problems are complex systems, which involve interdependence and interconnectedness between elements, uncertainty and feedbacks between processes, and emergence and adaptation through evolution of the systems. There is nearly no way to formulate transboundary water problems in an equation fitting-one-size-for-all. As nature-human coupled systems, transboundary water problems should consider actual stakeholders and parties in context-specific situations as well as natural conditions.

News media are good recorders for us to have an insight into the transboundary water problems down-to-earth. Local news media are the first-hand and direct reflections of societal values among the riparian countries and stakeholders, and are documentaries of what is going on in transboundary river basins. International news media are also good sources to know about how people in the world perceive transboundary river issues from the perspectives as “outsiders”. Therefore, text analysis of news articles concerning conflict and cooperation on transboundary river basins can tell us a whole story about the past history and on-going “real” life in the basins.

To uncover the patterns and dynamics of conflictive and cooperative events on a global scale, people usually read news articles, extract information manually in the past, which is tedious and time-commanding. In the era of big data, we collect large news media datasets automatically, and employ machine learning techniques to do data mining out of those news media data. The aim of our research is to minimize manual labor in searching, filtering, reading and understanding the related news media articles by computer, and to provide potent tools for researchers to retrieve useful information  in the related areas. To validate our methodology, we look Mekong River Basin and Brahmaputra River Basin as case studies into details. To apply our methodology in a global scale, we intend to draw a world map with a timeline to show how water conflict, and cooperation occurs, grows, and transforms. By capturing characteristics of the life cycles of water conflict and cooperation, we aim to throw light upon water management in transboundary river basins, provide some hints for water resources decision-makers, and enhance global water security.

How to cite: Guo, L., Tian, F., Wei, J., and Lu, Y.: Conflict and Cooperation Analysis on Transboundary River Basins Using News Media Text Mining Approach , EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-13100, https://doi.org/10.5194/egusphere-egu2020-13100, 2020.

EGU2020-13368 | Displays | HS1.2.4

Drivers of water conflicts in co-evolving human-water systems in Cauvery Basin, Southern India

Veena Srinivasan, Neha Khandekar, and Ganesh Shinde
 
​India is a rapidly evolving economy with rising demands from various sectors and stakeholders including the environment.  Water conflicts emerge when mechanisms to allocate water between different sectors do not keep up with changing demands. 
 
Because biophysical drivers of water availability such as industrialization, urbanization, and deforestation are driven by humans - integration of underlying socio-economic drivers with bio-physical in is, therefore, understanding water conflicts requires a socio-hydrological approach.
 
In an attempt to understand this dynamism of human-water interactions within the landscape and improve the emergence of water conflicts, we present the case of the Cauvery basin -- a highly contentious inter-state river basin in Southern India. Over a two-decade period, we explore how catchments have co-evolved by studying signatures of 53 watersheds in Cauvery basin and correlate it to the occurrence of conflict in print media. Using spatiotemporal cluster statistical analyses tools like principal component analysis in R, we explore how changes in the landscape have triggered water conflicts.

How to cite: Srinivasan, V., Khandekar, N., and Shinde, G.: Drivers of water conflicts in co-evolving human-water systems in Cauvery Basin, Southern India, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-13368, https://doi.org/10.5194/egusphere-egu2020-13368, 2020.

EGU2020-13519 | Displays | HS1.2.4

AGEO – Natural hazard prevention and awareness raising through citizen observatories.

Ariadna Ortega Rodriguez, Rui Carrilho Gomes, Filipe Telmo Jeremias, Juan Carlos Santamarta Cerezal, Lidia Quental, Inés Galindo Jiménez, Vitor Correia, Cláudia Narciso Pinto, Nicolas Le Dantec, Fátima Gouveia, Kirstin Lemon, Alain Hénaff, and Gregory O’Hare

The Platform for Atlantic Geohazard Risk Management (AGEO) is a new project co-financed under the Interreg Programme for the Atlantic Area which aims to launch five Citizens’ Observatory pilots on geohazards according to regional priorities:

  • Citizens’ observatory on rockfalls and rockfall-triggers in the Canary Islands, Spain
  • Peat-slides and peat massmovement monitoring and control in Cuilcagh Mountain, Northern Ireland
  • Multihazard Citizens’ Observatory in Lisbon, Portugal
  • Citizens’ observatory of slope instability monitoring along the Cliffs of Moher, Ireland
  • Citizens’ observatory of vulnerability to coastal Risks in Brittany, france

These will demonstrate how citizens’ involvement in geohazard risks prevention can strengthen regional and national risk management systems. Instituto Superior Técnico (Portugal) leads the consortium of AGEO that also counts with several other partners from Portugal, Spain, France, Ireland and the United Kingdom.

AGEO will engage with local communities to actively participate in risk preparedness and monitoring and incorporate local capacities into risk management systems. Experiences gained during the implementation of the Citizens’ Observatory pilots will be used to formulate recommendations for the creation of future observatories in response to the widest range of hazards (both natural and human-induced) faced in the Atlantic region.

The Observatories are part of the phenomenon of citizen science.  As defined by the EC, “Citizens' Observatories are community-based environmental monitoring and information systems. They build on innovative and novel Earth observation applications embedded in portable or mobile personal devices.  This means that citizens can help and be engaged in observing our environment.”

There are many other definitions, as it is still a novel concept, but for this project the one above will be used. It is an observatory in a sense that we need careful monitoring of the risks that will be defined per region in line with a set of parameters to be defined through engaging with participating citizens to be filled in by the participating citizens. This approach lends the opportunity of collecting large amounts of data for very little to no money with the added bonus of the territorial coverage such approach can grant. Additionally, spatial data infrastructures and services already in place, e.g. Copernicus, will support the assessment and monitoring of geohazards and risk management systems.

AGEO is also organizing workshops in each participating region to ensure the citizens understand the role they play in preventing and mitigating natural risks by being part of the observatories and hopefully encouraging new members to join. These workshops will be held in the national language of the region and are to be tailored to the different audiences and will democratize the use of the observatories by listening to the people using them and taking into account their needs.

 

 

How to cite: Ortega Rodriguez, A., Carrilho Gomes, R., Telmo Jeremias, F., Santamarta Cerezal, J. C., Quental, L., Galindo Jiménez, I., Correia, V., Narciso Pinto, C., Le Dantec, N., Gouveia, F., Lemon, K., Hénaff, A., and O’Hare, G.: AGEO – Natural hazard prevention and awareness raising through citizen observatories., EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-13519, https://doi.org/10.5194/egusphere-egu2020-13519, 2020.

EGU2020-17936 | Displays | HS1.2.4

Effects of Interactions Between Society and Environment on Policy in Water Resources Management: Exploring Scenarios of Natural and Human-Induced Shocks

Iolanda Borzì, Murugesu Sivapalan, Brunella Bonaccorso, and Alberto Viglione

In many regions of the world, water supply is threatened by natural hazards such as floods and droughts, as well as by shocks induced by anthropogenic changes to water use. Lack of anticipation and/or preparation for these events can lead to delayed or insufficient responses to sudden or developing water crises, that sometimes can produce irrecoverable damage to the environment. In this work, a socio-hydrological approach to sustainable water resources management of the Alcantara River Basin in Sicily (Italy) is adopted that explicitly takes into account feedbacks between the natural and the human components that might arise from shocks to the water management system, including possible evolution of policy responses. The Alcantara River Basin is a groundwater-fed catchment which supplies many villages on the Ionian coast up to Messina city, mainly through the Alcantara aqueduct, but also agricultural areas and industries, including hydropower plants. It also hosts the Alcantara Fluvial Park, an important natural reserve. The Alcantara aqueduct also supplied the city of Messina during a temporary failure of its main aqueduct caused by a landslide in October 2015. The main purpose of the work is to use the socio-hydrological model as a “screening tool” to frame water resource management issues in a broad way and provide guidance to the community to identify aspects of societal behavior that need to evolve towards sustainable water resource management in order to withstand future shocks. This has been done by scenario simulations in conditions of a natural shock affecting the system (i.e. drought) and of a human-induced one (i.e. increase in groundwater extraction). Sensitivity analysis of the model social parameters revealed how the value attributed by the society to the environment and water resources use, its capacity to remember previous water crises and, in particular, its previous responses to shocks, can affect the system in a way that can produce paradoxical effects. Results show how a rapid decision-making strategy that may work in the short term, can be counter-productive when viewed over the long term and how a do-nothing decision during a water crisis could be highly damaging to the environment. For the above-mentioned reasons, this socio-hydrological approach can be considered as a useful tool to understand human-water dynamics and to support decision-makers in water resource management policies with a broad and long-term perspective.

How to cite: Borzì, I., Sivapalan, M., Bonaccorso, B., and Viglione, A.: Effects of Interactions Between Society and Environment on Policy in Water Resources Management: Exploring Scenarios of Natural and Human-Induced Shocks, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-17936, https://doi.org/10.5194/egusphere-egu2020-17936, 2020.

EGU2020-18711 | Displays | HS1.2.4

From Fear to Hope: The inspiring journey of an 11-year-old Environmental Activist

Florence Halstead, Lucie Parsons, and Katie Parsons

"When I first became aware of the destruction of the world through climate change, I felt very upset and angry, but also a little worried.  What was going to happen to my world? And what was everyone going to do about it, including me?” (Parsons, 2019).

The Earth is currently undergoing a sixth global scale ecological crisis. The available science almost unanimously positions human activity at the heart of the cause of this crisis, with anthropogenic emissions of greenhouse gasses, pollution, land degradation and deforestation, all contributing. Recent IPCC reporting has demonstrated a need to curb global warming at 1.5 degrees above the pre-industrial baseline and have highlighted a range of likely impacts of Climate Change should no action be taken, particularly in relation to reducing greenhouse gas emissions to net zero by 2050. Despite this need, policy-based action at a nation state level is largely lacking, with recent talks at COP25 failing to reach agreements. However, a significant global youth movement is now underway, with children and young people taking it upon themselves to highlight a need for climate and environmental action, calling for others to follow. Greta Thunberg and the Fridays For Future (#FFF) movement now regularly appears in mainstream media, highlighting the issues of Climate Change with an emotive narrative centred on the impact of future climate change on today’s children and their environments.

Whist there is growing literature that explores Youth Activism, to our knowledge, there is no investigation that has followed the emotional journey of a child whom has chosen to take environmental action. Here, we present Lucie Parsons, an 11-year old girl who, after watching BBC’s Blue Planet II back in 2017 and seeing the devastation plastic pollution was having on the marine environment and its wildlife, decided to take action and be a champion for positive environmental change. Since then, Lucie has spoken at international conferences, conducted her own research in her primary school, organised regional litter picks, and has become an Ambassador for the national charities iWill and Kids Against Plastic; amongst many other things. As her activism has gained momentum and as she has become more aware of wider environmental issues, her focus on plastic pollution has broadened to include the current climate crisis and environmental degradation as a whole. We will present the highs and lows of Lucie’s Environmental Activism and the role that emotion has played in her journey thus far; as well as what she believes to be the achievements in her own science communication and what you as scientists can do to help her in her fight against environmental and climatic change.

 

How to cite: Halstead, F., Parsons, L., and Parsons, K.: From Fear to Hope: The inspiring journey of an 11-year-old Environmental Activist, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-18711, https://doi.org/10.5194/egusphere-egu2020-18711, 2020.

EGU2020-19092 | Displays | HS1.2.4

Conceptualizing trade-offs of water conservation strategies and unintended consequences using a system dynamics approach

Vincent Odongo, Giuliano Di Baldassarre, and Maurizio Mazzoleni

Improving water use efficiency in agriculture is a key strategy in reducing water scarcity, especially during drought seasons. However, the benefits of these water saving strategies can be reduced if farmers switch to more profitable and water consuming crops or increasing irrigable area, i.e. rebound effects. These feedbacks will likely offset the water savings benefits and subsequently intensify agricultural water use. Here we propose a new system dynamic model that represents the interactions and feedback loops between hydrological and social processes to explore rebound effects by analysing competing water needs for both urban and agricultural allocation. The model is then used to explore the dynamics of different mitigation policy options to alleviate the phenomenon: (i) Restricting water allocation (ii) Limiting size of agricultural land (iii) Changing cropping patterns (iv) Deficit irrigation.

 

How to cite: Odongo, V., Di Baldassarre, G., and Mazzoleni, M.: Conceptualizing trade-offs of water conservation strategies and unintended consequences using a system dynamics approach, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-19092, https://doi.org/10.5194/egusphere-egu2020-19092, 2020.

EGU2020-19969 | Displays | HS1.2.4

Perceiving and managing the 2018 & 2019 droughts in Europe: is there a need for macro-governance in Europe?

Veit Blauhut, Claudia Teutschbein, Mathias N. Andersen, Manuela Brunner, Carmelo Cammalleri, Ksenija Cindrić Kalin, David C. Finger, Marijke Huysmans, Kiril Manevski, Marzena Osuch, Renata J. Romanowicz, Kerstin Stahl, Michael Stoelzle, Anne F. Van Loon, Michelle T.H. Van Vliet, Niko Wanders, Jürgen Vogt, Jean-Philippe Vidal, and Patrick Williams

In recent years, the adverse effects of drought have been experienced and perceived more severely and frequently all over Europe. These impacts are a result of the drought hazard and the socio-economic and ecological vulnerability. Due to the heterogeneity of Europe’s hydro-climatology and its cultural, political, social and economic diversity , the socio-economic and ecological impacts vary not only with respect to the extent, duration and severity of the drought, but also with the characteristics of affected societies, economic sectors and ecosystems. 

The lack  of understanding the spatio-temporal differences in the drivers of drought risk hinders the successful mitigation of future impacts, and the design of suitable reactive and proactive drought action plans. Therefore, this study describes the European drought events of 2018 and 2019 beyond the hazard. The hypothesis to be proven is that similar hazard conditions result in different impacts due to national and sub-national differences in drought vulnerability, perception and drought-risk management. Based on research in 35 European countries, comparable national datasets on drought management and perception are established. For each of these countries, a uniform questionnaire was distributed to water management-related stakeholders at different administrative levels. A major focus of the questions was the perception and impacts of the recent droughts and current management strategies on a national and sub-national scale. The results of the questionnaires are also compared to country-scale profiles of past drought events for different drought types, i.e. meteorological, soil moisture, hydrological and vegetation drought, which were established based on information derived from the European Drought Observatory indicator system.

The results highlight a large diversity in the national perception of drought as a natural hazard and its impacts; but also a different spatial extent of 2018/2019 drought events At the same time,  existing drought management strategies are shown to increase national and sub-national resilience. The study, therefore, calls for international exchange and mutual learning to improve national and international drought governance and management.

How to cite: Blauhut, V., Teutschbein, C., Andersen, M. N., Brunner, M., Cammalleri, C., Cindrić Kalin, K., Finger, D. C., Huysmans, M., Manevski, K., Osuch, M., Romanowicz, R. J., Stahl, K., Stoelzle, M., Van Loon, A. F., Van Vliet, M. T. H., Wanders, N., Vogt, J., Vidal, J.-P., and Williams, P.: Perceiving and managing the 2018 & 2019 droughts in Europe: is there a need for macro-governance in Europe?, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-19969, https://doi.org/10.5194/egusphere-egu2020-19969, 2020.

EGU2020-21060 | Displays | HS1.2.4

Intra-year distribution of water discharge in global rivers

Yao Yue and Yuanfang Chai

Intensive human interference, climate variability, and ongoing climate change affect the seasonality of runoff processes in rivers worldwide, which in turn may promote more frequent extreme flow events and cause irreversible damage to the ecological environment. Here we examine the global trend of the intra-year distribution of the seaward water discharge in 314 independent river basins, the total drainage area of which accounts for 2/3 of the total Earth land. The results show that the intra-year distribution of water discharge is homogenized between dry and flood seasons in 181 river basins, such as the Nile, Mississippi, Yangtze, Ganges, etc., but polarized in 39 basins, e.g. Amazon, Zaire, and Niger. Considering the primary factors affecting the intra-year distribution of water discharge, i.e. precipitation (P), evaporation (E), glacial runoff (G), and dam operations (D), the global river basins can be divided into GDEP, DEP, GEP, and EP types. Using the stepwise regression method, quantitative contributions of each factors to either homogenization or polarization phenomena are calculated. It is found that the homogenization of water discharge is mainly controlled by dam operations in GDEP and DEP river basins, but dominated by the homogenized precipitation in GEP and EP river basins. Homogenized evaporation and polarized precipitation are the major factors behind the polarization of water discharge. This work is of importance to flood/drought disasters control and sustainable riverine/coastal eco-system management.

How to cite: Yue, Y. and Chai, Y.: Intra-year distribution of water discharge in global rivers, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-21060, https://doi.org/10.5194/egusphere-egu2020-21060, 2020.

EGU2020-21922 | Displays | HS1.2.4

On the dark side of the earth – How the Black Marble Alliance supports humanitarian activities with satellite-derived night-time light observations

Markus Enenkel, Miguel Román, Eleanor Stokes, Shrestha Ranjay, and Vinck Patrick

Various satellite data are part of humanitarian decision-making workflows. The added value of daytime imagery is mostly obvious, contributing to damage and needs assessment or the monitoring of populations of concern among other applications. However, the development and practical humanitarian applications of night-time imagery are largely unexplored. New possibilities are emerging with the public release of NASA’s black marble dataset – a global nighttime lights product derived from the Visible Infrared Imaging Radiometer Suite (VIIRS) on-board the Suomi National Polar-orbiting Partnership (NPP) satellite. Emerging evidence demonstrates the added-value of the black marble dataset to assess disaster impact and displacement after cyclone Idai made landfall in Mozambique in March 2019. Similar data was used to monitor reconstruction efforts in Puerto Rico in the wake of hurricane Maria's landfall in 2017, uncovering socio-economic inequalities in electricity restoration efforts. This work is led by a unique collaboration between the Universities Space Research Association’s (USRA) Earth from Space Institute, NASA Goddard Space Flight Center, Harvard Humanitarian Initiative, the World Bank, logistics services companies, aid and development organizations. 

How to cite: Enenkel, M., Román, M., Stokes, E., Ranjay, S., and Patrick, V.: On the dark side of the earth – How the Black Marble Alliance supports humanitarian activities with satellite-derived night-time light observations, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-21922, https://doi.org/10.5194/egusphere-egu2020-21922, 2020.

HS1.2.6 – Hydrologic Dynamics, Analytics and Predictability: Physical and Data-based Approaches for Improving Hydrologic Understanding and Prediction

EGU2020-10073 | Displays | HS1.2.6

Stochastic time-dependent parameters to improve the modeling and characterization of catchments

Marco Bacci, Fabrizio Fenicia, and Jonas Sukys

Catchments are complex dynamical systems exposed to highly-variable inputs (rainfall). Despite this complexity, it is uncommon to model these systems as stochastic ones. Previous works offer a large number of examples where deterministic (conceptual or physics-based) models are used to describe hydrological basins in spite of the fact that, in some cases, the output of the model shows substantial deviations from the observed data even after meticulous calibration.
There are different ways to include stochasticity in the hydrological modeling of catchments. With this contribution we explore a systematic way to improve our knowledge of the system at hand by using time-dependent parameters, which are driven by suited stochastic processes. The fundamental idea, which dates back to seminal works carried out about ten years ago, is to correlate the evolution of the selected time-dependent parameters to catchment features, input variables, or possible changes over time within the catchment area, to improve the structure of the model in a data-driven fashion, rather than to merely resort to including a bias term on the output of the model.
In doing so for different catchments, we make use of a newly-developed inference framework called SPUX, which is particularly suited to deal with non-linear stochastic models as it enables the usage of high-performance computing clusters for (Bayesian) inference coupled with the particle filter method. This allows us to explore and show our approach at work on different settings, such as models of different complexity and data-sets of different resolutions, lengths, and relevant to catchments with different characteristics, which have (or not) changed over time.

How to cite: Bacci, M., Fenicia, F., and Sukys, J.: Stochastic time-dependent parameters to improve the modeling and characterization of catchments, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-10073, https://doi.org/10.5194/egusphere-egu2020-10073, 2020.

EGU2020-10958 | Displays | HS1.2.6

Scale-Dependent Worth of QPF for Real-Time Streamflow Forecasting

Witold Krajewski and Ganesh Ghimire

The authors explore uncertainty associated with the quantitative precipitation forecasts (QPF) and its implication to the predictability of real-time streamflow forecasts. Including rainfall forecasts into real-time streamflow forecasting system extends the forecast lead time. As rainfall is a key driver of rainfall-runoff models both past and future rainfall estimates should be used in streamflow and flood forecasting. Since both QPE and QPF are subject to substantial uncertainties, questions arise on the trade-off between the time horizon of the QPF and the accuracy of the streamflow forecasts. Particularly QPF is notorious for its significant uncertainty with respect to location, timing and magnitude. Operational hydrologic services often limit their use of the QPF to one or two days into the future. The authors study this problem systematically using operational models and QPF. Their focus is on scale-dependence of the trade-off between the QPF time horizon and streamflow accuracy. To address this question, the authors first perform comprehensive independent evaluation of QPF at about 140 basins with wide range of spatial scales (10 - 40000 km2) corresponding to U.S Geological Survey (USGS) streamflow monitoring stations over the state of Iowa in Midwestern United States. High Resolution Rapid Refresh (HRRR) is an hourly short-medium range rainfall forecast of up to 18 hours updated every hour with spatial resolution of about 3 km by 3 km. Six-hourly rainfall forecasts are available for up to seven days ahead. Since basins are hydrologically relevant, the authors perform HRRR skill verification for the years 2016-2019 using conventional verification techniques and mean areal precipitation (basin scale rainfall volume) with respect to multi-radar

multi-sensor (MRMS) QPE (gauge-corrected) rainfall. The authors show that the QPF errors/uncertainties are scale-dependent. The QPF skills show increase as the basin scale and lead time of the forecast increases at short-medium range. In the second part of the study, both QPE and QPFs are forced separately to the hydrologic model called hillslope-link model (HLM) used at the Iowa Flood Center for real-time streamflow forecasting for Iowa. The objective is to understand the contribution of QPF uncertainty structure on the skill of streamflow forecasts. Since real-time streamflow observations (15 minutes resolution) are available at USGS sites, the authors incorporate them using a simple data assimilation framework. Several scenarios of forecasts, such as open-loop combined with QPF, persistence-based approach (using streamflow observations) combined with QPF, and open-loop combined with QPF for more than 18 hours horizon is explored. The authors report the contribution of QPF errors on hydrologic predictions across scales and suggest a forecasting scenario that shows the most enhanced predictability of streamflows.

How to cite: Krajewski, W. and Ghimire, G.: Scale-Dependent Worth of QPF for Real-Time Streamflow Forecasting, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-10958, https://doi.org/10.5194/egusphere-egu2020-10958, 2020.

EGU2020-13671 | Displays | HS1.2.6

Performance of a Physically Based Gap-Filling Technique of in-situ Soil Moisture, in Comparison with Machine Learning

Seulchan Lee, Hyunho Jeon, Jongmin Park, and Minha Choi

As the importance of Soil Moisture (SM) has been recognized in various fields, including agricultural practices, natural hazards, and climate predictions, ground-based SM sensors such as Frequency Domain Reflectometry (FDR), Time Domain Reflectometry (TDR) are being widely used. However, gaps in in-situ SM data are still unavoidable due not only to sensor failure or low voltage supply, but to environmental conditions. Since it is essential to acquire accurate and continuous SM data for its application purpose, the gaps in the data should be handled properly. In this study, we propose a physically based gap-filling method in a mountainous region, in which in-situ SM measurements and flux tower are located. This method is developed only with in-situ SM and precipitation data, by considering variation characteristics of SM: increases rapidly with precipitation and decreases asymptotically afterward. SM data from the past is used to build Look-Up-Tables (LUTs) that contains the amount and speed of increment and decrement of SM, with and without precipitation, respectively. Based on the developed LUTs, the gaps are filled successively from where the gaps started. At the same time, we also introduce a machine learning-based gap-filling framework for the comparison. Ancillary data from the flux tower (e.g. net radiation, relative humidity) was used as input for training, with the same period as in the physically based method. The trained models are then used to fill the gaps. We found that both proposed methods are able to fill the gaps of in-situ SM reasonably, with capabilities to capture the characteristics of SM variation. Results from the comparison indicate that the physically based gap-filling method is very accurate and efficient when there’s limited information, and also suitable to be used for prediction purposes.

How to cite: Lee, S., Jeon, H., Park, J., and Choi, M.: Performance of a Physically Based Gap-Filling Technique of in-situ Soil Moisture, in Comparison with Machine Learning, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-13671, https://doi.org/10.5194/egusphere-egu2020-13671, 2020.

EGU2020-16457 | Displays | HS1.2.6

Channel flow: An underestimated hydrological process?

Samuel Schroers and Erwin Zehe

EGU2020-18200 | Displays | HS1.2.6

Coupled effects of microtopography and time-dependant infiltration capacity on rainfall-runoff-infiltration partitioning on a hillslope

Ebrahim Ahmadinia, Daniel Caviedes-Voullième, and Christoph Hinz

The onset and generation of runoff, and the overall rainfall-runoff transformation, resulting in hillslope and catchment runoff response, are controlled by multiple interacting small-scale processes. Small scale features such as surface microtopography -small variations around the average terrain shape- can govern large scale signatures of runoff dynamics. This is the net result of local heterogeneities in the flow paths and ponding which in turn control the development of the surface water layer and how it connects and flows downslope. It is therefore relevant to understand which microtopographic features may play a governing role in runoff generation dynamics. Given that it is very difficult to assess such processes experimentally in the field, we turn to computational modelling to assess different features, hydrological conditions and the overall response.

 

In this work, we numerically solve a physically-based surface water model (based on the Zero-Intertia approximation of the shallow-water equations) on an idealised hillslope domain, forced by a single pulse of rain. To explore different topographies and microtopographies, we model 1460 surfaces, based on 10 sloping planes (from 0.1% to 10%) on which a sinusoidal microtopography of various amplitudes (from 1 to 10 cm) and wavelengths (from 15 to 200 cm) is overlaid. In a previous proof-of-concept work, we showed how these microtopograhies have an impact on rainfall-runoff-infiltration partitioning and generate different runoff regimes from disconnected flow to steady sheet flow. In this contribution, we extend our analysis to include a more realistic, time-dependent infiltration capacity, and therefore explore the effects this has in the process of ponding and establishing surface flow connectivity. We extend the number of surfaces (within the same ranges) to better observe the different runoff regimes. We quantitatively assess the results mainly in terms of the increase in total infiltration in the presence of microtopography relative to a smooth plane, and qualitatively in terms of the generated runoff regimes.

 

The results show that microtopography increases total infiltration (up to six times in our simulations) over the whole domain relative to a smooth plane and there is a strong non-linear dependency of infiltration and runoff on slope and on the ratio of the characteristic wavelength and amplitude of microtopography. Moreover, three characteristic regimes of influence of microtopography exist: one in which microtopography plays a negligible role, another in which microtopography increases infiltration, but the particular microtopography features are not very relevant, and one regime in which small changes in microtopography generate significant variations on infiltration. Such regimes are the result of the interplay between small (microtopography) and large scale (slope) system features. Finally, the results also show that the time-dependent infiltration capacity can enhance the effect of microtopography on infiltration. From a modelling perspective, these results hint that neglecting microtopography and time-dependent infiltration in hydrological modelling can lead to an underestimation of infiltration and an overestimation of runoff. The coupled analysis of spatial hydrodynamics and hydrological signatures suggests that the latter can be interpreted and explained by the spatiotemporal variations triggered by surface connectivity.

How to cite: Ahmadinia, E., Caviedes-Voullième, D., and Hinz, C.: Coupled effects of microtopography and time-dependant infiltration capacity on rainfall-runoff-infiltration partitioning on a hillslope, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-18200, https://doi.org/10.5194/egusphere-egu2020-18200, 2020.

EGU2020-18951 | Displays | HS1.2.6

Multi scale smoothed particle hydrodynamics using particle agglomeration for simulating rainfall-runoff processes

Manickam Somasundaram, Marlene Gelleszun, and Günter Meon

We present a novel particle based numerical method, which supports regions of particle agglomeration, for simulating water flow in hydrological applications. This is done to tackle the difficulties that arise while modeling due to diverse operation scales, both in space and time. In this study we aim to concentrate only on multiple spatial scales. Smoothed particle hydrodynamics (SPH) is a mesh free method and it enables the interactions of particles in different media, for example media with different porosities. We use a technique of agglomerating particles based on parameters like velocity and treat the agglomerated mass as a single particle. With the presented method, the SPH method can be extended to rainfall-runoff models with multi-phase soil properties. First, the numerical method associated with SPH to solve the shallow water equation (SWE) is introduced. Then the way in which the mass term is replaced during agglomeration is derived. Calculating the modified parameters of a newly agglomerated particle to satisfy the continuity criteria is also introduced and derived. In order to validate the method, benchmark cases that align with our target application with experimental data were chosen from literature study. These include, uniform rainfall falling on an one-dimension flat slope channel, non-uniform rainfall with different duration over an one-dimension flat slope. In order to explore the extent of method a three-dimension test case, where water particles are allowed to pass through a different medium stacked on top of one another with different porosity, is chosen. The three-dimension benchmark case is not inspired from a real time application like the one-dimension test cases, but the results can be scaled and deployed into a flood-forecasting simulation. Also, the proposed method was proven robust and the one-dimension test cases show good agreement with experimental results. The three-dimension test case shows decent improvement in computational time and can provide new possibilities for simulating practical hydrological applications.

How to cite: Somasundaram, M., Gelleszun, M., and Meon, G.: Multi scale smoothed particle hydrodynamics using particle agglomeration for simulating rainfall-runoff processes, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-18951, https://doi.org/10.5194/egusphere-egu2020-18951, 2020.

The results of precision monitoring of the groundwater level are used as the main criterion in study of the mechanism of deformation of a water-saturated reservoir under dynamic impact. The purpose of the field investigation is a registration of the hydrogeological responses to the passage of seismic waves from mining of the iron ore deposit. An instrument-measuring complex of autonomous synchronous registration of seismic signals and hydrogeological responses to mass explosions during underground and surface mining was installed at the site of the iron ore deposit. For the first time, the amplitudes and frequency ranges of the hydrogeological responses of the different aquifers were determined in the near field zone. During mass explosions has been previously established that the reaction of aquifers to explosions is faster than the displacement of soil on the surface. The hydrogeological responses in the water-saturated sands, slates and quartzites are registered at the different frequencies. The change of the reservoir filtration properties under the mass explosions are not possible to judge due to the lack of a long series of observations. Only the continuation of the precise hydrogeological monitoring allows receiving a new data of the deformation of a water-saturated reservoir of pore and pore-fracture types under high-intensity exposure have been obtained. Probably these results can be used for the understanding of the hydrogeological and hydrogeomechanic processes in the near field of earthquakes. The reported study was funded by RFBR according to the research project № 19-05-00809.

How to cite: Gorbunova, E. and Besedina, A.: Study of the hydrogeological responses to mass explosions during mining at the iron ore deposit, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-21353, https://doi.org/10.5194/egusphere-egu2020-21353, 2020.

EGU2020-21737 | Displays | HS1.2.6

Daily streamflow prediction using an LSTM neural network in Alpine catchments

Mohit Anand, Peter Molnar, and Nadav Peleg

Prediction of rainfall-runoff response in Alpine catchments is complex because hydrological processes vary strongly in space and time, they are elevation and temperature dependent, subsurface water stores are heterogeneous, snow plays an important role, and runoff response is fast. As a result, the transformation of rainfall into runoff is highly nonlinear. Machine Learning (ML) methods are suitable for reproducing such nonlinearities between input and output data and have been used for streamflow prediction. Recurrent Neural Networks (RNNs) with memory states, such as Long and Short-Term Memory (LSTM) models, are particularly suitable for hydrological variables that are dependent in time. An example of a recent application of LSTM to the rainfall-runoff transformation in many catchments in the USA showed that the LSTM model can learn physically meaningful catchment embeddings from precipitation-temperature-streamflow data, and performs comparably to widely used conceptual hydrological models (Kratzert et al., 2019).

In this study, we tested the LSTM approach on high-quality daily data from 23 Alpine catchments in Switzerland with three goals in mind. First, the LSTM model was trained and validated using daily climate variables (precipitation, air temperature, sunshine duration) and streamflow data on all catchments individually and the performance was compared to a distributed hydrological model (PREVAH). The performance of the LSTM model was in many (but not in all) cases better than the hydrological model. Second, a single LSTM model was trained in all catchments simultaneously, embedding terrain attributes extracted from the Digital Elevation Model (DEM). In this way differences between catchments related to the elevation and temperature dependent hydrological processes, such as snow accumulation and melt, evapotranspiration, runoff generation, etc., can be captured. We show the performance of this model and evaluate the regionalization potential provided by it. Third, the LSTM model was applied in an ensemble forecasting context, and we discuss the benefits and limitations this application brings compared to forecasting with a process-based hydrological model.

How to cite: Anand, M., Molnar, P., and Peleg, N.: Daily streamflow prediction using an LSTM neural network in Alpine catchments, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-21737, https://doi.org/10.5194/egusphere-egu2020-21737, 2020.

HS2.1.1 – Mountain hydrology under global change: monitoring, modelling and adaptation

EGU2020-13273 | Displays | HS2.1.1

Effects of climate change on runoff variability in mid-latitude montane basins

Jakub Langhammer and Jana Bernsteinová

The study analyzed long-term changes of runoff variability of headwater montane basins in Central Europe as a response to the effects of climate change and modifications to the environment.

The aim was to compare the patterns of variability of the indicators of hydrologic alteration, derived from long-term time series of daily discharge observations in montane basins with the recent premises of climate change effects on surface runoff dynamics in the Central Europe region. In particular, there were tested the following assumptions: (i) recent climate warming will result in the shifts of the runoff seasonality and distribution and in (ii) higher variability of runoff, displayed by a higher frequency of floods and droughts, while (iii) the indicators of runoff balance will remain without significant changes.

These hypotheses were tested in a set of 8 unregulated montane catchments, spreading over the border mountain ranges of the Czech Republic - the Šumava Mountains (Bohemian Forest), Krušné hory (Ore Mountains), Jizera Mountains, Krkonoše (Giant Mountains), Orlické Mountains and Beskydy Mountains. All basins are of comparable size (30-90 km2), and without significant hydrological regulations. Their west-east geographical distribution allows for tracking the potential effects of the gradient of climate continentality in the Central European region. The uninterrupted time series of daily discharge observations from 1953 to 2018 were used for the analyses at the gauging stations. 

We focused on indicators that reflect the aspects of the runoff regime, that are likely to be affected by the assumed effects of the changing climate. Variety of time series analysis and statistical techniques was applied, including the set of 33 Indicators of hydrologic alteration (IHA), 34 Indicators of Environmental flow components, frequency and distribution of the peak an low flows, statistical testing of significance of changes using Mann-Kendall test, breakpoint analysis, analysis of deficit and surplus volumes and homogeneity testing using Buishand, Petitt and SNHT tests.

The study has identified the significant shifts in the hydrological response of montane basins that are apparent in seasonality, balance, and variability of discharge. The analyses proved (i) changes in runoff response reflecting the timing of the observed changes in air temperatures, (ii) the shift of spring snowmelts towards earlier spring and a corresponding decline of may flows, occurring in all of the investigated regions, (iii) diverging trends of high flows across the basins, (iv) changing dynamics of rainfall-runoff response (v) better sensitivity of indicators, reflecting low magnitude events and (vi) decline of low flow indicators across the basins.

How to cite: Langhammer, J. and Bernsteinová, J.: Effects of climate change on runoff variability in mid-latitude montane basins, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-13273, https://doi.org/10.5194/egusphere-egu2020-13273, 2020.

EGU2020-10400 | Displays | HS2.1.1

Analysis of the past and future water resources of the Pyrenees by means of a land-surface simulation

Pere Quintana-Seguí, Anaïs Barella-Ortiz, Omar Cenobio-Cruz, Jean-Philippe Vidal, and Ane Zabaleta

The Pyrenees are the "Water Towers" of several key river basins in France, Andorra and Spain, being the Adour-Garonne and the Ebro the largest ones. The water of these basins is used by agricultural and industrial economic sectors which have a significant socioeconomic impact. Furthermore, the water of these rivers also sustains ecosystems which have an intrinsic value and provide ecosystem services to society. For this reason, an assessment of the past and future evolution of the water resources of the Pyrenees is necessary. Until now, these assessments have often been done at the basin or at the national level, but never the water resources of the Pyrenees were assessed as a whole. This is the main aim of the PIRAGUA project, within which we develop our research.

In order to simulate the continental water cycle of the Pyrenees we have used the SASER (SAFRAN-SURFEX-Eaudyssée-RAPID) modeling chain. SAFRAN is a meteorological analysis system, that allows us to create a gridded dataset of all the variables needed by the SURFEX land-surface model. SURFEX’s outflows (runoff and drainage) are used by Eaudyssée and RAPID to calculate streamflow.

Until now there were two separate implementation of SAFRAN in France (8 km resolution) and Spain (5 km resolution). For this project we have taken the climatic zone level SAFRAN data of both countries and interpolated it to a new common grid at a resolution of 2.5 km. The dataset covers a domain that includes the Adour-Garonne, the Ebro and all other Pyrenean river basins, its time period is 1979/80-2014/15 (which will be extended to 2016/17). The RAPID river routing scheme has been implemented in the simulation domain using HydroSheds to describe the river network.

In order to simulate the future evolution of the continental water cycle we use the Pyrenean climate scenarios developed within the CLIMPY project. These include precipitation and maximum and minimum temperature. SURFEX needs other variables too, such as wind speed, relative humidity and radiation. We solve this problem using an analog based approach similar to Clemins et al (2019).

The simulated streamflow is compared to observed streamflow of natural basins. The results show that 18 (out of 38) non influenced stations present a KGE of daily streamflow larger than 0.5. For monthly streamflow, KGE is larger than 0.5 on 22 stations (out of 38).

The next steps of our research are to quantify the improvement due to the increased resolution (comparing to a lower resolution simulation), calculate trends of relevant variables at the sub-bassin scale and compared them to the observed ones in the past, and analyze future trends of these variables. Finally, we will assess the impacts of these changes on water resources.

This research is funded by the EFA210/16-PIRAGUA project, within the INTERREG V-A España-Francia-Andorra POCTEFA2014-2020 program.

How to cite: Quintana-Seguí, P., Barella-Ortiz, A., Cenobio-Cruz, O., Vidal, J.-P., and Zabaleta, A.: Analysis of the past and future water resources of the Pyrenees by means of a land-surface simulation, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-10400, https://doi.org/10.5194/egusphere-egu2020-10400, 2020.

EGU2020-11287 | Displays | HS2.1.1

Assessing the potential groundwater recharge from precipitation in the Pyrenees in the global change context

Yvan Caballero, Sandra Lanini, Guillaume Hevin, Pierre Le Cointe, Stéphanie Pinson, Jean-François Desprats, Philippe Le Coent, and Benoît Dewandel

The Pyrenees range is a transboundary region shared by Spain, France and Andorre whose water resources are diverse (snowmelt and rainfall runoff in a topographically variable context, groundwater in complex and heterogeneous aquifers) and poorly known. As many other mountain regions, this territory is particularly vulnerable to the impacts of climate change. In the framework of the PIRAGUA project, funded by FEDER through the EU POCTEFA Program, the potential groundwater recharge from precipitation was estimated over the last 30 years at the scale of the Pyrenean range.

 

Using the meteorological forcing data provided at high spatial resolution in the framework of the PIRAGUA Project, the effective rainfall was computed at the daily time step using three different simple water balance methods, including land use effect on evapotranspiration (crop coefficients method) over the 1981-2010 period. Resulting effective precipitation ranges from 50 to more than 2000 mm/year on average and shows strong differences between the east and west sides of the Pyrenean chain.

 

Potential groundwater recharge from precipitation was then estimated using an effective precipitation infiltration ratio derived from the comparison of the IDPR geomorphological index to the baseflow index extracted from selected river discharge time series over the Pyrenees. The resulting potential recharge was finally averaged at the groundwater bodies’ scale of the Pyrenean chain.

 

Corresponding potential groundwater resources were finally compared to groundwater uses estimated at the Pyrenean scale in order to 1) assess their respective importance in relation to water uses and 2) identify the sectors of the territory for which situations of tension on groundwater resources could already be observed, tensions which are likely to increase in the context of climate change.

 

How to cite: Caballero, Y., Lanini, S., Hevin, G., Le Cointe, P., Pinson, S., Desprats, J.-F., Le Coent, P., and Dewandel, B.: Assessing the potential groundwater recharge from precipitation in the Pyrenees in the global change context, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-11287, https://doi.org/10.5194/egusphere-egu2020-11287, 2020.

EGU2020-20231 | Displays | HS2.1.1

Future hydrology of Alpine rivers of Italy: the Interreg project GE.RI.KO Mera

Daniele Bocchiola, Francesca Casale, Leonardo Stucchi, and Giovanni Bombelli

We present preliminary results in fulfilment of the IT-CH Interreg project “GE.RI.KO Mera”. The main aim of the project is to create a common strategy for the management of common water resources, in the transboundary Mera catchment, laid for ¼ in Switzerland, and for ¾ in Italy. Mera river sources in the Maloja mountains of Switzerland, crosses the Bregaglia valley, and reaches Valchiavenna of Italy, then receiving Liro river’s water, and then flows into the Novate-Mezzola lake, and in Como lake soon after.

This area is particularly important, for hydropower production, and large exploitation of water resources for fishing, and leisure in general.

Bregaglia valley carries large sediment load in the river, which affect aquatic species during floods, and lead to progressive filling of hydropower basins, and sediment accumulation along the river, with potential for increased flood risk, and often need for removal. GE.RI.KO project aims to jointly manage the transboundary waters of the Mera river to i) limit alteration of riverbed morphology and erosion, ii) avoid biodiversity loss, and iii) reduce flood risk along the river.

Here we report modelling of hydrology of this high altitude basin with Poli-Hydro model, and an analysis of future climatic conditions in the area of Valchiavenna for different Representative Concentration Pathways (RCP). We use several RCPs from IPCC’s AR5/6, and several GCMs, for a grand total of 21 climate scenarios (plus local downscaling) to force the Poli-Hydro model to depict future hydrological scenarios in the area.

We report main potential hydrological variations, and depict main challenges for water management in the Mera catchment under future scenarios, to be explored by the GE.RI.KO project.

How to cite: Bocchiola, D., Casale, F., Stucchi, L., and Bombelli, G.: Future hydrology of Alpine rivers of Italy: the Interreg project GE.RI.KO Mera, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-20231, https://doi.org/10.5194/egusphere-egu2020-20231, 2020.

EGU2020-18759 | Displays | HS2.1.1

Better understand mountain hydrology to enhance climate change impact assessment

Youen Grusson, Manon Dalibard, Mélanie Raimonet, Sabine Sauvage, Gaël Leroux, Santiago Begueria, Leticia Palazon, and José Miguel Sánchez Pérez

Catchments of European mountains are essential because of their role to provide water to human society. Mountainous area regulate water flux through a complex system of storage and release, playing the role of water tower. Better understand the dynamic functioning of this system at the scale of each compartment and the relationships between the storage and releasing processes are important to understand the impact induced by climate change. In particular, the disappearance of snow during the winter will potentially modify the low flow water level and ecological flow in late spring and early summer, impacting the ecological services provided by e.g. ponds, peat or wetland. The presented study aims to identify the keys factors and their current role in this hydrological system of the Pyrenean Mountains, and identify critical hydrological conditions that will potentially impact the socio-ecological services related to water resources. This goal has been achieved by a development of a high resolution hydrological modeling framework at the scale of the entire Pyrenean massif, together with the study of lower scale representative systems (peatland) and the development of specific future climate scenarios, in order to suggest mitigation actions and adaptability action through water management.

How to cite: Grusson, Y., Dalibard, M., Raimonet, M., Sauvage, S., Leroux, G., Begueria, S., Palazon, L., and Sánchez Pérez, J. M.: Better understand mountain hydrology to enhance climate change impact assessment, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-18759, https://doi.org/10.5194/egusphere-egu2020-18759, 2020.

EGU2020-10370 | Displays | HS2.1.1

Past hydrological trends on the Pyrenees: towards a higher spatial heterogeneity

Ane Zabaleta, David Haro-Monteagudo, Iñaki Antiguedad, and Santiago Beguería

The Pyrenees are a fundamental source of water resources for the territories surrounding this mountain range and beyond, and like other mountainous areas they are very vulnerable under global change. The CLIMPY project (Interreg-POCTEFA) calculated an increase of 1.5 ℃ on average temperature for this region in the last 60 years.

One of the aims of the PIRAGUA project (Interreg-POCTEFA) is to make a regional and temporal characterisation of the water resources of the Pyrenees. To achieve that objective, a common standardized and homogenized database was created for the first time in this transboundary region with streamflow data measured by the different water agencies operating in the area (1956-2015).

To avoid human impacted gauging stations (e.g. upstream reservoirs and large irrigation withdrawals), and to analyse only those with a reasonable quality, only a number of the initially obtained streamflow series were considered. A set of indicators was calculated from the selected daily streamflow series concerning mean, high and low flows at annual and monthly scales for different time periods ending in 2015. 

Results show that median discharge decreased an average of 30% in all gauging stations between 1956 through to 2015. High and low streamflow also decreased during the same period. On average, the number of days below the first quartile increased 10 days per decade, and the number of days above the third quartile decreased 6 days per decade. The interquartile range decreased 4% per decade on average showing that streamflow suffered a generalised reduction between 1956 and 2015. Regarding monthly streamflow, trends for median streamflow and the first quartile are similar to the annual scale. The most significant decrease is observed during spring (12-15% on average), and the lowest decrease occurs in the autumn (6-9% on average). Since 1986, trends change and streamflow increases are observed at some gauging stations with results that are spatially very heterogeneous. This inflection may be an effect of a more spatially heterogeneous climate in the recent past or of land use changes that are not regionally homogeneous, or a combination of both.

How to cite: Zabaleta, A., Haro-Monteagudo, D., Antiguedad, I., and Beguería, S.: Past hydrological trends on the Pyrenees: towards a higher spatial heterogeneity, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-10370, https://doi.org/10.5194/egusphere-egu2020-10370, 2020.

EGU2020-860 | Displays | HS2.1.1

Mapping evapotranspiration of a mountain area using a model without calibration

Davide Gisolo, Ivan Bevilacqua, Maurizio Previati, Davide Canone, Alessio Gentile, Mesmer N'Sassila, and Stefano Ferraris

The mountains are known as the water towers of the World and they are also climate hot spots. Therefore, water availability studies are extremely useful. To this purpose, Evapotranspiration analyses are important because it plays an essential role in water balance. Its estimation is an important challenge in complex terrains because of few measurement sites and of models’ resolution. Research on both meteorological and hydrological models is still ongoing and there are multiple aims: better catch the physical processes in the atmosphere and in the soil and simulate the reaction of ecosystems to temperature changes, droughts and vegetation shifts towards higher altitudes.

It is therefore important to elaborate new tools for the monitoring of mountain environments and ecosystems from a meteo-hydrological and also climatological point of view.

We elaborated and used a high-resolution model to compute the evapotranspiration field of an Alpine domain located in Italy. The model includes a meteorological module and a hydrological module, which is based on a soil bucket approach. The model allowed us to estimate the local water balance and was validated using three eddy covariance quality-controlled data sets. Furthermore, it was also compared to satellite products. The first results indicate a rather good agreement between simulations of our model, observations, and satellite evapotranspiration estimates.

These are first, encouraging results and the model will be hopefully used in a climate change perspective by means of climate models' outputs, to simulate future scenarios in the Alps.

How to cite: Gisolo, D., Bevilacqua, I., Previati, M., Canone, D., Gentile, A., N'Sassila, M., and Ferraris, S.: Mapping evapotranspiration of a mountain area using a model without calibration, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-860, https://doi.org/10.5194/egusphere-egu2020-860, 2020.

The Mediterranean mountains have been subject to significant land abandonment processes during the second half of the 20th century.  The subsequent natural revegetation following abandonment in rural areas has been widely documented to have significant implications on the hydrological cycle and the vegetation dynamics. The Spanish Pyrenees, are one of the most affected areas by these land transformations which could threaten their importance for water supply and agricultural activities in the downstream lowland areas.

Management strategies of these abandoned areas have been debatable during the last decades between scientists, policy-makers and stakeholders. Active Management strategy through shrub clearing is one of the proposed practices that have shown advantages to deal with land abandonment in some regions of Spain. Nevertheless, little is known on the effects of this practice on the hydrological cycle and water resources in abandoned areas. In this study we used the Regional Eco-Hydrological Simulation System RHESSys to estimate shrub clearing effects on water resources in the Aisa valley in the Central Spanish Pyrenees, subject to land abandonment and natural revegetation processes during the past decades. Our results show an increase of annual streamflow and a decrease of annual evapotranspiration following shrub clearing. Nevertheless, the magnitude of these changes may decrease with the age of abandonment and climate change.

How to cite: Khorchani, M., Nadal-Romero, E., and Lasanta, T.: Shrub clearing as Active Management strategy to control land abandonment in the Central Spanish Pyrenees: The effects and the limits, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-1123, https://doi.org/10.5194/egusphere-egu2020-1123, 2020.

As a link between the atmosphere and the earth’s surface, the hydrological cycle is impacted by both climate change and land use/cover change (LUCC). For most basins around the world, the co-variation of climate change and LUCC will continue in the future, which highlights the significance to explore the temporal-spatial distribution and variation mechanism of runoff and to improve our ability in water resources planning and management. Therefore, the purpose of this study is to propose a framework to examine the response of runoff to climate change and LUCC under different future scenarios. Firstly, the future climate scenarios under BCC-CSM1.1 and BNU-ESM are both downscaled and bias-corrected by the Daily bias correction (DBC) method, meanwhile, the future LUCC scenarios are predicted by the Cellular Automaton-Markov (CA-Markov) model according to the integrated basin plans of future land use. Then, based on the baseline scenario S0 (meteorological data from 1966 to 2005 and current situation LUCC2010), the following three scenarios are set with different combinations of future climate land-use situations, i.e., S1: only climate change scenario; S2: only the LUCC scenario; S3: climate and LUCC co-variation scenario. Lastly, the Soil and Water Assessment Tool (SWAT) model is used to simulate the hydrological process and quantify the impacts of climate change and LUCC on the runoff yield. The proposed framework is applied to the Han River basin in China. Results show that: (1) compared with the base period (1966-2005), the annual rainfall, daily maximum, and minimum air temperature during 2021-2060 will have an increase of 4.0%, 1.8℃, 1.6℃ in RCP4.5 while 3.7%, 2.5℃, 2.3℃ in RCP8.5, respectively; (2) from 2010 to 2050, the forest land and construction land in the Han River basin will have an increase of 2.8% and 1.2%, respectively, while that of farmland and grassland will have a decrease of 1.5% and 2.5%, respectively; (3) comparing with the single climate change or LUCC scenario, the co-variation scenario possesses the largest uncertainty in runoff projection. Under the two concentration paths, there is a consistent upward change in future runoff (2021-2060) of the studied basin compared with that in the base period, furthermore, the increase rate in RCP4.5 (+5.10%) is higher than that in RCP8.5 (+2.67%). The results of this study provide a useful reference and help for water resources and land use management in the Han River basin.

How to cite: Tian, J., Guo, S., and Xu, C.-Y.: A framework for quantifying the impacts of future climate and land use/cover changes on runoff in the Han River basin, China , EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-1979, https://doi.org/10.5194/egusphere-egu2020-1979, 2020.

Knowledge of recharge processes in groundwater resource areas is of great importance for developing sustainable water management plans. In an effort to enhance the understanding of recharge in a basalt aquifer, a national water balance soil moisture model was compared with the response in water tables in multiple private pumping bores across the Tamborine Mountain plateau located in South East Queensland, Australia. The water levels in the pumping bores were influenced by the everyday use of the bores, which are utilised for household supply, stock watering, garden watering and irrigation. In each bore, the pumping response was identified and filtered out before being compared to the soil moisture model results. The soil moisture model (AWRA-L Australian Water Resource Assessment Landscape) includes results of surface runoff, soil moisture, evapotranspiration and deep drainage, to a depth of 6 m. The simulated soil moisture levels in the rootzone (rootzone defined as depth between 0 - 1 m), showed a similar hydrographic response following rain events to that observed in water levels in the aquifer. The response in the aquifer compared to the soil moisture showed some of the deeper bores had a lag effect and furthermore, the response also showed dependency on the soil moisture level (%) and on the size/duration of the rain event. It was observed that the simulated deep drainage (recharge) did not correlate to the observed changes in water tables. The soil moisture model simulated a nearly constant deep drainage (recharge) of 0.05±0.01mm a day, whereas the bores showed large increases in water table in response to rainfall events. Previous studies in the area based on the chloride mass balance approach have estimated that the annual deep drainage volume was an average of 30% of annual rainfall, while the soil moisture model approach has simulated an annual deep drainage volume of 1.2 – 1.7% of the total annual rainfall. While these results show that there are shortcomings related to applying the soil moisture model to estimate aquifer recharge, these results are an important initial finding regarding the estimation of recharge in the study area and can be used in water balance calculations for water management purposes. With further research into the observed relationships and parameterisation of these relationships, the soil moisture model could be updated to better represent recharge within this, and similar, study areas.

How to cite: Gurieff, L. B. and Reading, L.: Improving the understanding of recharge in a basalt aquifer based on a soil moisture model, water levels and climatic data, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-2814, https://doi.org/10.5194/egusphere-egu2020-2814, 2020.

EGU2020-3114 | Displays | HS2.1.1

Vilcanota river watershed Hydrology - Peru: Evolution in a changing climate and soil cover.

Danny Saavedra, Pablo Mendoza, and Ximena Vargas

Vilcanota river watershed is located in Cusco region in Peruvian Southeast mountain, on the Atlantic slope. This watershed is important for  cities located within the Cusco region, since it supplies water for human consumption and for agricultural and livestock production. Therefore, it is important to understand the hydrological behavior of the watershed, in order to determine water availability for the past, present and future periods, and to be able to make better decisions.

We analyze  evolution of hydrology in the Vilcanota river watershed, with changing climates and ground cover. To achieve the goal, we propose the use of a flexible modeling platform, such as the unified approach to process-based hydrological modeling called Structure for Unifuing Multiple Modeling Alternatives (SUMMA), which contains a general set of conservation equations, providing flexibility to experiment with different spatial representations, different flux parameterizations, different model parameter values ​​and different time stepping schemes. This modeling platform will allow us to reduce the uncertainty in the structure of hydrological models and thus obtain correct results for the right reasons. The historical data, meteorological forcing, and the streamflow measurement data, taken from the Peruvian National Meteorological and Hydrological Service (SENAMHI) database, is  used to run  the model at a subdaily  level. The performance of the model, is evaluated through objective functions  selected to adequately represent the behavior of the hydrology of the watershed, both at high and low flows. allowing us to obtain good results in hydrology projections during wet and dry periods.

Preliminary results show that in the historical data of the watershed there is a slight trend in the increase in runoff, attributed to the change in ground cover.

How to cite: Saavedra, D., Mendoza, P., and Vargas, X.: Vilcanota river watershed Hydrology - Peru: Evolution in a changing climate and soil cover., EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-3114, https://doi.org/10.5194/egusphere-egu2020-3114, 2020.

EGU2020-5462 | Displays | HS2.1.1

Floods in the Pyrenees region: the PIRAGUA-FLOOD geodatabase

Marina Aznárez-Balta, M. Carmen Llasat, Montserrat Llasat-Botija, Maria Cortès, Joan Gilabert, and Pere Quintana-Seguí

The present contribution shows a spatial and temporal analysis of the flood events in the Pyrenees area for the period 1981-2015. Seven regions from Spain, Andorra and France conform the mountain range: Basque Country, Navarra, Aragon and Catalonia, in Spain; Nouvelle-Aquitaine and Occitanie, in France; and Andorra country. Although some flood databases exist for these countries, usually they only include catastrophic flood events for some regions (i.e. FLOODHYMEX – Llasat et al, 2013- include Catalonia and Languedoc-Roussillon). This contribution shows a new flood geodatabase for the whole Pyrenees mountain chain, developed into the framework of the PIRAGUA project (Interreg POCTEFA EFA210/16). In order to have homogeneous information for all the regions, several data sources have been analysed for this period. The methodology used in the database development, the type of information and the structure of the database, are presented. In order to show the localities affected by floods, different maps of the municipal distribution of flood events have been developed. A flood event is defined as an episode along which one or more surface water floods have been recorded in one or more regions. They are usually produced because of heavy rainfall events. Some statistics on temporal distribution, and an identification of the most important events have been carried out. 182 flood events have been identified for the whole region, classified in catastrophic, extraordinary and ordinary flood events. 41 flood events affected more than one region and 9 of them were catastrophic in at least one. 11% of the events caused a total of 140 casualties in the study period, showing the importance of orography and land-use on the exposure of mountainous areas to flood events, especially in flash flood events. Besides punctual information on maximum rainfall provided by meteorological stations, the rainfall field has been analysed from the SAFRAN reanalysis. Finally, the weather types associated to the flood events have been obtained using the Jenkinson and Collison classification (Jenkinson and Collison, 1977).

 

Jenkinson AF, Collison FP. 1977. An initial climatology of gales over the North Sea. Technical Report, Synoptic climatology Branch Memorandum No. 62, Meteorological Office, Bracknell, UK, 18 pp.

Llasat MC, Llasat-Botija M, Petrucci O, Pasqua AA, Rosselló J, Vinet F, Boissier L. 2013. Towards a database on societal impact of Mediterranean floods within the framework of the HYMEX project. Nat. Hazards Earth Syst. Sci. 13(5): 1337–1350.

How to cite: Aznárez-Balta, M., Llasat, M. C., Llasat-Botija, M., Cortès, M., Gilabert, J., and Quintana-Seguí, P.: Floods in the Pyrenees region: the PIRAGUA-FLOOD geodatabase, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-5462, https://doi.org/10.5194/egusphere-egu2020-5462, 2020.

EGU2020-6642 | Displays | HS2.1.1

Evaluation of precipitation products based on rain gauge data and water budget in a mountainous river basin, Eastern Tibetan Plateau

Yaozhi Jiang, Kun Yang, Xiaodong Li, Wenjiang Zhang, Yan Shen, Yingying Chen, and Xin Li

Precipitation in mountainous areas provides abundant water resources for downstream regions, and reliable precipitation data in these areas is of crucial importance for the management of water resources and water-related disasters. Because in-situ precipitation data are usually scarce in mountainous areas, satellite-based precipitation products are expected to play an important role; however, they should be carefully validated before application. This study evaluated the performance of three high-resolution precipitation products in the mountainous Qingyi River basin, by comparison with both rain gauge-based and water budget-based methods. The basin is located at the eastern margin of the Tibetan Plateau, and has high precipitation leading to high runoff (~1100 mm/year). The three precipitation products are CMPA (the China Merged Precipitation Analysis), IMERG (the Integrated Multi-satellitE Retrievals for GPM) and GSMaP (the Global Satellite Mapping of Precipitation). In general, both rain gauge-based and water budget-based methods showed that CMPA has the highest accuracy and IMERG has the poorest accuracy in this region. In two sub-basins with steep terrain and high precipitation, the rain gauge-based evaluation indicated negative or even positive basin-averaged biases of about 1 mm/day or less, but the water budget analysis indicated that all the products had much larger negative biases, of 2.4 ~ 3.8 mm/day. This difference likely arises because the evaluation based on rain gauge data cannot reflect errors in products at the basin-scale, due to the sparse spatial distribution of rain gauges. Finally, observed altitudinal gradients of precipitation were used to correct the precipitation products. Under this approach the water budget can be better closed but is not always satisfactory. Therefore, developing a high-quality precipitation data set for mountainous regions based only on satellite products and sparse ground observations remains challenging and other data sources (e.g. high-resolution meteorological modeling) should be taken into consideration in future.

How to cite: Jiang, Y., Yang, K., Li, X., Zhang, W., Shen, Y., Chen, Y., and Li, X.: Evaluation of precipitation products based on rain gauge data and water budget in a mountainous river basin, Eastern Tibetan Plateau, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-6642, https://doi.org/10.5194/egusphere-egu2020-6642, 2020.

EGU2020-7634 | Displays | HS2.1.1

High mountain karst aquifer vulnerability to climate change and groundwater transit times

Jorge Jódar, Luis Javier Lambán, Antonio González, Sergio Martos, and Emilio Custodio

Water resources in high mountain karst aquifers are usually characterized by high precipitation than in the surrounding lowlands, with significant recharge and discharge that assure the sustainability of the downstream ecosystems. Consequently, these hydrogeological systems are highly vulnerable to the climate change. The mean transit time (MTT) is a key parameter to describe the behaviour of these hydrologic systems and also to assess their vulnerability.

In high mountain zones, precipitation can be as rainfall and as snowfall. The latter generates snow accumulation that in many cases partially or totally melts in spring and summer, producing small runoffs. In this framework, the karst aquifer recharge show mainly two different mechanisms: (1) diffuse recharge, in which runoff from rainfall and snowmelt enters the epikarst through the whole outcropping area and percolates through low permeability fissured blocks in the way down to the saturated zone, (2) locally concentrated recharge through highly conductive hydrologic features, including different solutional forms (e.g. sinkholes, dolines, etc.), which are generally well-connected to vertical fractures and the drainage network of the aquifer. These recharge mechanisms condition the aquifer response observed at the outlet of the systems at different temporal scales.

This study is conducted in the Paleocene-Eocene karst aquifer of the Ordesa and Monte Perdido National Park (PNOMP) Spain, particularly focussing on the Garcés karst system, whose discharge forms the emblematic Horsetail fall of the National Park. Different karstic forms appear throughout the study zone, including sinkholes, dry and ice caves, dolines and karren fields, thus generating a heterogeneous karstified hydrogeological system.

In this work, the difference on the hydrological response of the fine fissures and the main drainage aquifer network is investigated in terms of the corresponding MTT. To this end, both environmental (d18O and d18H in water) and fluorescent dye (uranine, eosine, amino G acid and naphtionate) tracers are used. The former characterize the MTT associated to the diffuse recharge process by means of the seasonal variation of the isotopic content in both precipitation (dP) and the Garcés spring discharge (dGW). The dye tracers are used to study the hydrogeological organization of the highly conductive drains and to estimate the corresponding MTTs.

The obtained MTT are 1.3 years and 9 days for the environmental and the fluorescent dye tracers, respectively. These values are not very long and point out the difficulties of the aquifer to bear large interannual recharge fluctuations. Additionally, the difference between the estimated MTT values underlines how the heterogeneities of the unsaturated zone may condition both the hydrogeological system response to recharge and the aquifer vulnerability.

 

How to cite: Jódar, J., Lambán, L. J., González, A., Martos, S., and Custodio, E.: High mountain karst aquifer vulnerability to climate change and groundwater transit times, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-7634, https://doi.org/10.5194/egusphere-egu2020-7634, 2020.

EGU2020-10205 | Displays | HS2.1.1

Sustainability of water resources in Andorra under global change: The effects of climate and socio-economic changes in the future of water resources

Cristina Pesado-Pons, Oriol Travesset-Baro, Javier Zabalza, Juan Ignacio López-Moreno, and Marc Pons

Water resources have a fundamental value for both ecosystems and society. However, changes in climate, population, consumption patterns, land use and urbanization are affecting its quality and future availability. In Andorra, a country located in the middle of the Pyrenees, the confluence of climate change and a socioeconomic model with an important weight of tourism industry based on an intensive use of water could threaten the future sustainability of water resources. 

This paper analyses the water resources of Andorra and its future sustainability using the Water Evaluation And Planning system (WEAP) modelling tool. 

The WEAP-Andorra model presents an initial estimate of the national water demand segregated into the main water consumers of the country (tourism, residential, primary sector and power generation). It explores the future evolution of water resources combining climatic and socioeconomic scenarios such as evolution of the population, tourism, power generation plans and land use patterns.

Results of scenarios show that in general terms and at country scale the impact of climate change will not compromise the future water demand. However, in some locations and in specific periods or seasons it could be some challenges to give response to all the demands and rise tensions about what water uses should be prioritized, especially between tourism and ski resort and resident uses.   

The WEAP model presented in this paper is demonstrated a useful tool to support management, decision-making and the design of policies for sustainable water management and adaptation to climate change.

How to cite: Pesado-Pons, C., Travesset-Baro, O., Zabalza, J., López-Moreno, J. I., and Pons, M.: Sustainability of water resources in Andorra under global change: The effects of climate and socio-economic changes in the future of water resources, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-10205, https://doi.org/10.5194/egusphere-egu2020-10205, 2020.

EGU2020-15114 | Displays | HS2.1.1

Evaluation of land cover effects on soil-moisture dynamics: adaptation measures from the territory (Bidasoa catchment, Western Pyrenees).

María Valiente, Ane Zabaleta, Maite Meaurio, Jesus A. Uriarte, and Iñaki Antigüedad

The Pyrenees mountain range is the main source of water resources for a large surrounding region, extending from the Atlantic to the Mediterranean. This area is particularly vulnerable to the consequences of climate change. The PIRAGUA project (Interreg-POCTEFA) evaluates the components of the hydrological cycle in the Pyrenees, with the central objective of improving the adaptation of territories to climate change. One of its tasks focuses on the analysis of the effect that land cover and associated soil properties have on different hydrological services. Indeed, land use and its management directly affect soil hydrology, which is a key factor in streamflow temporal distribution. A better understanding of the water-soil-vegetation system is essential for a reliable hydrological modelling which results should be considered in adaptation strategies to climate change.

To this aim, chemical and physical characterization of soil properties is being conducted at the 681 km2 humid Bidasoa catchment (Pyrenees). In order to understand the soil-moisture dynamics, a monitoring network was established in July 2019 in a 0.4 km2 experimental site within the catchment. Four soil-moisture stations and a meteorological one were installed within the same geological setting, same rainfall conditions and similar soil texture characteristics (silt-loamy texture and about one meter deep), but different land covers (pine forest, oak forest, grassland and fernery). Continuous soil-moisture data obtained to date show that upper soil layers (0-20 cm) are deeply influenced by top vegetation cover. Grassland has the highest soil-moisture variations, ranging from 16.2 to 36.6 %, as they closely mirror precipitation patterns. Pine and oak forests present similar variation trend, varying from 33.9 to 42.8 % and from 35.3 to 41.9 %, respectively. Soil-moisture at fernery goes from 30.5 to 36 %. Minimum soil-moisture values coincide in all plots with the end of the dry period (end of September). Maximum values, occurring during very heavy and continuous precipitation in November (647 mm registered from 1 to 24 November), are considered as a proxy for saturated soil conditions. In all the plots, fluctuations in soil-moisture diminish significantly with increasing soil depth. However, considerable differences are found in the vertical soil-moisture profile across land covers. In both forest plots, a decreasing trend of soil-moisture within the profile is observed, while grassland and fernery show an increasing trend. Preliminary results show that soil water infiltration is different among different land covers, which give some insight into the hydrological functionality of soil under different vegetation types. Longer records of soil-moisture dynamics in the area would contribute to better assess the linkages between water, soil and vegetation and, in turn, to improve hydrological modelling in humid mountainous areas. This knowledge is necessary for a better consideration of the adaptation measures that should be taken from the territory.

How to cite: Valiente, M., Zabaleta, A., Meaurio, M., Uriarte, J. A., and Antigüedad, I.: Evaluation of land cover effects on soil-moisture dynamics: adaptation measures from the territory (Bidasoa catchment, Western Pyrenees)., EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-15114, https://doi.org/10.5194/egusphere-egu2020-15114, 2020.

Glaciers in the tropical Andes play an important role for both water supply, economic activities and cultural beliefs. Their importance is particularly high during the dry season (May – September) when glaciers can contribute more than 50% to total streamflow. People are used to take advantage of the important buffering function of the glaciers, but in a climate change context with rapid glacier retreat, this dependence could poses a considerable risk.

Several studies have focused on understanding and simulating the glacio-hydrological patterns for historical and future periods by using different hydrological models with different levels of complexity. However, most existing studies focus on regions with high availability of data, while data scarce regions are studied poorly.

The Vilcanota basin is located in such a data scarce region and encompasses the second largest glaciated mountain range in Peru and the tropics worldwide. As in many other mountainous regions, high-mountain conditions with complex topography and related variations of climatic variables are contrasted with poor availability of data. In view of this challenge, a key question is what level of model complexity would be most appropriate to achieve robust simulations of the hydrological cycle for historical and future climate conditions?

To answer this question, we simulated the hydrological conditions in the Sibinacocha catchment (area: 132 km2; glacier extent: 15 km2) that is part of the upper Vilcanota basin. The simulation was performed with three different hydrological models of different complexity on a monthly time scale from 1981 to 1996. Input data like precipitation and temperature were obtained from the Peruvian gridded precipitation and temperature data set PISCO2.1 (SENAMHI). Streamflow records for calibration were obtained from a hydropower company in the area. Finally, glacier outlines were obtained for three different periods from satellite images in order to incorporate glacier change.

The selected models include a lumped hydrological model based on equations by Temez (6-parameters), and two implementations of the HBV model (HBV Light and RS Minverve with 15 and 14 parameters respectively). Each model is capable of simulating groundwater and glacier contribution. For the simulations with HBV, the catchment was divided into 10 elevation bands. For the simulation with RS Minerve an additional Glacier and Snow model was performed with its own pool of parameters (10-parameters) and own elevation bands. Calibration was performed in two ways: 1) comparing observed and simulated flows, and 2) comparing the simulated and expected glacier and snow contribution to streamflow.

Results show that each of the models examined can reach high efficiencies when using only streamflow records for calibration. By contrast, multicriteria calibration provides more robust results than using one single indicator, even when efficiency indicators are in the same range of values.

In the context of the study region, we found that increasing complexity for hydrological simulation is only feasible if adequate input data are available. In cases with scarce data, lumped or simple semi-distributed models provide robust results. These simulations can be used later to implement more complex models and tools.

How to cite: Munoz, R., Huggel, C., and Viviroli, D.: Comparing simple and complex hydrological models in regions with scarce data: a case study in the upper Vilcanota basin, Peru, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-19829, https://doi.org/10.5194/egusphere-egu2020-19829, 2020.

Predictions in ungauged basins still present one of the major challenges in hydrology. In many cases, the absence of a stream gauge also implies a low density of the meteorological monitoring network in these catchments and surroundings as well as little available data on water management infrastructure and agricultural consumptions. This combination creates a circle of uncertainties and thus individual influences of relevant water balance components are difficult to disentangle and quantify. 

The original Budyko curve presents a very general model that yields, to first order, an estimate of the steady-state water balance of a catchment at the climatological scale, assuming its landscape and functioning has evolved naturally and free of anthropogenic interferences. Even at smaller time scales, the Budyko relationship allows approximating the water partitioning in the catchment, and thus helps correct erroneous assumptions[JW1]  or missing information about for instance unknown human-induced alterations. On the other hand, an increasing variety of global remote-sensing data products is becoming available providing spatial estimates of land surface properties such as for instance vegetation indexes or soil moisture. Even if the predictive power of such products in terms of absolute values remains questionable, it is possible to derive coarse spatial patterns or temporal dynamics to narrow down zones and orders of magnitude of interferences with the natural hydrological cycle such as reservoirs or irrigated lands. This study combines these two general approaches in order to improve hydrological modelling and system understanding of the semi-arid Lurín catchment in the Western Andes of Peru.

How to cite: Bondy, J., Zehe, E., and Wienhöfer, J.: Can the Budyko framework and satellite data help improve hydrological modeling in ungauged and poorly monitored catchments? The case study of the Lurín catchment in Peru, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-20284, https://doi.org/10.5194/egusphere-egu2020-20284, 2020.

The Xinjiang Uyghur Autonomous Region is the area on Earth which is most remote from any ocean and the annual precipitation is only 50 mm. Water availability for e.g. agriculture, water supply, and hydropower production is limited in this area. The area has ~20 000 glaciers and they are the main source for water resources. However, since the 1950s, the glaciers are continuously retreating by 20-30%, and result reductions runoff in the lower reaches of some rivers. In this study, we use a widely used hydrological model (HBV) with a glacier retreat module to study the impacts of climate change and glacier retreat on water resources. An ensemble of climate projections up to the end of the century will be explored and the WEAP (Water Evaluation And Planning) model system will be used to analyze impacts on the society.

How to cite: Li, H.: Impacts of climate change and glacier retreat on water resources and society in the Xinjiang Uyghur Autonomous Region, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-21862, https://doi.org/10.5194/egusphere-egu2020-21862, 2020.

Runoff decrease as was triggered or exacerbated by human activities over the past decades on the Loess Plateau has grown to be a hot spot increasingly drawing nationwide concerns; distinguishing human-induced runoff-altering factors from one another is of great significance to decision-making on maintaining regional water, ecological and economic security. Sediment-trapping dams (STDs) construction and revegetation are the two major soil conservation practices regarded to have also caused runoff reduction, whose hydrologic effects on the basin scale have not been separated quantitatively. Our study, choosing the Huangfuchuan River Basin as the study area and based on analyses of its hydrologic, climatic and underlying condition changes, proposed a physically-based attribution framework which is able to account for the hydrological effects of STDs, revegetation, land use change and climate change simultaneously, and attributed runoff decrease of the basin among factors including climate change, STDs construction, revegetation and land use cover change. The model-based attribution results indicate that STDs construction caused a 45% (48%) runoff reduction from 1976-1988 to 1989-2000 (2001-2014) and revegetation was responsible for a 30% runoff decrease from 1976-1988 to 2001-2014, with daily simulation implying that the hydrologic effect of revegetation to affect flow magnitudes more consistently than that of STDs. Our study demonstrates that STDs construction is the prime contributor to runoff decrease in the study area and suggests that STDs should be taken into account in similar studies on the Loess Plateau in the future.

How to cite: Lu, B., Lei, H., Yang, D., and Fu, X.: Separating the effects of revegetation and sediment-trapping dams construction on runoff decrease in a semi-arid watershed of the Loess Plateau, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-21130, https://doi.org/10.5194/egusphere-egu2020-21130, 2020.

EGU2020-20379 | Displays | HS2.1.1

Small but essential in hydrogeochemical cycles: headwater mountain catchments

Gaël Le Roux, Marilen Haver, Thomas Rosset, Dirk Schmeller, Laure Gandois, Deonie Allen, Stéphane Binet, Anaelle Simonneau, Youen Grusson, Thierry Camboulives, Sabine Sauvage, Didier Galop, Simon Gascoin, and José Miguel Sánchez Pérez

Despite their small size, headwater catchments of European mountains are essential because they provide many ecosystem services (water quality, energy, tourism, ecological niches).

Based on the hydrological monitoring of a mountain catchment in the central Pyrenees and the extreme conditions encountered in the past and expected in the future, we present scenarios for the evolution of hydrological regimes that will potentially impact the socio-ecological services by high mountain mires, ponds and lakes. In particular, in view of the exacerbated climate change in the high mountains, the shortening of snow season will potentially impact the ecosystem services by the ponds, modifying the minimum water level and/or ecological flow in late spring and early summer. For example, these ponds play an essential role as ecological refuges compared to larger lakes, which are subject to invasions by non-native organisms. Peat pools also play an essential role in the cycling of chemical elements, including carbon. Their modification, their increased intermittency due to more frequent and intense climatic variability will deeply modify, for example, the export of dissolved organic carbon from peatlands.

While it is difficult to accurately predict the future of mountain watersheds, our study aims to identify the key factors for their current roles in biodiversity, water sustainability and in ecological services as well as to determine their future adaptability to other human pressures such as mini-hydroelectric power plants.

How to cite: Le Roux, G., Haver, M., Rosset, T., Schmeller, D., Gandois, L., Allen, D., Binet, S., Simonneau, A., Grusson, Y., Camboulives, T., Sauvage, S., Galop, D., Gascoin, S., and Sánchez Pérez, J. M.: Small but essential in hydrogeochemical cycles: headwater mountain catchments, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-20379, https://doi.org/10.5194/egusphere-egu2020-20379, 2020.

EGU2020-11623 | Displays | HS2.1.1

Evaluating water balance components for forested headwater catchment undergoing environmental changes

Veronika Mikesova, Michal Dohnal, Jana Votrubova, and Tomas Vogel

Evaluating seasonal and long-term variations in water balance at catchment scale can be useful for assessing the current status and trends in water resources availability. Components of water balance reflect meteorological and climate variability, and vegetation cover development.

The experimental catchment Uhlířská is a small forested headwater catchment in the Jizera Mountains, Czech Republic. The catchment was extensively deforested in the 80´s. Damaged trees long exposed to the effects of air pollutants were poorly resistant to wind and pests. In the 90´s, new spruce forest was planted. The catchment has been subject to long-term monitoring. The 19-year series of data including air temperature, rain and snow precipitation, discharge, groundwater levels, wind velocity, and air humidity, is examined.

Our study provides basic analysis of directly measured components of water balance (precipitation and discharge, annual and seasonal runoff coefficients). The study further deals with the evaluation of the unmeasured components of the water balance (evapotranspiration and water storage). An interception model was employed to calculate the interception loss. Potential evaporation and transpiration during vegetation seasons were estimated by Penman and Penman-Monteith methods. Snow sublimation was estimated in the winter seasons. Effect of the forest development during the period of interest was considered.

The catchment water balance equation suggests significant changes of the water storage over the observation period, implying its decrease in recent years. However, baseflow and deep water storage seem to be unchanged. This discrepancy could be partly attributed to the decrease in shallow water storage and/or more pronounced transpiration reduction in recent vegetation seasons.

The research is supported by the Czech Science Foundation Project No. 20-00788S.

How to cite: Mikesova, V., Dohnal, M., Votrubova, J., and Vogel, T.: Evaluating water balance components for forested headwater catchment undergoing environmental changes, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-11623, https://doi.org/10.5194/egusphere-egu2020-11623, 2020.

HS2.1.2 – Snow and ice accumulation, melt, and runoff generation in catchment hydrology: monitoring and modelling

EGU2020-4863 | Displays | HS2.1.2 | Highlight

Regional pattern of annual snow cover duration in the Greater Alpine Region (2000 – 2018)

Markus Hrachowitz, Stefan Fugger, and Karsten Schulz

This study analyses regional differences in annual snow cover duration as quantified by the annual number of days with snow cover (Dsc) and investigates differences in sensitivity of Dsc to climatic variability across the Greater Alpine Region over the 2000-2018 period. MODIS snow cover data were used to estimate Dsc based on the Regional Snowline Elevation (RSLE) method, a spatial filter technique for large-scale cloud cover reduction.

Dsc over the study period closely follows the relief, with a mean Dsc of ~10–60 days at elevations of 500 m that increase to about 100–150 days at 1500m. South of the main alpine ridge, Dsc is, at the same elevation, consistently lower than north of it with differences of ΔDsc  ~25–50 days. Similarly, the eastern part of the study region experiences longer snow cover duration than the western part. This difference is particularly pronounced at elevations below 1500m where ΔDsc ~25 days. Throughout the study period, a general upward shift of the RSLE was observed for most parts of the Greater Alpine Region. This upward shift, characterized by later onset of snow accumulation (∆Dstart ~14–30 d) and earlier melt-out at the end of the snow season (∆Dend ~10–20 d), translates into reductions of the annual number of snow-covered days by up to ΔDsc = -46 days over the study period. The data suggest that, in particular, low-elevation  (< 600m.a.s.l.) regions in the north-eastern part of the Greater Alpine Region, as well as elevations between 1400 and 2000 m in the north-western part of the study region experienced the most pronounced reductions of Dsc., whereas ΔDsc remained very limited south of the main Alpine ridge. The spatially integrated MODIS-derived estimates of Dsc correspond well with Dsc estimates derived from longer-term point-scale observations at >500 ground station observations across the region. In the majority of regions, the temporal evolution of Dsc over the 2000-2018 study period also reflects the longer-term Dsc trends as estimated from these point-scale observations (1970-2014). This provides supporting evidence that the widespread decline of Dsc across the Greater Alpine Region as estimated based on MODIS data is largely not caused by isolated short-term climatic variability but coincides with multi-decadal fluctuations. A comparison of the sensitivities of Dsc to climatic variability indicates that neither mean winter temperatures Tw nor annual solid precipitation totals Ps, are consistent first order controls on Dsc across  elevations and regions. Rather, the data highlight the importance of the interaction between the two variables: depending on the respective sensitivities of Dsc to changes in either variable, Tw or Ps, respectively, the interplay between them can reinforce or largely off-set potential effects on Dsc in different regions in the Greater Alpine Region. The regional differences in ΔDsc with a less pronounced decline south of the main Alpine ridge are largely a consequence of this interplay: while Tw evolved similarly North and South of the Alpine ridge, many southern regions, unlike the northern regions, experienced an increase in Ps that offsets the effects of positive temperature trends.

How to cite: Hrachowitz, M., Fugger, S., and Schulz, K.: Regional pattern of annual snow cover duration in the Greater Alpine Region (2000 – 2018), EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-4863, https://doi.org/10.5194/egusphere-egu2020-4863, 2020.

Previous investigations have reported that the performance of the traditional snow cover mapping algorithms based on the Normalized Difference Snow Index (NDSI), derived from a multispectral optical airborne/spaceborne sensor, significantly degrades on transitioning from non-forested to forested landscapes. The thick canopy cover in forested landscapes obscures both the upwelling and the downwelling radiance and hence impairs the detection of the underlying snow cover on the forest floor via NDSI thresholding due to the shift in the apparent threshold. Although NDSI has been reported to be an ineffective index for extracting snow information from forested areas, this investigation presents contrary views. A novel perspective is introduced on exploiting the temporal NDSI-NDVI statistics for extracting snow information under the canopy, as has been also reported important in the past literature when considered together, to reconstruct the actual snow cover scenario over the mixed landscape, comprising both forested areas of varying densities and open vegetation-free patches. The Black Forest (Schwarzwald) is a large forested mountainous terrain at about 200-1500 m above sea level situated in the Federal State of Baden-Württemberg in the southwest corner of Germany. The region is bounded by the Rhine river valley to the west and south stretching in an oblong manner with a length of about 160 km and breadth of up to 50 km. The Black Forest consists of approximately 80% coniferous (spruce, fir, and pine) and 20% deciduous (beech, birch, and oak), with about 70% of the region under forest cover. Seasonal snowmelt water and natural springs originating in this region sources major European rivers like the Danube and the tributaries of the Rhein like the Murg and the Neckar. Therefore, it is essential to monitor snow accumulation under the canopy to accurately forecast and investigate the influence of the snowmelt runoff in such major catchments. One of the test sites is situated in the Murg catchment at Hundseck near the town of Baden-Baden at the north-western border of the Black Forest mountain range. This investigation employs Sentinel-2 multispectral optical data from the previous season in order to test the proposed approach. The proposed method is tested with the European Space Agency's open-access Sentinel-2 multispectral optical satellite data, over the Hundseck test site in the Black Forest. The snow extent map is validated with the Normalized Difference Forest Snow Index (NDFSI), which was proposed as an alternative for NDSI to map the canopy underlying snow in evergreen forests. The proposed algorithm is simple and computationally frugal. Temporal NDSI-NDVI statistics in conjunction with mathematical morphological operation has resulted in significant improvement in the detection of under canopy snow cover. It is noteworthy that the performance of the algorithm inherently shows a dependence on the forest LAI. An improvement of more than 50% is achieved in the under-canopy snow cover mapping. A priori knowledge regarding the LAI of forests will enable adaptive tuning of the algorithm locally for better performance under dense canopy conditions.

How to cite: Muhuri, A.: A Novel Perspective on Mapping Snow Cover Under Forest Canopy With Sentinel-2 Multispectral Optical Satellite Sensor Over Black Forest Germany, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-5617, https://doi.org/10.5194/egusphere-egu2020-5617, 2020.

EGU2020-14513 | Displays | HS2.1.2

Estimating snow line elevation using publicly available webcam images and Sentinel-2 snow cover maps

Céline Portenier, Martina Hasler, Simon Gascoin, and Stefan Wunderle

Publicly available webcam images offer an enormous potential to study the variability of snow cover on a high spatio-temporal scale. Such cameras allow detailed analyses of snow cover on steep slopes due to their oblique view on the mountains and can provide snow cover information even under cloudy weather conditions. Our webcam-based snow cover monitoring network comprises several hundreds of webcams and enables to gather snow cover information over a large area with a minimum amount of manual user input. This information can serve as a reference for improved validation of satellite-based approaches, as well as complement satellite-based snow cover retrieval, in particular under cloudy weather conditions. Here, we present a framework to estimate the regional snow line elevation in the Swiss Alps. The snow line elevation is an important indicator of snow cover in mountainous regions and can be used, for example, as an input for hydrological modeling or to study the seasonality of river discharge. We compare and combine snow line retrieval from Sentinel-2 snow cover maps and webcam-based snow cover information to analyze regional differences in the spring snowmelt period. Since cloud cover is an important factor that affects the quality of satellite-based snow cover products, the combination with snow information from webcams can improve the accuracy and can fill temporal gaps, especially during recurrent cloud cover. Furthermore, we present a method to detect cloud cover in webcam images and discuss limitations of webcam-based snow cover monitoring.

How to cite: Portenier, C., Hasler, M., Gascoin, S., and Wunderle, S.: Estimating snow line elevation using publicly available webcam images and Sentinel-2 snow cover maps, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-14513, https://doi.org/10.5194/egusphere-egu2020-14513, 2020.

The current study started by examining the three most established snow indices, namely the NDSI (normalized difference snow index), S3, and NDSII-1 (normalized difference snow and ice index), based on their capabilities to differentiate snow pixels from cloud, debris, vegetation, and water pixels. Furthermore, considering the limitations of these indices, a new spectral index called the snow water index (SWI) is proposed. SWI uses spectral characteristics of the visible, SWIR (shortwave infrared), and NIR (near infrared) bands to achieve significant contrast between snow/ice pixels and other pixels including water bodies. A three-step accuracy assessment technique established the dominance of SWI over NDSI, S3, and NDSII-1. In the first step, image thresholding using standard value (>0), individual index theory (fixed threshold), histogram, and GCPs (ground control points) derived threshold were used to assess the performance of the selected indices. In the second step, comparisons of the spectral separation of features in the individual band were made from the field spectral observations collected using a spectroradiometer. In the third step, GCPs collected using field surveys were used to derive the user’s accuracy, producer’s accuracy, overall accuracy, and kappa coefficient for each index. The SWI threshold varied between 0.21 to 0.25 in all of the selected observations from both ablation and accumulation time. Spectral separability plots justify the SWI’s capability of extraction and removal of the most critical water pixels in integration with other impure classes from snow/ice pixels. GCP enabled accuracy assessment resulted in a maximum overall accuracy (0.93) and kappa statistics (0.947) value for the SWI. Thus, the results of the accuracy assessment justified the supremacy of the SWI over other indices. The study revealed that SWI demonstrates a considerably higher correlation with actual snow/ice cover and is prominent for spatio-temporal snow cover studies globally.

How to cite: Dixit, A. and Goswami, A.: Development and Evaluation of a New “Snow Water Index (SWI)” for Accurate Snow Cover Delineation, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-10724, https://doi.org/10.5194/egusphere-egu2020-10724, 2020.

EGU2020-11904 | Displays | HS2.1.2

Towards a Pan-European snow cover and melt extent product from Sentinel-1 SAR and Sentinel-3 SLSTR Data

Thomas Nagler, Lars Keuris, Helmut Rott, Gabriele Schwaizer, David Small, Eirik Malnes, Kari Luojus, Sari Metsaemaeki, and Simon Pinnock

The synergistic use of data from different satellites of the Sentinel series offers excellent capabilities for generating high quality products on key parameters of the global climate system and environment. A main parameter for climate monitoring, hydrology and water management is the seasonal snow cover. In the frame of the ESA project SEOM S1-4-SCI Snow, led by ENVEO, we developed, implemented and tested a novel approach for mapping the total extent and melting areas of the seasonal snow cover by synergistically exploiting Sentinel-1 SAR and Sentinel-3 SLSTR data and apply these tools for snow monitoring over the Pan-European domain.

Whereas data of medium resolution optical sensors are used for mapping the total snow extent, data of the Copernicus Sentinel-1 mission in Interferometric Wide Swath (IW) mode at co- and cross-polarizations are used for mapping the extent of snowmelt areas applying change detection algorithms. In order to select an optimum procedure for retrieval of snowmelt area, we conducted round-robin experiments for various algorithms over different snow environments, including high mountain areas in the Alps and in Scandinavia, as well as lowland areas in Central Europe covered by grassland, agricultural plots, and forests. In mountain areas the tests show good agreement between snow extent products during the melting period derived from SAR data and from Sentinel-2 and Landsat-8 data. In lowlands ambiguities may arise from temporal changes in backscatter related to soil moisture and agricultural activities. Dense forest cover is a major obstacle for snow detection by SAR because the surface is masked by the canopy layer which is a major scattering source at C-band. Therefore, areas with dense forest cover are masked out. Based on this results we selected for the retrieval of snowmelt area a change-detection algorithm using dual-polarized backscatter data of S1 IW acquisitions. The algorithm applies multi-channel speckle filtering and data fusion procedures for exploiting VV- and VH-polarized multi-temporal ratio images. The binary SAR snowmelt extent product at 100 m grid size is combined with the Sentinel-3 SLSTR and MODIS snow products in order to obtain combined maps of total snow area and melting snow. The optical satellite images provide information on snow extent irrespective of melting state but are impaired by cloud cover. For generating a fractional snow extent product from MODIS and Sentinel-3 SLSTR data we apply multi-spectral algorithms for cloud screening, the discrimination of snow free and snow covered regions and the retrieval of fractional snow extent. In order to fill gaps in the optical snow extent time sequence due to cloud cover we apply a data assimilation procedure using a snow pack model driven by numerical meteorological data of ECMWF, simulating daily changes in the snow extent. We present the results of the Pan-European snow cover and melt extent product derived from optical and SAR data. The performance of this product is evaluated in different environments using independent validation data sets including in-situ snow and meteorological measurements, snow products from Sentinel-2 and Landsat images, as well as high resolution numerical meteorological data.

How to cite: Nagler, T., Keuris, L., Rott, H., Schwaizer, G., Small, D., Malnes, E., Luojus, K., Metsaemaeki, S., and Pinnock, S.: Towards a Pan-European snow cover and melt extent product from Sentinel-1 SAR and Sentinel-3 SLSTR Data, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-11904, https://doi.org/10.5194/egusphere-egu2020-11904, 2020.

Mountain areas have raised a lot of attention in the past years, as they are considered sentinel of climate changes. Quantification of snow cover changes and related phenology in global mountain areas can have multiple implications on water resources, ecosystem services, tourism, and energy production [1]. Up to now, several studies have investigated snow cover changes at continental scale and there are several indications of snow cover decline over the Northern Hemisphere [2, 3], despite no study has analyzed snow behavior specifically in mountain areas at global level. In this context, this study investigates the changes in the main snow cover parameters (snow cover area, snow cover duration, snow onset and snow melt) over global mountain areas from 2000 to 2018.

To proper monitor the evolution of snow changes at global mountain areas and interlinkages with meteorological drivers (air temperature, snowfall), automatic procedures were developed based on MODIS imagery in global mountain areas over the period 2000-2018 by exploiting Google Earth Engine where the whole time series of MODIS is available at a global scale. MODIS snow cover products have the highest resolution available, 500 m, and with daily global acquisitions. From MODIS snow cover areas (MOD10v6), snow phenology parameters were derived, namely snow cover duration, snow onset and snow melt. Together with snow cover and phenology changes, snow albedo changes were assessed, especially in relation to snow onset and melt variability.

The results of the trend analysis carried with Man-Kendall statistics indicate that around 78% of the global mountain areas present a snow decline. In average, snow cover duration has decreased up to 43 days, and a snow cover area up to 13%. Significant snow cover duration changes can be linked in 58% of the areas to both delayed snow onset, and advanced melt. Few areas show positive changes, mainly during winter time and located in the Northern Hemisphere.

Considering the relationship with meteorological parameters and albedo, air temperature is detected as the main driver for snow onset and melt, while a mixed effect of air temperature and precipitation dominates the winter season. Moreover, snowmelt timing is strongly related to significant changes in snow albedo during March and April in the Northern Hemisphere. Regarding snow onset changes, it has been detected a latitude amplification for the dependency con air temperature, indicating that the sensitivity of snow onset on temperature changes is amplified going from higher to lower latitude.

 

References

[1] Barnett, T.P., Adam J.C., Lettenmaier D.P. Potential impact of a warming climate on water availability in snow-dominated regions, Nature 438 (2005).

[2] Bormann, K. J., Brown, R. D., Derksen, C., Painter, T. H. Estimating snow-cover trends from space, Nat. Clim. Change 8, 924–928 (2018).

[3] Ye. K. H., & Wu, R. G. Autumn snow cover variability over northern Eurasia and roles of atmospheric circulation. Adv. Atmos. Sci. 34(7), 847–858 (2017) doi: 10.1007/s00376-017-6287-z.

How to cite: Notarnicola, C.: How is snow cover in global mountain area changing? Detection of snow cover and snow phenology changes by using MODIS imagery over 2000 - 2018, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-20482, https://doi.org/10.5194/egusphere-egu2020-20482, 2020.

EGU2020-7530 | Displays | HS2.1.2

Evaluation the MOD10A1 daily snow albedo product (v. 6) on Livingston Island, Antarctica

Alejandro Corbea-Pérez, Javier Fernández-Calleja, Carmen Recondo, and Susana Fernández

One of the factors that can most influence climate changes on a global scale is the albedo decrease, associated with a temperature increase and a snow cover decrease, mainly in the polar areas, where the remote sensing data are essential because there is much difficulty access to obtain measurements in situ. Therefore, evaluations of satellite measurements are essential.

The daily MOD10A1 snow product provides daily measurements of albedo. Version 6 is currently available. In Antarctica, and more specifically on Livingston Island (South Shetland Archipelago), where one of the Spanish Antarctic bases is located, the daily snow albedo product of MODIS (MOD10A1) has been evaluated using version 5 data (Calleja et al. 2019). However, several authors have recommended updating the analyses based on version 6 data (Box et al. 2012, Casey et al. 2017), as they are more accurate.

In this work, we have analyzed the albedo behavior using MOD10A1 version 6 data between 2006 and 2015 and we have seen an increasing trend of albedo. Version 5 showed an increase of 0.07 per decade. However, version 6 data show less variability (0.04 per decade), and its results are closer to those obtained in the measurements in situ (0.03 per decade). In addition, the results obtained allow us to affirm that the MOD10A1 daily albedo product (v. 6) can be used to determine the albedo in the study area.

References:

Box, J. E., Fettweis, X., Stroeve, J. C., Tedesco, M., Hall, D. K., & Steffen, K. (2012). Greenland ice sheet albedo feedback: thermodynamics and atmospheric drivers. The Cryosphere, 6(4), 821-839.

Calleja, J. F., Corbea-Pérez, A., Fernández, S., Recondo, C., Peón, J., & de Pablo, M. Á. (2019). Snow Albedo Seasonality and Trend from MODIS Sensor and Ground Data at Johnsons Glacier, Livingston Island, Maritime Antarctica. Sensors, 19(16), 3569.

Casey, K. A., Polashenski, C. M., Chen, J., & Tedesco, M. (2017). Impact of MODIS sensor calibration updates on Greenland Ice Sheet surface reflectance and albedo trends. The Cryosphere, 11(4), 1781-1795.

How to cite: Corbea-Pérez, A., Fernández-Calleja, J., Recondo, C., and Fernández, S.: Evaluation the MOD10A1 daily snow albedo product (v. 6) on Livingston Island, Antarctica, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-7530, https://doi.org/10.5194/egusphere-egu2020-7530, 2020.

EGU2020-10165 * | Displays | HS2.1.2 | Highlight

What happens when the ice is gone? A hydrological journey into the glacier forefield subsurface

Tom Müller, Bettina Schaefli, and Stuart N. Lane

Rapid glacier recession related to recent climate change in Alpine regions is exposing large areas of previously ice-covered till and bedrock. These newly created proglacial areas are composed of poorly sorted sediments and debris of mixed subglacial (till), englacial and supraglacial origin. They are subject to rapid geomorphological and ecological modifications. They also constitute potential new groundwater reservoirs for rain, snowmelt and ice melt. The hydrology of such glaciated catchments is therefore evolving, but the connectivity between glacier meltwater and other paraglacial structures such as talus slopes, outwash plains or small lakes to these areas remains unclear. We propose a conceptual model of water connectivity and storage based on the Otemma glacier, one of the largest Swiss glaciers, which summarizes the key geomorphological structures and their hydrological functions. In particular, we combine multiple field data such as water table fluctuations, river discharge, isotopic analysis and geophysical studies from the proglacial area of the Otemma glacier to show the growing importance of the outwash plain for storing water and maintaining baseflow in these headwater catchments. We show that the accumulation of reworked subglacial till and exported sediments from the glacier create new reservoirs for the storage and release of water which may become larger in regions where the subglacial bedrock has a low slope and where ice is rapidly retreating. These fluvioglacial aquifers are mainly recharged by ice-melt at present but could store more snowmelt and precipitation in the future. The processes influencing sediment export and aggradation combined with future snow and ice melt dynamics are therefore key to understanding the future hydrological functioning of these catchments. River and groundwater dynamics will eventually shape the biodiversity and vegetation succession of these areas that are hotspots for many endemic species and where soil stabilization and development will create a clear feedback on the future sediment and water budget of high Alpine environments.

How to cite: Müller, T., Schaefli, B., and Lane, S. N.: What happens when the ice is gone? A hydrological journey into the glacier forefield subsurface, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-10165, https://doi.org/10.5194/egusphere-egu2020-10165, 2020.

EGU2020-9690 | Displays | HS2.1.2

Understanding monsoon controls on the energy- and mass-balance of glaciers in High Mountain Asia

Stefan Fugger, Evan Miles, Michael McCarthy, Catriona Fyffe, Marin Kneib, Simone Fatichi, Wei Yang, and Francesca Pellicciotti

The Indian Summer Monsoon (ISM) shapes the melt and accumulation patterns of glaciers in large parts of High Mountain Asia (HMA) in complex ways due to the interaction of persistent cloud-cover, large temperature amplitudes, high atmospheric water content and high precipitation rates. While the ISM dominates in the southern and eastern regions, it progressively loses influence westward towards the Karakoram, where the influence of westerlies is predominant. Previous applications of energy- and mass-balance models for glaciers in HMA have been limited to single study sites (in Khumbu, Langtang and Parlung) and a few attempted to link model results to large-scale weather patterns. While these studies have helped to understand the energy- and mass-balance of glaciers in HMA under specific local climates, a regional perspective is still missing. In this study, we use a full energy- and mass-balance model together  with eight on-glacier AWS datasets around HMA to investigate how ISM conditions influence glacier-surface energy and mass balance. In particular, we look at how debris-covered and debris-free glaciers respond differently to the ISM, validating our results against independent in-situ measurements. This work is fundamental to the development of parameterizations of glacier melt for long-term hydrological studies and to the understanding of the present and future HMA cryosphere and water budget evolution.

How to cite: Fugger, S., Miles, E., McCarthy, M., Fyffe, C., Kneib, M., Fatichi, S., Yang, W., and Pellicciotti, F.: Understanding monsoon controls on the energy- and mass-balance of glaciers in High Mountain Asia, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-9690, https://doi.org/10.5194/egusphere-egu2020-9690, 2020.

EGU2020-18192 | Displays | HS2.1.2

What is the contribution of snow and glacier to discharge in Swiss alpine headwater catchments under climate change?

Daphné Freudiger, Irene Kohn, Kerstin Stahl, Markus Weiler, and Jan Seibert

Switzerland is often referred to as Europe’s Water Tower. During the melt season, water stored in the Alps as snow and ice feeds large European rivers such as the Rivers Rhine and Rhone. Under climate change conditions, snow and glacier melt contributions to discharge are expected to change dramatically. These changes might be very important during dry periods, when snow and glacier melt are the main sources of water. Assessing water availability in the future is essential for sustainable management of our water resources. Understanding how much melt water contributes to the discharge at different locations along the rivers is therefore necessary.

In this study, we used a customized version of the bucket-type hydrological model HBV-light, specially developed to assess the daily contribution of snow and glacier melt to discharge in a transient way. We assess the discharge components for 195 glacierized headwater catchments covering the entire Swiss Alps from 1973 to 2099. Hydrological processes in the Alps are spatially and temporally highly variable. Snow and glacier melt modelling are also challenged by data scarcity. Heterogeneously distributed meteorological measurement stations in high elevated and remote regions further complicate the representativity of the data. We show the advantages and challenges of using datasets from various sources as meteorological input data and for model calibration and validation of discharge, snow and glacier cover. In a second step, we applied a regionalization approach to defining model parameters for the ungauged catchments. A multi-criteria calibration was used to ensure that all hydrological processes are correctly represented within the model.

For future climate projections, we used the newly generated precipitation and temperature gridded products from MeteoSwiss for 45 climate models and for three emissions scenarios (RCP 2.6, RCP 4.5 and RCP 8.5). The results show that glacier peak water is already reached by most of the catchments and will be reached by all catchments during the first half of the Century for all three emissions scenarios. Under RCP 8.5, total glacier contribution summarized over all headwater catchments is 8% of total discharge under current climate and less than 2% at the end of the century. Snow melt will still be an important contribution to discharge during the first half of the century. In the second half of the century, however, snow melt contribution will significantly decrease from 34% (current climate) to 25% +/- 10% (2070-2099) of the total discharge. In contrary, rainfall contribution will increase from 58% to 72% +/- 15% of total discharge. Overall, the total annual discharge is expected to decrease slightly. The intensity of these changes in discharge contributions depends on the catchment elevation and large regional differences can be observed. The effects are much smaller under emission scenario RCP 2.6.

How to cite: Freudiger, D., Kohn, I., Stahl, K., Weiler, M., and Seibert, J.: What is the contribution of snow and glacier to discharge in Swiss alpine headwater catchments under climate change?, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-18192, https://doi.org/10.5194/egusphere-egu2020-18192, 2020.

EGU2020-859 | Displays | HS2.1.2

Hydrological response to warm and dry extremes in glacierized catchments: when and how are glaciers compensating?

Marit Van Tiel, Anne F. Van Loon, Jan Seibert, and Kerstin Stahl

Extreme warm and dry summer conditions often cause low-flow situations due to the precipitation deficit and increased evapotranspiration. In glacierized catchments, however, the same extreme weather conditions can lead to a very different hydrological response, namely increased streamflow because of increased glacier melt. In larger combined rainfed and glacierfed catchments, meltwater from glaciers can, thus, buffer the adverse hydrological effects of warm and dry spells. The question is how much glacier cover in a catchment is needed to counterbalance the hydrological processes that cause a decline in streamflow. Moreover, due to climate change, glaciers have been retreating, which affects the hydrological response and the buffering effect of glaciers. In this study, we analysed long-term streamflow records of around 60 glacierized catchments in Switzerland, Austria, Norway and Canada with varying glacier coverage. In addition, a few catchments were modelled to analyse some extreme events in more detail and perform sensitivity tests. Warm and dry spells were selected based on weather data for the catchments and the corresponding hydrological responses were investigated. The events were analysed taking into account catchment characteristics, such as glacier cover and elevation information, and antecedent conditions, such as snowfall in winter and precipitation amounts in the period before the warm and dry event. Results show that during extreme warm and dry spells small glacier cover fractions (< 10%) can already alleviate the otherwise emerging streamflow drought. Moreover, we see a clustering of warm and dry periods in recent years and a decreasing trend of summer streamflow in many catchments. Antecedent conditions appear to shape the individual summer streamflow responses. Overall, understanding the hydrological responses to warm and dry spells is essential due to projected increases in weather extremes. Especially in glacierized catchments, our results imply that with changing glacier cover due to global warming, changes in the buffering capacity of glacierized catchments during warm and dry periods can be expected.

How to cite: Van Tiel, M., Van Loon, A. F., Seibert, J., and Stahl, K.: Hydrological response to warm and dry extremes in glacierized catchments: when and how are glaciers compensating?, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-859, https://doi.org/10.5194/egusphere-egu2020-859, 2020.

EGU2020-8820 | Displays | HS2.1.2

Deriving water content from multiple geophysical properties of a firn aquifer in Southeast Greenland

Siobhan Killingbeck, Nicholas Schmerr, Lynn Montgomery, Adam Booth, Phil Livermore, Jonathan Guandique, Olivia Miller, Scott Burdick, Richard Forster, Lora Koenig, Anatoly Legchenko, Stefan Ligtenberg, Clément Miège, Kip Solomon, and Landis West

Warming of the polar ice sheets causes changes in the hydrological regime of surface layers of firn and ice. Surface meltwater may undergo perennial storage of liquid water above the firn-ice transition, which could slow sea level rise or cause sudden release events, when storage capacity is reached. Firn aquifers have been commonly observed within the lower percolation zone of the southeastern Greenland ice sheet during the past decade, and more recently, across some Antarctic ice shelves. Knowledge of the geographic extent and fractional liquid water content (and storage) of such aquifers will enable a better understanding of their effects on the sub- and en-glacial hydrologic system and is crucial for accurate predictions of the contribution of meltwater discharge to global sea level rise.

Quantitative geophysical analysis from surface observations can be used to infer hydrological properties of the firn and ice without time intensive direct drilling, providing an efficient spatial distribution of properties along with an estimate of their uncertainty. Furthermore, by combining multiple types of geophysical observations, joint inversions allow ambiguities of one methodology to be mitigated by resolution in the other.

Here, we demonstrate that this joint approach is a powerful complement to the conventional geophysical analysis of firn aquifers, by combining seismic, ground penetrating radar and borehole data to characterise aquifer properties, using the ‘MuLTI’ algorithm. In particular, we incorporate seismic shear wave velocities (Vs), derived from surface (Rayleigh) waves offering a promising means of distinguishing zones containing liquid water, into independent compressional wave velocity, density, and radar soundings of the water table. We find Vs decreases from 1600 m/s in the unsaturated firn above the water table at around 15 m depth, to 800 m/s through saturated ‘clean’ firn aquifer at around 25 m depth. However, at lower elevations, Vs increases to 1250 m/s through thicker, older firn aquifer where there are many ice lenses, which are interpreted to correspond with episodes of refreezing aquifer water as the system has evolved through time. With access to multiple seismic wave velocities (compressional and shear) through the aquifer, a more accurate estimate of liquid water content can be derived. Thus, the application of the MuLTI algorithm to this pressing new problem can deliver an accurate assessment of firn aquifer properties, and provide clear uncertainty limits which will be valuable for predictive modelling.

How to cite: Killingbeck, S., Schmerr, N., Montgomery, L., Booth, A., Livermore, P., Guandique, J., Miller, O., Burdick, S., Forster, R., Koenig, L., Legchenko, A., Ligtenberg, S., Miège, C., Solomon, K., and West, L.: Deriving water content from multiple geophysical properties of a firn aquifer in Southeast Greenland, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-8820, https://doi.org/10.5194/egusphere-egu2020-8820, 2020.

EGU2020-8441 | Displays | HS2.1.2

Influence of seasonally frozen ground on hydrological partitioning – a global systematic review

Pertti Ala-aho, Anna Autio, Joy Bhattacharjee, Elina Isokangas, Katharina Kujala, Hannu Marttila, Meseret Menberu, Leo-Juhani Meriö, Heini Postila, Anssi Rauhala, Anna-Kaisa Ronkanen, Pekka M. Rossi, Markus Saari, Ali Torabi Haghighi, and Björn Klöve

Seasonally frozen ground (SFG) occurs on ~25% of the Northern Hemisphere’s land surface, and the influence of SFG on water, energy, and solute fluxes is important in cold climate regions.  The hydrological role of permafrost is now being actively researched, but the influence of SFG has been receiving less attention. Intuitively, water movement in frozen ground is blocked by ice forming in soil pores that were open to water flow prior to freezing. However, it has been shown that the hydrological influence of SFG is insignificant in some cases, with soil remaining permeable to water even when frozen. There is a clear knowledge gap concerning (1) how intensively and (2) under what physiographical and climate conditions SFG influences hydrological fluxes. We conducted a systematic literature review examining the hydrological importance of SFG we found reported in 143 publications. We found a clear hydrological influence of frozen ground in small-scale laboratory measurements, but a more ambiguous effect when the spatial scale under study increased to hillslopes, catchments, or watersheds. We also found that SFG may be hydrologically less important in forested areas or in regions with deep snow cover. Our systematic review suggests that hydrological influence of SFG may become more important in a future warmer climate with less snow and intensified land use in high-latitude areas.

How to cite: Ala-aho, P., Autio, A., Bhattacharjee, J., Isokangas, E., Kujala, K., Marttila, H., Menberu, M., Meriö, L.-J., Postila, H., Rauhala, A., Ronkanen, A.-K., Rossi, P. M., Saari, M., Torabi Haghighi, A., and Klöve, B.: Influence of seasonally frozen ground on hydrological partitioning – a global systematic review, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-8441, https://doi.org/10.5194/egusphere-egu2020-8441, 2020.

EGU2020-17714 | Displays | HS2.1.2

Combining UAV LiDAR and Terrestrial Laser Scanning to investigate the impact of shrub expansion on local-scale Arctic snowpack distribution.

Maxim Lamare, Laurent Arnaud, Ghislain Picard, Maude Pelletier, and Florent Domine

Climate warming induces shrub expansion on Arctic herb tundra, with effects on snow trapping and hence snow depth. We have used UAV-borne LiDAR and Terrestrial Laser Scanning (TLS) to investigate the impact of shrub height on snow depth at two close sites near Umiujaq, eastern Canadian low Arctic, where dwarf birch and willow shrubs are expanding on lichen tundra. The first site features lichen and high shrubs (50-100 cm), a moderate relief, and a snowpack averaging 95 cm in spring. The second site consists of lichen and low shrubs (20-60 cm), more pronounced topography, and a deeper snowpack (101 cm). Digital Terrain and Surface Models were acquired in early fall to obtain topography and vegetation height. A Digital Surface Model obtained in spring produced snow depth maps at peak depth. TLS over a 400 m2 area produced time series of snow depth throughout the winter. TLS data show preferential snow accumulation in shrubs, but also preferential melting in shrubs during fall warm spells and in spring. UAV data at the first site show a strong correlation between vegetation height and snow depth, even after snow depth has exceeded vegetation height. This correlation is not observed at the second site, probably because snow depth there is much greater than vegetation height. These data show the need to reconsider some paradigms on snow-vegetation interactions, for example that vegetation does not affect snow accumulation beyond its height.

How to cite: Lamare, M., Arnaud, L., Picard, G., Pelletier, M., and Domine, F.: Combining UAV LiDAR and Terrestrial Laser Scanning to investigate the impact of shrub expansion on local-scale Arctic snowpack distribution., EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-17714, https://doi.org/10.5194/egusphere-egu2020-17714, 2020.

EGU2020-13112 | Displays | HS2.1.2

Estimation of snow water equivalent in a mountain range by using a dynamic regression approach

Antonio-Juan Collados-Lara, David Pulido-Velazquez, Eulogio Pardo-Igúzquiza, Esteban Alonso-González, and Juan Ignacio López-Moreno

The snow dynamics in alpine systems governs the hydrological cycle in these regions. However, snow data are usually limited due to poor accessibility and limited funds. On the other hand, the majority of scientific studies about snow resources are carried out at mountain slope or basin scale. The main goal of this work is to propose a parsimonious methodology to estimate snow water equivalent (SWE) at mountain range scale. A regression model that includes non-steady explanatory variables is proposed to assess snow depth dynamic based on the information coming from snow depth point observations, a digital elevation model, snow cover area from satellite and a precipitation index representative of the area. The main advantages of the method are its applicability in cases with limited information and in mountain ranges scales. In the proposed methodology different regression model structures with different degrees of complexity are calibrated combining steady and non-steady explanatory variables (elevation, slope, longitude, latitude, eastness, northness, maximum upwind slope, radiation, curvature, accumulated snow cover area and precipitation in a temporal window) and four basic mathematical transformations of these variables (square, root square, inverse and logarithm). In the case of the temporal variables different time windows to define the accumulated values of the explanatory indices have been tested too. We have applied the methodology in a case study, the Sierra Nevada mountain range (Southern Spain), where the calibration has been performed by using the snow depth data observation provided by the ERHIN program which have a very low temporal frequency (2 or 3 measurement per year). When only non-steady explanatory variables are considered, the coefficient of determination of the global spatial estimation model is 0.55. When we also include non-steady variables we obtain an approach with a coefficient of determination of 0.62. We have also calibrated a new regression approach by using, in addition to the ERHIN program information, data coming from a detailed temporal series of snow depth in a new specific location, which has allow to obtain models with R² of 0.59 (for steady explanatory variables) and 0.64 (including also non-steady explanatory variables). The dynamic of the snow density in the mountain range has been estimated by means of a physically based simulation driven by WRF data. Combining the snow depth and the density approaches we have estimated the final SWE in Sierra Nevada. 

This research has been partially supported by the SIGLO-AN project (RTI2018-101397-B-I00) from the Spanish Ministry of Science, Innovation and Universities (Programa Estatal de I+D+I orientada a los Retos de la Sociedad).

How to cite: Collados-Lara, A.-J., Pulido-Velazquez, D., Pardo-Igúzquiza, E., Alonso-González, E., and López-Moreno, J. I.: Estimation of snow water equivalent in a mountain range by using a dynamic regression approach, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-13112, https://doi.org/10.5194/egusphere-egu2020-13112, 2020.

EGU2020-19350 | Displays | HS2.1.2

Exploitation of X-band SAR images and ground data for SWE retrieval through a machine learning technique

Ludovica De Gregorio, Francesca Cigna, Giovanni Cuozzo, Alexander Jacob, Simonetta Paloscia, Simone Pettinato, Emanuele Santi, Deodato Tapete, and Claudia Notarnicola

Snow cover is a critical geophysical parameter for Earth climate and hydrological systems. It contributes to regulate the Earth surface temperature and represents an important water storage that is slowly released during the melting season and contributes to the river discharge.

The parameter that characterizes the hydrological importance of snow cover is the snow water equivalent (SWE). An accurate estimation of the spatial and temporal distribution of SWE in mountain environments is still a relevant challenge for the scientific community, due to the complex topography that causes a high spatial heterogeneity in snow distribution, by reducing the representativeness of traditional pointwise in situ measurements.

Several efforts have been done to develop new methods for estimating snow-related parameters. In particular, the large-scale monitoring of the Earth’s surface from space-borne sensors has proven to be very effective, by improving the spatialization of land surface parameters. In the last decades, scientists have extensively investigated the potential of Synthetic Aperture Radar (SAR) data for deriving SWE. Unlikely to visible sensors, microwave sensors do not depend on the presence of sunlight and are not affected by the presence of clouds.

In this context, the main objective of this work is to exploit the already demonstrated sensitivity of the X-band SAR to snow [1] for estimating the SWE in the mountainous area of South Tyrol, in north-eastern Italy. For this purpose, the information derived from X-band SAR imagery acquired by the Italian Space Agency (ASI)’s COSMO-SkyMed constellation in StripMap HIMAGE mode at 3 m ground resolution is exploited together with ground measurements of SWE, which have been chosen by selecting the dates corresponding to the satellite acquisitions in the study period (2013-2015). In order to increase the training dataset, further backscattering coefficients have been simulated by using an implementation of the Dense Media Radiative Transfer (DMRT) theory, based on the Quasi-Crystalline Approximation (QCA) of Mie scattering of densely packed Sticky spheres [2]. Moreover, to optimize the satellite acquisition and use as much corresponding SWE data as possible, we integrated the ground dataset with other SWE values obtained as explained in [3] by means of a data fusion approach involving the snow model AMUNDSEN.

This work is carried out by EURAC, CNR/IFAC and ASI in the framework of the 2019-2021 project ‘Development of algorithms for estimation and monitoring of hydrological parameters from satellite and drone’, funded by ASI under grant agreement n.2018-37-HH.0.

 

References

[1] Pettinato, S. et al. (2012). The potential of COSMO-SkyMed SAR images in monitoring snow cover characteristics. IEEE Geoscience and Remote Sensing Letters, 10(1), 9-13.

[2] Tsang, L. et al. (2007). Modeling active microwave remote sensing of snow using dense media radiative transfer (DMRT) theory with multiple-scattering effects. IEEE Transactions on Geoscience and Remote Sensing, 45(4), 990-1004.

[3] De Gregorio, L. et al. (2019). Improving SWE Estimation by Fusion of Snow Models with Topographic and Remotely Sensed Data. Remote Sensing, 11(17), 2033.

 

How to cite: De Gregorio, L., Cigna, F., Cuozzo, G., Jacob, A., Paloscia, S., Pettinato, S., Santi, E., Tapete, D., and Notarnicola, C.: Exploitation of X-band SAR images and ground data for SWE retrieval through a machine learning technique, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-19350, https://doi.org/10.5194/egusphere-egu2020-19350, 2020.

EGU2020-22457 | Displays | HS2.1.2

Spatiotemporal Variability of Snow Depth in Subarctic Environment Using Unmanned Aircraft Systems (UAS)

Anssi Rauhala, Leo-Juhani Meriö, Pertti Ala-aho, Pasi Korpelainen, Anton Kuzmin, Timo Kumpula, Rauno Heikkilä, Bjørn Kløve, and Hannu Marttila

Seasonal snow accumulation and melt dominates the hydrology in high latitude areas, providing water storages for both ecological and human needs. However, until recent years there has been a lack of cost-efficient way to measure the spatiotemporal variability of the snow depth and cover in high resolution. Unmanned aircraft systems (UAS) can offer spatial resolutions up to few centimeters, depending on the weather and light conditions, camera quality and drone specification. We used multiple different quadcopters and a fixed wing UAS to determine and analyze the spatiotemporal variability of snow depth and cover in three test plots with different land-cover types (forested slope, open peatland, and peatland-forest) in subarctic northern Finland, where weather and light conditions are challenging. Five measurement campaigns were conducted during winter 2018/2019 and a snow-free bare ground survey after snowmelt. Snow depth maps were constructed using Structure from Motion (SfM) photogrammetry technique and by differentiating the acquired models from snow-covered and snow-free surveys. Due to poor sub-canopy penetration with UAS-SfM method, tree masks were utilized to remove canopy effects prior to analysis. The snow depth maps produced with different UAS were compared to in situ snow course and an automatic ultrasonic measurement data. We highlight the difficulties of working in subarctic winter conditions and discuss the accuracy of UAS-derived snow depth maps. We show that the UAS-derived snow depth measurements agree well with manual snow survey measurements and UAS are suitable method for extending the spatial snow data coverage, whereas a continuous point snow depth measurement is unable to accurately present sub-catchment scale snow depth variability. Furthermore, the spatiotemporal variability of snow accumulation and melt between and within different land cover types is presented.

How to cite: Rauhala, A., Meriö, L.-J., Ala-aho, P., Korpelainen, P., Kuzmin, A., Kumpula, T., Heikkilä, R., Kløve, B., and Marttila, H.: Spatiotemporal Variability of Snow Depth in Subarctic Environment Using Unmanned Aircraft Systems (UAS), EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-22457, https://doi.org/10.5194/egusphere-egu2020-22457, 2020.

EGU2020-157 | Displays | HS2.1.2

Soil moisture dynamics in winter under heavy snowfall conditions in Shonai (Japan)

Alexander Brandt, Qiqin Zhang, Maximo Larry Lopez Caceres, and Hideki Murayama

Yamagata prefecture, facing the Japan Sea, is one of the heavy snow fall regions of the world. Around half of the annual precipitation of around 3000 mm falls in winter as snow, producing snow covers of more than three meters depth.  However, air temperature is around 0°C in winter and therefore relatively warm. Hence, snow density becomes 0.5 g/cm³ already early in the snow accumulation phase. To qualify and quantify interactions, three spots on a slope, forested with Japanese cedar (Cryptomeria japonica), have been selected to compare relationships on top, at the middle and at the bottom of snow covered slopes. The site represents the majority of mountain forests in north-eastern Japan. Monitoring soil and air temperature as well as precipitation and soil moisture we found strong interactions between the three hydrological regimes (precipitation, snow cover and soil) in winter. Soil did not freeze and hence volumetric soil moisture content changed during the winter season. Several sharp significant increases of soil moisture have been measured before the snow melt period even started. High rates of soil moisture increase together with an increase of Snow Water Equivalent (SWE) have been found to be caused by rain-on-snow events. In contrast, smaller rates of soil moisture increase in peaks were correlated with a decrease in SWE and therefore a snowmelt process. The interactions of snow cover and soil have been found to be different in the three different spots at the slope. Soil at the bottom of a slope reacts significantly to the highest number of events; soil on the slope reacts only to some events, but more intensively. Thus, most of the water is moving within the snowpack down the slope, increasing the SWE. Thereafter water reaches the soil surface and infiltrates it. This has been found to be also one reason for the formation of depth hoars and therefore the risk of avalanches.

To conclude, hydrological regimes in north-eastern Japan interact during the whole year due to winter air temperatures around 0°C and soil which does not freeze. The shape of peaks in soil moisture can be used to distinguish between rain and snowmelt causing the soil moisture increase. Various preferential flow patterns at different spots on a slope are an excellent basis for further studies and a basis for further monitoring and modelling.

How to cite: Brandt, A., Zhang, Q., Lopez Caceres, M. L., and Murayama, H.: Soil moisture dynamics in winter under heavy snowfall conditions in Shonai (Japan), EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-157, https://doi.org/10.5194/egusphere-egu2020-157, 2020.

EGU2020-7995 | Displays | HS2.1.2

Trends of the Degree-Day Factors in the mountainous regions

Muhammad Fraz Ismail

Trends of the Degree-Day Factors in the mountainous regions

Muhammad Fraz Ismail1, 2, Prof. Dr. –Ing. Markus Disse1, Prof. Dr. –Ing. Wolfgang Bogacki2,

Alexander Brandt3, M. Larry Lopez C.3

 

1 Chair of Hydrology and River Basin Management, Department of Civil, Geo and Environmental Engineering, Technical University of Munich.

2 Department of Civil Engineering, Koblenz University of Applied Sciences.

3 Faculty of Agriculture, Yamagata University, Tsuruoka, Japan.

 

Melt generated through snow and glaciers are considered to be a vital fresh water resource because they store the solid winter precipitation as then act as a reservoir to provide water when it is mostly needed i.e. during the summer season. Recently, a lot of studies based on hydrological modelling showed that the changing climate will adversely affect the snow and glacial melt patterns around the globe. Considering this situation it is quite critical to know more about these melting processes and the factors driving them.

Degree-day approach for simulating the flows generated through the snow and glacial melt has proved to be a handsome one because it uses the temperatures as an index variable to address the complex energy balances as well as its only dependency over the air temperatures to generate the melt make it feasible especially for the high mountainous data scare regions (e.g. Upper Indus Basin). Degree-day models use the Degree-Day Factor (DDF) as a ‘key’ parameter which transforms one degree-day [°C.day-1] into daily melt depth [mm.day-1]. Literature enlightens that the DDF is not a constant parameter but it changes with the ripening of the snowpack.

In the present research, snow measurement datasets from three different locations e.g. Japan (Enshurin 173m a.s.l.), Germany (Brunnenkopfhütte 1602m a.s.l.), and Pakistan (Deosai 4149m a.s.l.) have been collected and evaluated for the estimation of the DDFs. Initial findings show that there exists a considerable spatio-temporal variation of the DDFs. Which ranges from 0.3 – 6.8 [mm°C-1 day-1] in the German Alps, 0.2 – 7.9 [mm°C-1 day-1] in Yamagta Forest Japan and reaches ≥10 [mm°C-1 day-1] in the Himalayan ranges during the snowmelt season.

In general, the DDFs show an increasing trend during the snowmelt season at different elevations, which not only demonstrates the altitude influence on the variability of the DDFs but also links to changing snow densities. Latter suggests that the DDFs should not be taken as constant because it changes with the location and needs to be estimated for different regions.

 

KEYWORDS: Degree-Day Factor, Snow and glacial melt, Measurements

How to cite: Ismail, M. F.: Trends of the Degree-Day Factors in the mountainous regions, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-7995, https://doi.org/10.5194/egusphere-egu2020-7995, 2020.

EGU2020-13207 | Displays | HS2.1.2

Residence time of nitrogen deposit in a nival subalpine catchment using the hyper-resolution ParFlow-CLM-EcoSLIM critical zone model.

Jean-Martial Cohard, Alix Reverdy, Didier Voisin, Basile Hector, Aniket Gupta, and Romain Biron

Mountain regions represent a particular challenge for critical zone modelling as snowpack interacts with soils, vegetation, surface water and atmosphere and plays a primary role on the water transfers but also on the carbon and nitrogen cycles. Indeed, in these environments ecosystems are adapted to a snow regime under change due to the rise in the 0°C isotherm. In addition, atmospheric nitrogen deposition, a product of industrial activity carried by valley winds and mesoscale atmospheric circulation, already impacts some high-altitude ecosystems by modifying nutrient flows (nitrogen and carbon in particular). These combined forcings could lead to major ecosystem changes (distribution of water, carbon and nitrogen flows, growth rates, species, etc.). Anticipating this evolution, and the associated flows (CO2, nitrogen, water) under this double constraint, remains problematic due to the lack of adapted models.

In this study, we use the Parflow/CLM/Ecoslim model on a small (17ha) nival subalpine catchment close to Lautaret Pass (French Alps) where meteorological and hydrological parameters are measured together with snowpack survey and chemical concentrations measurements in the air, the rivers, the snowpack the vegetation and the ground. Simulations are constrained by a spatially distributed forcing and evaluated from snow pack dynamic and ET measurements. The simulations allow us to estimate the Nitrogen quantities that can be processed by vegetation and those drained in river flows. The estimation of the residence times is then calculated from the velocity field in the catchment. The wide snow cover time distribution leads to wide distribution resident time for any particle deposit. This can impact nitrogen chemical history and any other chemical compounds in the snow pack and the ground even for such small scales.

How to cite: Cohard, J.-M., Reverdy, A., Voisin, D., Hector, B., Gupta, A., and Biron, R.: Residence time of nitrogen deposit in a nival subalpine catchment using the hyper-resolution ParFlow-CLM-EcoSLIM critical zone model., EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-13207, https://doi.org/10.5194/egusphere-egu2020-13207, 2020.

EGU2020-9037 | Displays | HS2.1.2

CRAMPON: A Particle Filter to assimilate sparse snowpack observations into a semi-distributed geometry

Bertrand Cluzet, Matthieu Lafaysse, Marie Dumont, Emmanuel Cosme, and Clément Albergel

In mountainous areas, detailed snowpack models are essential to capture the high spatio-temporal variability of the snowpack. This task is highly challenging, and models suffer from large simulation errors. In these regions, in-situ observations are scarce, while remote sensing observations are generally patchy owing to complex physiographic features (steep slopes, forests, shadows,...) and weather conditions (clouds). This point is stressing the need for a spatially coherent data assimilation system able to propagate the informations into unobserved locations.

In this study, we present CRAMPON (CRocus with AssiMilation of snowPack ObservatioNs), an ensemble data assimilation system ingesting snowpack observations in a spatialized context. CRAMPON quantifies snowpack modelling uncertainties with an ensemble and reduces them using a Particle Filter. Stochastic perturbations of meteorological forcings and the multi-physical version of Crocus snowpack model (ESCROC) are used to build the ensemble. Two variants of the Sequential Importance Resampling Particle Filter (PF) were implemented to tackle the common PF degeneracy issue that arises when assimilating a large number of observations. In a first approach (so-called global approach), the observations information is spread across topographic conditions by looking for a global analysis. Degeneracy is mitigated by inflating the observation error covariance matrix, with the side effect of reducing the impact of the assimilation. In a second approach (klocal), we propagate the information and mitigate degeneracy by a localisation of the PF based on background correlation patterns between topographic conditions.

Here, we investigate the ability of CRAMPON to globally benefit from partial observations in a conceptual semi-distributed domain which accounts for the main features of topographic-induced snowpack variability. We compare simulations without assimilation with experiments assimilating synthetic observations of the Height of Snow and VIS/NIR reflectance. This setup demonstrates the ability of CRAMPON to spread the information of various snow observations into unobserved locations.

How to cite: Cluzet, B., Lafaysse, M., Dumont, M., Cosme, E., and Albergel, C.: CRAMPON: A Particle Filter to assimilate sparse snowpack observations into a semi-distributed geometry, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-9037, https://doi.org/10.5194/egusphere-egu2020-9037, 2020.

Himalayan mountain region lying in the northern piece of Indian sub-continent is among those zones which bears the most geologically fragile situations and are additionally a vault of biodiversity, new water stockpiling and environment administrations. The Himalaya is one of the world’s largest and mostly inaccessible area of glaciers outside the polar regions and provides glacier-stored water to the major perennial rivers of India throughout the year and to their river basins also. Glacier is a large ice mass formed by accumulation, compaction and re-crystallization of snow and firn due to stress of its own weight. Glacier with steep slopes of bedrock may retreat with slower rate or may even advance because downslope movement of glacier will continuously feed ice to lower altitude. Increased retreating rate of glaciers can be considered as an indicator of climate change. In the course of recent three decades, the occurred changes can be explained with exploitative land utilization which is among the primary drivers of changing snow cover, vegetation covers and profitability in western Himalayas locale. In a region where field-based research is tiring because of heterogenous and high elevation, measuring the changes in aforesaid using Remote Sensing techniques can give basic data regarding variating patterns of Snowfall and Precipitation. This paper studies the trend analysis of changing Snowfall and Precipitation patterns using SWAT and MODIS data (1979–2014 and 1999 to Present) over Uttarakhand Himalaya and its association with altitudinal gradient. This paper investigates the trends in maximum (Pmax), minimum (Pmin) & mean (Pmean) Snowfall and Precipitation in the annual, seasonal and monthly time-scales for 54 stations in the 5 regions of Uttarakhand’s Western Himalayan region which are categorized on the basis of elevation, from year 1979-2014. Statistical approaches are used to examine the effect of change in pattern of snowfall and precipitation upon the phenology of vegetation, fresh water ecosystems, agricultural productivity, decreasing snow line, increasing tree line & change in duration of the seasons etc of the study area.

How to cite: Pandey, A. and Palni, S.: Trend analysis of Changing Pattern of Snowfall and Precipitation over the Time Period of 1979 to 2014 in Alpine region of Uttarakhand, Western Himalaya, India , EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-565, https://doi.org/10.5194/egusphere-egu2020-565, 2020.

EGU2020-1383 | Displays | HS2.1.2

Global Snow Cover Extent Mapping Using Sentinel-1

Ya-Lun Tsai, Soner Uereyen, Andreas Dietz, Claudia Kuenzer, and Natascha Oppelt

Seasonal snow cover extent (SCE) is a critical component not only for the global radiation balance and climatic behavior but also for water availability of mountainous and arid regions, vegetation growth, permafrost, and winter tourism. However, due to the effects of the global warming, SCE has been observed to behave in much more irregular and extreme patterns in both temporal and spatial aspects. Therefore, a continuous SCE monitoring strategy is necessary to understand the effect of climate change on the cryosphere and to assess the corresponding impacts on human society and the environment. Nevertheless, although conventional optical sensor-based sensing approaches are mature, they suffer from cloud coverage and illumination dependency. Consequently, spaceborne Synthetic Aperture Radar (SAR) provides a pragmatic solution for achieving all-weather and day-and-night monitoring at low cost, especially after the launch of the Sentinel-1 constellation. 

In the present study, we propose a new global SCE mapping approach, which utilizes dual-polarization intensity-composed bands, polarimetric H/A/α decomposition information, topographical factors, and a land cover layer to detect the SCE. By including not only amplitude but also phase information, we overcome the limitations of previous studies, which can only map wet SCE. Additionally, a layer containing the misclassification probability is provided as well for measuring the uncertainty. Based on the validation with in-situ stations and optical imagery, around 85% accuracy of the classification is ensured. Consequently, by implementing the proposed method globally, we can provide a novel way to map high resolution (20 m) and cloud-free SCE even under cloud covered/night conditions. Preparations to combine this product with the optical-based DLR Global SnowPack are already ongoing, offering the opportunity to provide a daily snow mapping service in the near future which is totally independent from clouds or polar darkness.

How to cite: Tsai, Y.-L., Uereyen, S., Dietz, A., Kuenzer, C., and Oppelt, N.: Global Snow Cover Extent Mapping Using Sentinel-1, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-1383, https://doi.org/10.5194/egusphere-egu2020-1383, 2020.

EGU2020-1285 | Displays | HS2.1.2

Insights into precipitation orographic enhancement from snow-course data and their value for improved hydrologic predictions

Francesco Avanzi, Giulia Ercolani, Simone Gabellani, Edoardo Cremonese, Umberto Morra di Cella, Paolo Pogliotti, Gianluca Filippa, Sara Ratto, and Hervé Stevenin

Precipitation enhancement along elevation gradients is the result of complex interactions between synoptic-circulation patterns and local topography. Since precipitation measurements at high elevation are often biased and sparse, predicting precipitation distribution in mountain regions is challenging, despite this being a key step of hydrologic-forecasting procedures and of water management in general. By acting as a natural precipitation gauge, the snowpack can provide useful information about precipitation orographic enhancement, but the information content of snow-course measurements in this regard has been generally underappreciated. We leveraged 70,000+ measurements upstream five reservoirs in Valle d’Aosta, Italy, to show how manual and radar snow courses can be used to estimate precipitation lapse rates and consequently improve predictions of hydrologic models. Snow Water Equivalent above 3000 m ASL can be more than 4-5 times cumulative seasonal precipitation below 1000 m ASL, with elevational gradients up to 1000 mm w.e. / km ASL. Enhancement factors estimated by blending precipitation-gauge and snow-course data are highly seasonal and spatially variable, with exponential or linear profiles with elevation depending on the year. Blended gauge - snow-course precipitation lapse rates can be used to infer precipitation in ungauged areas and compensate for elevation gradients in an iterative, two-step distribution procedure of precipitation based on modified Kriging. Coupling this precipitation-distribution procedure with a snow model (S3M) shows promising improvements in Snow Water Equivalent estimates at high elevations.

How to cite: Avanzi, F., Ercolani, G., Gabellani, S., Cremonese, E., Morra di Cella, U., Pogliotti, P., Filippa, G., Ratto, S., and Stevenin, H.: Insights into precipitation orographic enhancement from snow-course data and their value for improved hydrologic predictions, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-1285, https://doi.org/10.5194/egusphere-egu2020-1285, 2020.

EGU2020-3421 | Displays | HS2.1.2

Spatial and temporal variation of snow cover in the Himalayan and Karakorum region using MODIS data (2000-2019)

Jaydeo Kumar Dharpure, Ajanta Goswami, and Anil V. Kulkarni

The Himalayan and Karakorum (H-K) region comprise the highest amount of snow and ice cover outside the Polar Regions. The H-K region is grouped into four-part, i.e., the Karakorum (KK), Western (WH), Central (CH), and Eastern Himalayas (EH), based on climate and geographic location. The EH and CH mainly feed by summer-monsoon snowfall, whereas the KK and WH are winters accumulated. This regional variability of climate will affect the water availability for hydropower generation, agriculture, and ecosystem. Therefore, the mapping and monitoring of snow cover change over the study area played an essential role in the context of climate change. The snow cover area (SCA) was observed using Moderate-resolution Imaging Spectroradiometer (MODIS) daily snow cover products version 6 during 2000-2019. Different cloud removal techniques (e.g., multi-sensor, temporal, spatial, regional snow line, multiday backward) are applied to reduce the cloud cover pixels over snow pixels of the MODIS data. The mean annual SCA of the H-K region is ∼26.4% of the total geographical area during the study period. The statistical trend analysis of mean monthly, seasonal, and annual SCA is examined using Mann-Kendal and Sen’s slope test. The mean yearly SCA of the H-K region shows an increasing trend during 2000-2009 and start decreasing significantly during 2009-2019. Similar results are observed in the KK, WH, CH, and EH, which shows a decreasing trend of mean annual SCA since 2009. The mean seasonal SCA shows a significant decreasing trend in summer (June to September) and winter (December to February) since 2009, suggesting a seasonal shift or change in snow cover. Overall, the winter shows an insignificant decreasing trend in comparison to the other seasons during 19 hydrological years (2000-01 to 2018-19). The mean monthly minimum SCA observed in August for the KK and WH, July for the CH, and June for the EH. However, the mean maximum SCA in February for the KK, WH, CH, and March for the EH. The snow cover depletion curve suggests that the maximum SCA in February and minimum in August of the entire region during the study period. The seasonal variation of SCA can be highly related to the influence of monsoonal patterns in the region.

How to cite: Dharpure, J. K., Goswami, A., and Kulkarni, A. V.: Spatial and temporal variation of snow cover in the Himalayan and Karakorum region using MODIS data (2000-2019), EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-3421, https://doi.org/10.5194/egusphere-egu2020-3421, 2020.

EGU2020-5456 | Displays | HS2.1.2

Significance of meltwater in estimating runoff using Budyko framework in Northwest Xinjiang, China

Jie Bai, Junli Li, Tie Liu, and Anmin Bao

Budyko framework has been widely used to estimate the partitioning of precipitation into evapotranspiration and runoff as a function of an aridity index (i.e., ratio of potential evapotranspiration to precipitation) in catchments where snow or glaciers are absent. Where snow or glaciers exist, meltwater from either may considerably affect the performance of the Budyko framework. However such effects have not been investigated in the Xinjiang territory of Northwest China, which features many meltwater-dependent river systems. To analyze the effects of meltwater on hydrological cycles in Xinjiang, we utilized a calibrated hydrological model (Soil and Water Assessment Tool, SWAT) to estimate meltwater from snow or glaciers. The water budgets of 21 catchments across three major mountain ranges of Xinjiang showed that normalized contributions of meltwater to river runoff were respectively 89.9%, 77.0%, and 55.6% in the catchments of Altay, Kunlun and Tienshan Mountains. The results showed that the catchments of Altay Mountains with the highest meltwater ratio (defined as the ratio of meltwater to the sum of meltwater and rainfall, 0.572 ± 0.075) had the lowest Budyko parameter ω (1.238), while those of Tienshan Mountains with the lowest meltwater ratio (0.239 ± 0.143) had the highest ω value (1.348). This indicated that the Budyko parameter ω was negatively correlated to meltwater ratio across three mountains. Incorporating meltwater from snow and glaciers into the Budyko framework significantly increased the values of ω in all three mountain ranges, indicating that the Budyko framework without inclusion of meltwater could under-estimate evapotranspiration in Xinjiang, China. There results derived from this research also implied that both surface runoff and evapotranspiration may increase under a warming climate in mountain areas.

How to cite: Bai, J., Li, J., Liu, T., and Bao, A.: Significance of meltwater in estimating runoff using Budyko framework in Northwest Xinjiang, China, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-5456, https://doi.org/10.5194/egusphere-egu2020-5456, 2020.

EGU2020-5277 | Displays | HS2.1.2

A first attempt to model an Artificial Ice Reservoir (Ice Stupa) using a simple energy balance approach

Suryanarayanan Balasubramanian, Martin Hoelzle, Michael Lehning, Sonam Wangchuk, Johannes Oerlemans, and Felix Keller

Artificial Ice Reservoirs (AIRs, also called icestupas) have been successful in storing water during winter and releasing the water during spring and summer. Therefore, they can be seen as a vital fresh water resource for irrigation in dry environments. Many different forms of AIRs do exist and not many studies have tried to model theses ice structures.
We will present simulations of the most important physical processes that causes the formation and melt of AIRs using one dimensional equations governing the heat transfer, vapour diffusion and water transport of a phase changing water mass. For validation, an AIR was constructed in Schwarzsee region in the Canton of Fribourg, Switzerland. Meteorological data in conjunction with fountain discharge data was measured. According to the model, the Schwarzsee AIR was able to store and discharge 850 litres or  3.7 percent of all the water sprayed over a duration of 41 days. Alternate model scenarios will also be presented to show how this freezing efficiency can be increased.

How to cite: Balasubramanian, S., Hoelzle, M., Lehning, M., Wangchuk, S., Oerlemans, J., and Keller, F.: A first attempt to model an Artificial Ice Reservoir (Ice Stupa) using a simple energy balance approach, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-5277, https://doi.org/10.5194/egusphere-egu2020-5277, 2020.

EGU2020-9242 | Displays | HS2.1.2

Recent patterns of discharge and sediment output of the Gorner Glacier, Switzerland

Günther Prasicek, François Mettra, Stuart Lane, and Frédéric Herman

Recent climate change is causing rapid retreat of alpine glaciers around the globe. As ice melts and glaciers thin, glacier motion and subglacial processes will change. One of the most relevant aspects for down-valley environments, settlements and infrastructure is the potential change in flow discharge and sediment output.

Here we present the results of an ongoing monitoring program at the Gorner Glacier, Switzerland, the second-largest glacier system in the European Alps.  During the melt season of 2018 and 2019, stage and turbidity were monitored with a 5 minute frequency along a turbulent section of the glacial river, located approximately 1 km downstream of the glacier terminus. For calibration of the turbidity measurements, daily water samples were obtained with an automated pump sampler, supported by additional intermittent manual sampling. The data is complemented by a discharge time series that also contains information on the flushing of a bedload trap at the hydro power weir located about 2 km downstream of the glacier terminus. The discharge and flushing data have a resolution of 15 minutes.  Turbidity and discharge allow estimation of the output of suspended load, while the flushing data inform about bedload. We further measured total organic carbon content of the water samples to infer the water and sediment source.

Data suggest a clear seasonal pattern, not only in discharge and sediment output, but also in suspended sediment concentration (SSC). While SSC is high during snow melt and in early summer, it decreases rapidly in July and stays at similar levels until September. This may indicate exhaustion of sediment storage beneath the glacier, but could also result from a change in subglacial regime, e.g. from a decrease in subglacial water pressure due to the progressive opening of subglacial cavities during the melt season. High fractions of organic carbon, presumably due to lateral sediment input from hillslopes, occur during storms throughout the entire season.

How to cite: Prasicek, G., Mettra, F., Lane, S., and Herman, F.: Recent patterns of discharge and sediment output of the Gorner Glacier, Switzerland, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-9242, https://doi.org/10.5194/egusphere-egu2020-9242, 2020.

EGU2020-9305 | Displays | HS2.1.2

Impact of satellite and in situ data assimilation on hydrological predictions

Jude Lubega Musuuza, Louise Crochemore, David Gustafsson, Rafael Pimentel, and Ilias Pechlivanidis

The assimilation of different satellite and in-situ products generally improves the hydrological model predictive skill. Most studies have focused on assimilating a single product at a time with the ensemble size subjectively chosen by the modeller. In this study, we use the European-scale Hydrological Predictions for the Environment hydrological model in the Umeälven catchment in northern Sweden with the stream discharge and local reservoir inflow as target variables to objectively choose an ensemble size that optimises model performance. We further assess the effect of assimilating different satellite products namely snow water equivalent, fractional snow cover, and actual and potential evapotranspiration; as well as in situ measurements of river discharge and local reservoir inflows. We finally investigate the combinations of those products that improve model predictions of the target variables and how the model performance varies through the year for those combinations. We found that an ensemble size of 50 was sufficient for all products except the reservoir inflow, which required 100 members and that in situ products outperform satellite products when assimilated. In particular, potential evapotranspiration alone or as combinations with other products did not generally improve predictions of our target variables. However, assimilating combinations of the snow products, discharge and local reservoir without ET products improves the model performance.

How to cite: Musuuza, J. L., Crochemore, L., Gustafsson, D., Pimentel, R., and Pechlivanidis, I.: Impact of satellite and in situ data assimilation on hydrological predictions, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-9305, https://doi.org/10.5194/egusphere-egu2020-9305, 2020.

EGU2020-10440 | Displays | HS2.1.2

Mathematical simulation of melting mountain glaciers

Egor Belozerov, Ekaterina Rets, and Viktor Popovnin

Freshwater shortage is one of the global problems of our time. Glaciers contain a large amount of freshwater on the Earth. Nowadays mountain glaciation is decreasing almost throughout the world (Panov, 1993; Duethmann et al., 2016; Fausto et al. 2016). This effect leads to an increase in the water content of mountain rivers, but also cause a decrease in glaciers freshwater reserves (Trenberth et al., 2007; Sorg et al., 2012). This impact is already felt in the arid regions of our planet. Recently in Central Asia was observed a shortage of water resources. According to the estimates, the total area and mass decrease of the Tien Shan glaciers, from 1961 to 2012, amountes to 18 ± 6% and 27 ± 15% (Farinotti et al., 2015). The degradation of the area and volume of the Tien Shan glaciers, in the period from 1961 to 2012, was 18 ± 6% and 27 ± 15% (Farinotti et al., 2015). About 15% of the runoff in the Republic of Kyrgyzstan is fed by glacial nutrition, but this contribution may even be 1.5-3 times greater during the warm season (Dikikh et al., 1995; Kemmerikh, 1972). The average annual rivers runoff in the Republic of Kyrgyzstan increased from 47.1 km3 (~ 1947–1972) to 50 km3 (1973–2000) (Mamatkanov et al., 2006). The representative glacier of the Central Caucasus - Dzhankuat can serve as an example of depletion of freshwater in the glaciers of the Caucasus. Over the past decades, since 1974, the Dzhankuat glacier has lost large volumes - almost twice, and at the time of 2013 it is equal to 0.077 ± 0.002 km3. From 2006 to 2015 the volume of the Dzhankuat glacier decreased by 25%, as a consequence, there is an increase in the rate of degradation (Lavrentiev et al., 2014).

In this article is presented mathematical simulation, which allows to solve a number of problems. One of the most important problem is the calculation of the water supply into the river network because of snow and ice melting in mountain areas. Weather conditions are taken into account in the simulation calculation of snow and ice melting over the entire glacier surface.

This work is supported by the Presidential Russian Federation grant №MK-2936.2019.5

How to cite: Belozerov, E., Rets, E., and Popovnin, V.: Mathematical simulation of melting mountain glaciers, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-10440, https://doi.org/10.5194/egusphere-egu2020-10440, 2020.

EGU2020-9999 | Displays | HS2.1.2

Changes in seasonal snowpack in mountain catchments in Czechia

Ondrej Nedelcev and Michal Jenicek

Seasonal snowpack is an important part of the water cycle and it has a large influence on runoff regime in mountain catchments of Central Europe. However, snow water equivalent (SWE) is decreasing in many mountain regions over the last decades and spring snowmelt occurs earlier in the year. This study aimed 1) to analyse long-term changes and trends in selected snowpack characteristics, such as SWE, snow cover duration, snowmelt onset and melt-out in 40 mountain catchments in Czechia in the period 1965–2014 and 2) to relate the detected changes to changes in air temperature and snowfall fraction at different elevations. Since the availability of time series of measured SWE at a catchment scale is limited, a conceptual semi-distributed hydrological model HBV-light was used to simulate daily SWE for defined elevation zones. Besides SWE, the model simulated other water balance components, such as runoff, soil moisture and groundwater recharge. The integrated multi-variable model calibration procedure was used to calibrate the model. Both observed runoff and SWE were used for evaluation of the model performance. Seasonal and monthly mean of SWE, as well as snow cover duration, snowmelt onset, snowmelt rates and melt-out were calculated for individual catchments and elevation zones. The non-parametric Mann-Kendall test was used to detect potential trends in simulated time series. The results showed significant decreasing trends in snowfall fraction for all catchments and elevations in the study period mostly due to an increase in air temperature. This resulted in a decrease in snow storages in most of catchments, especially in western parts of Czechia. However, a lot of regional differences exists and no trends in SWE were detected in some catchments. Decreasing trends in snow cover duration were detected as well, mostly because of earlier snowmelt onset and melt-out.

How to cite: Nedelcev, O. and Jenicek, M.: Changes in seasonal snowpack in mountain catchments in Czechia , EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-9999, https://doi.org/10.5194/egusphere-egu2020-9999, 2020.

EGU2020-10994 | Displays | HS2.1.2

Wind effects on the spatial distribution of snow and seasonal water balance in two Mediterranean basins

Fabiola Pinto Escobar, Pablo A. Mendoza, Thomas E. Shaw, Jesús Revuelto, Keith Musselman, and James McPhee

Snow water equivalent is highly heterogeneous due to the spatial distribution of precipitation, local topographic characteristics, effects of vegetation, and wind. In particular, the latter has important effects on such distribution, controlling the preferential deposition of snowfall, transport (either by saltation or suspension) on the ground, and sublimation of blowing snow. In this work, we analyze the effects of incorporating redistribution by wind transport when modeling the seasonal water balance in two experimental catchments: (i) the Izas catchment (0.33 km²), located in the Spanish Pyrenees, with an elevation range of 2000-2300 m a.s.l., and (ii) Las Bayas catchment (2.45 km²), located in the extratropical Andes Cordillera (Chile) and elevation between 3400 and 3900 m a.s.l. After assessing model simulations using time series of snow depth and terrestrial lidar scans, we examine the water balance at the annual and seasonal scales, quantifying the different fluxes that govern snow accumulation and melting with a spatially distributed model that considers the physics of transport and the sublimation of blowing snow. Moreover, we characterize the sensitivity of dominant processes to changes in precipitation and temperature. The results of this investigation have important implications on current and future research, allowing to contrast wind effects in the spatio-temporal patterns of accumulation and melting in alpine and subalpine areas, identifying those processes that will be most affected under projected climatic conditions.

How to cite: Pinto Escobar, F., Mendoza, P. A., Shaw, T. E., Revuelto, J., Musselman, K., and McPhee, J.: Wind effects on the spatial distribution of snow and seasonal water balance in two Mediterranean basins, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-10994, https://doi.org/10.5194/egusphere-egu2020-10994, 2020.

EGU2020-11810 | Displays | HS2.1.2

Investigating global changes in snow dynamics and the impact on water resources

Adrià Fontrodona Bach, Joshua Larsen, Ross Woods, Bettina Schaefli, and Ryan Teuling

Snow is a key component of the hydrological cycle in many regions of the world, providing a natural storage of water by accumulating snow in winter and releasing it in spring. Many ecosystems, societies and economies rely on this mechanism as a water resource. There is strong evidence in the literature that global warming leads to decreasing snowfall and snow accumulation and shifts the onset of the melt season to earlier in the year. However, little is known about how rising temperatures affect snowmelt rates and timing, and how these can have an impact on water resources for instance by changing the time and magnitude of streamflow. Some studies predict slower snowmelt rates in a warmer world, due to the onset of melt being earlier when there is less energy available for melt, but there is not yet an observation-based study showing such trends. As a first step, here we present preliminary results of observed long term trends in snowmelt rates from different climates. We use a dataset that has already shown strong decreasing signals for winter snow accumulation. Here we also present potential avenues to investigate the sensitivity of snowpacks and snowmelt regimes in different climatic settings to further rising temperatures using modeled snow dynamics. A few possibilities on how to link the snowpack dynamics to impacts in water resources are also discussed, for instance by comparing modelled dynamics to hydrological models and observations.

How to cite: Fontrodona Bach, A., Larsen, J., Woods, R., Schaefli, B., and Teuling, R.: Investigating global changes in snow dynamics and the impact on water resources, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-11810, https://doi.org/10.5194/egusphere-egu2020-11810, 2020.

EGU2020-11298 | Displays | HS2.1.2

Snow Water Equivalents exclusively from Snow Heights and their temporal Change: The ΔSNOW.MODEL

Michael Winkler and Harald Schellander

Snow heights have been measured at lots of places over many years and decades, often at daily resolution. In many cases the data series have no gaps and are of high quality. In recent times, remote sensing provides more and more maps of snow heights, sometimes at high temporal frequency as well. However, most of these snow height data series lack information about snow water equivalents (SWEs), and they often come without sufficient meteorological data to run sophisticated, process-based snow models to simulate SWEs. Statistical SWE models, on the other hand, are subject to regional calibration parameters and cannot model SWEs of distinct days. Nevertheless, for many applications (hydrology, climatology, structural design,…) SWE-series are very valuable.

The ΔSNOW.MODEL presented, is a semi-empirical layer-model that simulates SWEs exclusively from snow heights and their temporal changes. It is computationally cheap and is provided as an easy-to-use R-package. Like statistical snow models, the ΔSNOW.MODEL does not need any meteorological input, but simulates more accurate SWE values: Statistical models typically show root mean square differences between observations and model values of 20-50 kg/m², biases of maximum seasonal SWE of +50 to +100 kg/m², and timing offsets for seasonal maximum SWE of -15 to 0 days. The ΔSNOW.MODEL reaches 15-30 kg/m², -20 to +20 kg/m², and -3 to +5 days, respectively. These scores are comparable with those of process based models, though they are calculated without the need of further meteorological or geographical data except snow height. Therefore, the ΔSNOW.MODEL can be used to assign highly reliable means and maxima of SWE as well as durations of high snow loads to long-term and historic snow height data, and it can simulate SWEs of distinct days with a comparatively high precision. In some (promising) respect the ΔSNOW.MODEL bridges the gap between process-based and statistical snow models.

How to cite: Winkler, M. and Schellander, H.: Snow Water Equivalents exclusively from Snow Heights and their temporal Change: The ΔSNOW.MODEL, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-11298, https://doi.org/10.5194/egusphere-egu2020-11298, 2020.

Spatio-temporal variation of snowmelt affects the Earth’s radiation budget hence serves as a proxy of climate change and global warming. Ablation zone including blue ice and wetsnow has a low surface albedo and melt water ponding ice shelf surface during summer that enhances crevasse propagation then poses a threat the stability of ice shelves. The lack of high spatial and temporal ablation product limits the in-depth exploration of the mechanism and spatio-temporal characteristics of ablation in Antarctica. Here an ablation area detection method based on the modified normalized difference water index adapted for ice (MNDWIice ) is developed to determine and characterize ablation variationsbased on Landsat-8 images of the Dalk glacier, East Antarctica, between September 2016 and March 2017.. The results showed that the Landsat-8 reflectance data can be used to extract seasonal ablation using a uniform MNDWIice threshold (0.136), and the average extraction accuracy is 81.5%, and varies between 67.7% and 94.2% in case of the thin cloud and fractional topographic shadow.The ablation area and the mean value of MNDWIice in the ablation zone show obvious seasonal spatio-temporal variation characteristics. The ablation area in the Dalk glacier appears no later than the earliest time (early September) of the observation. The earliest appearance of ablation is mainly distributed at the eastern grounding line where the terrain changes drastically. Brightness temperature and air temperature of Zhongshan Station show a strong correlation, which can be used as a mechanism analysis of the ablation zone distribution.

Key words Antarctica, Dalk glacier, ablation, MNDWIice

How to cite: Qu, Y. and Liu, Y.: Extraction of seasonal surface ablation zone in DALK glacier based on Landsat-8, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-13049, https://doi.org/10.5194/egusphere-egu2020-13049, 2020.

EGU2020-11985 | Displays | HS2.1.2

Calibration of a semi-distributed hydrological model adding constrains from remotely sensed snow cover and soil moisture products

Rui Tong, Juraj Parajka, Jürgen Komma, and Günter Blöschl

Remote sensing products have been widely applied in hydrological modeling for more realistic representations of hydrological processes. In this study, in addition to gauged discharge, the combined MODIS snow cover maps and ERS scatterometer based soil moisture products were added to constrain a semi-distributed conceptual hydrological model. The latest version of MODIS snow cover images provides a daily Normalized Difference Snow Index (NDSI) in a 500-meter resolution. We derived the snow cover maps by using a new NDSI thresholding method from the MODIS Aqua (MYD10A1) and Terra (MOD10A1) daily snow cover products. Furthermore, the newest ERS soil moisture product also provided a finer spatial resolution of 500-meter over Austria. The semi-distributed TUW-model was tested in 213 catchments using both single and multiple object calibration methods. We found that the semi-distributed TUW-model performed well in discharge modeling. Moreover, applying the MODIS snow cover maps improved the accuracy in the snow-melt season, while the soil moisture product helped the discharge simulation in the no-snow period.

How to cite: Tong, R., Parajka, J., Komma, J., and Blöschl, G.: Calibration of a semi-distributed hydrological model adding constrains from remotely sensed snow cover and soil moisture products, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-11985, https://doi.org/10.5194/egusphere-egu2020-11985, 2020.

Seasonal snowpack significantly influences the catchment runoff and thus represents an important input for the hydrological cycle. Changes in the precipitation distribution and intensity, as well as a shift from snowfall to rain is expected in the future due to climate changes. As a result, rain-on-snow events, which are considered to be one of the main causes of floods in winter and spring, may occur more frequently.

The objective of this study is 1) to evaluate the frequency, inter-annual variability and extremity of rain-on-snow events in the past based on existing measurements and 2) to simulate the effect of predicted increase in air temperature on the occurrence of rain-on-snow events in the future. We selected 59 near-natural mountain catchments in Czechia with significant snow influence on runoff and with available long-time series (>35 years) of daily hydrological and meteorological variables. A semi-distributed conceptual model, HBV-light, was used to simulate the individual components of the water cycle at a catchment scale. The model was calibrated for each of study catchments by using 100 calibration trials which resulted in respective number of optimized parameter sets. The model performance was evaluated against observed runoff and snow water equivalent. Rain-on-snow events definition by threshold values for air temperature, snow depth, rain intensity and snow water equivalent decrease allowed us to analyze inter-annual variations and trends in rain-on-snow events during the study period 1980-2014 and to explain the role of different catchment attributes.

The preliminary results show that a significant change of rain-on-snow events related to increasing air temperature is not clearly evident. Since both air temperature and elevation seem to be an important rain-on-snow drivers, there is an increasing rain-on-snow events occurrence during winter season due to a decrease in snowfall fraction. In contrast, a decrease in total number of events was observed due to the shortening of the period with existing snow cover on the ground. Modelling approach also opened further questions related to model structure and parameterization, specifically how individual model procedures and parameters represent the real natural processes. To understand potential model artefacts might be important when using HBV or similar bucket-type models for impact studies, such as modelling the impact of climate change on catchment runoff.

How to cite: Hotovy, O. and Jenicek, M.: Changes in snow storages and their impact on occurrence and extremity of runoff caused by rain-on-snow events, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-13431, https://doi.org/10.5194/egusphere-egu2020-13431, 2020.

EGU2020-13804 | Displays | HS2.1.2

regionalization of the potential to increase rainfall-runoff model performance by multi-objective calibration using modis data over Austria

Martin Kubáň, Patrik Sleziak, Adam Brziak, Kamila Hlavčová, and Ján Szolgay

A multi-objective calibration of the parameters of conceptual hydrologic models has the potential to improve the consistency of the simulated model states, their representativeness with respect to catchment states and thereby to reduce the uncertainty in the estimation of hydrological model outputs. Observed in-situ or remotely sensed state variables, such as the snow cover distribution, snow depth, snow water equivalent and soil moisture were often considered as additional information in such calibration strategies and subsequently utilized in data assimilation for operational streamflow forecasting. The objective of this paper is to assess the effects of the inclusion of MODIS products characterizing soil moisture and the snow water equivalent in a multi-objective calibration strategy of an HBV type conceptual hydrological model under the highly variable physiographic conditions over the whole territory of Austria.

The methodology was tested using the Technical University of Vienna semi-distributed rainfall-runoff model (the TUW model), which was calibrated and validated in 213 Austrian catchments. For calibration we use measured data from the period 2005 to 2014. Subsequently, we simulated discharges, soil moisture and snow water equivalents based on parameters from the multi-objective calibration and compared these with the respective MODIS values. In general, the multi-objective calibration improved model performance when compared to results of model parametrisation calibrated only on discharge time series. Sensitivity analyses indicate that the magnitude of the model efficiency is regionally sensitive to the choice of the additional calibration variables. In the analysis of the results we indicate ranges how and where the runoff, soil moisture and snow water equivalent simulation efficiencies were sensitive to different setups of the multi-objective calibration strategy over the whole territory of Austria. It was attempted to regionalize the potential to increase of the overall model performance and the improvement in the consistency of the simulation of the two-state variables. Such regionalization may serve model users in the selection which remotely sensed variable or their combination is to be preferred in local modelling studies.

How to cite: Kubáň, M., Sleziak, P., Brziak, A., Hlavčová, K., and Szolgay, J.: regionalization of the potential to increase rainfall-runoff model performance by multi-objective calibration using modis data over Austria, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-13804, https://doi.org/10.5194/egusphere-egu2020-13804, 2020.

EGU2020-19027 | Displays | HS2.1.2

Small-scale processes with large-scale impacts: Investigating canopy structure controls on energy fluxes to the forest snowpack

Giulia Mazzotti, Richard Essery, Johanna Malle, Clare Webster, and Tobias Jonas

Forest canopies strongly affect snowpack energetics during wintertime. In discontinuous forest stands, spatio-temporal variations in radiative and turbulent fluxes create complex snow distribution and melt patterns, with further impacts on the hydrological regimes and on the land surface properties of seasonally snow-covered forested environments.

As increasingly detailed canopy structure datasets are becoming available, canopy-induced energy exchange processes can be explicitly represented in high-resolution snow models. We applied the modelling framework FSM2 to obtain spatially distributed simulations of the forest snowpack in subalpine and boreal forest stands at high spatial (2m) and temporal (10min) resolution. Modelled sub-canopy radiative and turbulent fluxes were compared to detailed meteorological data of incoming irradiances, air and snow surface temperatures. These were acquired with novel observational systems, including 1) a motorized cable car setup recording spatially and temporally resolved data along a transect and 2) a handheld setup designed to capture temporal snapshots of 2D spatial distributions across forest discontinuities.

The combination of high-resolution modelling and multi-dimensional datasets allowed us to assess model performance at the level of individual energy balance components, under various meteorological conditions and across canopy density gradients. We showed which canopy representation strategies within FSM2 best succeeded in reproducing snowpack energy transfer dynamics in discontinuous forests, and derived implications for implementing forest snow processes in coarser-resolution models.

How to cite: Mazzotti, G., Essery, R., Malle, J., Webster, C., and Jonas, T.: Small-scale processes with large-scale impacts: Investigating canopy structure controls on energy fluxes to the forest snowpack , EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-19027, https://doi.org/10.5194/egusphere-egu2020-19027, 2020.

EGU2020-19549 | Displays | HS2.1.2

Historical Relationship between Snow Depth and Damaged Area in South Korea

Gunhui Chung and Heeseong Park

Recently, snow disasters have been increased in South Korea due to the unexpected heavy snow in a region where winter gives little snow. For instance, 10 people were dead by the collapsed roof due to the unusual heavy snow. Many local governments do not have enough snow removal equipment because of little snow in winter season. Therefore, it has been important to estimate the amount of snow damage to prepare heavy snow disaster. There are not many researches to estimate damage of snow disaster in South Korea. In this study, historical snow damage data from 1994~2018 recorded in National Disaster Report were used to predict the future snow disaster damage using a statistical equation. However, it was not easy to predict the amount of snow damage when the heavy snow is happened in the area where no snow during the winter in history. Therefore, the relationship between the snow depth and damaged area were analyzed using the historical damage data. Principal multiple regression method was applied to develop the snow damage estimation function using the damaged area. The developed model could be applied to plan the budget for the snow removal equipment or snow damage reduction.

 

Acknowledgement:

This work was supported by Korea Environment Industry & Technology Institute (KEITI) through Intelligent Management Program for Urban Water Resources Project, funded by Korea Ministry of Environment(MOE) (2019002950002).

 

How to cite: Chung, G. and Park, H.: Historical Relationship between Snow Depth and Damaged Area in South Korea, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-19549, https://doi.org/10.5194/egusphere-egu2020-19549, 2020.

EGU2020-19825 | Displays | HS2.1.2

PRISMA hyperspectral satellite mission: first data on snow in the Alps

Biagio Di Mauro, Roberto Garzonio, Gabriele Bramati, Sergio Cogliati, Edoardo Cremonese, Tommaso Julitta, Cinzia Panigada, Micol Rossini, and Roberto Colombo

On the 22nd of March 2019, PRISMA (PRecursore IperSpettrale della Missione Applicativa) mission has been launched by the Italian Space Agency (ASI). Since then, the spacecraft has been collecting on demand hyperspectral data of the Earth surface. The imaging spectrometer features 239 bands covering the visible, near infrared and shortwave infrared wavelengths (400-2500 nm) with a spectral resolution <12nm. PRISMA acquires hyperspectral images with a spatial resolution of 30m and a swath of 30 km.

The satellite mission is still in the initial commissioning phase. During this period, the acquisition of field spectroscopy data contemporary to satellite observation is fundamental. With the aim of calibrating and validating PRISMA observations on snow fields, we organized field campaigns at a high altitude (2160 m) experimental site (Torgnon, Aosta Valley) in the European Alps. During these campaigns, we measured spectral reflectance of snow with a Spectral Evolution spectrometer (350-2500 nm), snow grain size, and snow density. Among different instruments operating at the site (e.g. net radiometer, webcam, sensors for snow depth, snow water equivalent, snow surface temperature etc.), we recently installed an unattended spectrometer acquiring continuous measurements of snow reflectance. This instrument covers part of the visible and near infrared spectral range (400-900 nm) and it was used to analyze the daily evolution of snow reflectance during the snow season.

In this contribution, we present a preliminary comparison between field and satellite hyperspectral reflectance data of snow. This comparison is fundamental for the future development of algorithms for the estimation of snow physical variables (snow grain size, snow albedo, and concentration of impurities) from satellite hyperspectral data.

How to cite: Di Mauro, B., Garzonio, R., Bramati, G., Cogliati, S., Cremonese, E., Julitta, T., Panigada, C., Rossini, M., and Colombo, R.: PRISMA hyperspectral satellite mission: first data on snow in the Alps, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-19825, https://doi.org/10.5194/egusphere-egu2020-19825, 2020.

EGU2020-20004 | Displays | HS2.1.2

Combined use of geostatistical and conceptual hydrological models for a preliminary assessment of “undercatch” of precipitation in The Canales Basin (Sierra Nevada, Spain).

Patricia Jimeno-Sáez, Antonio Juan Collados-Lara, Rodolfo Alvarado-Montero, David Pulido-Velazquez, Eulogio Pardo-Igúzquiza, and Javier Senent-Aparicio

Gauges modify wind fields, producing important undercatch in solid precipitation.  For this reason, solid precipitation measurements show significant bias with respect to real values, especially under windy conditions. In this work we propose a methodology that combines geostatistical and hydrological models to perform a preliminary assessment of global undercatch and precipitation patterns (distribution between solid and liquid phase and spatial gradient with elevation) in alpine regions. It is based on the available information about daily natural streamflow and daily climatic data (precipitation and temperature) in the catchment. We want to analyse long time periods in order to take into account the stochastic behaviour of natural streamflow and climatic variables. A preliminary assessment of temperature and precipitation fields is performed by applying various geostatistical approaches assuming some hypothesis about the relationship between climatic fields and altitude. The generated fields are then employed as inputs of conceptual hydrological models, which includes two parameters to correct the solid and liquid precipitation, respectively. We have considered different hydrological approaches (SRM, HBV and a Témez model with a simple degree-day approach). The parameters are calibrated by minimizing the difference between the simulated and historical natural streamflows and/or snow cover area. It allows us to identify the best combination of geostatistical and hydrological models to approximate streamflow, to perform a global preliminary assessment of the undercatch of solid and liquid precipitation and their precipitation patterns by analysing spatial gradients with elevation. The methodology was applied in the Canales Basin, an alpine catchment of the Sierra Nevada (Spain).

This research has been partially supported by the SIGLO-AN project (RTI2018-101397-B-I00) from the Spanish Ministry of Science, Innovation and Universities (Programa Estatal de I+D+I orientada a los Retos de la Sociedad) and by the GeoE.171.008-TACTIC project from GeoERA organization funded by European Union’s Horizon 2020 research and innovation program

How to cite: Jimeno-Sáez, P., Collados-Lara, A. J., Alvarado-Montero, R., Pulido-Velazquez, D., Pardo-Igúzquiza, E., and Senent-Aparicio, J.: Combined use of geostatistical and conceptual hydrological models for a preliminary assessment of “undercatch” of precipitation in The Canales Basin (Sierra Nevada, Spain). , EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-20004, https://doi.org/10.5194/egusphere-egu2020-20004, 2020.

EGU2020-21463 | Displays | HS2.1.2

The impact of glaciers on the long-term hydrology of a high-elevation Andean catchment

Michael McCarthy, Flavia Burger, Alvaro Ayala, Stefan Fugger, Thomas E Shaw, Evan Miles, Shelley MacDonell, Atanu Bhattacharya, Tobias Bolch, James McPhee, and Francesca Pellicciotti

The Andean cryosphere is a vital water resource for downstream populations. In recent years, it has been in steep decline as a whole, but shown strong spatio-temporal variability due to climatic events such as the current mega drought in central Chile. Glacio-hydrological models are necessary to understand and predict changes in water availability as a result of changes to the cryosphere. However, due to a lack of data for initialisation, forcing, calibration and validation, they are rarely used, especially in the Andes, for periods longer than a few years or decades. While useful insights can be gained from short-term modelling, there is a gap in our understanding of how glaciers impact hydrology on longer timescales, which may prevent local communities and governments from achieving effective planning and mitigation. Here we use the glacio-hydrological model TOPKAPI-ETH – initialised, forced, calibrated and validated using unique and extensive field and remote sensing datasets – to investigate glacier contributions to the streamflow of the high-elevation Rio Yeso catchment, Chile, over the past 50 years. We focus in particular on: 1) fluctuations in glacier surface mass balance and runoff and associated climatic variability; 2) if peak water has already occurred and when; 3) the effect of supraglacial debris cover on seasonal and long-term hydrographs. We offer insights into some of the challenges of running glacio-hydrological models on longer timescales and discuss the implications of our findings in the context of a shrinking Andean cryosphere.

How to cite: McCarthy, M., Burger, F., Ayala, A., Fugger, S., Shaw, T. E., Miles, E., MacDonell, S., Bhattacharya, A., Bolch, T., McPhee, J., and Pellicciotti, F.: The impact of glaciers on the long-term hydrology of a high-elevation Andean catchment, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-21463, https://doi.org/10.5194/egusphere-egu2020-21463, 2020.

EGU2020-21740 | Displays | HS2.1.2

Modeling spatial snow-cover distribution using snow-melt models and MODIS images

Dhiraj Raj Gyawali and András Bárdossy

Reliable representations of spatial distribution of snow and subsequent snow-melt are critical challenges for hydrological estimations, given their crucial relevance in mountainous regimes especially because of the high sensitivity to climate change. Relatively accurate physically based models are data intensive while in-situ measurements of snow-depth are prone to be non-representative due to local influences. Likewise, lack of snow-depth information and to some extent, cloud cover in the mountains limit the usage of Remote-sensing images in snow estimation. Against this backdrop, this work presents a methodology incorporating available remotely-sensed images (MODIS Snow-cover products) and simple distributed snow-melt models to estimate a time-continuous spatial snow extent in snow dominated regimes. 

The methodology employs relatively cloud-free MODIS composite images to calibrate the spatial distribution of snow simulated by different distributed degree-day models. These variants of models are run in a domain of 500m x 500m grids, and incorporate daily precipitation, daily min-, max- and mean temperatures, and daily radiation data interpolated onto the aforementioned grids. Variations in the models include a simple degree model followed by incorporation of different aspects governing snow hydrology such as precipitation induced melt, radiation, topography, and land use.  The modeled snow depths in each grid are reclassified to ‘1’ (snow depths above a threshold) and ‘0’ (no snow), and calibrated against MODIS snow-cover for cloud-free days with snow. Snow-melt parameters are then estimated for the region of interest. The result is a spatial snow-cover distribution time-series. This approach is replicated in different regions viz. Baden-Württemberg and Bavaria in Germany, and in Switzerland. Results suggest good agreement with MODIS data and the parameters show relative stability across the time domain at the same sites and are transferrable to other regions. Calibration using readily available images used in this method offers adequate flexibility, albeit the simplicity, to calibrate snow distribution in mountainous areas across a wide geographical extent with reasonably accurate precipitation and temperature data. The final validated spatial snow-distribution data can be, as a stand-alone input, coupled with distributed hydrological models to reliably estimate streamflow in data-scarce mountainous catchments.

How to cite: Gyawali, D. R. and Bárdossy, A.: Modeling spatial snow-cover distribution using snow-melt models and MODIS images, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-21740, https://doi.org/10.5194/egusphere-egu2020-21740, 2020.

EGU2020-21946 | Displays | HS2.1.2

On the computation of phase inconsistencies of Sentinel-1 interferograms over snow-covered areas

Maria Gritsevich, Giovanni Nico, Vasco Conde, Pedro Mateus, and Joao Catalao

We have recently investigated the use of SAR interferometry for the mapping of Snow Water Equivalent (SWE) temporal variations using Sentinel-1 data [1]. Maps of temporal changes of SWE, measured with a sub-centimetre accuracy and updated every six days have been obtained over a study area in Finland. This methodology relies on the shift in the interferometric phase caused by the refraction of the microwave signal penetrating the snow layer. In this work, we investigate phase inconsistencies [2] of a sets of three interferograms obtained from three Sentinel-1 images acquired along the same orbit at different acquisition times to study the snow melt. We find that while phase inconsistencies are not expected to be present in case of examining surfaces covered with frozen snow, the scattering mechanism of microwave in the snow layer during the melting phase affects both the interferometric phase and coherence.

 

This work was supported, in part, by the Academy of Finland project no. 325806.

 

References:

[1] V. Conde, G. Nico, P. Mateus, J. Catalão, A. Kontu, M. Gritsevich, On the estimation of temporal changes of snow water equivalent by spaceborne SAR interferometry: a new application for the Sentinel-1 mission, J. Hydrol. Hydromech., 67, 2019, 1, 93–100. DOI: 10.2478/johh-2018-0003

[2] F. De Zan, M. Zonno, P. López-Dekker, Phase inconsistencies and multiple scattering in SAR interferometry, IEEE Transactions on Geoscience and Remote Sensing, 53(12), 6608-6616, 2015

How to cite: Gritsevich, M., Nico, G., Conde, V., Mateus, P., and Catalao, J.: On the computation of phase inconsistencies of Sentinel-1 interferograms over snow-covered areas, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-21946, https://doi.org/10.5194/egusphere-egu2020-21946, 2020.

EGU2020-21774 | Displays | HS2.1.2

Remote sensing of snow and atmosphere properties using Ocean and Land Colour Instrument on board Copernicus Sentinel-3 mission

Alexander Kokhanovsky, Jason Box, Baptiste Vandecrux, and Michael Kern

In this work we propose a simple technique to derive snow and atmosphere properties from satellite top-of-atmosphere spectral reflectance observations using asymptotic radiative transfer theory valid for the case of weakly absorbing and optically thick media. The following snow properties are derived and analyzed: ice grain size, snow specific surface area, snow pollution load, snow spectral and broadband albedo. The developed retrieval technique includes both atmospheric correction and cloud screening routines and is based on Ocean and Land Colour Instrument (OLCI) measurements on board Sentinel-3A, B. The spectral aerosol optical thickness, total ozone and water vapour column are derived fitting the measured and simulated OLCI-registered spectral reflectances at 21 OLCI channels.

The derived results are validated using ground - based observations. It follows that satellite observations can be used to study time series of spectral and broadband albedo over Greenland. The deviations of satellite and ground observations are due to problems with cloud screening over snow and also due to different spatial scale of satellite and ground observations (Kokhanovsky et al., 2020).

Acknowledgements

The work has been supported by the European Space Agency in the framework of ESRIN contract No. 4000118926/16/I-NB ‘Scientific Exploitation of Operational Missions (SEOM) Sentinel-3 Snow (Sentinel-3 for Science, Land Study 1: Snow’) and ESRIN contract 4000125043 – ESA/AO/1-9101/17/I-NB EO science for society ‘Pre-operational Sentinel-3 snow and ice products’.

References

Kokhanovsky, A.A., et al. (2020), The determination of snow albedo from satellite observations using fast atmospheric correction technique, Remote Sensing, 12 (2), 234,  https://doi.org/10.3390/rs12020234.

How to cite: Kokhanovsky, A., Box, J., Vandecrux, B., and Kern, M.: Remote sensing of snow and atmosphere properties using Ocean and Land Colour Instrument on board Copernicus Sentinel-3 mission, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-21774, https://doi.org/10.5194/egusphere-egu2020-21774, 2020.

EGU2020-15035 | Displays | HS2.1.2

Attribution of basin-wide snowline dynamics to climate variations in the Pskem River basin, Central Asia

Abror Gafurov, Adkham Mamaraimov, and Uktam Adkhamov

EGU2020-20038 | Displays | HS2.1.2

Baseflow separation methods in snowfed rivers in Mediterranean catchments: a process-oriented assessment for hydrograph analysis

Pedro Torralbo, Rafael Pimentel, María José Pérez-Palazón, Javier Aparicio, Javier Herrero, Cristina Aguilar, and María José Polo

Water storage availability of semiarid regions is closely linked to the snow reservoir and its changes. The change of hydrological regime in mountain rivers is strongly affected by the snowpack’s dynamics, which plays a crucial role during spring and/or summer season in Mediterranean areas, becoming one of the major water sources to streamflow. This influence can be analyzed from different approaches; however, due to the concurrence of different processes, whose interaction and propagation undoubtedly affect runoff and baseflow generation, a process-oriented approach is required for further understanding the ultimate reasons behind the observed changes. Hence, the partitioning of river flow into baseflow, subsurface flown, and runoff, is a key step in hydrograph analysis and for better understanding snowfed rivers and how climate variability can influence their regime.

This work presents an assessment of different baseflow separation methods in mountain rivers of semiarid areas in the framework of a process-oriented approach for identifying the major sources/sinks of water. The study area comprises the headwaters of the different basins in the Sierra Nevada area, in southern Spain, within an altitudinal range of 1000-3479 m a.s.l., high slopes, and different facing. For this, a 20-yr series of daily flow in a gauged point in the Guadalfeo River that drains the southwestern area of Sierra Nevada is analyzed. Five standard baseflow separation methods, together with the simulation by the physically-based hydrological model WiMMed, which includes the module SNOWMED developed from an energy-water balance approach and validated in the study site, were selected and their results compared. Discussion on the effects of the final baseflow series on the descriptors of the direct-runoff hydrograph (daily time step) series is also included, considering snowmelt- and rainfall-driven events, and their combination.

The results not only provide a better understanding of baseflow separation in snowfed rivers in semiarid regions, but also assess hydrograph analysis in a process-oriented approach.  

How to cite: Torralbo, P., Pimentel, R., Pérez-Palazón, M. J., Aparicio, J., Herrero, J., Aguilar, C., and Polo, M. J.: Baseflow separation methods in snowfed rivers in Mediterranean catchments: a process-oriented assessment for hydrograph analysis, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-20038, https://doi.org/10.5194/egusphere-egu2020-20038, 2020.

Glacier-wide mass balances and catchment-wide runoffs are reconstructed over 1979-2018 for Dokriani Glacier catchment in the Garhwal Himalaya (India). A glacio-hydrological model including temperature-index, accumulation, rain and evapotranspiration modules is used for the reconstruction using daily air-temperature and precipitation fields from ERA5 data. Model is calibrated using 6 years of observed annual glacier-wide mass balances (1993-1995 and 1998-2000) and observed summer mean monthly runoff (1994, 1998-2000) data. Modelled mass wastage on Dokriani Glacier is moderate with annual loss of −0.28±0.38 m w.e. a–1 over 1979-2018. The mean winter glacier-wide mass balance is 0.62±0.38 m w.e. a–1 while mean summer glacier-wide mass balance is −0.91±0.38 m w.e. a–1 over 1979-2018. The mean annual catchment-wide runoff is 1.38±0.11 m3 s–1 over 1979-2018. Maximum runoff is produced during summer-monsoon months with a peak in August (5.35 m3 s−1). Rainfall contributes the maximum to the total mean annual runoff with 44% share while snow melt and ice melt contribute 35% and 22%, respectively. The loss through evapotranspiration is only around 2% of the total runoff. The heterogeneous debris-cover distribution over lower ablation area (<5000 m a.s.l.) protects the glacier for higher melting. Decadal mass balances suggest that Dokriani Glacier was close to steady-state conditions over 1989-1997 because of negative temperature anomaly and positive precipitation anomaly over this period. Mass balance and runoff are the most sensitive for threshold temperature for melt with sensitivities of −0.71 m w.e. a–1oC–1 and 0.18 m3 s–1 oC–1, respectively.

How to cite: Azam, M. F. and Srivastava, S.: Glacio-hydrological modelling of partially debris-covered Dokriani Glacier in monsoon-dominated Garhwal Himalaya (India), EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-2060, https://doi.org/10.5194/egusphere-egu2020-2060, 2020.

EGU2020-2123 | Displays | HS2.1.2

Case Study of Blowing Snow Potential Diagnosis with Dynamical Downscaling

Seika Tanji and Masaru Inatsu

Blowing snow potential is diagnosed for typical cases in roads around Sapporo, Japan, as snow concentration and visibility based on dynamically downscaled data with 1-km resolution. The results are consistent with the blowing-snow records on time and place of traffic disruption, when the dynamical downscaling (DDS) reproduced wind speed well for a case. Moreover, the DDS-based diagnosis had a strength on the onset and cease of blowing snow in the event. The diagnosis with mesoscale model analysis with 5-km resolution does not reproduce the blowing snow events in most area, however. Hence, the DDS potentially, not perfectly, adds the value to estimate blowing snow potential, despite a large scale-gap from an explicit representation of small-scale turbulence related to blowing snow. The meteorological forecast with 1-km resolution might improve the estimate of blowing snow potential.

How to cite: Tanji, S. and Inatsu, M.: Case Study of Blowing Snow Potential Diagnosis with Dynamical Downscaling, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-2123, https://doi.org/10.5194/egusphere-egu2020-2123, 2020.

EGU2020-13636 | Displays | HS2.1.2

Assessing impacts of future potential climate change scenarios on snow cover area by using cellular automata models and Montecarlo simulations

David Pulido-Velazquez, Antonio-Juan Collados-Lara, and Eulogio Pardo-Igúzquiza

Climate change will modify the availability of snow resources in the future. Thus developing methodologies to assess impacts of potential future climate change scenarios on snow variables is a key subject. In this work we combine several previous developed methodologies (downscaling climate change scenarios to local scale, cellular automata models, and stochastic weather generators) to assess impacts of future climate change scenarios and its uncertainty on snow cover area through a Montecarlo simulation. The cellular automata model uses climatic indices (precipitation and temperature) as driving variables to estimate snow cover area. Future scenarios of these variables can be generated using bias correction and delta change approaches and different regional climate models. The stochastic weather generators allow us to produce multiple series of precipitation and temperature based on the statistical characteristics of the future local scenarios generated. These multiple series can be used as inputs of the cellular automata model in order to assess the future snow cover area and its uncertainty. The main advantages of the proposed methodology are its applicability in cases with limited information and in mountain ranges scales. The methodology has been applied to the Sierra Nevada mountain range in southern Spain. This area has a Mediterranean climate very sensitive to climate change. Using the future precipitation and temperature scenarios generated considering the Representative Concentration Pathways 8.5 (RCP8.5) for the period 2071–2100, we obtain a significant reduction in snow cover area, with mean values of 59.0% for the local scenarios generated with a delta change approach, and 61.7% for those one generated with the bias correction approach.

This research has been partially supported by the SIGLO-AN project (RTI2018-101397-B-I00) from the Spanish Ministry of Science, Innovation and Universities (Programa Estatal de I+D+I orientada a los Retos de la Sociedad).

How to cite: Pulido-Velazquez, D., Collados-Lara, A.-J., and Pardo-Igúzquiza, E.: Assessing impacts of future potential climate change scenarios on snow cover area by using cellular automata models and Montecarlo simulations, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-13636, https://doi.org/10.5194/egusphere-egu2020-13636, 2020.

HS2.1.3 – Changes in the Mediterranean hydrology: observation and modeling

EGU2020-7162 * | Displays | HS2.1.3 | Highlight

Climate change impacts on water resources in North African basins

Yves Tramblay, Denis Ruelland, Lahoucine Hanich, Zoubeida Bargaoui, and Hammouda Dakhlaoui

Countries in North Africa are facing water scarcity and a high inter-annual variability of precipitation. In this context, many dams have been built to collect surface water and improve the management of existing water resources. We present the main results of a recent MISTRALS-ENVIMED research project about the potential climate change impacts on water resources at the regional and basin scales. The project notably focuses on the uncertainties linked to the different components of the modelling chain required to produce hydrological scenarios. Climate change impacts on surface water resources are investigated using an ensemble of regional climate model simulations from the CORDEX experiment under different emission scenarios and different hydrological models, adapted to the context of data scarcity. Climate scenarios under RCP4.5 and RCP8.5 over North Africa indicate a future decrease in precipitation together with an increase in temperature that could have significant impacts on water resources. Indeed, a future decrease of surface water availability is expected in all major dam catchments, with a stronger decline over Morocco.

How to cite: Tramblay, Y., Ruelland, D., Hanich, L., Bargaoui, Z., and Dakhlaoui, H.: Climate change impacts on water resources in North African basins , EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-7162, https://doi.org/10.5194/egusphere-egu2020-7162, 2020.

EGU2020-13806 | Displays | HS2.1.3 | Highlight

Future changes in hydrological extremes of a Mediterranean catchment: what can we say in an uncertainty context?

Lila Collet, Thibault Lemaitre-Basset, Guillaume Thirel, Juraj Parajka, Guillaume Evin, and Benoît Hingray

The Mediterranean region is a hot spot for climate change impact on the water cycle where water resources are anticipated to decrease and hydrological extremes to intensify while population and water use conflicts growth would keep rising. However, the analysis of the uncertainty related to hydrological projections is generally poorly quantified and difficult to translate to decision-makers. In this study, an in-depth analysis of projections and uncertainties for extreme high- and low-flows was performed. Climatic projections derived from a recent downscaling method over France (Adamont, Verfaillie et al., 2017) were used, and hydrological projections were produced on the Hérault River catchment based on two different Radiative Concentration Pathways (RCPs), five global and regional climate model (GCM/RCM) couples, three hydrological models (HMs), and twenty-nine calibration schemes (Lemaitre-Basset et al., sub). This ensemble was analysed with the QUALYPSO approach (Evin et al., 2019) that allows transient uncertainty analysis of ensembles derived from incomplete GCM/RCM matrix. The quasi-ergodic analysis of variance (QE-ANOVA) used in QUALYPSO evaluates the contribution of each impact modelling step to the total uncertainty. For high-flows, GCMs and RCPs contribute the most to the total uncertainty at the short and long lead-time, respectively. For low-flows, HMs structure and calibration period are the most important sources of uncertainty across 2006-2100. While high-flow projections show a significant mean increase of 30% by 2085 compared to the historical period (confidence intervals: [-1%; +64%]), low-flows would slightly decrease (-7%) by 2085, but with a higher uncertainty (confidence interval: [-24%; +13%]). The time horizons for which a change (e.g. -50, -20, -10, …, +10, +20, +50%) in high- and low-flows intensity becomes robust (i.e. when more than 66% of the ensemble is above/below a given threshold) were also assessed. This provides strong messages to water managers of the Hérault River catchment who can then anticipate the time needed to prepare and adapt to climate change impacts for extreme hydrological hazards.

References:

Evin, G., Hingray, B., Blanchet, J., Eckert, N., Morin, S., & Verfaillie, D. (2019). Partitioning Uncertainty Components of an Incomplete Ensemble of Climate Projections Using Data Augmentation. JOURNAL OF CLIMATE, 32, 18. https://doi.org/10.1175/JCLI-D-18-0606.1

Lemaitre-Basset, T., Collet, L., Thirel, G., Parajka, J., Evin, G., Hingray, B. (submitted) Climate change impact and uncertainty analysis on hydrological extremes in a Mediterranean catchment. Hydrological Sciences Journal

Verfaillie, D., Déqué, M., Morin, S., & Lafaysse, M. (2017). The method ADAMONT v1.0 for statistical adjustment of climate projections applicable to energy balance land surface models. Geoscientific Model Development, 10(11), 4257–4283. https://doi.org/10.5194/gmd-10-4257-2017

How to cite: Collet, L., Lemaitre-Basset, T., Thirel, G., Parajka, J., Evin, G., and Hingray, B.: Future changes in hydrological extremes of a Mediterranean catchment: what can we say in an uncertainty context?, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-13806, https://doi.org/10.5194/egusphere-egu2020-13806, 2020.

EGU2020-9267 | Displays | HS2.1.3

Anthropogenically-induced recharge in a semiarid mountain front context

Houssne Bouimouass, Younes Fakir, Sarah Tweed, and Marc Leblanc

Mountain-fronts constitute important groundwater recharge areas in arid and semiarid regions. Mountain-front recharge processes are generally identified, in natural systems, as streamflow losses and subsurface inflow from the mountain block. However, another key recharge process is from irrigation practices; where mountain streamflow is distributed across the irrigated piedmont. In this study, coupled groundwater fluctuation measurements and stable isotopes (18O and 2H) were used to identify and compare the natural mountain-front recharge to the anthropogenically-induced irrigation recharge. Within the High-Atlas mountain front of the Ourika basin, Tensift, Central Morocco, the groundwater fluctuation mapping from the dry to wet season showed that recharge from irrigation waters was higher than the recharge along the streambed. Irrigation practices in the region divert more than 65% of the stream water, thereby reducing the potential for stream recharge. Due to the traditional irrigation practices, upstream crops are preferentially irrigated with stream water over downstream areas. In downstream areas irrigation is only via stream water during large flood events and is otherwise supplemented by groundwater resources. These changes in water resources used for irrigation practices between upstream and downstream areas are reflected in the spatio-temporal evolution of the stable isotopes of groundwater. In the upstream irrigation area, the groundwater stable isotope values (d18O: -8.4 ‰ to -7.4 ‰) reflect recharge by the diverted stream water. In the downstream irrigation area, the groundwater isotope values are lower (d18O: -8.1 ‰ to -8.4 ‰) due to recharge with floods.

The results from this study particularly highlight that irrigation can deeply modify both the recharge processes and the water balance in the mountain front areas. Groundwater resources in such areas become reliant on the irrigation practices as an important source of recharge, and this anthropogenic modification of the hydrological cycle should be assessed and taken into consideration within climate change impacts and integrated water management strategies.

How to cite: Bouimouass, H., Fakir, Y., Tweed, S., and Leblanc, M.: Anthropogenically-induced recharge in a semiarid mountain front context, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-9267, https://doi.org/10.5194/egusphere-egu2020-9267, 2020.

EGU2020-6957 | Displays | HS2.1.3 | Highlight

The impact of climate change decrease of winter precipitation on the water use efficiency and sustainability of a Mediterranean forest.

Serena Sirigu, Roberto Corona, Nicola Montaldo, Ram Oren, and Dora Soru

Over the past century, climate change has been reflected in altered precipitation regimes worldwide.  Recently, Montaldo and Sarigu (2017) showed that Sardinia runoff decreased over the 1975-2010 period, with mean annual values 40% lower than the 1922-1974 period.

These trends will have dramatic consequences on basin water resources, therefore forests are frequently exposed to periods characterized by a reduced water availability that influences the evapotranspiration process (ET), the water use efficiency and could be also the main cause of tree mortality or change of tree spatial distribution and density.

The Marganai forest, located in South West Sardinia (Italy), is a Long-Term Ecosystem Research (LTER) Italian site and a European Site of Community Importance (Natura 2000) managed by FORESTAS. The vegetation is mainly composed by Quercus Ilex trees and the soil depth varies between 10 cm and 50 cm. Historical data are from 16 rain stations (1922-2018 period) over the entire area and data of runoff of the Fluminimaggiore basin (area of 83 km2) are available. From 1922 a persistent decrease trend of winter precipitation in that area (Mann-Kendall t of -0.26) impacted runoff, which decreased of 2.52 mm/y.

Future climate scenarios are selected from IPCC climate change scenarios. From the 12 Atmosphere-Ocean General Circulation Models (AOGCMs) of Flato et al. (2013), we selected theHadGEM2-AO that simulates reasonable approximation of observed past seasonal precipitation and air temperature changes (1976-2004 compared with 1951-1975) in Sardinia.Using a distributed ecohydrologic model and the HADGEM2-AO future climate (rainfall and air temperature ) scenarios we predict both hydrologic (soil moisture, runoff, ET) and vegetation dynamic (CO2, biomass, leaf area index and vegetation fraction) outputs.

The model has been successfully calibrated for runoff and ET estimation for the 1922 – 2018 period. Then, the eco-hydrological model, forced with the generated future scenarios, predict a significant change on tree leaf area index, with the reduction of tree density, spatial distribution, forest productivity and runoff. Future scenario predicting further decline is particularly alarming for the Marganai forest, requiring new strategies in both forestal and water resources planning and management.

How to cite: Sirigu, S., Corona, R., Montaldo, N., Oren, R., and Soru, D.: The impact of climate change decrease of winter precipitation on the water use efficiency and sustainability of a Mediterranean forest., EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-6957, https://doi.org/10.5194/egusphere-egu2020-6957, 2020.

EGU2020-13665 | Displays | HS2.1.3

OMERE: A Long-Term Observatory of Soil and Water Resources, in Interaction with Agricultural and Land Management in Mediterranean Hilly Catchments

Jérôme Molénat, Damien Raclot, Rim Zitouna, Jean Albergel, and Marc Voltz and the OMERE Team

The hydrology of the Mediterranean region is affected by global changes such as climate and land use changes. In rural areas, changes in farming practices and landscape management can be the main drivers of changes in water cycles and in matter transport associated with hydrological fluxes, such as contaminants and sediments. The process underlying these changes can be slow, such as in land use or contaminant dynamics, or infrequent over time, such as erosion. Understanding these processes and their relationship requires long-term observations to capture slow dynamics or infrequent events. In this context, we present the Mediterranean agro-hydrological observatory OMERE (Mediterranean observatory of the rural environment and water) by explaining the observation strategy and by emphasizing how this strategy and associated research have contributed to a better understanding of the impact of agricultural and land management on mass flows in Mediterranean farmed headwater catchments.

The OMERE observatory is made up of two agricultural catchments, one in the north of Tunisia and the other in the south of France, accounting for for the diversity of agricultural and ecosystem situations in hilly Mediterranean areas. The OMERE observatory belongs to the French national network OZCAR, dedicated to the observation of the critical zone. The observation strategy is motivated by monitoring the flow of water, sediments and contaminants and hydrological and climatic variables at different spatial scales from cultivated plots and landscape elements to the catchment scale. These measurements were made with fine temporal resolution on a long-term scale and examining land use, agricultural practices and soil surface characteristics. The long-term observation strategy aims to support multidisciplinary integrative research to elucidate the conditions that improve soil and water management and the provision of ecosystem services in the Mediterranean context of rain-fed agriculture. The observatory addressed three scientific questions: (i) better understand water flows, erosion and contaminants, in particular pesticides, and their natural and anthropogenic factors in the short and long term; (ii) analyze the overall effects of agriculture and land management on mass flows at different scales, from the plot to the watershed or the landscape; and (iii) develop new scenarios for sustainable agricultural management and better delivery of ecosystem services. Some of the scientific progresses driven by the questions drawn from the OMERE observatory are presented.

Voltz, M., and A. Albergel. 2002. OMERE: Observatoire Méditerranéen de l’Environnement Rural et de l’Eau- Impact des actions anthropiques sur les transferts de masse dans les hydrosystèmes méditerranéens ruraux. Proposition d’Observatoire de Recherche en Environnement. Minist. Français Rech., Paris

Molénat, J., Raclot, D., Zitouna R., ...., Albergel, J., and Voltz M., 2018, OMERE: A Long-Term Observatory of Soil and Water Resources, in Interaction with Agricultural and Land Management in Mediterranean Hilly Catchments, Vadose Zone J., 17:180086. doi:10.2136/vzj2018.04.0086

How to cite: Molénat, J., Raclot, D., Zitouna, R., Albergel, J., and Voltz, M. and the OMERE Team: OMERE: A Long-Term Observatory of Soil and Water Resources, in Interaction with Agricultural and Land Management in Mediterranean Hilly Catchments, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-13665, https://doi.org/10.5194/egusphere-egu2020-13665, 2020.

EGU2020-3100 | Displays | HS2.1.3

Water management and climate change monitoring in Tunisia and Egypt using remote sensing techniques

Simonetta Paloscia, Giacomo Fontanelli, Simone Pettinato, Emanuele Santi, Giuliano Ramat, Emmanuel Da Ponte, Magdy Abdel-Wahab, Yassmina Hesham, Mohamed Ouessar, Hanen Dhaou, Zeineb Kassouk, and Zohra Lili Chabane

This project deals with the implementation of an innovative water management system in Mediterranean countries (i.e. Tunisia and Egypt), which suffer from chronic water scarcity, together with two European countries (Germany and Italy). The consortium is developing and applying synergic methods and algorithms for investigating the water cycle, using remote sensing techniques.

The focus is on the use of satellite data (both optical and microwave) for monitoring vegetation cover and water status along with soil moisture temporal evolutions in order to improve the knowledge of the water cycle in arid areas. Both local and regional monitoring are carried out in order to investigate different spatial scales.

Environmental models and algorithms for the retrieval of hydrological parameters have been developed in the frame of this project in order to match the main goal of the project, i.e. to propose practical and cost-effective solutions for driving and updating a method for the sustainable use of water in agriculture. 

An optimized management of water resources for cultivated lands on Egyptian Delta (Northern part) and Tunisian territory will be realized by analyzing the available spatial and temporal data for the areas of interest appropriately selected for this purpose. As such, an efficient water use, equitable distribution of water resources, community participation in decisions, and sustainable system operation over time can be supported.

First of all, we aim to localize different crop and irrigation techniques for the study regions. This information is required as a basis for further investigations and assessments. Secondly, the water efficiency for different lands, crop types and irrigation systems will be assessed.

Afterwards, possible improvements in agricultural practice with respect to climate change scenarios and information on water efficiency will be determined by rating the outcome from the assessment.

How to cite: Paloscia, S., Fontanelli, G., Pettinato, S., Santi, E., Ramat, G., Da Ponte, E., Abdel-Wahab, M., Hesham, Y., Ouessar, M., Dhaou, H., Kassouk, Z., and Chabane, Z. L.: Water management and climate change monitoring in Tunisia and Egypt using remote sensing techniques, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-3100, https://doi.org/10.5194/egusphere-egu2020-3100, 2020.

EGU2020-7408 | Displays | HS2.1.3

Mapping surface soil moisture over wheat crops in southern Mediterranean regions using the backscattering coefficient and the interferometric coherence derived from Sentinel-1

Nadia Ouaadi, Lionel Jarlan, Jamal Ezzahar, Saïd Khabba, Mehrez Zribi, Elhoussaine Bouras, Safa Bousbih, and Pierre-Louis Frison

High spatial and temporal resolution products of Sentinel-1 are used for surface soil moisture (SSM) mapping over wheat fields in semi-arid areas. Within these regions, monitoring the water-use is a critical aspect for optimizing the management of the limited water resources via irrigation monitoring. SSM is one of the principal quantities affecting microwave remote sensing. This sensitivity has been exploited to estimate SSM from radar data, which has the advantages of providing data independent of illumination and weather conditions. In addition, with the use of Sentinel-1 products, the spatial and temporal resolution is greatly improved. Within this context, the main objective of this work is estimate SSM over wheat fields using an approach based on the use of C-band Sentinel-1 radar data only. Over the study site, field measurement are collected during 2016-2017 and 2017-2018 growing seasons over two fields of winter wheat with drip irrigation located in the Haouz plain in the center of Morocco. Data of other sites in Morocco and Tunisia are taken for validation purposes. The validation database contains a total number of 20 plots divided between irrigated and rainfed wheat plots. Two different information extracted from Sentinel-1 products are used: the backscattering coefficient and the interferometric coherence. A total number of 408 GRD and 419 SLC images were processed for computing the backscattering coefficient and the interferometric coherence, respectively. The analysis of Sentinel-1 time series over the study site show that coherence is sensitive to the development of wheat, while the backscatter coefficient is widely linked to changes in surface soil moisture. Later on, the Water Cloud Model coupled with the Oh et al, 1992 model were used for better understand the backscattering mechanism of wheat canopies. The coupled model is calibrated and validated over the study site and it proved to goodly enough reproduce the Sentinel-1 backscatter with RMSE ranging from 1.5 to 2.52 dB for VV and VH using biomass as a descriptor of wheat. On the other side, the analysis show that coherence is well correlated to biomass. Thus, the calibrated model is used in an inversion algorithm to retrieve SSM using the Sentinel-1 backscatter and coherence as inputs. The results of inversion show that the proposed new approach is able to retrieve the surface soil moisture at 35.2° for VV, with R=0.82, RMSE=0.05m3/m3 and no bias. Using the validation database of Morocco and Tunisia, R is always greater than 0.7 and RMSE and bias are less than 0.008 m3/m3 and 0.03 m3/m3, respectively even that the incidence angle is higher (40°). In order to assess its quality, the approach is compared to four SSM retrieval methods that use radar and optical data in empirical and semi-empirical approaches. Results indicate that the proposed approach shows an improvement of SSM retrieval between 17% and 42% compared to other methods. Finally, the validated new approach is used for SSM mapping, with a spatial resolution of 10*10 m, over irrigated perimeters of wheat in Morocco.

How to cite: Ouaadi, N., Jarlan, L., Ezzahar, J., Khabba, S., Zribi, M., Bouras, E., Bousbih, S., and Frison, P.-L.: Mapping surface soil moisture over wheat crops in southern Mediterranean regions using the backscattering coefficient and the interferometric coherence derived from Sentinel-1, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-7408, https://doi.org/10.5194/egusphere-egu2020-7408, 2020.

EGU2020-6876 | Displays | HS2.1.3

Simple and spatialize approach to optimize irrigation water and wheat yield in the semi-arid areas

Said Khabba, Jihad Toumi, Salah Er-Raki, Jamal Ezzahar, Michel Le Page, Abdelghani Chehbouni, and Lionel Jarlan

In this study, we developed a simple and spatialized wheat yield method based on the Monteith's three efficiency model. The originality of the method consists in: (1) the expression of the conversion coefficient (εconv) by considering an appropriate stress threshold (ksconv) for triggering irrigation, (2) the substitution of the product of the two maximum coefficients of interception (εimax) and conversion (εconv_max) by a single parameter εmax, (3) the modeling of εmax as a function of the Cumulative Growing Degree Days (CGDD) since sowing date, and (4) the dynamic expression of the harvest index HI as a function of the CGDD and the final harvest index HI0 depending of the maximum values of the Normalized Difference Vegetation Index (NDVI).

The calibration and validation of the proposed model were performed by using observed dry matter (DM) and grain yield (GY) on wheat conducted on the irrigated zone R3 of the Haouz plain (center of Morocco), during three agricultural seasons 2002/2003, 2008/2009 and 2012/2013. The model calibration allowed the parameterization of εmax in four periods according to the wheat phenological stages. By contrast, a linear evolution was sufficient to represent the relationship between HI and CGDD. The model validation was performed at the field and regional scales. For the field scale, the obtained results showed a good agreement between the estimated and observed values of DM and GY with Root Mean Square Error (RMSE) of about 1.07 t/ha and 0.57 t/ha for DM and GY, respectively. Likewise, at the regional scale, the proposed approach was tested over the irrigated district (R3) by using Landsat/spot images for mapping GY and DM. The RMSE values were 1.21 t/ha and 0.34 t/ha between measured and simulated DM and GY, respectively.

How to cite: Khabba, S., Toumi, J., Er-Raki, S., Ezzahar, J., Le Page, M., Chehbouni, A., and Jarlan, L.: Simple and spatialize approach to optimize irrigation water and wheat yield in the semi-arid areas, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-6876, https://doi.org/10.5194/egusphere-egu2020-6876, 2020.

EGU2020-2405 | Displays | HS2.1.3

A first look at ERA5 for physically based water balance modelling of the Devoll Catchment, Albania

María Herminia Pesci, Fenja Voges, Nils Rüther, and Kristian Förster

The need for effective water resources management has turned into a major challenge, especially in the face of climate change. Meteorological data is not always readily available and thus the task of predicting the response of hydrological systems becomes complicated. For this reason, climate reanalysis datasets are used as a viable alternative. They combine models with data from satellites and ground sensors and provide consistent long-term meteorological conditions with high temporal resolution. The ERA5 reanalysis dataset was produced and is continuously updated by the European Centre for Medium-Range Weather Forecasts (ECMWF). Within this framework, the ERA5 reanalysis dataset has been applied to predict the hydrological response of the Devoll River catchment in Albania. Due to its location, Albania belongs to the Mediterranean climatic belt, which is characterized by hot dry summers and mild rainy winters. The Devoll River catchment is situated south from the capital city Tirana and covers a surface of around 3140 km2. The flow regime of this catchment consists mainly of snowmelt in the upstream mountainous part, whereas precipitation dominates the lower regions. The simulation of the different flow components was carried out with the latest version of the Water Balance and Simulation Model (WaSiM) on a daily time step. The performance of the simulation was evaluated with the Nash-Sutcliffe (NSE) and the Kling-Gupta (KGE) efficiencies, yielding values of 0.66 and 0.80, respectively. Although the model performance suggests some deficiencies, it is considered satisfactory given that ERA5 is a reanalysis dataset with modelled precipitation fields. From the resulting hydrographs, it is possible to infer that observed and simulated runoff follow the same dynamics and a close correspondence between flow peaks can be achieved. These results finally reinforce the idea of applying ERA5 datasets in cases where meteorological input data availability is low or even absent.

How to cite: Pesci, M. H., Voges, F., Rüther, N., and Förster, K.: A first look at ERA5 for physically based water balance modelling of the Devoll Catchment, Albania, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-2405, https://doi.org/10.5194/egusphere-egu2020-2405, 2020.

EGU2020-10631 | Displays | HS2.1.3 | Highlight

Yearly land cover mapping between 1984 and 2018 in the Haouz plain (Marrakech, Morocco) using robust decision trees approaches.

Vincent Simonneaux, Paul Baby, and Mohamed Hakim Kharrou

Land Cover is a major variable required for agricultural management and biophysical modelling. Remote sensing is the more efficient manner to map this information although robust method are still hardly available especially in semi-arid areas where the development of crops is very heterogeneous, where crops often have low vegetation coverage (e.g. tree plantations) and where several crops are sometimes associated on the same plot (e.g. trees with understory of annuals). Besides, the major problem of classical land cover classification approaches is that they require ground data every year for calibration.

To solve both land cover complexity and ground data availability problems, we propose decision tree approaches based on phenological criteria assumed to remain true for any year. The present work was achieved in the Haouz plain (Marrakech, Morocco) where land cover belongs to six main classes, namely: bare soil, evergreen trees (olive and citrus), deciduous trees (apricot, apple, pomegranate…), winter crops (wheat), summer crops (melon and watermelons), fall crops (peas and broadbean). A decision tree is build based on phonological criteria supposed to be independent of the year, related either to the dynamic of NDVI (min, max and range of NDVI as compared to thresholds) and the period in which the peak or the minimum of NDVI happen (linked respectively to the max of vegetation of annual crops and to the leave fall for trees). This decision tree was applied to map the irrigated areas in the Haouz plain between 1984 and 2018 at yearly time scale using the Landsat archive downloaded from USGS. Only five years with not enough clear images were discarded. The time series obtained are consistent with the known changes that took place in the Haouz plain since 1984, namely a strong development of tree plantations, and of summer crops in some areas. The advantage of processing each year instead of only some key dates (e.g. 3 or 4 images as often encountered in studies when Landsat archive was not so easily available as now) is that it gives a better idea of uncertainties and provides a more robust trend. This work will be continued with estimates of the irrigation water consumption linked with these land cover changes.

How to cite: Simonneaux, V., Baby, P., and Kharrou, M. H.: Yearly land cover mapping between 1984 and 2018 in the Haouz plain (Marrakech, Morocco) using robust decision trees approaches., EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-10631, https://doi.org/10.5194/egusphere-egu2020-10631, 2020.

EGU2020-8635 | Displays | HS2.1.3

Surface Water Management and Modelling in the Sakia El Hamra Hydraulic Basin (Southern Morocco)

Nafia El-alaouy, Aicha Moumni, Badr-eddine Sebbar, Abdeljalil Gouzrou, and Aberrahman Lahrouni

Due to its arid to semi-arid climate, Morocco often faces significant intense rainfall periods that can generate flash floods and raging torrents causing serious damage in a very short period of time. In this context, these recent years, the watershed corresponding to the SAKIA EL HAMRA wadi has known devastating downpours and excessive heavy rains that caused severe floods in Laayoune city and its regions.

The watershed of Sakia El Hamra covers an area of 82000 km2, that drains to Sakia El Hamra wadi, a stream of about 447 km long, crosses the basin in its northern part in the East-to-West direction, to discharge into the Atlantic Ocean at the outlet called Foum El Oued. This zone often experiences dangerous torrents of water and violent flash floods, specifically in the northern part of Laayoune city. For example, a flash flood has occurred at the end of October 2016. The peak flow was far in excess of the average (3000 m3/s against 410m3/s). This river flood, lasted for about 10 h, caused damage to the infrastructure and destruction of agricultural lands near Foum El Oued.

The objective of this study is to investigate, through modelling, the hydrological regime of SAKIA EL HAMRA watershed to prevent the floods in the future and improve warning systems. The hydrological parameters of the watershed were determined by WMS software, namely: zone extent, perimeter, slope, basin’s average elevation, Gravelius compactness index, Horton shape index, average altitude, drainage density and concentration time.

Flood flow return was simulated using the Log-normal distribution, using a long time-series of flow and maximum daily and annual precipitation data, recorded between 1985 and 2016, at the Airport station in Laayoune city. The results showed that during flash floods with known flows, water level can reach up to 13 meters, with high flow velocities flooding hundreds of hectares of surrounding plains at the northern part of the city of Laayoune and agricultural lands near Foum El Oued.

How to cite: El-alaouy, N., Moumni, A., Sebbar, B., Gouzrou, A., and Lahrouni, A.: Surface Water Management and Modelling in the Sakia El Hamra Hydraulic Basin (Southern Morocco), EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-8635, https://doi.org/10.5194/egusphere-egu2020-8635, 2020.

EGU2020-7458 | Displays | HS2.1.3 | Highlight

Agriculture in Southern Mediterranean areas under climate change: Impacts on irrigated wheat grain yield and irrigation requirements

Bouras EL houssaine, Jarlan Lionel, Khabba Said, Er-Raki Salah, Dezetter Alain, Sghir Fathallah, and Yves Tramblay

The southern Mediterranean regions are likely to face drastic climate changes (CC). Agricultural yields, particularly of cereals, could be severely affected, especially if significant changes occur at the key phenological stages. In addition, while agriculture is expected to meet around 83% of North African food demand by 2050, the increase in agricultural water requirements due to the intensification of practices, the extension of arable land and the expected warming could jeopardize the water supply of other key economic sectors. In this context, the present work aims to quantify the impact of CC on the grain yields of irrigated cereals and their water requirements in the Tensift-Haouz region of Morocco. The Med-CORDEX ensemble runs under scenarios RCP4.5 and RCP8.5 are first evaluated and disaggregated using the quantile-quantile approach. The impact of CC on the duration of the main wheat phenological stages based on the degree-day approach is then analysed by considering three typical sowing dates (early, around November 15th; intermediate, around December 15th; and late, around January, 15th). The results show that the rise in air temperature causes a shortening of the development cycle of up to 50 days (around 30%). The impacts of rising temperature, increasing atmospheric CO2 concentration and changes in precipitation on wheat yields are next evaluated, based on the AquaCrop model (previously calibrated on several plots of winter wheat in the region of study), both with and without taking into account the fertilizing effect of CO2. As expected, optimal wheat yields for all climate scenarios and time horizons will decrease on the order of 7 to 30% depending on the sowing date, if CO2 concentration rise is not considered. The results also show that the fertilizing effect of CO2 can counterbalance yield losses, since optimal yields could increase by 7% and 13% respectively at mid-century for the RCP4.5 and RCP8.5 scenarios. Finally, water requirements are expected to decrease by 13 to 42% depending on sowing date, scenario and horizon, mainly in response to the shortening of the cycle. This decrease is associated with a change in temporal patterns, with the requirement peak coming two months earlier than under current conditions. This study provides some quantitative elements for agricultural practices adaptation, in particular concerning the sowing date and also for water management in the south mediterranean region related to the temporal patterns of the crop water needs

How to cite: EL houssaine, B., Lionel, J., Said, K., Salah, E.-R., Alain, D., Fathallah, S., and Tramblay, Y.: Agriculture in Southern Mediterranean areas under climate change: Impacts on irrigated wheat grain yield and irrigation requirements , EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-7458, https://doi.org/10.5194/egusphere-egu2020-7458, 2020.

EGU2020-21910 | Displays | HS2.1.3

Spatialization of meteorological variables over south mediterranean catchments. Case of the Tensift (Morocco).

Ahmed Moucha, Lahoucine Hanich, Simon Gascoin, and Lionel Jarlan

The spatialization of meteorological variables when the ground network is scattered and the relief is disturbed is a major issue for watershed hydrology or for the characterization of agricultural water consumption. The aim of this study is to set up the SAFRAN re-analysis system on the Tensift catchment area in Morocco. To this end, all the meteorological measurements acquired on the site between 2004 and 2014 by several organisations were gathered in a single database and quality control was carried out.  SAFRAN was then assessed according to a leave-one-out approach, which consists of removing a station from the database and comparing the re-analysis with the data from this station. It was also compared to another technic for meteorological variables spatialization named MICROMET (Liston et al., 2006). Particular attention was paid on the mountainous areas. In order to reproduce the high climate variability in this area, SAFRAN is also set up with an irregular grid up to 1 km resolution and compared to the regular version (8 km grid point). The results show that the re-analysis on the irregular grid is much better than on the regular grid, especially in the mountains. For example, the validation at the Aremd mountain station (2058 m) shows that the bias and RMSE on the surface temperature decreased from -4.8°C and 6.2°C for the regular grid to 0.6°C and 3.6°C for the irregular grid. Likewise, for precipitation, the correlation coefficient is improved by more than 23% for the regular grid. Concerning the visible radiation, MICROMET is strongly biased compared to the measurements carried out at the Aremd station (86 W/m²) whereas for SAFRAN, the bias is only 48W/m². Our current work concerns the mapping of vertical soil-vegetation-atmosphere exchanges over the catchment area using SAFRAN forcing on the irregular grid. The challenge is notably to represent irrigation, which strongly modifies the surface water states.

How to cite: Moucha, A., Hanich, L., Gascoin, S., and Jarlan, L.: Spatialization of meteorological variables over south mediterranean catchments. Case of the Tensift (Morocco)., EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-21910, https://doi.org/10.5194/egusphere-egu2020-21910, 2020.

EGU2020-17787 | Displays | HS2.1.3

The influence of large-scale circulation patterns and boundary layer conditions on precipitation formation in Corsica

Isabel Knerr, Katja Trachte, Emilie Garel, Frédéric Huneau, Sébastien Santoni, and Jörg Bendix

The precipitation formation on Corsica in the western Mediterranean is highly affected by the interplay between large-scale weather patterns and the local-scale induced sea-slope breezes. Due to its geographical position the island experiences a strong seasonal cycle in the climatic conditions. From September to May, most of the precipitation is generated by large-scale weather systems, which cause frontal precipitation and in mountainous regions an orographically-induced enhancement. In contrast during the summer month the local combined sea slope breeze systems lead to rather convective precipitation events in the afternoon. The planetary boundary layer (PBL) is the surface affected atmosphere and follows in its structure and height the diurnal cycle. Its height gives information on the strength of turbulent mixing and thus, on the vertical moisture distribution.

In this study we investigate the moisture transport within and above the PBL along a west-east transect on Corsica in the period May 2017 to October 2019. PBL height was derived from wind field measurements with a 3D ultrasound anemometer at the western (Ajaccio) and eastern (Ghisonaccia) coastal sites and from sounding profiles at Ajaccio airport. In addition, the ERA5 reanalysis data along the west-east transect were used to derive the influence of the terrain on the depth of the mixed layer. In order to get further insight into the underlying processes and local mechanisms related to the PBL height development and moisture transport towards the mountains of Corsica the Weather Research and Forecasting (WRF) model is applied. Case studies of summertime convective precipitation formation related to large-scale weather types and local breezes also driven by the sea surface temperatures are presented. Finally, back-trajectory modeling is used to reflect atmospheric pathways and sources of precipitable water.

How to cite: Knerr, I., Trachte, K., Garel, E., Huneau, F., Santoni, S., and Bendix, J.: The influence of large-scale circulation patterns and boundary layer conditions on precipitation formation in Corsica, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-17787, https://doi.org/10.5194/egusphere-egu2020-17787, 2020.

EGU2020-21054 | Displays | HS2.1.3

Streamflow Changes in the Duero River Basin using an Ensemble of Euro-CORDEX Projections

Patricio Yeste, Juan José Rosa-Cánovas, Emilio Romero-Jiménez, Matilde García-Valdecasas-Ojeda, Sonia Raquel Gámiz-Fortis, Yolanda Castro-Díez, and María Jesús Esteban-Parra

Climate change has lead to a generalized decrease of precipitation and an increase of temperature in the Iberian Peninsula during the last decades. These changes will be more intense over the course of the 21th century according to global climate projections. As a consequence, water resources are expected to decrease, particularly in the Duero River Basin.

This study is focused on the hydrological response of the Duero River Basin to the climate change. For this end, firstly, the implementation of the Variable Infiltration Capacity (VIC) model in this Basin has been carried out. The VIC model has been calibrated for the period 2000-2009 with a dataset of daily precipitation, temperature and streamflow. Precipitation and temperature data are extracted from SPREAD/STEAD, a dataset that covers the Peninsular Spain at 0.05º of spatial resolution. Streamflow data are provided by the Spanish Center for Public Work Experimentation and Study (CEDEX, Centro de Estudios y Experimentación de ObrasPúblicas). Subsequently, the VIC model has been validated for the period 2009-2011in order to verify that the model outputs fit well with the observational data.

After the validation of the VIC model for present climate, secondly, the impacts of climate change in the Duero River Basin have been analyzed by developing several future simulations using an ensemble of 18 members from the Euro-CORDEX database and three study periods: 1975-2005 as the historical period; 2020-2050 as the short-term future period, and 2070-2100 as the long-term future period. The Euro-CORDEX simulations for the two future periods are driven under two different Representative Concentration Pathway (RCP) scenarios, RCP 4.5 and RCP 8.5.

The first results of this work show that the VIC model outputs are in good agreement with the observed streamflow, for both the calibration and validation periods. In the context of climate change, a generalized decrease of the streamflow is expected in the Duero River Basin. The results from this study could be of interest for water policy makers and practitioners in the next decades.

Keywords: Duero River Basin, VIC model, climate change, streamflow, projections.

ACKNOWLEDGEMENTS: All the simulations were conducted in the ALHAMBRA cluster (http://alhambra.ugr.es/) of the University of Granada. This work was partially funded by the Spanish Ministry of Economy and Competitiveness projects CGL2013-48539-R and CGL2017-89836-390-R, with additional support from the European Community Funds (FEDER). The first author was supported by the Ministry of Education, Culture and Sport of Spain (FPU grant FPU17/02098).

How to cite: Yeste, P., Rosa-Cánovas, J. J., Romero-Jiménez, E., García-Valdecasas-Ojeda, M., Gámiz-Fortis, S. R., Castro-Díez, Y., and Esteban-Parra, M. J.: Streamflow Changes in the Duero River Basin using an Ensemble of Euro-CORDEX Projections, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-21054, https://doi.org/10.5194/egusphere-egu2020-21054, 2020.

EGU2020-9332 | Displays | HS2.1.3

Evaluation of the potential of Sentinel-1 and Sentinel-1 data for clay content mapping

Safa Bousbih, Mehrez Zribi, Zohra Lili-Chabaane, Nicolas Baghdadi, Azza Gorrab, and Nadhira Ben Aissa

Soil texture is a key parameter in agricultural processes and an important measure for agricultural prediction, water cycle, filtering of pollutants and carbon storage. Besides, its estimation is essential for agronomists, hydrologists, geologists and environmentalists and for modeling in these application areas. Several studies have been based on understanding and modeling the biological, physical and chemical processes in the soil. Regarding the texture of the soil, few researches propose soil texture spatialization, and are generally based on ground measurements. Among other things, field observations or laboratory analyzes are very expensive and are not very representative. Indeed, the soil texture presents a strong heterogeneity even at the scale of a field. It is then necessary to use precise and spatialized information on soils.

These methods are generally based on remote sensing data and particularly optical data to restore soil component. However, these techniques are strongly affected by atmospheric conditions. This constraint is not valid for Radar sensors (Radio Detection And Ranging). Radar data are mainly sensitive to soil moisture and soil roughness, and has also been evaluated for its ability to perform texture measurements.

The aim of this study is evaluate the potential of these techniques based on optical and radar data for soil texture estimation. By its composition, its structure, its texture and its porosity, soil moisture is strongly influenced by the soil nature. With the arrival of Sentinel-1 (S-1) and Sentinel-2 (S-2) ESA spatial missions, data are acquired with high spatial and temporal resolution between July and early December 2017, on a semi-arid area in central Tunisia. This study is therefore conducted using S-2 SWIR (Short-Wave Infrared) bands (B11 and B12, most sensitive to clay) and soil moisture products derived from radar data. And algorithms based on the support vector machine (SVM) and random forest (RF) methods are proposed for the classification and mapping of clay content.

In order to evaluate the approach and determine the adequate data (between optical and radar data) allowing to precisely characterize the clay content, a cross-validation was used. The SWIR bands lead to less satisfactory outcomes compared to soil moisture. With an overall accuracy of approximately 65%, soil moisture achieved the best performance for estimating soil texture. The results also showed that RF and SVM are robust classifiers for texture estimation despite the small number of training data. However, RF displays greater accuracy and speed of simulation compared to SVM.

How to cite: Bousbih, S., Zribi, M., Lili-Chabaane, Z., Baghdadi, N., Gorrab, A., and Ben Aissa, N.: Evaluation of the potential of Sentinel-1 and Sentinel-1 data for clay content mapping, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-9332, https://doi.org/10.5194/egusphere-egu2020-9332, 2020.

EGU2020-9914 | Displays | HS2.1.3

Assessment of hydrological flows in the Po river basin in connection with the underground aquifer

Flavia Fuso, Chiara Righetti, Maurizio Gorla, Oliva Desdemona, and Daniele Bocchiola

We present preliminary results in fulfilment of a Gruppo CAP funded project aiming to evaluate the contribution of the Ticino-Adda TA catchment surface runoff to aquifer recharge of the Lombardia region of Italy. The area of interest is nested within the Po river valley, largely snow/ice fed, and rich in both surface and underground waters, and management of groundwater resources requires thereby assessment of water exchanges between surface and subsurface bodies. Final purpose of this 3-year effort is the production of weather based (IPCC AR5/6) hydrological scenarios in the TA catchment, as boundary conditions for aquifer modeling during 21st century. Here, we report results from Project’s Phase 1, i.e. data based set up of a weather driven, semi distributed hydrological model Poli-Hydro, usable to mimic hydrology of high-altitude catchments watering the Po Valley. The adopted model simulates water budget, including dynamics of glaciers, snow melt, evapotranspiration, and subsequently provides routing time of overland and underground flow at any river section of the river network. In regulated catchments proper operation rules are developed to account for modified flows downstream. We demonstrate model accuracy against historical hydrological information. Modeled daily flows, underground flows, and the contribution of the irrigation systems within the TA can be used as inputs for aquifer dynamics models, to assess control of surface water budget upon aquifer dynamics. Projected hydrological scenarios will be also usable to mimic future hydrogeological dynamics of the area.

How to cite: Fuso, F., Righetti, C., Gorla, M., Desdemona, O., and Bocchiola, D.: Assessment of hydrological flows in the Po river basin in connection with the underground aquifer, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-9914, https://doi.org/10.5194/egusphere-egu2020-9914, 2020.

EGU2020-11333 | Displays | HS2.1.3

Precipitation trends and ruptures effect on catchment hydrology and water resources availability for agricultural lands under climate change

Youness Hrour, Zahra Thomas, Ophélie Fovet, Pauline Rousseau-Gueutin, Pascal Pichelin, and Karima Sebari

Water resources depletion under climate change is a major concern over the world. Mediterranean countries are deeply affected by changes in precipitation intensity, duration and frequency. Such changes lead to decrease in the averaged stream discharge and groundwater recharge consequently decreasing water resources availability. Our research focused on a case study performed in the Loukkos catchment, draining an area of 3730 km², located in the north of Morocco. Trend analysis of 8 to 62 years of precipitations was conducted based on statistical tests at about ten stations over the catchment. 20 to 70 years of temperature and discharge data were also analyzed. The time series were investigated using several non-parametric tests in order to characterize trends, to track down changes and their effect on agricultural land changes at the catchment scale. The present study highlights the impact of climate and catchment hydrology on agricultural practices and water resources used for irrigation. Analysis of precipitation indices showed that the temporal distribution of precipitation in the study area has changed since the 1970s. This change results from a reduction in precipitation, a shift in the hydrological year and a reduction in the number of wet days per year. Severe drought periods appear after the climatic rupture, which occurred around 1971. An increase in the intensity and frequency of droughts, in addition to an increase in the annual and seasonal average temperature (more than 1°C) were observed. Such changes contributed to agricultural practice modifications, with development of irrigated agriculture and later sowing period to adapt to the delay in the onset of the rains. For the future, the use of IPCC/CMIP5 climate projections for the Mediterranean region will help to evaluate how the precipitation indices will evolve. The impact of irrigation on stream discharge and groundwater recharge needs to be considered through agro-hydrological modeling including agricultural trajectory. Such tools will help to strengthen agricultural adaptation strategies and promote resilient farming practices.

Keywords: Precipitation trends, agricultural land use, water use for irrigation, agricultural adaptation strategies.

 

How to cite: Hrour, Y., Thomas, Z., Fovet, O., Rousseau-Gueutin, P., Pichelin, P., and Sebari, K.: Precipitation trends and ruptures effect on catchment hydrology and water resources availability for agricultural lands under climate change, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-11333, https://doi.org/10.5194/egusphere-egu2020-11333, 2020.

EGU2020-11521 | Displays | HS2.1.3

C band radar crops monitoring at high temporal frequency: first results of the MOCTAR campaign

Pierre-Louis Frison, Adnane Chakir, Jamal Ezzahar, Pascal Fanise, Ludovic Villard, Nadia Ouaadi, Khaba Said, Mehrez Zribi, Valerie Le Dantec, Mohamed Kasbani, Salah Erraki, and Lionel Jarlan

This work deals with crops monitoring in a semi-arid environment, the Mediterranean region, where up to 90% of available water is used for irrigation. In addition to help for yield predictions, temporal monitoring at a regular time basis can help for the optimization of water use. We focused on the daily cycle of the backscattering radar coefficient over two different crop Mediterranean types: olive trees and wheat. With a six-day period between two consecutive acquisitions, the Sentinel-1 mission improves significantly the potential of SAR data for seasonal monitoring of earth surfaces. The available temporal frequency allows for the first time the temporal monitoring of natural surfaces in relation with seasonal changes. However, they are still many issues for better understanding Sentinel-1 temporal signatures and the full potential of these data over crop fields. Indeed, crop fields are characterized by contrasted surface states between bare soils and densely vegetated, with sudden changes due to field works (changing dramatically soil roughness or moisture) or harvests.  The MOCTAR experiment consists in the acquisitions of radar fully polarimetric interferometric C-band data acquired continuously at 10 min time step from the top of a tower. The study site is located in the Haouz plain, near the city of Marrakech, in the Chichaoua region, in Morocco. The region is characterized by a semi-arid Mediterranean climate, with an average of 250 mm of yearly precipitation. The region is characterized by two main seasons: wet and dry, extended from October to April and from May to September respectively. Maximum temperatures occur in July-August (average of 27.2 °C) and minimum in January (10.8° C). The study site is composed of two plots of 2.50 ha each, one consisting in olive trees, the other in wheat (Fig. 1). Both are irrigated with drip technique. The study site is documented for more than 10 years, and in situ measurements such as soil moisture, biomass, sapflow sensors (thermal dissipation method) and a micrometric dendrometer are regularly collected.

The radar antennas are fixed on a 20 m height tower, in a similar way than the TropiScat experiment They have been installed in May 2019. Four L-band antennas, two emitting and two receiving, one in H and the other in V polarizations, are visible on the bottom row. Above, six antennas operating at C band are mounted on two rows: four on the bottom one (two emitting and two receiving in H and V pol.) and above two receiving antennas in H and V pol. This configuration allows for interferometric fully polarimetric acquisitions also called PolInSAR. The acquisitions are made continuously with a 10 min time step.

First results show pronounced daily cycles, with amplitude of about 2 dB. These cycles are likely correlated to diurnal variations of tree water content and sap flow, but need to be further investigated sap flows and dielectric constant measurements made on the trunks. These results will be analyzed by comparison with Sentinel-1 temporal profiles.

How to cite: Frison, P.-L., Chakir, A., Ezzahar, J., Fanise, P., Villard, L., Ouaadi, N., Said, K., Zribi, M., Le Dantec, V., Kasbani, M., Erraki, S., and Jarlan, L.: C band radar crops monitoring at high temporal frequency: first results of the MOCTAR campaign, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-11521, https://doi.org/10.5194/egusphere-egu2020-11521, 2020.

EGU2020-14106 | Displays | HS2.1.3

On the use of different approaches based on photochemical reflectance index and surface temperature to monitor the water status of winter wheat in semi-arid regions

Zoubair Rafi, Valérie Le Dantec, Olivier Merlin, Said Khabba, Patrick Mordelet, and Salah Er Raki

Agriculture is considered to be the human activity that consumes the most mobilized water on a global scale. However, crops planted in semi-arid areas regularly face periods of moderate to extreme water stress. Such water stress periods have a considerable impact on the seasonal yield of these crops. In order to participate in a more rational irrigation water management, monitoring of the rapid changes in plant water status is necessary. For this purpose, the combination of two different wavelength ranges will be explored : an index based on Xanthophyll cycle (Photochemical Reflectance Index, PRI) and a commonly-used index from thermal infrared spectral range (LST). An experiment on winter wheat was carried out over two agricultural campaigns (2016 to 2018) in the Haouz basin, which is located in the Marrakech region, to better assimilate the temporal dynamics of PRI and surface temperature. In this study, four different approaches are proposed to study the functioning of wheat : 1- an approach based on solar angle to remove the structure effect (PRI0) from the PRI signal and to derive a water stress index PRIj, 2- an approach based on global radiation (Rg) to extrapolate a theoretical PRI (PRIth) for Rg equal to zero and to calculate a water stress index PRIlin, 3- an approach that determines an optimal PRI (PRIpot) on the basis of the available water content (AWC) criterion in order to derive a stress index I-PRI and 4- an energy balance approach to extract dry and wet surface temperatures in order to establish a normalized surface temperature index (Tnorm). The results of this work show a strong correlation between the PRI0 and the Leaf Area Index with a coefficient of determination equal to 0.92, indicating that it is possible to isolate the structural effects of wheat on the PRI signal. In addition, over the range of variation in AWC, a significant correlation with PRIj, PRIjlin and I-PRI was observed with coefficients of determination of 0.71, 0.42 and 0.24, respectively. In contrast to the Tnorm, which varies only for values of AWC below 30%, a coefficient of determination of 0.22 is obtained. Finally, the PRI allows us to acquire early and complete information on the response of wheat to change in AWC as opposed to the surface temperature index, revealing the potential of the PRI to monitor the water status of plants and their responses to changing environmental conditions.

How to cite: Rafi, Z., Le Dantec, V., Merlin, O., Khabba, S., Mordelet, P., and Er Raki, S.: On the use of different approaches based on photochemical reflectance index and surface temperature to monitor the water status of winter wheat in semi-arid regions, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-14106, https://doi.org/10.5194/egusphere-egu2020-14106, 2020.

EGU2020-8588 | Displays | HS2.1.3

Detection of irrigation events on maize plots using sentinel-1 soil moisture products

Michel Le Page, Lionel Jarlan, Aaron Boone, Mohammad El Hajj, Nicolas Baghdadi, and Mehrez Zribi

An accurate knowledge of irrigation timing and rate is essential to compute the water balance of irrigated plots. However, at the plot scale irrigation is a data essentially known by the irrigator. These data do not go up to higher management scales, thus limiting both the management of water resources on a regional scale and the development of irrigation decision support tools at the farm scale. The study focuses on 6 experimental plots in the south-west of France. The new method consists in assessing surface soil moisture (SSM) change between observations and a water balance model. The approach was tested using both in situ measurements and surface soil moisture (SSM) maps derived from Sentinel-1 radar data. The score is obtained by assessing if the irrigation event is detected within +/- three days. The use of in situ SSM showed that: (1) the best revisit time between two SSM observations is 3 days; short gaps is subject to uncertainties while longer gap miss possible SSM variations; (2) in general, higher rates (>20mm) of irrigation are well identified while it is very difficult to identify irrigation event when it is raining or when irrigation rates are small (<10mm). When using the SSM microwave product, the performances are degraded but are still acceptable given the discontinuity of irrigation events: 34% of absolute error and a bias of 5% for the whole season. Although high vegetation cover degrades the SSM absolute estimates, the dynamic appeared to be in accordance with in-situ measurements.

How to cite: Le Page, M., Jarlan, L., Boone, A., El Hajj, M., Baghdadi, N., and Zribi, M.: Detection of irrigation events on maize plots using sentinel-1 soil moisture products, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-8588, https://doi.org/10.5194/egusphere-egu2020-8588, 2020.

EGU2020-8614 | Displays | HS2.1.3

Modified Shuttleworth-Wallace model for monitoring evapotranspiration over complex surface: Relationship between the surface resistances and remotely sensed stress indexes

Jamal Elfarkh, Salah Er-Raki, Jamal Ezzahar, Abdelghani Chehbouni, Bouchra Aithssaine, Abdelhakim Amazirh, Said Khabba, and Lionel Jarlan

The main goal of this work was to evaluate the potential of the Shuttleworth-Wallace (SW) model for mapping actual crop evapotranspiration (ET) over complex terrain located within the foothill of the Atlas Mountain (Morocco). This model needs many input variables to compute soil (rss) and vegetation (rsv) resistances, which are often difficult to estimate at large scale particularly soil moisture. In this study, a new approach to spatialize rss and rsv based on two thermal-based proxy variables is proposed. Land Surface Temperature (LST) and Normalized Difference Vegetation Index (NDVI) derived from LANDSAT data were combined with the endmember temperatures  for soil (Tsmin and Tsmax) and vegetation (Tvmin and Tvmax), which are simulated by a surface energy balance model, to compute the temperature of the two components, namely the soil (Ts) and the vegetation (Tv). Based on these temperatures, two thermal proxies (SIss for soil and SIsv for vegetation) were calculated and related to rss and rsv, with an empirical exponential relationship (with a correlation coefficient (R) of about 0,6 and 0,5 for soil and vegetation, respectively). The proposed approach was firstly evaluated at a local scale, by comparing the results to observations by an eddy covariance system installed over an area planted with olive trees intercropped with wheat. In a second step, the new approach was applied over a large area which contains a mixed vegetation (tall and short vegetation) crossed by a river to derive rss and rsv, and thereafter to estimate ET. A Large aperture scintillometer (LAS) installed over a transect of 1.4 km and spanning the total area is used to validate the obtained ET. The comparison confirms the ability of the proposed approach to provide satisfactory ET maps with an RMSE and R2 equal to 52.51 W/m2 and 0.80, respectively.

How to cite: Elfarkh, J., Er-Raki, S., Ezzahar, J., Chehbouni, A., Aithssaine, B., Amazirh, A., Khabba, S., and Jarlan, L.: Modified Shuttleworth-Wallace model for monitoring evapotranspiration over complex surface: Relationship between the surface resistances and remotely sensed stress indexes, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-8614, https://doi.org/10.5194/egusphere-egu2020-8614, 2020.

EGU2020-15757 | Displays | HS2.1.3

Gradual transition from temperature to precipitation controlled regime in Rhone River discharges

Carla Taricco, Sara Rubinetti, Enrico Arnone, Davide Zanchettin, Angelo Rubino, and Ilaria Bizzarri

River discharge series provide large-scale hydrological information over a broad range of timescales. Despite discharge records consist of punctual measurements, they integrate variations in snowmelting, precipitation and runoff processes over the catchment till the discharge measurement site.

Discharges of the Rhone River, one of the largest rivers in Europe, have been monitored accurately during the last century at different sites. Long discharge records from seven stations along the course reveal the spatial and temporal behaviour of discharges from the source of the river to its mouth.  An accurate spectral analysis of the records, performed using advanced spectral analysis methods, allow us to extract significant periodic variations in the records at different temporal scales. Then, we analyse the sensitivity of such periodic variations to evolving hydroclimate conditions, in particular focusing on the relationship between discharge and temperature and precipitation.

The strong annual oscillation recorded at stations close to the source is almost entirely due to snow melting on alpine glaciers, closely resembling the temperature annual cycle. This remarkable agreement allows to consider the upstream discharges as a thermometer on the glacier region during the melting season. On the contrary, the decrease of the annual cycle going towards the mouth of the river and the contemporary growth of interannual components demonstrates the transition from a temperature to a precipitation controlled discharge regime.

We will finally discuss the impact of large-scale variability patterns on the detected discharge variations and associated implications for their near-term predictability.

How to cite: Taricco, C., Rubinetti, S., Arnone, E., Zanchettin, D., Rubino, A., and Bizzarri, I.: Gradual transition from temperature to precipitation controlled regime in Rhone River discharges, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-15757, https://doi.org/10.5194/egusphere-egu2020-15757, 2020.

EGU2020-1108 | Displays | HS2.1.3

Changes of hydrological regime in the mountain catchments of the Crimean Peninsula

Anastasiia Zemlianskova, Olga Makarieva, Nataliia Nesterova, and Danil Arkhipov

Crimean water resources are unevenly distributed and mainly generated at the slopes of the Crimean Mountains affecting water supply of population and industry of the peninsula. The study of water resources has been limited for the last 30 years due to political situation and little quantitative information is available about climate change impact on hydrological regime of Crimean rivers. The aim of the study was the assessment of current flow characteristics for three rivers originating from the Crimean Mountains (the Derekoyka River at Yalta; 49.7 km2, the Demerdjy River at Alyshta, 53 km2; the Kokkozka River at Golybinka, 83.6 km2) and their comparison to the historical period (1960-1990) data. The study area is characterized by a Mediterranean climate and has a pronounced high-altitude zoning. Main vegetation type is the oak forests and shrubs. The highest elevation of the slopes reaches 1500 m.

Due to the lack of hydrological data for the last 30 years, the assessment of current flow characteristics was conducted based on hydrological modelling and observed meteorological data. The hydrological model Hydrograph was used in the study. The model was successfully used for the simulations of streamflow in similar climate for the basins of the Black Sea coast of Russia (Makarieva et al., 2018; 2019). The model was parametrized based on the data on typical landscapes of the studied area. The verification of streamflow and water balance simulation results was conducted for the historical period (1960-1990). The model was used to produce streamflow hydrographs for the period of 1991-2018 based on meteorological data. The changes of hydrological regime of Crimean rivers was assessed in comparison with historical period. The results of the study will be presented.

How to cite: Zemlianskova, A., Makarieva, O., Nesterova, N., and Arkhipov, D.: Changes of hydrological regime in the mountain catchments of the Crimean Peninsula, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-1108, https://doi.org/10.5194/egusphere-egu2020-1108, 2020.

EGU2020-3127 | Displays | HS2.1.3

Driving factors of non-linearity rainfall-runoff relationships at different time scales in small Mediterranean-climate catchments

Josep Fortesa, Jérôme Latron, Julián García-Comendador, Miquel Tomàs-Burguera, Jaume Company, Aleix Calsamiglia, and Joan Estrany

The complexity of Mediterranean fluvial systems is caused by the multiple temporal and spatial heterogeneity in the relationships between the natural and human-induced abiotic and biotic variables. Accordingly, Mediterranean rivers are characterized by a large heterogeneity in hydrological regimes promoting significant temporal and spatial differences in the hydrological response.

This research investigates the non-linearity in the rainfall-runoff relationship at multiple temporal scales to achieve a better understanding of the hydrological response in representative small Mediterranean-climate catchments (i.e., < 10 km2). Rainfall-runoff was evaluated at annual and event scales. At annual scale, data from 43 catchments were collected to assess the influence of lithology on runoff response. At event scale, 203 events from 12 catchments were classified according to (a) seasonal occurrence (autumn, winter, spring or summer), (b) pervious or impervious lithology and (c) main land use (agricultural, agroforestry, forest or shrub). Besides, the inter- and intra-annual variability of the rainfall-runoff and the temporal downscaling (i.e., annual to event scale) was studied in Es Fangar Creek catchment (3.35 km2; Mallorca, Spain) during five hydrological years (2012-2017).

The assessment of rainfall-runoff relationships at annual scale in small Mediterranean-climate catchments showed a strong linearity in the hydrological response due to the importance of the annual rainfall amount. However, lithology effects on runoff generation explained an increase of the scattering in these relationships because pervious and impervious materials triggered larger and lower runoff contribution respectively. Although the significant correlation between rainfall and runoff, Es Fangar Creek dataset illustrated a huge intra-annual variability of the rainfall-runoff relationship as seasonal rainfall and evapotranspiration dynamics controlled the runoff response. These dynamics were observed in the average seasonal runoff coefficients, decreasing from winter to summer. These differences should be considered as a starting point of the non-linearity generation in the rainfall-runoff relationships at event scale.

At event scale, lineal and non-lineal performances were observed in the rainfall-runoff relationships in small Mediterranean-climate catchments suggesting that different factors conditioned the runoff response. Total rainfall was the most significant driver factor although the interaction between seasonality and the spatial diversity of lithology and land uses at catchment scale also played an important role on runoff generation. Thus, the highest correlations at seasonal scale were observed in those events occurred in winter and spring when the highest water reserves favoured the runoff response. Lithology caused higher dispersion in rainfall-runoff relationships at event scale in the set of small Mediterranean-climate catchments because pervious materials required higher antecedent wetness conditions. Agricultural land uses promoted the highest runoff generation. 

These findings will improve the comprehension of hydrological processes as the temporal downscaling of rainfall-runoff linked to the driven factors with the linearity and non-linearity knowledge is needed for accuracy and precision into hydrological modelling at event scale.

This work was supported by the research project CGL2017-88200-R “Functional hydrological and sediment connectivity at Mediterranean catchments: global change scenarios –MEDhyCON2” funded by the Spanish Ministry of Science, Innovation and Universities, the Spanish Agency of Research (AEI) and the European Regional Development Funds (ERDF). 

How to cite: Fortesa, J., Latron, J., García-Comendador, J., Tomàs-Burguera, M., Company, J., Calsamiglia, A., and Estrany, J.: Driving factors of non-linearity rainfall-runoff relationships at different time scales in small Mediterranean-climate catchments, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-3127, https://doi.org/10.5194/egusphere-egu2020-3127, 2020.

EGU2020-14815 | Displays | HS2.1.3

Linking hydrological response to forest dynamics in Mediterranean areas: a new experimental catchment in the Apennine Mountains, Tuscany, Italy

Daniele Penna, Marco Borga, Elena Bresci, Giulio Castelli, Pietro Castellucci, Claudia Cocozza, Alessandro Errico, Ginevra Fabiani, Laurent Gourdol, Julian Klaus, Francesca Sofia Manca di Villahermosa, Laurent Pfister, Federico Preti, Cyrille Tailliez, Paolo Trucchi, Matteo Verdone, and Giulia Zuecco

The bi-directional ecohydrological interactions between forest dynamics and catchment hydrological response in Mediterranean forest ecosystems remain poorly conceptualized. Understanding the effect of tree water uptake and transpiration patterns on how catchments store and release water and, vice versa, on how catchment water availability affects tree physiological response is of paramount importance for forest and water resource management. This is crucial in the light of the predicted prolonged drought periods that will exacerbate the dry summer spells that characterize Mediterranean areas. In order to address these pressing issues, a new experimental mountain forested catchment for interdisciplinary ecohydrological research has been recently implemented in the Tuscan Apennines (Italy).

 

The catchment size is 2 km2 and elevation ranges from 650 to 1280 m a.s.l.. Forest covers more than 95% of the area, and the main tree species are beech and oak trees, with a much smaller proportion of conifers. Mean annual precipitation is around 1180 mm. Instrument installation is currently in progress and supported by two research projects (run in parallel in Italy and Luxembourg). By spring 2020, the catchment is expected to host the following equipment: one weather station plus one additional rain gauge, including a rainfall collector for isotope analysis; four stream gauges at different spatial scales (from a 2-ha headwater subcatchment to the catchment outlet) including continuous electrical conductivity measurements; three groundwater wells (ranging from 2 to 5 m depth) equipped with water level and electrical conductivity loggers; a network of soil moisture sensors at different depths; stemflow collectors; rain totalizers for manual throughfall measurements; a network of innovative multi-parametric sensors mounted on individual beech trees for continuous measurement (logging to cloud) of physiological and micro-meteorological parameters (sap flow, stem radial growth, canopy light transmission, stem wood temperature and humidity, 3D position over time, and air temperature and relative humidity).

 

Preliminary data collected in 2019 show a marked seasonality of stream runoff, with low runoff coefficients in summer (<0.1), consistent with the high drainage of forested soils and large evapotranspiration fluxes. Stream electrical conductivity values increase from upstream to downstream sections, showing a consistent spatial variability among seasons and suggesting an increasingly relevance of subsurface flow for sustaining baseflow. Marked diel fluctuations in stream water levels during sunny summer days suggest a dominant control of tree transpiration on streamflow. Near-surface soil moisture spatial patterns at the hillslope scale show strong temporal stability. Future experimental activities will assess water pools used by beech trees along a hillslope. Planned tools and research include water stable isotopes, seasonal variations in canopy interception, stemflow, and throughfall as well as the spatio-temporal variability of soil moisture patterns at the plot, hillslope, and catchment scale.

How to cite: Penna, D., Borga, M., Bresci, E., Castelli, G., Castellucci, P., Cocozza, C., Errico, A., Fabiani, G., Gourdol, L., Klaus, J., Manca di Villahermosa, F. S., Pfister, L., Preti, F., Tailliez, C., Trucchi, P., Verdone, M., and Zuecco, G.: Linking hydrological response to forest dynamics in Mediterranean areas: a new experimental catchment in the Apennine Mountains, Tuscany, Italy, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-14815, https://doi.org/10.5194/egusphere-egu2020-14815, 2020.

EGU2020-10212 | Displays | HS2.1.3

Impact of climate change in Mediterranean river basins: relation between droughts, vegetation and reduction of waterdischarge

Camille Labrousse, Wolfgang Ludwig, Guillaume Lacquement, and Mahrez Sadaoui

Abstract:

The Languedoc-Roussillon region is a Mediterranean area located Southern France and composed of 6 main coastal river catchments about 1000 to 4800 km2 each and discharging to the Gulf of Lion. A first study investigating evidences of climatic changes in the river basins showed a significant reduction of the waterdischarge of 20 % in average in the whole area during the period 1965-2004 (40 years).By including the most recent years (up to 2018), the time series demonstrate that the decline in water discharge still continues and could consequently have been reduced by more than 40% since the years 1960. Thus, understanding the relation and effect of climatic changes on hydrology is essential for the development of water resource strategies.

In this study, we examine and analyse the long-term dynamics of the drought indices as climatic parameters and the impact of their changes on the 6 coastal river waterdischarge at the annual and seasonal scales. ­­­We investigate the meteorological, and agricultural droughts as well as the vegetation density’s evolution through time and compute statistical analysis to understand the linkage with the reduction of waterdischarge. First results show a trend toward dryer years as well as a strong correlation between mean annual hydrological variations and drought indices.

How to cite: Labrousse, C., Ludwig, W., Lacquement, G., and Sadaoui, M.: Impact of climate change in Mediterranean river basins: relation between droughts, vegetation and reduction of waterdischarge, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-10212, https://doi.org/10.5194/egusphere-egu2020-10212, 2020.

EGU2020-21993 | Displays | HS2.1.3 | Highlight

Building quantitative scenarios of irrigation under climatic and anthropogenic changes in the mediterranean area: application to Morocco

Fakir Younes, Le Page Michel, Jarlan Lionel, Boone Aaron, Berjamy Brahim, and Molle François

In a context of major changes (climate, demography, economy, etc.), the Southern Mediterranean area faces serious challenges with intrinsically low, irregular and continuously decreasing water resources. A method for translating a narrative scenario of irrigation water requirements into a quantitative scenario is presented. At first, we propose to describe the Irrigation Water Requirements (IWR) of any area by a single equation. IWR depends on climate (ET0, Rainfall), crop development estimated from remote sensing time series (crop coefficient/NDVI relationships), and four efficiencies parameters. In a second part, a reference model of the crop coefficient monthly cycle ( ) is proposed by empirically relating to rainfall and NDVI. Three variations of the model are compared in order to make a projection until 2050 based on downscaled climate change scenarios. The reliability of the model depends on the representativeness of the calibration period: It is considered to be high at the beginning of the simulation (RMSE below 0.1), but it deteriorates as the calibrating period gets shorter compared to the objective period: r2= 0.5, RMSE = [0.1-0.14], stderr = [0.02-0.03] by 2050. An alternative scenario is built upon the reference by interpreting the narrative as bending points. Finally, the examination of irrigation water demand until 2050 suggests that the difference between the two climate scenarios is very small (<2%), while the two proposed agricultural scenarios are strongly contrasted both spatially and in their impact on water resources.

How to cite: Younes, F., Michel, L. P., Lionel, J., Aaron, B., Brahim, B., and François, M.: Building quantitative scenarios of irrigation under climatic and anthropogenic changes in the mediterranean area: application to Morocco, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-21993, https://doi.org/10.5194/egusphere-egu2020-21993, 2020.

EGU2020-8751 | Displays | HS2.1.3

Assessing soil moisture constraint on soil evaporation and plant transpiration fractioning

Bouchra Ait Hssaine, Olivier Merlin, Jamal Ezzahar, Salah Er-raki, Saïd Khabba, and Abdelghani Chehbouni

Over semi-arid agricultural regions, detecting the crop water need at the onset of water stress is of paramount importance for optimizing the use of irrigation water. Evapotranspiration (ET) is a crucial component of the water cycle, it strongly impacts the water resource management, drought monitoring, and climate. Remote sensing observations provide very relevant information to feed ET models. In particular, the microwave-derived surface (0-5 cm) soil moisture (SM), which is the main controlling factor of soil evaporation, the visible/near-infratred-derived vegetation cover fraction (fc), which provides an essential structural constraint on the fractioning between vegetation transpiration and soil evaporation, and - thermal-derived land surface temperature (LST), which is a signature of both available energy and evapotranspiration (ET) rate. The aim of this work is to integrate those independent and complementary information on total ET within an energy balance model. As a state-of-the-art and commonly used model, we chose the TSEB modelling as a basis for developments. An innovative calibration procedure is proposed to retrieve the main parameters of soil evaporation (soil resistance, rss) and plant transpiration (Priestly Taylor coefficient, αPT) based on a threshold on fc. The procedure is applied over an irrigated wheat field in the Tensift basin, central Morocco. Overall, the coupling of the soil resistance formulation with the TSEB formalism improves the estimation of soil evaporation, and consequently, improves the partitioning of ET. Analysis of the retrieved time series indicates that the daily αPT mainly follows the phenology of winter wheat crop with a maximum value coincident with the full development of green biomass and a minimum value reached at harvest. The temporal variations of αPT before senescence are attributed to the dynamics of both the root zone soil moisture and the amount of green biomass.

How to cite: Ait Hssaine, B., Merlin, O., Ezzahar, J., Er-raki, S., Khabba, S., and Chehbouni, A.: Assessing soil moisture constraint on soil evaporation and plant transpiration fractioning, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-8751, https://doi.org/10.5194/egusphere-egu2020-8751, 2020.

HS2.1.5 – Advances in African Hydrology and Climate: Modelling, Water Management, Environmental and Food Security

EGU2020-11529 | Displays | HS2.1.5

Climate Observations in 22 African Countries at 550 locations: the TAHMO network

John Selker, Nick van de Giesen, and Frank Annor

The Trans-African Hydro-Meteorological Observatory (TAHMO) was officially founded as a not-for-profit foundation in 2014. TAHMO has become the largest provider of scientific weather and climate data for sub-Sahara Africa, with over 500 stations in 22 countries, and a goal of 20,000.  The projection for 2020 is to have 800 stations running and reporting.  TAHMO has successfully shown that it is possible to run a high-quality cost-effective observation network in Africa through investing in relationships, strategic innovation in technology, management, and on-the-ground operations.

 

Technology -TAHMO partnered with METER Group in the co-design of the weather station. Originally, the thought was to develop a very cheap ($200) station, but robustness and accuracy were the driving goals, leading to a station with costs closer to $2000.  Many ideas have been bounced between the two teams and tested in the field in Africa, with no fewer than three generations of technology having been tested.

 

Operation - Over 90% of TAHMO stations are placed at (secondary) schools. This provides physical and, moreover, social protection. Educational material is provided to engage teachers and students and to encourage them to help out with simple maintenance, such as cleaning.

 

Financial sustainability - Stations have been funded through projects funded largely by donors and agencies. A large investment by IBM / Weather Underground formed the basis for a rapid expansion of 333 stations. To ensure long-term financial sustainability, TAHMO provides data services to commercial users, wherein the value chain run from raw data to actionable information. For this reason, TAHMO has become part of a network of entities that bridge the gap between weather station and information market. TAHMO provides data to the research enterprise and host governments at no cost.

 

How to cite: Selker, J., van de Giesen, N., and Annor, F.: Climate Observations in 22 African Countries at 550 locations: the TAHMO network, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-11529, https://doi.org/10.5194/egusphere-egu2020-11529, 2020.

EGU2020-14125 | Displays | HS2.1.5

Climate change impacts on crop water productivity in Africa using a multi-model inter-comparison

Imeshi Weerasinghe, Celray James Chawanda, and Ann van Griensven

Evapotranspiration (ET) or the water vapour flux is an important component in the water cycle and is widely studied due to its implications in disciplines ranging from hydrology to agricultural and climate sciences. In the recent past, growing attention has been given to estimating ET fluxes at regional and global scales. However, estimation of ET at large scales has been a difficult task due to direct measurement of ET being possible only at point locations, for example using flux towers. For the African continent, only a limited number of flux tower data are openly available for use, which makes verification of regional and global ET products very difficult. Recent advances in satellite based products provide promising data to fill these observational gaps.

In this study we propose to investigate the Climate Change (CC) impact on crop water productivity across Africa using ET and crop yield predictions of different crop models for future climate scenarios. Different model outputs are evaluated including models from both the ISI-MIP 2a and 2b protocols. Considering the problem of direct observations of ET being difficult to obtain, especially over Africa, we use ET estimates from several remotely sensed derived products as a references to evaluate the crop models (maize) in terms of magnitude, spatial patterns and variations between models. The crop model results for crop yield are compared to FAO reported crop yields at country scale. The results show a very strong disagreement between the different crop models of the baseline scenario and when compared with ET and crop yield data.  Also, a very large uncertainty is obtained for the climate change predictions. It is hence recommended to improve the crop models for application in Africa.

How to cite: Weerasinghe, I., Chawanda, C. J., and van Griensven, A.: Climate change impacts on crop water productivity in Africa using a multi-model inter-comparison, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-14125, https://doi.org/10.5194/egusphere-egu2020-14125, 2020.

EGU2020-10106 | Displays | HS2.1.5

Investigating the role of the Cuvette Centrale wetlands in the hydrology, sediment and carbon fluxes of the Congo River basin

Pankyes Datok, Clément Fabre, Sabine Sauvage, Guy Moukandi, Adrien Paris, Vanessa Dos Santos, Alain Laraque, and José Sànchez-Pérez

Keywords: Cuvette Centrale, Hydrology, Sediments, Carbon,

The Congo River basin is among the largest Rivers in the world in terms of discharge and drainage area. At the heart of the basin lies the Cuvette Centrale-one of the most extensive wetlands in the world. The increasing pressure on wetland resources continues to threaten the role wetlands play in maintaining water resources and ecological service functions. Therefore, in order to understand the role of the Cuvette Centrale in water resources and ecological service functions linked to the quality of water and life in the basin, we first need to quantify its role in the hydrological, sediment and carbon dynamics. To achieve this aim, we use the Soil and Water Assessment Tool model (SWAT) – modified for tropical environments, in order to analyze the hydrology, sediment and organic carbon fluxes flowing in and flowing out of the Cuvette Centrale of the Congo River basin (CRB). The model was calibrated and validated for the 2000-2006 and 2007-2012 periods respectively by comparing the discharge and sediment output with different data sources (gauging stations and altimetry) at a daily and monthly time step. Then by adapting equations of dissolved organic carbon (DOC) and particulate organic carbon (POC) from literature, we are able to quantify the role of the Cuvette Centrale in the CRB carbon dynamics.The results reveal that the models for hydrology, sediments and carbon can represent both temporally and spatially the exports in a watershed and sheds more light on the important regulatory function of the Cuvette and the need for sustainable land use practices as well as protection of ground water resources  in order to maintain wetland water quantities and quality.

How to cite: Datok, P., Fabre, C., Sauvage, S., Moukandi, G., Paris, A., Dos Santos, V., Laraque, A., and Sànchez-Pérez, J.: Investigating the role of the Cuvette Centrale wetlands in the hydrology, sediment and carbon fluxes of the Congo River basin, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-10106, https://doi.org/10.5194/egusphere-egu2020-10106, 2020.

EGU2020-642 | Displays | HS2.1.5

Understanding factors influencing the wetland parameters of a monthly rainfall-runoff model in the Upper Congo River basin

Pierre Kabuya, Denis Hughes, Raphael Tshimanga, and Mark Trigg

Wetland processes considerably influence the flow regime of the downstream river channel, and are important to consider for a better representation of runoff generation within a basin scale hydrological model. The need to understand these processes lead to the development of a wetland sub-model for the monthly time step Pitman hydrological model. However, previous studies highlighted the need to provide guidance to explicitly estimate the wetland parameters rather than using a trial and error calibration approach. In this study, a 2D hydrodynamic river-wetland model (LISFLOOD-FP) is used to explicitly represent the inundation process exchanges between river channels and wetland systems and thereby inform the choice of Pitman wetland model parameters. The hysteretic patterns of these river-wetland processes are quantified through the use of hysteresis indices. Additionally, the hysteretic patterns are connected with the spill and return flow parameters of the wetland sub-model and eventually with the wetland morphometric characteristics. The results show that there is a consistent connection between the degree of hysteresis found in the channel-wetland exchange processes and the Pitman wetland parameters which are also explicitly linked to the wetland morphometric characteristics. The channel capacity to spill (Qcap) is consistently correlated with the hysteresis found between the channel inflow and the wetland storage volume. This anti-clockwise hysteresis represents the time delay between the inundation and drainage processes. The channel spill factor (QSF), in addition to the inundation processes, is also connected with the drainage processes represented by the wetland storage volume and channel outflow anti-clockwise hysteresis. On the other hand, the parameters of the return flow equation have shown a strong consistent relationship with the channel inflow-wetland storage hysteresis. It has also been observed that the wetland average surface slope and the proportion of the wetland storage below the channel banks are the morphometric characteristics that influence the spill and the return flow parameters of the Pitman wetland sub-model. This understanding has a practical advantage for the estimation of the Pitman wetland parameters in the many areas where it is not possible to run complex hydrodynamic models.

How to cite: Kabuya, P., Hughes, D., Tshimanga, R., and Trigg, M.: Understanding factors influencing the wetland parameters of a monthly rainfall-runoff model in the Upper Congo River basin, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-642, https://doi.org/10.5194/egusphere-egu2020-642, 2020.

EGU2020-1154 | Displays | HS2.1.5

Socio-economic determinants of land use/cover change in wetlands in East Africa: a case study analysis of the Anyiko wetland, Kenya

Risper Ajwang, Francesco Vuolo, Julius Kipkemboi, Nzula Kitaka, Erwin Lautsch, Thomas Hein, and Erwin Schmid

In East Africa, wetlands are steadily converted to agriculture for food security reasons. This study analyzed high spatial resolution panchromatic and color photographs in the Anyiko wetland in Kenya to reveal wetland conversions between 1966 and 2018. Socio-economic determinants of land use/cover change are also assessed in the Anyiko wetland. Socio-economic data was collected through a questionnaire survey of 226 households. A CHi- squared Automatic Interaction Detector (CHAID) decision tree approach is utilized to assess determinants of wetlands conversion. The results showed that between 1966 and 2018, the wetland area reduced by 55%, mostly attributed to agricultural development. Households were more likely to cultivate the wetland if they did not harvest papyrus for artisanal products, were male-headed and lacked alternative sources of income. The perceptions that wetland is “wasteland” and conversion to agriculture provides higher net monetary benefit did not influence wetland cultivation. Hence, the conversion of the wetland was determined by the socio-economic status of the households rather than perceptions on its value.

How to cite: Ajwang, R., Vuolo, F., Kipkemboi, J., Kitaka, N., Lautsch, E., Hein, T., and Schmid, E.: Socio-economic determinants of land use/cover change in wetlands in East Africa: a case study analysis of the Anyiko wetland, Kenya, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-1154, https://doi.org/10.5194/egusphere-egu2020-1154, 2020.

EGU2020-16534 | Displays | HS2.1.5

Seasonal Hydrometeorological Forecasts for Water Managment in West- and Northeast Africa: Development, Operationalisation and Performance of a Regional Prediction System

Harald Kunstmann, Christof Lorenz, Tanja Portele, Patrick Laux, Jan Bliefernicht, Seyni Salack, Ammar Gaber, and Yasir Mohammed

It is the knowledge of the coming months that can be crucial for the management and control of water reservoirs for hydropower generation or for irrigation. This is particularly important in semi-arid regions of Africa that are characterized by distinctive dry seasons, i.e. where rainfall is limited to few months only. In addition, observation data in Africa are usually extremely sparse and computational power for forecasting systems is difficult to access. We present the spatial disaggregation and bias-correction of the globally available ECMWF’s newest seasonal forecast system SEAS5 and its tailored operational processing to support local water resources management and decision-makers. The forecast horizon is up to 7 month lead time, and our final forecasts have 0.1° spatial resolution. For the retrospective years 1981 till 2016 our ensemble consists of 25 members, while for the ongoing forecasts since 2017 there are 51 members available, allowing probabililistic predictions The performance of the regional prediction system is presented for 1) the Tekeze-Atbara and Blue Nile basins in Eithiopia/Sudan, and 2) the Volta and Niger basins in West Africa. The evaluation against the reference ERA5 data shows significant reduction in biases from the monthly averages as well as consistent and lead-independent forecasts characteristics like wet/dry frequencies. The performance metrices considered comprise accuracy (mean absolute error skill score), overall performance (continuous ranked probability skill score), sharpness (interquantile range skill score) and reliability. The operationalized system provides seasonal predictions each month to support water management on regional and local levels.

How to cite: Kunstmann, H., Lorenz, C., Portele, T., Laux, P., Bliefernicht, J., Salack, S., Gaber, A., and Mohammed, Y.: Seasonal Hydrometeorological Forecasts for Water Managment in West- and Northeast Africa: Development, Operationalisation and Performance of a Regional Prediction System, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-16534, https://doi.org/10.5194/egusphere-egu2020-16534, 2020.

EGU2020-1274 | Displays | HS2.1.5

Assessment of the potential for irrigation development in Albert Nile basin: A case study of Nebbi district

Nicholas Kiggundu, Charles Bwire, and Joshua Wanyama

There has been limited research conducted on irrigation potential in Uganda. The existing studies provide a wide number of estimates of irrigation potential for Uganda and thus constrain reliable medium term planning and investment in the subsector. This research was aimed at assessing the potential for irrigation development in Nebbi District, which cover 195,300 km2, with a view of guiding planning and strategic investment in irrigation. Irrigation potential was assessed as an aggregation of the land suitability, water requirement and the available water for irrigation for three systems (drip, sprinkler and surface). Land suitability evaluation for the three systems was determined based upon topography and soil characteristics. The FAO CROPWAT model was used to determine the water requirements for the selected crops. Water resources assessment was carried out using rainfall data and the stream flow analysis of the available water resources in the study area. For surface irrigation, no area was classified as highly suitable or moderately suitable. Only 0.03% (48.91 ha) is marginally suitable, 36% (68,445.55 ha) currently not suitable whereas 64% (121,606.33 ha) permanently not suitable. For drip irrigation, 58.7% (111,591 ha) is marginally suitable and 25.8% (49,084 ha) is moderately suitable. Furthermore, 15% (28,492 ha) and 0.5% (989 ha) are currently not suitable and permanently not suitable respectively. There was no area classified as highly suitable under drip irrigation. For sprinkler irrigation, 14.1% (26 815.8 ha) of the area is marginally suitable and 0.03% (48.1 ha) is classified as moderately suitable for sprinkler irrigation. 47.5% (90 291.4 ha) and 38.4 % (72 987.2 ha) of the area is currently not suitable and permanently not suitable respectively. The mean capability index (Ci) for surface irrigation was 36.1 (currently not suitable), 45.4 (marginally suitable) for drip irrigation while sprinkler irrigation Ci was 42.8 (marginally suitable). Crop evapotranspiration (ETc) for the selected crops (tomatoes, cabbages and onions) varied from 2.46 to 5.76 mm/day; 2.87 to 5.92 mm/day and 2.87 to 4.78 mm/day respectively. The results from water resources assessment revealed that the total catchment yield was 2.69 x 109 m3 which permits irrigation for an area of 141,817.65 ha. The results showed that drip irrigation system was more suitable for the Nebbi district.

How to cite: Kiggundu, N., Bwire, C., and Wanyama, J.: Assessment of the potential for irrigation development in Albert Nile basin: A case study of Nebbi district, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-1274, https://doi.org/10.5194/egusphere-egu2020-1274, 2020.

A decline in Lake Chad’s water level has been observed for over two decades. With millions of people relying on the lake, and considering its dynamic behavior, methods for the continuous and spatially distributed retrieval of water quantity and quality parameters are vital for proper monitoring and management initiatives. Here, we propose an integrated approach for drought, chlorophyll-a (Chl-a) and turbidity monitoring in Lake Chad using satellite datasets.

First, we used remote sensing information to constrain drought patterns over the immediate lake environment. Vegetation conditions within and around the lake was used to assess drought conditions in this area. Using Landsat multispectral images obtained between 1999 and 2018, Vegetation Temperature Condition Index (VTCI) was derived and used as an indicator for drought monitoring. Vegetation proportion from WorldView-03 images was used to evaluate the accuracy of methods used to derive VTCI. Obtained results showed that most areas experienced mild drought conditions.

Secondly, we assessed the performance of band algorithms in estimating Chl-a concentrations and turbidity levels from Landsat-8 and Sentinel-2A and 2B images. A two-band semi-analytical Chl-a and turbidity retrieval model was used for estimating the Chl-a concentrations and turbidity levels between 2015 and 2019. Due to the absence of in-situ data, estimates from the extraction models were statistically compared with datasets obtained from WorldView-03. Further inter-comparison of Chl-a and turbidity retrieved from the two sensors was carried out.

This study shows how satellite observations can be used to complement sparse and declining in situ drought, Chl-a and turbidity monitoring networks in this area. Solidifying the importance of remote sensing in areas that are difficult to access or with poor availability of conventional data sources.

How to cite: Lee, S. I. and Buma, W. G.: The Use of Landsat 8 and Sentinel-2 Time Series Data for Monitoring Drought, Chlorophyll-a and Turbidity in Lake Chad, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-1886, https://doi.org/10.5194/egusphere-egu2020-1886, 2020.

EGU2020-8214 | Displays | HS2.1.5

Nonlinear rainfall-runoff modelling of semi-arid regions using ERA5 data

James Fidal and Thomas Kjeldsen

Semi-arid regions are very challenging environments for rainfall-runoff modelling due to the high spatial variation of rainfall alongside extreme wet and dry periods resulting in distinctly different hydrological conditions within the same catchment. In order to account for the extreme wet and dry periods, a new non-linear rainfall-runoff model has been developed. The non-linear model is capable of capturing the quick recessions observed during the wet periods alongside accounting for very little flows during the dry periods. The ability of the new model was assessed by comparing the linear version with the non-linear version on two nested catchments located within South Africa. The catchments areas are 183 and 328 km2 and include 15% and 10% urbanisation respectively. The average rainfall during the wet period (May-Sep) is approximately 130mm per month with the dry period (Jan- Apr and Oct-Dec) averaging less than 35mm per month for the years 2000-2017. To challenge the problem of high spatial variation of rainfall, the fifth generation of ECMWF atmospheric reanalysis of the global climate ERA5 data is used. Both locally collected gauge and ERA5 reanalysis data were compared to show that the ERA5 data set was more capable than the local gauge in rainfall-runoff simulations with performance increases of up to 30\%. When comparing the default linear model and the non-linear model results based on ERA5 data showed the same level of performance for each model. However when flow duration curves and hydrographs were examined results showed that the linear model was not capable of adequately capturing the low flows of the catchment, whilst at the same time overestimating the high flows. Conversely, the non-linear model was capable of capturing the low flows recession and whilst it did also overestimate peak flows it was to a lesser extent than the linear model.

How to cite: Fidal, J. and Kjeldsen, T.: Nonlinear rainfall-runoff modelling of semi-arid regions using ERA5 data, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-8214, https://doi.org/10.5194/egusphere-egu2020-8214, 2020.

EGU2020-8955 | Displays | HS2.1.5

RCP 8.5 Ghana. High-end climate change impacts on crop production

Sylvia Tramberend, Günther Fischer, and Harrij van Velthuizen

Climate change threatens vulnerable communities in sub-Saharan Africa who face significant challenges for adaptation. Agriculture provides the livelihood for the majority of population. High-resolution assessments of the effects of climate change on crop production are urgently needed for targeted adaptation planning. In Ghana, next to food needs, agriculture plays an important role on international cocoa markets. To this end, we develop and apply a National Agro-Ecological Zoning system (NAEZ Ghana) to analyze the impacts of high-end (RCP8.5) global warming on agricultural production potentials until the end of this century. NAEZ Ghana uses an ensemble of the CORDEX Africa Regional Climate Model, a regional soil map, to assess development trends of crop production potentials for 19 main crops. Results highlight differential impacts across the country. Especially due to the significant increase in the number of days exceeding high-temperature thresholds, rain-fed production of several food and export crops could be reduced significantly compared to the historical 30-year average (1981-2010). Plantain production, an important food crop, could achieve under climate change less than half of its current potential already in the 2050s and less than 10% by the 2080s. Suitable areas for cocoa production decrease strongly resulting in only one third of production potential compared to today. Other crops with detrimental effects of climate change include oil palm, sugarcane, coffee, and rubber. Production of maize, sorghum, and millet cope well with a future warmer climate. The NAEZ Ghana database provides valuable high-resolution information to support agricultural sector development planning and climate change adaptation strategies. The expansion of irrigation development will play a central role in some areas. This requires further research on Ghana’s linkages between food, water, and energy, taking into account climate and socio-economic changes.

How to cite: Tramberend, S., Fischer, G., and van Velthuizen, H.: RCP 8.5 Ghana. High-end climate change impacts on crop production , EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-8955, https://doi.org/10.5194/egusphere-egu2020-8955, 2020.

EGU2020-9287 | Displays | HS2.1.5

The impact of climate change and land use/land cover change on water resources in a data-scarce catchment in Tanzania

Kristian Näschen, Bernd Diekkrüger, Mariele Evers, Britta Höllermann, Larisa S. Seregina, Stefanie Steinbach, Frank Thonfeld, and Roderick van der Linden

The Kilombero catchment is a meso-scale catchment of 40,240 km² in south central Tanzania and is characterized by overall data scarcity like many other African catchments. The catchment consists of a highly dynamic floodplain system at its centre which is sustained by water from the surrounding uplands. It also contains a Ramsar site giving evidence to its valuable ecosystem and importance concerning biodiversity conservation. However, in the last decades land use and land cover changes (LULCC) accelerated drastically towards an agriculturally-shaped landscape, especially at the fringes of the wetland. The wetland system provides fertile soils, water as well as other water-related ecosystem services. Nevertheless, the increasing pressure on natural resources jeopardizes the sustainability of the socio-ecological system, especially in the face of climate change.

 

In this study, methods of hydrology, meteorology and remote sensing were used to overcome data-scarcity and gather a sound representation of natural processes in the catchment. The Soil and Water Assessment Tool (SWAT) was applied to represent the hydrological processes in the catchment. We utilized Landsat images from several decades to simulate the impact of LULCC from the 1970s until today. Furthermore, we applied the Land Change Modeller (LCM) to simulate potential LULCC until 2030 and their impact on water resources. To account for climatic changes, a regional climate model ensemble of the Coordinated Regional Downscaling Experiment (CORDEX) Africa project was analysed and bias-corrected to investigate changes in climatic patterns until 2060, according to the RCP4.5 (representative concentration pathways) and RCP8.5 scenarios.

 

The climate change signal indicates rising temperatures, especially in the hot dry season, which reinforces the special features of this season. However, the changes in precipitation signals among the analysed RCMs vary between -8.3% and +22.5% of the annual mean values. The results of the hydrological modelling also show heterogeneous spatial patterns within the catchment area. LULCC simulation results show a 6-8% decrease in low flows for the LULCC scenarios, while high flows increase by up to 84% for combined LULCC and climate change scenarios. The effect of climate change is more pronounced compared to the effect of LULCC, but also contains higher uncertainties. This study exemplarily quantifies the impact of LULCC and climate change in a data-scarce catchment and therefore contributes to the sustainable management of the investigated catchment, as it shows the impact of environmental change on hydrological extremes and determines hot spots, which are crucial for more detailed analyses like hydrodynamic modelling. The information from this study are an essential part to assist local stakeholders protecting the wetlands integrity on the one hand and to ensure sustainable agricultural practices in order to guarantee food security on the other hand in a catchment that has already changed tremendously and is still target to manifold future plans.

How to cite: Näschen, K., Diekkrüger, B., Evers, M., Höllermann, B., Seregina, L. S., Steinbach, S., Thonfeld, F., and van der Linden, R.: The impact of climate change and land use/land cover change on water resources in a data-scarce catchment in Tanzania, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-9287, https://doi.org/10.5194/egusphere-egu2020-9287, 2020.

EGU2020-10389 | Displays | HS2.1.5

Land Surface Temperature and Miombo forest canopy phenophases: what induces leaf fall and leaf flush?

Henry Zimba, Miriam Coenders-Gerrits, Banda Kawawa, Imasiku Nyambe, Hubert Savenije, and Hessel Winsemius

Miombo woodland is the most widespread tropical seasonal woodland and dry forest formation in Africa covering between 2.7 and 3.6 million km2 in eleven countries. Leaf fall and leaf flush during the dry season is a major characteristic feature of the various Miombo species. However, the question on what induces the leaf fall process is by far inconclusive. Different studies indicate either moisture or temperature or both elements as inducers for leaf fall. Knowing what induces leaf fall is important for studying the consequence of e.g., climate change on the Miombo forest. To better understand the driver of leaf fall in Miombo forest we employed a simple remote sensing and statistical analysis approach using long term averages (2009 – 2018) of Land Surface Temperature (LST) of the Miombo forest, various vegetation indices (VI), actual evaporation (Ea), and root zone soil moisture (SM). The vegetation indices (VI) included the Normalised Difference Water Index (NDWI) as indicator of vegetation water content and the Normalised Difference Vegetation Index (NDVI) as indicator of plant photosynthetic activities and leaf cover. Results showed that the NDWI, NDVI, Ea and SM begun to decline immediately following the end of the rainy season in early April while the LST remained relatively constant before it began to decline in May when leaf fall in some Miombo species begins. Hysteresis graphs revealed that vegetation water content (i.e. NDWI) responded quicker to changes in both LST and SM. Furthermore, high rates of decrease in NDWI and NDVI values were observed between July and September the same period when LST increased. This is also the same period when leaf fall intensifies in Miombo forest. Correlation analysis revealed strong season-dependent LST relationship with VI and SM with the rainy season exhibiting strong negative linear correlations (R2 = 0.77, 0.91, 0.88; for the NDWI, NDVI and SM respectively). In the dry season relatively weaker negative correlations (R2 = 0.52, 0.60, 0.55; for NDWI, NDVI and SM respectively) were observed. On the other hand SM showed strong positive linear correlations (R2 > 0.6) with NDWI and NDVI (for the rainy and dry seasons respectively). The correlations imply that in Miombo forest soil water content (i.e. SM), vegetation water content (i.e. NDWI) and the photosynthetic activities and leaf cover (i.e. NDVI) declines with increase in LST. These relationships show the possibility of land surface temperature being a major inducing element of leaf fall and changes in canopy structure in the Miombo woodland.

How to cite: Zimba, H., Coenders-Gerrits, M., Kawawa, B., Nyambe, I., Savenije, H., and Winsemius, H.: Land Surface Temperature and Miombo forest canopy phenophases: what induces leaf fall and leaf flush? , EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-10389, https://doi.org/10.5194/egusphere-egu2020-10389, 2020.

EGU2020-11877 | Displays | HS2.1.5

Evaluation of precipitation and actual evaporation products over the Nile Basin

Oscar M. Baez-Villanueva, Ian McNamara, Mauricio Zambrano-Bigiarini, and Lars Ribbe

An improved representation of the spatio-temporal patterns of climatological variables is crucial for ecological, agricultural, and hydrological applications and can improve the decision-making process. Traditionally, precipitation (P) and actual evaporation (ETa) are estimated using ground-based measurements from meteorological stations. However, the estimation of spatial patterns derived solely from point-based measurements is subject to large uncertainties, particularly in data-scarce regions as the Nile Basin, which has an area of about 3 million km2. This study evaluates six state-of-the-art P products (CHIRPSv2, CMORPHv1, CRU TS4.02, MSWEPv2.2, PERSIANN-CDR and GPCCv2018) and five ETa products (SSEBop, MOD16-ET, WaPOR, GLEAM and GLDAS) over the Nile Basin to identify the best-performing products. The P products were evaluated at monthly and annual temporal scales (from 1983 onwards) through a point-to-pixel approach using the modified Kling-Gupta Efficiency and its components (linear correlation, bias, and variability ratio) as continuous performance indices. The ETa products were evaluated through the water balance approach (due to the lack of ground-based ETa measurements) for 2009-2018 at the multiannual scale. Because streamflow data were not available for this period, an empirical model based on the Random Forest machine learning technique was used to estimate streamflow at 21 catchments at the monthly scale. For this purpose, we used streamflow data from 1983 to 2005 as the dependent variable, while CHIRPSv2 precipitation and ERA5 potential evaporation and temperature data were used as predictors. For the catchments where the model performed well over the validation period, streamflow estimates were generated and used for the water balance analysis. Our results show that CHIRPSv2 was the best performing P product at monthly and annual scale when compared with ground-based measurements, while WaPOR was the best-performing ETa product in the water balance evaluation. This study demonstrates how remote sensing data can be evaluated over extremely data-scarce scenarios to estimate the magnitude of key meteorological variables, yet also highlights the importance of improving data availability so that the characterisation of these variables can be further evaluated and improved.

How to cite: Baez-Villanueva, O. M., McNamara, I., Zambrano-Bigiarini, M., and Ribbe, L.: Evaluation of precipitation and actual evaporation products over the Nile Basin, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-11877, https://doi.org/10.5194/egusphere-egu2020-11877, 2020.

EGU2020-17163 | Displays | HS2.1.5

The sensitivity of a critical zone model to the representation of hydraulic conductivity heterogeneity in a deeply weathered hard rock aquifer in West Africa

Amelie Herzog, Basile Hector, Jean-Martial Cohard, Fabrice-Messan Lawson, Jean-Michel Vouillamoz, and Inge de Graaf

Currently 40 % of Africa's population still lacks access to clean water. Twice as many rural people live in hard rock areas as compared to sedimentary areas. In these hard rock areas a thick weathered regolith layer covers the crystalline basement, where groundwater (GW) circulates. In the Sudanian area of West Africa (WA) ,groundwater levels are shallow enough to interact directly with the surface water. Therefore, constructing coupled surface-groundwater models helps to estimate quantities of both, GW and surface flows, and their evolution over time to facilitate integrated water management. However, the sensitivity of such models to aquifer properties (saturated hydraulic conductivity (Ks), porosity, geometry), which are difficult to obtain in heterogeneous crystalline contexts, is still poorly constrained. The heterogeneity of aquifer properties at the scale at which most water management decisions are taken, is twofold: 1) bimodal vertical heterogeneity with an unconsolidated weathered zone (high porosity, low Ks) overlying a fissured zone (low porosity, high Ks) and 2) lateral heterogeneity controlled by substratum features and weathering history. We assessed the sensitivity of a coupled surface-groundwater model (PARFLOW-CLM) to vertical and lateral heterogeneity of Ks. The sensitivity to the lateral heterogeneity was explored either using simulations with homogeneous or distributed Ks following random field approaches with a range of spatial correlation lengths. The representation of a vertically uniform aquifer layer was compared to a two-layer scenario for each of the lateral heterogeneity cases. Here, we focused our analysis on the Northern Oueme catchment in Benin (14 000 km²) and we constructed a model with a spatial resolution of 1 km², preventing the analysis of smaller-scale features, such as macropores or clay accumulations. Hydraulic conductivity and aquifer geometry data to constrain the sensitivity experiments were derived from the literature specific to the target area, but also from regional hard rock aquifers in West Africa. As an output of the model, we obtained streamflow, water table head and evapotranspiration time series (in a monthly and daily resolution). The results that we gained with our model configuration (and resolution) point towards a low sensitivity of the model to lateral and vertical heterogeneity. However, we observed a significant impact of the magnitude of Ks on water table head and particularly on the streamflow amplitude. Regarding the water balance our results show that further exploration of the subsurface is crucial to improve critical zone modeling in the context of WA.

How to cite: Herzog, A., Hector, B., Cohard, J.-M., Lawson, F.-M., Vouillamoz, J.-M., and de Graaf, I.: The sensitivity of a critical zone model to the representation of hydraulic conductivity heterogeneity in a deeply weathered hard rock aquifer in West Africa, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-17163, https://doi.org/10.5194/egusphere-egu2020-17163, 2020.

EGU2020-18552 | Displays | HS2.1.5

A physically-based ensemble of high-resolution regional climate simulations for Sub-Saharan Africa

Patrick Laux, Diarra Dieng, Tanja Portele, Joel Arnault, Christof Lorenz, Jan Bliefernicht, and Harald Kunstmann

There is an increasing demand for sound climate information in Sub-Saharan Africa (SSA) for both regional and local scales. While climate information from Global Climate Models (GCMs) are usually too coarse for climate impact modelers or decision makers from various disciplines (e.g. hydrology and water management, agriculture, energy), Earth System Models (ESMs) provide feasible solutions for downscaling GCM output to required spatiotemporal scales. However, it is well known that the performance of regional simulations depends a lot on the physical parametrization, which may vary from region to region. Besides land-surface processes, the most crucial processes to be parameterized in ESMs include radiation, convection, and cloud microphysics, partly with complex interactions. Precipitation generation, for instance, involves many coupled processes between cumulus convection, cloud microphysics, radiation, land and ocean surface, and the planetary boundary layer. Before conducting long-term ESM simulations, it is therefore indispensable to identify a suitable physics parametrization combination. Based on the European Centre for Medium-Range Weather Forecasts (ECMWF) reanalysis product ERA-Interim, we performed a set of 16 high-resolution physics parameterization experiments for SSA, using different cumulus-, microphysics-, planetary boundary layer-, and radiation schemes in the Weather Research and Forecasting (WRF) model for the period 2006-2010 in a spatial resolution of 9 km. Based on traditional (Taylor diagram, probability densities) and more innovative validation metrics (ensemble structure–amplitude–location (eSAL) analysis, Copula functions) and with the use of various observation data for precipitation and temperature, favorable parameterization combinations for whole SSA are identified and will be discussed also w.r.t. the required computing time. Here, we find that complex radiation schemes do not urgently lead to better simulation results for SSA, but increase the computing time tremendously.           

How to cite: Laux, P., Dieng, D., Portele, T., Arnault, J., Lorenz, C., Bliefernicht, J., and Kunstmann, H.: A physically-based ensemble of high-resolution regional climate simulations for Sub-Saharan Africa, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-18552, https://doi.org/10.5194/egusphere-egu2020-18552, 2020.

EGU2020-19020 | Displays | HS2.1.5

Investigation of the Green-Ampt infiltration model in rainfall-runoff simulations with a robust 2D shallow water model

Franziska Tügel, Aziz Hassan, Manal Wannous, Uwe Tröger, and Reinhard Hinkelmann

The Green-Ampt model was developed more than 100 years ago and is still one of the most commonly used approaches to consider infiltration in rainfall-runoff models, which can be either conceptual catchment models as well as 2D hydrodynamic models. When coupling, for example, the Green-Ampt model for infiltration with a 2D shallow water model for the flow, the calculated ponding water depths are transferred from the flow model to the Green-Ampt model to calculate the infiltration rates, and the resulting infiltration rates represent then sinks in the mass balance equation of the shallow water model. The so-called Green-Ampt parameters in terms of saturated water content, hydraulic conductivity, and suction head at the wetting front, are needed as model input in addition to the initial water content. Often, the Green-Ampt parameters are not directly measured in the field for the area that should be modeled but are only assumed based on average values from the literature depending on the dominant soil texture class. If reliable data of certain rainfall-runoff events are available for the study area, the values of the Green-Ampt parameters can be determined besides other calibration parameters within reasonable ranges. However, in some cases, a calibration of the Green-Ampt parameters is not possible due to a lack of measurements, for example during suddenly occurring flash floods or in completely ungauged basins. This study aims to investigate with a coupled shallow water flow and infiltration model if the Green-Ampt parameters could be appropriately assumed based on average values from literature depending on the given soil texture classes. Furthermore, the effects that could lead to an inappropriate representation of infiltration with tabulated Green-Ampt parameters are studied, such as surface clogging, sub-grid rill-flow, and coarse DEM resolution. To investigate the general suitability of using average Green-Ampt parameters from literature dependent on soil texture classes, different small-scale test cases with available data for calibration are shown, where two of them are laboratory experiments and one is a rainfall-runoff experiment on a small plot in Senegal. Finally, a case study on flash floods in a desert region in Egypt is represented. The results show that in the laboratory experiments, the infiltration rates with average Green-Ampt parameters are underestimated, while for the field experiment in Senegal infiltration rates are overestimated. For the case study in Egypt, infiltration with Green-Ampt parameters from literature as well as with measured infiltration rates from double ring infiltrometer tests is strongly overestimated in the model. It is planned to conduct plot-scale rainfall-runoff experiments with a rainfall simulator for the study area in Egypt to better represent the natural conditions during heavy rainfalls and compare the measured infiltration rates with the ones from literature and double ring infiltrometer test.

How to cite: Tügel, F., Hassan, A., Wannous, M., Tröger, U., and Hinkelmann, R.: Investigation of the Green-Ampt infiltration model in rainfall-runoff simulations with a robust 2D shallow water model, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-19020, https://doi.org/10.5194/egusphere-egu2020-19020, 2020.

EGU2020-20634 | Displays | HS2.1.5 | Highlight

Environmental impacts of diamond mining in the Democratic Republic of Congo

Nikolas Galli, Davide Danilo Chiarelli, Manuel D'Angelo, and Maria Cristina Rulli

The mining industry of the Democratic Republic of the Congo represents the most important sector of the country’s economy being DRC the second-largest diamond-producer in the world. By far the largest diamond-mines in the DRC are located in southern Katanga province.

There are many types of mining techniques and alluvial mining is the one that usually takes place in DRC.

Alluvial diamonds are diamonds that have been removed from the primary source (Kimberlite) by natural erosion, and eventually deposited in a new environment such as a river beds and floodplains. This type of mining leads obviously to a number of impacts: deforestation, river pollution, water resources exploitation, unhealthy, unregulated and sometimes dangerous environments in which diggers work.. All these effects are strictly related and difficult to evaluate since the DRC is in a situation of institutional chaos and humanitarian crisis due to high rate of malnutrition.

Here we analyze the impact of diamond mining industry on natural resources, and population in Democratic Republic of Congo. To this end using spatial and temporal high resolution data we evaluate the tree cover losses and the water resources use associated with mining activity from 2000 to 2018 and using a dynamic and spatially distributed crop water model we provide alternative use of natural resources (i.e. land and water) presently used for mining so assessing the likelihood to contrast malnourishment.

How to cite: Galli, N., Chiarelli, D. D., D'Angelo, M., and Rulli, M. C.: Environmental impacts of diamond mining in the Democratic Republic of Congo, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-20634, https://doi.org/10.5194/egusphere-egu2020-20634, 2020.

EGU2020-20682 | Displays | HS2.1.5

Future water availability in West Africa: Estimates from high-resolution RCM modeling and multivariate bias correction

Diarra Dieng, Cornelius Hald, Patrick Laux, Christof Lorenz, and Harald Kunstmann

Future water availability in West Africa: Estimates from high-resolution RCM modeling and multivariate bias correction

Diarra Dieng1, Cornelius Hald1, Patrick Laux1,2, Christof Lorenz1, Harald Kunstmann1,2

1Institute of Meteorology and Climate Research (IMK-IFU), Campus Alpine, Karlsruhe Institute of Technology (KIT), Karlsruhe, Germany,

2Institute of Geography, University of Augsburg, Augsburg, Germany,

 

With a wide range of ecological, climatic, and cultural diversities, West Africa is a rapidly developing region whose agricultural systems remain largely rain-fed and underdeveloped. In this study we examine the potential impacts of climate variability and climate change on the water availability in the mid-21st century in West 
Africa by using high resolution simulations (12km) from the Weather and Research Forecasting (WRF) model and the COSMO-Climate Limited area Modelling (CCLM) for the RCP 4.5 scenario. Our approach is based on the simplified Penman-Monteith (PM) equation for daily ET, which requires the joint information on relative humidity, maximum and minimum daily temperatures, dew point temperature, solar radiation and wind speed. It is not only crucial that the statistical behavior of these modelled variables is close to observations, but also that the interplay between these variables is realistic. We therefore further adapted, applied and analyzed a subsequent bias-correction method for the WRF and CCLM simulations using a nonparametric, trend-preserving quantile mapping approach and a multivariate bias correction approach (MBCn). We present the details of the method and the derived implications for expected water availability in West Africa.

How to cite: Dieng, D., Hald, C., Laux, P., Lorenz, C., and Kunstmann, H.: Future water availability in West Africa: Estimates from high-resolution RCM modeling and multivariate bias correction , EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-20682, https://doi.org/10.5194/egusphere-egu2020-20682, 2020.

HS2.1.6 – Forest and tropical hydrology

Understanding of plant water uptake and ecohydrological interactions between plants and soil water is crucial for developing effective and sustainable water use strategies, in particular for agricultural areas. To explore these questions, isotopic analyses of plant and source water provide useful tools alongside traditional techniques. Although such studies in tropical regions are less abundant, recent meta-analyses have revealed that vegetation water generally resembles that of deeper soil water sources than in temperate and cold climate regions. However, water uptake patterns from different sources can also vary in time, especially in the tropics where seasonality in precipitation and associated water availability is strong. As the distinct wet and dry seasons are expected to become more intense, this can have important implications for ecosystems and agriculture.

This presentation will bring together results from recent isotope studies on plant-soil-water interactions in tropical climate regions across the world. In particular, it will focus on system changes at the extreme ends of hydroclimatological conditions. It will also explore the implications this might have for agriculture, e.g. in terms of the sustainability of agroforestry where competition for water between co-existing vegetation might increase during dry periods, and how additional irrigation or flooding from extreme rainfall can change runoff dynamics and recharge leading to enhanced leaching of pollutants.

How to cite: Geris, J.: Plant-soil-water interactions in the tropics: using isotopes to explore environmental change implications for agriculture, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-18733, https://doi.org/10.5194/egusphere-egu2020-18733, 2020.

Climate change and unsustainable land use practices such as quarrying have the potential to negatively impact the hydrology and water resource availability in catchments. Throughout the Caribbean, hillside quarrying has become a common practice. While these activities remove large sections of the critical zone, very little work has been done on how hillside quarrying impacts storm response and catchment water storage.  The study is particularly important given the expected changes to rainfall patterns in the Caribbean under future climate change. We hypothesised that the removal of the critical zone during quarrying will increase the magnitude of streamflow response to storm events due to its close proximity to the river, while also reducing the overall storage of the watershed. This study utilized a hydrometric and geochemical approach with direct measurements of rainfall and streamflow, and bi-weekly water sample collections for geochemistry and 18O and 2H stable isotopes between the 3.6 km2 Acono (forested) and the adjacent 3.6 km2 Don Juan (quarried) watersheds, located in Trinidad and Tobago. A total of 1207 mm of rainfall occurred, with 87.3% falling from August to November (wet season) and 12.7% from December to March (dry season). The δ 18O in rainfall ranged from -7.7 to 0.3 ‰ across both seasons with an average δ18O of -3.5±1.8‰ during the wet season and 0.1±0.5‰ in the dry season. During the dry season the mean δ 18O of stream water showed a difference between the forested (-2.8±0.3‰) and quarried (-3.1±0.3‰) catchments whereas there was little differences in δ18O in the forested catchment (-3.3±0.3 ‰) and quarried catchment–(-3.2±0.27‰) in the wet season. Our stream δ18O dry season results suggests that different sources of water or anthropogenic influences such as water from settling ponds in the quarry could have impacted the δ18O of the quarried stream as we expected the forested catchment to be more stable. Sample collection at these sites is ongoing and additional parameters such as soil water isotopes and rainfall, soil and stream ion chemistry are expected to improve our understanding of the translation from rainfall to streamflow. This research will allow us to gain a better insight of the current hydrological processes within this catchment and aid in the long term adaptive planning for factors such as climate change and further land use change.

 

How to cite: Mathura, N. and Farrick, K.: Analyzing Land Use Impacts on Streamflow Response in a Tropical Watershed: A Hydrometric and Geochemical Approach, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-1211, https://doi.org/10.5194/egusphere-egu2020-1211, 2020.

EGU2020-8303 | Displays | HS2.1.6

Flood severity along the Usumacinta River, Mexico: identifying the anthropogenic signature of tropical forest conversion.

Alexander Horton, Anja Nygren, Miguel Diaz-Perera, and Matti Kummu

Global climate change and anthropogenic activities are disrupting flood frequency-magnitude distributions along many of the world’s large rivers, posing critical threats to rising populations and infrastructure. Isolating a single discharge signal amidst the multitudes of competing anthropogenic signatures is a persistent, yet important challenge if we are to mitigate against their negative consequences. The Usumacinta River in southern Mexico provides an ideal opportunity to study an anthropogenic driver in isolation: tropical forest conversion. The Usumacinta flows unobstructed along the entirety of its course, meaning the 55-year discharge record (1959 – 2014) represents the river’s response to a changing landscape under climatic variability. This paper employs a novel approach to disentangle the anthropogenic signal from climate variability, and provides valuable insight into the impact of forest conversion on flood severity.

Here we analyse continuous daily time series of precipitation, temperature, and discharge to identify long-term trends, and compare ratios of catchment-wide precipitation totals to daily discharges in order to account for climatic variability, and identify an anthropogenic signature of tropical forest conversion at the intra-annual scale. We successfully reproduce this signal using a distributed hydrological model (VMOD), and demonstrate that the continued conversion of tropical forest to agricultural land will further exacerbate large scale flooding.

We find statistically significant increasing trends in annual minimum, mean, and maximum discharges that are not evident in either precipitation or temperature records. We also find that mean monthly discharges have increased between 7 and 75% in the past decade, in contrast to mean monthly precipitation, which has decreased during the dry-season. Model results demonstrate that forest cover loss is responsible for raising the 10-year return flood by 20%, and the total conversion of forest to agricultural land may result in an additional 23% rise. Meaning the return period for a flood on the order of the 2008 peak discharge would fall from the current estimate of 41 years to just 12 under the total forest conversion scenario.

These findings highlight the need for a holistic approach to catchment-wide land management in developing tropical regions that weights the benefits of agricultural expansion against the consequences of increased flood prevalence, and the economic and social costs that they incur.

How to cite: Horton, A., Nygren, A., Diaz-Perera, M., and Kummu, M.: Flood severity along the Usumacinta River, Mexico: identifying the anthropogenic signature of tropical forest conversion., EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-8303, https://doi.org/10.5194/egusphere-egu2020-8303, 2020.

EGU2020-14092 | Displays | HS2.1.6 | Highlight

Investigating blue water response to green management in a Mediterranean headwater catchment

Jérôme Latron, Mariano Moreno de las Heras, Antonio Molina, Francesc Gallart, Teresa Cervera, Teresa Baiges, Joaquim Garcia, Gabriel Borràs, Antoni Munné, Andreu Manzano, Miquel De Cáceres, and Pilar Llorens

Although forest provides multiple ecosystem services (e.g., soil conservation, carbon sequestration, regulation of water cycle), it often cannot provide all of them simultaneously because of the trade-offs between some of them. In particular, while afforestation and reforestation have been recommended as a means of sequestering carbon in forest biomass and soils to limit climate change impacts, these practices may significantly alter streamflow and groundwater recharge, particularly in Mediterranean headwater catchments. In this context, a better understanding of forest hydrology is necessary to anticipate the undesirable trade-offs of forest management that can affect water resources.

Within the MASCC and LIFE + CLIMARK projects, which respectively aim to establish possible land cover scenarios for the next decades and to implement forest management practices to strengthen the capacity of the forest to mitigate the effects of change climate, the Vallcebre research catchments (North Eastern Spain) were selected as a reference site to assess the effect of forest (green) management on water resources (blue water) in a Mediterranean environment. These research catchments offer available medium-term (15 years) hydrological series (precipitation, discharge and water table) prior to forest management and a detailed knowledge of their hydrological response, essential for this evaluation.

In October 2018, the forest cover of a small sub-catchment (0.0248 km2) which initially represented 54% of the basin was thinned (removing between 35% and 60% of the basal area depending on the locations) to assess the effect of multifunctional forest management on streamflow. In the same way, the forest covering the contribution areas (0.0138 and 0.0139km2) of two shallow piezometers was thinned according to the same procedure to evaluate possible changes on the dynamics of the piezometric levels.

This work aims to present the general framework of the study, the type of forest management carried out as well as a first analysis (at different temporal scales) of the water table and discharge dynamics observed during the first year after the forest management.

How to cite: Latron, J., Moreno de las Heras, M., Molina, A., Gallart, F., Cervera, T., Baiges, T., Garcia, J., Borràs, G., Munné, A., Manzano, A., De Cáceres, M., and Llorens, P.: Investigating blue water response to green management in a Mediterranean headwater catchment, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-14092, https://doi.org/10.5194/egusphere-egu2020-14092, 2020.

EGU2020-19167 | Displays | HS2.1.6 | Highlight

The 2018 drought and its consequences: Investigating the resilience of different tree species based on comprehensive long-term monitoring of forest hydrology

Theresa Blume, Daniel Balanzategui, Lisa Schneider, Daniel Rasche, Markus Morgner, Andreas Güntner, and Ingo Heinrich

Many forests in Central Europe experienced unprecedented drought conditions in 2018. The exceptionally long dry period, lasting from early-summer 2018 and into the winter, was followed by another dry summer with record-breaking temperatures.   Ecohydrological consequences of extended droughts for these temperate forest systems are difficult to anticipate, and investigating the resilience of forest hydrological systems requires comprehensive and systematic long-term observations.

Monitoring at the TERENO-NE temperate forest observatory in northeastern Germany includes input characterization (throughfall and stemflow), high-resolution soil moisture observations in 14 different forest stands down to a depth of 2 m below the soil surface, shallow and deep groundwater observations, sap flow, tree water deficit and high-resolution tree growth measurements since 2012. The investigated forest stands cover the three tree species pine, oak and beech in both pure and mixed stands. This is complemented by terrestrial gravimetric measurements of total water storage changes. Steep hillslope transects allow us to investigate the impact of presence or absence of groundwater availability on tree water uptake and growth.

We find that after the unprecedented drought in 2018, which already had pronounced ecohydrological effects, the rainfall amounts over the winter 2018/19 were insufficient to refill the subsurface water storages. Dry conditions altered the growth phenology of each monitored tree species, while tree-water deficit and tree growth were negatively impacted in both years, but to varying extent. Soil moisture storage and dynamics are strongly affected and the drought caused a long-term memory effect.

How to cite: Blume, T., Balanzategui, D., Schneider, L., Rasche, D., Morgner, M., Güntner, A., and Heinrich, I.: The 2018 drought and its consequences: Investigating the resilience of different tree species based on comprehensive long-term monitoring of forest hydrology, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-19167, https://doi.org/10.5194/egusphere-egu2020-19167, 2020.

Human activities have had a dramatic impact on the forest ecosystem, which has changed from initial overexploitation to the current regional restoration. Such kind of human interference with forest ecosystem aggravates the uncertainty on regional hydrology in the contest of global climate change. Here we analyze the hydrology variation over 30 years in Daqing River Basin covered by the ecological restoration project, North China. We identified the influence of climate and human disturbance (ecological restoration project) on surface runoff and soil water. In addition, combined with the future plan of ecological restoration projects in the upper reaches and Xiong’an New Central Area construction in the lower reaches, regional hydrological effects and water demand gaps in the lower reaches under different restoration scenarios were analyzed. The results showed that since 1980's, the surface and soil water in Daqing River Basin had a sudden change in 1999, and the influence of human interference after the change was significantly higher than before, among which the influence of forest area and quality was the dominant contributors. The results of the scenario analysis show that under the existing regional ecological restoration projects and climate change trends, there will be about 1/6 water resource gap in the lower reaches of the basin by 2050, of which about 35% will be caused by ecological projects. Our research results show that changes in forest area and quality brought about by basin-level ecological restoration projects will significantly increase upstream evaporation and water conservation, thereby affecting the regional hydrological cycle and aggravating the conflict between supply and demand of water resources downstream.

How to cite: Li, R., Zheng, H., Pan, Y., and Lu, F.: Hydrological effects triggered by large-scale forest restoration in catchment scale, a case study in Daqing River Basin, North China, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-21661, https://doi.org/10.5194/egusphere-egu2020-21661, 2020.

A widely accepted approach in both conceptual and numerical models of groundwater flow is to assume that the water table (WT) is a subdued replica of topography, where groundwater recharges at topographic highs and discharges at topographic lows. However, WTs in low-relief, water-limited environments are generally not topographically controlled, therefore traditional paradigms where forested hummocks are sources of water to both adjacent local wetland-pond systems and catchment-scale runoff do not usually hold true. Local groundwater flow systems (flow in which the recharge area is directly adjacent to its discharge area) are necessary to link forested hummocks with adjacent peatlands or ponds. However, the development of the groundwater mounds beneath topographic highs required to generate local groundwater flow systems is both spatially and temporally infrequent in low-recharge settings like the Boreal Plains. Thus, identifying the spatiotemporal controls on groundwater mounding is crucial to understanding the climatic and geological conditions required for landscape connectivity and runoff generation at larger, regional scales. This insight is becoming increasingly important as water security, ecosystem sustainability, and environmental quality become the focus of land management and reclamation efforts.

The Canadian Boreal Plains are dominated by aspen mixedwood forests, shallow lakes, and peatlands, and has a sub-humid climate that causes large interannual variability in runoff generation and hydrological connectivity at the landscape scale. Through a combination of field observations and numerical modelling, this study identifies the role of aspen forested hummocks in the generation (or loss) of groundwater and hydrologic connectivity to adjacent peatlands and lakes. WT elevations and climate data (precipitation (P) and potential evapotranspiration (PET)) collected over the last 20 years at nine fine-textured forested hummocks were examined for frequency and magnitude of groundwater mounding and/or depressions relative to their adjacent peatlands. It was evident that no simple metric (e.g., annual P, multiyear cumulative P-PET, etc.) was a good predictor for WT position. Through a combination of 1D and 2D, variably saturated numerical modelling, we identify the relative spatiotemporal controls that hummock morphometry, texture, and climate have on groundwater recharge and WT position. Multiple scales of climate forcings (seasonal, interannual; P, PET), substrate texture, hummock height, and rooting parameters all affect groundwater recharge (both positive and negative). Groundwater recharge is most dependent on timing and magnitude of snow melt; however, during periods of large interannual moisture surplus, when available subsurface storage is low, large summer and fall storms can also contribute to recharge. Otherwise, the overwhelming majority of scenarios result in hummocks storing and transpiring water and receiving inputs of groundwater from neighboring peatlands, therefore acting as a net sink of water to the larger landscape.

We show that groundwater mounds, and therfore the development of local topographic flow systems, under forested hummocks are spatiotemporally rare in sub-humid, low-relief regions, resulting in these hummocks being net sinks of water. Not only does this study emphasize the role of peatlands in the generation of landscape-scale runoff, it encourages a reconceptualiztion of the overall hydrologic function of forestlands and peatlands in catchment hydrology.

How to cite: Hokanson, K., Devito, K., and Mendoza, C.: The give and take (but mostly take) of forested boreal plains hummocks: Are they hydrologic sources or sinks?, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-107, https://doi.org/10.5194/egusphere-egu2020-107, 2020.

EGU2020-155 | Displays | HS2.1.6

Coupled hydrology - routing model to improve hydrogeological and hydraulic data across a tropical basin in Colombia

Maria Arenas, Pedro Felipe Arboleda Obando, and Leonardo David Donado Garzón

Hydrologic models allow to simulate the water fluxes and storages inside a watershed, and so, to compute the water budget at different time and spatial scales. Even if they are important tools for water management, uncertainty can affect their results. The output data of the hydrologic model can be used to run other models, i.e, a hydrogeologic model (which needs recharge data) and hydrodynamic models (which need discharge data for some tributaries with no gauge stations). Therefore, with the scope to reduce uncertainty and to achieve a better representation in tropical basin systems, we focus on building a coupled hydrology model able to simulate data to be used inside of groundwater flow and surface water hydrodynamic models.  In order to do so, we decided to use Dynamic Topmodel, a recent development from the well – known Topmodel, as the hydrologic module, through the HRU (hydrological response units) approach to split the area in smaller units. Then, to include the routing processes, we decided to couple Dynamic Topmodel to the Variable Infiltration Capacity model 2D routing module (VIC-2D), to represent the drainage network using cells, and simulate discharge values at some non-gauged locations. The coupling was built under one single main hypothesis: all the cells inside a single HRU will produce the same recharge and runoff value. Based on this hypothesis we built the input data maps to run the routing module.

 

As our case study, we chose a 31 140 km2 basin in the Middle Magdalena Valley (MMV), a central area with important economic activities, as oil and gas (O&G) exploration and production, agriculture and livestock. Our model used cells of size 3 km with 76 HRU, but only seven parameter sets, so many of those 76 HRU shared parameter values, according to the digital elevation model (DEM), soil texture, and land used data. Our analysis is grounded on a record of 30 years of hydro-meteorological variables. The results of the coupling model described in a satisfactory way the following outcomes: (i) the fluxes among hydrosystems, (ii) channel flows, (iii) optimizing the computational performance (budget) of models in basins of tropical regions and (iv) allowing identification of trends on the discharge across the area to support the calibration of hydrodynamic models. In addition, the developed technique reduces the uncertainty of the model outcomes in areas with no data.

How to cite: Arenas, M., Arboleda Obando, P. F., and Donado Garzón, L. D.: Coupled hydrology - routing model to improve hydrogeological and hydraulic data across a tropical basin in Colombia, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-155, https://doi.org/10.5194/egusphere-egu2020-155, 2020.

EGU2020-588 | Displays | HS2.1.6

Simulation of sub-basin sediment yields and river runoffs into Davao Gulf, Philippines

Adonis Gallentes, Peter Jeffrey Maloles, and Cesar Villanoy

The Philippines is a country within the Coral Triangle which is known to be the center of the most biologically diverse marine ecosystem in the world. Despite being a crucial area for marine biodiversity, discharge measurements of many rivers in the country are either sparse or non-existent. Such data are important in assessing aspects such as sedimentation which is highly related to the health of the reef community.

Here, we applied SWAT hydrological model in order to simulate the sediment yield of sub-basins and river discharge surrounding Davao Gulf, one of the country’s richest zones in terms of fish production. Monthly-averaged results of the model from 2001 to 2018 indicate that the relative maxima of sediment yield coincide with precipitation maxima, and that consecutive rainfall events which start around midyear results to higher erodibility and thus, higher peaks in sediment yield during the second half of each year until the early part of the following year. Dependence of sediment yield on slope class/angle and land use was also observed, identifying the northwestern catchments as critical sources of land surface erosion. Good agreement was obtained between simulations of river discharge and the sparse observed streamflow values during model validation (Davao River: NSE=0.61, R2=0.61, PBIAS = 2.87, r= 0.78; Hijo River: NSE=0.62, R2=0.90, PBIAS = -2.1630, r= 0.95).

Overall, this modeling study helped fill in the temporal gaps of observed streamflow data from river gauges, and provided estimates of the historical streamflow pattern of those rivers with no river gauges. Outputs of this study can also be used as science-based reference in crafting laws and ordinances for proper land use and Marine Protected Area (MPA) management plans, with emphasized consideration of the likely effects of climate change such as the latitudinal shift of typhoon tracks, increasing temperature, and more pronounced precipitation events which have already been observed in the area during the past two decades. 

How to cite: Gallentes, A., Maloles, P. J., and Villanoy, C.: Simulation of sub-basin sediment yields and river runoffs into Davao Gulf, Philippines, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-588, https://doi.org/10.5194/egusphere-egu2020-588, 2020.

EGU2020-5670 | Displays | HS2.1.6

Improving reference evapotranspiration (ETo) calculation under limited data conditions in the Tropical Andes

Cristina Vásquez, Mario Córdova, Galo Carrillo, and Rolando Célleri

The correct determination of reference evapotranspiration (ETo) is fundamental for countless scientific and management applications such as closing the catchment water balance, the planning of irrigation schemes, and for simulation models. Nevertheless, the records of weather variables are often not available or incomplete. This usually happens when a sensor breaks or malfunctions due to severe weather conditions, lack of maintenance or electronic failure, which leads to data loss and consequently makes it hard to estimate ETo. Frequently, that is the case in mountain regions where meteorological sensors are subject to harsh environmental conditions as in the Andes. In case of missing data, the only solution is to estimate the required variable using a given equation. Therefore, these equations need to be calibrated to specific local conditions. The aim of this study was to calibrate and validate equations to estimate Solar Radiation (Rs) on daily and monthly scales and to evaluate the impact of using these estimations for the calculation of ETo through the Penman Monteith (PM) equation in an Andean altitudinal gradient in the páramo ecosystem. The páramo occupies the upper portion of the northern Andes, where the tussock grasslands are the dominant vegetation. In addition, this ecosystem provides essential environmental services for inter-Andean cities. We used six years of observations (2013–2019) from the Quinoas Ecohydrological Observatory. This Observatory has four meteorological stations: Toreadora (3955 m a.s.l), Virgen Cajas (3626 m a.s.l), Chirimachay (3298 m a.s.l) and Balzay (2610 m a.s.l). We evaluated five models to estimate Rs based on the maximum and minimum daily air temperature. A calibration was performed for each weather station and a simultaneous calibration for the entire gradient. We used four years of data for calibration and validation of the Rs model, and two years to evaluate the impact on ETo calculations. We found that all models yielded estimations that are highly correlated with the observed data. However, no model was able to capture high Rs values, greater than 185.4 W m-2 (16 MJ m-2 d-1), found in cloud-free days. The best model to estimate Rs was the locally calibrated Chen model, which showed a mean error of 2.9 W m-2 (0.25 MJ m-2 d-1).  Estimated Rs values reduced the estimation error of PM-ETo and, thus, allows its application for further studies.

How to cite: Vásquez, C., Córdova, M., Carrillo, G., and Célleri, R.: Improving reference evapotranspiration (ETo) calculation under limited data conditions in the Tropical Andes , EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-5670, https://doi.org/10.5194/egusphere-egu2020-5670, 2020.

EGU2020-12884 | Displays | HS2.1.6

Impacts of invasive fauna and wildfires on hydrological regimes in a tropical valley of New Caledonia (SW Pacific)

Caroline Tramier, Pierre Genthon, Quentin Delvienne, Nicolas Sauvan, Jean-Jérôme Cassan, Etienne Ebrard, Pascal Dumas, and Yann Queffelean

In New Caledonia wildfires and invasive animal species (deers and wild pigs) constitute major agents of land surface degradation and an important threat to forests. As a result of land degradation the lagoon and the quality of drinking water are impacted by sediments transported by rivers. The study area, the Thiem watershed, is located on the northeast windward coast of New Caledonia and on micaschist basement. The landscape is constituted by a mosaic of savannahs and forests. Forests are restricted to highest remote areas or near talwegs and waterways. Savannahs are located on the crests and on the superior slopes of watersheds, near the villages. The hydrological regime of contrasted land surfaces is assessed using a 1 year record from three 100 m2 plots located in a healthy forest, in a forest degraded by invasive fauna and in a woody savannah regularly burned. Significant isolated rainy events (50-100 mm rainfall) were observed during the dry season (May-December), while the wet season presented only few isolated dry periods. Difference of monthly rainfall between the three plots were less than 10% as a general rule. However rainfall difference reach 30% at the scale of a rainy event. Moreover, 40% of rain occurs during small events with less than 50 mm cumulated rainfall, although events larger than 200 mm were observed. The healthy forest corresponds to an annual runoff coefficient of 0.04 which is commonly observed in tropical forests. The savannah corresponds to a 0.16 coefficient which is in the high range of those commonly observed in similar tropical areas. The degraded forest presents a 0.86 runoff, rising to more than 100% for many rainy events of the wet season. The maximum event-based runoff coefficient was observed in the three plots during the OMA cyclone, corresponding to 0.18, 0.71 and 2.7 at the healthy forest, savannah and degraded forest respectively. It is proposed that the extra runoff (ER) regularly observed at SCAR results from subsurface flow originating from the upstream area and focused toward the plot. A reservoir model is proposed and calibrated against available data. The model results indicate that ER accounts for 47% of the total observed runoff in this plot. Our study confirms the major role played by subsurface flow in the water regime of forested and savannah areas. It is emphasized that subsurface flow exfiltration in degraded land surfaces could enhance erosion and transport of harmful bacteria (leptospira). Moreover savannah, as a dominant high runoff surface in upper catchments of our study area, might control runoff at the scale of the watershed and might constitute a target for controlling downstream flooding and gullies erosion.

How to cite: Tramier, C., Genthon, P., Delvienne, Q., Sauvan, N., Cassan, J.-J., Ebrard, E., Dumas, P., and Queffelean, Y.: Impacts of invasive fauna and wildfires on hydrological regimes in a tropical valley of New Caledonia (SW Pacific), EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-12884, https://doi.org/10.5194/egusphere-egu2020-12884, 2020.

EGU2020-11971 | Displays | HS2.1.6

Hydrosedimentological monitoring and modeling in paired watersheds in the Pampa biome

Franciele de Bastos, José Miguel Reichert, Éderson Diniz Ebling, and Stephan Hörbinger

In the last years, the intensification of erosive processes from inappropriate land use and management have made sediment production a worldwide problem, compromising soil physical and chemical quality, and water quality and quantity. This source of pollution can be reduced by understanding hydrological processes. Catchment scale monitoring allows the identification of the effects of anthropogenic actions on these processes, enabling assertive decision-making to reduce erosion processes. Modeling tools have been widely used in environmental studies, helping to understand the processes and providing the prediction of future scenarios. However, the development and use of models capable of simulate hydrossedimentological flows in forest areas are still incipient. The goal of this study was to represent the behavior and to understand the dynamics of hydrological and sedimentological processes by monitoring and modeling with the Limburg Soil Erosion Model (LISEM) two small paired rural watersheds. The study was conducted in two paired watersheds, with land use based in eucalyptus plantation (EW, 0.83 km²) and grassland (GW, 1.10 km²), both located in the Pampa biome, in the state of Rio Grande do Sul, Brazil. The hydrosedimentometric monitoring was conducted from January to March 2019, in fluviometric monitoring sections composed of flumes and equipped with level, precipitation, and turbidity sensors to quantify flow, rainfall, and concentration of suspended sediments, respectively. Three events of similar magnitude, with total rainfall accumulation of approximately 30 mm, were simulated for the two catchments studied. The modeling was applied to the scale of individual events. The results were evaluated by surface runoff, peak flow time, and total sediment production, observed and simulated. The percentage trend (PBIAS) was used to evaluate the percentage of overestimation or underestimation of the simulated data in relation to the measured ones. To evaluate the simulated hydrograph shapes and total sediment yield, the Nash and Sutcliffe Efficiency Coefficient (NSE) was used. LISEM satisfactorily represented the runoff in rainfall events of different intensities for both basins, supported by the Nash and Sutcliffe coefficients (> 0.50) and PBIAS or ERROR (< 25% for runoff and < 55% for the production of sediments). The model was unable to represent sediment production satisfactorily (< 0.50). This may be associated with spatial variability of the soil and the characteristics of the model used, which simulates the surface flow promoted by individual rainfall events in watersheds. In the study area, the influence of forest cover associated with sandy soil with deep clay accumulation favors the subsurface erosive process. FW had lower total sediment yield and lower peak flows, which is associated with the vegetation type. With the incidence of rain in the forest compartment, part of it is compartmentalized upon reaching the forest canopy, part seeps through the trunk, reaching the litter at a lower speed, favoring infiltration and decreasing surface runoff. Our studies are in the early stages, continued monitoring is necessary to evaluate events of different magnitudes, and to identify a model capable of adequately representing the predominant subsurface runoff in forest areas.

How to cite: de Bastos, F., Reichert, J. M., Ebling, É. D., and Hörbinger, S.: Hydrosedimentological monitoring and modeling in paired watersheds in the Pampa biome, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-11971, https://doi.org/10.5194/egusphere-egu2020-11971, 2020.

EGU2020-20254 | Displays | HS2.1.6

Assessing spatially distributed hydrological drought hazard in data scarce tropical catchments

Alexandra Nauditt, Hamish Hann, and Marko Kallio

Although water-rich, tropical regions are facing severe drought disasters worldwide, especially during their dry seasons. To design site appropriate adaptation measures, a profound understanding of spatially varying hydrological drought severity and frequency is of crucial importance. However, low flow behaviour can strongly vary in space and time, depending on catchment characteristics, but discharge datasets of high temporal and spatial resolution needed for its assessment are rarely available. Our objective was therefore to provide hydrological drought hazard information to detect hydrological drought anomalies in quickly responding tropical environments.

We used daily discharge time series of an unregulated rural tropical test catchment, the Muriaé in southeast Brazil, to calibrate the semi distributed hydrological model SWAT2012. For the outlets of 93 hydrological response units, we simulated discharges to obtain an adequate spatial distribution. The hydrostreamer 4.0 downscaling approach (https://github.com/mkkallio/hydrostreamer) was applied to the ISIMIP 2a global discharge data product and calibrated with discharge observations and the simulations. Downscaling to a resolution of 450 m was carried out by evaluating the relationship between a spatial unit of discharge and the overlaid river network. To assess hydrological drought hazard, we applied the daily variable Q95 threshold to the dry season flow time series for each grid cell (0.1°). Drought events were defined for periods when the discharge values fell below this dry season threshold during 5 days (and 12 days respectively). To further understand the role of catchment characteristics in low flow evolvement, we tested the sensitivity of different climate and catchment related model input variables against low flow events and simulated artificial drought risk scenarios.

Drought hazard assessment results showed the largest number of drought events in the downstream area, probably attributed to geological and tectonic fracturation and hence increased infiltration, followed by the Western upstream region – that could be linked to  smaller subcatchment sizes and lower precipitation inputs.
Only limited hydrological drought sensitivity of the system against changes in land cover type and temperature was found in the model results, while geology and soils turned out to play a larger role for low flows. The drought scenarios also indicated that low flows were more severely affected than high flows by climatic changes such as decreased precipitation.

Our findings related to the ocurrence of hydrological hazards in the region coincide with institutional records by government institutions (CEMADEM), newspaper reports and stakeholder communication about water shortage in communes and districts.  We conclude that the here presented hydrological drought assessment approach provides science based data sets, indicators and information to be used in regional and local drought management in tropical regions.

How to cite: Nauditt, A., Hann, H., and Kallio, M.: Assessing spatially distributed hydrological drought hazard in data scarce tropical catchments, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-20254, https://doi.org/10.5194/egusphere-egu2020-20254, 2020.

EGU2020-13019 | Displays | HS2.1.6

Changes in atmospheric and hydrological dynamics at the Colombian Amazon in scenarios of forest loss

Monica Bonilla-Rodriguez and Sebastian Gomez-Rios

The Colombian Amazon exhibits complex hydro-meteorological features, as it links the biggest tropical rainforest of the world with the Andes range and the savannahs of the Orinoco basin. Similar to other amazon areas in neighboring countries, this high-biodiversity region faces severe deforestation due the agricultural expansion, illegal logging, and mining. Numerous studies have stated the role of the Amazon over the climatic system, and the complex interactions between the rainforest, the atmospheric dynamics and the hydrological response of the rivers. Furthermore, previous studies have warned about the effects of the loss of vegetal coverage in the Amazon over hydro-meteorological patterns in northern South America.

This work aims to study the effects of deforestation over some atmospheric and hydrological features in the Colombian Amazon. Taking into account present and historical rates of deforestation, there are defined scenarios of moderate and intense forest loss. Changes in precipitation and moisture fluxes over the area are investigated using the atmospheric model WRF (Weather Research and Forecasting). High-resolution simulations are performed for a study period composed of typical rainy and dry months, considering the changes in land use of each scenario. The effects of forest loss over streamflow in some rivers of the region are assessed using the results from the atmospheric model and simulations in an aggregated hydrological model. The main finding suggests that low-level moisture flux over the Colombian Amazon and neighboring Andean foothills decrease with the reduction of the rainforest cover in both of the considered seasons. As a consequence, precipitation decreases over the area, triggering a reduction of the streamflow in the studied rivers.

How to cite: Bonilla-Rodriguez, M. and Gomez-Rios, S.: Changes in atmospheric and hydrological dynamics at the Colombian Amazon in scenarios of forest loss, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-13019, https://doi.org/10.5194/egusphere-egu2020-13019, 2020.

According to United Nations, the world population in 2050 will reach 9.7 billion and it is expected that 68% will live in urban centers. An important part of the urban population in Latin America is concentrated in megacities such as Mexico City and Sao Paulo, which currently have more than 20 million inhabitants. Buenos Aires, Rio de Janeiro, Lima and Bogotá are now megacities under development. This accelerated process of urbanization entails effects on the demand of the natural resources and the impulse of the environmental negative effects related to the contamination of soil, air and water.

The megacity of Bogotá and its metropolitan area includes more than 10 million inhabitants being the higher population density of Colombia. Being the country’s capital city, it is the core of its economic development and it is currently one of the main business centers of South America.

From an environmental perspective Bogotá basin becomes a territory with high water vulnerability. The accelerated population increase (it has doubled during the last four decades), has caused, among others, high water resources demand. The industrial concentration in this territory has also affected both surface and subsurface water quality, causing an increase in the purification costs.

The objective of this study is to analyze the influence in the water cycle of the urban growth of the city of Bogotá in the last forty years. In this period the Bogotá river basin was modeled for the years 1985, 2005 and 2014, using the TETIS distributed hydrological simulation model. Results allow to identify the alterations in the basin water balance induced by changes in land use during the period of analysis.Por favor inserte su resumen HTML aquí.

How to cite: Romero, C. P. and Frances, F.: Impact of the megacity’s growth over the hydrological cycle of the Bogotá basin (Colombia) using distributed model, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-15895, https://doi.org/10.5194/egusphere-egu2020-15895, 2020.

EGU2020-647 | Displays | HS2.1.6

Modeling of a forested study site with the Community Land Model version 5 using climate projections for the 21st century.

Lukas Strebel, Klaus Goergen, Bibi S. Naz, Heye Bogena, Harry Vereecken, and Harrie-Jan Hendricks Franssen

Modeling forest ecosystems is important to facilitate adaptations in forest management approaches necessary to address the challenges of climate change, particularly of interest are ecohydrological states and fluxes such as soil water content, biomass, leaf area index, and evapotranspiration.

The community land model in its current version 5 (CLM5) simulates a broad collection of important land-surface processes; from moisture and energy partitioning, through biogeophysical processes, to surface and subsurface runoff. Additionally, CLM5 contains a biogeochemistry model (CLM5-BGC) which includes prognostic computation of vegetation states and carbon and nitrogen pools. However, CLM5 predictions are affected by uncertainty related to uncertain model forcings and parameters. Here, we use data assimilation methods to improve model performance by assimilating soil water content observations into CLM5 using the parallel data assimilation framework (PDAF).

 

The coupled modeling framework was applied to the small (38.5 ha) forested catchment Wüstebach located in the Eifel National Park near the German-Belgian border. As part of the terrestrial environmental observatories (TERENO) network, the SoilNet sensors at the study site provide soil water content and soil temperature measurements since 2009.

CLM5 simulations for the period 2009-2100 were made, using local atmospheric observations for the period of 2009-2018 and an ensemble of regional climate model projections for 2019-2100. Simulations illustrate that data assimilation of soil water content improves the characterization of past model states, and that estimated model parameters and default model parameters result in different trajectories of ecohydrological states for 2019-2100. The simulations also illustrate that this site is hardly affected by increased water stress in the future.

The developed framework will be extended and applied for both ecosystem reanalysis as well as further simulations using climate projections across forested sites over Europe.

How to cite: Strebel, L., Goergen, K., Naz, B. S., Bogena, H., Vereecken, H., and Hendricks Franssen, H.-J.: Modeling of a forested study site with the Community Land Model version 5 using climate projections for the 21st century. , EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-647, https://doi.org/10.5194/egusphere-egu2020-647, 2020.

EGU2020-6463 | Displays | HS2.1.6

Spatial variation in soil physical properties and effects on soil NO3– production on forest hillslopes

Tomoki Oda, Megumi Kuroiwa, Naoya Fujime, Kazuo Isobe, Naoya Masaoka, Kazumichi Fujii, Hiroto Toda, and Nobuhito Ohte

Ammonium (NH4+) and nitrate (NO3) concentrations and production rates in forest soil vary by hillslope position due to variation in ammonia-oxidizing microorganism concentrations, soil chemistry, and surface soil moisture. These spatial distributions have a significant effect on nutrient cycles and streamwater chemistry. Soil moisture conditions significantly restrict microbial activity, influencing the spatial distribution of NO3 concentrations on forest hillslopes. However, studies linking forest hydrological processes to nitrogen cycling are limited. Therefore, we investigated the determinants of spatial variation in soil moisture and evaluated the effects of soil moisture fluctuations on spatial variation in NO3 concentration and production rate.

The study sites were the Fukuroyamasawa Experimental Watershed (FEW) and Oyasan Experimental Watershed (OEW) in Japan. The two have similar topographies, climates, and tree species. In each watershed, a 100 m transect was set up from the ridge to the base of the slope, and soil moisture sensors were installed at soil depths of 10 cm and 30 cm at both the top and bottom of the slope. We collected surface soil samples at a depth of 10 cm at the top, middle, and bottom of the slopes using 100 cm3 cores, and measured soil physical properties, particle size distribution, volcanic ash content, chemical properties (pH, NO3, NH4+, nitrification rate, and mineralization rate), and microbial content (archaeal content). Spatial and temporal changes in soil moisture on the hillslope were calculated using HYDRUS-2D to examine contributing factors of soil moisture.

At FEW, high NO3 concentrations and nitrification rates were observed only at the slope bottom and middle, and no NO3 concentrations were detected at up slope. By contrast, at OEW, high NO3 concentrations and nitrification rates were observed at all points. NH4+ concentrations were similar at all points in both watersheds. At FEW, 10 cm surface soil moisture fluctuated within 25–40% at the slope top but was within 40–50% at the slope bottom. At OEW, surface soil moisture was 30–40% at both the slope top and bottom, with no significant differences according to slope position. It was confirmed that soil moisture was significantly involved in NO3concentration and nitrification rates. Model simulations showed that the difference in soil moisture fluctuations between FEW and OEW was mainly explained by the spatial variation in soil physical properties. In particular, volcanic ash influenced soil moisture along the entire slope at OEW, resulting in high water retention, but only influenced soil moisture at the slope bottom at FEW. These findings indicate that spatial variability in soil physical properties has a significant effect on soil moisture fluctuation and leads to a spatial distribution of NO3 production.

How to cite: Oda, T., Kuroiwa, M., Fujime, N., Isobe, K., Masaoka, N., Fujii, K., Toda, H., and Ohte, N.: Spatial variation in soil physical properties and effects on soil NO3– production on forest hillslopes, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-6463, https://doi.org/10.5194/egusphere-egu2020-6463, 2020.

EGU2020-8774 | Displays | HS2.1.6

Global analysis of mountain forest distribution and change during 2000 to 2018

Xinyue He, Dominick Spracklen, Joseph Holden, and Zhenzhong Zeng

Mountain forests cover a small fraction of the Earth’s surface, but may exert important influence on the hydrological cycles of river basins (e.g., evapotranspiration, river flow). Many montane ecosystems are currently experiencing forest loss or gain, due to direct land-use change and due to changes in climate. Previous studies revealed most deforestation and afforestation occur in the lowlands, while how forest cover changes at different altitudes in the mountains has not been fully understood. Here we present a study that aims to better understand the distribution of mountain forest change. We use a high-resolution global map of forest change during 2000-2018 combined with elevation data to complete a global analysis of the relationship of elevation with tree cover and tree cover loss and gain. We also assess which climate variables (temperature, rainfall, wind speed) might explain observed variations in tree cover. Our analysis provides new information on how and why mountain forests are changing.

How to cite: He, X., Spracklen, D., Holden, J., and Zeng, Z.: Global analysis of mountain forest distribution and change during 2000 to 2018, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-8774, https://doi.org/10.5194/egusphere-egu2020-8774, 2020.

EGU2020-10136 | Displays | HS2.1.6

The response of Bonis Catchment in Calabria –Southern Italy to different management options under climate change scenarios.

Mouna Feki, Giovanni Ravazzani, Tommaso Caloiero, and Gaetano Pellicone

Forests ecosystems provide several ecosystem services among which the regulation of the hydrological cycle. These ecosystems are exposed to different forms of disturbances induced by human activities, management strategies, and climate change. The objective of INNOMED project, for the Italian case study, is to understand the response of forest to different silvicultural practices under climate change conditions. The study site is the the Bonis catchment located in the mountain area of Sila Greca (39°25’15’’N, 16°12’38’’W), in the Calabria region (southern Italy). This small catchment has a surface of 1.39 km2 and a mean elevation of 1131 m above sea level. Almost 93% of the total area is covered by forest stand, dominated by about 50-year-old Calabrian pine (Pinus laricio Poiret) forests. In order to simulate the response of the catchment to different climate and management scenarios, FEST-WB distributed hydrological model was used. Within the framework of this project, FEST-FOREST module has been implemented in order to consider vegetation dynamics interactions with the hydrological response of the watershed. Since 1986, the basin was monitored through the installation of different instruments. Rainfall was measured by three rain gauges (with a tipping bucket) together with temperature that were measured at three different meteorological stations. In May 2003, a tower for measurement of eddy fluxes was installed at an altitude of 1100 m a.s.l, on a 54 years old plantation of Laricio pine which allowed monitoring of other parameters. Runoff was measured at the outlet of the catchment using a gauging structure. These data were used for the calibration and validation of the model before being implemented for future scenarios simulations. The results of these simulations delivered the potential impacts and the vulnerability of the Bonis catchment to different scenarios. These outcomes provide for the stakeholders a scientifically based and solid information for a sustainable management of the catchment.

How to cite: Feki, M., Ravazzani, G., Caloiero, T., and Pellicone, G.: The response of Bonis Catchment in Calabria –Southern Italy to different management options under climate change scenarios., EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-10136, https://doi.org/10.5194/egusphere-egu2020-10136, 2020.

EGU2020-11234 | Displays | HS2.1.6

How sensitive are rainfall interception models to the canopy parameters of semi-arid forests?

Marinos Eliades, Adriana Bruggeman, Hakan Djuma, and Maciek W. Lubczynski

Quantifying rainfall interception can be a difficult task because the canopy storage has high spatial and temporal variability. The aim of this study is to examine the sensitivity of three commonly used rainfall interception models (Rutter, Gash and Liu) to the canopy storage capacity (S) and to the free throughfall coefficient (p).  The research was carried out in a semi-arid Pinus brutia forest, located in Cyprus. One meteorological station and 15 manual throughfall gauges were used to measure throughfall and to compute rainfall interception for the period between January 2008 and July 2016. Additionally, one automatic and 28 manual throughfall gauges were installed in July 2016. We ran the models for different sets of canopy parameter values and evaluated their performances with the Nash-Sutcliffe Efficiency (NSE) and the bias, for the calibration period (July 2016 - December 2019). We validated the models for the period between January 2008 and July 2016. During the calibration period, the models were tested with different temporal resolutions (hourly and daily). Total rainfall and rainfall interception during the calibration period were 1272 and 264 mm, respectively. The simplified Rutter model with the hourly interval showed a decrease of the NSE with an increase of the free throughfall coefficient. The bias of the model was near zero for a canopy storage between 2 and 2.5 mm and a free throughfall coefficient between 0.4 and 0.7. The Rutter model was less sensitive to changes in the canopy parameters than the other two models. The bias of the daily Gash and Liu models was more sensitive to the free throughfall coefficients than to the canopy storage capacity. The bias of these models was near zero for free throughfall coefficients over 0.7. The daily Gash and Liu models show high NSE values (0.93 – 0.96) for a range of different canopy parameter values (S: 0.5 – 4.0, p: 0 – 0.9). Zero bias was achieved for a canopy storage capacity of 2 mm and above and a free throughfall coefficient between 0 and 0.7. Total rainfall and rainfall interception during the validation period were 3488 and 1039 mm, respectively. The Gash model performed better than the Liu model when the optimal parameter set (highest NSE, zero bias) was used. The interception computed with the Gash model was 987 mm, while 829 mm with the Liu model. This study showed that there is a range of canopy parameter values that can be used to achieve high model performance of rainfall interception models.

How to cite: Eliades, M., Bruggeman, A., Djuma, H., and Lubczynski, M. W.: How sensitive are rainfall interception models to the canopy parameters of semi-arid forests? , EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-11234, https://doi.org/10.5194/egusphere-egu2020-11234, 2020.

EGU2020-13328 | Displays | HS2.1.6

Roles of clay layers in rainfall-runoff processes in a serpentinite headwater catchment

Takahiko Yoshino and Shin'ya Katsura

Rainfall-runoff processes in a headwater catchment have been typically explained by water flow in permeable soil layers (comprised of organic soil layers and mineral soil layers produced by weathering of bedrock) overlying less permeable layers (i.e., bedrock). In a catchment where mineral soils are characterized by clayey materials (e.g., mudstone, slate, and serpentine catchment), it is possible that mineral soil layers function substantially as less permeable layers because of a low permeability of clayey materials. However, roles of clay layers in rainfall-runoff processes in such a headwater catchment are not fully understood. In this study, we conducted detailed hydrological, hydrochemical, and thermal observations in a serpentinite headwater catchment (2.12 ha) in Hokkaido, Northern Japan, where mineral soil layers consisting of thick clay layers (thickness: approximately 1.5 m) produced by weathering of the serpentinite bedrock underlies organic soil layers (thickness: approximately 0.4 m). Saturated hydraulic conductivity (Ks) and water retention curve of these two layers were also measured in a laboratory. The observation results demonstrated that groundwater was formed perennially in the organic soil layers and clay layers. The groundwater level within the organic soil layers and specific discharge of the catchment showed rapid and flashy change in response to rainfall. In contrast, the groundwater level within the clay layers showed slow and small change. Temperature of the groundwater and stream water suggested that water from the depth of the organic soil layers contributed to streamflow. The electric conductivity (EC) of the groundwater in the clay layers was very high, ranging from 321 to 380 µS cmˉ¹. On the other hand, the EC of soil water (unsaturated water stored in the organic soil layers) was relatively low, ranging from 98 to 214 µS cmˉ¹. Hydrograph separation using EC showed that contribution of water emerging from the clay layers to the total streamflow ranged from 31 to 76% in low to high flow periods. Temporal variation in the total head, measured using tensiometers installed at four depths at the ridge of the catchment, indicated that in wet periods when the groundwater level in the organic soil layers was high, water flow from the organic soil layers to the clay layers occurred, whereas, in dry periods, water flow from the clay layers into the organic soil layers occurred. The laboratory measurements showed that the organic soil layers had high Ks (10ˉ² cm sˉ¹) and low water-holding capacity, whereas the clay layers had low Ks (10ˉ⁴ cm sˉ¹) and high water-holding capacity. It can be concluded from these results that clay layers play two roles: (1) forming perched groundwater table and lateral flow on the clay layers (the role of less permeable layers) and (2) supplying water into the organic soil layers in the dry periods (the role of water supplier).

How to cite: Yoshino, T. and Katsura, S.: Roles of clay layers in rainfall-runoff processes in a serpentinite headwater catchment, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-13328, https://doi.org/10.5194/egusphere-egu2020-13328, 2020.

EGU2020-14495 | Displays | HS2.1.6

Stable isotope-based approach to validate effects of stand structure and understory on soil water in a Japanese forest plantation

Saki Omomo, Yuichi Onda, Boutefnouchet Mohamed, Chenwei Chiu, Takashi Gomi, Sean Hudson, Yupan Zhang, and Janice Hudson

 Many researchers have studied the effects of plantation thinning on forest environments, including plantation thinning-induced changes in soil water, which recharges ground water. However, most of these studies have sampled only either preferential flow or matrix flow. To properly understand soil water movement, soil water must be classified into matrix flow and preferential flow, and we must sample and analyze them separately. Therefore, our purpose is to reveal the differences in the water stable isotope rates in soil water on different vegetation distributions to consider the change of soil water.

 We used suction lysimeters adding 60kPa and zero-tension lysimeters to collect two types soil water separately. We used modular zero-tension plate lysimeters which improve the problems in conventional zero-tension plate lysimeter of both low water collection efficiency by unsaturated soil on the plate and soil disturbance by inserting the plate.

 Matrix flow tended to be isotopically heavier under open canopy than under closed canopy, and isotopically heavier in areas with no understory vegetation than in areas with understory vegetation. Preferential flow tended to be almost the same water stable isotope rate as throughfall. We could see this trend better in heavy rain events than in light rain events, and the trend suggests mixing with matrix flow in the light rain. There was little difference between water stable isotope rates of throughfall in different vegetation distributions.

 The implications of these results suggest that soil water which recharges ground water is isotopically heavy in a degraded plantation, and becomes isotopically heavier with the increase in forest floor evaporation after plantation thinning, but becomes isotopically lighter as understory vegetation grows.

How to cite: Omomo, S., Onda, Y., Mohamed, B., Chiu, C., Gomi, T., Hudson, S., Zhang, Y., and Hudson, J.: Stable isotope-based approach to validate effects of stand structure and understory on soil water in a Japanese forest plantation, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-14495, https://doi.org/10.5194/egusphere-egu2020-14495, 2020.

EGU2020-20932 | Displays | HS2.1.6

Sap flow dynamics of xerophytic shrubs differ significantly among rainfall categories in the Loess Plateau of China

Di Wang, Guangyao Gao, Junran Li, Chuan Yuan, Yihe Lü, and Bojie Fu

Global climate change is likely to change the timing, frequency and magnitude of precipitation events, studying the response of sap flow (SF) of plants to rainfall events is thus important for understanding the response of ecosystems to global climate change. Here, we conducted a comprehensive study on the SF, rainfall events, meteorological factors and soil water for two typical xerophytic shrub stands (Caragana korshinskii and Salix psammophila) on the Loess Plateau of China for two rainy seasons (from June-September) in 2015 and 2016. The rainfall events were classified into three rainfall categories using the K-means clustering based on the rainfall amount (RA), rainfall duration (RD) and rainfall intensity (RI) (category I: lowest mean RA, RD and RI, category II: moderate mean RA, RI and highest mean RD and category III: highest mean RA, RI and moderate mean RD). The results showed that the response of SF at both C. korshinskii and S. psammophila stands to rainfall events differed under the three categories. The occurrence of rainfall events significantly decreased daily SF of C. korshinskii in three rainfall categories, whereas the daily SF of S. psammophila is more strongly influenced by rainfall category II. Maximum decreases in daily SF between the pre-rainfall and the rainfall weather condition of the two stands both occurred in rainfall category II. Daily rainfall SF at both stands was strongly correlated with daily SR, RH and VPD, regardless of the rainfall categories. Diurnal variation of hourly SF at both stands also differed among the days with similar RA and RD in the same rainfall category. It can be inferred that SF of C. korshinskii is more susceptible to rainfall events than S. psammophila. Rainfall characteristics (RA, RD and RI) and rainfall distribution should be fully considered when assessing the response of SF of shrubs to rainfall events.

How to cite: Wang, D., Gao, G., Li, J., Yuan, C., Lü, Y., and Fu, B.: Sap flow dynamics of xerophytic shrubs differ significantly among rainfall categories in the Loess Plateau of China, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-20932, https://doi.org/10.5194/egusphere-egu2020-20932, 2020.

EGU2020-20974 | Displays | HS2.1.6 | Highlight

Post-fire changes in streamflow explained by forest self-thinning behavior

Assaf Inbar, Richard Benyon, Raphaël Trouvé, Patrick Lane, Shane Haydon, and Gary Sheridan

Most of the drinking water provided to the Melbourne metropolitan area originates from catchments that are covered by tall-wet eucalyptus forests, which have an estimated mean fire return interval of 80-150 yr. When stand-replacing fires occur in these forests, they result in a significant reduction in streamflow for an extended period of time due to the recovery strategy of the dominant tree species (Eucalyptus regnans and Eucalyptus delegatensis) and the water use of the dense regrowth. Current hydrological models that express this phenomenon are based on empirical data and lack the mechanistic explanation that links changes in streamflow with forest stand dynamics after disturbance. Here, for the first time, we present a simple theoretical framework that shows that this post-fire reduction in streamflow could be explained by the self-thinning behaviour of forest regrowth, which is driven by competition for water and light during recovery after a stand-replacing fire. First, we show that the trend in streamflow following a stand-replacing fire can be replicated simply by using the generic self-thinning line (which represents the maximum carrying capacity of a forest stand for a given mean tree diameter) of the dominant tree species. We then go one step further and show that the magnitude of streamflow reduction and the time it takes for streamflow to recover to pre-fire conditions, are sensitive to both the recovery success and the environmental conditions that control the maximum vegetation carrying capacity across the catchments. By using a simple stand growth and mortality model, we link the competition for water and light and the self-thinning behaviour of the forest to evapotranspiration and streamflow trajectories. This theory provides a simple alternative approach that can be used to improve models that predict streamflow from forested catchments after stand-replacing fires.

How to cite: Inbar, A., Benyon, R., Trouvé, R., Lane, P., Haydon, S., and Sheridan, G.: Post-fire changes in streamflow explained by forest self-thinning behavior, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-20974, https://doi.org/10.5194/egusphere-egu2020-20974, 2020.

EGU2020-21679 | Displays | HS2.1.6

Is phosphorus export from beech forest stands transport-limited of source-limited?

Michael Rinderer and Markus Weiler

Phosphorus (P) is one of the key limiting nutrients in forest ecosystem resulting in tight P-recycling strategies in natural forests. Hydrological fluxes in the subsurface during rainfall events can however lead to a relocation and export of P from the forest stands. We present results from six large-scale sprinkling experiments on three highly instrumented experimental hillslope in the Bavarian Forest, Black Forest, and the Swabian Alb in Germany that differ in their soil P stocks. We simulated an extreme 150 mm rainstorm with intensities between 12 and 15 mm/h. The aim of these experiments was to quantify the lateral and vertical fluxes of subsurface storm flow and phosphorus under a range of input fluxes and to identify differences in the degree of nutrient retention depending on the prevailing soil properties of the three forest sites.

We sprinkled the 200 m2, steep hillslopes with 60,000 l of isotopically (deuterium) labeled water for 11 h. Lateral subsurface flow was measured at three depths (10cm, 240cm, 300cm) at a 10 m wide trench at the bottom of the hillslope and with large zero-tension lysimeters (area of 0.6 m2) installed at four depths into the undisturbed soil profile. This setup allowed us to quantify the lateral and vertical fluxes of subsurface flow and phosphorus concentration during the experiment in 30 min temporal resolution. We found vertical subsurface flow to dominate over lateral flow by more than one order of magnitude. We could identify a P-flashing (i.e., high P concentrations) in the first 2 hours after start of subsurface flow across all soil depths. During the rest of the sprinkling the P-concentrations were lower but did not change significantly despite further increasing subsurface flow. We explored P concentrations as a function of subsurface flow and found for all observations, except those from the litter layer, to be chemostatic. We also found no change in P-concentrations with increasing new water fraction, calculated based on a two-component hydrograph separation approach using the deuterium label as tracer. However, when calculating the internal and total P-fluxes we realized that the majority of P, that was leached from the litter layer (i.e., 0.22 kg/ha at the P-poor site and 1.17 kg/ha at the P-rich site), was retained in the mineral soil. The total vertical and lateral losses from the experimental hillslope were small (i.e., 0.07 kg/ha at the P-poor site and 0.06 kg/ha at the P-rich site during each experiment).

Therefore, our results suggest that P-poor and P-rich forest ecosystems are efficiently retaining phosphors in their mineral soils. However, as phosphorus export is transport limited but not source limited an increase in the frequency of heavy rainstorms, as predicted under future climate conditions, might still lead to a relocation of phosphorus to soil depths below the depth of tree roots or even cause increased P-export from the forest stands.

How to cite: Rinderer, M. and Weiler, M.: Is phosphorus export from beech forest stands transport-limited of source-limited?, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-21679, https://doi.org/10.5194/egusphere-egu2020-21679, 2020.

EGU2020-22353 | Displays | HS2.1.6

Influence of beech and spruce forests on soil water dynamics

Vaclav Sipek, Jan Hnilica, Lukáš Vlček, Soňa Hnilicová, and Miroslav Tesař

This study focuses on the description of soil water dynamics at four sites with different land cover types, namely beech forest, conifer forest, meadow and clipped grass. The analysis was based on soil tensiometer measurements from five consecutive vegetation seasons (comprising both wet and dry years). We investigated both column average pressure heads and also their vertical distribution. The soil water balance was studied by the HYDRUS-1D model. The highest pressure heads were observed at the grassland site, followed by the meadow site. The forested sites were generally reaching lower pressure head values, which was a result of higher evapotranspiration and different soil properties. The differences between the spruce forest (Picea abies (L.)) and beech forest (Fagus sylvatica L.) were evident namely in dry periods, when the beech site was experiencing lower pressure heads. Contrarily, the spruce site was drier (with recorded lower pressure heads) in wet periods and at the beginning of each season. Compared to the conifer forest, lower pressure heads were observed in beech forest, namely at the bottom of the inspected soil column (down to 100 cm). The inspection of the soil water balance revealed different rates of evapotranspiration and drainage at all sites. The evapotranspiration was highest in the beech canopy followed by spruce and both grass covered sites. The differences between spruce and beech forest were based namely on the water consumption efficiency and differences in interception rates, vertical distribution of the roots, and soil hydraulic properties.

 

This research was supported by the Czech Science Foundation (GA CR 20-00788S), SoilWater project (EIG CONCERT-Japan), and by the institutional support of the Czech Academy of Sciences, Czech Republic (RVO: 67985874).

How to cite: Sipek, V., Hnilica, J., Vlček, L., Hnilicová, S., and Tesař, M.: Influence of beech and spruce forests on soil water dynamics, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-22353, https://doi.org/10.5194/egusphere-egu2020-22353, 2020.

HS2.1.7 – Hydrological Processes in Agricultural Lands under Changing Environment

EGU2020-1067 | Displays | HS2.1.7

Estimation of Wheat Yield using Remotely Sensed and Modeled Data over Turkey

Burak Bulut, M. Tugrul Yilmaz, and Mehdi H. Afshar

Monitoring agricultural crop conditions during the growing season and estimating potential crop yields are important for evaluating seasonal production. The accurate and timely assessment of the losses in crop yields caused by a natural disaster, such as drought, may be critical for countries where their economies are reliant on their agricultural productivity. Early assessment of the reduction in crop yields can prevent a catastrophic situation and help meet the demands of strategic planning.

In this study, the Multiple Linear Regression model was used to estimate the wheat yields in Turkey. Remotely sensed-, model-, and in-situ-based measurements of affecting variables of crop productivity (i.e., precipitation, land surface temperature, soil moisture, wind, and Normalized Vegetation Difference Index) were extracted over selected areas in which yield data were available on them. The datasets are collected using different time scales (e.g., before/during sowing period, growing season, one/two months before harvest, etc.).

The cross-validation of more than 700 different model combinations over more than total 700 different administrative divisions (i.e., districts, provinces, and regions) showed that by using the best model selected for each district, on average, a correlation value of 0.65 and a mean absolute error of 35 kg/da can be obtained between estimated and observed yield values. While, this consistency is more pronounced over the districts located in the Central Anatolia region where the average production of the wheat in them is more than the rest of districts in the country. Overall, regional differences of the selected predictors of observed yield data, suggest that the land surface temperature can provide a useful exploratory and predictive tool for wheat yield estimation across the country.

How to cite: Bulut, B., Yilmaz, M. T., and H. Afshar, M.: Estimation of Wheat Yield using Remotely Sensed and Modeled Data over Turkey, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-1067, https://doi.org/10.5194/egusphere-egu2020-1067, 2020.

The increase in atmosphere carbon dioxide (CO2) concentrations has been the most important environmental change experienced by agricultural systems. It is still uncertain whether grain yield of the global food crop of maize will remain unchanged under a future elevated CO2 (eCO2) environment. A water transformation dynamic processes experimental device (WTDPED) was developed using a chamber coupled with two weighing lysimeters and a groundwater supply system to explore the water-related yield responses of maize to eCO2. Two experiments were conducted via the WTDPED under eCO2 (700 ppm) and current CO2 (400 ppm) concentrations. Seasonal changes in multiple ecophysiological indicators and related hydrological processes were compared between these two experiments. The results showed that the leaf nitrogen (N) content, chlorophyll content, net photosynthesis rate, and transpiration rate (Tr) consistently decreased during the seedling to filling stages but notably increased at the maturity stage due to eCO2 (P<0.05). Nevertheless, the effects were not significant over the entire growing season or for other indicators, i.e., the leaf carbon (C) content, C/N ratio, and leaf area index (P>0.05). Significant decreases in crop height (mean of 15.9%, P<0.05) associated with notable increases in stem diameter (mean of 14.9%, P<0.05) were found throughout the growing season. Dry matter per corncob at the final harvest decreased slightly under eCO2 (mean of 7.7 g, P >0.05). Soil moisture was not conserved by the decline of Tr ahead of the filling stage when soil evaporation was likely promoted by eCO2 instead. The total evapotranspiration changed little (0.2%) over the entire growing season. Although the leaf water use efficiency increased significantly at every growth stage (mean of 27.3%, P<0.05), the grain yield, water productivity and irrigation water use efficiency were not improved noticeably by eCO2. This study is critical to accurately predict future crop yield and hydrological changes under climate change.

How to cite: Ma, Y.: Seasonal responses of maize growth and water use to elevated CO2 based on WTDPED experiments: evidences from multiple ecophysiological indicators, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-2263, https://doi.org/10.5194/egusphere-egu2020-2263, 2020.

This study develops a recursive approach to long-term prediction of monthly precipitation using genetic programming (GP), and the study area is the Three-River Headwaters Region (TRHR) in China. The daily precipitation data recorded at 29 meteorological stations during 1961-2014 are collected, among which the data during 1961-2000 are used for calibration and the remaining data are for validation. To develop this approach, first, the preliminary estimations of annual precipitation are computed based on a statistical method. Second, the percentage of the monthly precipitation for each month of a year is calculated as the mean monthly precipitation divided by the mean annual precipitation during the study period, and then the preliminary estimation of monthly precipitation for each month of a year is obtained. Third, GP is adopted to improve the preliminary estimations through establishing the relationship of the observations with the preliminary estimations at the past and current times. The calibration and validation results reveal that the recursive approach involving GP can provide the more accurate predictions of monthly precipitation. Finally, this approach is used to predict the monthly precipitation over the TRHR till 2050.

How to cite: Shi, H. and Liu, S.: A recursive approach to long-term prediction of monthly precipitation using genetic programming: case of the Three-River Headwaters Region, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-6268, https://doi.org/10.5194/egusphere-egu2020-6268, 2020.

EGU2020-8144 | Displays | HS2.1.7

Effects of temperature and water stress on agricultural productivity in a semi-arid irrigation system under changing climate

Rike Becker, Stephan Schulz, Ralf Merz, Tim aus der Beek, and Christoph Schüth

The study focuses on the assessment of climate change impacts on the water balance and agricultural productivity in a semi-arid, meso-scale irrigation system, in Punjab, Pakistan.

To simulate potential future water balance changes in our intensively irrigated agricultural study area, we chose the widely used Soil & Water Assessment Tool (SWAT) model software. Using the SWAT model, we were able to incorporate detailed irrigation management strategies into the analysis, and to account for spatially distributed plant physiognomic dynamics and their effects on the local water balance.

Climate change data is taken from the Coordinated Regional Climate Downscaling Experiment (CORDEX; www.cordex.org), which provides a suite of regional climate projections based on Global Climate Models of the Coupled Model Intercomparison Project, Phase 5 (CMIP5). We take into account medium (RCP 4.5) and high (RCP 8.5) greenhouse gas emission scenarios from the IPCC - Fifth Assessment Record (AR5) and study their short (until 2030) and medium term (until 2050) impacts.

The assessment shows the following interesting results regarding climate change impacts on future agricultural productivity in our study area:

  • Temperature stress on plant growth will increase significantly
  • A substantial reduction in future summer crop yields can be expected
  • Temperature stress induces the reduction of biomass production, which causes a decrease in transpiration and hence a decrease in actual evapotranspiration
  • Reduced transpiration counteracts the temperature-induced increase in potential evapotranspiration, which leads to surprisingly low increases in future irrigation water demand despite the significant warming
  • Temperature stress related adaption strategies (e.g. more heat tolerant crops) are under these circumstances more important than increasing irrigation efficiency
  • Even though overall changes in water demand are surprisingly low, higher pressures on surface water and groundwater resources can be expected due to changes in plant growing cycles: Future temperature patterns are expected to speed up the plant growing cycle and increase irrigation demands during the early growing stages. In our study area, this alters the share of irrigation water supply sources (i.e. rain, surface water and groundwater) and leads to higher demands of surface water and particularly groundwater resources, while rainfall contributions decrease.

The study discusses the above mentioned climate change impacts and their interaction. It focuses on the importance of temperature vs. water stress, and elaborates on their implications for potential climate adaption strategies.

How to cite: Becker, R., Schulz, S., Merz, R., aus der Beek, T., and Schüth, C.: Effects of temperature and water stress on agricultural productivity in a semi-arid irrigation system under changing climate, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-8144, https://doi.org/10.5194/egusphere-egu2020-8144, 2020.

EGU2020-11637 | Displays | HS2.1.7 | Highlight

The effects of flooding and drought on water quantity and quality in agricultural drainage systems and streams in Latvia

Ainis Lagzdins, Linda Grinberga, Arturs Veinbergs, Ritvars Sudars, and Kaspars Abramenko

This study was conducted based on systematic and regular water quality and quantity monitoring activities carried out as a part of the Agricultural Runoff monitoring programme in Latvia. This programme was initiated in 1995 and since then aims to document and evaluate the current status and long-term trends in nutrient concentrations and losses at different spatial and temporal scales as affected by meteorological, hydrological, and farming conditions.

Water sampling and flow measurements were carried out at several spatial scales where subsurface and open drainage systems have been installed including 16 experimental plots, 3 subsurface drainage fields, 3 small agricultural catchments, 24 small and medium size rivers. In addition, 21 groundwater monitoring well was established at 6 locations to investigate the effects of agricultural activities on groundwater quality. Water samples were collected on a monthly basis and analyzed for nitrate-nitrogen, ammonium-nitrogen, total nitrogen, orthophosphate-phosphorus, total phosphorus. Continuous flow measurements were made at experimental plots, subsurface drainage fields and small agricultural catchments using hydraulic measurement structures, pressure sensors and data loggers.

The long-term monitoring data (1995 – 2019) showed that water quantity and quality in subsurface and open drainage systems were strongly affect by meteorological conditions at the research site mainly in terms of annual and seasonal patterns of precipitation. Moreover, the flooding conditions in 2017 and drought conditions in 2018 and 2019 indicated that the agronomic activities at the research sites such as crops, tillage operations, types and application rates of fertilizers have a minor role on water quality leaving the agricultural fields. Intensive precipitation outside the growing season in 2017 resulted in the highest nutrient losses, while drought conditions in 2018 resulted in the lowest nutrient losses since this monitoring programme was established. One year of flooding and two consecutive years of drought have emphasized that more specific water and nutrient retention measures are needed in agricultural areas to secure timely removal of excess water from fields and water storage for later use. The analysis of nitrate-nitrogen concentrations obtained at different scales of measurements showed that nutrient concentrations, especially nitrate-nitrogen, decrease if the scale of measurements increases with the highest concentrations at the experimental plot scale followed by subsurface drainage fields, small catchments, and rivers.

How to cite: Lagzdins, A., Grinberga, L., Veinbergs, A., Sudars, R., and Abramenko, K.: The effects of flooding and drought on water quantity and quality in agricultural drainage systems and streams in Latvia, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-11637, https://doi.org/10.5194/egusphere-egu2020-11637, 2020.

Global population is projected to keep increasing rapidly in the next 3 decades, particularly in dryland regions of the developing world, making it a global imperative to enhance crop production. However, improving current crop production in these regions is hampered by yield gaps due to poor soils, lack of irrigation and other management practices. Here we develop a crop modelling capability to help understand gaps, and apply to dryland regions where data for parametrizing and testing models is generally lacking. We present a data assimilation framework to improve simulation capability by assimilating in-situ soil moisture and vegetation data into the FAO AquaCrop model. AquaCrop is a water-driven model that simulates canopy growth, biomass and crop yield as a function of water productivity. The key strength of AquaCrop lies in the low requirement for input data thanks to its simple structure. A global sensitivity analysis is first performed using the Morris screening method and the variance-based Extended Fourier Amplitude Sensitivity Test (EFAST) method to identify the key influential parameters on the model outputs. We begin with state-only updates by assimilating different combinations of soil moisture and vegetation data (vegetation indices, biomass, etc.), and different filtering/smoothing assimilation strategies are tested. Based on the state-only assimilation results, we further evaluate the utility of joint state-parameter (augmented-states) assimilation in improving the model performance. The framework will eventually be extended to assimilate remote sensing estimates of soil moisture and vegetation data to overcome the lack of in-situ data more generally in dryland regions.

How to cite: Lu, Y. and Sheffield, J.: Improving Dryland Crop Simulation by Assimilating Soil Moisture and Vegetation Data, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-13406, https://doi.org/10.5194/egusphere-egu2020-13406, 2020.

EGU2020-16229 | Displays | HS2.1.7 | Highlight

Effects of prospective climate change on pasture productivity in the Italian Alps.

Francesca Casale and Daniele Bocchiola

We present here preliminary results in fulfilment of the project IPCC MOUPA (Interdisciplinary Project for assessing current and expected Climate Change impacts on MOUntain PAstures) project, funded by Fondazione Cariplo of Italy, aimed to i) evaluate potentially modified productivity of pasture lands under climate change scenarios, and subsequent on socio-economic, wildlife and biodiversity impacts, within the Italian Alps, and ii) propose management strategies for pasture and multi-functional use of mountain areas.

In high mountain areas pastures are a source of living for local communities, and further agriculture and livestock supply ecosystems services (ES). In the last century, increase of temperature nearby +1.5°C was observed in the Alpine region, to increase hereon, and future climate scenarios display potential reduction of water availability, with an increase in precipitation extremes, potentially impacting soil moisture, vegetation, and pasture dynamics (phenology/timing), deeply dependent upon precipitation, temperature, and snow cover.

We here defined some fragility indices (FIs), to sketch the effects of climate change on pastures in the Alps, with special focus on Valtellina valley, in the central Alps of Italy. FIs can be used to highlight pressures experienced by pastures, and thresholds for failure, and to develop policies to i) determine zones needing particular management, and adaptation, ii) monitor trends of global environmental stability, iii) evaluate the overall impact of climate change and anthropic influence, and iv) investigate the dynamics of pasture fragility. We chose indices of climate, productivity, and water usage. Some of these FIs can be evaluated starting from observations, but others have to be calculated using models of pasture growth, and water availability. For this reason, a pasture model Poli-Pasture has been set up to simulate the pasture growth, and to evaluate FIs in the target area.

To explore the broad range of variability under uncertain future climate, FIs are calculated for present conditions of pastures, and for future projected conditions using i) three climatic scenarios of AR5 of IPCC (RCP 2.6, RCP 4.5 and RCP 8.5) as depicted by three Global Circulation Models GCMs (EC-Earth, Echam6.0, CCSM4), and ii) four climatic scenarios of the AR6 (RCP 2.6, RCP 4.5, RCP 7.0, RCP 8.5) depicted by three GCMs (EC-Earth3, Echam6.3, CESM2), and some preliminary conclusion are reported for future pasture dynamics, and management therein.

How to cite: Casale, F. and Bocchiola, D.: Effects of prospective climate change on pasture productivity in the Italian Alps., EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-16229, https://doi.org/10.5194/egusphere-egu2020-16229, 2020.

EGU2020-172 | Displays | HS2.1.7 | Highlight

Variability assessment of Irrigation Requirement for Winter Wheat Cropping Under Changing Climate.

Kaushika Gujjanadu Suryaprakash and Hari Prasad Kotnur Suryanarayana Rao

India is primarily an agronomic country and most of the cropping in the Rabi season depends on the rainwater availability. With the ill effects of climate change cropping up, the agriculture sector is expected to take a major hit. This study takes a technical approach on the impact of climate change on the irrigation requirement of wheat cropping by studying the future irrigation requirement based on the temperature and rainfall that can be expected to occur in the future timelines. A root water uptake model involving the solution of the non-linear Richards equation to assess the root-zone moisture movement is formulated and validated. The inputs of the model include the crop data, which, in this case is obtained by field experimentation at the irrigation field laboratory at IIT Roorkee and weather data, which is obtained from the CANESM2 General circulation model for the historical and projected timescales. The historical GCM data for thirty years is bias corrected using the observed data from the India Meteorological department (IMD). The validated root water uptake model is applied to the historical and projected data for a 60 year span for two emission scenarios for RCP 4.5 and 8.5. The output was obtained as soil moisture profiles and frequencies of irrigation required. It was seen that for both the mild and high emission scenarios, the number of irrigation events per cropping period increased. This increase is assessed using variability analysis and for its impacts on the water resources management systems. The variability assessment showed the variation of the irrigation water requirement on annual and decadal scales. This is useful in understanding the historical and expected crop water requirement in view of the climate change effects.

How to cite: Gujjanadu Suryaprakash, K. and Kotnur Suryanarayana Rao, H. P.: Variability assessment of Irrigation Requirement for Winter Wheat Cropping Under Changing Climate., EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-172, https://doi.org/10.5194/egusphere-egu2020-172, 2020.

Groundwater and Sutlej river water are major sources of irrigation in Rupnagar district of Punjab. Water quality was examined for their agricultural suitability using a total of 54 surface water (16 from Sutlej and 6 from Sirsa River) and groundwater (total 32 of ~160 m depth) samples from Pre- (June 2019) and post-monsoon (Dec 2018) seasons. On-site parameters (electrical conductivity, pH, total dissolved solids) indicate permissible pH (pH 6.6-8.2) and conductivity (147-1953 μS/cm), while 18.5% of samples are brackish salt to salt category type on salinity index. The results of these parameters were further interpreted and measured with different irrigation indexes like sodium percent (SP), sodium adsorption ratio (SAR), residual sodium carbonate (RSC), chloride concentrations and Wilcox diagram. Similarly, most of the samples (except Sutlej river water samples) were found to be above permissible limits with respect to SP (5.36-81.01) and RSC (0-6.23), but SAR is indicative of suitability for irrigation purposes (0.11-8.3). The suitability for irrigation as per SAR is because of low sodium content in all the samples relative to calcium and magnesium. The Wilcox diagram of pre-monsoon samples indicate high, medium and low saline to low sodium hazard except 1 sample with high saline to medium sodium hazard and salinity-sodium hazard in post-monsoon is comparatively lower than that of pre-monsoon. However careful observation of the complete data analysis suggests that all the parameters in Sutlej river water samples were found to be suitable for irrigation while most of the groundwater samples and 3 samples from Sirsa river were unfit for irrigation purposes as inferred from SP, RSC and Wilcox diagram.

How to cite: Kaur, N. and Paikaray, S.: Assessment of groundwater and surface water quality for irrigation suitability in Rupnagar District, Punjab, India, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-1060, https://doi.org/10.5194/egusphere-egu2020-1060, 2020.

Crop production in North China largely depends on irrigation, which is mainly from groundwater in Northwest China. Groundwater abstractions are decreasing the groundwater levels, and threatening the fragile ecological systems of arid regions. Here, we examine the dynamic relations between groundwater level and irrigation water for the last three decades in Heihe River basin in China. The average groundwater decline level, attributed to the irrigation water consumption for the farmland area over the past three decades, was calculated. Moreover, the future possible changes are estimated with different RCP senarios. Effective water-saving measures and strategies are expected to adopt to maintain both groundwater levels and agricultural productivity for the coming decades.

How to cite: Niu, J. and Kang, S.: Environmental burdens of groundwater extraction for irrigation over an agricultural land in Northwest China, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-3786, https://doi.org/10.5194/egusphere-egu2020-3786, 2020.

EGU2020-4877 | Displays | HS2.1.7

A unified typology for small European rivers

Jonathan Jupke and Ralf Schäfer

A large number of chemicals such as pharmaceuticals, pesticides and industrial chemicals are in daily use. In Europe alone, an estimated 100,000 chemicals are in current use, of which 30,000 are produced in quantities larger than one ton per year. Chemicals can enter freshwater ecosystems as an intended (e.g. deliberate emission as in the case of pesticides) or unintended (e.g. wastewater discharge as in the case of pharmaceuticals) byproduct of their use. In the environment, many chemicals (hereafter called toxicants) can exert adverse toxic effects on freshwater organisms and in turn on ecosystem functions. The potential toxic effects of chemicals are often examined within the context of Ecological Risk Assessment (ERA). ERA consists of standardized procedures and methods to evaluate the environmental risks of ecological systems. An open question is to what extent ERA needs to account for differences between recipient ecosystems that are subject to chemical exposure. For example, in the European context, is a single ecological threshold concentration per substance sufficient or is the sensitivity of the organism’s dependent on water body size, geology or climate.

As previous studies have shown that the latter factors influence the community composition of algae and invertebrates, we aim to compare the sensitivity of communities across macroecological gradients. 

We established a typology of small streams for eight European countries that captures the major macroecological gradients and identified typical ecological assemblages for each type. The typology is based on the Catchment & Characteristics Modelling 2 database and incorporates catchment properties such as climate, geology, and altitude as well as river attributes such as sinuosity and flow regime statistics. The latter are derived from modeled daily discharge values. Through CLARA-clustering of the resulting data, we obtained a classification into 14 stream classes. We focused on smaller rivers as they constitute the majority of river length, host a higher share of biodiversity than large rivers, and are more susceptible to pollution. The presented typology is built from the ground up with openly accessible data. All code will be made publicly available; thus, it will be easy to update, modify, and extend the typology. Beyond our application the typology can be used to regionalize ecological and hydrological models, to inventory the number and state of different river types or to develop individualized conservation programs.

Based on the identified typical assemblages we can also present preliminary relative sensitivities of stream types towards different toxicants.

How to cite: Jupke, J. and Schäfer, R.: A unified typology for small European rivers , EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-4877, https://doi.org/10.5194/egusphere-egu2020-4877, 2020.

About half of the Danish agricultural land is artificially drained to make land arable and increase crop yield. Those artificial drains, mostly in the form on tile drains, have a significant effect on the groundwater flow patterns and the whole water cycle. Consequently, the drainage system must also be represented in hydrological models that are used to understand and simulate, for example, recharge patterns, groundwater flow paths, or the transport and retention of nutrients. However, representation of drain in regional- and large-scale hydrological models is challenging due to i) issues with scale, ii) a lack of data on the distribution of the drain network, and iii) a lack of direct observations of drain flow. This calls for more indirect methods to inform such models.

We assume that drain flow leaves a signal in certain hydrograph signatures, as it impacts the generation of streamflow. Based on a dataset of observed discharge covering all of Denmark, and simulation results from regional-scale hydrological models, we use machine learning regressors to shed light on possible correlations between hydrograph signatures and artificial drainage. Building up on this step, we run a series of calibration exercises on a hydrological model of the agriculturally dominated Norsminde catchment, Denmark (~100 km2). The model is set up in the DHI MIKE SHE software, as distributed coupled groundwater-surface water models with a grid size of 100 m. The different calibration exercises differed in the objective functions used: either we only use conventional stream flow metrics (KGE), or also include hydrograph signatures that showed sensitive towards drain flow in our regression analysis. We then evaluate the results from the different calibration exercises, in terms of how well the model reproduces directly observed drain flow, and spatial drainage patterns.

Despite including hydrologic signatures in the calibration process, the representation of drain flow in large-scale models remains challenging. Eventually, the insight gained from this and similar studies will be incorporated in the National Water Resources Model for Denmark, to help improving national targeted regulation of nitrate application through fertilizers.

How to cite: Stisen, S., Schneider, R., and Lajer Højberg, A.: Including hydrologic signatures in the calibration of a groundwater-surface water model to improve representation of artificial drain, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-9283, https://doi.org/10.5194/egusphere-egu2020-9283, 2020.

EGU2020-9933 | Displays | HS2.1.7

Modelling the impacts of cranberry farms on the hydrologic regimes of the Bécancour River watershed in Québec, Canada

Silvio J. Gumiere, Paul Celicourt, Jonathan Lafond, and Alain Rousseau

The Bécancour River watershed, located half way between Montréal and Québec City in the Province of Québec (Canada) and covering a surface area of about 2600 km2, is dominated by forest in the upstream portion and agriculture in the downstream portion. The production of cranberries (Vaccinium macrocarpon) is an important feature of this watershed. This crop not only relies on abundant water resources for frost protection, soil moisture management, and harvest and winter flooding, but also on tiled drainage system which together impact the watershed hydrology and flow patterns.

This study aims at modelling the impacts of cranberry farms on the hydrologic regimes of the Bécancour River watershed in Québec, Canada. We dispose of groundwater level and soil tension data at the root zone from two distinct cranberry farms, meteorological data, Ground-penetrating radar (GPR) and stratigraphy data, and LIDAR data collected over a period of 5 years starting in 2014. We setup the hydrological model using the well-known finite-element-based model named FEFLOW to simulate the hydrological behavior of two cranberry farms in the watershed. The preliminary results are promising and demonstrate the potential of the model in a) depicting and understanding hydrological changes in the watershed and b) supporting decision-making regarding water resources management for agricultural production in the region.

How to cite: Gumiere, S. J., Celicourt, P., Lafond, J., and Rousseau, A.: Modelling the impacts of cranberry farms on the hydrologic regimes of the Bécancour River watershed in Québec, Canada, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-9933, https://doi.org/10.5194/egusphere-egu2020-9933, 2020.

EGU2020-11926 | Displays | HS2.1.7

Estimation of Stomatal Conductance using Crop Water Stress Index based on the Thermal Image at a Leaf Scale

Hoejeong Jeong, Jae-Hyun Ryu, Sang-il Na, and Jaeil Cho

  In 1980s, Crop Water Stress Index (CWSI) is suggested to indicate the water stress of crops. CWSI is based on the leaf energy balance, which is closely related to leaf temperature. To calculate CWSI, meteorological factors such as air temperature and vapor pressure deficit should be measured besides leaf temperature. As recent technology has been developed, leaf temperature can be easily observed by thermal camera or infrared thermometer. Stomatal conductance (gs, mmol m-2 s-1) is one of the critical factors to understand crop photosynthesis and water demand. In addition, the behaviors of gs can represent the biotic and abiotic plant stresses. In abnormal condition, such as drought, insects or disease, gs getting lower. The observation of gs will make better to evaluate and predict crop growth and conditions. Therefore, the time series data of gs is useful for the monitoring of crop growth and the quick detection of abnormal crop condition in smart-farming system but there are some limitations to measure gs continuously and easily.

  We assume that there is some relationship between CWSI and gs because both has strong relation to leaf temperature. Thus, the aim of this study is to investigate possibility of estimation of gs using CWSI which is derived from thermal image. Through the data collected from literatures, negative correlations between CWSI and gs were revealed. The slope of correlation was changed according to crop types. In addition, as a result of simulation, there is almost linear negative relationship between CWSI and gs, and the slope was determined by maximum stomatal conductance (gs_max). Field measurement in this study was also demonstrated to identify such correlation. Further, various methods to measure CWSI were tested. This relationship will contribute to not only monitoring of crop stress for irrigation scheduling in smart farm system but also estimating evapotranspiration, photosynthesis, and crop yield.

How to cite: Jeong, H., Ryu, J.-H., Na, S., and Cho, J.: Estimation of Stomatal Conductance using Crop Water Stress Index based on the Thermal Image at a Leaf Scale, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-11926, https://doi.org/10.5194/egusphere-egu2020-11926, 2020.

Spatiotemporal Variability of Potential Evaporation in Heihe River Basin Influenced by Irrigation

Congying Han1,2, Baozhong Zhang1,2, Songjun Han1,2

1 State Key Laboratory of Simulation and Regulation of Water Cycle in River Basin, China Institute of Water Resources and Hydropower Research, Beijing 100038, China.

2 National Center of Efficient Irrigation Engineering and Technology Research-Beijing, Beijing 100048, China.

Corresponding author: Baozhong Zhang (zhangbaozhong333@163.com)

Abstract: Potential evaporation is a key factor in crop water requirement estimation and agricultural water resource planning. The spatial pattern and temporal changes of potential evaporation calculated by Penman equation (EPen) (1970-2017) in Heihe River Basin (HRB), Northwest China were evaluated by using data from 10 meteorological stations, with a serious consideration of the influences of irrigation development. Results indicated that the spatial pattern of annual EPen in HRB was significantly different, among which the EPen of agricultural sites (average between 1154 mm and 1333 mm) was significantly higher than that of natural sites (average between 794 mm and 899 mm). Besides, the coefficient of spatial variation of the aerodynamic term (Eaero) was 0.4, while that of the radiation term (Erad) was 0.09. The agricultural irrigation water withdrawal increased annually before 2000, but decreased significantly after 2000 which was influenced by the agricultural development and the water policy. Coincidentally, the annual variation of Epen in agricultural sites decreased at -40 mm/decade in 1970-2000 but increased at 60 mm/decade in 2001-2017, while that in natural sites with little influence of irrigation, only decreased at -0.5mm/decade in 1970-2000 but increased at 11 mm/decade in 2001-2017. So it was obvious that irrigation influenced Epen significantly and the change of Epen was mainly caused by the aerodynamic term. The analysis of the main meteorological factors that affect Epen showed that wind speed had the greatest impact on Epen of agricultural sites, followed by relative humidity and average temperature, while the meteorological factors that had the greatest impact on Epen of natural sites were maximum temperature, followed by wind speed and relative humidity.

How to cite: Han, C.: Spatiotemporal Variability of Potential Evaporation in Heihe River Basin Influenced by Irrigation , EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-12520, https://doi.org/10.5194/egusphere-egu2020-12520, 2020.

Diffuse nitrogen pollution is a major cause of degraded water quality in rivers and groundwater across Europe. In artificially drained agricultural catchments, nitrate leaching from the root zone is either transmitted directly to streams by tile drains or transported to the groundwater system. Thus, the partitioning of the water flux to drains, the drainage fraction, is an indicator of surface-water/groundwater vulnerability to nitrogen application. This information can be used to target mitigation measures like drain filter technologies and cover crops. Hydrological models are usually employed to assist water management. Yet, for many decision-making applications numerical models are computationally too time-consuming. Additionally, as models are simplifications of the complex natural system, model results are inherently imprecise for grid-scale, and thus field-scale, predictions. To overcome these barriers, we develop metamodels to make predictions of drainage fraction. We train random forest and gradient boosted regression trees statistical metamodels to MIKE SHE-derived 16-year averages of drainage fraction in a regional groundwater model (100x100m) in Denmark. We explore the effects of mappable and non-mappable predictor variables on model performance. The metamodels are used to identify the most important predictor variables for drainage fraction prediction. Based on this, we investigate how grid cells of similar characteristics can be clustered in homogeneous subsets, in which the drainage fraction variability can be used as an uncertainty estimate. The findings could potentially support decision making on spatially differentiated regulation of nitrate emissions.

How to cite: Bjerre, E. and Lajer Højberg, A.: Metamodeling for predicting drainage fraction in groundwater: Development of a decision-support tool, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-14008, https://doi.org/10.5194/egusphere-egu2020-14008, 2020.

EGU2020-14894 | Displays | HS2.1.7 | Highlight

Temporal Dynamics of Streamflow Using Complex Networks

Bellie Sivakumar

Modeling the dynamics of streamflow continues to be highly challenging. The present study proposes a new approach to study the temporal dynamics of streamflow. The approach couples the concepts of complex networks and chaos theory. Applications of the concepts of complex networks for studying streamflow dynamics have been gaining momentum in recent years. A key step in such applications is the construction of the network – a network is a set of points (nodes) connected by lines (links). The present study uses the concept of phase-space reconstruction, an essential first step in chaos theory-based methods, for network construction to study the temporal dynamics of streamflow. The phase-space reconstruction involves representation of a single-variable time series in a multi-dimensional phase space using delay embedding. The reconstructed phase space is treated as a network, with the reconstructed vectors (rather than the original time series) serving as the nodes and the connections between them serving as the links. With this network construction, the clustering coefficient of the individual nodes and the entire network is calculated to assess the node and network strengths. The approach is employed to a large number of streamflow time series observed in the United States. The results indicate the usefulness and effectiveness of the phase-space reconstruction-based approach for network construction. The implications of the outcomes for identification of the appropriate type and complexity of model as well as for classification of catchments are discussed.

How to cite: Sivakumar, B.: Temporal Dynamics of Streamflow Using Complex Networks, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-14894, https://doi.org/10.5194/egusphere-egu2020-14894, 2020.

EGU2020-19626 | Displays | HS2.1.7

The Identification of Hydrological Threshold Variables

Arturs Veinbergs and Ainis Lagzdins

The threshold groundwater levels limiting the drainage depth and tile drain runoff as well as runoff recession and runoff partitioning are case-specific.  These are the characteristics that are usually necessary for setting up and calibration processes for such models as HYPE (Lindström et al. 2010) and SWAT (Neitsch et al. 2002).  

The objective of the present study is to identify the thresholds of groundwater levels and runoff rates that limit the formations of such runoff components as base flow and tile drain runoff. This study utilizes the data that represents the daily runoff measurements in open ditch with such characteristics as total length 2.4 km, basin area 368 ha, loamy soils, agricultural lands with subsurface drainage systems installed in 98% of the area, average tile depth 1.2m below ground surface.

The runoff components were partly separated from the daily runoff hydrographs through the analysis of storm runoff recession gradients (eq.1) and groundwater level fluctuations during the period from 2006. to 2015. Baseflow and tile drain runoff ware calculated as beeing linearly dependent on daily groundwater level fluctuations (eq.2).

  Rci=Qi+1/Qi,     (1)

Qx=fx(GWT)=ax*GWT+bx ,      (2)

Where: Rci – recession gradient; Qi and Qi+1– runoff of day i and i+1 respectively;  Qx – runoff component; GWT– groundwater level; ax and bx– slope and intercept of a linear function.

Nash-Sutcliffe efficiency (NSE) and percent bias (PBIAS) were used for comparison of calculated and separated runoff components.

The results indicate a decrease in drainage intensity and reduction in specific yield during the study period. The groundwater level of 1.18m below ground surface limit the existence of the tile drain runoff, that, furthermore,  is similar for rising and falling groundwater level. The results reveal that runoff could be contributed by 35%, 57% and 8% of baseflow, tile drain runoff and surface runoff respectively.

How to cite: Veinbergs, A. and Lagzdins, A.: The Identification of Hydrological Threshold Variables, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-19626, https://doi.org/10.5194/egusphere-egu2020-19626, 2020.

EGU2020-21451 | Displays | HS2.1.7

Changes of growing degree days in the main maize producing area of China during past years

Mengge Lu, Huaiwei Sun, and Shanzhen Yi

              The agricultural demands and supply were expected to grow all of the more severe with increasing population. Growing degree days is the dominant factors associated with the quality and quantity of many agricultural crops. In order to find out the effects of historical climate changes on agricultural production, we investigated the trends and changes of growth degree days (GDD) and heat degree days (HDD) in the main maize producing area of China by using the Inter-Sectoral Impact Model Intercomparison Project (ISIMIP) data. In this study, we find that the GDD and HDD increased slightly during 1861-2005 with more abruptly increases in GDD, which lead to better production environment in Central and Eastern China for maize. However, the climatic trend rates showed large variation in spatial, as GDD shows an upward trend in Hebei and Shandong provinces and HDD was on the rise in Shandong and Shanxi provinces. The GDD and HDD in the northern part of Hebei province and the northern part of Shanxi province are lower, but have a higher rising trend. Therefore, the future heat resources are better for maize production, but the risk of extreme high temperature is increased. This result indicates a necessary to the crop layout in these areas.

Appendix. List of figures

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

How to cite: Lu, M., Sun, H., and Yi, S.: Changes of growing degree days in the main maize producing area of China during past years, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-21451, https://doi.org/10.5194/egusphere-egu2020-21451, 2020.

HS2.1.8 – Zero flow: hydrology and biogeochemistry of intermittent and ephemeral streams

EGU2020-10912 | Displays | HS2.1.8

Nutrient and organic matter retention in the hyporheic zone during drying and rewetting in a mesocosm experiment.

Matthias Pucher, Thomas Hein, and Gabriele Weigelhofer

In intermittent streams, microbes in the sediments are challenged by extremely low water availability during dry periods. Microbes are responsible for the retention and degradation of nutrients. Reduced retention in headwaters can lead to nutrient and DOM accumulation in receiving downstream water bodies and can lead to eutrophication and algal blooms. Some research was done in Mediterranean regions, but we found little studies from temperate regions. There, droughts and water abstraction increased over the last years and caused sensitive headwater streams to shift from perennial to intermittent. In an experiment, we measured the effects of desiccation and re-wetting on nutrients (N, P) and dissolved organic matter (DOM) uptake by biofilms in the hyporheic zone. By that, we address two questions: (1) how do intermittent and perennial reaches differ in their response to desiccation and (2) which parameters can strengthen the resilience of hyporheic processes towards desiccation?

We performed a mesocosm experiment with sediments collected from 20 streams of 4 different regions in Austria. Both historically perennial and intermittent streams were sampled in each region. The sediments were filled into up-flow reactors and connected to a water supply to mimic conditions in the hyporheic zone. After an acclimatisation phase of 2 weeks and a dry period of 7 weeks, the sediments were rewetted. During the acclimatisation and the rewetting phase, we performed N, P and DOM plateau additions to measure the retention behaviour and the influence of drying on that behaviour. N was measured as NH4, NO2 and NO3, P as soluble reactive phosphate and DOM as dissolved organic carbon, via absorption parameters and via fluorescence parameters including a PARAFAC analysis. Additionally, we monitored the extracellular enzymatic activity, the water content and other sediment parameters.

We found that the low moisture content, that is left in sediments of temperate streams even after long drought periods, is sufficient for microbes to recover quickly afterwards. We measured a peak of nutrients and DOC right after rewetting. Nutrient and DOC retention was reduced immediately after rewetting, but recovered fast. We could not see any microbial adaption of historically intermittent streams to desiccation. Thus, differences between regions were much larger than those between perennial and intermittent streams. We can verify the results from our experiment by field data we collected in parallel.

Our study clearly highlights the necessity to protect hyporheic microbes from desiccation effects by ensuring enough moisture content during dry periods. Management methods, such as shading or a reasonable amount of residual flow, can ensure healthy biofilms and reduce effects of prolonged drought periods on in-stream nutrient retention.

How to cite: Pucher, M., Hein, T., and Weigelhofer, G.: Nutrient and organic matter retention in the hyporheic zone during drying and rewetting in a mesocosm experiment., EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-10912, https://doi.org/10.5194/egusphere-egu2020-10912, 2020.

EGU2020-22590 | Displays | HS2.1.8 | Highlight

Paying attention to the isolated pools phase in temporary rivers. A challenge to the ecological quality assessment of temporary rivers.

Núria Bonada, Francesc Gallart, Narcís Prat, Gisela Bertran, Miguel Cañedo-Argüelles, Núria Cid, Pau Fortuño, Joan Gomà, Cayetano Gutiérrez-Cánovas, Jérôme Latron, Pilar Llorens, Cesc Múrria, Maria Soria, Iraima Verkaik, and Dolors Viñoles

Temporary rivers are characterized by shifting habitats between flowing, non-flowing and dry phases. Despite the fact that they are currently receiving significant attention by researchers and managers, the non-flowing (standing pools) phase has been largely disregarded. However, isolated pools in temporary rivers are transitional habitats of major ecological relevance as they can act as refuges for maintaining local and regional freshwater biodiversity. Factors such as pool duration and size, local physicochemical conditions, time since disconnection, distance to other freshwater habitats or presence of predators are crucial for a comprehensive understanding of the ecology of these habitats, and compromise to work towards adequate ecological quality assessments and conservation practices in temporary rivers.

Research is ongoing focused on the development of a method for assessing the ecological status of disconnected pools, based on the relationship between the time elapsed after the pool disconnection and the characteristics of the biological communities taking into account the above-mentioned factors. The prevalence of the pool phase is assessed using the TREHS software tool through interviews with citizens as well as aerial and surface photographs examination. The time since disconnection is assessed with the help of low-cost sensors and water stable isotopes, whereas the local environmental characteristics are assessed using regular metrics. Finally, biological communities of the pools are characterized using both taxonomic and functional metrics, with the support of metabarcoding techniques, applied to diatoms, macrophytes, macroinvertebrates and fishes. This method aims to be used by water managers to improve the monitoring of the ecological status of temporary rivers, which are common around the world, harbor unique biodiversity and provide key ecosystem services.

How to cite: Bonada, N., Gallart, F., Prat, N., Bertran, G., Cañedo-Argüelles, M., Cid, N., Fortuño, P., Gomà, J., Gutiérrez-Cánovas, C., Latron, J., Llorens, P., Múrria, C., Soria, M., Verkaik, I., and Viñoles, D.: Paying attention to the isolated pools phase in temporary rivers. A challenge to the ecological quality assessment of temporary rivers., EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-22590, https://doi.org/10.5194/egusphere-egu2020-22590, 2020.

Temporary streams are common in headwater catchments and serve as important ecological and hydrological links between these catchments and downstream perennial rivers. However, our understanding of temporary streams in headwater catchments is limited due to a lack of high spatiotemporal resolution data of the three main hydrological states of these streams: dry streambed, standing water and flowing water. In this study, we used a custom designed multi-sensor monitoring system to collect high spatiotemporal resolution state data of the temporary streams in the 0.12 km2 upper Studibach catchment, a pre-alpine headwater catchment in Alptal, Switzerland. The monitoring system was installed at 30 locations in the stream network. The state data was used to determine: (1) the temporary stream regime for every monitoring location based on the permanence of each hydrological state, (2) the state change thresholds (antecedent soil moisture, precipitation amount and intensity, and discharge at the outlet) for every monitoring location, and (3) the state change patterns in the stream network during precipitation events. The temporary stream regimes, and the state change thresholds and patterns were compared to topographic, land cover and channel characteristics to determine if these factors can explain the variability in temporary stream dynamics. The results show that there are four different landscape areas with distinctive temporary stream dynamics in the catchment, and that a steep forested section with coarse streambed material often disconnects the flowing parts of the upper and lower stream network.

How to cite: Assendelft, R. and van Meerveld, I.: Spatiotemporal changes in the hydrological state of temporary streams in a pre-alpine headwater catchment, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-19965, https://doi.org/10.5194/egusphere-egu2020-19965, 2020.

EGU2020-11761 | Displays | HS2.1.8 | Highlight

Monitoring and modelling drainage network dynamics of a Mediterranean catchment

Alfonso Senatore, Alessio Liotti, Massimo Micieli, Nicola Durighetto, Gianluca Botter, and Giuseppe Mendicino

Empirical evidence indicates that the active part of the drainage networks, i.e. that characterized by flowing water, is not static but, conversely, it experiences significant expansion/contraction dynamics produced by the interactions between hydrological and climatic variability, morphological features and soil properties in the contributing catchment. The expansion and contraction dynamics of the "wet" component of the river network can be identified in a wide range of climatic conditions, particularly in the headwaters. In these areas, the observed river network dynamics largely depend on the capacity of the upstream drainage area to concentrate surface runoff in channelized sites.

The study presents a research activity carried out in the framework of the European project "DyNET: Dynamical River Networks" (http://www.erc-dynet.it/), specifically aimed at analysing in detail the processes and agents overseeing changes in form and in the length of river networks in a Mediterranean environment. The contribution describes the first results achieved in the southernmost of the basins under investigation in the DyNET project, namely the Turbolo creek catchment (Calabria, Southern Italy). Bi-weekly surveys were conducted in two sub-catchments having a total area of more than 1 km2, both during the recession (contraction) and reactivation (expansion) phases of the drainage network. The empirical data were used for the validation of a statistical model of the wet network dynamics, designed to estimate the total length of the active network over time. This length was distributed spatially on the river network in an objective way by defining a two-way relationship between active stream length and the Topographic Wetness Index (TWI). The modelling of the network contraction and expansion dynamics was possible using a few meteorological and hydrological variables. The combined use of information on the overall length of the network and the TWI led to a reasonably good representation of the drainage network dynamics over space and time.

How to cite: Senatore, A., Liotti, A., Micieli, M., Durighetto, N., Botter, G., and Mendicino, G.: Monitoring and modelling drainage network dynamics of a Mediterranean catchment, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-11761, https://doi.org/10.5194/egusphere-egu2020-11761, 2020.

EGU2020-8831 | Displays | HS2.1.8

Linking spatial heterogeneity of geomorphic properties, flow persistence and hydrological connectivity

Nicola Durighetto, Filippo Vingiani, Leonardo Enrico Bertassello, Matteo Camporese, and Gianluca Botter

Headwater drainage networks have a key role in the transport of water and nutrients from the uplands to the sea. The presence of intermittent and ephemeral tributaries makes the river network highly dynamical, with expansion-contraction cycles that are observed in response to precipitation variability. Both the drainage density and the dynamics of the river network, however, are spatially heterogeneous, reflecting the patterns of geomorphic and physiographic features of the contributing catchment. One of the major effects of river network dynamics is that the hydrological connectivity between a hillslope site and the outlet changes through time, with shorter unchanneled lengths and faster drainage pathways when the network is expanded.

Using the empirical data gathered in a small alpine catchment in northern Italy, we present some analyses about the heterogeneity in the river network persistence and the catchment hydrological connectivity under different flow conditions encompassing dry and wet periods. Different areas of the catchment exhibit very different drainage densities, mirroring the spatial heterogeneity in the geomorphological properties of the catchment. In particular, the most ephemeral stretches of the network are associated with thinner soil layers, steeper slopes, and shallow bedrocks, while the most persistent tributaries emerge in regions characterized by thicker soil layers and moraine deposits. The frequency distribution of the unchanneled lengths is used as a tool to characterize the hydrological connectivity between hillslope sites and the river network. Our results show that network expansion affects the length of unchanneled pathways in a very heterogeneous way, with local variations associated to changing hydrological conditions ranging from 0 to one kilometer. Furthermore, we show that the drainage density is more heterogeneous during wet conditions, with an increase in the spatial variability of the unchanneled length of about 20%. These results hint at the importance of studying intermittent and ephemeral streams to enhance the understanding of the hydrology and biogeochemistry of headwater catchments.

How to cite: Durighetto, N., Vingiani, F., Bertassello, L. E., Camporese, M., and Botter, G.: Linking spatial heterogeneity of geomorphic properties, flow persistence and hydrological connectivity, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-8831, https://doi.org/10.5194/egusphere-egu2020-8831, 2020.

EGU2020-3909 | Displays | HS2.1.8

Influence of Lithology, Climate and Topography on the duration of flow intermittence in Burkina Faso.

Axel Belemtougri, Agnès Ducharne, and Harouna Karambiri

The precise location of river streams and the characterization of their regime (intermittent or permanent) are critical to the quantification and management of water resources. Intermittent rivers are rivers that cease to flow or go completely dry at various times and places. Some studies estimated that intermittent rivers could account for more than 50% of all rivers in the world and are expected to increase in the future. There has been a growing interest in the understanding of these rivers ecosystems and the possible consequences of this increase in intermittency on the availability of water resources. In Burkina Faso in particular, a country located in West Africa and marked by a strong rainfall gradient between North and South (600 to 1200 mm/y), intermittent streams often represent, in some areas, the only significant freshwater source available for irrigation. It is therefore necessary to develop knowledge and understand the factors controlling intermittency in order to define adequate means to preserve and protect rivers. This study aims to identify non-redundant environmental variables that best explain the geographic variations of the hydrological regime of rivers, and in particular the duration of intermittency, and to discuss their interactions. For this purpose, 40 gauging stations are taken into account in the study. The catchments controlled by these stations cover more than 50% of the country territory. The mean number of dry months was used as a predictor to define several classes of intermittence, for which explicit environmental variables were identified through a Principal Component Analysis (PCA). Results suggest that lithology is a crucial and logical control of intermittency in Burkina, with some stations classified as permanent (43%) mostly located on sedimentary and carbonate rocks, whereas the remaining stations classified as intermittent are mostly located on metamorphic rocks. There is also an increasing trend in the number of dry months depending on the aridity index, although contrasted by the underlying lithology and the catchment area. This approach may subsequently be extended to other African countries in order to consolidate our results.

How to cite: Belemtougri, A., Ducharne, A., and Karambiri, H.: Influence of Lithology, Climate and Topography on the duration of flow intermittence in Burkina Faso., EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-3909, https://doi.org/10.5194/egusphere-egu2020-3909, 2020.

Intermittent headwater catchments constitute a significant proportion of many stream networks. In semi-arid climates, intermittent headwater streams flow only following periods of sustained rainfall. There is commonly a rapid response of streamflow to rainfall; however, whether this is the input of recent rainfall or displacement of water stored in the catchments for several years is not well known. Understanding the sources and transit times of water that contribute to streamflow is important for the maintenance of stream health and predicting the response of land-use changes.

The study focuses on two intermittent streams from two contrasting land-use (pasture and forest) in southeast Australia. The native eucalyptus forests in this region were originally cleared for grazing following European settlement ~180 years ago and then partially replaced by plantation in the last ~15 years. Stream water and groundwater from the riparian zone adjacent to the streams were sampled between May and October 2018.

The stream water has 3H activities of 1.30 to 3.17 TU in the pasture and 1.84 to 3.99 TU in the forest, with higher activities recorded during the higher winter flows. Groundwater from the riparian zone has 3H activities of 0.16 to 0.79 TU in the pasture and 2.01 to 4.10 TU in the forest. Aside from one riparian zone groundwater sample, all 3H activities of groundwater in the riparian zone are lower than those of recent local rainfall (~2.79 TU). The single high 3H activity in riparian zone possibly reflects recharge by winter rainfall with higher 3H activities.

The mean transit times (MTTs) of water were estimated using a range of tracer lumped parameter models. The riparian zone groundwater has greater MTTs of hundreds of years in the pasture and up to 9 years in the forest. At high streamflow, the stream water has MTTs of <6 years in the pasture and the forest. The MTTs of stream water at low streamflow vary from 15 to 42 years in the pasture and from 3 to 16 years in the forest. The long MTTs of water from streams indicate that the source water is not just recent rainfall, rather water stored in the riparian zone is mobilised at the commencement of flow and recent rainfall makes a larger contribution at higher flows. The observation is consistent with the major ion geochemistry of the stream water, which most closely represents that of the riparian zone groundwater. The differences in MTTs of stream water between two contrasting land-use imply that the streamflow has been being most likely impacted by land-use changes. Thus, it is necessary to improve the strategies for catchment management to protect stream health from land-use practices.

How to cite: Barua, S., Cartwright, I., Daly, E., and Morgenstern, U.: Understanding the sources and transit times of water contributing streamflow from intermittent headwater catchments in semi-arid areas, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-2030, https://doi.org/10.5194/egusphere-egu2020-2030, 2020.

EGU2020-15218 | Displays | HS2.1.8

Statistical modelling of intermittence metrics in temporary rivers of the UK

Michael Eastman, Simon Parry, Catherine Sefton, and Cecilia Svensson

Temporary rivers (TRs) are important headwater features of river flow networks, varying dynamically in space and time and providing both terrestrial and freshwater habitats.  In parts of the UK, TRs have become a source of tension between the public and regulators against a backdrop of the competing influences of natural variability, climate change and artificial influences.  Despite this importance, such systems have typically been omitted from monitoring endeavours.  Correspondingly, the occurrence, distribution and characteristics of TRs in the UK are poorly understood.  An enhanced understanding of the features of TRs has the potential to underpin more robust evidence for the protection of aquatic habitats that are vulnerable to drying.

In this study, novel approaches to the statistical modelling of TRs in the UK are adopted to enable the simulation of intermittence metrics. Addressing the challenge of limited observational data, models are trained on data from both the UK and France, drawing on their temporal and spatial advantages, respectively, to maximise their robustness and ability to extrapolate spatially. The performance of a range of statistical modelling and machine learning approaches is evaluated, and applied in simulating intermittence metrics in the UK. 

Preliminary validation results suggest that the modelling approaches are able to replicate observed intermittence metrics where data exist.  Hierarchies of modelling approaches are derived which suggest certain families of models are more effective in simulating flow intermittency in TRs.  The best performing models under validation are taken forward to simulate intermittence patterns beyond networks of observations, helping to identify core regions towards which further focus should be directed by the research and operational TR communities.

Information on the location, prevalence and intermittency of TRs is vital to enhance the efficiency of monitoring strategies with finite resources, and bolster community efforts to engage local stakeholders in gathering additional data.

How to cite: Eastman, M., Parry, S., Sefton, C., and Svensson, C.: Statistical modelling of intermittence metrics in temporary rivers of the UK, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-15218, https://doi.org/10.5194/egusphere-egu2020-15218, 2020.

EGU2020-21214 | Displays | HS2.1.8

Characterising transition towards more ephemeral streams in Australian catchments

Margarita Saft, Murray Peel, and Tim Peterson

Many streams experienced a prominent increase in proportion of cease to flow conditions during and after the multiyear drought in Australia (Millennium drought, circa 1997 – 2009). Change in zero flow occurrence frequency reflects the general transition of stream reaches from gaining to losing conditions, from losing to losing more, and ultimately to the disconnected state. We track and characterise these changes in groundwater-surface water connection using zero flow conditions as a proxy and explore the spatial and temporal patterns in flow regime transformation. The implications for upstream / downstream water availability and management of environmental flows and ecosystems are discussed in view of projected drier future climate.

How to cite: Saft, M., Peel, M., and Peterson, T.: Characterising transition towards more ephemeral streams in Australian catchments, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-21214, https://doi.org/10.5194/egusphere-egu2020-21214, 2020.

EGU2020-22542 | Displays | HS2.1.8 | Highlight

Potential flow regime alterations under climate change in an intermittent river system

Anna Maria De Girolamo and Antonio Lo Porto

The potential impact of climate change on the flow regime was analyzed for the Celone River, an intermittent river system in the Apulia Region (S_E, Italy). Rainfall and temperature recorded in the past century were analyzed. Flow regime under climate projections for the future (2030–2059) and for the recent conditions (1980–2009) were compared. The Soil and Water Assessment Tool, a hydrological model, was used to simulate daily streamflow in selected river sections.

Daily climate data used to simulate future scenarios were obtained by a combination of a global circulation model (GCM, ECHAM5) and different regional models (RACMO2; RCA; REMO). The impact on the hydrological regime was estimated as a deviation from the baseline (1980–2009) by using a number of indicators of hydrological alterations.

From 1919 to 2012, a slight reduction in total annual rainfall and a decrease of the number of rainy days was recorded, hence, an increase in extreme rainfall events. From 1954 to 2012, the minimum daily temperature in January and February increased reducing the snowfall.

Under future scenarios, an increase in mean temperature was predicted for all months between 0.5–2.4 °C and a reduction in precipitation (by 4–7%). As a consequence, the flow regime moves towards drier conditions and the divergence of the flow regime from the current conditions increases in future scenarios, especially for those reaches classified as I‐D (ie, intermittent‐dry) and E (ephemeral).

Hydrological indicators showed an extension of the dry season and an exacerbation of the extreme low flow conditions with a decrease in both high flow and low flow magnitudes for various time durations. These changes are expected to have several implications for river ecosystems that have to be considered in River Basin Management and Planning.

How to cite: De Girolamo, A. M. and Lo Porto, A.: Potential flow regime alterations under climate change in an intermittent river system, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-22542, https://doi.org/10.5194/egusphere-egu2020-22542, 2020.

EGU2020-9420 | Displays | HS2.1.8

Assessing flow intermittence in France under climate change

Aurélien Beaufort, Quentin Bottet, Guillaume Thirel, and Eric Sauquet

With climate change, perennial headwater streams are expected to become intermittent and intermittent rivers to dry more often due to more severe droughts, placing additional stress on aquatic life and new constraints for water management.

In this study, we quantify the changes in river flow intermittence across France over the 21st century. Using global hydrological model calibrated on gauging stations is certainly hazardous to assess changes in flow intermittence at a fine resolution (i.e. in headwater streams). Here, we suggest a modelling framework supported by field observations performed on a large number of French intermittent streams:

- we used discrete observations from the ONDE network set up by the French Biodiversity Agency recording summer low‐flow levels once a month. ONDE sites are located on headwater streams with a Strahler order strictly less than five and evenly distributed throughout France;

- a model developed by Beaufort et al. (2017) was adapted to simulate the regional probability of drying of headwater streams (RPoD) under climate change. This empirical model is based on regional relationships established between the non-exceedance frequencies of daily discharges and the proportion of drying statuses observed at ONDE sites. Calibration was performed against the discrete flow states available at 3300 ONDE sites between May and October from 2012 to 2018. The model used daily discharges simulated at 568 gauging stations by the GR6J rainfall-runoff model (Pushpalatha et al., 2011).

An ensemble of 26 high-resolution projections has been derived from GCM simulations under RCP2.6 and RCP8.5 emission scenarios, applying an advanced delta change approach (van Pelt et al., 2012). Daily discharge time series at the 568 gauging stations obtained from GR6J with the GCM-driven forcings have been used as inputs of the empirical model to estimate RPoD under future climate conditions.

Characteristics of flow intermittence between May and October have been studied over France divided into 22 Hydro-EcoRegion. Results for the periods 2021-2050 and 2071-2100 show an increase in RPoD with time. The mean RPod over the whole period May–October is 12% at the national scale under the current climate, compared to 20% and 23% on average all RCPs together for the periods 2021-2050 and 2071-2100, respectively. The changes are significant in regions with historically high probability of drying. On the other hand, no change is detected in the Alps. This last result is debatable since, in these areas and under the current climate, low flows are mostly observed in winter, the ONDE sites are sparse and the model predicting RPoD shows the worst performance.

References:

Beaufort et al.: Extrapolating regional probability of drying of headwater streams using discrete observations and gauging networks, Hydrol. Earth Syst. Sci., 22(5), 3033–3051, 2018.

Pushpalatha et al.: A downward structural sensitivity analysis of hydrological models to improve low-flow simulation, J. Hydrol., 411, 66–76, 2011.

van Pelt et al.: Future changes in extreme precipitation in the Rhine basin based on global and regional climate model simulations, Hydrol. Earth Syst. Sci., 16, 4517–4530, 2012.

How to cite: Beaufort, A., Bottet, Q., Thirel, G., and Sauquet, E.: Assessing flow intermittence in France under climate change, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-9420, https://doi.org/10.5194/egusphere-egu2020-9420, 2020.

EGU2020-1790 * | Displays | HS2.1.8 | Highlight

An EU-wide citizen science network to monitor hydrological conditions in intermittent rivers and ephemeral streams

Eric Sauquet, Ilja van Meerveld, Cath Sefton, Josep Fortesa, Helena Ramos Ribeiro, Iakovos Tziortzis, Anna Maria de Girolamo, July England, Joan Estrany, Pau Fortuño, Antoni Munné, Zoltan Csabai, Manuela Morais, Helena Alves, and Thibault Datry

Studying Intermittent Rivers and Ephemeral Streams (IRES) requires regular observations of streamflow. Unfortunately, intermittent streams are poorly monitored, particularly in temperate climates. To fill gaps in knowledge of the dynamics of intermittent streams, a pilot initiative within the SMIRES project (Datry et al., 2017, https://www.smires.eu/) was launched in April 2019. This initiative invited citizens to submit observations for a large number of European intermittent streams.

The goal was collecting datasets that can be used in robust scientific inquiries:

-             To identify IRES at the European scale. Everyone was encouraged to report the flow state for any stream in Europe at any time during 2019;

-             To investigate the dynamics of flow intermittence by repeating field observations along an IRES at least once each month and if possible at multiple locations.

The CrowdWater app (https://crowdwater.ch/en/crowdwaterapp-en/) was used to collect the observations. Each contributor was asked to take a picture of the stream and to identify the current flow state of the stream as one of six classes, from “dry” to “flowing”. The citizen science network has collected, in eight months, more than 3500 observations in ~500 river reaches across 15 countries.

In this presentation, we will discuss the benefits and the limitations of this citizen science effort (i.e., how these data complement the information provided by gauging stations, how and why the collected data were used by the main contributors, how participants can be engaged in the long-term etc.). We will compare the success of this international initiative to other regional or local scale initiatives.

References:

Datry, T., Singer, G., Sauquet, E., Jorda-Capdevilla, D., Von Schiller, D., Subbington, R., Magand, C., Pařil, P., Miliša, M., Acuña, V., Alves, M., Augeard, B., Brunke, M., Cid, N., Csabai, Z., England, J., Froebrich, J., Koundouri, P., Lamouroux, N., Martí, E., Morais, M., Munné, A., Mutz, M., Pesic, V., Previšić, A., Reynaud, A., Robinson, C., Sadler, J., Skoulikidis, N., Terrier, B., Tockner, K., Vesely, D., Zoppini, A (2017) Science and Management of Intermittent Rivers and Ephemeral Streams (SMIRES). Research Ideas and Outcomes 3: e21774. https://doi.org/10.3897/rio.3.e21774

How to cite: Sauquet, E., van Meerveld, I., Sefton, C., Fortesa, J., Ramos Ribeiro, H., Tziortzis, I., de Girolamo, A. M., England, J., Estrany, J., Fortuño, P., Munné, A., Csabai, Z., Morais, M., Alves, H., and Datry, T.: An EU-wide citizen science network to monitor hydrological conditions in intermittent rivers and ephemeral streams, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-1790, https://doi.org/10.5194/egusphere-egu2020-1790, 2020.

HS2.2.1 – Models and Data: Understanding and representing spatio-temporal dynamics of hydrological processes

EGU2020-7691 * | Displays | HS2.2.1 | Highlight

A historical database of key hydroclimatic variables in and across 6400 catchments around the world

Navid Ghajarnia, Zahra Kalantari, and Georgia Destouni

Availability of historical hydroclimatic data for different climate regions is necessary for hydrological change modeling and analysis. Nowadays, many global products are available that provide hydrological and meteorological datasets based on direct measurements, remote sensing observations, re-analysis outputs, and model simulations. However, differences in spatial and temporal resolutions, and inconsistencies seen between observed hydrological patterns and different model results and datasets makes it difficult to choose an appropriate combination of data products for hydrological studies. This study provides a new combined historical database of five key hydroclimatic variables at monthly and daily scales, obtained from different observational and re-analysis global datasets, including runoff (R; from GSIM), precipitation (P; from GPCC-V7 and ERA5), evapotranspiration (ET; from GLEAM 3.3 and ERA5), soil moisture (SM; from ESACCI-v04.5, GLEAM 3.3 and ERA5), and temperature (T; GHCN-CAMS, ERA5). The new database combines these variables for each of 6,400 catchments of different scales around the world. In order to select the catchments, the existing nearly 35,000 streamflow time series in the GSIM database was analyzed and 8,400 catchments were selected based on the criterion of having at least 25 years of monthly runoff data available from 1980 to 2010. After further quality controls on the accuracy of catchment polygons, and reported catchment areas and stream flows, and consistency of the range, average values, and variations of variables time series, the 6,400 catchments were selected for the final development of the new catchment-related database in this study. The other hydroclimatic variables, besides runoff, are also spatially aggregated for each individual catchment and corresponding catchment-average time series are produced from 1980 to 2019. The final database thus provides a collection of long-term multi-climate and multi-catchment time series of the five key hydroclimate variables, aggregated over each of the 6,400 hydrological catchments around the world. In choosing the data sources for each variable, first priority was given to direct observational datasets (available for all variables except for the ET), and further to re-analysis outputs that many researchers regard as being close to directly observed data. The database developed in this study can be used for different types of studies on hydrology, water resources, and their changes under shifting climate and land use conditions in different parts of the world. The standardized format of this database ensures easy applicability with possibility of expansion to include more and other types of data, e.g., on land use/cover types and their changes, and on other climatic, geomorphologic, and anthropogenic conditions.

How to cite: Ghajarnia, N., Kalantari, Z., and Destouni, G.: A historical database of key hydroclimatic variables in and across 6400 catchments around the world, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-7691, https://doi.org/10.5194/egusphere-egu2020-7691, 2020.

EGU2020-11348 | Displays | HS2.2.1 | Highlight

Advances in using radar to observe vegetation water dynamics

Susan Steele-Dunne, Paul Vermunt, Saeed Khabbazan, Ashwini Petchiappan, Jasmeet Judge, Mariette Vreugdenhil, Sebastian Hahn, and Wolfgang Wagner

Vegetation acts as an interface between the earth's surface and the atmosphere, modulating exchanges of water, carbon and energy and responding to environmental stressors. Improved understanding of water transport through the soil-vegetation-atmosphere continuum is essential to understand the role of vegetation at a catchment and a global scale. The sensitivity of radar remote sensing observations to the water content of soil and vegetation makes it well-suited to monitoring spatio-temporal dynamics of processes in the soil-vegetation-atmosphere continuum.

Here, we present the latest results from studies using ground-based and spaceborne radar demonstrating the potential of radar to monitor vegetation water dynamics at scales from meters to tens of kilometers. Field data will be used to demonstrate the sensitivity of radar observations to surface and internal vegetation water content. These results illustrate the potential value of radar for monitoring rapid plant water dynamics, and the impact of water-limited conditions on land-atmosphere exchanges. Satellite data will be used to illustrate the degree to which current spaceborne radar systems can already be used to monitor these processes and the limitations posed by revisit time and resolution.

We will conclude with an outline of future opportunities and challenges. The next generation of spaceborne radar sensors offers  unprecedented monitoring capability. To avail of this opportunity, we need improved alignment between the treatment of vegetation in hydrological and radiative transfer models. This is essential to ensure meaningful relationships between new radar data products and hydrological states of interest, and to facilitate the assimilation of radar observations to constrain vegetation processes in hydrological models.

How to cite: Steele-Dunne, S., Vermunt, P., Khabbazan, S., Petchiappan, A., Judge, J., Vreugdenhil, M., Hahn, S., and Wagner, W.: Advances in using radar to observe vegetation water dynamics, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-11348, https://doi.org/10.5194/egusphere-egu2020-11348, 2020.

EGU2020-19769 | Displays | HS2.2.1

Improving hydrologic model realism by using stable water isotopes

Harsh Beria, Lionel Benoit, Natalie Ceperley, Anthony Michelon, Joshua R. Larsen, Grégoire Mariéthoz, and Bettina Schaefli

The last century of hydrological research has led to significant improvements in representing different hydrological processes in rainfall-runoff models. With widely available streamflow data, such models are typically calibrated against this reference time series, which can limit their predictive power. One option to improve the realism of rainfall-runoff models is by incorporating environmental tracers such as stable isotopes of water, water temperature and electrical conductivity within the modeling setup. Conventionally, stable water isotopes have been used to learn more about the dominant hydrological processes that occur within a given catchment, which generally helps improve the hydrologic model structure, but often at the cost of increased model complexity to simulate the tracer concentration along with streamflow.

In this study, we develop a framework to incorporate stable water isotopes in continuous hydrological modeling, without significantly increasing model complexity. In the first step, stable water isotopes are used along with streamflow recession analysis to initialize the model state variables. After that, a Bayesian mixing model is used to infer the proportion of slow vs fast subsurface flow, and the results are used as additional constraints during the model calibration. This framework is extensively tested in a snow-dominated experimental catchment called Vallon de Nant, located in the Southwestern Swiss Alps (1189-3051 m. a.s.l.). During the presentation, we will discuss the advantages and limitations of such a modeling approach and how it can be extended to other experimental catchments.

How to cite: Beria, H., Benoit, L., Ceperley, N., Michelon, A., Larsen, J. R., Mariéthoz, G., and Schaefli, B.: Improving hydrologic model realism by using stable water isotopes, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-19769, https://doi.org/10.5194/egusphere-egu2020-19769, 2020.

EGU2020-333 | Displays | HS2.2.1

Cross-scale insights into flow and nutrient dynamics through coupled tracer-aided ecohydrological and biogeochemical modeling

Xiaoqiang Yang, Doerthe Tetzlaff, Chris Soulsby, and Dietrich Borchardt

Stable isotope tracers in water (e.g., 2H and 18O) have recently been widely used in soil-plant-atmosphere-continuum studies to quantify storage-flux-age interactions, mixing processes and the partitioning of precipitation into evaporation and plant transpiration, as well as groundwater recharge and runoff generation. Tracer-aided ecohydrological modeling can explicitly capture the role of vegetation dynamics in these processes, and constraining models using tracers can provide more realistic representation of water flow paths and ages. Such constraints are of particular importance in the context of catchment nutrient modeling, which integrates conservative hydrological mixing and reactive ecological and biogeochemical processes. Therefore, coupled tracer-aided modeling of ecohydrology and water quality has the potential to improve our understanding of catchment functioning and provide an evidence base for managing environmental trends under changing anthropogenic pressures. Moreover, in the domain of process-based modeling, fully distributed models have been shown to be advantageous in terms of efficiently capturing the high heterogeneity of natural and anthropogenic controls, and linking the modeling efforts with multiple data sources at different scales.

In this project, we apply advanced isotope-based modeling concepts to the intensively monitored TERENO - Bode catchment (ca. 3300 km2), which exhibits high gradients of hydroclimate, geology and landscape characteristics, and has associated anthropogenic impact gradients. We firstly focused on a well-studied, agricultural sub-catchment (Schäfertal, 1.44 km2). Rich data sets of long-term, high-frequency hydrometeorological conditions, vegetation dynamics, isotopes and agricultural management practices were integrated into the new tracer-aided ecohydrological model EcH2O-iso, which here is further coupled with the nitrate turnover and transport routines from the new mHM-Nitrate model. The flexible, fully distributed structure of the coupled model allows in-deep, extensive investigation of flow, tracer and nitrate dynamics across scales. Measurements at different spatial scales and under contrasting flow conditions (from lysimeter plots to the catchment monitoring network) were integrated for multi-criteria calibration in order to test and improve the model. The initial modeling in the small headwater catchment opens new opportunities for future upscaling investigations based on the hierarchical monitoring settings in the Bode catchment (from plots to headwaters, and to nested catchments (from ca. 100 to 3000 km2)).

How to cite: Yang, X., Tetzlaff, D., Soulsby, C., and Borchardt, D.: Cross-scale insights into flow and nutrient dynamics through coupled tracer-aided ecohydrological and biogeochemical modeling, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-333, https://doi.org/10.5194/egusphere-egu2020-333, 2020.

Complex models suffer from a multiplicity of parameters, allowing many combinations of values to yield apparently acceptable results and thus entailing a risk of obtaining “right answers for wrong reasons”. Aiming to compute key components of the water and energy balances from readily available meteorological observations while reducing the need for free parameters, we propose new formulations to extend the SPLASH model of Davis et al. (2017, Geoscientific Model Development) to deal with complex topography. SPLASH is a parsimonious, multi-purpose set of algorithms designed principally for ecological and ecohydrological applications. Wherever possible we based model construction on first principles, attempting to balance realism with robustness. By adopting analytical rather than numerical solutions for many processes, we have been able to apply the model at high spatial resolution without unreasonably inflating computational demands – allowing us to include terrain effects directly in the calculations of water and energy fluxes. Slope and aspect were included in the analytical integrals originally used to compute accumulated energy fluxes through the day. Upslope area, the terrain-induced hydraulic gradient, and an analytical solution for the soil column transmittance were included in the calculations of subsurface water flow, following TOPMODEL ideas. Whenever empirical calculations were used (pedotransfer functions, albedo-snow cover functions), they were recalibrated using a combination of remote sensing data and globally distributed observational datasets. Simulations of soil water content, evapotranspiration and snow-water equivalent were compared against in situ measurements using diverse and combined data sources (including FLUXNET and SNOTEL). The statistical performance of the model was tested with pooled measurements from multiple stations. Global simulations were run at 5 km resolution and compared with remote-sensing retrievals and state-of-the-art land surface models.

How to cite: Sandoval, D. and Prentice, I. C.: Simple process-led algorithms for simulating habitats (SPLASH v.2.0): robust calculations of water and energy fluxes in complex terrain, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-5073, https://doi.org/10.5194/egusphere-egu2020-5073, 2020.

EGU2020-1095 | Displays | HS2.2.1

The impact of thermokarst lakes on streamflow generation in Central Yakutia (Russia): data assessment and modelling

Olga Makarieva, Nataliia Nesterova, Alexander Fedorov, and Andrey Shikhov

Central Yakutian Plain (Russia) is situated in Eastern Siberia in the Lena River basin and is characterized by severe continental climate, continuous permafrost and flat relief. The combination of semi-arid climate, gentle topography and ice-rich permafrost provides favorable conditions for the development of thermokarst lakes. Poorly developed river drainage system and the distribution of thermokarst lakes within the river basins form the areas with internal drainage which contribute runoff to river network only in wet conditions. The results of such environment are the special hydrological regime of the region which is characterized by extreme seasonal and annual variability of streamflow.

In this project we study the hydrological processes in four rivers of Central Yakutia with the basin area from 1270 to 8290 km2 and available long-term streamflow data. Thermokarst lakes take up to 5-10 % of the area of those basins. Annual precipitation of this area is about 240 mm, while average annual streamflow varies from 1 to 15 mm depending on the river basin. Due to climate warming the number and area of thermokarst lakes in Central Yakutia is increasing (Kravsova, Tarasenko, 2011). The aim of the project is to investigate the impact of thermokarst lakes on hydrological regime and provide some reasonable projections of its changes in the future. Previous study (Lebedeva, 2018) has shown that the results of streamflow simulations in this region based on standard hydrological modeling approach were not satisfactory.

We used remote sensing data (Landsat images) to assess the seasonal and annual variation of thermokarst lakes area and their contributing area and combined that data with hydrological modelling of runoff formation processes. The hydrological model Hydrograph (Vinogradov et al., 2011) was applied in this study. The model contains the algorithms of heat and moisture dynamics in the upper part of soil profile which allow its use in the permafrost conditions. New part of the model algorithm was developed which considers the variations of thermokarst area depending on meteorological conditions, evaporation from open water areas and the dynamic of surface runoff retention depth. These model improvements allowed for the satisfactory results in streamflow simulations for historical period and future projections. In general, with the future development of thermokarst lakes in Central Yakutia one may expect the decrease of annual streamflow and its higher variation from one year to another.

Th results of the study will be presented. The study was funded by RFBR, project number 19-35-50030.

How to cite: Makarieva, O., Nesterova, N., Fedorov, A., and Shikhov, A.: The impact of thermokarst lakes on streamflow generation in Central Yakutia (Russia): data assessment and modelling , EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-1095, https://doi.org/10.5194/egusphere-egu2020-1095, 2020.

Measurements and models constitute the core modes of understanding environmental processes, where a major paradigm of doing science involves confronting hypotheses (represented by models) with data from measurements. Of course, both models and measurements involve uncertainties which can make reasoning about the validity of our hypotheses difficult. This difficulty is exemplified in the study of turbulent heat fluxes where measurements made by eddy-covariance towers often have energy balance gaps and simple regression models often outperform the most sophisticated physically-based models. Our study addresses these issues by identifying the conditions in which either or both models and measurements break down as well as identify potential reasons for these breakdowns.

We use the Structure for Unifying Multiple Modeling Alternatives (SUMMA) to develop an ensemble of models representing multiple hypotheses about how turbulent heat fluxes are generated and compare them against measurements from FluxNet towers at a number of hydro-climatically diverse sites. We evaluate the models against the measurements using both traditional error measures as well as with a general framework based on information theory and conditional probabilities. Extending this base analysis, we compute conditional mutual information of the modeled and observed relationships between turbulent heat fluxes and other meteorological variables (such as shortwave radiation, air temperature, and humidity). This allows us to go further than traditional error measures to explore how well the modeled relationships match the observed, providing a proxy for process correctness. We perform this analysis for a variety of conditions. We first analyze how much information the meteorological variables provide to the observed heat fluxes to estimate the robustness of the measurements. We then compare this with the amount of information that the meteorological variables provide to the simulations to determine whether there are significant deviations between the shared information from the simulations to the observations. This analysis is used to provide recommendations for post processing observations as well as identifying possible process deficiencies in our models.

How to cite: Bennett, A. and Nijssen, B.: Hard to measure, hard to model: Using information theory to understand turbulent heat fluxes, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-5957, https://doi.org/10.5194/egusphere-egu2020-5957, 2020.

EGU2020-11347 | Displays | HS2.2.1

Analytical upscaling of fill-and-spill hydrology

James Craig, Mahkameh Taheri, and Mark Ranjram

Fill-and-spill hydrology, where landscape storage features such as bogs, lakes, prairie sloughs, or surface depressions impound and then dynamically release water after a deficit is filled, has received increased attention in recent years. In systems dominated by fill-and-spill, the contributing runoff area is a function of both local storage deficit and the degree and nature of connectivity between storage features. Here, a closed-form analytical upscaled probabilistic event model of runoff response from thousands of bog cascades in a wetland complex is developed and demonstrated. The efficient mathematical model represents the individual wetland contributing area, runoff coefficient, and pre-event deficit of each bog as probability distributions that may be estimated via a combination of spatial analysis and field observation.

The model is here used to explore the impacts of cascade depth, network branching ratio, local contributing area, and deficit distribution on runoff response. The upscaling results provide insight into the critical runoff characteristics and emergent behaviour of watersheds typified by fill-and-spill hydrology and clarify the role of ‘gatekeeper’ storage features at large scales and for systems with shallow cascade depth. The mathematical solution is found to be a generalization of the well-known PDM (Probability Distributed Model) and Xinanxiang probabilistic runoff models for the specific case where network depth is one and contributing area of each storage feature is zero, and therefore can be readily generalized to support simulation of classical rainfall-runoff responses in heterogeneous landscapes. The results of the model enable exploration of scaling and distribution effects upon catchment runoff in basins influenced by fill-and-spill hydrology.

How to cite: Craig, J., Taheri, M., and Ranjram, M.: Analytical upscaling of fill-and-spill hydrology, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-11347, https://doi.org/10.5194/egusphere-egu2020-11347, 2020.

EGU2020-10655 | Displays | HS2.2.1

Effects of microtopography across spatial scales: studying hydrological response through high-resolution shallow-water modelling

Mario Morales-Hernandez, Ilhan Özgen-Xian, and Daniel Caviedes-Voullième

Microtopography is recognised as one of the morphological features which controls runoff generation, surface hydrodynamics, and surface runoff hydrological response. The spatial scales of microtopography are orders of magnitude smaller than typical hydrological domains such as hillslopes or catchments. The hydrodynamic response in the presence of microtopography  is complex and its impact on hydrological behaviour is inherently a multiscale problem, influenced by a number of processes and features. In particular, the geometrical properties of microtopography, and the ponded volume in relation to rainfall volume play a role at the micro and meso scales, while the hydrological response at a larger “macro” scale depends on how large such spatial macroscale is: at sufficiently small scales, the hydrological response is ill-defined; at very large scales, microtopography may not be relevant. Yet, at some intermediate scales, the hydrological dynamics can be strongly dominated by microtopography.

In this work, a state-of-the-art, high-performance shallow water solver is used to simulate rainfall-runoff processes on an idealised catchment, at a spatial resolution which explicitly and completely resolves microtopography.  For simplicity, microtopography is modelled as a 2D sine wave, which is superimposed on a planar hillslope. A four-dimensional parameter space is explored, defined by different slopes, different amplitudes and wavelengths for the microtopography, and different rainfall events. The large parameter space, together with the high resolution and the inherent cost of the solver result in a very large computational cost. In consequence, we implement SERGHEI, a parallelised, high-performance shallow water equations solver based on the Kokkos programming framework. SERGHEI enables computations on heterogeneous systems and multiple graphics processor units (GPU), which allows to address very large computational studies such as this one.

Rainfall-runoff-infiltration partitioning is evaluated in terms of runoff, infiltration and ponding volumes, as well as in terms of a contingency table of flooded surfaces for a reference smooth surface and a set of rough surfaces with microtopography. The results are compared both globally (for the entire domain) and in a spatially-distributed manner in order to assess at which spatial scales the hydrodynamic heterogeneity manifests itself as an emergent hydrological behaviour. The preliminary results show a non-linear response of hydrological signatures to the different parameters, and a complex dependency across scales.

How to cite: Morales-Hernandez, M., Özgen-Xian, I., and Caviedes-Voullième, D.: Effects of microtopography across spatial scales: studying hydrological response through high-resolution shallow-water modelling, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-10655, https://doi.org/10.5194/egusphere-egu2020-10655, 2020.

EGU2020-9514 | Displays | HS2.2.1

Modeling the effect of flood and drip irrigation on groundwater recharge

Sandra Pool, Félix Francés, Alberto Garcia-Prats, Cristina Puertes, Manuel Pulido-Velázquez, Carles Sanchis-Ibor, Mario Schirmer, Hong Yang, and Joaquín Jiménez-Martínez

Irrigation modernization, here defined as the replacement of traditional flood irrigation systems by pressurized drip-irrigation technology, has been widely promoted with the aim to move towards a more sustainable use of freshwater resources in irrigated agriculture. However, the scale sensitivity of irrigation efficiency challenged the predominantly positive value attributed to irrigation modernization and asked for an integrated evaluation of the technological change at various scales. The aim of this study is therefore to contribute to an improved understanding of the hydrological functioning in a landscape under irrigation modernization. We used local field observations to propose a regional scale modeling approach that allowed to specifically simulate the difference in water balance as a function of irrigation method and crop type. The approach focused on the modification of the spatial input data and had therefore the benefit of being relatively independent of the final choice of the hydrological model. We applied the proposed approach to the semi-arid agricultural area of Valencia (Spain), where regional information about the use of irrigation technologies and irrigation volumes at farm level were available. The distributed hydrological model Tetis was chosen to simulate the daily water balance from 1994 to 2015 for an area of 913 km2 at a spatial resolution of 200 m. Model simulations were based on a random selection of parameter values that were subsequently evaluated in a multi-objective calibration framework. Multiple process scales were addressed within the framework by considering the annual evaporative index, monthly groundwater level dynamics, and daily soil moisture dynamics for evaluation. Simulation results were finally analyzed with a focus on groundwater recharge, which is of particular interest for environmental challenges faced within the study area. Simulation results of groundwater recharge for the entire agricultural area indicated a considerable variability in annual recharge (values from 112 mm up to 337 mm), whereby recharge was strongly controlled by annual rainfall volumes. Annual recharge in flood-irrigated areas tended to exceed annual recharge in drip irrigated-areas except for years with above average rainfall volumes. The observed rainfall dependency could be explained by the fact that recharge in drip-irrigated areas almost exclusively occurred during rainy days, whereby a few heavy rainfall events could produce the majority of annual recharge. Our results indicated interesting differences but also commonalities in groundwater recharge for flood and drip irrigation, and therefore emphasized the importance of explicitly considering irrigation technology when modelling irrigated agricultural areas.

How to cite: Pool, S., Francés, F., Garcia-Prats, A., Puertes, C., Pulido-Velázquez, M., Sanchis-Ibor, C., Schirmer, M., Yang, H., and Jiménez-Martínez, J.: Modeling the effect of flood and drip irrigation on groundwater recharge, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-9514, https://doi.org/10.5194/egusphere-egu2020-9514, 2020.

EGU2020-9710 | Displays | HS2.2.1

Representing Small- Scale Storage Interventions Across the Cauvery Catchment Using a Macro- Scale Gridded Water Resource Model and Quantifying Their Effect on Catchment Hydrology.

Robyn Horan, Pawan Wable, Veena Srinivasan, Helen Baron, Virginie Keller, Gywn Rees, Helen Houghton- Carr, and Pradeep Mujumdar

Recently, there has been renewed interest in the utilisation of traditional small-scale storage interventions (check dams, field bunds and tanks) across India for the improvement of local water security. The Central Groundwater Board of India is encouraging the construction of interventions, such as check dams, field bunds and tanks, as the primary policy for the alleviation of water scarcity. It is of critical importance to understand the hydrological effect of these interventions at the small- and large-scale to maximise their impact and effectiveness. The quantification of small- scale interventions in hydrological modelling is often neglected, especially in large- scale modelling exercises. Although individually small, cumulatively these interventions may have a large effect on basin hydrology.  A bespoke version of the Global Water AVailability Assessment (GWAVA) model was developed to incorporate the impact of interventions on the hydrology. Interventions were conceptualised within the model structure using local knowledge, observed data and adaptations of existing reservoir representations. The effect of interventions on the water balance of the Cauvery Basin (81 000 km2), Peninsula India, and various small sub-catchments (each approximately 3500 km2) was studied. To quantify the impact of small interventions, two model runs were generated. An initial simulation was performed including a representation of the check dams, field bunds and tanks thought to be within the catchments, and compared with a “reference” simulation where no interventions were included but instead were replaced by grassland. The percentage difference for each component of the water balance was determined as an indicator of the impact of the interventions. The inclusion of interventions increases the total annual evaporation across the basin and reduces the annual streamflow. Although the interventions are constructed to provide increased surface and groundwater storage within the agricultural and urban areas, the implementation resulted in a significant decrease in total annual water storage within the sub- catchments. The aquifer levels rise minimally in the eastern sub-catchments and exhibit no change in the western sub- catchments. The aquifer levels in the mid- basin remained unchanged with the implantation of interventions.  Although the implementation of interventions are thought to increase the availability of groundwater at a local scale by upwards of two meters, the investigation using GWAVA suggest that aquifer levels are minimally affected. Based on the current understanding of interventions and the catchment hydrology, the wider effects of interventions on the water balance could be more detrimental to surface water security than anticipated and, thus, may not alleviate water poverty. The uncertainty related to the input data on interventions in the Cauvery may have affected the findings and thus further studies in regions with sufficient data availability and varying climate conditions may provide additional insight into the small- and large-scale effects of interventions.

How to cite: Horan, R., Wable, P., Srinivasan, V., Baron, H., Keller, V., Rees, G., Houghton- Carr, H., and Mujumdar, P.: Representing Small- Scale Storage Interventions Across the Cauvery Catchment Using a Macro- Scale Gridded Water Resource Model and Quantifying Their Effect on Catchment Hydrology., EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-9710, https://doi.org/10.5194/egusphere-egu2020-9710, 2020.

EGU2020-5807 | Displays | HS2.2.1

A new physically-based catchment modelling tool for reservoir re-engineering and renaturalisation

Daryl Hughes, Geoff Parkin, and Stephen Birkinshaw

The hydrological regimes of European catchments have been considerably modified by anthropogenic features such as dams, weirs and water abstractions, with nearly every major river fragmented. The negative impacts of such physical modifications on freshwater ecosystems are being increasingly recognised. Currently, European dam removal initiatives are being driven by factors such as the EU Habitats Directive, and the costs associated with maintaining redundant infrastructure. Climate change and the rewilding agenda may encourage further hydrological renaturalisation initiatives. In the English Lake District, several reservoirs are being actively considered for decommissioning within this decade. To understand how such catchments would respond to lake renaturalisation, robust catchment hydrology models are needed that can represent the effects of changes in physical infrastructure on the hydrological regime. However, many models tend to neglect such human impacts.

We present a new tool that incorporates reservoirs, including impounding structures, river regulations and abstractions. The method involved development of an enhanced version of the freely-available catchment modelling software, SHETRAN. A new ‘reservoir’ module was developed which includes the effects of hydraulic structures and sluice operations on lake stage and river flow. Results for the Crummock Water catchment and reservoir show that the reservoir model generates notably fitter simulations, particularly during dry periods where reservoir operations cause a distinct deviation from the regime expected in natural lake-river systems. Further simulations demonstrate quantitatively how lake renaturalisation might affect future hydrological regimes compared with the baseline scenario. Finally, we discuss the implications of this model for decision-making in the Crummock Water catchment, and the utility of the software for other anthropologically-modified catchments.

How to cite: Hughes, D., Parkin, G., and Birkinshaw, S.: A new physically-based catchment modelling tool for reservoir re-engineering and renaturalisation, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-5807, https://doi.org/10.5194/egusphere-egu2020-5807, 2020.

EGU2020-6541 | Displays | HS2.2.1

Hydrodynamic Simulation of Seasonal Fluvial Process over a Large Catchment

Xue Tong, Qiuhua Liang, and Gang Wang

Fluvial flooding induced by intense or prolonged rainfall poses a regular threat to people’s lives and properties in almost every part of the world. Modelling provides an essential tool for simulating and predicting the hydrological processes from rainfall-runoff to flooding driven by rainfall. Prediction of seasonal or longer-term fluvial processes over large catchments has traditionally been carried out using lumped/distributed hydrological models. However, these traditional hydrological models do not consider strict momentum conservation and they are not suited for accurate simulation of highly transient and dynamic rainfall-runoff and flooding process. On the other hand, sophisticated hydraulic/ hydrodynamic models have been widely used for modelling of flood inundation including those violent flash floods from intense rainfall. But due to their inhibitive computational cost and incapability in representing certain hydrological processes, no attempt has been reported to use a fully 2D hydrodynamic model to simulate long-term fluvial processes to provide more detailed information for the analysis of flood dynamics and subsequent impact on the environment.

Therefore, this work aims to further develop and test a hydrodynamic model to simulate seasonal fluvial processes in a large catchment. The proposed long-term fluvial processes modelling system is based on the High-Performance Integrated hydrodynamic Modelling System (HiPIMS). HiPIMS solves the full 2D nonlinear shallow water equations using a finite volume shock-capturing numerical method, which is further accelerated by modern GPUs for large-scale and long-term simulations. Surface storage, overland flow and flow dynamics are automatically captured by running simulations on high-resolution topographic data. New model components are developed and coupled to HiPIMS to account for infiltration and evaporation. For infiltration, the Green-Ampt method and curve number method are implemented and compared. The enhanced HiPIMS is applied to reproduce, at 20m resolution, the seasonal fluvial processes including flooding and recovery periods in the 2500km2 Eden Catchment, England for three months.

The simulation results are compared with gauge measurements of water level and discharge across the catchment to demonstrate the model’s capability in supporting long-term simulations. More simulations have been also carried out to investigate the model sensitivity to key model parameters, e.g. grid resolution, friction, infiltration and evaporation parameters.

 

How to cite: Tong, X., Liang, Q., and Wang, G.: Hydrodynamic Simulation of Seasonal Fluvial Process over a Large Catchment, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-6541, https://doi.org/10.5194/egusphere-egu2020-6541, 2020.

EGU2020-6788 | Displays | HS2.2.1

Coupling of the global hydrodynamic CaMa-Flood model with the ECMWF land surface model HTESSEL.

Emanuel Dutra, Dai Yamazaki, and Cinzia Mazzetti

Rivers are a key component of the land hydrological cycle and are crucial in many societal activities and natural hazards. Historically, hydrological modeling has not been tightly associated with numerical weather prediction (NWP) due to the different communities involved, requirements and underlying processes. The increased skill of NWP has led to the uptake of weather forecasts in hydrological models, in particular for flood forecasting. At the same time, developments of Earth System Models (ESM), mainly driven by the climate community have lead to a tight integration of the land hydrological cycle. River discharge is a key quality indicator of the integrated water budget, and its use as a forecast skill metric of NWP has a large potential. Freshwater input to the ocean is also important for the ocean circulation, which becomes increasingly relevant with the current atmosphere-ocean coupling in NWP. Considering all these points, the representation of rivers and floodplains dynamics and their associated impact on inland water evolution is of interest for a wide range of applications currently addressed by global NWP. 

In this study we present the key technical developments to achieve a 1-way and 2-way coupling between the global hydrodynamic CaMa-Flood model and the land surface component of the European Center for Medium-Range Weather Forecasts (ECMWF) HTESSEL. The models coupling followed a single executable strategy, i.e. avoiding external couplers. A coupling interface was developed for CaMa-Flood that is independent from the driving model, while keeping the stand-alone configuration. The coupling is flexible, allowing both models to run at different spatial resolutions. The implementation allows for a flexible integration of the models and independent development, and can be applied to other models.  

The current representation of inland water bodies in HTESSEL (lakes) was driven by their impact in NWP, but without the representation of rivers it was not possible to have a consistent water budget. The coupling of CaMa-Flood allows for an integrated earth system model approach. Several options for the 2-way interaction between CaMa-Flood flooded areas in HTESSEL inland water bodies were investigated. Despite the consistent results, several challenges are identified in the representation of inland water bodies, their variability and impact on water cycle.

How to cite: Dutra, E., Yamazaki, D., and Mazzetti, C.: Coupling of the global hydrodynamic CaMa-Flood model with the ECMWF land surface model HTESSEL., EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-6788, https://doi.org/10.5194/egusphere-egu2020-6788, 2020.

EGU2020-6789 | Displays | HS2.2.1

The case of distributed rainfall and spatially adaptive modeling

Ralf Loritz, Uwe Ehret, Malte Neuper, and Erwin Zehe

How important is information about distributed precipitation when we do rainfall-runoff modeling on the catchments scale?

The latter is surely one of the more frequently asked research questions in hydrological modeling. Most studies tackling the issue seem thereby to agree that distributed precipitation becomes more important if the ratio of catchment size against storm size decreases or if the spatial gradients of the rainfall field increase. Furthermore, is it often highlighted that catchments are surprisingly effective in smoothing out the spatial variability of the meteorological forcing, at least, if the focus is simulation integral fluxes and average states.

However, despite these agreements there is no straightforward guidance in the hydrological literature when these thresholds have been reached and when the spatial distribution of the precipitation starts dominating. This is because the answer to the above drawn question depends on the spatial variability of system characteristics, on the system state variables as well as on the strength of the rainfall forcing and its space-time variability. As all three controls vary greatly in space and time it is challenging to identify generally valid rules when information about the distribution of rainfall becomes important for predictive modelling.

The present study aims to overcome this limitation by developing a model framework to identify periods where the spatial gradients in rainfall intensity are larger than the ability of the landscape to internally dissipate those. This newly developed spatially adaptive modeling approach, uses the spatial information content of the precipitation to control the spatial distribution of our model. The main underlying idea of this approach is to use distributed models only when they are actually needed resulting in 1) a drastic decrease in computational times as well as 2) in a more appropriate representation of a hydrological system. Our results highlight that only during a few periods throughout a hydrological year do distributed precipitation data actually matter. However, they also show that these periods are often highly relevant with respect to certain extremes and that the successful simulation of these extremes require distributed information about the forcing and state of a given system.

How to cite: Loritz, R., Ehret, U., Neuper, M., and Zehe, E.: The case of distributed rainfall and spatially adaptive modeling, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-6789, https://doi.org/10.5194/egusphere-egu2020-6789, 2020.

EGU2020-5478 | Displays | HS2.2.1

Experimenting on simple and flexible top-down approaches for hydrological modelling

Sotirios Moustakas and Patrick Willems

Nowadays, a plethora of modelling software on rainfall-runoff and groundwater dynamics are available. Considering the complexity and heterogeneity of natural processes governing the water cycle, many of those models involve physically-based formulations. Inevitably, a large amount of data is also required. However, the available data are often insufficient, while their quality questionable. At the same time, an increasing model complexity also gives rise to high computational requirements. In order to mitigate some of the aforementioned issues, during the past years a simple and flexible top-down approach for distributed rainfall-runoff modelling has been developed (Tran et al., 2018). Essentially, the distributed rainfall-runoff model is built starting from a simple lumped model, whose parameters are then spatially disaggregated. Disaggregation is carried out using conceptual links between model parameters and natural catchment characteristics.

We now test an extended version of this methodology involving disaggregation relationships for more model parameters. Moreover, we evaluate modelling performance for 2 different configurations. The first starts from the parameters of a lumped conceptual model and is essentially the original approach. The second one starts from the parameters of a uniform distributed conceptual model. The motivation behind the new approach is that it allows a better-integrated routing scheme with less model parameters. In turn, this can further reduce equifinality (denoting the “phenomenon” that largely different parameter-sets can often result to largely similar model outcomes). The two approaches are inter-compared and evaluated against flow observations.

With the disaggregated models as basis, we also experiment on the potential of simple methods for modelling groundwater levels. We approach this challenge by trying to identify links between a) the variations and b) the reference levels of the modelled groundwater storages and observed groundwater levels. For example, we hypothesize that modelled storages can be scaled to the actual level variations via the specific yield, which expresses the amount of interconnected pores in the soil. The modelling methodology is evaluated against groundwater level measurements.

 

Tran, Q.Q., De Niel, J., Willems, P., 2018. Spatially Distributed Conceptual Hydrological Model Building: A Generic Top-Down Approach Starting From Lumped Models. Water Resour. Res. 54, 8064–8085.

How to cite: Moustakas, S. and Willems, P.: Experimenting on simple and flexible top-down approaches for hydrological modelling, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-5478, https://doi.org/10.5194/egusphere-egu2020-5478, 2020.

EGU2020-20280 | Displays | HS2.2.1

How to Tailor my Process-based Hydrological Model? Dynamic Identifiability Analysis of Flexible Model Structures

Axel Bronstert, Tobias Pilz, Till Francke, and Gabriele Baroni

In the field of hydrological modeling, many alternative mathematical representations of natural processes exist. To choose specific process formulations when building a hydrological model is therefore associated with a high degree of ambiguity and subjectivity. Identifiability analysis may provide guidance by constraining the a priori range of alternatives based on observations. In this work, a flexible simulation environment is used to build a process-based hydrological model with alternative process representations, numerical integration schemes, and model parametrizations in an integrated manner. The flexible simulation environment is coupled with an approach for dynamic identifiability analysis. The objective is to investigate the applicability of the coupled framework to identify the most adequate model structure. It turned out that identifiability of model structure varies in space and time, driven by the meteorological and hydrological characteristics of the study area. Moreover, the most accurate numerical solver is often not the best performing solution. This is possibly influenced by correlation and compensation effects among process representation, numerical solver, and parametrization. Overall, the proposed coupled framework proved to be applicable for the identification of adequate process-based model structures and is therefore a useful diagnostic tool for model building and hypotheses testing.

How to cite: Bronstert, A., Pilz, T., Francke, T., and Baroni, G.: How to Tailor my Process-based Hydrological Model? Dynamic Identifiability Analysis of Flexible Model Structures, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-20280, https://doi.org/10.5194/egusphere-egu2020-20280, 2020.

EGU2020-7884 | Displays | HS2.2.1 | Highlight

Towards global fully-distributed regionalization of hydrological model parameters

Hylke Beck, Ming Pan, Peirong Lin, Jan Seibert, Albert van Dijk, and Eric Wood

All hydrological models need to be calibrated to obtain satisfactory streamflow simulations. Here we present a novel parameter regionalization approach that involves the optimization of transfer equations linking model parameters to climate and landscape characteristics. The optimization was performed in a fully spatially distributed fashion at high resolution (0.05°), instead of at lumped catchment scale, using an unprecedented database of daily observed streamflow from 4229 headwater catchments (<5000 km2) worldwide. The optimized equations were subsequently applied globally to produce parameter maps for the entire land surface including ungauged regions. The approach was implemented using a bounded version of the Kling-Gupta Efficiency metric (KGEB) and a gridded version of the HBV hydrological model. Ten-fold cross-validation was used to evaluate the generalizability of the approach and to obtain an ensemble of parameter maps. For the 4229 independent validation catchments, the regionalized parameters yielded a median daily KGEB of 0.30 (equivalent to a conventional KGE of 0.46). The median KGEB improvement (relative to uncalibrated parameters) was 0.21, with improvements obtained for 88 % of the independent validation catchments. These scores compare favourably to those from previous large catchment sample studies. The degree of performance improvement due to the regionalized parameters did not depend on climate or topography. Substantial improvements were obtained even for independent validation catchments located far from the catchments used for optimization, underscoring the value of the derived parameters for poorly gauged regions. The regionalized parameters — available via www.gloh2o.org/hbv — should be useful for numerous hydrological applications requiring accurate streamflow simulations.

How to cite: Beck, H., Pan, M., Lin, P., Seibert, J., van Dijk, A., and Wood, E.: Towards global fully-distributed regionalization of hydrological model parameters, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-7884, https://doi.org/10.5194/egusphere-egu2020-7884, 2020.

EGU2020-10141 | Displays | HS2.2.1

Automatic estimation of parameter transfer functions for distributed hydrological models - a case study with the mHM model

Moritz Feigl, Stephan Thober, Mathew Herrnegger, Luis Samaniego, and Karsten Schulz

The estimation of parameters for spatially distributed rainfall runoff models is a long-studied, complex and ill-posed problem. Relating parameters of distributed hydrological models to geophysical properties of catchments could potentially solve some of the major difficulties connected to it.

One way to define this relationship is by the use of explicit equations called parameter transfer functions, which relate geophysical catchment properties to the model parameters. Computing parameter fields using transfer functions would result in spatially consistent parameter fields and the potential to extrapolate to other catchments. A further advantage is that the dimensionality of the parameter space is reduced because the transfer function parameters are applied to all computational units (i.e., grid cells). However, the structure and parameterization of transfer functions is often only implicitly assumed or needs to be derived by a laborious literature guided trial and error process.

For this reason we use Function Space Optimization (FSO), a symbolic regression approach which automatically estimates the structure and parameterization of transfer functions from catchment data. FSO transfers the search of the optimal function to a searchable continuous vector space. To create this space, a text generating neural network with a variational autoencoder (VAE) architecture is used. It is trained to map possible transfer functions and their distributions to a 6-dimensional space. After training, a continuous optimization is applied to search for the optimal transfer function in this function space. FSO was already tested in a virtual experiment using a parsimonious hydrological model, where its ability to solve the problem of transfer function estimation was shown.

Here, we further test FSO by applying it in a real world setting to the mesoscale hydrological model (mHM). mHM is a widely applied distributed hydological model, which uses transfer functions for all its parameters. For this study, we estimate transfer functions for the parameters porosity and field capacity, which both influence a range of hydrologic processes, e.g. infiltration and evapotranspiration. We compare the FSO estimated transfer functions with the already existing mHM transfer functions and examine their influence on the model performance.

In summary, we show the general applicability of FSO for distributed hydrological models and the advantages and capabilities of automatically defining parameter transfer functions.

How to cite: Feigl, M., Thober, S., Herrnegger, M., Samaniego, L., and Schulz, K.: Automatic estimation of parameter transfer functions for distributed hydrological models - a case study with the mHM model, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-10141, https://doi.org/10.5194/egusphere-egu2020-10141, 2020.

EGU2020-4184 | Displays | HS2.2.1

Process-based model evaluation of cold region hydrological processes

Wouter Knoben, Abbas Fayad, Vincent Vionnet, and Martyn Clark

Model simulations of hydrological processes are critical for applications in streamflow forecasting and water security assessments. In this work, we develop a model-agnostic benchmarking framework to evaluate the fidelity of continental-domain model simulations. The benchmarking framework includes (1) synthetic test cases to evaluate the implementation of the model equations; (2) process-based diagnostics in research basins to evaluate model representations of individual processes; and (3) continental-domain benchmarks to evaluate the fidelity of large-domain model simulations. As a test case, we use simulations from the Structure for Unifying Multiple Modeling Alternatives (SUMMA) configured across the North America domain. We rely on existing theory about cold-region hydrologic processes and large-domain observations of these processes to define process-specific evaluation metrics. These process diagnostics provide insights in our current ability to model cold region hydrological processes across the North America domain.

How to cite: Knoben, W., Fayad, A., Vionnet, V., and Clark, M.: Process-based model evaluation of cold region hydrological processes, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-4184, https://doi.org/10.5194/egusphere-egu2020-4184, 2020.

EGU2020-11390 | Displays | HS2.2.1

Modeling lowland catchment hydrology: A comparison of model versions

Paul D. Wagner, Katrin Bieger, Jeffrey G. Arnold, and Nicola Fohrer

The hydrology of rural lowland catchments in Northern Germany is characterized by near-surface groundwater tables and extensive tile drainage. Previous research has shown that representing these characteristics with the hydrologic model SWAT (Soil and Water Assessment Tool) required an improvement of groundwater processes, which has been achieved by dividing the shallow aquifer into a fast and a slow shallow aquifer. The latest version of the Soil and Water Assessment Tool (SWAT+) features several improvements compared to previous versions of the model, e.g. the definition of landscape units that allow for a better representation of spatio-temporal dynamics. To evaluate the new model capabilities for lowland catchments, we assess the performance of SWAT+ in comparison to previous SWAT applications in the Kielstau Catchment in Northern Germany. The Kielstau Catchment is about 50 km² large, is dominated by agricultural land use, and has been thoroughly monitored since 2005. In particular, we explore the capabilities of SWAT+ in terms of watershed configuration and simulation of landscape processes by comparing two model setups. The first setup is comparable to previous SWAT models for the catchment, i.e. yields from hydrologic response units are summed up at subbasin level and added directly to the stream. In the second SWAT+ model, subbasins are divided into upland areas and floodplains and runoff is routed across the landscape before it reaches the streams. Model performance is assessed with regard to measured stream flow at the outlet of the catchment. Results from the new SWAT+ model confirm that two groundwater layers are necessary to represent stream flow in the catchment. The representation of routing processes from uplands to floodplains in the model further improved the simulation of stream flow. The outcomes of this study are expected to contribute to a better understanding and model representation of lowland hydrology.

How to cite: Wagner, P. D., Bieger, K., Arnold, J. G., and Fohrer, N.: Modeling lowland catchment hydrology: A comparison of model versions, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-11390, https://doi.org/10.5194/egusphere-egu2020-11390, 2020.

EGU2020-8079 | Displays | HS2.2.1

The role of precipitation in hydrological model uncertainty

András Bárdossy, Chris Kilsby, Faizan Anwar, and Ning Wang

Rainfall-runoff models produce outputs which differ from observations due to uncertainties in process description, process parametrization, uncertainties in observations and changing spatio-temporal variability of input and state variables. Traditionally, attention has been focused mostly on process parameters to quantify runoff uncertainty using e.g. GLUE.

Here we have focused on the role of precipitation uncertainty relating to discharge. For this purpose, we used an inverse model approach. We generated time series of daily precipitation with high spatial resolution  using a modified version of Random Mixing and the Shannon-Whittaker interpolation to improve simulated runoff using the SHETRAN (physically-based) and HBV (conceptual) models, both spatially distributed for various sub-catchments of the Neckar River in Germany.  HBV was initially calibrated using interpolated precipitation, while SHETRAN uses pre-defined parameters. The modelling goal was to find a spatio-temporal series of precipitation which improved the predicted runoff,  under the constraints that the precipitation values be the same at the measurement locations and share their spatial variability with the observations at a given step. Care was taken to select subsequent days for improvement such that the previously improved step considered the effect of the previous steps.

We asked the questions: i) does improving precipitation inputs for one sub-catchment bring runoff improvement for the others? ii) Can the improved precipitation using SHETRAN be used for HBV and still get runoff improvements as compared to the interpolated precipitation and vice versa?

Results showed that overall runoff errors were reduced by 40 to 50% for all sub-catchments. For the peaks, a reduction of 70 to 90% was observed. As compared with the interpolated fields, new fields showed similar overall distribution but different details at finer spatial scales. Swapping improved precipitations between SHETRAN and HBV showed improvement as compared with the discharge from interpolated precipitation.

How to cite: Bárdossy, A., Kilsby, C., Anwar, F., and Wang, N.: The role of precipitation in hydrological model uncertainty, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-8079, https://doi.org/10.5194/egusphere-egu2020-8079, 2020.

EGU2020-6103 | Displays | HS2.2.1

The sensitivity of hydrologic processes across North America considering model structure and parametric uncertainty

Juliane Mai, James Craig, Bryan Tolson, and Richard Arsenault

Information on the sensitivity of model parameters and model components such as processes are essential for model development, model improvement, and model calibration, amongst others.

In this work we apply the method of the extended Sobol’ Sensitivity analysis (xSSA) which not only considers parametric uncertainty but also fully incorporates structural uncertainties (Mai et al. (2019) WRR; under review). The results of such an analysis yield not only the traditional parameter sensitivities but also sensitivities of model process options (e.g., different snowmelt algorithms) and sensitivities of model processes (e.g., snowmelt, infiltration, baseflow). 

The Raven hydrologic modelling framework (http://raven.uwaterloo.ca) allowing for flexible model structures is employed in this work. We used three options each for infiltration, quickflow, and snow melt as well as two options each for baseflow, and soil evaporation. Rather than considering 108 (3x3x3x2x2) discrete model setups, we used weighted sums of all process options yielding an infinite number of models tested.

The analysis is performed for 5797 basins across Canada (CANOPEX; Tarek et al. (2019) HESSD) and the US (USGS). The lumped basin setups use daily precipitation and  minimum/ maximum daily temperature. The sensitivity analysis is based on 20 years of daily streamflow simulations (1991-2010) after two years of spin-up (1989-1990). No observed streamflow is required for the analysis.

In total more than 450 million model runs were performed to determine sensitivities of parameters, process options and processes (51%, 35%, and 14% of model runs, respectively) across the almost 5800 basins. The computational demand was about 12 core years producing 23 TB of raw model outputs.

The analysis allows for unique, new insights into the importance of hydrologic processes and parameters (practically) independent of the model (structure) used. A few highlight results are: 1) Baseflow and other sub-surface processes are of low importance across North America- especially when time points of high flows are of interest. 2) Percolation, evaporation, and infiltration show very similar patterns with increased importance in South-eastern US and west of the Rocky Mountains. 3) Up to 30% of the overall model variability can be attributed to snow melt in regions that are snow dominated (Northern Canada and Rocky mountains). Potential melt shows a similar gradient as snow melt with sensitivities of above 60% in the Province of Quebec and the Rocky Mountains. 4) Direct runoff (quickflow) is the most sensitive of all hydrologic processes- especially in South-Eastern US it is responsible for more than 80% of the model variability.

How to cite: Mai, J., Craig, J., Tolson, B., and Arsenault, R.: The sensitivity of hydrologic processes across North America considering model structure and parametric uncertainty, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-6103, https://doi.org/10.5194/egusphere-egu2020-6103, 2020.

EGU2020-18880 | Displays | HS2.2.1

Multi-objective calibration of a distributed eco-hydrological model using several remotely sensed information

Félix Francés, Carlos Echeverría, Maria Gonzalez-Sanchis, and Fernando Rivas

Calibration of eco-hydrological models is difficult to carry on, even more if observed data sets are scarce. It is known that calibration using traditional trial-and-error approach depends strongly of the knowledge and the subjectivity of the hydrologist, and automatic calibration has a strong dependency of the objective-function and the initial values established to initialize the process.

The traditional calibration approach mainly focuses on the temporal variation of the discharge at the catchment outlet point, representing an integrated catchment response and provides thus only limited insight on the lumped behaviour of the catchment. It has been long demonstrated the limited capabilities of such an approach when models are validated at interior points of a river basin. The development of distributed eco-hydrological models and the burst of spatio-temporal data provided by remote sensing appear as key alternative to overcome those limitations. Indeed, remote sensing imagery provides not only temporal information but also valuable information on spatial patterns, which can facilitate a spatial-pattern-oriented model calibration.

However, there is still a lack of how to effectively handle spatio-temporal data when included in model calibration and how to evaluate the accuracy of the simulated spatial patterns. Moreover, it is still unclear whether including spatio-temporal data improves model performance in face to an unavoidable more complex and time-demanding calibration procedure. To elucidate in this sense, we performed three different multiobjective calibration configurations: (1) including only temporal information of discharges at the catchment outlet (2) including both temporal and spatio-temporal information and (3) only including spatio-temporal information. In the three approaches, we calibrated the same distributed eco-hydrological model (TETIS) in the same study area: Carraixet Basin, and used the same multi-objective algorithm: MOSCEM-UA. The spatio-temporal information obtained from satellite has been the surface soil moisture (from SMOS-BEC) and the leaf area index (from MODIS).

Even though the performance of the first calibration approach (only temporal information included) was slightly better than the others, all calibration approaches provided satisfactory and similar results within the calibration period. To put these results into test, we also validated the model performance by using historical data that was not used to calibrate the model (validation period). Within the validation period, the second calibration approach obtained better performance than the others, pointing out the higher reliability of the obtained parameter values when including spatio-temporal data (in this case, in combination with temporal data) in the model calibration. It is also reliable to mention that the approaches considering only spatio-temporal information provided interesting results in terms of discharges, considering that this variable was not used at all for calibration purposes.

How to cite: Francés, F., Echeverría, C., Gonzalez-Sanchis, M., and Rivas, F.: Multi-objective calibration of a distributed eco-hydrological model using several remotely sensed information, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-18880, https://doi.org/10.5194/egusphere-egu2020-18880, 2020.

EGU2020-205 | Displays | HS2.2.1

Model adequacy tests for improving predictions in ungauged basins

Cristina Prieto, Nataliya Le Vine, Dmitri Kavetski, César Álvarez, and Raúl Medina

Flow prediction in ungauged catchments is a major unresolved challenge in scientific and engineering hydrology. Meeting this challenge is made difficult by the uncertainty in the “regionalization” model used to transpose hydrological data (e.g., flow indices) from gauged to ungauged basins, and by the uncertainty in the hydrological model used to predict streamflow in the ungauged basin. This study combines recent advances in flow index selection, regionalization via machine learning methods, and a Bayesian inference framework. In addition, it proposes two new statistical metrics, “DistanceTest” and “InfoTest”, to assess the adequacy of a model before estimating its parameters. “DistanceTest” quantifies whether a model (hydrological or regionalization) is likely to reproduce the available hydrological information in a catchment. “InfoTest” is based on Bayes Factors and quantifies the information added by a model (hydrological or regionalization) over prior knowledge about the available hydrological information in a catchment). The proposed adequacy tests can be seen as a prerequisite for a model (hydrological or regionalization) being considered capable of providing meaningful and high quality flow time series predictions in ungauged catchments. If a model is found inadequate a priori and rejected, the modeler is spared the effort in estimating the model parameters, which can be a substantial saving.

The proposed regionalization approach is applied to 92 northern Spain catchments, with 16 catchments treated as ungauged. It is found that (1) a small number of PCs capture approximately 87% of variability in the flow indices, and (2) adequacy tests with respect to regionalized information are indicative of (but do not guarantee) the ability of a hydrological model to predict flow time series. The adequacy tests identify the regionalization of flow index PCs as adequate in 12 of 16 catchments but the hydrological model as adequate in only 1 of 16 catchments. In addition, the case study results suggest that the hydrological model is the main source of uncertainty in comparison to the regionalization model, and hence should receive the main priority in subsequent work at the case study catchments.

How to cite: Prieto, C., Le Vine, N., Kavetski, D., Álvarez, C., and Medina, R.: Model adequacy tests for improving predictions in ungauged basins, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-205, https://doi.org/10.5194/egusphere-egu2020-205, 2020.

EGU2020-7825 | Displays | HS2.2.1

Behind the scenes of runoff performance

Tanja de Boer-Euser, Laurène Bouaziz, Guillaume Thirel, Lieke Melsen, Joost Buitink, Claudia Brauer, Jan de Niel, Sotirios Moustakas, Patrick Willems, Benjamin Grelier, Gilles Drogues, Fabrizio Fenicia, Jiri Nossent, Fernando Pereira, Hubert Savenije, Albrecht Weerts, and Markus Hrachowitz

Hydrological models are valuable tools for short-term forecasting of river flows, long-term predictions for water resources management and to increase our understanding of the complex interactions of water storage and release processes at the catchment scale. Hydrological models provide relatively robust estimates of streamflow dynamics, as shown by the countless applications in many regions across the world. However, various model structures can lead to similar aggregated outputs, i.e. model equifinality. To provide reliable estimates, it is of critical importance that not only the aggregated response but also the internal behaviors are consistent with their real-world equivalents. In a previous international comparison study (de Boer-Euser et al., 2017), eight research groups followed the same protocol to calibrate their twelve models on streamflow for several catchments within the Meuse basin. In the current study, we hypothesize that these twelve process-based models with similar runoff performance have similar representations of internal states and fluxes. We test our hypothesis by comparing internal states and fluxes between models and we assess their plausibility using remotely-sensed products of actual evaporation, snow cover, soil moisture and total storage anomalies. Our results indicate that models with similar runoff performance represent internal states and fluxes differently. The dissimilarities in internal process representation imply that these models cannot all simultaneously be close to reality. Using remotely-sensed products, the plausibility of process representation could only be evaluated to some extent as many variables remain unknown, highlighting the need for more experimental research. The study further emphasizes the value of multi-model, multi-parameter studies to reveal to decision-makers the uncertainty inherent to the lack of evaluation data and the heterogeneous hydrological landscape.

References:
de Boer-Euser, T., Bouaziz, L., De Niel, J., Brauer, C., Dewals, B., Drogue, G., Fenicia, F., Grelier, B., Nossent, J., Pereira, F., Savenije, H., Thirel, G., and Willems, P.: Looking beyond general metrics for model comparison – lessons from an international model intercomparison study, Hydrol. Earth Syst. Sci., 21, 423–440, https://doi.org/10.5194/hess-21-423-2017, 2017.

How to cite: de Boer-Euser, T., Bouaziz, L., Thirel, G., Melsen, L., Buitink, J., Brauer, C., de Niel, J., Moustakas, S., Willems, P., Grelier, B., Drogues, G., Fenicia, F., Nossent, J., Pereira, F., Savenije, H., Weerts, A., and Hrachowitz, M.: Behind the scenes of runoff performance, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-7825, https://doi.org/10.5194/egusphere-egu2020-7825, 2020.

EGU2020-487 | Displays | HS2.2.1

Investigating the reasons for poor model performance in a changing climate

Doris Duethmann, Günter Blöschl, and Juraj Parajka

Hydrological models are often applied to estimate climate change impacts on hydrology. However, several studies demonstrated that hydrological models do not perform well when applied under changing climate conditions. In order to decide on the way forward for improving hydrological modelling in climate change contexts, it is important to understand the reasons for poor performance in a changing climate, but there are only a few studies on this topic.

Here we revisit a study in Austria that demonstrated the inability of a conceptual model to simulate the discharge response to increases in precipitation and air temperature. We set up hypotheses for the differences between the observed and simulated changes in discharge and test these using simulations with various modifications of the model (including modifications of the input data, model calibration, and model structure).

The baseline model overestimates discharge trends over 1978−2013, on average over all 156 catchments, by 93 ± 50 mm yr−1 per 35 years. Accounting for vegetation dynamics in the calculation of reference evaporation based on a satellite-derived vegetation index, reduces the difference between simulated and observed discharge by 35 ± 9 mm yr−1 per 35 years. Inhomogeneities in the precipitation data, caused by a variable number of stations and, to a lesser degree, climate variability effects on the undercatch error, can explain 44 ± 28 mm yr−1 per 35 years of this difference. Extending the calibration period from 5 to 25 years, varying the objective function by including annually aggregated discharge data, or estimating evaporation with the Penman-Monteith instead of the Blaney-Criddle approach has little influence on the simulated discharge trends. The model structure problem with respect to vegetation dynamics has important implications for studies in a climate change context. Our results furthermore highlight the importance of using precipitation data based on a stationary input station network for studying observed hydrologic changes.

How to cite: Duethmann, D., Blöschl, G., and Parajka, J.: Investigating the reasons for poor model performance in a changing climate, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-487, https://doi.org/10.5194/egusphere-egu2020-487, 2020.

EGU2020-4850 | Displays | HS2.2.1

Systemic Change in Hydrology: Spatio-temporal parameter variability of the PCR-GLOBWB hydrological model in the Rhine-Meuse basin

Jessica Ruijsch, Edwin Sutanudjaja, Judith Verstegen, and Derek Karssenberg

Nowadays, a large part of hydrological research is focussed on hydrological modelling, both to improve system understanding and to simulate future systems to support decision making. Although the necessary simplifications in hydrological models such as empirical formulas or spatial and temporal discretisation can result in deviations in model predictions, hydrological models often perform well due to model calibration.  However, fundamental changes in system behaviour can occur that are not represented by the used model structure. These changes can therefore not be simulated and can result in deviating model results.  We refer to this situation as ‘systemic change’. To detect systemic change, one can calibrate the model separately for different time periods, and evaluate whether thus-found parameter values change over time, which is an indication of systemic change (Verstegen et al., 2016). The aim of this study is to use this approach to detect possible systemic changes in the Rhine-Meuse basin when modelled with the PCR-GLOBWB hydrological model.

PCR-GLOBWB is run for Rhine-Meuse basin for 1901-2010 at a daily time step with a 30 arcminute resolution, after which a brute force calibration is performed for five parameters (degree day factor, Manning’s roughness coefficient, soil thickness, saturated hydraulic conductivity and groundwater coefficient) using measured discharge data from the Global Runoff Data Centre (GRDC) at four locations in the catchment. To be able to identify the time stability of these parameters, the model is not only calibrated for the entire 1901-2010 period, but also for 10-year rolling calibration periods (i.e. 1901-1911, 1902-1912, 1903-1913, etc.). This results in a time series with 100 parameter values for each parameter, which is analysed for potential trends at the different calibration locations. First results indicate a decrease in the optimal parameter values for soil thickness and saturated hydraulic conductivity and an increase in the optimal parameter values for degree day factor and Manning’s roughness coefficient through time, especially in the upstream areas such as Basel. If the calibration is performed more downstream, for example at Lobith, the optimal parameter values are less variable through time.

These results are used to determine the effect of potential systemic changes on the uncertainty of hydrological predictions by making three forecasts; one with stable parameter values and a stationary climate, one with time-variant parameter values and one with a future climate scenario. The last forecast enables comparing the magnitude of change caused by the potential time-variant parameters with the change caused by time-variant climatic forcing. This way, the study gives more insight in both the occurrence of systemic change and its potential consequences, which can contribute to a better understanding of the behaviour of hydrological models under changing conditions.

Reference

Verstegen, J. A., Karssenberg, D., van der Hilst, F., & Faaij, A. P. C. (2016). Detecting systemic change in a land use system by Bayesian data assimilation. Environmental Modelling & Software, 75, 424–438. https://doi.org/10.1016/j.envsoft.2015.02.013

How to cite: Ruijsch, J., Sutanudjaja, E., Verstegen, J., and Karssenberg, D.: Systemic Change in Hydrology: Spatio-temporal parameter variability of the PCR-GLOBWB hydrological model in the Rhine-Meuse basin, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-4850, https://doi.org/10.5194/egusphere-egu2020-4850, 2020.

EGU2020-7147 | Displays | HS2.2.1

The additional value of using proxy data besides runoff for calibrating a conceptual hydrological model in a small agricultural catchment

Borbála Széles, Juraj Parajka, Patrick Hogan, Rasmiaditya Silasari, Lovrenc Pavlin, Peter Strauss, and Günter Blöschl

The aim of this study was to explore the additional value of using proxy data besides runoff for calibrating a conceptual hydrological model. The study area was the Hydrological Open Air Laboratory (HOAL), a 66 ha large experimental catchment in Austria. A conceptual, HBV type, spatially lumped hydrological model was calibrated following two approaches. First, the model was calibrated in one step using only runoff data. Second, we proposed a step-by-step approach, where the modules of the model (snow, soil moisture and runoff generation) were calibrated using proxy data besides runoff, such as snow, actual evapotranspiration, soil moisture, overland flow and groundwater level. The two approaches were evaluated on annual, seasonal and daily time scales. Using the proposed step-by-step approach, the runoff volume errors in the calibration and validation periods were 0% and -1%, the monthly Pearson correlation coefficients were 0.92 and 0.82, and the daily logarithmic Nash Sutcliffe efficiencies were 0.59 and 0.18, respectively. The additional benefit of using proxy data besides runoff was the improved overall process consistency compared to the approach when only runoff was used for model calibration. Soil moisture and evapotranspiration observations had the largest influence on simulated runoff, while the calibration of the snow and runoff generation modules had a smaller influence.

How to cite: Széles, B., Parajka, J., Hogan, P., Silasari, R., Pavlin, L., Strauss, P., and Blöschl, G.: The additional value of using proxy data besides runoff for calibrating a conceptual hydrological model in a small agricultural catchment, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-7147, https://doi.org/10.5194/egusphere-egu2020-7147, 2020.

EGU2020-347 | Displays | HS2.2.1

Investigating spatio-temporal variability of soil moisture in a small farmland: from point to catchment scale

Tailin Li, Nina Noreika, Jakub Jeřábek, Josef Krasa, David Zumr, and Tomáš Dostál

Many studies in recent years have focused on spatio-temporal variability of soil moisture and its value in hydrology and agriculture. The highly dynamic of soil moisture is controlled by soil properties, topography, landuse, climate conditions, and anthropogenic impacts. However, the understanding of soil moisture dynamics is limited by measurement restrictions. The aim of this study is to analyse spatio-temporal patterns of soil moisture using various soil moisture monitoring techniques and numerical modelling approaches that have been developed for application at differing scales at the Nucice experimental catchment (0.53 km2), which is located just outside of Prague, the Czech Republic.

The experimental catchment is dominated by agricultural activities. To identify spatio-temporal patterns in the catchment, we have implemented shallow soil moisture measurements at point-scale, hillslope-scale, and catchment-scale. We have deployed FDR (frequency domain reflectometry) sensors at different depths for point-scale measurements. The monitoring of hillslope-scale and catchment-scale have been mostly accomplished by field surveys with HydroSense II sensors. Subsequently, we have applied geostatistical analyses (Kriging and inverse distance weighting interpolation) for the measured soil moisture data to discover spatial patterns in soil moisture across the catchment. Besides, numerical models Hydrus (1D and 2D), MIKE-SHE, and SWAT have been set up at this study site. These models have been calibrated with event-based data and soil moisture measurements, which present a better image of the hydrological processes and spatio-temporal dynamics of soil moisture at various scales. The modelling outcomes have not only fit agreeably with the observed discharge and the temporal dynamics of soil moisture but have also identified wet zones along hillslopes.

Further research will intensify the soil moisture monitoring at the catchment-scale by using remote sensing and Comsic-ray soil moisture probes. Also, anthropogenic impacts (e.g. influence of wheel track) should be considered in the modelling approach. Ultimately, we should be able to understand and predict the spatio-temporal dynamics of soil moisture in small scale agricultural catchments under different climate conditions.

This research has been supported by project H2020 No. 773903 SHui, focused on water scarcity in European and Chinese cropping systems.

How to cite: Li, T., Noreika, N., Jeřábek, J., Krasa, J., Zumr, D., and Dostál, T.: Investigating spatio-temporal variability of soil moisture in a small farmland: from point to catchment scale, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-347, https://doi.org/10.5194/egusphere-egu2020-347, 2020.

EGU2020-20476 | Displays | HS2.2.1

SURFLAT: Measuring and modelling surface runoff in flat landscapes

Peter Schaap, Perry de Louw, and Sjoerd van der Zee

Surface runoff is widely recognized as playing an important and unique role in contaminant
transport from agricultural fields to the river system. Its quantification however is still
underdeveloped, especially in flat areas. Because micro-topography (< 10 cm) likely is an
important controlling factor in such landscapes, accurate predictions of the occurrence and
quantity of surface runoff are limited by a lack of high-quality data and/or computational power.
This project will explore the applicability of both conceptual (fill-and-spill) and state-of-the-art
physically based models to estimate surface runoff at the field scale. Laser technology will provide
high resolution surface topography data and direct measurements of surface runoff will aid in
validating the hydrologic models. The goal of this research is to use the results of the field study to
develop an efficient and accurate upscaling scheme, centred around a generic parameterization of
micro-topographic variability. This could support decision and policy making and contribute to
increasing the water quality of river systems.

How to cite: Schaap, P., de Louw, P., and van der Zee, S.: SURFLAT: Measuring and modelling surface runoff in flat landscapes, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-20476, https://doi.org/10.5194/egusphere-egu2020-20476, 2020.

Traditionally, rainfall runoff models are calibrated on discharge observed at the basin outlet. This may result in accurate flow predictions, but not necessarily correctly represent internal processes in space and time; especially in poorly gauged regions where limited ground observations are available. More and more satellite observations become available which can be valuable for model development and calibration to improve the representation of internal processes in space and time. In this study, satellite based evaporation and total water storage observations were used to improve, in a stepwise analysis, the structure of a hydrological model and the selection of feasible parameter sets. For this purpose, a semi-distributed rainfall runoff model, accounting for sub-grid process heterogeneity, was developed for the poorly-gauged Luangwa River basin in Zambia. As benchmark, this model was calibrated with respect to observed discharge. Then, the model was modified by (1) including upwelling groundwater in low-elevation parts of the landscape close to the river, depending on the water availability in the (un-) saturated zone and (2) adjusting the spatial representation of the groundwater. Next, each model was calibrated to all variables simultaneously with respect to discharge, evaporation and total water storage. In the benchmark case, calibrated on discharge only, the model reproduced the discharge well, but failed to provide an adequate spatiotemporal representation of evaporation and total water storage, especially in wetland dominated areas. Overall model performance improved most when including upwelling groundwater as a function of the saturated zone and when calibrating on all variables (discharge, evaporation and total storage) simultaneously. Hence including satellite based data on evaporation and total water storage improved model structure development and identifying feasible parameter sets.

How to cite: Hulsman, P., Savenije, H., and Hrachowitz, M.: Stepwise improvement of hydrological model concepts using satellite based evaporation and total water storage estimations, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-9094, https://doi.org/10.5194/egusphere-egu2020-9094, 2020.

It is important yet challenging to predict runoff in data sparse regions or ungauged regions, majority of which belong to headwater catchments that are normally the major water source for middle and lower river reaches. There are numerous studies carried out since the launch of the Predictions in Ungauged Basins (PUB) initiative by the International Association of Hydrological Sciences (IAHS) in 2003. Most runoff prediction studies rely on modelling approaches via two steps. The first step is to calibrate the hydrological model against observed streamflow at the gauged catchments. The second step is regionalization in which the set of calibrated parameter values from a suitable donor catchment is used for predicting runoff in a targeted ungauged catchment. The major challenge of this approach is that when the gauged catchments are sparsely distributed or little available, it is hard to get sensible regionalization results. This study develops a new approach to calibrate a hydrological model purely against remote sensed actual evapotranspiration data obtained from 8-day and 500 m resolution PML-V2 products and the calibrated parameters can be directly used for runoff prediction across global land surface. This approach has been successfully used for predicting daily, monthly and annual runoff in Australia and southeastern Tibetan Plateau. This is an exciting research domain for hydrologists to pursue since remote sensing data is accumulated in a fast-increasing rate, and will provide researchers an unprecedent opportunity.

How to cite: Zhang, Y.: Using remote sensing evapotranspiration solely calibrating hydrology model for predicting runoff time series in ungauged regions , EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-12227, https://doi.org/10.5194/egusphere-egu2020-12227, 2020.

Drought is a reoccurring worldwide natural hazard that affects not only food production but also economics, health, and infrastructure. It is also known that regional drought condition is sensitive to the fine particulate matters (PM) and has relationships with future changes in fine dust levels and associated health impacts under climate change. This mode is strongly correlated to evapotranspiration and land surface conditions and drought index might be good when the actual evapotranspiration and the land surface characteristics are implicitly included in the formula. The procedure for estimating actual evapotranspiration is complex and scientists often tend to select simple model that does not require intensive field data. As a preliminary study this study checks the possibility of PT-JPL which is relatively simple and requires minimum number of observations for estimating local actual evapotranspiration. The model has no calibration, tuning, or spin-up for local adjustment. The model was set up for five representative stations in East Asia. The satellite-collected normalized difference vegetation index (NDVI) and soil-adjusted vegetation index (SAVI) were used to describe the land surface characteristics. Meteorological information such as temperature, water vapor, radiation, and actual evapotranspiration was retrieved from AsiaFlux. The results show that the PT-JPL is promising for estimating local actual evapotranspiration. This study will extend to developing a drought index and its relationship to particulate matters (PM) in the near future.

 

Key words: Actual evapotranspiration, Particulate matters (PM), Drought, PT-JPL

 

Acknowledgement

This work was supported by the National Research Foundation of Korea (NRF-2017-2017001809)

How to cite: Lee, K.-H.: Checking actual evapotranspiration model using remotely collected surface data: Case study, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-20939, https://doi.org/10.5194/egusphere-egu2020-20939, 2020.

In this study, the Hargreaves monthly correction factor is presented to estimate the reference evapotranspiration. For the analysis, I used daily weather data from 1989 to 2018, at 67 meteorological stations located throughout the Korean peninsula.

A large number of more or less empirical methods have been developed over the last 50 years by numerous scientists and specialists worldwide to estimate evapotranspiration from different climatic variables. The FAO Penman-Monteith method is recommended as the sole ETo method for determining reference evapotranspiration. However, the Penman-Monteith method has the disadvantage of inputting a lot of weather data. In addition, there is a lack of meteorological data when using old historical data or as a test bed for developing countries.

In the case of the Hargreaves method, the reference evapotranspiration can be estimated only if the latitude, maximum and minimum temperatures of the meteorological station are known. However, the accuracy of the results is not as good as that of the Penman-monteith method. Thus, using the genetic algorithm method suggested the monthly correction factor of the Hargreaves method each station. The reference evapotranspiration amount calculated by Penman-Monteith was set as the true value, and the learning period of genetic algorithm was set from 1989 to 2013, and the validation period was set from 2014 to 2018.

In order to verify the model efficiency, the root mean square error decreased and the correlation coefficient increased when the monthly correction coefficient was applied to the reference evapotranspiration calculated by the Hargreaves method.

It is very important to estimate the reference evapotranspiration amount in order to develop the water long-term plan.

With the development of measuring equipment and technological capabilities, it is now possible to simulate the state of nature as if it were real, but many problems arise when using historical data or analyzing developing countries.

If the monthly correction coefficient suggested in this study is applied, it is possible to estimate the standard evaporation amount with a more approximate value.

 

Acknowledgements

 This research is supported by the Research Program (20200041-001) of Korea Institute of Civil Engineering & Building Technology 

How to cite: Kim, D.: Estimation of Evapotranspiration using the Modified Hargreaves Equation by Genetic Algorithm, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-8421, https://doi.org/10.5194/egusphere-egu2020-8421, 2020.

Hydrological modeling in arid basins located in developing countries often lacks sufficient hydrological data because, e.g., rain gauges are typically absent at high elevations and inflow to ungauged areas around large closed lakes such as Lake Urmia is difficult to estimate. We tried to improve precipitation and runoff estimation in Lake Urmia, Iran as an arid basin using satellite-based data. We estimated precipitation using interpolation of rain gauge data by kriging, downscaling Tropical Rainfall Measuring Mission (TRMM), and cokriging interpolation of in-situ records with Remote Sensing (RS)-based data. Using RS-based data in estimations gave more precise results, by compensating for lack of data at high elevations. Cokriging interpolation of rain gauges by TRMM and Digitized Elevation Model (DEM) gave 4–9 mm lower Root Mean Square Error (RMSE) in different years compared with kriging. Downscaling TRMM improved its accuracy by 14 mm. Using the most accurate precipitation model, we modeled annual direct runoff with Kennessey and Soil Conservation Service Curve Number (SCS-CN) models. These models use land use, permeability, slope maps and climatic parameter (Ia) to represent the annual climatic condition of modeled basin in sense of wetness or dryness. In runoff modeling, Kennessey gave higher accuracy in annual scale. It was found that classification of years to wet, dry and normal states in Kennessey by default assumptions on Ia is not accurate enough for semi-arid basins so by solving this issue and calibration Kennessey model parameters, we made this model applicable for Urmia Lake basin. Calibrating Kennessey reduced the Normalized RMSE (NRMSE) from 1 in the standard model to 0.44. Direct runoff coefficient map by 1 km spatial resolution was generated by calibrated Kennessey. Validation by the closest gauges to the lake gave a NRMSE of 0.41 which approved the accuracy of modeling.

How to cite: Akbari, M. and Torabi Haghighi, A.: Satellite Data Application to Cover Lack of In-situ Observations for Mapping Precipitation and Direct Runoff in Semi-arid Basin, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-13666, https://doi.org/10.5194/egusphere-egu2020-13666, 2020.

EGU2020-3018 | Displays | HS2.2.1

Evidence-based conceptual requirements of regional groundwater processes for hydrological simulations

Louisa Oldham, Jim Freer, Gemma Coxon, Nicholas Howden, John Bloomfield, and Christopher Jackson

River flows are the result of dynamically changing, interacting and non-linear processes of surface, near subsurface and often deeper groundwater flow from climatic drivers. Conceptual rainfall-runoff models, whilst providing advantages in computational efficiency and more minimal data requirements, often struggle to simulate contributions from groundwaters, resulting in poor model calibration. Improving predictions of river flows in these catchments is, however, critical to water resources planning and management, particularly in the UK where groundwater contributes 30% of public water supply in England. In order to improve model predictions in groundwater-dominated catchments, we conduct a detailed analysis of available observational data to better understand groundwater-surface water interactions and processes on a regional (aquifer) and local (river reach) scale, over geologically variable areas.

National meteorological, hydrological, hydrogeological, geological and artificial influence (characterising abstractions and return flows) datasets are used to develop a conceptualisation of the groundwater processes occurring in 99 subcatchments of the River Thames in the UK. We use these data to characterise the water balance, intercatchment groundwater flows, gaining/losing river reaches and hydrograph dynamics of these subcatchments, and investigate how dominant groundwater processes vary spatially and temporally. The River Thames has been selected as our case study owing to its wealth of data, densely gauged river network and geological variability.

We show that intercatchment groundwater flow is needed to ‘close’ the water balance in many catchments located on aquifer outcrops and find evidence of river-groundwater level flow thresholds. Importantly, we find that seasonality is a key control on the accurate representation of groundwater-surface water interaction processes and that the spatial and temporal variability of those processes varies greatly for different geologies across the Thames basin. We also demonstrate the importance of human influences to understand some of these spatial processes. We then identify the physical processes that existing conceptual rainfall-runoff models are likely missing, and what may be required to enable model calibration improvements in groundwater-dominated catchments.

How to cite: Oldham, L., Freer, J., Coxon, G., Howden, N., Bloomfield, J., and Jackson, C.: Evidence-based conceptual requirements of regional groundwater processes for hydrological simulations, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-3018, https://doi.org/10.5194/egusphere-egu2020-3018, 2020.

EGU2020-3807 | Displays | HS2.2.1

Evaluation of the joint effects of DEM resolution and calculation cell size on discharge simulation performance with two routing methods

Jingjing Li, Hua Chen, Chong-Yu Xu, Haoyuan Zhao, Lu Li, Jie Chen, and Shenglian Guo

Benefit from the easy access to gridded hydrological datasets and global Digital Elevation Model (DEM) datasets, DEM-based routing methods have been widely developed and used. The routing methods can be divided into two categories, i.e., Source-to-Sink and Cell-to-Cell. Limited by the computation capabilities, routing methods are often performed at more coarse resolution of calculation cell rather than the resolution of DEM. Both the DEM resolution and calculation cell-size are factors that affect the discharge simulation performance of routing method. Too little work has been devoted to how these two factors affect routing performance jointly. This study aims to compare the effects of DEM resolution and calculation cell-size on discharge simulation performance with two most popular routing methods, including a Cell-to-Cell routing method, i.e., Liner-reservoir-routing method (LRR) and a Source-to-Sink routing method, i.e., the improved aggregated network-response function routing method (I-NRF). They are compared/evaluated in terms of the changes of simulation performance with calculation cell-size ranging from 5 arc-minutes to 60 arc-minutes and DEM resolutions of 90 m×90 m, 250 m×250 m, 500 m×500 m, 1000 m×1000 m. Besides, two hydrological runoff-generation models and two study basins are used to test the generality of the result. The study finding will help the researchers to choose the appropriate DEM resolution, calculation cell-size and routing method in hydrological simulation.

How to cite: Li, J., Chen, H., Xu, C.-Y., Zhao, H., Li, L., Chen, J., and Guo, S.: Evaluation of the joint effects of DEM resolution and calculation cell size on discharge simulation performance with two routing methods, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-3807, https://doi.org/10.5194/egusphere-egu2020-3807, 2020.

EGU2020-8172 | Displays | HS2.2.1

Operational hydrology in highly steep areas: evaluation of tin-based toolchain

Olga Silantyeva, John F. Burkhart, Bikas C. Bhattarai, Ola Skavhaug, and Sigbjørn Helset

Triangular Irregular Network (TIN) is known to be an efficient way to represent surface topography (Marsh et al. 2018). However, little attention has been given to assess direct benefits of the TIN-based terrain representation in operational hydrology. We connect Shyft-hydrology, a part of Shyft open-source project dedicated to distributed hydrologic modelling in operational environments, with Rasputin software intended for conversion of digital elevation models into simplified triangular meshes. Shyft is known for its high flexibility: the framework lets researcher test different functioning hypothesis with very little programming effort. We implemented new routine in Shyft-hydrology, which allows translation of solar radiation onto inclined surfaces based on (Allen et al. 2006). Thus, Shyft and Rasputin is a unique toolchain to study impact of hillslope variations in solar radiation onto snowmelt, evapotranspiration and discharge simulation.

We conducted several experiments on subcatchments of Narayani river located in Central Nepal. This area is known to be very steep, with meteorological stations, located mainly in the low-land. The re-analysis data for the area is coarse and prone to different kind of issues (Bhattarai et al 2020). The outcomes are promising: tin-based solution outperfoms regular grid, when running with Shyft-hydrology model most used in the operations. The new model with translated radiation also works well, giving us no decrease in performance of discharge simulations, but some more insights in snow modelling. We clearly see, what we expect from observations: sunny slopes melt earlier while shady ones keep snow for longer periods.

Acknowledgments. This project contributes to LATICE (Land Atmosphere Interaction in Cold Environments) initiative at the University of Oslo.

References

Marsh, C. B., Spiteri, R. J., Pomeroy, J. W., and Wheater, H. S.: Multi-objective unstructured triangular mesh generation for use in hydro- logical and land surface models, Computers and Geo- sciences, 119, 4967, 2018.

Richard G. Allen, Ricardo Trezza, and Masahiro Tasumi. Analytical integrated functions for daily solar radiation on slopes. Agricultural and Forest Meteorology, 139:5573, 2006.

Bhattarai, B. C., Burkhart, J. F., Tallaksen, L. M., Xu, C.-Y., and Matt, F. N.: Evaluation of forcing datasets for hydropower inflow simulation in Nepal, Accepted for publication. Hydrology research, 2020

How to cite: Silantyeva, O., Burkhart, J. F., Bhattarai, B. C., Skavhaug, O., and Helset, S.: Operational hydrology in highly steep areas: evaluation of tin-based toolchain, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-8172, https://doi.org/10.5194/egusphere-egu2020-8172, 2020.

Characterizing soil volumetric water content (VWC) dynamics at different soil depth plays a key role in hydrological modeling and is essential for effective catchment management. However, our understanding of how critical zone structure (topography and soil) and rainfall affect VWC dynamics is limited. Therefore, the objective of this study was to investigate the effects of the hillslope structure and rainfall on VWC dynamics in a steep forested, zero-order catchment. VWC was measured from soil surface to soil-bedrock interface at five soil layers (0-8, 8-40, 40-70, 70-110, and 110-160 cm) for a complete water year, and covering various landscapes such as an ephemeral stream, riparian, and different hillslope positions. A total of 13 environmental indices, including eight DEM-derived terrain attributes and five soil attributes, were used to investigate the relationships between soil-terrain attributes and VWC. An all-possible-subsets regression model was adopted to construct the soil water content prediction model (SWPM). A geophysical method (ground penetrating radar, GPR) was used to investigate the soil depth to assist in the establishment of SWPM. The results demonstrate that the all-possible-subsets regression model performed well for predicting VWC. Additionally, the strength of the relationships between soil-terrain attributes and VWC could be different through time. For instance, the relationships between the topographic wetness index (TWI) and VWC were all significant (P<0.05) from August to October, whereas the correlation between TWI and VWC was not significant (P≥0.05) at approximately 25% of measurement days from November to February. The results also show that the high correlation between terrain-related attributes and VWC usually occurs in the measurement days with high catchment storage state, whereas the high correlation between soil-related attributes and VWC more often occurs in the measurement days with low catchment storage state. Therefore, the control factors of VWC spatial organization vary from humid (controlled by topographic redistribution of water) to arid (controlled by vertical processes such as evapotranspiration) seasons.

How to cite: Han, X. and Liu, J.: Seasonal controls of soil water content spatial pattern in a steep forested catchment: A modeling approach, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-12404, https://doi.org/10.5194/egusphere-egu2020-12404, 2020.

EGU2020-12045 | Displays | HS2.2.1

High resolution data for semi-distributed hydrological modeling: where should we draw the line?

Etienne Foulon, Alain N. Rousseau, Eduardo J. Scarpari Spolidorio, and Kian Abbasnezhadi

High-resolution data are readily available and used more than ever in hydrological modeling, despite few investigations demonstrating the added value. Nonetheless, a few studies have looked into the benefits of using increased spatial resolution data with the widely-used, semi-distributed, SWAT model. Meanwhile, far too little attention has been paid to the physically-based, semi-distributed, hydrological model HYDROTEL which is widely used for hydrological forecasting and hydroclimatic studies in Quebec, Canada. In a preliminary study, we demonstrated that increasing the spatial resolution of the digital elevation model (DEM) had a significant impact on the discretization of a watershed into hillslopes (i.e., computational units of HYDROTEL), and on their topographic attributes (slope, elevation and area). Accordingly, values of the calibration parameters were also substantially affected; whereas model performance was slightly improved for high- and low-flows only. This is why, we hereby propose the systematic assessment of HYDROTEL with respect to the resolution of the spatiotemporal computational domain for a specific physiographic scale. This investigation was conducted for the 350-km2 St. Charles River watershed, Quebec, Canada. The DEM used was derived from LiDAR data and aggregated at 20 m. Due to a lack of accurate precipitation information at time scales less than 24 hr, data from the high resolution deterministic precipitation analysis system, CaPA-HRDPA, were used to generate various time steps (6, 8, 12, and 24 hr) and to control results obtained from observed data. This approach, recently applied to three watersheds in Yukon, proved to be an excellent alternative to calibrate a hydrological model in a region known as a hydometeorological desert (see EGU 2020 presentation of Abbasnezhadi and Rousseau). The number of computational units ranged between 5 to 684 hillslopes, with mean areas ranging from 75 km2 to 0.5 km2. HYDROTEL was automatically calibrated over the 2013-2018 period using PADDS. We combined the Kling Gupta Efficiency and the log-transformed Nash Sutcliffe Efficiency to ensure good seasonal and annual representations of the hydrographs. The 12 most sensitive calibration parameters were adjusted using 150 optimisation trials with 150 repetitions each. Behavioral parameters were used to assess uncertainty and ensuing equifinality. All scenarios were evaluated using flow duration curves, performance indicators (RMSE, % Bias) and hydrograph analyses. In addition, quantitative analyses were done with respect to physiographic features such as: length of river segments, hillslopes, and sub-watershed boundaries for each resolution. We believe this study provides the needed systematic framework to assess trade-offs between spatiotemporal resolutions and modeling performances that can be achieved with HYDROTEL. Moreover, the use of various numbers of CaPA-HRDPA stations for model calibration has allowed us to determine the number of precipitation stations needed to achieve a given performance threshold.

How to cite: Foulon, E., Rousseau, A. N., Scarpari Spolidorio, E. J., and Abbasnezhadi, K.: High resolution data for semi-distributed hydrological modeling: where should we draw the line?, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-12045, https://doi.org/10.5194/egusphere-egu2020-12045, 2020.

EGU2020-18628 | Displays | HS2.2.1

It's impolite to zoom in on global hydrological models

Jerom Aerts, Albrecht Weerts, Willem van Verseveld, Niels Drost, Rolf Hut, and Nick van de Giesen

Large scale or global hydrological models (GHMs) show promise in enabling us to accurately predict floods, droughts, navigation hazards, reservoir operations, and many more water related issues. As opposed to regional hydrological models that have many parameters that need to be calibrated or estimated using local observation data (Sood and Smakhtin 2015). GHMs are able to simulate regions that lack observation data, whilst applying a uniform approach for parameter estimation (Döll, Kaspar, and Lehner 2003; Widén‐Nilsson et al. 2009). Up until recently the GHMs used coarse modelling grids of around 0.5 to 1 degree spatial resolution. However, due to advances in satellite data, climate data, and computational resources, GHMs are modelling on higher resolutions (up to 200 meters) that raise questions about how these models can be adjusted in order to take advantage of the finer modelling grid.

In this study, we carry out an extensive assessment of how changes in spatial resolution affect the simulations of the Wflow SBM model for 8 basins in the Continental United States. This is done by comparing the model states and fluxes at three spatial resolutions, namely 3 km, 1km, and 200m. A hypothesis driven approach is used to investigate why changes in states and fluxes are taking place at different spatial resolutions and how they relate to model performance. The latter is determined by validating river discharge, snow extent, soil moisture, and actual evaporation. In addition, we make use of two sets of parameters that rely on different pedo-transfer functions. Further investigating the role parameterization in conjunction with changes in spatial resolution.

By carrying out this study within the eWaterCycle II framework we showcase our ability to handle large datasets (forcing and validation) whilst always complying to the FAIR principles. Furthermore, this study is setup in such that it is scalable in terms of case study areas and hydrological models.

How to cite: Aerts, J., Weerts, A., van Verseveld, W., Drost, N., Hut, R., and van de Giesen, N.: It's impolite to zoom in on global hydrological models, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-18628, https://doi.org/10.5194/egusphere-egu2020-18628, 2020.

EGU2020-6543 | Displays | HS2.2.1

The impact of interpolation method on the accuracy of meteorological variables in distributed hydrological model

Jiajia Liu, Zuhao Zhou, Ziqi Yan, Yangwen Jia, and Hao Wang

Precipitation and other meteorological variables are very important input data for distributed hydrological models, which determine the simulation accuracy of the models. It is a normal way to subdivide the large area watershed into numerous subbasins to reflect the spatial variation, and the value is usually unique within each subbasin. In most model application, the values of meteorological variables are interpolated from meteorological station observed data to the centroid point of the subbasin with interpolation method (called one-cell interpolation). Because the centroid point could not represent the whole subbasin, the one-cell interpolation will bring input data uncertainty to the model. In this study, a new method is introduced to analysis this uncertainty, which firstly interpolate the values into numerous cells smaller than the subbasin then sum up to the subbasin (called multi-cells interpolation). The results show that one-cell interpolation way is not always consistent with the results of multi-cells interpolation, and the variance is greater in summer than in winter. The consistency grows with the increase of the number of the cells, which indicates that dozens of the cells could got the stable state. The variance is also influenced by the density of meteorological station, but the minimal cell number is almost the same. Thus, in the interpolation of the meteorological variables in distributed hydrological model, it recommends to interpolate the values to numerous smaller cells then sum up to the subbasins, rather than only interpolate to the centroid point.

How to cite: Liu, J., Zhou, Z., Yan, Z., Jia, Y., and Wang, H.: The impact of interpolation method on the accuracy of meteorological variables in distributed hydrological model, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-6543, https://doi.org/10.5194/egusphere-egu2020-6543, 2020.

EGU2020-13402 | Displays | HS2.2.1

Distributed hydrological modelling using spatiotemporally varying velocities

Konstantina Risva, Dionysios Nikolopoulos, and Andreas Efstratiadis

We present a distributed hydrological model with minimal calibration requirements, which represents the rainfall-runoff transformation and the flow routing processes. The generation of surface runoff is based on a modified NRCS-CN scheme. Key novelty is the use of representative CN values, which are initially assigned to model cells on the basis of slope, land cover and permeability maps, and adjusted to antecedent soil moisture conditions. For the propagation of runoff to the basin outlet two flow types are considered, i.e. overland flow across the terrain and channel flow along the river network. These are synthesized by employing a novel velocity-based approach, where the assignment of velocities along the river network is based on macroscopic hydraulic information. It also uses the concept of varying time of concentration, which is considered function of the average runoff intensity across the catchment. This configuration is suitable for event-based flood simulation and requires the specification of only two lumped inputs, which are either manually estimated or inferred through calibration. The model can also run in continuous mode, by employing a soil moisture accounting scheme that produces both the surface (overland) runoff and the interflow through the unsaturated zone. The two model configurations are demonstrated in the representation of observed flows across Nedontas river basin at South Peloponnese, Greece.

How to cite: Risva, K., Nikolopoulos, D., and Efstratiadis, A.: Distributed hydrological modelling using spatiotemporally varying velocities, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-13402, https://doi.org/10.5194/egusphere-egu2020-13402, 2020.

Precipitation is a key factor in controlling the accuracy of runoff simulation, as well as the performance of flood event simulation. Compared with the in-situ rainfall measurement, satellite-based precipitation products provide critical precipitation sources of higher resolution along with detailed depiction of precipitation variability, especially for data-sparse or ungauged regions. This study aims to investigate the impacts of temporal and spatial resolutions of precipitation on flood simulation over a humid region of Southern China. Three versions of Integrated Multi-satellite Retrievals for GPM (IMERG-E, IMERG-L, and IMERG-F) and a gauge-satellite merged precipitation product released by China Meteorological Administration (CMA) at 0.1° and 1 h resolution are used in the study. The lumped hydrological model HBV and semi-distributed hydrological model SWAT are applied to simulate 12 flood events to investigate the impacts of temporal and spatial variabilities of precipitation on flood event simulation. The results show that the spatial resolution of precipitation data affects its capture of characteristics of precipitation events, specifically in magnitude of precipitation variability and the central location of the precipitation event. Furthermore, SWAT shows no improvement compared with HBV in flood event simulation in this case, which may due to the uncertainty of the precipitation spatial variability. The flood events simulated with SWAT indicate that the biases of flood peaks forcing by IMERG-E and IMERG-L increase with the decreasing of precipitation variability, while that forced by IMERG-F are less affected and perform the best among the three IMERG precipitation estimates. The impact of temporal variability of precipitation is conducted with HBV model and the corresponding results are that the higher temporal resolution ensures the better flood event simulation. Furthermore, the CMA source overperforms the other three satellite-based precipitation estimates, and followed by IMERG-F.

How to cite: Zhu, Q. and Zhou, D.: Impacts of spatio-temporal precipitation variabilities on flood event simulation with satellite-based precipitation estimates, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-6989, https://doi.org/10.5194/egusphere-egu2020-6989, 2020.

EGU2020-13384 | Displays | HS2.2.1

Integrated modelling: a tool for combining findings from multiple studies in a hydrologic observatory

Lovrenc Pavlin, Borbála Széles, Alfred Paul Blaschke, and Günter Blöschl

Research catchments allow a unique opportunity of acquiring long and varied datasets. This process takes years and is often performed by multiple generations of researchers with different research focuses. In this way, complex processes might be identified and explained on a variety of spatial and temporal scales. But how could these puzzle pieces be put together to form the complete picture of the catchment and would they even fit? Physically-based integrated surface-subsurface models, such as HydroGeoSphere, give us the possibility to jointly model a wide array of processes informed by measurable parameters. Here we present the ongoing work on conceptual models testing by an integrated model in the Hydrological open air laboratory (HOAL). This is a small headwater agricultural catchment in Lower Austria, where a variety of hydrometeorological and hydrogeochemical parameters are monitored with high spatial and temporal resolution. The model in this study builds on the conceptual models of previous studies in the catchment and incorporates features such as tile drainage system, macropores, variable land use and regional groundwater flow. Groundwater levels and discharge data at the tributaries and the catchment outlet from 2013-2017 were used for calibration. We discuss the preliminary findings and the advantages and disadvantages of this modelling approach.

How to cite: Pavlin, L., Széles, B., Blaschke, A. P., and Blöschl, G.: Integrated modelling: a tool for combining findings from multiple studies in a hydrologic observatory, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-13384, https://doi.org/10.5194/egusphere-egu2020-13384, 2020.

EGU2020-18236 | Displays | HS2.2.1

Development of simple distributed hydrological model based on soil moisture simulation

Jiyu Seo, Jeonghyeon Choi, and Sangdan Kim

One of challenges to hydrologists is to estimate runoff from ungauged watershed. Hydrologic estimation through modelling is a reasonable, economical and useful approach to quantity and quality management of watershed. The model framework has been comprehensive and complex to reproduce natural phenomena more realistically with the development of computer hardware. However, driving a complex model requires a lot of effort and time, and the use of many parameters reduces the accessibility of end users and the applicability to the ungauged watershed. In this study, we developed a distributed hydrologic model based on soil moisture simulation using simple composition and fewer parameters. Instead of minimizing the number of parameters, GIS data were used to reflect the watershed characteristics into the model. The proposed model was applied to the four dam watersheds in Korea to assess its performance. As a result, it is confirmed that reasonable hydrologic components simulation is possible through the simulation of soil moisture, even though it was a simple model with only three input parameters. If spatial data such as satellite data is additionally applied, the performance of the model is expected to improve further.

Acknowledgment: This work was supported by Korea Environment Industry & Technology Institute(KEITI) through Public Technology Program based on Environmental Policy Project, funded by Korea Ministry of Environment(MOE)(2016000200002).

Keywords: Distributed hydrological model; Hydrologic components simulation; Soil moisture; Simple hydrological model.

How to cite: Seo, J., Choi, J., and Kim, S.: Development of simple distributed hydrological model based on soil moisture simulation, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-18236, https://doi.org/10.5194/egusphere-egu2020-18236, 2020.

EGU2020-3101 | Displays | HS2.2.1

How to adapt a nonurban model structure to account for urbanization?

Mohamed Saadi, Ludovic Oudin, and Pierre Ribstein

A catchment-scale hydrological model encompasses a set of hypotheses that are capable of describing, in a lumped way, the water movement in a hydrological catchment. As the catchment undergoes a heavy urbanization gradient, the catchment’s hydrological behavior changes. A new set of hypotheses is then needed to consider the presence of urban-introduced features in the hydrological cycle. Our objective is to reach a parsimonious model structure that is capable of sufficiently reproducing the rainfall-runoff relationship along a wide range of urbanization levels, including the non-urbanized situation. Given a model that is adequate for non-urbanized catchments, what modifications should one operate on the initial model hypotheses to account for (1) the presence of impervious surfaces within the catchment and (2) the interactions between the pervious and the newly added impervious surfaces? To this aim, a large sample of 268 American and French urbanized catchments was prepared. We have chosen an initial hydrological model, GR4H, whose structure has been tested and improved using large international samples of catchments, but predominately non-urbanized. Analyzing the hydrological behavior of the urbanized catchments has helped us in formulating a set of modifications to be made on the initial model structure. Step by step, the relevance of each modification was assessed using 10 continuous, frequency- and event-based evaluation criteria. As a result, the model performances were significantly improved when (a) the net rainfall production was considered to be controlled not only by the antecedent soil moisture conditions but also by the catchment’s mean imperviousness, mainly during low-intensity rainfall events, and (b) the fast flow branch was more privileged in routing, seeing that the response of the urbanized catchments was faster and highly reactive in comparison with the rural ones’. Unlike the initial model structure, the resulting one can help quantifying the impact of future urbanization schemes on the catchment’s hydrological behavior.

How to cite: Saadi, M., Oudin, L., and Ribstein, P.: How to adapt a nonurban model structure to account for urbanization?, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-3101, https://doi.org/10.5194/egusphere-egu2020-3101, 2020.

EGU2020-4222 | Displays | HS2.2.1

DWBmodelUN: an R-package for the hydrological model Dynamic Water Balance

Camila García-Echeverri, Nicolás Duque-Gardeazabal, Carolina Vega-Viviescas, Pedro Arboleda-Obando, and David Zamora

Evapotranspiration (ET) is one of the most important factors for the water budget and physical processes in the tropical region. This variable affects the atmospheric water and it is important for its capacity to control precipitation, including its influence on absorption and reflection of solar and terrestrial radiation. In the tropical context ET is a relevant process, where the condensation of large amounts of water vapor leads to the release of latent heat energy. In order to understand ecohydrological and climatic synergies and interactions in the tropical basins, different models have tried to represent the hydrological processes in time and space. But most of these models depend on variables that should be measured in situ and are rarely available or limited in the tropical countries. This inevitably requires the model to be simple enough and the parameters can be estimated from climate and basin characteristics. In this regard, Zhang et al. (2008) developed a hydrological model Dynamic Water Balance (DWB). DWB is a semi-distributed model supported in the Budyko framework, which uses partition curves to distribute water to a number of components based on water availability and demand concepts. In general, the model assumes the control over the water balance is mostly dominated by the precipitation (P) and potential evapotranspiration. 

The hydrologic structure of DWB consists of two tanks, soil moisture store and groundwater store, and adjust its mathematical relations through the optimization of four parameters. Due to its simplicity and strong concepts, DWB had been implemented successfully in several types of basins around the globe (Rodriguez et al., 2019).

This work presents DWBmodelUN, a hydrological R-package with the implementation of DWB in a regular mesh at a monthly time step. DWBmodelUN contains 12 functions related to data entry pre-processing, mathematical development of DWB, calibration algorithm Dynamical Dimension Search and an interactive graphical  module. In overall terms, DWBmodelUN requires: (i) basin geographic data (defines the spatial resolution of the modelling), (ii) hydro-meteorological entry data (P, Temperatute, Streamflow) in raster format, (iii) initial values for the model parameters and (iv) setup data such as warm up, calibration and validation periods. 

In addition, this package includes a practical example of application in Sogamoso River Basin, located at the Oriental mountain range of Colombia.  Therefore, data sets with hydrological, meteorological and setup information were incorporated within the package.

This tool intents to spread  the DWB model and facilitate its implementation in more basins. In this context, to execute DWBmodelUN users do not need extensive programming skills and the R-package was thought for easily adaptability.

References

Rodríguez, E., Sánchez, I., Duque, N., Arboleda, P., Vega, C., Zamora, D., … Burke, S. (2019). Combined Use of Local and Global Hydro Meteorological Data with Hydrological Models for Water Resources Management in the Magdalena - Cauca Macro Basin – Colombia. Water Resources Management. 

Zhang, L., Potter, N., Hickel, K., Zhang, Y., & Shao, Q. (2008). Water balance modeling over variable time scales based on the Budyko framework – Model development and testing. Journal of Hydrology, 360(1–4), 117–131. 

How to cite: García-Echeverri, C., Duque-Gardeazabal, N., Vega-Viviescas, C., Arboleda-Obando, P., and Zamora, D.: DWBmodelUN: an R-package for the hydrological model Dynamic Water Balance, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-4222, https://doi.org/10.5194/egusphere-egu2020-4222, 2020.

airGR (Coron et al., 2017, 2019) is an R package that offers the possibility to use the GR rainfall-runoff models developed in the Hydrology Research Group at INRAE (formerly at Irstea), including the daily GR4J model as well as hourly, monthly and annual models. Recent model developments are regularly introduced in airGR.

Recently, an hourly model including an interception store was implemented in airGR. The additional interception store, developed by Ficchi et al. (2019), aims at better representing the impact of vegetation on evaporation fluxes. This improved model showed a better consistency of model fluxes across time and enhanced performance.

In addition, the possibility to run the hourly GR models together with the CemaNeige snow accumulation and melt module was added to airGR.

 

References:

Coron L., Thirel G., Delaigue O., Perrin C., Andréassian V. (2017). The Suite of Lumped GR Hydrological Models in an R package, Environmental Modelling & Software, 94, 166-171. DOI: 10.1016/j.envsoft.2017.05.002.

Coron, L., Delaigue, O., Thirel, G., Perrin, C. and Michel, C. (2019). airGR: Suite of GR Hydrological Models for Precipitation-Runoff Modelling. R   package version 1.4.3.30. URL: https://CRAN.R-project.org/package=airGR.

Ficchì, A., Perrin, C., and Andréassian, V., 2019. Hydrological modelling at multiple sub-daily time steps: model improvement via flux-matching, Journal of Hydrology, 575, 1308-1327, https://doi.org/10.1016/j.jhydrol.2019.05.084.

How to cite: Thirel, G., Delaigue, O., and Ficchi, A.: Latest developments of the airGR rainfall-runoff modelling R-package: inclusion of an interception store in the hourly model, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-15275, https://doi.org/10.5194/egusphere-egu2020-15275, 2020.

EGU2020-477 | Displays | HS2.2.1

Web-based hydrological modelling tool - Hidro-Odtu

Çağrı Hasan Karaman, Zuhal Akyürek, and Kenan Bolat

Bucket-type conceptual hydrological models are widely popular, because of their relatively low data and computational demands. With the improved computational techniques and advances in computer sciences, web based hydrological modelling tools are becoming available too. Conceptual rainfall-runoff (CRR) models are designed to approximate the general physical mechanisms which govern the hydrologic cycle and found practical by many hydrologists and engineers. In this context, a web based, open-source, platform independent, easily accessible hydrological modelling tool Hidro-Odtu has been designed. Aiming at providing fast and accurate results, Hidro-Odtu utilize lumped and semi-distributed hydrological modelling capabilities. The design of the Hidro-Odtu contains pre-processing using the tools to automatically delineate the river network and basin boundaries, input the forcing data, lumped hydrological modelling with parameter calibration capability, hydrological overland flow routing and dynamic result visualization. Moreover, web-based technologies allow remotely prepare model input files, run model calculation and display model results for rainfall-runoff calculations. Bucket storage lumped, conceptual rainfall-runoff model is selected as core feature for hydrological model and it is enhanced to a semi-distributed model by including the Muskingum-Cunge flow routing method to simulate overland flow. Model results are evaluated by several performance indices such that Nash–Sutcliffe Efficiency Index (NSE), Sum of Square of Error (SSE) or Kling-Gupta Efficiency (KGE).

Hydrological modelling, calibration and routing algorithms have been implemented by using Python programming language for the back-end calculations and Node.js framework, html, JavaScript have been utilized for front-end side to handle data preparation and results visualization.

Hidro-Odtu have been evaluated with numerous data sets with different study areas and found successful to delineate sub basins and river network, to define rainfall-runoff relationship on the basis of the sub-basins. With this tool, it is aimed to obtain practical hydrological modelling results using web technologies.

How to cite: Karaman, Ç. H., Akyürek, Z., and Bolat, K.: Web-based hydrological modelling tool - Hidro-Odtu, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-477, https://doi.org/10.5194/egusphere-egu2020-477, 2020.

In 2008, Buytaert et al. asked: “Why can’t we do better than TOPMODEL?” Their answer based on the development of a new generation of hydrological modelling tools, which should be accessible, portable and, especially, modular. Such modular modelling frameworks have now been developed and are used to test hypotheses of catchment behaviour. Some of these frameworks are limited to lumped models, like FUSE, SuperFLEX and MARRMoT, or allow the construction of semi-distributed models like RAVEN. Lumped and semi-distributed models are, due to their little computational costs, great tools for exploring parametric and structural model uncertainty. However, lumped and semi-distributed models are based on the intrinsic hypothesis that the internal spatial configuration of a catchment is not relevant for the runoff processes in a catchment. This assumption of the model structure cannot be scrutinized inside of these frameworks. Modelling systems with the potential to build distributed models, representing the spatial connectivity of landscape features, are eg. SUMMA and CMF.

Our modular, open access Catchment Modelling Framework (CMF, https://philippkraft.github.io/cmf/) is implemented as a library of water fluxes along the nodes of a hydrological network across spatial and temporal scales. It facilitates building models representing current process understanding. It is written in C++ as a library of the Python programming language and is supported and constantly extended since 2009. Due to the open nature, models build with CMF can be adopted to data structure and qualitative expert knowledge. The CMF library contains classical equations of water flux from the Nash-Box to the Richard’s equation. Often neglected anthropogenic infrastructures and activities like sewage water plants, reservoirs, irrigation and pumping can be represented with user-supplied functions. As a library, the connection to other model domains is possible, e.g. plant growth or soil chemistry models, where CMF acts as a water and solute transport module and other models as dynamic boundary conditions.

We will illustrate the use of the library concept with some applications:

  • Plot scale (100 m²): Macropore solute transport
  • Field scale (102 m²): Feedback loops between CO2 effect in crops and soil water availability
  • Hillslope (104 m²): Integrated nitrogen turnover and transport model
  • Riparian zone of a continental stream (107 m²): A distributed groundwater model to predict plant species habitats under climate change
  • Catchment (108 m²): Spatial explicit risk assessment of open water bodies to pesticide spray drift
  • Catchment (109 m²): Incremental break down of a lumped model

How to cite: Kraft, P. and Breuer, L.: Representing dynamic networks of water flow in space, time and structure using process libraries, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-17050, https://doi.org/10.5194/egusphere-egu2020-17050, 2020.

EGU2020-12985 | Displays | HS2.2.1

Characterizing Hydrological Fluxes of Lesser Himalayan hillslopes

Aliva Nanda and Sumit Sen

Hillslope-scale studies play a vital role in understanding the spatial and temporal dynamics of hydrological fluxes of an ungauged watershed. The linkage between static (i.e. topography, soil properties and landuse) and dynamic (i.e. runoff, soil moisture and temperature) characteristics of a hillslope provides a new insight towards hillslope processes. Thus, two Lesser Himalayan hillslopes of Aglar watershed have been selected in two different landuses (grass-covered and agro-forested) and aspects (south and north). In this study, we analyzed the different hydrological fluxes i.e. rainfall, runoff, soil moisture and soil temperature along with the soil properties to get a holistic understanding of hillslope processes. We used the soil moisture dynamics and soil hydraulic conductivity as the major components to derive the hillslope hydrological connectivity. It was observed that the grassed (GA) hillslope generates less runoff than the agro-forested (AgF) hillslope as the upslope runoff of GA hillslope re-infiltrated in the middle portion due to higher soil hydraulic conductivity and surface resistance. Further, this explains that the runoff contributing areas are located at the lower and upper portions of hillslopes due to the presence of low soil hydraulic conductivity zones.  As both the hillslopes are dominated with Hortonian overland flow, the negative correlation was found between topographic indices (TWI) and soil moisture and positive correlation was noticed between soil hydraulic conductivity. Higher runoff (less infiltration) from AgF hillslope results in a higher negative correlation between TWI and soil moisture in comparison to GA hillslope. This results in a higher rate of change in soil temperature of GA hillslope than the AgF hillslope. After analyzing 40 rainfall events, it was concluded that a temperature drop of more than 2oC was recorded when the average rainfall intensity and event duration exceeds 7.5mm/hr and 7.5hr, respectively. The understanding of covariance of these hydrological fluxes will be used in the future to develop a hillslope-scale conceptual model.

How to cite: Nanda, A. and Sen, S.: Characterizing Hydrological Fluxes of Lesser Himalayan hillslopes, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-12985, https://doi.org/10.5194/egusphere-egu2020-12985, 2020.

EGU2020-3713 | Displays | HS2.2.1

Improving the representation of the prairie pothole dynamics in land surface models

Mohamed I. Ahmed, Amin Elshorbagy, and Alain Pietroniro

The hydrography of the prairie basins is complicated by the existence of numerous land depressions, known as prairie potholes, which can retain a substantial amount of surface runoff. Consequently, the runoff production in the prairies follows a fill, spill, and merging mechanism, which results in a dynamic contributing area that makes the streamflow simulation challenging. Existing approaches to represent the potholes’ dynamics, in different hydrological models, use either a lumped or a series of reservoirs that contribute flow after exceeding a certain storage threshold. These approaches are simplified and do not represent the actual dynamics of the potholes nor their spatial water extents. Consequently, these approaches may not be useful in capturing the potholes’ complexities and may not be able to accurately simulate the complex prairie streamflow. This study advances towards more accurate and physically-based streamflow simulation in the prairies by implanting a physically-based runoff generation algorithm (Prairie Region Inundation MApping, PRIMA model) within the MESH land surface model, and is referred to as MESH-PRIMA. PRIMA is a recently developed hydrological routing model that can simulate the lateral movement of water over prairie landscape using topographic data provided via DEMs. In MESH-PRIMA, MESH handles the vertical water balance calculations, whereas PRIMA routes the water and determines the amount of water storage and surface runoff. The streamflow simulations of MESH-PRIMA (using different DEM resolution as a topographic input) and MESH with its existing conceptual pothole dynamics algorithm are tested on a number of pothole-dominated watersheds within Saskatchewan, Canada, and compared against observed flows. MESH-PRIMA provides improved streamflow and peak flow simulation, compared to that of MESH with its conceptual pothole algorithm, based on the metrics evaluated for the simulations. MESH-PRIMA shows potential for simulating the actual pothole water extents when compared against water areas obtained from remote sensing data. The use of different DEM resolution changes the resulting pothole water extent, especially for the small potholes as they are not detected in the coarse DEM. MESH-PRIMA can be considered as a hydraulic-hydrologic model that can be used for better understanding and accurate representation of the complex prairie hydrology.

How to cite: Ahmed, M. I., Elshorbagy, A., and Pietroniro, A.: Improving the representation of the prairie pothole dynamics in land surface models, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-3713, https://doi.org/10.5194/egusphere-egu2020-3713, 2020.

EGU2020-7060 | Displays | HS2.2.1

The relevance of preferential flow in catchment scale simulations

Luisa Hopp, Barbara Glaser, Julian Klaus, and Thilo Schramm

Despite experimental evidence preferential flow is rarely included in hydrologic catchment scale models. This is, at least partly, due to the challenge of deriving preferential flow parameters. Here, we successfully used the optimization algorithm DREAM to calibrate a 3D physics-based dual-permeability model directly at the catchment scale. We limited the number of parameters to be calibrated to the ones being most influential for the simulation of discharge, and we also calibrated parameters of the matrix domain and the macropore domain with a fixed parameter ratio between soil layers. During calibration, saturated hydraulic conductivities of the macropore domain and of the matrix domain converged to very similar values. The dual-permeability parameter sets also did not outperform a calibrated single-domain reference model scenario. We conclude that the incorporation of vertical preferential flow as represented by the dual-permeability approach was not advantageous for reproducing the hydrometric response reasonably well in the studied catchment.

How to cite: Hopp, L., Glaser, B., Klaus, J., and Schramm, T.: The relevance of preferential flow in catchment scale simulations, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-7060, https://doi.org/10.5194/egusphere-egu2020-7060, 2020.

EGU2020-13582 | Displays | HS2.2.1

Development of a semi-distributed hydrological model on a tidal-affected river: application to the Adour catchment, France.

Valentin Mansanarez, Guillaume Thirel, Olivier Delaigue, and Benoit Liquet

Streamflow estimation from rain events is a delicate exercise. Watersheds are complex natural systems and their response to rainfall events is influenced by many factors. Hydrological rainfall-runoff modelling is traditionally used to understand those factors by predicting discharges from precipitation data. These models are simplified conceptualisations and thus still struggle when facing some particular processes linked to the catchment. Among those processes, the tide influence on river discharges is rarely accounted for in hydrological modelling when estimating streamflow series at river mouth areas. Instead, estimated streamflow series are sometimes corrected by coefficients to account for the tide effect.

In this presentation, we explored a semi-distributed hydrological model by adapting it to account for tidal-influence in the river mouth area. This model uses observed spatio-temporal rainfall and potential evapotranspiration databases to predict streamflow at gauged and ungauged locations within the catchment. The hydrological model is calibrated using streamflow observations and priors on parameter values to calibrate each model parameters of each sub-catchments. A drift procedure in the calibration process is used to ensure continuity in parameter values between upstream and downstream successive sub-catchments.

This novel approach was applied to a tidal-affected catchment: the Adour’s catchment in southern France. Estimated results were compared to simulations without accounting for the tidal influence. Results from the new hydrological model were improved at tidal-affected locations of the catchment. They also show similar estimations in tidal-unaffected part of the catchment.

How to cite: Mansanarez, V., Thirel, G., Delaigue, O., and Liquet, B.: Development of a semi-distributed hydrological model on a tidal-affected river: application to the Adour catchment, France., EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-13582, https://doi.org/10.5194/egusphere-egu2020-13582, 2020.

EGU2020-21338 | Displays | HS2.2.1

Baseflow measurement and analysis of Nakdong River in South Korea

Ryoungeun Kim and Sangdan Kim

The Nakdong River is the longest river in Korea with watersheds throughout the Yeongnam region of Korea, and plays an important role as a water source for agricultural water, water supply and industrial water. There is a growing recognition that baseflow measurements are important for effective water management in these large watersheds. To effectively quantify baseflow, specific conductance (SC) data is used, the most effective parameter collected continuously. The baseflow is effectively measured by using SC data and watershed information such as runoff and precipitation for tank model and soil and water assessment tool (SWAT). Our results show that a management approach that considers surface water as well as subsurface water as a resource is important for the effective management of current and future water resources.

This work was supported by the National Research Foundation of Korea (NRF) grant funded by the Korea government (MSIT) (No. NRF-2019R1A2C1003114).

How to cite: Kim, R. and Kim, S.: Baseflow measurement and analysis of Nakdong River in South Korea, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-21338, https://doi.org/10.5194/egusphere-egu2020-21338, 2020.

EGU2020-8346 | Displays | HS2.2.1

An approach to accommodate and estimate antecedent moisture in runoff curve number methodology- An experimental study

Surendra Kumar Mishra, Ishan Sharma, Ashish Pandey, and Shailendra Kumar Kumre

Modelling of the event-based rainfall-runoff process has considerable importance in Hydrology, especially for assessment of water yield potential of a watershed, planning of soil and water conservation measures, reducing sedimentation, and flooding hazards downstream. Antecedent moisture (M) plays a significant role in governing the rainfall-runoff modelling process. It has been the focal point of research in the last decade for improving the Soil Conservation Service Curve Number (SCS-CN) method (also known as NRCS-CN method) for surface runoff computation. In this study, an innovative procedure is proposed to accommodate M in the basic structure of the SCS-CN methodology which otherwise was incorporated externally; to compute M using rainfall-runoff data and verify its applicability by comparing M with the in-situ soil moisture.

Natural rainfall, runoff, and soil moisture data from 6 small experimental farms with different land-use viz. Maize, Finger Millet, and Fallow land, located at Roorkee, India, are utilized. The M is computed by optimizing two parameters, i.e., absolute maximum potential retention (Sabs) and initial abstraction ratio (λ), and the optimization is accomplished by minimizing the root mean square error (RMSE). Results show that there exists a good correlation between theoretical M and measured in-situ moisture. Also, the optimized value of λ has the less error in computing M than the other standard values of λ (λ = 0.2; λ= 0.03). This study not only improves the SCS-CN method but also widens its application horizon in soil moisture studies.

How to cite: Mishra, S. K., Sharma, I., Pandey, A., and Kumre, S. K.: An approach to accommodate and estimate antecedent moisture in runoff curve number methodology- An experimental study, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-8346, https://doi.org/10.5194/egusphere-egu2020-8346, 2020.

EGU2020-4924 | Displays | HS2.2.1

A practical, objective, robust technique to directly estimate time of concentration

Giulia Giani, Miguel Angel Rico-Ramirez, and Ross Woods

Time of concentration is one of the key time variables in hydrology and it is essential for hydrograph design and hydrological modelling. Uncertainty in its estimation can cause errors in peak discharge rate and timing of flood events.

A unique recognized definition and methodology for its estimate is lacking and the multiple definitions and estimation procedures available in literature can give numerical prediction which can differ by up to 500% (Grimaldi et al., 2012). This result is not surprising given the high subjectivity of the traditionally used method to directly estimate time of concentration, also used for the calibration of the widely applied empirical formulae.

Given the importance of this time parameter in hydrology and the lack of a recognized and easily reproducible procedure for its estimate, here we propose a practical, objective, robust methodology to directly estimate time of concentration from rainfall and streamflow observations only. It’s a timeseries analysis technique used already in the Economics field (Kristoufek, 2014), that have been adapted to estimate time of concentration.

Compared to the traditionally used method, which is event based and requires hyetograph and hydrograph separation, the proposed methodology is designed to find the time delay from the original continuous timeseries but can also be applied to individual events by creating a timeseries of copies of the same event.

In the first place, the median of time of concentration distribution with the proposed methodology has been evaluated against the one with the traditionally used one in 79 catchments across the UK, showing that in most of the sites estimates coming from the two methods are very similar (correlation value of 0.82). This means that it is possible to avoid the separation of the hydrograph, required by the traditionally used method, which is a highly subjective procedure.

Secondly, we show that, when considering the proposed methodology only, for each catchment the time of concentration estimate using the continuous timeseries has a small discrepancy compared to the median of the time of concentration distribution of the single events estimates (correlation value of 0.94). Therefore, rainfall-streamflow events selection is not necessary and a reliable estimate of time of concentration can be obtained by applying the proposed methodology on the continuous timeseries at once, reducing the computational cost.

The proposed timeseries analysis technique is easy to automate, reproducible and make possible to objectively compare time of concentration estimates in all the catchments where the resolution of rainfall and streamflow timeseries is high enough to capture the runoff process.

How to cite: Giani, G., Rico-Ramirez, M. A., and Woods, R.: A practical, objective, robust technique to directly estimate time of concentration, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-4924, https://doi.org/10.5194/egusphere-egu2020-4924, 2020.

EGU2020-13723 | Displays | HS2.2.1

Non-Parametric Bayesian Networks for Hydrological Studies

Elisa Ragno, Markus Hrachowitz, and Oswaldo Morales-Nápoles

Non-Parametric Bayesian Networks (NPBNs) are graphical tools for statistical inference when new information become available. They have been widely used for reliability analysis and risk assessment. However, few hydrological applications can be found in the literature. Consequently, we explore the potential of NPBNs for maximum river discharge estimation by investigating a number of catchments with contrasting climate across the United States. Different networks schematizing river discharge generation processes at the catchment scale are built and analysed. Hydro-meteorological forcings and catchment's attributes are retrieved from Catchment Attributes for Large-Sample Studies (CAMELS). We highlight the benefits but also the challenges encountered in the application of NPBNs for river discharge estimation. Finally, we provide insights on how to overcome some of the difficulties met.

How to cite: Ragno, E., Hrachowitz, M., and Morales-Nápoles, O.: Non-Parametric Bayesian Networks for Hydrological Studies, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-13723, https://doi.org/10.5194/egusphere-egu2020-13723, 2020.

EGU2020-12074 | Displays | HS2.2.1

Numerical behavior of a coupled surface/subsurface, flow/transport hydrological model

Claudio Paniconi and Claire Lauvernet

Integrated surface/subsurface hydrological models (ISSHMs) are by now widely used in research and applied hydrology. While most studies have so far focused on water flow alone, ISSHMs that include also solute transport are beginning to get attention (e.g., Scudeler et al., 2016, doi:10.5194/hess-20-4061-2016; Gatel et al., 2019, doi:10.1016/j.envsoft.2018.12.006). Numerous numerical challenges are associated with these "doubly coupled" systems: correct treatment of surface boundary conditions and other mass and flux exchange terms; appropriate time stepping schemes across subsystems that are characterized by different dynamic time scales and often also widely different numerical discretization approaches; performance assessments that can be highly sensitive to the response variables of interest; and so on. We will illustrate some of these challenges via test case simulations of an experimental hillslope using the CATHY (CATchment HYdrology) model (Camporese et al., 2010, doi:10.1029/2008WR007536; Weill et al., 2011, doi:10.1016/j.advwatres.2010.10.001). The boundary condition-based coupling strategy used in this model (Putti and Paniconi, 2004, doi:10.1016/S0167-5648(04)80152-7) has been shown to be mathematically rigorous and mass-conservative for the flow model (Sochala et al., 2009, doi:10.1016/j.cma.2009.02.024). The convergence-based time step adaptation strategy used for the nonlinear flow equation (Paniconi and Putti, 1994, doi:10.1029/94WR02046) is likewise thoroughly tested (e.g., D'Haese et al., 2007, doi:10.1002/fld.1369) and widely used. Nonetheless, these schemes, and analogous approaches used in other ISSHMs, need to be adapted and thoroughly tested for coupled systems that include solute transport.

How to cite: Paniconi, C. and Lauvernet, C.: Numerical behavior of a coupled surface/subsurface, flow/transport hydrological model, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-12074, https://doi.org/10.5194/egusphere-egu2020-12074, 2020.

EGU2020-18909 | Displays | HS2.2.1

Can a hydrological model be efficient and robust at the same time?

Paul Royer-Gaspard, Vazken Andréassian, and Guillaume Thirel

It has been shown in various experiments that many conceptual rainfall-runoff models experience difficulties to simulate annual or longer-term variations of the streamflow (e.g. Coron et al., 2014). Whether this problem is inherent to the structure of the model in question or could be solved by a change of the calibration procedure is still a matter of debate: for example, the work of Coron (2013) tended to show that no parameter set able to solve the issue can be found, while Fowler et al. (2018) argued that such parameter sets exist, and should be identifiable by a change of objective function.

The aim of this study is to explore further the existence of such a parameter set in the case of the GR4J model (Perrin et al., 2003). Parameters sets were in particular tested against their ability to provide efficient (i.e. with good performance) and robust (i.e. transposable in time) discharge simulations over three flow ranges (low, mean and high flows). To this purpose, a large number of parameters sets of GR4J were sampled in 545 French and Australian catchments. The obtained performances were confronted to those obtained with automatic calibration with a range of objective functions focusing on diverse streamflow ranges.

Because of our large catchment set, we were able to identify a variety of cases: catchments for which highly robust parameter sets exist, catchments for which relatively robust parameter sets exist, and catchments for which no robust parameter sets can be found. Compared to the best sampled parameters sets, those derived through automatic calibration often yielded poorer performances regarding at the same time efficiency and robustness of the discharge simulations over the three flow ranges. We discuss the link between model failures and catchments characteristics, as well as the ability of the GR4J model to adequately simulate streamflow on different timescales and flow regimes.

How to cite: Royer-Gaspard, P., Andréassian, V., and Thirel, G.: Can a hydrological model be efficient and robust at the same time?, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-18909, https://doi.org/10.5194/egusphere-egu2020-18909, 2020.

EGU2020-13562 | Displays | HS2.2.1

Towards Conditional Parameter Estimation for Automatic Model Structure Identification: Using Mixed-Integer Calibration for Model Development

Diana Spieler, Juliane Mai, Bryan Tolson, James Craig, and Niels Schütze

A recently introduced framework for Automatic Model Structure Identification (AMSI) allows to simultaneously optimize model structure choices (integer decision variables) and parameter values (continuous decision variables) in hydrologic modelling. By combining the mixed-integer optimization algorithm DDS and the flexible hydrologic modelling framework RAVEN, AMSI is able to test a vast number of model structure and parameter combinations in order to identify the most suitable model structure for representing the rainfall runoff behavior of a catchment. The model structure and all potentially active model parameters are calibrated simultaneously. This causes a certain degree of inefficiency during the calibration process, as variables might be perturbed that are not currently relevant for the tested model structure. In order to avoid this, we propose an adaption of the current DDS algorithm allowing for conditional parameter estimation. Parameters will only be perturbed during the calibration process if they are relevant for the model structure that is currently tested. The conditional parameter estimation setup will be compared to the standard DDS algorithm for multiple AMSI test cases. We will show if and how conditional parameter estimation increases the efficiency of AMSI.

How to cite: Spieler, D., Mai, J., Tolson, B., Craig, J., and Schütze, N.: Towards Conditional Parameter Estimation for Automatic Model Structure Identification: Using Mixed-Integer Calibration for Model Development, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-13562, https://doi.org/10.5194/egusphere-egu2020-13562, 2020.

EGU2020-7416 | Displays | HS2.2.1

Diagnostic of a regional distributed hydrological model through hydrological signatures

Flora Branger, Ivan Horner, Jean Marçais, Yvan Caballero, and Isabelle Braud

Distributed models are useful tools for the assessment of water resources in a context of global change. However, due to the high spatial heterogeneity of the corresponding catchments, these models end up being quite complex with a high number of parameters. In particular, it is not easy to obtain good performances and physically sounded parameter values at all points in the catchment. In order to complement the traditional evaluation approach based on performance criteria, we developed a diagnostic approach based on hydrological signatures. A set of hydrological signatures based on precipitation and runoff data was defined and applied to a regional model of the Rhône basin (100 000 km2) in France. The comparison of simulated and observed signatures for 45 contrasted sub-basins of various sizes, climates, geologies and land uses, show that performance and ability to reproduce signatures are not always correlated. The analysis of signature results, combined with additional hydrogeology expertise, provided directions to improve the model parameterization, especially in the groundwater compartment. The study also provided feedback on the degree of information contained in the signatures and allows us to make recommendations for future studies.

How to cite: Branger, F., Horner, I., Marçais, J., Caballero, Y., and Braud, I.: Diagnostic of a regional distributed hydrological model through hydrological signatures, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-7416, https://doi.org/10.5194/egusphere-egu2020-7416, 2020.

EGU2020-1792 | Displays | HS2.2.1

A framework for visualizing the convergence performance of global optimization algorithms for hydrological models

Tian Lan, Kairong Lin, Chong-Yu Xu, and Xiaohong Chen

The convergence performance of global optimization algorithms determines the reliability of the optimized parameter set of hydrological models, thereby affecting the prediction accuracy. This study applies advanced data analysis and visualization techniques to design a novel framework for characterizing and visualizing the convergence behavior of the optimization algorithms when used for the parameter calibration of hydrological models. First, we utilize violin plots to assess the convergence levels and speeds in individual parameter spaces (ECP-VP). The density distributions of violin plots match the possible properties of fitness landscapes. Then, the parallel coordinates techniques are used to simulate the dynamic convergence behavior and assess the convergence performance in multi-parameter space (ECP-PC). Furthermore, the possible mechanism for the effect of linear or nonlinear relationships between the parameters on the convergence performance is investigated using the maximal information coefficient (MIC) and the Pearson correlation coefficient (Pearson r). Finally, the effect of the parameter sensitivity on the convergence performance is analyzed. The proposed framework is applied in multi-period and multi-basin dynamic conditions as case studies. The results showed that the ECP-VP and ECP-PC techniques were well suited for the evaluation of the convergence performance of global optimization algorithms for hydrological models. The evaluation results provided valuable information on determining the reliability of the final optima, as well as the dominant response modes of hydrological models. It is also demonstrated that the convergence levels and speeds in pairwise parameter spaces depend on the linear correlations but not on the nonlinear correlation between the parameters. Additionally, there is no significant relationship between the sensitivity of the parameters and their convergence performance.

How to cite: Lan, T., Lin, K., Xu, C.-Y., and Chen, X.: A framework for visualizing the convergence performance of global optimization algorithms for hydrological models, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-1792, https://doi.org/10.5194/egusphere-egu2020-1792, 2020.

EGU2020-8552 | Displays | HS2.2.1

Transferability of monthly water balance models under changing climate conditions in an arid catchment

Zana Topalovic, Andrijana Todorovic, and Jasna Plavsic

Assessment of climate change impact on water resources is often based on hydrologic projections developed using monthly water balance models (MWBMs) forced by climate projections. These models are calibrated against historical data but are expected to provide accurate flow simulations under changing climate conditions. However, an evaluation of these models’ performance is needed to explore their applicability under changing climate conditions, assess uncertainties and eventually indicate model components that should be improved. This should be done in a comprehensive evaluation framework specifically tailored to evaluate applicability of MWBMs in changing climatic conditions.

 

In this study, we evaluated performance of four MWBMs (abcd, Budyko, GR2M and WASMOD) used for hydrologic simulations in the arid Wimmera River catchment in Australia. This catchment is selected as a challenge for model application because it was affected by the Millennium drought, characterised by a decrease in precipitation and a dramatic drop in runoff. The model evaluation within the proposed framework starts with dividing the complete record period into five non-overlapping sub-periods, calibration and cross-validation (i.e., transfers) of the models. The Kling-Gupta efficiency coefficient is used for the calibration in each sub-period. Consistency in model performance, parameter estimates and simulated water balance components across the sub-periods is analysed. Model performance is quantified with statistical performance measures and errors in hydrological signatures. Because the relatively short monthly hydrologic series can lead to biased numerical performance indicators, the framework also includes subjective assessment of model performance and transferability. 

 

The results show that model transfer between climatically contrasted sub-periods affect all statistical measures of model performance and some hydrologic signatures: standard deviation of flows, high flow percentile and percentage of zero flows. While some signatures are reproduced well in all transfers (baseflow index, lag 1 and lag 12 autocorrelations), suggesting their low informativeness about MWBM performance, many signatures are consistently poorly reproduced, even in the calibrations (seasonal distribution, most flow percentiles, streamflow elasticity). This means that good model performance in terms of statistical measures does not imply good performance in terms of hydrologic signatures, probably because the models are not conditioned to reproduce them. Generally, the greatest drop in performance of all the models is obtained in transfers to the driest period, although abcd and Budyko slightly outperformed GR2M and WASMOD. Subjective assessment of model performance largely corresponds to the numerical indicators.

 

Simulated water balance components, especially soil and groundwater storages and baseflow, significantly vary across the simulation periods. These results suggest that the model components and the parameters that control them are sensitive to the calibration period. Therefore, improved model conceptualisations (particularly partitioning of fast and slow runoff components) and enhanced calibration strategies that put more emphasis on parameters related to slow runoff are needed. More robust MWBM structures or calibration strategies should advance transferability of MWBMs, which is a prerequisite for effective water resources management under changing climate conditions.

How to cite: Topalovic, Z., Todorovic, A., and Plavsic, J.: Transferability of monthly water balance models under changing climate conditions in an arid catchment, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-8552, https://doi.org/10.5194/egusphere-egu2020-8552, 2020.

EGU2020-792 | Displays | HS2.2.1

Improving hydrological model performance by incorporating dynamic variability of parameters

Lakshmi Girija and Sudheer Kulamullaparambathu

Extensive research is being carried out in developing new calibration procedures for improving the efficacy of hydrologic models. Considering the simulation period into separate wet and dry periods, and performing discrete calibration on each of them has resulted in improvement in model performance, especially during dry periods. In this procedure, it is envisaged that by splitting the time period into wet and dry, the temporal variability of soil moisture, which play a major role in maintaining the water balance of the catchment, is accounted. The discretely calibrated data is then recombined to form the entire time series. However, while recombining the discretely calibrated time periods, the physics of the hydrological processes, at the time of transition from one period to the other, may show abrupt variations. In addition, the short spells of wetness and dryness within this partitioned period, which influences the soil saturation, may not get effectively simulated. This study proposes division of simulation period into wet and dry spells considering the state of saturation of the watershed. This is achieved by clustering the time series of the data using the antecedent precipitation and the soil moisture conditions. A supervised Gustafson-Kessel clustering technique is employed for the same. Subsequently, a relationship between the precipitation, the daily change in soil moisture and a selected model parameter is established for all the cluster transitions and incorporated into the model structure. The proposed methodology is tested using a grid based model with six parameters, on Riesel watershed, Texas, USA. The results indicate that clusters formed are unique, with no fixed duration and no repetitive patterns across the entire simulation period. For preliminary analysis, only one parameter is dynamically varied depending on the incoming rainfall. The performance of the refined model (NSE = 0.85) over the conventional static parameter model (NSE = 0.83), though not significant, indicate that better process representation can aid in improving model simulations. It is noted that this method eliminates the abrupt variation of soil moisture across the wet and dry periods, as the simulation is continuous.

How to cite: Girija, L. and Kulamullaparambathu, S.: Improving hydrological model performance by incorporating dynamic variability of parameters, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-792, https://doi.org/10.5194/egusphere-egu2020-792, 2020.

EGU2020-13674 | Displays | HS2.2.1

Using a multi objective framework for improved calibration and spatial interpolation in hydrological models of the Berg river catchment, South Africa

Andrew Watson, Jodie Miller, Sven Kralisch, Annika Künne, and Manfred Fink

As understanding river flow regime dynamics is important for future management and conservation of global water resources, the use of hydrological models in ungauged rivers systems has become increasingly common. As the effectiveness of hydrological models to replicate streamflow is limited by the spatial and temporal density of climate stations, it becomes necessary to understand the climate representation of the model at various timesteps. As climate stations are often most dense near cities at low altitude, the importance of having enough stations at different elevation bands impacts the effectiveness of the hydrological model to replicate the sub-basin flow contribution. The use of multi-objective criteria to understand model performance at gauged sub-basins is important during model parameter transfer to ungauged sections. During this study the distributed J2000 rainfall/runoff model was used to understand the impact that climate station density has on model regionalisation and the simulation of hydrological flow components. Furthermore, a station importance factor was used to identify the models station reliance, the maximum station distance for effective hydrological simulation and the relative importance of flow from different sub-basins at the catchment outlet. The rainfall/runoff model was calibrated and validated using multi-objective criteria namely; Nash-Sutcliffe-Efficiency (E1 and E2), Percent Bias (PBIAS) and Kling-Gupta-Efficiency (KGE) coefficients for two gauges, located on the main stem of the river system, to determine a global model parameter dataset which can be used for the model sub-basins. The approach was applied to the Berg River, an inland catchment (7700 km2) located in the Western Cape province of South Africa. While the Berg River is an important agricultural area which is dominated by irrigation, it is also the source of large-scale inter-basin transfers to the metropolitan city of Cape Town. The Western Cape has recently (2012-2017) been subject to a crippling drought which had devastating impacts on agricultural production, as well as inter-basin transfers to the city of Cape Town. The results from the hydrological model showed that for precipitation spatial representation, a station density of 1/20 km2 as well as good mid-altitude (200-300 masl) coverage resulted in good hydrological modelling performance. For the simulation of evaporation, the spatial density of measurements impacted the estimation of potential evaporation, but simulated soil-moisture was the main control and station density did not affect the model results. This study highlights the importance of ensuring that precipitation station coverage is sufficient for effective hydrological simulations from sub-basins, with recommendations of both spatial coverage and elevational representation being provided for semi-arid Southern African conditions. The spatial accounting of micro-climatic variability goes some distance to ensure representative sub-basin flow contributions, improving the ability of hydrological models to replicate river flow regimes in semi-arid heterogenous catchments.

How to cite: Watson, A., Miller, J., Kralisch, S., Künne, A., and Fink, M.: Using a multi objective framework for improved calibration and spatial interpolation in hydrological models of the Berg river catchment, South Africa , EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-13674, https://doi.org/10.5194/egusphere-egu2020-13674, 2020.

Hydrologic modelling is an indispensable tool for simulation of river basin processes in water resources planning and management. Hydrologic models are used to understand dynamic interactions between climate and river basin hydrology. Model calibration, validation, parameter sensitivity and uncertainty analysis are essential prior to the application of hydrologic models. A large catchment with high spatial variability and heterogeneity can be modeled realistically when calibration is done at multiple locations, for multiple hydrologic variables like streamflow, soil moisture, sediment flow, evapotranspiration, etc. This ensures maximum utilization of field measurements of the hydrological variables, reduces the uncertainty in parameter identification and highlights the areas that need greater calibration effort. In the present study, hydrologic model simulations are run for the Mahanadi river basin in India using SWAT (Soil and Water Assessment Tool) and model calibration, uncertainty analysis, sensitivity analysis and validation are performed using SUFI-2 optimization algorithm in SWAT-CUP (SWAT Calibration and Uncertainty Programs). Entire Mahanadi basin is calibrated for several variables like streamflow, soil moisture, sediment load and evapotranspiration at various locations. The spatial heterogeneity of the catchment is taken into account in model calibration by choosing appropriate ranges of different parameters for each sub basin based on the soil types, slope classes and land use land cover present in the sub basins. When multi-site multi-variable calibration is carried out, serial calibration for individual variables and locations gives different result when compared with the simultaneous calibration for all variables and locations. In this study, a comparison of serial calibration for individual hydrologic variables and calibration sites versus simultaneous calibration for all hydrologic variables and calibration sites is made. Various performance measures like Nash-Sutcliffe efficiency (NSE), percent bias, coefficient of determination, modified NSE, etc. are used to quantify the model fit between the observed and the simulated values of various variables. The choice of performance measure affects the calibration solution, and depends on the calibration variables for which observed data is available. The performances of the fitted parameters are conditional with respect to the calibration variables and the choice of the performance measure. The present study talks about the suitability of the performance measure to different hydrologic variables like streamflow, sediment load, soil moisture, etc. The model simulation results for the Mahanadi river basin are compared with the observed values of hydrologic variables using different performance measures for calibration and validation of the model. The results show that model performance is enhanced when it is calibrated at multiple locations, for multiple variables, by taking the spatial variability of parameters across various sub-basins into account. This study explores the suitability of different performance measures for different hydrologic variables and compares the serial and simultaneous calibration for multiple hydrologic variables at multiple locations.

How to cite: Srivastava, S. and Dasika, N. K.: Multi-site multi-variable hydrologic model development for spatially heterogeneous river basins to achieve realistic basin modelling, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-5044, https://doi.org/10.5194/egusphere-egu2020-5044, 2020.

EGU2020-993 | Displays | HS2.2.1

The influence of the spatial distribution of agricultural conservation practices on hydrological balance variables in a small basin

Nina Noreika, Tomas Dostal, Tailin Li, David Zumr, and Josef Krasa

SWAT is perhaps the most widely-used basin-scale hydrological model discussed in modern literature. SWAT is typically used to model large basins (100+ km2) and has even successfully modeled basins at continental scales. Regardless of the typical scale that SWAT is used, SWAT has been shown to adequately model various hydrological processes at smaller scales, but this application is much less common in the literature.  The aim of this study is to utilize SWAT+ in a small (<1 km2) agricultural basin (Nucice) approximately 30 kilometers southeast of Prague, Czechia to determine the effects of various spatial distribution patterns of agricultural conservation practices (no/reduced tillage, crop residues, cover crops, etc.) and their respective impacts on projected runoff, soil water retention, and evapotranspiration.

We were able to successfully calibrate our SWAT+ model for the Nucice experimental catchment from 2014 through part of 2018 using discharge data and estimating ET via remote sensing. After successful calibration, we implemented 4 scenarios to analyze the effects of implementing agricultural conservation practices: 25% continuous in upper 50% of basin, 25% fragmented in upper 50% of basin, 25% continuous in lower 50% of basin, and 25% fragmented in lower 50% of basin.

The adaptation pattern of agricultural conservation practices has significant and disproportionate effects on various hydrological balance parameters. Since it is rare that a single farmer manages an entire basin, this study shows that widespread adaptation of agricultural practices is necessary to maximize water conservation within a landscape. We intend to upscale this study (100+ km2 basins) and to compare basins across multiple climates to determine if these effects are universal.

This research has been supported by project H2020 No. 773903 Shui, focused on water scarcity in European and Chinese cropping systems.

How to cite: Noreika, N., Dostal, T., Li, T., Zumr, D., and Krasa, J.: The influence of the spatial distribution of agricultural conservation practices on hydrological balance variables in a small basin, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-993, https://doi.org/10.5194/egusphere-egu2020-993, 2020.

EGU2020-21490 | Displays | HS2.2.1

Assessment of the performance of Soil Water Assessment Tool (SWAT) model for a small agricultural catchment in Austria

Francis Kilundu Musyoka, Andreas Klik, and Peter Strauss

Hydrological models enable comprehensive examination, understanding and quantification of hydrological processes in catchments under the influence of different characteristics. The Soil and Water Assessment Tool (SWAT) has the ability to predict the impact of land management practices on water, sediment and agricultural chemical yield in such catchments.

The objective of this study is to apply the SWAT model on a small agricultural watershed, calibrate and validate it with measured flow, sediment and crop yield data. The model is set up for the HOAL catchment in Petzenkirchen, Lower Austria. The catchment has an area of 66 hectares. The climate is humid with mean annual temperatures of around 10°C, and annual precipitation of around 800 mm. Soils include Cambisols and Planosols with medium to poor infiltration capacities. Gleysols occur close to the stream. At present, 87% of the catchment area is arable land, 5% is used as pasture, 6% is forested and 2% is paved. The agricultural activities mainly involve wheat based crop rotation including winter wheat, winter barley, sweet and silage corn and canola. The catchment is divided into 37 fields and for each field exact information about tillage date and type of implement used, date of planting and harvest, date and amount of fertilization and plant protection are available. This information is incorporated in the model during set up. The procedures of model set up, sensitivity analysis, calibration and validation are outlined. A Sequential Uncertainty Fitting (SUFI-2) procedure within SWAT-CUP is used to auto-calibrate and validate the model. The model calibration (2012-2014) and validation (2015-2017) is based on the observed daily discharge and daily sediment concentration at the watershed outlet. Event based observations of runoff and sediment yield from two sub-watersheds are available as well as measured soil water contents at 30 points and crop yield data from different fields. Stream flow and sediment calibration are performed at the watershed outlet as well as at sub watershed level. Results of the SWAT model capability to predict flow, sediment and crop yield as well as soil water contents in the small watersheds will be presented.

How to cite: Musyoka, F. K., Klik, A., and Strauss, P.: Assessment of the performance of Soil Water Assessment Tool (SWAT) model for a small agricultural catchment in Austria, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-21490, https://doi.org/10.5194/egusphere-egu2020-21490, 2020.

EGU2020-541 | Displays | HS2.2.1

Impacts of LULC and climate change on streamflow in Netravati basin, Karnataka, India

Dinu Maria Jose and Gowdagere Siddaramaiah Dwarakish

Human activities and climate affect the hydrology of a basin. The effect of Land Use Land Cover (LULC) change and climate change on streamflow are basin specific. In this study, an attempt has been made to evaluate the effects of LULC and climate change on streamflow in the Netravathi basin, Karnataka, India. The SWAT model, which reasonably simulates the streamflow of a basin, is used for this study. The analysis was done from the year 1990 to 2018. The watershed is delineated by using ALOS PALSAR DEM. Rainfall and temperature obtained from IMD are used as the climate variables. LULC maps were prepared using Landsat images of 1990 and 2018 in order to assess the LULC changes in the basin. The results showed that the spatial extent of the LULC classes of built-up (3.82%–6.51%), water bodies (0.76%–0.99%), and agriculture (11.96%–17.89%) increased, whereas that of forest (66.56%–51.7%), fallow (3.82%–6.13%), and barren land (13.07%–16.76%) decreased from 1990 to 2018. The streamflow increased steadily (5.02%) with changes in LULC from 1990 to 2018. The results indicate that LULC changes in urbanisation and agricultural intensification have contributed to the increase in runoff, in the catchment during this period. Thus, hydrological modelling integrating climate change and LULC can be used as an effective tool in estimating streamflow of the basin.

How to cite: Jose, D. M. and Dwarakish, G. S.: Impacts of LULC and climate change on streamflow in Netravati basin, Karnataka, India, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-541, https://doi.org/10.5194/egusphere-egu2020-541, 2020.

The intensification of climate change and human activities can lead to non-stationarity of hydrological model parameters, which in turn affects the correctness of model simulation results. Previous studies mainly focus on impacts of climate change, while catchment hydrological responses to human activities require detailed investigation for sustainable water management. This study evaluates anthropogenic impacts on soil water storage capacity of the upper Yangtze River Basin by representing hydrological parameters as functions of human activity indicators. The Xinanjiang (XAJ) model is used since its parameter WM accounts for soil water storage capacity. In this study, time-variations of WM are identified by the split-sample calibration based on dynamic programming (SSC-DP). The variations are further related to ten indicators of human activities from five aspects: population, gross domestic product, farming, irrigation and reservoir construction. Then, the proposed WM functional form is selected by comparing the performance of a set of parameter functions of the identified human activity indicators during the validation period. The study shows that WM increases in 1976-2000, while a relatively high relationship is detected between WM and some indicators such as agricultural acreage, population and reservoir construction. It is further demonstrated that agricultural population has the greatest impact on soil water storage capacity and its linear functional form for WM is validated to be effective in 2001-2010 with best streamflow simulation, especially for low streamflow. These results can help understand the hydrological response to the increasing human development and contribute to adaptive development strategies for future water resource management.

How to cite: Zhang, X., Liu, P., and Xu, C.-Y.: The hydrological response of soil water storage capacity to human activities: A case study in the upper Yangtze River Basin, China, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-5142, https://doi.org/10.5194/egusphere-egu2020-5142, 2020.

With the global climate change and the rapid expansion of urban land use, urban storms and floods have occurred frequently. The state has gradually attached importance to the unified construction of low-impact development facilities (LID) and underground integrated pipe corridors (GL), which makes sponge city both beautiful and practical. In order to study the urban hydrological response of the combination between LID and underground integrated pip corridors (LID_GL), the Yangmei River Basin, a pilot area of ​​Guangzhou's integrated pipe corridors, was taken as an example to evaluate and compare the hydrological response of traditional development, GL, LID, GL_LID scenarios. The results show that:

  • (1) The traditional development scenario is verified by the measured rainfall of “2018.06.08”. The simulation results are consistent with the areas where are liable to waterlogging under the actual circumstance, which proves that the SWMM model is suitable for the hydrological response evaluation of LID_GL scenario in the Yangmei River Basin.
  • (2) The SUSTAIN model can realize the optimized layout of LID, but the simulation accuracy needs to be improved. On the contrary, the SWMM model cannot realize the LID optimized layout, but the simulation accuracy of urban hydrological response is high. To Combine their advantages, the LID optimized layout schemes calculated by SUSTAIN model are input into SWMM model for hydrological simulation. The results show that this method can avoid the situation that the evaluation results are irrational due to improper layout of LID.
  • (3) The overflow reduction in the LID_GL scenario is best, which can exceed 60% under high-return-period rainfall conditions. Its peak outlet flow is lower than GL scenario and the peak appearance time is also delayed.

The above research results can provide reference and theoretical support for the unified construction of LID and underground integrated pip corridors (LID_GL) in the future.

How to cite: Li, S., Wang, Z., and Liu, Q.: The hydrological response of the combination between LID and underground integrated pip corridors based on SUSTAIN, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-3199, https://doi.org/10.5194/egusphere-egu2020-3199, 2020.

EGU2020-2065 | Displays | HS2.2.1

Reconstructing floods in small-medium scale data-scarce catchments using field interview data and hydrodynamic modelling

Mark Bawa Malgwi, Jorge Alberto Ramirez, Andreas Zischg, Markus Zimmermann, Stefan Schürmann, and Margreth Keiler

We develop a technique for reconstructing floods in small-scale data scarce regions using field interview data and hydro-dynamic modelling. The field interview data consist of flood depths and duration data collected from 300 buildings from a flood event in 2017 in Suleja/Tafa area, Nigeria. The flood event resulted from an overflow of water from five river reaches. The hydrodynamic model utilized, called CAESER LisFLOOD, is an integration of a landscape evolution model (CAESER) and a hydraulic model (LisFLOOD-FP). We employ three steps to reconstruct the 2017 Suleja/Tafa flood event. Firstly, we use a linearly increasing hydrograph to; (a) calibrate Manning’s coefficient and (b) determine optimal peak discharge on each reach. This was carried out by minimizing the Root Mean Square Error (RMSE) between the distributed observed flood depths and the simulated flood depths. Secondly, we use synthetic hydrographs with durations between 6, 12, 18, 20, 24 hours, having peak discharge (extracted from the previous step), to simulate flows on all upstream reaches. Using collected flood duration data, we minimized RMSE between distributed observed flood duration and simulated flood duration to determine optimal flow durations on each upstream reach. In the last step, utilizing peak discharge and flow duration for all upstream reaches, we carried out multiple spatial and temporal iterations to match downstream peak discharge. Thereafter, we use determined upstream hydrographs with their relative catchment response timing to simulate the entire river network. Minimum RMSE computed for the entire river network was between ±15 cm of many current studies that use distributed observed data to calibrate flood models. The method developed in this study is useful for simulating floods in regions where data such as high resolution DEMs, river bathymetry and river discharge are limited. In addition, the study extends current knowledge, on utilizing distributed flood data to determine peak discharge, from a single to multiple river networks.

How to cite: Malgwi, M. B., Ramirez, J. A., Zischg, A., Zimmermann, M., Schürmann, S., and Keiler, M.: Reconstructing floods in small-medium scale data-scarce catchments using field interview data and hydrodynamic modelling, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-2065, https://doi.org/10.5194/egusphere-egu2020-2065, 2020.

Fluvial flood events are a major threat to people and infrastructure. To compute flood risk estimates, modelling cascades are often applied. Therein, flood hazard is driven by hydrologic or river routing and floodplain flow processes. As such, model selection within such a cascade can determine how well some of these processes can be simulated. Depending on the selection made, obtained flood maps can vary and, in turn, can have major implications for the analysis of how many people, buildings, economic values and so forth is at risk. Understanding the role of model selection in the flood risk modelling process is thus of great importance.

By means of GLOFRIM 2.0, we coupled the global hydrologic model PCR-GLOBWB with the hydrodynamic models CaMa-Flood and LISFLOOD-FP for the delta region of the Ganges-Brahmaputra basin. Applying the model-coupling framework GLOFRIM facilitates forcing various models with identical boundary conditions and thus transparent and objective inter-comparison of flood models.

While replacing the kinematic wave approximation of the hydrologic model with the local inertia equation of hydrodynamic models does not yield better discharge estimates in the Ganges basin, flood maps obtained with LISFLOOD-FP improved representation of observed flood extent. Compared to downscaled products of PCR-GLOBWB and CaMa-Flood, the critical success index increases by around 50 %.

Combining the obtained flood maps with actual exposure maps gives then a first-order estimate how the selection for one specific model set-ups translates into varying flood risk estimates. The research thus shows how those model selections, deliberately made or not, are an important driver of simulated flood risk. As such, it is detrimental that the various specifics of a model are known to facilitate the optimal model selection for objective-specific modelling requirements.

How to cite: Hoch, J., Eilander, D., and Ikeuchi, H.: How model selection can determine flood risk estimates – a case study in the Ganges basin using the GLOFRIM framework, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-11086, https://doi.org/10.5194/egusphere-egu2020-11086, 2020.

EGU2020-21016 | Displays | HS2.2.1

Long-term hydrological and hydrodynamic modeling of a complex Ramsar site using HEC-RAS 5.0.7 2D – The Taim Wetland

Bibiana Peruzzo Bule, Rutinéia Tassi, and Daniel Gustavo Allasia Piccilli

Wetlands are ecosystems recognized as one of the most valuable natural resources in the world. Although this importance, several wetlands around the world have lost areas due to anthropic threats. One example of a wetland with international importance is the Taim Wetland. This Ramsar Site number 2298, is a fresh-water wetland with 330 km2 located in the Southern part of Brazil, close to the border with Uruguay. The primary threat to this wetland is related to water demand conflicts on its watershed. Extensive rice fields occur around Taim Wetland and large yearly volumes of water from its main tributary Mangueira Lake are withdrawn, leading to changes in the hydrodynamics within the wetland. Thus, by one side, there is the regional economic dependence of rice cultivation and, on the other hand, conditions related to water availability are vital for maintaining the ecosystem as a whole. Different human-made infrastructures also impact local hydrodynamics as road, gates, fauna tunnels, natural effects as backwater and climate factors. Due to its importance, the Taim Wetland has been the object of different studies aiming to evaluate strategies for an integrated water management policy, allowing it to reach both environmental and economic benefits. The local complexity leads to the need for applying hydrological-hydrodynamic models able to represent the behavior accurately. Paz, 2003 and Villanueva, 1997 already applied hydrological and 2D-hydrodynamic modeling in the area; however, in the light of information available at that time and computational constraints, these studies needed to adopt several simplifications. In this study, the 2D HEC-RAS 5.0.7 was used to represent the system based on new terrain information obtained from the combination of different sources such as satellite, drone images and local measurement allowing the acquisition of information such as flooding areas, velocities, and flow patterns. New insights of local features such as internal channels, lakes, dunes, road and vegetation such as emergent macrophytes permitted new understandings of hydrodynamics. Nevertheless, hydraulic structures as a set of gates and fauna tunnels were also included in the representation, allowing the analysis of different operational scenarios during the modeling. These results also provide critical information for the environmental evaluation of habitats and points towards better management policies.

How to cite: Peruzzo Bule, B., Tassi, R., and Allasia Piccilli, D. G.: Long-term hydrological and hydrodynamic modeling of a complex Ramsar site using HEC-RAS 5.0.7 2D – The Taim Wetland, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-21016, https://doi.org/10.5194/egusphere-egu2020-21016, 2020.

HS2.2.2 – Earth System Models and coupled atmosphere-hydrological simulations: model development, applications and coupled data assimilation

EGU2020-18135 | Displays | HS2.2.2

Towards an Effective and Scalable Hybrid Data Assimilation for Hydrogeophysical Applications

Hamid Moradkhani, Peyman Abbaszadeh, and Kayhan Gavahi

A number of studies have shown that multivariate data assimilation into the land surface models would improve model predictive skills. Soil moisture, streamflow and Evapotranspiration are among those environmental variables that greatly affect flood forecasting, drought monitoring/prediction, and agricultural production that collectively control the land and atmospheric system. However, land surface models most often do not provide accurate and reliable estimates of fluxes and storages and are subject to large uncertainties stemming from hydrometeorological forcing, model parameters, boundary or initial condition and model structure. Here, we present the state-of-the art data assimilation methods, covering the evolution of methods, discussing their pros and cons and introduce a novel approach that couples a deterministic four‐dimensional variational (4DVAR) assimilation method with an evolutionary ensemble filtering that together  significantly improve the estimation of storages and fluxes, hence better forecasting skill. The Evolutionalry Particle Filter with MCMC (EPFM) uses the Genetic Algorithm (GA) to effectively sample the particles to better represent the posterior distribution of model prognostic variables and parameters. This is followed by coupling EPFM and 4DVAR which results in a superior DA approach, the so-called Hybrid Ensemble and Variational Data Assimilation framework for Environmental systems (HEAVEN). The method explicitly accounts for model structural error during the assimilation process. The application of methods is presented for both flood and drought forecasting while utilizing the remotely sensed observations.

How to cite: Moradkhani, H., Abbaszadeh, P., and Gavahi, K.: Towards an Effective and Scalable Hybrid Data Assimilation for Hydrogeophysical Applications, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-18135, https://doi.org/10.5194/egusphere-egu2020-18135, 2020.

EGU2020-3024 | Displays | HS2.2.2

Data assimilation for a visco-elastic Earth deformation model

Reyko Schachtschneider, Jan Saynisch-Wagner, Meike Bagge, Volker Klemann, and Maik Thomas

We present a data assimilation algorithm for the time-domain spectral-finite element code VILMA. We consider a 1D earth structure and a prescribed  glaciation history ICE5G for the external mass load forcing. We use the Parallel Data Assimilation Framework (PDAF) to assimilate sea level data into the  model in order to obtain better estimates of the viscosity structure of mantle and lithosphere. For this purpose, we apply a particle filter in which an ensemble of models is propagated in time, starting shortly before the last glacial maximum. At epochs when observations are available, each particle's performance is estimated  and they are resampled based on their performance to form a new ensemble that better resembles the true viscosity distribution. In a proof of concept we  show that with this method it is possible to reconstruct a synthetic viscosity distribution from which synthetic data were constructed. In a second step,  paleo sea level data are used to infer an optimised 1D viscosity distribution.

How to cite: Schachtschneider, R., Saynisch-Wagner, J., Bagge, M., Klemann, V., and Thomas, M.: Data assimilation for a visco-elastic Earth deformation model, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-3024, https://doi.org/10.5194/egusphere-egu2020-3024, 2020.

The air-sea interface is one of the most physically active interfaces of the Earth's environments and significantly impacts the dynamics in both the atmosphere and ocean. In this study, we discuss the data assimilation of surface drifters, of which the dynamic motions are highly relevant to the instant change of both surface wind field and underlying ocean flow fields. We intend to take advantage of this relationship and improve the estimation of the model initialization in both ocean and coupled atmosphere-ocean systems.

The assimilation of position data from Lagrangian observing platforms is underdeveloped in operational applications because of two main challenges: 1) nonlinear growth of model and observation error in the Lagrangian trajectories, and 2) the high dimensionality of realistic models. In this study, we first propose an augemented-state Lagrangian data assimilation (LaDA) method that is based on the Local Ensemble Transform Kalman Filter (LETKF). The algorithm is tested with “identical twin” approach of Observing System Simulation Experiments (OSSEs) using the ocean model. Examinations on both of the eddy-permitting and the eddy-resolving Modular Ocean Model of the Geophysical Fluid Dynamics Laboratory (GFDL) are tested, which is intended to update the ocean states (T/S/U/V) at both the surface and at depth by directly assimilating the drifter locations. Results show that with a proper choice of localization radius, the LaDA can outperform conventional assimilation of surface in situ temperature and salinity measurements. The improvements are seen not only in the surface state estimate, but also throughout the ocean column to deep layer. The impacts of localization radius and model error in estimating accuracy of both fluid and drifter states are further investigated. In the second section, we investigate the LaDA within a Strongly Coupled Data Assimilation (SCDA) system using the simplified Modular Arbitrary-Order Ocean-Atmosphere Model (MAOOAM), a three-layer truncated quasi-geostrophic model. Results show that assimilating the surface drifter locations directly is capable of improving not only the ocean states but also the atmosphere states as well. We then compare it to the conventional approach to assimilate the approximated velocities instead of the direct drifter locations and it shows that the assimilating drifter locations outperforms the other approach.

How to cite: Sun, L.: Lagrangian Data Assimilation of Surface Drifters to Support Ocean and Coupled Model Initialization, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-10809, https://doi.org/10.5194/egusphere-egu2020-10809, 2020.

EGU2020-5023 | Displays | HS2.2.2

Weakly and strongly coupled data assimilation with the coupled ocean-atmosphere model AWI-CM

Qi Tang, Longjiang Mu, Dmitry Sidorenko, and Lars Nerger

In this study we compare the results of strongly coupled data assimilation (SCDA) and weakly coupled data assimilation (WCDA), and among the different WCDAs by analyzing the assimilation effect on the prediction of the ocean as well as the atmosphere variables. We have implemented the parallel data assimilation framework (PDAF, http://pdaf.awi.de) with the AWI climate model (AWI-CM), which couples the ocean model FESOM and the atmospheric model ECHAM. In the WCDA, the assimilation acts separately on each component in the coupled model and observations of one component only directly influence its own component. The other components can benefit from the DA through the model dynamics. The alternative to WCDA is SCDA, in which the atmosphere as well as the ocean variables are updated jointly using cross-covariances between the two components. Our current system allows both the SCDA and the WCDA. For the SCDA configuration, either the ocean observations (e.g., satellite sea surface temperature, profiles of temperature and salinity) or the atmosphere observations (e.g., air temperature, surface pressure) or both of them can be assimilated to update the ocean as well as the atmosphere variables. For the WCDA, it allows 1) assimilating only the ocean observations into the ocean state; 2) assimilating only the atmosphere observations into the atmosphere state; 3) assimilating both types of observations into the corresponding component models. The results are evaluated by comparing the estimated ocean and atmosphere variables with the observational data.

How to cite: Tang, Q., Mu, L., Sidorenko, D., and Nerger, L.: Weakly and strongly coupled data assimilation with the coupled ocean-atmosphere model AWI-CM, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-5023, https://doi.org/10.5194/egusphere-egu2020-5023, 2020.

EGU2020-15057 | Displays | HS2.2.2

Towards an ensemble-based assimilation of boundary-layer observations for soil moisture

Tobias Sebastian Finn, Gernot Geppert, and Felix Ament

The temporal and spatial development of the atmospheric boundary layer is coupled to soil conditions via latent and sensible heat flux. Information about soil conditions is following encoded in atmospheric screen-level observations. To infer the soil moisture, these observations are usually assimilated with a Simplified Extended Kalman Filter (SEKF). This data assimilation technique is simplified in comparison to Ensemble Kalman Filters (EnKF), which are often used for data assimilation in the atmosphere. To make full use of the interface between atmosphere and land, we want to use strongly-coupled data assimilation with a unified system. We will present which problems have to be solved within an EnKF framework to use it as unified data assimilation system. We initialized an observing system simulation experiment with the TerrSysMP system, where a limited area model for the atmosphere is coupled with the Community Land Model. Here, we assimilate the two-metre temperature with an EnKF to update the soil moisture for a dry time period. We use initial soil moisture and soil temperature perturbations as only method to create an ensemble.

We show a positive observation impact during daytime. The analysis and forecast are further improved compared to assimilation with a SEKF. During daytime, the atmosphere and soil are strongly coupled, while they are almost uncoupled during night-time. Following, we have a slightly negative observation impact during night-time. This negative impact is induced by sampling errors of the ensemble. The negative impact is further amplified in the transition time between night and day. We can attribute this amplification to horizontal heterogeneities and multiplicative ensemble inflation in soil. We can therefore say that the inflation is wrongly tuned for the soil during night-time, while it works for the atmosphere and during daytime. We hypothesize that these problems during night-time can be avoided by using additional models, like a time-dependent localization radius and inflation factor.

How to cite: Finn, T. S., Geppert, G., and Ament, F.: Towards an ensemble-based assimilation of boundary-layer observations for soil moisture, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-15057, https://doi.org/10.5194/egusphere-egu2020-15057, 2020.

EGU2020-17855 | Displays | HS2.2.2

High-resolution fully-coupled atmospheric–hydrological modeling: a cross-compartment regional water and energy cycle evaluation

Benjamin Fersch, Alfonso Senatore, Bianca Adler, Joël Arnault, Matthias Mauder, Katrin Schneider, Ingo Völksch, and Harald Kunstmann

The land surface and the atmospheric boundary layer are closely intertwined with respect to the exchange of water, trace gases and energy. Nonlinear feedback and scale dependent mechanisms are obvious by observations and theories. Modeling instead is often narrowed to single compartments of the terrestrial system or bound to traditional viewpoints of definite scientific disciplines. Coupled terrestrial hydrometeorological modeling systems attempt to overcome these limitations to achieve a better integration of the processes relevant for regional climate studies and local area weather prediction. We examine the ability of the hydrologically enhanced version of the Weather Research and Forecasting Model (WRF-Hydro) to reproduce the regional water cycle by means of a two-way coupled approach and assess the impact of hydrological coupling with respect to a traditional regional atmospheric model setting. It includes the observation-based calibration of the hydrological model component (offline WRF-Hydro) and a comparison of the classic WRF and the fully coupled WRF-Hydro models both with identical calibrated parameter settings for the land surface model (Noah-MP). The simulations are evaluated based on extensive observations at the pre-Alpine Terrestrial Environmental Observatory (TERENO Pre-Alpine) for the Ammer (600 km²) and Rott (55 km²) river catchments in southern Germany, covering a five month period (Jun–Oct 2016).

The sensitivity of 7 land surface parameters is tested using the Latin-Hypercube One-factor-At-a-Time (LH-OAT) method and 6 sensitive parameters are subsequently optimized for 6 different subcatchments, using the Model-Independent Parameter Estimation and Uncertainty Analysis software (PEST).

The calibration of the offline WRF-Hydro leads to Nash-Sutcliffe efficiencies between 0.56 and 0.64 and volumetric efficiencies between 0.46 and 0.81 for the six subcatchments. The comparison of classic WRF and fully coupled WRF-Hydro shows only tiny alterations for radiation and precipitation but considerable changes for moisture- and energy fluxes. By comparison with TERENO Pre-Alpine observations, the fully coupled model slightly outperforms the classic WRF with respect to evapotranspiration, sensible and ground heat flux, near surface mixing ratio, temperature, and boundary layer profiles of air temperature. The subcatchment-based water budgets show uniformly directed variations for evapotranspiration, infiltration excess and percolation whereas soil moisture and precipitation change randomly.

How to cite: Fersch, B., Senatore, A., Adler, B., Arnault, J., Mauder, M., Schneider, K., Völksch, I., and Kunstmann, H.: High-resolution fully-coupled atmospheric–hydrological modeling: a cross-compartment regional water and energy cycle evaluation, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-17855, https://doi.org/10.5194/egusphere-egu2020-17855, 2020.

EGU2020-10223 | Displays | HS2.2.2

Contribution of lateral terrestrial water flow to precipitation – A WRF-Hydro ensemble analysis and continental evaporation tagging for Europe

Joel Arnault, Benjamin Fersch, Thomas Rummler, Zhenyu Zhang, Jianhui Wei, Mayeul Quenum, Maximilian Graf, Patrick Laux, and Harald Kunstmann

Land-atmosphere feedback processes are key components of the Earth climate system. In general, it is questionable to which extend the state of the land surface feeds back to the state of the atmosphere. This question can be addressed with a coupled land surface – atmospheric model, and the realism of the simulated feedbacks can be evaluated with a model-to-observation comparison. This study investigates the particular case of the process chain linking lateral terrestrial water flow, soil moisture, surface evaporation and precipitation. The focus is on summer precipitation in the European region. The study period is set to four months in June-September 2008. The tool to conduct this study is the coupled atmospheric – hydrological model WRF-Hydro, which allows surface and subsurface water routing. For the setup of the atmospheric part, a horizontal grid of 700x500 grid points with a grid spacing of 5 km, that is covering an area of 3500 km x 2500 km, and 50 vertical levels up to 10 hPa is chosen. For the setup of the land water routing, a horizontal grid of 14000x10000 grid points with a grid spacing of 250 m and 4 soil layers down to 2 m depth is chosen. The employed model version includes a surface evaporation tagging procedure in order to quantify the fraction of European precipitation originating from evaporation from all over the European continent. The method consists of generating a set of WRF-Hydro simulations with and without land water routing by using random realizations of the stochastic kinetic energy backscatter scheme, and assess the impact of lateral terrestrial water flow on precipitation with the daily gridded observational dataset for precipitation in Europe (E-OBS). An ensemble size of twenty members is used to disentangle the contribution of two processes responsible for precipitation differences between WRF-Hydro simulations with and without land water routing, namely the changes in surface evaporation and the atmosphere chaotic behavior. It is found that the consideration of lateral terrestrial water flow increases the amount of summer precipitation through enhanced surface evaporation up to 10%, which reduces the bias to E-OBS.

How to cite: Arnault, J., Fersch, B., Rummler, T., Zhang, Z., Wei, J., Quenum, M., Graf, M., Laux, P., and Kunstmann, H.: Contribution of lateral terrestrial water flow to precipitation – A WRF-Hydro ensemble analysis and continental evaporation tagging for Europe, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-10223, https://doi.org/10.5194/egusphere-egu2020-10223, 2020.

EGU2020-465 | Displays | HS2.2.2

Multi-scale assimilation of SMAP data: comparison between land surface and land surface-subsurface model

Haojin Zhao, Roland Baatz, Carsten Montzka, Harry Vereecken, and Harrie-Jan Hendricks Franssen

Soil moisture plays an important role in the coupled water and energy cycles of the terrestrial system. However, the characterization of soil moisture at the large spatial scale is far from trivial. To cope with this challenge, the combination of data from different sources (in situ measurements by cosmic ray neutron sensors, remotely sensed soil moisture and simulated soil moisture by models) is pursued. This is done by multiscale data assimilation, to take the different resolutions of the data into account. A large number of studies on the assimilation of remotely sensed soil moisture in land surface models has been published, which show in general only a limited improvement in the characterization of root zone soil moisture, and no improvement in the characterization of evapotranspiration. In this study it was investigated whether an improved modelling of soil moisture content, using a simulation model where the interactions between the land surface, surface water and groundwater are better represented, can contribute to extracting more information from SMAP data. In this study over North-Rhine-Westphalia, the assimilation of remotely sensed soil moisture from SMAP in the coupled land surface-subsurface model TSMP was tested. Results were compared with the assimilation in the stand-alone land surface model CLM. It was also tested whether soil hydraulic parameter estimation in combination with state updating could give additional skill compared to assimilation in CLM stand-alone and without parameter updating. Results showed that modelled soil moisture by TSMP did not show a systematic bias compared to SMAP, whereas CLM was systematically wetter than TSMP. Therefore, no prior bias correction was needed in the data assimilation. The results illustrate how the difference in simulation model and parameter estimation result in significantly different estimated soil moisture contents and evapotranspiration.  

How to cite: Zhao, H., Baatz, R., Montzka, C., Vereecken, H., and Hendricks Franssen, H.-J.: Multi-scale assimilation of SMAP data: comparison between land surface and land surface-subsurface model , EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-465, https://doi.org/10.5194/egusphere-egu2020-465, 2020.

It is recognized that groundwater (GW) may play an important role in the subsurface–land-surface–atmosphere system and that pumping of GW may affect soil moisture which in turn influences local weather and climate through land-atmosphere interactions. In this study effects of GW pumping on ground surface temperature (GST) in the North China Plain (NCP) were investigated with a coupled ParFlow.CLM model of subsurface and land-surface processes and their interactions. The model was validated using the water and energy fluxes reported in previous studies and from the JRA-55 reanalysis. Numerical experiments were designed to examine the impacts of GW pumping and irrigation on GST. Results show significant effects of GW pumping on GST in the NCP. Generally, the subsurface acts as a buffer to temporal variations in heat fluxes at the land-surface, but long-term pumping can gradually weaken this buffer, resulting in increases in the spatio-temporal variability of GST, as exemplified by hotter summers and colder winters. Considering that changes of water table depth (WTD) can significantly affect land surface heat fluxes when WTD ranges between 1–10 m, the 0.5 m/year increase of WTD simulated by the model due to pumping can continue to raise GST for about 20 years from the pre-pumping WTD in the NCP. The increase of GST is expected to be faster initially and gradually slow down. The findings from this study may implicate similar GST increases may occur in other regions with GW depletion.

How to cite: Zhang, Y.-K., Yang, C., and Yang, X.: Effects of groundwater pumping on ground surface temperature: A regional modeling study in the North China Plain , EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-3198, https://doi.org/10.5194/egusphere-egu2020-3198, 2020.

The Yellow River Basin (795,000 km2) in Northern China has been greatly affected by intensive human activity and climate change over the past decades. In this study, a coupled atmospheric and hydrological modelling system is applied to investigating the long-term hydrological cycle and short-term forecasting of hydrological events in the Yellow River Basin. This modelling system (AHMS) combines a hydrological model (HMS) with the Weather Research and Forecast model (WRF) and the Noah land surface scheme (NoahMP-LSM), which has been recently improved to account for topographic influences in the infiltration scheme and to allow for interactions between the unsaturated and saturated zones by applying the Darcy-flux boundary condition. Here, simulations are performed using the offline AHMS mode over the Yellow River Basin by considering a time span of 25 years (1979-2003) and a spatial resolution of 20 km. The NCEP reanalysis dataset and observed precipitation data for the referred period are used as meteorological forcing data. The most important parameters affecting the hydrological process are identified by means of a parametric sensitivity analysis. Specifically, these main parameters are the Manning's roughness coefficient of channel, the soil infiltration capacity and the hydraulic conductivity of riverbed. To calibrate the values of these parameters for the Yellow River Basin, model predictions for daily streamflow are compared with the corresponding observational data at four hydrological gauging stations including Tangnaihe (TNH), Lanzhou (LZ), Toudaoguai (TDG) and Huanyuankou (HYK) on the mainstream of the Yellow River. Quantitative agreement is found between these observations and the simulation results for all stations. The progress achieved in the present work paves the way for a sediment flux model over the Yellow River Basin and demonstrates the good performance of AHMS for long-term hydrological simulations. 

How to cite: Jiang, C., J. R. Parteli, E., and Shao, Y.: Application of a Coupled Atmospheric and Hydrological Modelling System (AHMS) to the Yellow River Basin, China, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-5197, https://doi.org/10.5194/egusphere-egu2020-5197, 2020.

EGU2020-5696 | Displays | HS2.2.2

Long term hydrologic simulations for the meso-scale catchments Rur and Bode in Germany by TSMP

Zhenlei Yang, Wolfgang Kurtz, Sebastian Gebler, Lennart Schüler, Stefan Kollet, Harry Vereecken, and Harrie-Jan Hendricks-Franssen

Integrated terrestrial systems modeling is important for the comprehensive investigation of the coupled terrestrial water, energy and biogeochemical cycles. In this work, we applied the Terrestrial Systems Modeling Platform (TSMP) to the two meso-scale catchments in Germany (Rur and Bode) to conduct a long time hydrologic simulation with a focus on variables such as soil moisture, evapotranspiration (ET) and groundwater recharge. Simulations for the Rur and Bode catchments were performed at three different spatial horizontal model resolutions (1000, 500, and 200m) with CLM and CLM-PF in TSMP. Each of the three resolution models was run for 24 years (1995-2018) with transient atmospheric forcings derived from COSMO-REA6 data. The long term simulation results show that the summer of 2018 resulted in the lowest soil moisture content over the time series that is around 0.20, lower than the dry summers of 1995 and 2003. ET was more reduced in July-August 2018 due to the decrease of soil moisture content during this period. Nevertheless, actual evapotranspiration was even in the summer of 2018 often not limited by soil moisture content. For these catchments ET is most of the time energy limited. In addition, the vegetation evaporation (resulting from interception) accounts for the smallest percentage of the ET (ca. 20%), whereas the vegetation transpiration and soil evaporation account for almost the same percentage of the total ET (each 40% approximately). Both the CLM and CLM-PF simulation results indicate that grid coarsening (lower model resolution) leads to larger ET and soil moisture content, which is related to the decreasing slope gradient with grid coarsening. The analysis of groundwater recharge is underway.

How to cite: Yang, Z., Kurtz, W., Gebler, S., Schüler, L., Kollet, S., Vereecken, H., and Hendricks-Franssen, H.-J.: Long term hydrologic simulations for the meso-scale catchments Rur and Bode in Germany by TSMP, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-5696, https://doi.org/10.5194/egusphere-egu2020-5696, 2020.

EGU2020-6374 | Displays | HS2.2.2

Impacts of soil hydrologial modeling on long-term terrestrial carbon cycle inferred from CCDAS (Carbon Cycle Data Assimilation System)

Mousong Wu, Marko Scholze, Fei Jiang, Hengmao Wang, Wenxin Zhang, Zhengyao Lu, Wei He, Songhan Wang, Thomas Kaminski, Michael Vossbeck, Jun Wang, and Weimin Ju

The terrestrial carbon cycle is an important part of the global carbon budget due to its large gross exchange fluxes with the atmosphere and their sensitivity to climate change. Terrestrial biosphere models show large uncertainties in estimating carbon fluxes, which impacts global carbon budget assessments. The land surface carbon cycle is tightly controlled by soil moisture through plant physiological processes. In this context, accurate soil moisture data will improve the modeling of carbon fluxes in a model-data fusion framework. We employ the Carbon Cycle Data Assimilation System (CCDAS) to assimilate 36 years (1980-2015) of surface soil moisture data as provided by the ESA CCI in combination with atmospheric CO2 concentration observations at global scale. We will present the methods used for assimilating long-term remotely sensed soil moisture into the terrestrial biosphere model, and demonstrate the importance of soil moisture in modeling ecosystem carbon cycle processes. We will also investigate the impacts of soil moisture on the terrestrial carbon cycle during climate extremes at various scales.

How to cite: Wu, M., Scholze, M., Jiang, F., Wang, H., Zhang, W., Lu, Z., He, W., Wang, S., Kaminski, T., Vossbeck, M., Wang, J., and Ju, W.: Impacts of soil hydrologial modeling on long-term terrestrial carbon cycle inferred from CCDAS (Carbon Cycle Data Assimilation System), EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-6374, https://doi.org/10.5194/egusphere-egu2020-6374, 2020.

EGU2020-9214 | Displays | HS2.2.2

Multivariate data assimilation in a seamless sea ice prediction system based on AWI-CM

Longjiang Mu, Lars Nerger, Qi Tang, Svetlana N. Losa, Dmitry Sidorenko, Qiang Wang, Tido Semmler, Lorenzo Zampieri, Martin Losch, and Helge F. Goessling

We implement multivariate data assimilation in a seamless sea ice prediction system based on the fully-coupled AWI Climate Model (AWI-CM, v1.1). AWI-CM has an ocean/ice component with unstructured-mesh discretization and smoothly varying spatial resolution, which aims for seamless sea ice prediction across a wide range of space and time scales. The assimilation uses a Local Error Subspace Transform Kalman Filter coded in the Parallel Data Assimilation Framework. To test the robustness of the assimilation system, a perfect-model experiment is configured to assimilate synthetic observations. Real observations from sea ice concentration, thickness, drift, and sea surface temperature are further assimilated in the system. The analysis results are evaluated against independent in-situ observations and reanalysis data. Further experiments that assimilate different combinations of variables are conducted to understand their individual impacts on the analysis step. Particularly we find that assimilating sea ice drift improves the sea ice thickness estimate in the Antarctic, and assimilating sea surface temperature is able to avert a circulation bias of the free-running model in the Arctic Ocean at mid-depth. We also test the performance of an extended experiment where the atmosphere is constrained by nudging toward reanalysis data. The second version of the system assimilating more observations also with a new atmospheric model is currently under development.

How to cite: Mu, L., Nerger, L., Tang, Q., Losa, S. N., Sidorenko, D., Wang, Q., Semmler, T., Zampieri, L., Losch, M., and Goessling, H. F.: Multivariate data assimilation in a seamless sea ice prediction system based on AWI-CM, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-9214, https://doi.org/10.5194/egusphere-egu2020-9214, 2020.

EGU2020-10419 | Displays | HS2.2.2

Cosmic Ray Neutron Sensing: Integration with land surface modelling using data assimilation for improved field-scale soil moisture estimates

Amol Patil, Benjamin Fersch, Harrie-Jan Hendricks-Franssen, and Harald Kunstmann

Soil moisture is a key variable in atmospheric modelling to resolve the partitioning of net radiation into sensible and latent heat fluxes. Therefore, high resolution spatio-temporal soil moisture estimation is getting growing attention in this decade. The recent developments to observe soil moisture at field scale (170 to 250 m spatial resolution) using Cosmic Ray Neutron Sensing (CRNS) technique has created new opportunities to better resolve land surface atmospheric interactions; however, many challenges remain such as spatial resolution mismatch and estimation uncertainties. Our study couples the Noah-MP land surface model to the Data Assimilation Research Testbed (DART) for assimilating CRN intensities to update model soil moisture. For evaluation, the spatially distributed Noah-MP was set up to simulate the land surface variables at 1 km horizontal resolution for the Rott and Ammer catchments in southern Germany. The study site comprises the TERENO-preAlpine observatory with five CRNS stations and additional CRNS measurements for summer 2019 operated by our Cosmic Sense research group. We adjusted the soil parametrization in Noah-MP to allow the usage of EU soil data along with Mualem-van Genuchten soil hydraulic parameters. We use independent observations from extensive soil moisture sensor network (SoilNet) within the vicinity of CRNS sensors for validation. Our detailed synthetic and real data experiments are evaluated for the analysis of the spatio-temporal changes in updated root zone soil moisture and for implications on the energy balance component of Noah-MP. Furthermore, we present possibilities to estimate root zone soil parameters within the data assimilation framework to enhance standalone model performance.

How to cite: Patil, A., Fersch, B., Hendricks-Franssen, H.-J., and Kunstmann, H.: Cosmic Ray Neutron Sensing: Integration with land surface modelling using data assimilation for improved field-scale soil moisture estimates, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-10419, https://doi.org/10.5194/egusphere-egu2020-10419, 2020.

EGU2020-14140 | Displays | HS2.2.2

Developing an operational high-resolution hydrometeorological system in a Mediterranean region: predictability analysis of two case studies

Luca Furnari, Alfonso Senatore, Linus Magnusson, and Giuseppe Mendicino

Given the expected increase in the frequency and intensity of severe weather events due to global warming, improving weather forecasting capability in terms of both spatial resolution and lead times is a key factor for reducing extreme events impact. The climate of the Calabrian peninsula (southern Italy) is dominated by the interactions of the air masses with the surrounding Mediterranean Sea and strongly influenced by its complex steep orography, which often amplifies precipitation amounts worsening ground effects.

With the aim of investigating the capability of a state-of-the-art modelling chain to deliver accurate forecasts for civil protection purposes in the Calabria Region, an experimental high-resolution hydrometeorological modelling system has been developed recently at the Department of Environmental Engineering of the University of Calabria, providing forecasts up to the hydrological impact. The system is based on the Advanced Research WRF (ARW) mesoscale model in its version 3.9.1, with two one-way nested domains, the innermost having 2-km resolution. The boundary and initial conditions are provided operationally by the Global Forecasting System (GFS) in its high-resolution version and, for back-analysis purposes, by the European Centre for Medium-range Weather Forecasts’ Integrated Forecasting System (IFS). Finally, to simulate the hydrological impact of the atmospheric forcing, the WRF-Hydro 5.0 modelling system in a one-way mode with a horizontal resolution of 200 m is linked to the system and applied on all the main river networks of the region.

The accuracy and efficiency of the system have been tested with two events occurred in Autumn 2019. Though the synoptic conditions showed some significant differences, both the events affected mainly the central part of the region, causing about 230 mm and 200 mm of rainfall in 72 hours, on the 11-13 November 2019 and on the 24-26 November 2019, respectively. The analysis focused particularly on the predictability of the events, evaluating the forecast accuracy by considering lead times from one week early.

Preliminary results highlight the ability to forecasts the events well in advance, proved by the comparison of the simulated rainfall with the ground-based observations and the reproduction of the main hydrological signals in the basins affected by the events.

How to cite: Furnari, L., Senatore, A., Magnusson, L., and Mendicino, G.: Developing an operational high-resolution hydrometeorological system in a Mediterranean region: predictability analysis of two case studies, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-14140, https://doi.org/10.5194/egusphere-egu2020-14140, 2020.

EGU2020-16219 | Displays | HS2.2.2

How reservoir regulation modifies the regional terrestrial-atmospheric water cycle: Incorporation of a reservoir network module into a fully-coupled hydrological-atmospheric model

Jianhui Wei, Ningpeng Dong, Joël Arnault, Benjamin Fersch, Sven Wagner, Zhenyu Zhang, Patrick Laux, Chuanguo Yang, Qianya Yang, Zhongbo Yu, and Harald Kunstmann

The regional terrestrial-atmospheric water cycle is strongly altered by human activities. Among them, reservoir regulation is a way to spatially and temporally allocate the water resources in a basin for the purpose of, for example, flood control, agriculture development, ecosystem maintenance. However, it is still not well understood how the reservoir regulation modifies the regional terrestrial-atmospheric water cycle. To address this question, this study employs a fully-coupled regional Earth system modelling system WRF-HMS, which has a closed description of the water cycle in a ground-soil-vegetation-atmosphere continuum. A process-based reservoir regulation module is for the first time now implemented into WRF-HMS, which allows to represent reservoir regulation in one seamless atmosphere-hydrology modeling system. In addition, an online budget analysis of atmospheric moisture is implemented into WRF-HMS, so that the impact of reservoir regulation on the atmospheric branch of the water cycle is quantitatively analyzed. Our study focuses on the basin of the largest fresh water lake in China, the Poyang Lake basin. Four simulations with a horizontal resolution of 10 km are conducted for the investigation period of 1979 to 1986: the standalone HMS with/without the reservoir regulation module and the fully-coupled WRF-HMS with/without the reservoir regulation module. For the standalone simulations, the basin-averaged, multi-year mean results show that incorporating reservoir regulation leads to an increased evapotranspiration, a wetter soil, and a higher groundwater level. In addition, the interactions among river water, unsaturated zone, and groundwater are enhanced as well. Overall, the reservoir-enabled HMS model improves the streamflow simulation over the Poyang Lake basin on daily and monthly scales than the reservoir-disabled HMS model. For the fully coupled simulations, our preliminary results show that incorporating reservoir regulation also modifies the regional atmospheric branch of the water cycle, for example, moistening planetary boundary layer due to the enhanced evapotranspiration. Details about the results of the fully-coupled simulations will be presented in the conference.

How to cite: Wei, J., Dong, N., Arnault, J., Fersch, B., Wagner, S., Zhang, Z., Laux, P., Yang, C., Yang, Q., Yu, Z., and Kunstmann, H.: How reservoir regulation modifies the regional terrestrial-atmospheric water cycle: Incorporation of a reservoir network module into a fully-coupled hydrological-atmospheric model, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-16219, https://doi.org/10.5194/egusphere-egu2020-16219, 2020.

EGU2020-17772 | Displays | HS2.2.2

Assessing the interactions of atmosphere and land surface over South Africa with convective-permitting coupled atmospheric-hydrological modeling

Zhenyu Zhang, Joel Arnault, Patrick Laux, Jussi Baade, and Harald Kunstmann

Land degradation, as a major issue in South Africa, undermines water resources and land potential productivity, and threatens the ecosystem biodiversity and human activities. In the scope of accurately assessing the land degradation processes in multi-use landscapes, the atmosphere-land surface relations and the dynamics of land surface state variabilities need to be addressed in a detail. This requires Earth System modeling approaches jointly considering high-resolution atmospheric modeling, land surface and hydrological modeling frameworks. This study investigates the atmosphere-land interactions and land surface water-energy budget for South Africa using the Earth System Model WRF-Hydro. WRF-Hydro is the fully coupled atmosphere-land surface-hydrology modeling system, which enhances the Weather Research and Forecasting model with the overland and subsurface water routing processes. In the WRF-Hydro modeling setup, the atmospheric part is configured in a convection-permitting spatial resolution at 4 km, with horizontal grids of 650 × 500 points, covering area of Southern Africa. In the land surface, the gridded hydrological processes are routed on a 400 m fine hydrological subgrid, within a soil depth of 2 m. In this study, we perform the coupled simulation for the year of 2010 and show the validation of modeling results with multiple reference datasets. The water-energy budget in the land surface from coupled WRF-Hydro simulation is assessed on 22 primary hydrological drainage regions. Model results show that coupled atmospheric-hydrological modeling is able to represent the regional water and energy budget, and to resolve atmosphere-land surface interactions. This allows the further usage of the coupled atmospheric-hydrological modeling in the context of land degradation studies, e.g. under different land-use scenarios.

How to cite: Zhang, Z., Arnault, J., Laux, P., Baade, J., and Kunstmann, H.: Assessing the interactions of atmosphere and land surface over South Africa with convective-permitting coupled atmospheric-hydrological modeling , EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-17772, https://doi.org/10.5194/egusphere-egu2020-17772, 2020.

Accurate basic soil properties information is fundamental for obtaining reliable soil moisture using land surface models. In view of the passive microwave remote sensing, basic soil properties have an impact on soil dielectric constant, together with soil moisture and temperature. The common link enables to use coupled land surface model with microwave emission model for retrieving basic soil properties in space, especially in remote areas such as the third pole region. The Maqu site in the eastern Tibetan Plateau, including ELBARA-III radiometry observations, was taken as the case. This paper employed an improved observation operator— a discrete scattering-emission model of L-band radiometry with an air-to-soil transition model embedded in, which considers both geometric and dielectric roughness impacts from heterogeneous topsoil structure on surface emission. Community Land Model 4.5 together with Local Ensemble Transform Kalman Filter algorithm were used by mean of the Open Source Multivariate Land Data Assimilation Framework. The retrieved basic soil properties were compared to in situ measurements, as well as the update soil moisture and temperature and energy fluxes. The impacts from surface roughness consideration and polarization configuration on parameter retrieval were also evaluated. To gain an insight on the impact from time interval of observations on parameter retrieval, results using observations at SMAP descending and ascending time were discussed.

How to cite: Zhao, H., Zeng, Y., Su, B., and Han, X.: Retrieval of basic soil physical properties by assimilating radiometry observations in the community land surface model, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-19116, https://doi.org/10.5194/egusphere-egu2020-19116, 2020.

This research aims to observe the behaviour between heat flow at the limit of the unsaturated area and the earth's surface (evaporation) through different methods based on the surface energy balance. This behavior has been determined by the DRUtES. DRUtES is a free software able to determine the evaporation in the surface using climate and hydraulic parameters determined by the Richard equation. Richards’ equation describes the flow of water in an unsaturated porous medium due to the actions of gravity and capillarity neglecting the flow of the non-wetting phase, usually air (Farthing & Ogden, 2017). 

 

The results obtained have been compared with the Penman-Monteith potential evapotranspiration model, this one as a referenced value. The results obtained help to understand the loss of water in the unsaturated area. This first approach using DRUtES and evaporation methods will allow a deeper investigation in the future regarding the impact of climate change on climate variables and their effects on soil moisture (unsaturated area) and natural aquifer recharge.

Key words: Evaporation, surface energy balance, Richard's Equation, zone unsaturated, Penman-Monteith.

How to cite: Cárdenas-Castillero, G. and Arbelaez, J.: Application of the Surface Energy Balance in Richard's equation-based model using climatic data to calculate soil evaporation, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-20055, https://doi.org/10.5194/egusphere-egu2020-20055, 2020.

EGU2020-21037 | Displays | HS2.2.2

Forecasting of an extreme flood in mountainous area of North China based on WRF-Hydro with distributing parameters

Wei Wang, JIa Liu, Chuanzhe Li, Qingtai Qiu, and Yuchen Liu

The flood events in the mountainous area of northern China has the characteristics of high intensity and strong sudden occurrence, and atmospheric-hydrological coupling system can improve the forecast accuracy and prolong the lead time. This paper discusses the simulations of the enhanced WRF-Hydro model on a historical flood that occurrs in a mesoscale catchment of Taihang mountain on July 21, 2012. Firstly, the precipitation accuracy of WRF, WRF data assimilation, co-kriging merging method of radar QPE data are as three different input sources for WRF-Hydro. The results show that the rainfall of merging QPE can achieve better simulations in time and space. In addition, the rainfall of WRF assimilation data is obviously better than that of WRF, but still underestimates the rainfall values. The extreme event rainstorm mainly proceeds in 5 hours, and for the assimilation data, the spatio-temporal simulations of the rainfall data in the first 2 hours are slightly poor. Hence we compare the combination of the first few hours to use the merging QPE and following by assimilation precipitation as the model input. In addition, according to the parameters of the WRF-Hydro model, a gridding parameter calibration method based on topographic index is constructed.

How to cite: Wang, W., Liu, J., Li, C., Qiu, Q., and Liu, Y.: Forecasting of an extreme flood in mountainous area of North China based on WRF-Hydro with distributing parameters, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-21037, https://doi.org/10.5194/egusphere-egu2020-21037, 2020.

HS2.2.4 – Isotope and tracer methods: flow paths characterization, catchment response and transformation processes

EGU2020-5695 | Displays | HS2.2.4

Exploring the limits of conventional hydrograph separation

Paolo Benettin

The separation of runoff into different components, typically some “event” (or “new”) water as opposed to some “baseflow” (or “old”) water, is a task that has been attracting hydrologists for decades. The ability to separate runoff sources has implications for our understanding of hydrological processes and to predict changes due to e.g. deforestation or urbanization. Although the methodology has notably evolved during the years, the most conventional and widespread application involves a two-component separation achieved through stable isotopes or electrical conductivity measurements. Use of this approach is based on a strong assumption that is difficult to test in the field: the signatures of the two end-members either do not change during the event or their variations can be taken into account. By using extensive numerical tests, this contribution explores the limits of this assumption. Results highlight the importance of considering the time-varying contribution of soil water, which is not event-water nor baseflow, and show that the method can easily lead to incorrect estimates when the above assumption is not met.

How to cite: Benettin, P.: Exploring the limits of conventional hydrograph separation, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-5695, https://doi.org/10.5194/egusphere-egu2020-5695, 2020.

Hydrologic tracer timeseries data (e.g. of stable water isotopes in rainfall and streamflow) have often been analyzed by extracting summary metrics (like the mean transit time) that provide some information about the storage and turnover of water in a watershed, but are laden with ad hoc, implicit, and questionable assumptions. Consequently, inferences about water age and runoff generation processes may be artifacts of the methods, rather than true implications of the tracer data. Potentially more reliable metrics have been suggested recently (e.g. the ‘young water fraction’) but these do not make full use of the information content of the data. The StorAge Selection (SAS) approach relaxes the common (highly questionable) assumption of steady-state flow, and thus allows the full time-variability of the transit time distribution to be captured. However until now its application has required ad hoc functional forms and relationships to be chosen for the underlying SAS function and its time-variability. This introduces artifacts that can skew estimates of the volume and sensitivity of water turnover rates within the catchment, inhibit inference of complex or multi-modal distributions, and is a subjective complication that presents a barrier to use of the approach.

Is it possible to make extract information about catchment water storage, turnover, and transit times without imposing ad-hoc assumptions, and instead allow the data to guide us? Can we obtain a clearer view of how these systems retain and release water of different ages at different rates, and vary how they do so over time? Can doing so allow us to better test hypotheses, tell richer stories about transport in dynamic hydrologic systems? 

Three recent advances toward doing so have recently been developed. The first is to unify the analysis of flux quantity and age (or water celerity and velocity) in the form of an ‘age-ranked storage-discharge relationship’. This relationship captures how the discharge of water of different ages changes when there is a change in the overall discharge. It thus provides a clearer view of the catchment mechanics driving streamflow generation and thus discharge age dynamics.

The second is Multiresolution Estimation of StorAge Selection (MESAS), a non-parametric statistical learning method for determining this relationship. This method avoids the need to specify a functional form – instead the shape of the function is iteratively determined from a coarse to a fine resolution, up to a limit at which the capacity of the data to meaningfully constrain the form is maximized.

The third is the development of computational techniques to accelerate the statistical learning implementation using an explicit Jacobian formulation and GPU acceleration.

How to cite: Harman, C.: A statistical learning approach to extract information from hydrologic tracer timeseries, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-11765, https://doi.org/10.5194/egusphere-egu2020-11765, 2020.

Although their contribution was neglected in the past, inland waters play a significant role in the carbon cycle and affect CO2 global balance. Streams and rivers are now considered not only as pipelines but as active reactors able to collect and transform carbon from terrestrial ecosystems trough drainage, erosion, deposition and respiration. Quantifying the transfer of carbon from the terrestrial to the riverine ecosystems is thus of crucial importance to fully appreciate carbon cycle at the watershed, regional and global scales. Such transfer is largely controlled by the processes occurring in the critical zone where the carbon and water cycles are tightly coupled. Previous studies investigated how hydrological drivers can affect Dissolved Organic Carbon (DOC) concentration in streams highlighting an hysteretic and unsteady behavior for the DOC-discharge relationship. In this study, we focus on the drainage flux from hillslopes to stream and river networks during rainfall events combining a transport model for water and a model of carbon degradation in soil. Using high-frequency records of chloride and DOC in Plynlimon catchments (UK), we employ the recently developed StorAge Selection (SAS) theory to evaluate water travel time and its partition as evapotranspiration, discharge and storage. We combine this approach with the reactivity continuum  theory to model  carbon degradation along the flow paths using a gamma-distribution as probability density function of the quality. The developed model can thus predict not only the flux of DOC released from hillslopes but also its quality (i.e. lability). We also show how the variability of the DOC-discharge relationship can partially be explained by hydrological fluctuations.

How to cite: Grandi, G. and Bertuzzo, E.: Watershed dissolved organic carbon transport: a modeling approach combining water travel times and reactivity continuum, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-9033, https://doi.org/10.5194/egusphere-egu2020-9033, 2020.

EGU2020-10468 | Displays | HS2.2.4

Urban tracers for the characterization of particle transport processes in an agricultural catchment

Clarissa Glaser, Christiane Zarfl, Hermann Rügner, Amelia Lewis, and Marc Schwientek

Well-established relations between concentrations of total suspended solids (TSS) and the hydrophobic polycyclic aromatic hydrocarbons (PAHs) in bulk water samples make PAH ideal tracers to understand water and solid transport in catchments during high discharge events. In the study presented here, we trace particle-bound PAH concentrations in the Ammer River, Germany (annual mean discharge of 0.87 m³ s-1), during a rain event to deepen knowledge on particle origin and hydrological processes in the catchment. High-resolution temporal monitoring of discharge, TSS, particle characteristics, and PAHs was conducted over the course of an event at two sampling sites at the Ammer River. The sampling sites are located in the upper catchment and ~ 8km downstream of the upper sampling site at the outlet of the gauged catchment (134 km²), while the downstream sampling sites integrates inflowing water from tributaries and a wastewater treatment plant. High PAH particle loading demonstrates that particles in the river originate mainly from urban areas, introduced into the stream via combined sewer systems located in the upper catchment. These particles dominate the suspended particle flux over the temporal course of the event. Despite the integral suspended particle flux being nearly constant in between both sampling sites, particle quality changes which is represented by a decreased integral PAH flux and an increasing proportion of particulate organic carbon in the suspended particles. Decrease of PAH particle loading in the downstream direction suggest dilution by ‘cleaner’ particles from either un- or less contaminated or possibly leached sediments entering into the river. This shows that particle exchange between suspended and river bed sediments is more pronounced in downstream direction, demonstrating that sediment mobilisation plays a role for the overall particle flux. These results suggest that the catchment response of the Ammer River regarding the particle flux during rainfall is mainly dominated by the combined sewer system though particle exchange processes are also relevant. Urban tracers are hence helpful for understanding solid transport in catchments.

How to cite: Glaser, C., Zarfl, C., Rügner, H., Lewis, A., and Schwientek, M.: Urban tracers for the characterization of particle transport processes in an agricultural catchment, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-10468, https://doi.org/10.5194/egusphere-egu2020-10468, 2020.

EGU2020-18122 | Displays | HS2.2.4

Young water fractions at diverse time scales are driven by varying runoff generation processes in a Mediterranean small research catchment

Francesc Gallart, Pilar Llorens, Carles Cayuela, Matthias Sprenger, Jérôme Latron, and Pauline Saurat

The time water resides within a catchment has important implications for the water availability and quality for both ecosystem and human use. Here, we look at the short-term water transport using the concept of young water fraction (Fyw), defined as the proportion of water that is younger than 2-3 months. The study was conducted for the 0.56 Km2 sub-humid Can Vila catchment (Vallcebre Research Catchments). During a period of over 58 months, the isotope ratios (2H and 18O) of rainwater was sampled at 5-mm rainfall intervals and stream water was sampled at variable time intervals (30 minutes to 1 week) depending on flow.

The early results of this research revealed intense dynamics of Fyw in relationship with discharge: Fyw had values between 0 for low flows and around 1 for the highest flows. Yet, the high variability of discharge and flashy response behaviour in this catchment along with the relatively large discharge sensitivity (Sd) of Fyw implied that even if the maximum sampled discharges were exceeded by only 0.01% of time, about 25% of the Fyw associated to the highest flows were estimated to be missed by the stream water sampling. This behaviour may be associated with a response dominated by saturation runoff generation mechanisms during wet episodes, which are known to drive the main hydrological response of this catchment.

Nevertheless, these results are obtained when all the samples are lumped for the whole 58 month period, but when different 12-month windows are investigated, the behaviour of Fyw becomes more intricate. Indeed, the wetter year was associated with the largest Fyw and Sd values, but drier years had irregularly varying values poorly correlated to precipitation or runoff statistics. Thus, other runoff generation mechanisms previously identified, including Hortonian-type overland flow in small degraded areas, that lead to runoff of new (and hence young) waters for low to moderate flows, will play a special role.

Current research is comparing Fyw analyses for groups of events of the same class, supported by hydrograph separation analyses and hydrometric indicators, for better understanding the dynamic and complex response of Fyw in this catchment. Our work further advances the understanding of limitations and opportunities of the Fyw approach.

How to cite: Gallart, F., Llorens, P., Cayuela, C., Sprenger, M., Latron, J., and Saurat, P.: Young water fractions at diverse time scales are driven by varying runoff generation processes in a Mediterranean small research catchment, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-18122, https://doi.org/10.5194/egusphere-egu2020-18122, 2020.

EGU2020-9413 | Displays | HS2.2.4

Reduced fraction of young water in Alpine catchments with increased seasonal snow cover

Natalie Ceperley, Giulia Zuecco, Harsh Beria, Luca Carturan, Anthony Michelon, Daniele Penna, Joshua Larsen, and Bettina Schaefli

Effective water resource management can benefit from estimations of when water entered the catchment and how long it takes to flow to the outlet. In this context, the so-called young water fraction (Fyw) based on seasonal input and output tracer cycles is becoming increasingly used as robust tool to compare the hydrological function of catchments. In seasonally cold environments, this Fyw estimation is complicated by the fact that a large part of the precipitation will be in the form of snow, will be stored before melting and becoming available as water, resulting in a distinct winter low flow and summer high flow season. Nevertheless, Fyw might enclose extremely interesting information in such environments since they incorporate the relationship between late summer and autumn flow and the previous winter’s snow input.  However, most currently available methods for Fyw estimation do not explicitly account for the seasonal shift of water input from snow. Therefore, we propose a novel framework to explicitly account for this “snowmelt” delay in Fyw and explore related uncertainties using experimental data from three high-elevation Alpine catchments, the Vallon de Nant in Switzerland, and the Noce Bianco at Pian Venezia and the Bridge Creek Catchments in Italy. Experimental data from these environments expose some limitations of existing methods in accounting for unavoidable sampling inconsistencies. Using our method that explicitly accounts for snowmelt, we found extremely low Fyw in these three Alpine catchments: 6%, 13%, and 31%. In this contribution, we will present our method in detail and highlight emerging challenges and implications of the Fyw estimation.

How to cite: Ceperley, N., Zuecco, G., Beria, H., Carturan, L., Michelon, A., Penna, D., Larsen, J., and Schaefli, B.: Reduced fraction of young water in Alpine catchments with increased seasonal snow cover , EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-9413, https://doi.org/10.5194/egusphere-egu2020-9413, 2020.

EGU2020-11128 | Displays | HS2.2.4

A method for predicting hydrogen and oxygen isotope distributions across a region’s river network using reach-scale environmental attributes

Bruce Dudley, Jing Yang, Ude Shankar, and Scott Graham

EGU2020-10524 | Displays | HS2.2.4

The use of high-temporal resolution, in-situ sampling of stable isotopes of water to capture fine-scale hydrological responses

Amirhossein Sahraei, Philipp Kraft, David Windhorst, and Lutz Breuer

Hydrological responses to precipitation events in headwater catchments often vary in space and time. Understanding of such patterns leads to constrain runoff generation mechanisms and flow pathways. The use of stable isotopes of water combined with classical hydrometrics have increased in recent years to elucidate the response behavior of runoff components and their drivers in runoff generation. However, most of the previous studies dealing with investigation of catchment responses were limited to daily to monthly data, at which potential fine-scale variations could not be captured. Recently, few studies applied high-temporal resolution sampling of stable isotopes of water to investigate isotopic response variation within precipitation events. Sampling sources were mostly limited to streamflow and precipitation. An important, yet poorly known mechanism is the response of shallow groundwater to precipitation.

In this study, we used an automated in-situ mobile laboratory to continuously sample stable istopes of multiple sources, including stream water, groundwater and precipitation every 20 mintutes. The study was realized in the Schwingbach Environmetal Observatory (SEO) in Hesse, Germany. Hydrograph seperation technique was applied to quantify the share of event and pre-event water contribution to the stream and to estimate response times of maximum event water fractions in the stream water and the groundwater for 20 events in the dry year 2018. We investigated the control of precipitation and antecedent wetness hydrometrics on response characteristics using Spearman rank correlation analysis.

High-temporal resolution sampling of multiple sources captured the fine-scale variation of isotope concentrations in stream water and groundwater sources during the precipitation events indicating that the Schwingbach is a highly responsive, pre-event water dominated creek. More than 79% of the runoff consisted of pre-event water. Short response times combined with soil moisture variations of different depths revealed the linkage between shallow groundwater in near-stream zones and the stream itself. As a response of the dry conditions in 2018, an extended crack network developed that acted like adrainage system causing rapid delivering of water to the stream network. Event water contribution increased with increasing precipitation amount. Pre-event water contribution was moderately affected by precipitation amount, while antecedent wetness did not influence the runoff generation. The response time of stream water and groundwater was controlled by mean precipitation intensity. A two-phase system was identified, at which the response times of stream water and groundwater started to decrease after reaching a threshold of mean precipitation intensity (0.5 mm h1).

How to cite: Sahraei, A., Kraft, P., Windhorst, D., and Breuer, L.: The use of high-temporal resolution, in-situ sampling of stable isotopes of water to capture fine-scale hydrological responses, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-10524, https://doi.org/10.5194/egusphere-egu2020-10524, 2020.

EGU2020-18750 | Displays | HS2.2.4

Borehole equilibration: testing a new method to monitor the isotopic composition of tree xylem water in situ

John Marshall, Matthias Cuntz, Matthias Beyer, Maren Dubbert, and Kathrin Kuehnhammer

Forest water use has been difficult to quantify. One promising approach is to measure the isotopic composition of plant water, e.g.
the transpired water vapor or xylem water, which often differs from that of other water vapor sources. Traditionally such
measurements have relied on the extraction of wood samples, which provide limited time resolution at great expense, and risk
possible artefacts. Utilizing a borehole drilled through a trees’ stem, we propose a new method based on the notion that water
vapor in a slow-moving airstream approaches equilibration with the much greater mass of liquid water in the xylem. We present
two empirical data sets showing that the method can work in practice. We then present theoretical models estimating the
equilibration times and exploring the limits at which the approach will fail. Given long enough boreholes and slow enough flows,
the method provides a simple, cheap, and accurate means of continuously estimating the isotopic composition of the source water
for transpiration.

How to cite: Marshall, J., Cuntz, M., Beyer, M., Dubbert, M., and Kuehnhammer, K.: Borehole equilibration: testing a new method to monitor the isotopic composition of tree xylem water in situ, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-18750, https://doi.org/10.5194/egusphere-egu2020-18750, 2020.

EGU2020-9840 | Displays | HS2.2.4

Groundwater recharge estimates with soil isotope profiles – is there a bias on coarse-grained hillslopes?

Nina Krüger, Christoph Külls, Adriana Bruggeman, Marinos Eliades, Christos Christophi, Michali Rigas, and Theodosia Eracleous

Due to continuous changes in the meteorological conditions of Mediterranean regions, it is becoming increasingly important to improve knowledge of hydrological and hydrogeological recharge processes and their dependency on climate conditions to adapt the use of limited water resources. Within the IsoMed project (isotope hydrology in Mediterranean areas), soil profiles were sampled in November 2018 and February 2019, from various hydrogeological settings in Cyprus to estimate groundwater recharge using stable isotope equilibration methods combined with soil water balance modeling. A total of 11 soil profiles were taken from the Troodos massif (Galata and Platania) and the Mesaoria plain in Deftera, Nicosia. A vertical profile of stable isotopes has been determined with a 2 cm resolution and measured with Tunable Diode Laser spectrometry. Percolation through the soil profile has been estimated based on the convolution of a seasonal input function using advection-dispersion transport models. In Galata, groundwater percolation estimates range from 20-30 mm/y on clayey soil with natural vegetation to 100-120 mm/y at an irrigated terraced orchard. The results in Platania vary from 20-60 mm/y at steep hillslopes under natural vegetation and amount to 220-340 mm/y in the root zone at the irrigated site with olive trees in Deftera. The comparison of groundwater percolation rates based on stable isotope profiles with those derived from soil water balance modeling indicates a significant bias. While percolation rates correspond well to results obtained from a daily soil water balance model for irrigated fine-grained soils in the plain, recharge rates obtained from stable isotope profile methods on coarse-grained hillslopes tend to be much lower than expected. The observed bias suggests that stable isotope methods, regardless of water extraction or equilibration technique, mainly record the isotope signal of matrix flow. Thus, macro-pore and preferential flow components in coarse-grained soils may not be accounted for. Data collected from the same profiles in late autumn and spring suggest that macro-pore and preferential flow constitute a major component of percolation in coarse-grained shallow hillslope soils of Troodos indeed, without leaving measurable isotope traces in the soil water profile. Additional approaches need to be applied in conjunction with methods based on the evaluation of soil water isotope profiles to overcome this limitation.

How to cite: Krüger, N., Külls, C., Bruggeman, A., Eliades, M., Christophi, C., Rigas, M., and Eracleous, T.: Groundwater recharge estimates with soil isotope profiles – is there a bias on coarse-grained hillslopes? , EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-9840, https://doi.org/10.5194/egusphere-egu2020-9840, 2020.

EGU2020-932 | Displays | HS2.2.4

A Wet Layered Sloping Sponge? The Role of Volcanic Ash Soils in Water Transport and Tracer Mixing at a Tropical Hillslope

Giovanny Mosquera, David Windhorst, Lutz Breuer, and Patricio Crespo

Hillslope soils developed on volcanic ash (Andosols) provide key hydrological services such as water storage and streamflow regulation in montane environments. Yet, little is known about how they influence subsurface water flow paths and flow transport and mixing dynamics. To fill this knowledge gap, we analyzed a unique 3-year dataset of hourly precipitation, soil moisture, and groundwater level and weekly precipitation and soil water stable isotope data collected along a steep hillslope transect underlain by Andosols. In combination with a detailed characterization of soil properties, we investigated how these soils influence water transport and tracer mixing in the subsurface. Our results indicate that the high organic matter (33-42%) and clay (29-31%) content of the soils’ organic horizon and an abrupt change in hydraulic conductivity between the highly conductive rooted soil layer and a low conductive underlying layer results in a perched water layer that remains near saturated year-round. Despite the formation of the latter, our isotope-based water age estimations depict that water resides within the organic horizon of the soils for short periods (2-4 weeks). The dynamics of soil moisture suggest a fast transfer of hydraulic potentials (few hours) along the entire soil profile in response to rainfall events. This hydraulic response is explained by the exponential shape of the soils’ water retention curves that facilitate a rapid vertical mobilization of water through the porous soil matrix. These findings indicate that the hydrological behavior of volcanic ash soils resemble that of a “layered sponge” in which vertical flow paths are dominant despite the formation of a perched water layer. 

How to cite: Mosquera, G., Windhorst, D., Breuer, L., and Crespo, P.: A Wet Layered Sloping Sponge? The Role of Volcanic Ash Soils in Water Transport and Tracer Mixing at a Tropical Hillslope, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-932, https://doi.org/10.5194/egusphere-egu2020-932, 2020.

The volume and scale of mountain-block groundwater circulation plays an important role in watershed hydrologic function; carbon, geochemical and nutrient budgets; and response to climate change.  However, mountain block groundwater remains one of the least understood components of the hydrologic cycle.  In this project, we investigate the role of bedrock groundwater circulation on groundwater age and isotopic tracer concentration on soil-mantled mountainous hillslopes.  We perform numerical modeling of variably saturated soil, saprolite and bedrock groundwater flow, groundwater age, and transport of a suite of environmental tracers including stable isotopes of water, tritium, dissolved CFC’s and SF6.  We use these models to investigate patterns of bed-rock groundwater circulation, and the distribution as well as integrated discharge of groundwater age and tracer concentration.  We identify first order processes controlling the spatial distribution and volume of groundwater circulation on hillslopes, the partitioning between slope parallel through-flow versus bedrock recharge, and the resulting hillslope age and tracer dynamics. Monte-Carlo simulations are used to evaluate the relative role of topography, soil characteristics, underlying lithology and antecedent moisture conditions in governing the age and tracer distribution. The basic relationships derived provide new insight into the role of bedrock groundwater recharge and discharge on hillslope age and tracer distribution.  Model results are compared with observed patterns of water level and stable isotopes measured in soil and bedrock groundwater on hillslopes in west-central Montana, United States. These results can be used to help hydrogeologists develop better conceptual models and estimates of bedrock groundwater circulation in upland catchments and its role in watershed hydrologic and biogeochemical function.

How to cite: Gardner, W. P.: Spatial and Temporal Patterns of Soil and Bedrock Groundwater Age and Age Tracer Concentration on Soil-Mantled Mountainous Hillslopes, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-12668, https://doi.org/10.5194/egusphere-egu2020-12668, 2020.

EGU2020-11384 | Displays | HS2.2.4

Using environmental tracers to characterize groundwater flow in an alpine watershed underlain by sedimentary rock

Andrew H. Manning, Lyndsay B. Ball, Richard B. Wanty, Philip L. Verplanck, and Kenneth H. Williams

A growing number of studies indicate that bedrock groundwater is an important component of streamflow in mountain watersheds, yet mountain fractured-rock aquifers remain poorly characterized largely due to a lack of wells. Environmental tracer data from springs and tunnels can provide useful information, but are limited by the fact that spring occurrence is sporadic, and tunnels often disturb the natural groundwater system by acting as deep drains. We present dissolved noble gas, age tracer (3H, 3He/4He, and SF6), chemistry, and temperature data from two relatively deep (46 and 81 m) boreholes and multiple shallow hand-drilled stream-side piezometers in Redwell Basin, Colorado, USA. The snowmelt-dominated watershed is underlain by sub-horizontally bedded, hydrothermally altered (sulfide-rich) sandstones and shales, and is being studied to better understand hydrogeochemical processes controlling sulfide weathering and metal exports from mineralized mountain headwater catchments. The boreholes were completed with multi-level monitoring wells allowing discrete-depth sampling, and the stream-side piezometers provided integrated samples of groundwater discharge at various points along the stream course. The chemistry of deeper groundwater at depths >10-20 m is markedly different from that of shallow groundwater: pH is 7-8 versus 4-6; specific conductance is 400-600 versus 100-300 μS/cm; and concentrations of multiple metals (e.g., Fe, Zn) are lower by a factor >5. Apparent 3H/3He and SF6 ages for the shallow groundwater are mainly 5-15 yr, whereas the deeper groundwater is dominantly premodern (>60 yr old) with high terrigenic He concentrations of 4-8 times solubility. Preliminary results from a 2D coupled heat and fluid flow model calibrated with the tracer-based ages and temperature data from the two deep boreholes suggest that active groundwater circulation (Darcy velocities >1 cm/yr) below a depth of 10-20 m is unlikely. This circulation depth is considerably shallower than previously reported depths of generally 100-200 m for mountain watersheds (these being underlain dominantly by crystalline rock), and is probably due to low vertical hydraulic conductivity (K) of the altered sedimentary rocks. Noble gas, age, and chemistry data from the piezometers suggest little to no deep, stream-parallel flow from upper to lower parts of the basin, further supporting relatively shallow active groundwater circulation. The age and chemistry of the piezometer samples also display spatial variations likely attributable to K anisotropy in the bedrock aquifer. The tracer, chemistry, and temperature data thus provide information critical for the development of reliable conceptual and numerical hydrogeochemical models of the watershed.

How to cite: Manning, A. H., Ball, L. B., Wanty, R. B., Verplanck, P. L., and Williams, K. H.: Using environmental tracers to characterize groundwater flow in an alpine watershed underlain by sedimentary rock, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-11384, https://doi.org/10.5194/egusphere-egu2020-11384, 2020.

Diverse tools do exist to study the pathway from the source of a contamination to groundwater and related springs. The backward approach, i.e. sampling spring water to determine the origin of contamination, is more complex and requires multiple information. Microbial source tracking using host-specific markers is one of the tools, which however has shown to be insufficient as a stand-alone method, particularly in karst groundwater catchments.    

A karst spring in the Swiss Jura Mountains was studied with respect to the occurrence and correlation of a set of fecal indicators, including classical parameters as well as a number of bacteroidale markers. Sporadic monitoring proved the impact on spring water quality, mainly during high water stages. Additional event-focused sampling over varying recharge intensities evidenced a more detailed and divergent pattern of individual indicators. In particular, the results arose the question how to interpret peaks of human fecal markers in the rural-dominated catchment.

A multiple-tool approach, complementing fecal indicator monitoring with artificial tracer experiments and natural tracers measurements, assessed the input, storage and transfer of potential contaminants in order to specify the origin of both ruminant and human fecal contaminations. Natural tracers allowed for distinguishing between water components from the saturated zone, from the soil/epikarst storage, or from freshly infiltrated rainwater. Furthermore, the breakthrough of injected dye tracers, and their remobilization during subsequent recharge events, respectively, were correlated to the occurrence of fecal markers. System’s residence time distribution over discharge, deduced from numerous former dye tracing tests, also allowed for attributing maximum travel distances to their arrival.

The findings of the approach hypothesize the origin of human fecal contamination at the spring being in relationship with septic tanks undergoing concentrated overflow already at moderate rainfall intensities. Those intensities are, however, not sufficient to transport diffuse ruminant contamination through the vadose zone. Linkage with vulnerability assessment and land-use information can finally better locate the potential source points. Such toolbox provides not only useful basics for groundwater protection and catchment management, but also insight into general processes governing fate and transport of fecal contaminants in a karst groundwater environment.

How to cite: Sinreich, M.: Multiple-tool approach of combining microbial markers with artificial and natural tracers to specify the origin of fecal contamination in a karst groundwater catchment , EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-19440, https://doi.org/10.5194/egusphere-egu2020-19440, 2020.

EGU2020-6766 | Displays | HS2.2.4

Finding the Information of the Unknown DNAPL Residual Source using various tracer data, Wonju, Korea

Seong-Sun Lee, Il-Ryoung Cho, Yeojin Ju, and Kang-Kun Lee

In this study, analytical solution method which can evaluate and quantify the impacts of partial mass reduction by remedial action performed in study site is applied to estimate the unknown DNAPL source mass and dissolved concentration using long-term monitoring data collected from 2009 to 2019. Also, noble gas tracer method was applied to identify the partitioning processes which can be happened in TCE contaminated site. By using the source zone monitoring data during about 10 years and analytical solution, initial dissolved concentration and residual mass of TCE in spilled period at the main source zone were roughly estimated 150 mg/L and 1000 kg, respectively. These values decreased to 0.45 mg/L and 33.07 kg direct after an intensive remedial action performed in 2013 and then it expected to be continuously decreased to 0.29 mg/L and 25.41 kg from the end of remedial actions to 2020. From results of quantitative evaluation using analytical solution, it can be evaluated that the intensive remedial action had effectively performed with removal efficiency of 70% for the residual source mass during the remediation period. From the results of noble gas analysis, the distance from TCE source zone was divided into three groups from Zone 1 to 3. Zone 1 includes samples that are the closest from the TCE main source, and are highly partitioned to TCE compared to other zones. Zone 3 samples show least accordance with either of the fractionation lines, showing that sampling points are influenced highly by other mechanism rather than partitioning to TCE. Also, it is identified that seasonal variation of groundwater level can be affected to the distribution of noble gas at around TCE source zone. Samples from only “High TCE” zone are plotted along with ideal batch equilibrium and Rayleigh fractionation line again and divided into two groups according to their sampling date. From August 2018 to October, 2018, samples shift from right to left in the figure, getting closer to Rayleigh fractionation line. In August, noble gas was relatively in equilibrium between groundwater and TCE. However, as water table rises, noble gas became touch with residual TCE locating above the previous water-level, which is a receiving fluid in water-TCE system. Results of this study was support that it was able to estimate the unknown quantitative information for TCE contamination and noble gas as the indicator of DNAPL contamination could be applied in allocating the DNAPL source which is relatively hard to estimate.

How to cite: Lee, S.-S., Cho, I.-R., Ju, Y., and Lee, K.-K.: Finding the Information of the Unknown DNAPL Residual Source using various tracer data, Wonju, Korea, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-6766, https://doi.org/10.5194/egusphere-egu2020-6766, 2020.

EGU2020-7323 | Displays | HS2.2.4

What can short temporal changes of stable isotope ratios and geochemical parameters of tap water at a single sampling site tell us?

Klara Nagode, Tjaša Kanduč, Tea Zuliani, Branka Bračič Železnik, Brigita Jamnik, and Polona Vreča

Investigations of tap water and its source groundwater reflect combined features of regional hydrological processes and human activities including the changes in water supply system (WSS). In this context, multi-parameter characterization can present a reliable tool to propagate the geochemical “fingerprints” of water source from natural or artificial mixing. If the geochemical composition of different water source end members is significantly different, we can estimate the proportions of source water and their changes from particular source to tap.

To test this hypothesis, we performed a 24 hours sampling experiment of tap water in April 2019 at selected location in Ljubljana (i.e. at Jožef Stefan Institute), where groundwater from two different water fields and aquifers (i.e. from Kleče at Ljubljansko polje and Brest from Ljubljansko barje) is mixed. In-situ measurements of temperature, electrical conductivity and pH were performed and 25 water samples were collected hourly for determination of isotopic composition of oxygen (δ18O), hydrogen (δ2H) and dissolved inorganic carbon (δ13CDIC), 87Sr/86Sr isotope ratio and major (Ca, K, Mg and Na) and trace elements (Ag, Al, As, B, Ba, Cd, Co, Cr, Cu, Fe, Li, Mn, Mo, Ni, Pb, Rb, Sb, Se, Sr, Tl, U, V and Zn).

The diurnal variations of parameters are not very large; however, temporal differences of some parameters (e.g. Ba, Mg) indicate that proportion of groundwater from Kleče and Brest water fields changed during the experiment. Based on observed temporal differences during the 24 hours experiment we could identify three different patterns: a.) higher values in the beginning and at the end and lower in between (i.e. δ18O, δ13CDIC, Ca, Na, B, Ba, Cr, Li, Sr); b.) lower values in the beginning and at the end and higher in between (i.e. K, Mg, As, Mn, V) and c.) higher values at the beginning of experiment (i.e. Cd, Co, Cu, Fe, Mo, Ni, Pb, Sb, Zn). The first and the second pattern (a and b) indicate the mixing of different groundwater from different water fields with different geochemical characteristics. The third pattern (c) however indicates the influence of release of elements due to corrosion of water supply system. Based on results of 24 hours experiment and additional information on functioning of water supply system changes in proportion of water from Kleče and Brest water fields will be estimated.

How to cite: Nagode, K., Kanduč, T., Zuliani, T., Bračič Železnik, B., Jamnik, B., and Vreča, P.: What can short temporal changes of stable isotope ratios and geochemical parameters of tap water at a single sampling site tell us?, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-7323, https://doi.org/10.5194/egusphere-egu2020-7323, 2020.

EGU2020-7180 | Displays | HS2.2.4

Application of stable isotope ratios in drinking water supply system of Ljubljana, Slovenia

Polona Vreča, Klara Nagode, Tjaša Kanduč, Branka Bračič Železnik, and Brigita Jamnik

The key to understand the deterioration of the quality of urban water resources is to know the impact of urbanization on the entire waterway, which can change dramatically during the extreme climatic events. Various geochemical parameters, including stable isotope ratios of light elements (H, O, C), represent an important tool to investigate water sources, transport routes, and the mixing of individual components of the water cycle. They are indispensable in urban hydrology, both for characterizing drinking water resources and for evaluating changes within a complex water system.

In Slovenia, the majority of the population is supplied with drinking water from groundwater. In Ljubljana, the capital city of Slovenia, groundwater represents the main drinking water resource.  Therefore, the knowledge and understanding of the groundwater vulnerability is important for the protection and management of water resources. In Ljubljana, the water is supplied through the central water system (WSS), more than 1.000 km long, according to the legislation and the latest standards from five different wellfields (Kleče, Hrastje, Brest, Jarški prod and Šentvid). Despite the established water protection areas, the water supply areas are exposed to the pressures of urbanization, industry, transport, agriculture and old environmental burdens, which are often unknown.

In the past, various short-term isotopic studies have been conducted and the Ljubljansko polje and Ljubljansko barje aquifers were characterized. In addition, the sources, paths and interactions of water were determined and the obtained data were used to improve the conceptual model.

However, isotopic studies of water circulation in the drinking water supply system (WSS), which would cover the simultaneous characterization of water sources and changes within the WSS, have not been performed so far. In order to assess the usefulness of isotopes more systematically, we performed the first more detail sampling of water from WSS of Ljubljana in autumn 2018. Sampling was carried out at 103 locations that were selected according to the type of facility in the WSS (i.e. 41 wells, 7 joint exits from water pumping station, 22 water reservoirs, 2  water treatment locations, 13 fountains, and 19 taps) and according to 9 different WSS areas. Additional samples were collected on River Sava, important infiltration source of groundwater, and at outflow from Ljubljana central wastewater treatment plant. This contribution focuses on presentation of changes of different parameters (i.e. temperature, electrical conductivity, pH, total alkalinity, δ18O, δ2H and δ13C) in WSS of Ljubljana.

How to cite: Vreča, P., Nagode, K., Kanduč, T., Bračič Železnik, B., and Jamnik, B.: Application of stable isotope ratios in drinking water supply system of Ljubljana, Slovenia, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-7180, https://doi.org/10.5194/egusphere-egu2020-7180, 2020.

EGU2020-11099 | Displays | HS2.2.4

Tracking water pathways and origins in cranberry production: Isotope hydrology application

Jenifer Gadomski, Silvio Gumiere, Thiago Gumiere, Genevieve Bordeleau, and Alain Rousseau

New scientific advances based on integrating water management approaches have been developed in order to reduce the environmental footprint. Cranberry production is one of the most influential cultures in Canada, where water is substantial for irrigation, harvesting, and frost control. The cranberry farms are considered closed-circuits. Water is mainly recycled in large pools, increasing the risk of accumulation of chemical substances affecting the quality of irrigation water. The use of isotopic geochemistry provides an additional layer of information for studying hydrological phenomena in agriculture.

The main objective of this project is to identify the sources and sinks of the water in a typical cranberry farm with the help of isotopic hydrology technics and groundwater surveys.

Water samples for stable isotope of the water molecule analysis (16O, 17O, 18O, 1H, 2H)  were collected during the growing season from May to September (from 2017 to 2020). Preliminary results have shown that isotope hydrology technics can be used to trace the water pathway is a cranberry farm by using the mixing model. 

These results can help to implement integrated water management procedures helping to increase fruit yields and to reduce environmental impact. Isotope mixing model also makes it possible to assess water losses by infiltration into the aquifers and by evaporation.

How to cite: Gadomski, J., Gumiere, S., Gumiere, T., Bordeleau, G., and Rousseau, A.: Tracking water pathways and origins in cranberry production: Isotope hydrology application , EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-11099, https://doi.org/10.5194/egusphere-egu2020-11099, 2020.

The direct liquid-vapour equilibration (DLVE) method is a new method to measure the stable isotopes of oxygen and hydrogen in soil pore water. Advantages of DLVE are (a) minimum sample handling, (b) direct isotope measurement from the samples without the need of extracting the water, (c) comparatively low costs, (d) and high reliability. However, the impact of different water content and equilibration times on the isotope measurement of different soil types is not well understood yet. Therefore, this study focuses on advancing our knowledge of the effect of different soil types and soil water contents on the isotope measurement of the DLVE method. Three different types of soil (sand, silt and clay) representing sediment samples with different pore sizes were saturated using tap water with a known isotopic value in a water bath. Different degrees of saturation (100%, 80%, 60% and 40%) were established, placed in Ziploc bags and equilibrated for different time spans ranging from 1 hour up to 8 days at constant surrounding temperature (about 20oC). The isotope measurements were obtained using cavity ring down laser spectroscopy (CDRS) for each test samples. The time taken for the H2O(liquid)-H2O(vapour) equilibration for different soil textures and different water contents in Ziploc bags were determined. Results showed that sandy soil samples took shorter time to reach isotopic equilibrium with the headspace in the Ziploc bags compared to clayey soil which took comparatively longer for the same soil saturation level. Regardless of the soil type, 100% saturated soil samples took shorter time to reach liquid-water equilibration compared to low saturated soil samples. These findings could lead to protocols of soil sample measurements using DLVE regarding the influence of different soil textures and soil moisture contents.

How to cite: Vadibeler, D., Stockinger, M., Wassenaar, L. I., and Stumpp, C.: Influence of soil texture and degree of saturation on the equilibration time of water isotope in closed systems using direct H2O(liquid) - H2O(vapour) equilibration method, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-17547, https://doi.org/10.5194/egusphere-egu2020-17547, 2020.

Treatments on plantation forests, such as thinning, have a significant effect on the quality and quantity of water resources in the watersheds in Japan. However, few studies have performed intensive observations regarding the effects of thinning on the groundwater flow process with combined use of tracers, specially over a long period of time.

In this study, stable isotope analysis and hydrological observations were applied to investigate the temporal variation of spring water and groundwater mean residence time in a small watershed at Mount Karasawa, Tochigi Prefecture, Japan. We have monitored the research area since 2010, with periodical sampling once a month for 9 years, with a lack of data in some years after the thinning.  We analyzed the date for three different time periods, those are: Before Thinning, from July 2010 to September 2011, Soon After Thinning, from November 2011 to October 2013 and Long After Thinning, from September 2017 to August 2019.

The mean residence time of spring water and groundwater were evaluated by using the stable isotopes of hydrogen and oxygen as tracers, then estimating their d-excess variations using two Lumped-Parameter Models, Exponential-Piston Flow Model and Dispersion Model. The SF6 concentrations were used as an Apparent Age analysis for determination of the model’s parameters. Both models show a tendency of the mean residence time getting older Soon After Thinning and then getting younger again Long After Thinning.

According to a selection of the best model for this area, the Exponential-Piston Flow Model shows that the spring water mean residence time was 25 months Before Thinning, 30 months Soon After Thinning and 26 months Long After Thinning; the groundwater at 15m deep mean residence time was 39 months Before Thinning, 46 months Soon After Thinning and 38 months Long After Thinning and the groundwater at 30m deep mean residence time was 38 months Before Thinning, 47 months Soon After Thinning and 45 months Long After Thinning. These results suggest that Soon After Thinning there is a reduction of forest interception and tree evapotranspiration, leading to an increase in infiltration and groundwater storage. Then, Long After Thinning, the forest interception and tree evapotranspiration rise back again with the recovery of the understory vegetation, which leads to a decrease in infiltration and groundwater storage.

How to cite: Silveira Baptista, I., Tsujimura, M., and Onda, Y.: Long-term Temporal Variation of Mean Residence Time in Spring and Groundwater After Thinning at a Forested Headwater Catchment , EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-6522, https://doi.org/10.5194/egusphere-egu2020-6522, 2020.

EGU2020-13048 | Displays | HS2.2.4

Stable isotopic content of atmospheric precipitation and natural waters in the vicinity of Barentsburg (Svalbard) in 2016-2018.

Aleksandra Skakun, Alexey Ekaykin, Anna Kozachek, Kirill Tchikhachev, Diana Vladimirova, and Sergey Verkulich

In 2016–2018, during Russian Arctic Expedition on Svalbard (RAE-S) we have collected the samples of atmospheric precipitation, terrestrial waters, snow and ice on West Spitsbergen island in the vicinity of Grønfjorden. The measurements of stable water isotope content (δ18O and δD) in the atmospheric precipitation collected in Barentsburg has allowed to draw the Local Meteoric Water Line and to analyze the relationship between the isotopic content and air temperature. Aside from this, the d-excess values in precipitation (dexc = δD – 8δ18O) was interpreted as a marker of the moisture source. This fact was confirmed by HYSPLIT modelling of atmospheric moisture. It has been demonstrated that the isotopic content of the surface waters (lakes and rivers on mountain glacier valleys) clearly points to the dominating type of feeding (atmospheric, ground) of these hydrological objects. We have discovered the small annual variability of the isotopic composition of Lake Kongress water during 2 years and defined the sources of water in its tributes: 13 of them have atmospheric source and 9 with ground source. In general, isotopic content of water in the vicinity of Grønfjorden (mean values are: δ18O = –10,3 ‰, δD = –72,5 ‰) is higher than in other regions of Svalbard.

How to cite: Skakun, A., Ekaykin, A., Kozachek, A., Tchikhachev, K., Vladimirova, D., and Verkulich, S.: Stable isotopic content of atmospheric precipitation and natural waters in the vicinity of Barentsburg (Svalbard) in 2016-2018., EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-13048, https://doi.org/10.5194/egusphere-egu2020-13048, 2020.

EGU2020-807 | Displays | HS2.2.4

Characterising water sources in glacierized catchments in the northern Tien Shan using stable isotopes

Zarina Saidaliyeva, Maria Shahgedanova, Andrew Wade, Vadim Yapiyev, Vassiliy Kapitsa, Nikolay Kasatkin, and Igor Severskiy

The Kishi and Ulken Almaty rivers drain glacierized catchments in the northern Tien Shan, Kazakhstan. Both rivers supply water for the Almaty agglomeration with population around 2.5 million. Changes in discharge of these [and many other regional] rivers are affected by changes in all components of the cryosphere (seasonal snow, glacier ice, ground ice) as well as precipitation and ground water. Uncertainties of projections of water availability in the context of the observed climatic warming are an important economic and politic issue in this region. Knowledge of the extent, to which discharge of these rivers depends on different sources of nourishment, is important for the formulation of regional adaptation strategies and policies.

A comprehensive data set on concentrations of daily values of stable isotopes of oxygen and hydrogen, temperature, precipitation, and discharge was collected in both catchments in 2017 and 2018 in order to characterize contribution of different sources of water to total discharge. There is a clear correlation between isotopic concentrations in stream water with temperature, precipitation and discharge enabling separation between contributions of ground water (δ2H=–78.25 ‰; δ18O=–11.80 ‰), snow melt (δ2H=–84.56 ‰; δ18O=–13.20 ‰), and glacial melt (δ2H=–78.97 ‰; δ18O=–12.41 ‰). Analysis of isotopic signatures of sources of water shows separation between seasonal snow, glacier ice, rock glaciers and permafrost.

Following these preliminary results, the sampling programme has been extended in 2019 to the Ulken Almaty and Kishi Almaty (Kazakhstan), Ala-Archa and Chon Kyzyl-Cuu (Kyrgyzstan), Chirchik (Uzbekistan), Varzob-Kofarnihon (Tajikistan) catchments in 2019-2020 enabling the development of the most comprehensive data set on water isotopes in Central Asia.

How to cite: Saidaliyeva, Z., Shahgedanova, M., Wade, A., Yapiyev, V., Kapitsa, V., Kasatkin, N., and Severskiy, I.: Characterising water sources in glacierized catchments in the northern Tien Shan using stable isotopes, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-807, https://doi.org/10.5194/egusphere-egu2020-807, 2020.

EGU2020-1721 | Displays | HS2.2.4

Estimating mixing processes of sources contributing to baseflow in Alpine headwater catchments

Marius G. Floriancic, Clément Roques, and Joaquin Jimenez-Martinez

Baseflow is fed by groundwater to a large fraction. Estimating water quantity and quality from groundwater stores is essential for water management. However, there are few datasets available that contain detailed water chemistry analysis on high spatial resolution across multiple headwater catchments in (high) Alpine environments. This information is essential to analyze mixing processes on catchment scale from distinct landscape features.

We use two data sets: i) water chemistry analysis snapshot sampling campaigns in 7 headwater streams during low‑flow periods across Switzerland, and ii) a detailed chemical screening (every 25 m) in one selected catchment during baseflow, including electric conductivity and temperature. Major ions, stable isotopes, TOC, DOC, trace elements were analyzed for some of the samples (> 80). These data reveal the chemical fingerprint of the contributing groundwater sources. The chemical composition of these contributing sources to baseflow is largely influenced by weathering products depended on lithology and geomorphology. Using maximum likelihood calculations, we define the ion composition and the isotopic signature of the potential major endmembers (up to three), based on the mixed samples along the main stem.

The proposed methodology allows to i) reduce uncertainty of the endmembers, and ii) quantify the relative contribution of different lithology and geomorphological features to streamflow and shows iii) which spatial scale of input information is needed to analyze mixing processes from various groundwater sources. Our results show how the contribution of different lithologies, along with topography and geomorphological features, varies spatially throughout Alpine headwater catchments.

How to cite: Floriancic, M. G., Roques, C., and Jimenez-Martinez, J.: Estimating mixing processes of sources contributing to baseflow in Alpine headwater catchments, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-1721, https://doi.org/10.5194/egusphere-egu2020-1721, 2020.

The identification of origin, flow paths and transit times of water in catchments is an important component for process-based model development for runoff prediction. Hydrological studies offer, combined with isotope data, the possibility to quantify interactions between different compartments in catchments. In the context of this work it is examined to what extent event sampling of precipitation, streamflow, soil water and groundwater and the evaluation of their isotopic ratios δ2H and δ18O enable complex hydrological process investigations in the small forested mountain catchment of the river Große Ohe in the Bavarian Forest National Park. Within this study process analyses are carried out on small scales, e.g. runoff formation on hill slopes and on catchment scale as integrative process analysis. The water samples were collected during a small flood event and analysed for the isotope ratios δ2H and δ18O using a Picarro. A hydrograph separation was carried out through a comprehensive evaluation of the concentration profiles during the event. In combination with further hydrological and soil hydrological observations possible areas of origin and retention times of the water were determined. A strongly delayed reaction of the groundwater was observed which suggests that groundwater is not contributing to stream flow during a flood event, but a possible mobilization of pre-event water in the riparian zone can be observed as a response to precipitation events. The knowledge gained hereby is the basis for further process analysis and model development.

How to cite: Rommel, L. and Wöhling, T.: Hydrological analysis of runoff formation in a small forested mountain catchment using δ2H and δ18O ratios, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-10309, https://doi.org/10.5194/egusphere-egu2020-10309, 2020.

EGU2020-7713 | Displays | HS2.2.4

Reconciliation of catchment travel times derived from tritium and deuterium

Julian Klaus, Nicolas Rodriguez, Laurent Pfister, and Erwin Zehe

Catchment travel time distributions (TTDs) are an integrative measure of time-varying flow paths and hydrological processes, commonly derived from tracer data (e.g. 2-H, 3-H). Recently, it has been argued that the use of stable isotopes of O and H compared to tritium neglects the long tails of TTDs and thus truncates our vision on streamflow age. However, the reasons for the truncation of the TTD remain obscured by methodological and data limitations, including different mathematical models and sampling strategies. In this study, we apply composite SAS functions to a forested headwater catchment in Luxembourg, where the complexity of streamflow generation leads to flow paths with highly different TTDs. We calibrate the model with high-frequency (sub-daily) deuterium measurements, as well as nearly 30 tritium stream samples collected over a two-year period. We simulated TTDs based on each tracer individually and jointly. We found that, when using the two tracers in a coherent methodological framework, both tracers result in similar TTD and storage for the studied catchment. We found small differences in the TTDs that might be explained by calculation uncertainties, as well as by the limited sampling frequency for tritium. Using both stable and radioactive isotopes of H as tracers reduced uncertainties in the water age and storage calculations. While tritium and stable isotopes delivered redundant information about younger water, the use of both tracers leveraged the more specific information content of tritium on longer ages in the system. The two tracers had overall different information contents. We found that 30 tritium samples contained more bits of information than approximately 1000 deuterium samples, underlying the importance of complementing stable isotopes studies with tritium data.

How to cite: Klaus, J., Rodriguez, N., Pfister, L., and Zehe, E.: Reconciliation of catchment travel times derived from tritium and deuterium, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-7713, https://doi.org/10.5194/egusphere-egu2020-7713, 2020.

EGU2020-7080 | Displays | HS2.2.4

Quantitative estimation of genetic components in the seasonal runoff of a small river by the graphoanalytic and isotopic method

Julia Chizhova, Maria Kireeva, Natalia Tebenkova, and Alexey Kositsky

The processes of spring flood formation associated with intensive snow melting are becoming less and less predictable, and forecasts of such important characteristics as maximum discharge and water level do not fit into the allowable ranges of error. In some areas, a sharp decrease in river runoff was observed, followed by catastrophic floods, associated with the anomalous hydrometeorological conditions and an unfavorable combination of flow-forming factors. All this testifies to the change in runoff formation processes in regions with a significant share of snow-fed rivers. A new method of storing processing and visualizing of the information is developed to bridge the gap between point data on river runoff and globally distributed data on characteristics affecting the genetic components of runoff. The use of new model for separating runoff into genetic components was verified by isotope hydrograph separation.

Under unsteady climate conditions, the isotope signature of river water within a year and on a multi-year scale is an important indicator of the response of hydrological system to change (associated with different amounts of snow in the winter and different contributions of snow melting to the river and groundwater reservoir). Observations at the local site of the Protva River catchment on the European Plain showed that over 9 years (in 2009-2010 and in 2019), the groundwater component did not change its isotopic characteristics: δ18О = -12.3 ‰. The intra- and interannual fluctuations associated with different amounts of atmospheric precipitation entering the upper groundwater horizon practically did not shift oxygen isotope composition of water. In 2014, the weighted average annual value δ18О of the precipitation for Moscow was -12.1‰ (Chizhova et al., 2017). The δ18О value of precipitation in the summer months varies from -3 to -10 ‰. In Protva river runoff in mid-summer the contribution of precipitation is from 16 to 34% according to the isotope hydrograph separation. This work was supported by RSF project 19-77-10032.

How to cite: Chizhova, J., Kireeva, M., Tebenkova, N., and Kositsky, A.: Quantitative estimation of genetic components in the seasonal runoff of a small river by the graphoanalytic and isotopic method, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-7080, https://doi.org/10.5194/egusphere-egu2020-7080, 2020.

EGU2020-22346 | Displays | HS2.2.4

Disturbed forest affects the hydrological processes in a small mountain catchment

Roman Juras, Yuliya Vystavna, and Soňa Hnilicová

Hydrological response covered by disturbed forest catchments are in a focus of hydrologist last decades, mainly because the connection with widespread droughts. In this study, we compare two mountain catchments in Šumava Mts. (Czech Republic), both with small glacial lakes. Plešné lake catchment is characterised by disturbed forest by a bark beetle calamity. Contrary, Čertovo lake catchment features with undisturbed forest. Both catchments have comparable geological, climate setting and origin forest types. Stable isotopes of water were used for determining the hydrological pathways and water residence time. The results show that the state of the forest significantly affects the water balance of the catchments, but the mean residence time seems to be independent on this. On the other hand, even small changes in water residence time are important for the solutes and nutrients transport in the catchments. The lakes are fed by surface and subsurface water originating from liquid precipitation in and mostly snow in winter. The isotopic analysis helps to understand how much the snow cover affects the water balance during the hydrological year in two catchments with different forest stands.

How to cite: Juras, R., Vystavna, Y., and Hnilicová, S.: Disturbed forest affects the hydrological processes in a small mountain catchment, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-22346, https://doi.org/10.5194/egusphere-egu2020-22346, 2020.

EGU2020-11960 | Displays | HS2.2.4

Young water dominance in the humid tropics in Costa Rica

Alicia Correa, Christian Birkel, Jason Gutierrez, Joni Dehaspe, Ana María Duran-Quesada, Chris Soulsby, and Ricardo Sánchez-Murillo

The headwater catchments in the humid tropical forests are of major hydrological importance for regional and global climate systems and provide essential ecosystem services such as water supply for other ecosystems and industrial use in the lowlands. Anthropogenic pressure together with global environmental changes critically alter the hydrological functioning of these catchments. However, limited knowledge jeopardizes a proper water resources management of such water towers.

To contribute to filling this gap, we conducted a field monitoring of hydro-climatic and isotopic data (01.2013 – 07.2018) in a pristine tropical rainforest catchment (3.2 km2) in Costa Rica and used this data to test hypotheses about water age dynamics. The Spatially-Distributed Tracer-Aided Rainfall-Runoff model for the tropics (STARRtropics) was applied in high temporal (hourly) and spatial (10m) resolution. The best-obtained model simulations reflected a highly variable range and distribution of water ages. Nevertheless, superficial flow paths with young water contributions (40 months at most) dominate the streamflow generation entirely. The maximum water age was independently evaluated calculating the tritium-derived baseflow mean transit time. The highest simulated ages of transpiration flux varied between 12 days and 5.5 months depending on the soil depths where the water was uptake. Soil water age peaked at 5.4 months and groundwater at 40 months. The oldest stream water age, integrating all catchment processes, reached 24 months. Overall, the water age increased during dry conditions. The frequency of water ages reflected high occurrences of young water for transpiration flux and streamflow in their respective ranges. Maximum occurrences were reported for transpiration with 10 hours and streamflow with 2.8 months. The soil water age presented a bimodal distribution with peaks of 2.8 and 4.4 months and groundwater age occurrences peaked at 32 and 37 months. Spatially, high age dynamics of transpiration flux were associated with a higher leaf area index on the northern hillside in relation to the southern hillside. The oldest soil water was related to more developed soils and the groundwater age increased towards the bottom of the catchment. In the context of the tropics, our study is one of the first that quantitatively evaluated water age dynamics and distributions, and globally using such a high spatial and temporal resolution with a non-stationary perspective. These findings will support decision-makers to manage the water resources and ecosystem in the humid tropics and reduce the research gap regarding hydrological processes of tropical headwater towers under environmental changes.

How to cite: Correa, A., Birkel, C., Gutierrez, J., Dehaspe, J., Duran-Quesada, A. M., Soulsby, C., and Sánchez-Murillo, R.: Young water dominance in the humid tropics in Costa Rica, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-11960, https://doi.org/10.5194/egusphere-egu2020-11960, 2020.

EGU2020-414 | Displays | HS2.2.4

Using stable isotopes to understand water flow paths and ages in complex urban catchments

Christian Marx, Chris Soulsby, Reinhard Hinkelmann, and Dörthe Tetzlaff

The need to understand how urbanization impacts the hydrological cycle and creates a complex, hybrid system of artificial and natural flow paths is an increasing focus of research.  A key question is how routing processes are affected by preferential flow of urban runoff into storm drains and infiltration trenches, and how this affects catchment travel time distributions of water and groundwater recharge. Isotopic tracers are commonly used in hydrology in order to identify dominant runoff sources, track flows paths and estimate water ages. However, isotope studies in urban areas are surprisingly scarce.  Here, we address this research gap by using stable isotopes for a preliminary investigation of the effects of urbanization on the stream flow generation and groundwater  discharge in the Panke catchment (230 km²) in the northern part of Berlin. The Panke is highly urbanised, with the built areas occupying 30% of the catchment, and a waste water treatment plant (WWTP) for around 700,000 people. Daily isotope samples of precipitation and streamflow were collected through the transition period from summer (dry) to winter (wet) conditions. In addition, spatially synoptic surveys in summer and winter gathered samples from throughout the catchment surface water drainage network and numerous groundwater wells. The natural hydrology of the catchment is groundwater-dominated, with isotopes indicating that an aquifer of glacial sands and gravel still providing the main source of runoff in the catchment headwaters, upstream of Berlin. Increasingly downstream, urban impacts become more dominant, especially during high flows when urban storm drains are active. In addition, the isotopic imprint of discharge from a WWTP dominates baseflow composition in the lower catchment. This preliminary work will be extended throughout 2020 and ultimately seek to inform models to quantify how the travel time distributions of the catchment have changed due to urban drainage, and how both impermeable surfaces and urban green space affect the spatial distribution of groundwater recharge.

 

How to cite: Marx, C., Soulsby, C., Hinkelmann, R., and Tetzlaff, D.: Using stable isotopes to understand water flow paths and ages in complex urban catchments, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-414, https://doi.org/10.5194/egusphere-egu2020-414, 2020.

EGU2020-6430 | Displays | HS2.2.4

The Use of Stable Isotope-Based Water Age to Evaluate a Hydrodynamic Model

Edward Gross

Coastal lagoons are unique and complex ecosystems. Resulting from both terrestrial (fresh groundwater and surface water) and marine water influences, these ecosystems are often maintained by direct or indirect groundwater supplies and collectively known as groundwater dependent ecosystems (GDEs). Because they provide a wide range of ecosystem goods and services on which a large part of the human population depends, coastal GDEs are considered as complex socio-economic and ecological component worldwide. The increasing human development in coastal areas induces yet a strong pressure on water resources and the expected effects of climate change could exacerbate the pressures on these environments. To limit the risks of degradation and to ensure the sustainability of ecosystem services, the implementation of proper water resources management strategies is essential. This requires a strong knowledge of the environmental and socio-economic trajectories of hydrosystems, and particularly of the behavior and role of groundwater.

To this end, only the combined use of several tools allows a global understanding of the spatial and temporal dynamics of the system. The correlation between isotopic tracers (18O, 2H, 3H, 15N, 11B), anthropogenic contaminants (organic micro pollutants) and mapping approaches (land-use and vulnerability) allows a historical analyze of the hydrosystem. In addition, to better constraint the hydrosystem hydrological behavior, it is also possible to highlight the current status of water resources, the historical legacy of pollutants and the consequences of past developments and practices, which continue to jeopardize the current quality of the water resource. This methodology was applied to a Mediterranean hydrosystem, in connection with a coastal lagoon (Corsica Island, France). The identification of degradation processes and their chronology could then be traced back in time.

It appears that the current deterioration is mainly due to a legacy pollution resulting from the development of policies implemented 60 years earlier. In the case of coastal GDEs that are highly anthropized and subject to ever-increasing development, this methodology proposes new key elements for the establishment of relevant management strategies to ensure the future sustainability of water resources.

How to cite: Erostate, M., Huneau, F., Garel, E., and Pasqualini, V.: Multi-method approach combining isotopic tracers, anthropogenic contaminants and mapping to retrace socio-environmental trajectories of groundwater-dependent coastal hydrosystems, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-18387, https://doi.org/10.5194/egusphere-egu2020-18387, 2020.

Widespread permafrost thaw in Canada's western Arctic has led to formation of shoreline retrogressive thaw slumps (SRTS), a process influential in modifying water and biogeochemical balances of tundra lakes. To investigate hydrological effects of SRTS, water sampling campaigns were conducted in 2004, 2005 and 2008 for paired lakes (pristine vs catchments disturbed by SRTS) in the upland region adjacent to the Mackenzie Delta, Northwest Territories, Canada. An isotope balance model to estimate evaporation/inflow, precipitation/inflow, water yield and runoff ratio was developed incorporating seasonal evaporative drawdown effects and a vapour mixing model to simulate gradients in Beaufort Sea marine air versus continental moisture sources. Site- specific water balance results reveal systematically higher evaporation/inflow and precipitation/inflow for lakes with active SRTS compared to undisturbed lakes, and typically higher ratios for lakes with stabilized versus active SRTS. For lake catchments, water yield is found to be higher for active SRTS sites compared to undisturbed and stabilized SRTS sites, suggesting that slumping is an initial but not a sustained source of water delivery to lakes. Catchments with history of wildfire are found to have lower water yields, attributed to reduced permafrost influence. Conceptually, we define a thaw trajectory whereby undisturbed sites, active SRTS, stabilized SRTS, and ancient- SRTS define progressive stages of permafrost thaw. We postulate that release of additional runoff is mainly due to permafrost thaw in active SRTS which also promotes lake expansion, talik formation, and subsurface connectivity. Eventual stabilization of slumps and reduced runoff is expected once permafrost thaw sources are exhausted, at which time lakes may become more reliant on replenishment by direct precipitation. The effect of snow catch in slumps appears to be subordinate to thawing based on eventual decline in runoff once thaw slumps stabilize. Improved, site-specific hydrologic understanding will assist ongoing research into carbon cycling and biogeochemical feedbacks.

How to cite: Wan, C. and Zhou, Z.: Isotopic constraints on water balance of tundra lakes and watersheds affected by permafrost degradation, Mackenzie Delta region, Northwest Territories, Canada, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-18415, https://doi.org/10.5194/egusphere-egu2020-18415, 2020.

Abstract

Wetlands play an important role in the hydrologic cycle and are also regarded as major water reservoirs. Hydrochemistry application is an important tool which enables the evaluation of water type, water-rock interactions, discharge and recharge mechanism of wetlands. The aim of this study is to clarify the hydrogeochemical processes involving recharge and discharge mechanism of the wetland system and determine the hydrochemical characteristics of the wetland water, based on groundwater and surface water chemistry data. Within this scope; a detailed geological, hydrological, hydrogeological, hydrochemical and isotopic studies were performed in the Seyfe Lake catchment. Seyfe Lake and its surroundings, which is located in Mucur district, approximately 16 km northeast of Kirsehir, Turkey, is a first degree natural reserve and Ramsar Site. First field campaign was carried out in September 2019 and twenty three sampling points were selected in the study area. Sampling points were chosen from the wetland area and wells and springs that are located in the recharge area. Physicochemical parameters such as pH, specific electrical conductivity, temperature and discharge rates of the water samples were measured in-situ. Temperature, specific electrical conductivity and pH of the water samples ranges from 14.5°C to  21.2°C, from 370 µS/cm to 30500 µS/cm and from 7.15 to 8.65, respectively. Discharge rate of the springs are between 0.02 and 1 l/s. These waters have neutral to slightly alkaline character. Stable isotopes and hydrochemistry are used to identify possible recharge areas, origin of waters, groundwater-surface water relation and water-rock interactions. The δ2H and δ18O values of the water samples ranges between -27.61‰ to -80.88‰, and -11.97‰ to 0.86‰, respectively in the Seyfe wetland area. The results of this study will contribute to a better understanding of groundwater dynamics and hydrochemical processes in the wetland area.

Key words: Hydrochemistry, Stable isotopes, Wetland, Ramsar site, Seyfe Lake, Kirsehir

How to cite: Yurteri, C.: Hydrochemical evaluation of a groundwater system connected to a wetland: A case study in the Seyfe Lake wetland, Kirsehir, Turkey, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-27, https://doi.org/10.5194/egusphere-egu2020-27, 2020.

EGU2020-8105 | Displays | HS2.2.4

Triple isotope balance of groundwater controlled lake

Kazimierz Rozanski, Anna Pierchala, Marek Dulinski, Zbigniew Gorczyca, and Robert Czub

Stable isotopes of hydrogen and oxygen (2H and 18O) are often used for quantification of water budgets of lakes and other surface water bodies, in particular for the assessment of underground components of those budgets [1]. Recent advances in laser spectroscopy enabled simultaneous analyses of 2H, 18O and 17O content in water, with measurement uncertainties comparable (18O) or surpassing (2H) those routinely achieved by off-line sample preparation methods combined with conventional IRMS technique [2]. This open up the doors for improving reliability of isotope-aided budgets of surface water bodies by adding third isotope tracer (17O).

Here we present the results of a field study aimed at assessing water balance of a small groundwater-controlled lake (surface area ca. 40 ha, mean depth 5.2 m) located in southern Poland. The lake has no surface inflows and outflows and is heavily exploited for recreational purposes during the summer season. Thus, the renewal rate of water in the lake is of primary importance for proper management of this system.

The lake has been extensively monitored during one–year period (from October 2018 till September 2019). Four sampling campaigns were conducted on the lake to collect water samples for isotope analyses. In addition, regular observations of lake water temperature and meteorological parameters (air temperature, precipitation amount, relative humidity, wind speed) were conducted on the shore. Also, monthly precipitation samples were collected for isotope analyses.

The lake budget was constructed separately for each isotopic system (2H, 18O, 17O), with groundwater inflow and outflow fluxes treated as unknowns. The isotopic composition of net evaporation flux was calculated using Craig-Gordon model [3]. Isotope mass balance calculations revealed that groundwater fluxes derived from 2H-based budget deviate substantially from those obtained for 18O and 17O isotope. It turned out, that most likely reason of this discrepancy is the assumption generally made in constructing isotope balances of small lakes that atmospheric water vapor “seen” by the evaporating lake, is in isotopic equilibrium with local precipitation. Instead, when the local water vapor “seen” by the lake was assumed to be a mixture of local free atmospheric moisture (in equilibrium with local precipitation) and the vapor produced by the lake itself, consistent water budget for all three isotope systems could be obtained.

   

Acknowledgements: The presented work was supported by National Science Centre (research grant No. 2016/23/B/ST10/00909) and by the Ministry of Science and Higher Education (project no. 16.16.220.842 B02)

 

References:

[1]  Rozanski K. Froehlich K. Mook WG. Technical Documents in Hydrology, No. 39, Vol. III, UNESCO, Paris, 2001 117 pp.     

[2]   Pierchala A, Rozanski K, Dulinski M, Gorczyca Z, Marzec M, Czub R, Isotopes in Environmental and Health Studies, 2019 (55) 290-307.

[3]   Horita, J. Rozanski K. Cohen S. 2007. Isotopes in Environmental and Health Studies, 2007 (44), 23-49.

 

How to cite: Rozanski, K., Pierchala, A., Dulinski, M., Gorczyca, Z., and Czub, R.: Triple isotope balance of groundwater controlled lake , EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-8105, https://doi.org/10.5194/egusphere-egu2020-8105, 2020.

HS2.3.1 – Water quality at the catchment scale: measuring and modelling of nutrients, sediment and eutrophication impacts

EGU2020-20724 | Displays | HS2.3.1 | Highlight

Beyond the Mass Balance: Watershed phosphorus legacies and the evolution of the current water quality policy challenge

Nandita Basu, Kimberly Van Meter, Phillipe Van Cappellen, Yuhe Liu, Meghan McLeod, Roland Hall, and Guy Tenkuano

Increased use of phosphorus (P) fertilizers and detergents, as well as the growth of animal feeding operations, have more than doubled P inputs to human-impacted watersheds over pre-industrial levels. While P fertilizer use and manure application help to maximize crop yields, excess P is lost to runoff, leading to eutrophication of downstream waters—a phenomenon of great concern in the North American Great Lakes region. Excess P also accumulates across the landscape, leading to legacies that serve as long-term sources of P to surface waters, even after inputs to the watershed are reduced. We developed, for the first time, a process-based model, ELEMeNT-P, designed to capture legacy P accumulation and depletion trajectories along the land-aquatic continuum. To drive the model, we reconstructed a more than 100-year trajectory of P inputs to the Grand River Watershed (GRW), Canada’s largest river basin draining directly to Lake Erie. Our results show that since 1900 the GRW has served as a net P sink, with an estimated accumulation of more than 480 ktons P, of which 89% resides in soils and 6% in reservoirs and riparian areas. Future simulations suggest that while a 40% reduction in P discharge to Lake Erie is possible under aggressive management scenarios, legacy P will continue to elevate P loads to Lake Erie for centuries.

How to cite: Basu, N., Van Meter, K., Van Cappellen, P., Liu, Y., McLeod, M., Hall, R., and Tenkuano, G.: Beyond the Mass Balance: Watershed phosphorus legacies and the evolution of the current water quality policy challenge, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-20724, https://doi.org/10.5194/egusphere-egu2020-20724, 2020.

Long-term Soluble Reactive Phosphorus (SRP) monitoring in headwater streams in central Europe revealed a seasonal pattern of SRP concentrations during low flow periods, with highest concentrations in summer and lowest in winter. These seasonal concentration amplitudes often exceed the eutrophication threshold during the summer eutrophication-sensitive period. It is assumed that temperature dependent biogeochemical processes control the underlying P release mechanism, where redox processes may be responsible for this increase. Several studies have highlighted the crucial role of reactive zones such as riparian wetlands in controlling solute export regimes. Moreover especially in forest headwater streams, in-stream assimilatory uptake shows a distinct seasonal behaviour because of varying shading conditions. This can also lead to seasonal SRP amplitudes. Furthermore sorption and desorption processes are temperature dependent which may alter in-stream SRP release during the year.

Often SRP concentrations are higher in agricultural streams than in more pristine headwaters. It is not clear how land use (e.g. P status of soils) may impact the baseline SRP concentrations and which factors control the seasonal change in SRP stream concentration (riparian groundwater heads and redox processes, temperature, in-stream release and uptake processes). Therefore the objective of this study is to disentangle land use impacts from hydrological and biogeochemical controls of low flow SRP losses.  A comparative study on seasonal SRP concentration patterns will be presented comprising around 53 long term monitored headwater catchments in humid temperate climate of northern Europe and the United States. Based on hydrological and SRP headwater signals and catchment properties, P release processes are discussed. The results of the study will allow to target SRP mitigation strategies based on knowledge of the dominating control of SRP loss from headwater streams. 

How to cite: Rode, M. and Dupas, R.: Major controls of base flow soluble reactive phosphorus losses in humid temperate headwater streams , EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-4625, https://doi.org/10.5194/egusphere-egu2020-4625, 2020.

EGU2020-7081 | Displays | HS2.3.1

Assessing the role of colloidal phosphorus delivery processes in groundwater-fed agricultural catchments

Maelle Fresne, Phil Jordan, Karen Daly, Owen Fenton, and Per-Erik Mellander

Soil colloids with high sorbing capacities can enhance transport of phosphorus (P) from soils to groundwater and the delivery of P to surface water via groundwater pathways. However, only particulate and dissolved P fractions are generally monitored at the catchment scale.

To add important insights into the particulate to dissolved P concentration spectrum in the soil-water environment, the role of colloidal P delivery processes to surface water was studied in two agricultural catchments. The catchments were dominated by belowground pathways but had contrasting land use (arable and grassland). Particulate, coarse colloidal (0.20 – 0.45 μm) and finer colloidal (< 0.20 μm) P fractions were monitored along hillslopes in the free soil solution, shallow groundwater and stream water on a weekly basis for background characterisation and at higher frequency during rainfall events. An automated sampler was deployed in the stream and an automated, low-flow and low-disturbance sampler was developed to sample groundwater. Multi-parameter probes were also deployed to monitor stream water and shallow groundwater physico-chemical parameters. Stream discharge was measured at high frequency using a flow velocimeter in order to quantify P loads, apportion hydrological pathways and study concentration-discharge hysteresis.

Preliminary findings showed higher background P and unreactive P concentrations in the stream and groundwater in the grassland catchment. In the arable catchment (rainfall event in June 2019) P was mainly lost through deeper baseflow (92% of the total event flow) as reactive P in the finer colloidal fraction (0.070 mg P/ha) and only a small fraction lost as particulate unreactive P (0.008 mg P/ha). In the grassland catchment (rainfall event in October 2019), P was mainly lost through quickflow (37% of the total flow) even tough deeper baseflow was also important (33%). Losses were mainly reactive P in the finer colloidal fraction (13.6 mg P/ha) but also as unreactive P (4.5 mg P/ha). Concentration-discharge hysteresis suggested a smaller and easily mobilised P source in the arable catchment and a larger P source, followed by the mobilisation of a second but smaller source via a second hydrological surface pathway in the grassland catchment.

Further monitoring campaigns during more rainfall events in the grassland catchment are required to better understand colloidal P delivery and the spatial/temporal dynamics between rainfall events in relation to soil conditions and rainfall patterns. This will help to better target mitigations measures according to P species and fractions, hydrological flowpaths, and rainfall patterns – important in the context of a changing climate.

How to cite: Fresne, M., Jordan, P., Daly, K., Fenton, O., and Mellander, P.-E.: Assessing the role of colloidal phosphorus delivery processes in groundwater-fed agricultural catchments, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-7081, https://doi.org/10.5194/egusphere-egu2020-7081, 2020.

EGU2020-8229 | Displays | HS2.3.1

A systems approach to modelling phosphorus pollution risk in Scottish rivers using Bayesian Belief Networks

Miriam Glendell, Andy Vinten, Samia Richards, Zisis Gagkas, Allan Lilly, Nikki Baggaley, Malcolm Coull, Nick Schurch, Alessandro Gimona, Ina Pohle, Mads Troldborg, and Marc Stutter

Water pollution is an important reason for the failure of 17 % of Scottish waterbodies to reach Good Ecological Status under the Water Framework Directive (WFD). Among the multiple pressures affecting water quality, phosphorus (P) pollution is a major cause of surface water quality failures. Reducing the P pollution in agricultural catchments requires evidence-based decision-making about the effectiveness of land management mitigation measures and their spatial targeting, under current conditions and future scenarios.

Here we introduce a decision-support tool, PhosphoRisk, that uses a Bayesian Belief Network to integrate information on the potential effects of water quality mitigation measures, including data and expert opinion, and parameterizations of the uncertainties in these quantities, in a single model. Specifically, the model integrates spatially distributed geographic information system data about land use and crops, soil erosion risk, topographic connectivity, presence of soil drains, soil hydrological leaching and P binding properties, farm yard locations for incidental P losses, sewage treatment works and septic tank location, with catchment rainfall and runoff data, fertiliser application rates and likely buffer effectiveness. Critical source areas of diffuse and point source pollution risk are mapped on 100x100 m raster grids for two pilot catchments in north-east Scotland – Lunan Water (124 km2) and Tarland (72 km2). The model simulates the probability of P concentration falling into the WFD high-good-moderate-poor classification categories at the catchment outlet and models P source apportionment alongside the effectiveness of mitigation measures such as buffer strips and fertiliser application rates.

Sensitivity analysis of the model reveals the importance of hydrology for the seasonal dilution of P concentrations at the catchment outlet. Diffuse point sources, such as incidental losses from farmyards, are also important for this model of P pollution risk, along with sewage treatment works. The presence/absence of soil drains and septic tanks have a smaller influence on the outputs from the model.

The PhosphoRisk decision support tool facilitates system-level thinking about phosphorus pollution and brings together academic and stakeholder communities to co-construct a model structure appropriate to the region it is modelling. The model reveals the causal relationships between the modelled factors driving an understanding of the effects of land use on P pollution risk in Scottish catchments. The modelled scenarios will help to inform and target water quality mitigation measures in high risk areas, while the quantified model uncertainties will inform further research and motivate targeted data collection.

How to cite: Glendell, M., Vinten, A., Richards, S., Gagkas, Z., Lilly, A., Baggaley, N., Coull, M., Schurch, N., Gimona, A., Pohle, I., Troldborg, M., and Stutter, M.: A systems approach to modelling phosphorus pollution risk in Scottish rivers using Bayesian Belief Networks, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-8229, https://doi.org/10.5194/egusphere-egu2020-8229, 2020.

EGU2020-7967 | Displays | HS2.3.1

Modeling Nitrate Export at the Catchment Scale using StorAge Selection Functions

Tam Nguyen, Rohini Kumar, Stefanie R. Lutz, Andreas Musolff, and Jan H. Fleckenstein

Catchments store and release water of different ages. The time of a water parcel remaining in contact with the catchment subsurface affects the solute dynamics in the catchment and ultimately in the stream. Catchment storage can be conceptualized as a collection of different water parcels with different ages, the so-called residence time distribution (RTD). Similarly, the distribution of water ages in streamflow at the catchment outlet, which is sampled from the RTD, is called the travel time distribution (TTD). The selection preferences for discharge can be characterized by StorAge selection (SAS) functions. In recent years, numerical experiments have shown that SAS functions are time-variant and can be approximated, for example, by the beta distribution function. SAS functions have been emerging as a promising tool for modeling catchment-scale solute export.

In this study, we aim to integrate the SAS-based description of nitrate transport with the mHM-Nitrate model (Yang et al., 2018) to simulate solute transport and turnover above and below the soil zone including legacy effects. The mHM-Nitrate is a grid based distributed model with the hydrological concept taken from the mesoscale Hydrologic Model (mHM) and the water quality concept taken from the HYdrological Predictions for the Environment (HYPE) model. Here, we replaced the description of nitrate transport in groundwater from the original mHM-Nitrate with time-variant SAS-based modeling, while we kept the detailed description of turnover of organic and inorganic nitrogen in the near-surface (root zone) from mHM-Nitrate. First-order decay was used to represent biogeochemical (denitrification) processes below the root zone and in the stream. The proposed model was tested in a mixed agricultural-forested headwater catchment in the Harz Mountains, Germany. Results show that the proposed SAS augmented nitrate model (with the time-variant beta function) is able to represent streamflow and catchment nitrate export with satisfactory results (NSE for streamflow = 0.83 and for nitrate = 0.5 at the daily time step). Overall, our combined model provides a new approach for a spatially distributed simulation of nitrogen reaction processes in the soil zone and a spatially implicit simulation of transport pathways of nitrate and denitrification in the entire catchment.

Yang, X., Jomaa, S., Zink, M., Fleckenstein, J. H., Borchardt, D., & Rode, M. ( 2018). A new fully distributed model of nitrate transport and removal at catchment scale. Water Resources Research, 54, 58565877.

How to cite: Nguyen, T., Kumar, R., Lutz, S. R., Musolff, A., and Fleckenstein, J. H.: Modeling Nitrate Export at the Catchment Scale using StorAge Selection Functions, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-7967, https://doi.org/10.5194/egusphere-egu2020-7967, 2020.

EGU2020-22154 | Displays | HS2.3.1

A global synthesis of dual nitrate isotope values in rivers and groundwaters

Ioannis Matiatos and the IAEA Coordinated Research Project on Isotopes to study nitrogen pollution and eutrophication of rivers and lakes

Exponential human population growth and the rapid co-development of agricultural and industrial sectors have caused a sharp increase of nitrogen loading to rivers and groundwaters worldwide since the 1950s. Reactive nitrogen species (e.g., nitrate, ammonium) are widely distributed compounds in rivers and groundwaters primarily as a result of diverse agricultural activities utilizing N-containing fertilizers and anthropogenic non-point sources, such as the disposal of sewage by centralized and individual systems, animal feeding operations, and elevated atmospheric N deposition. Systematic efforts to identify global patterns in nitrogen loss processes using nitrogen isotopes have mostly targeted soil and plant systems but remain rather limited for surface and/or groundwater systems. Here, synthesized published (4,492) and new data (425) for nitrogen and oxygen isotopes of nitrate in rivers and groundwater generated under an IAEA Coordinated Research Project, which aimed to utilize the application of nitrogen isotope techniques to assess nitrogen pollution in rivers and groundwaters, are presented. Among the two water types, we found that groundwater had higher average nitrate concentrations (~5.0 mg L-1 NO3-N) versus rivers (~2.0 mg L-1 NO3-N), slightly higher δ15N and much higher δ18O (+7.6 ‰ and +4.3 ‰, respectively) compared to rivers (+7.0 ‰ and +1.8 ‰, respectively). Seasonal variations in the concentrations and the isotopic compositions of N-species were found to be temperature related, given that biological activity increases with water temperature. Across a range of Köppen climate types, we found the δ15N and δ18O of NO3 in rivers systematically increased when moving from temperate to tropical climates, following the increase of the average air temperature.

How to cite: Matiatos, I. and the IAEA Coordinated Research Project on Isotopes to study nitrogen pollution and eutrophication of rivers and lakes: A global synthesis of dual nitrate isotope values in rivers and groundwaters, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-22154, https://doi.org/10.5194/egusphere-egu2020-22154, 2020.

This study includes water quality monitoring data obtained since June, 2014 at the farm located in the middle part of Latvia. The water treatment system with two separate constructed wetlands was established to improve water quality in agricultural area. A surface flow constructed wetland received drainage runoff from the agricultural catchment basin. A subsurface flow constructed wetland was implemented to retain nutrients from the surface runoff collected in the area of impermeable pavements of the farmyard. As there are no other specific calculations recommended for the designing of constructed wetlands in Latvia, both wetlands were calculated basing on the surface area of the constructed wetland/catchment area ratio. The surface area of the subsurface flow constructed wetland was deigned by 1.2% of the catchment area and the ratio was 0.5 % for the surface flow constructed wetland.

Water samples were collected manually by grab sampling method once or twice per month basing on a flowrate. Water quality parameters such as total suspended solids (TSS), nitrate-nitrogen (NO3-N), ammonium-nitrogen (NH4-N), total nitrogen (TN), orthophosphate-phosphorus (PO4-P), and total phosphorus (TP), biochemical oxygen demand (BOD) and chemical oxygen demand (COD) were analysed to monitor the performance of both wetlands. The concentrations at the inlet and outlet were compared to evaluate the efficiency of the water treatment.

The concentrations of NO3-N, NH4-N and TN were reduced on average by 21 %, 35 % and 20 %, respectively for the surface flow constructed wetland. PO4-P and TP concentrations were reduced on average by 31 % and 45 %, respectively for the surface flow constructed wetland. Total suspended solids were reduced by 17% at the outlet of the surface flow constructed wetland. However, in some cases, an increase in nutrient concentrations in water leaving the wetland was observed. The study showed the constant reduction of the PO4-P and TP concentrations 82 % and 83 %, respectively in the subsurface flow constructed wetland. The concentrations of NO3-N, NH4-N and TN were reduced on average by 14 %, 66 % and 53 %, respectively for the subsurface flow constructed wetland. BOD and COD reduction on average by 93 % and 83 %, respectively in for the subsurface flow constructed wetland indicated the ability of the treatment system to be adapted for wastewater treatment with high content of organic matter under the given climate conditions. This study outlined that the farmyards should receive a special attention regarding surface runoff management.

How to cite: Grinberga, L. and Lagzdins, A.: The improvement of water quality indicators in constructed wetland treatment systems in Latvia, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-12678, https://doi.org/10.5194/egusphere-egu2020-12678, 2020.

EGU2020-225 | Displays | HS2.3.1 | Highlight

Post-fire impact on the water quality of a reservoir: an integrated watershed-reservoir modeling approach

Marta Basso, Marcos Mateus, Tiago Ramos, and Diana Vieira

Wildfires are an increasing threat in the Mediterranean area causing the loss of goods and frequently on the loss of human lives. Not only forest fires are worrisome for their first and visible impacts on vegetation and soil, but also for the secondary impacts on the quality of surface water bodies. Approximately one third of the world’s largest cities obtain their drinking water from forest catchments. The removal of vegetation and consequent increase in runoff with high concentration in sediments often leads to increased nutrients and sediment loads to water reservoirs damaging the aquatic ecosystem and human health.

In Portugal, the catastrophic events of Portuguese territory in 2017 occurred in strategic catchments from the water supply point of view. The Castelo de Bode reservoir, located in that area, with a total capacity of 1095 hm3, supplies the city of Lisbon and surrounding areas (2,000,000 inhabitants). During 2017, more than one hundred thousand hectares of land in the upstream watershed were burned, making it one of the most affected areas in Portugal.

This study focuses on the impacts of the fires on the water quality of Castelo de Bode reservoir. The Soil Water Assessment Tool (SWAT) was first calibrated and validated for simulating streamflow, sediments and nutrients transport. The post-fire impacts were implemented by adjusting land use characteristics (curve number, crop vegetation management factor), and soil properties (soil erodibility), taking into account the different impacts from fire (low, medium, and high severity). The output from this model was then used as input to CE-QUAL-W2 reservoir model. During the calibration phase, it was possible to observe that CE-QUAL-W2 presented some limitations in reproducing water quality parameters, according to the available field measurements in such large reservoir . Therefore, the parameters with the best fit to the measurements at the dam wall were chosen as water quality indicators in the post-fire.

Preliminary results indicated an increase in nutrients and algae concentrations in the year following the 2017 fire events, characterized also by a decrease in the water level due to the base flow reduction at the watershed scale. Although high concentrations of nutrients characterized the reservoir inlet, only phosphate concentration slightly overcame the thresholds limits foreseen in legislation for drinking water close to the dam wall, likely due to the large volume of the reservoir which diluted the inflow concentrations.

How to cite: Basso, M., Mateus, M., Ramos, T., and Vieira, D.: Post-fire impact on the water quality of a reservoir: an integrated watershed-reservoir modeling approach, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-225, https://doi.org/10.5194/egusphere-egu2020-225, 2020.

EGU2020-19842 | Displays | HS2.3.1

Combining Ecohydrological Catchment Modelling and Water Quality Monitoring to Assess Surface Water Pollution in the Swist River Basin

Alexander Ahring, Marvin Kothe, Christian Gattke, Ekkehard Christoffels, and Bernd Diekkrüger

Inland surface waters like rivers, streams, lakes and reservoirs are subject to anthropogenic pollutant emissions from various sources. These emissions can have severe negative impacts on surface water ecology, as well as human health when surface waters are used for recreational activities, irrigation of cropland or drinking water production. In order to protect aquatic ecosystems and freshwater resources, the European Water Framework Directive (WFD) sets specific quality requirements which the EU member states must meet until 2027 for every water body.

Implementing effective measures and emission control strategies requires knowledge about the important emission pathways in a given river basin. However, due to the abundance of pollution sources and the heterogeneity of emission pathways in time and space, it is not feasible to gain this knowledge via water quality monitoring alone. In our study, we aim to combine SWAT ecohydrological modelling and long term water quality monitoring data to establish a spatially differentiated nitrogen emission inventory on the sub-catchment scale. SWAT (short for Soil and Water Assessment Tool) is a semi-distributed, dynamic and process-driven watershed model capable of simulating long term hydrology as well as nutrient fluxes on a daily time step.

The study area is the Swist river basin in North Rhine-Westphalia (Germany). Belonging to the Rhine river system, the Swist is the largest tributary of the Erft River and drains a basin area of approximately 290 km². As part of its legal obligations and research activities, the Erftverband local waterboard collects a large variety of long term monitoring data in the Swist river catchment, which is available for this study. This includes operational data from the wastewater treatment plants in the watershed, discharge data from four stream gauging stations, river water quality data from continuous and discontinuous monitoring, groundwater quality data as well as quality data from surface, sub-surface and tile drainage runoff from various land uses.

Our contribution will be made up of two equal parts: First, we will present our water quality monitoring activities in the catchment and the related data pool outlined above, with special emphasis on recent monitoring results from agricultural tile drainages. Apart from nutrients and other pollutants, the data suggests considerable inputs of herbicide transformation products like Chloridazon-Desphenyl (maximum concentration measured: 15 µg/l) via this pathway. Second, we will explain how we integrate the monitoring data into the SWAT simulations and how we tackle related challenges like parameter equifinality (meaning that multiple parameter sets can yield similar or identical model outputs). The overall goal is to take all possible emission pathways into consideration, including those often neglected in past SWAT studies, like tile drainages and combined sewer overflows (CSO). As the Swist catchment is affected by groundwater extraction due to lignite mining in the Lower Rhine Bay area, we will discuss how this is considered during SWAT model setup and calibration, and will present first simulation results concerning catchment hydrology.

How to cite: Ahring, A., Kothe, M., Gattke, C., Christoffels, E., and Diekkrüger, B.: Combining Ecohydrological Catchment Modelling and Water Quality Monitoring to Assess Surface Water Pollution in the Swist River Basin, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-19842, https://doi.org/10.5194/egusphere-egu2020-19842, 2020.

EGU2020-7854 | Displays | HS2.3.1

Advancing understanding of the importance of surface runoff for delivery of water, sediment, nutrients and pesticides to streams within agricultural catchments

Brian Kronvang, Jørgen Windolf, Henrik Tornbjerg, Sofie van't Veen, Dominik Zak, Niels Ovesen, and Goswin Heckrath

Explicit knowledge of the dynamics and spatial distribution of surface runoff, leaching and preferential flow paths in landscapes and their connections with surface water is critical for protecting the aquatic environment for inputs of sediment, nutrients, pesticides and other harmful substances. Therefore, there is a need for quantifying off-site surface runoff and the resulting transport of sediment, nutrients and pesticides to surface waters at the field scale combined with simultaneous measurements in receiving watercourses to increase our knowledge about the linkages between source areas, transport pathways and the resulting impacts on water quality in receiving water bodies. The importance of surface runoff for transport of sediment, nutrients and pesticides to surface waters have only been limited studied in Denmark even though forecasts of climate change predicts that extreme weather conditions with more intense precipitation events will increase in the future with a risk of having more frequent incidents with surface runoff from agricultural land.

In a recent project soil erosion and surface runoff risks have been modelled for the entire of Denmark on a 10 m x10 m grid scale (Onnen et al., 2019). The influence of surface runoff for transport of sediment, nutrients and pesticides to streams is measured in three carefully selected agricultural mini-catchments showing high risks for having surface runoff in the national model. Within each catchment, an edge of field monitoring site and a stream monitoring station has been established. The edge of field monitoring site consists of a flow chamber collecting surface runoff from the neighbouring field and an automatic sampler initiated at the onset of surface runoff. The edge of field station is established with communication to the stream station for starting an automatic sampler at the time of surface runoff. Selected water samples collected at the edge of field and stream station is analysed for sediment, nutrients and pesticides. A first pilot study from one of the small catchments during the winter of 2015-2016 showed that surface runoff from the field amounted to 48 mm. the loss of suspended sediment, total nitrogen and total phosphorus, respectively, 56 kg sediment ha-1, 0.29 kg N ha-1 and 0.30 kg P ha-1 (Zak et al., 2019). The new edge of field and stream monitoring setup in three agricultural catchments was established during autumn and winter of 2019-2020. The first pilot results from the winter of 2019-2020 with the full monitoring programme in the three catchments have shown frequent surface runoff events and relatively high concentrations of a number of pesticides both in edge of field and stream samples.

 

References

Onnen, N., Heckrath, G., Stevens, A., Olsen, P., Greve, M.B., Pullens, J.W.M., Kronvang, B. and Van Oost, K. 2019. Distributed water erosion modelling at fine spatial resolution across Denmark. Geomorphology 342: 150-162.

Zak, D., Stutter, M., Jensen, H.S., egemose, S., Carstensen, M.V., Audet, J., Strand, J.A., Feuerbach, P., Hoffmann, C.C., Christen, B., Hille, S., Knudsen, M., Stockan, J., Watson, H., Heckrath, G. and Kronvang, B. 2019. An assessment of the multifuntionality of integrated buffer zones in northwestern Europe, JEQ 48: 362-375.

How to cite: Kronvang, B., Windolf, J., Tornbjerg, H., van't Veen, S., Zak, D., Ovesen, N., and Heckrath, G.: Advancing understanding of the importance of surface runoff for delivery of water, sediment, nutrients and pesticides to streams within agricultural catchments, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-7854, https://doi.org/10.5194/egusphere-egu2020-7854, 2020.

EGU2020-8010 | Displays | HS2.3.1

Modelling sub-daily phytoplankton dynamics and analysing primary production controls in the lower Thames catchment, UK

Devanshi Pathak, Michael Hutchins, and François Edwards

River phytoplankton provide food for primary consumers, and are a major source of oxygen in many rivers. However, high phytoplankton concentrations can hamper river water quality and ecosystem functioning, making it crucial to predict and prevent harmful phytoplankton growth in rivers. In this study, we modify an existing mechanistic water quality model to simulate sub-daily changes in water quality, and present its application in the River Thames catchment. So far, the modelling studies in the River Thames have focused on daily to weekly time-steps, and have shown limited predictive ability in modelling phytoplankton concentrations. With the availability of high-frequency water quality data, modelling tools can be improved to better understand process interactions for phytoplankton growth in dynamic rivers. The modified model in this study uses high-frequency water quality data along a 62 km stretch in the lower Thames to simulate river flows, water temperature, nutrients, and phytoplankton concentrations at sub-daily time-steps for 2013-14. Model performance is judged by percentage error in mean and Nash-Sutcliffe Efficiency (NSE) statistics. The model satisfactorily simulates the observed diurnal variability and transport of phytoplankton concentrations within the river stretch, with NSE values greater than 0.7 at all calibration sites. Phytoplankton blooms develop within an optimum range of flows (16-81 m3/s) and temperature (11-18° C), and are largely influenced by phytoplankton growth and death rate parameters. We find that phytoplankton growth in the lower Thames is mainly limited by physical controls such as residence time, light, and water temperature, and show some nutrient limitation arising from phosphorus depletion in summer. The model is tested under different future scenarios to evaluate the impact of changes in climate and management conditions on primary production and its controls. Our findings provide support for the argument that the sub-daily modelling of phytoplankton is a step forward in better prediction and management of phytoplankton dynamics in river systems.

How to cite: Pathak, D., Hutchins, M., and Edwards, F.: Modelling sub-daily phytoplankton dynamics and analysing primary production controls in the lower Thames catchment, UK, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-8010, https://doi.org/10.5194/egusphere-egu2020-8010, 2020.