Presentation type:
HS – Hydrological Sciences

EGU23-1844 | Orals | MAL15 | Henry Darcy Medal Lecture

Global Water Resources and the Limits to Groundwater Use 

Marc Bierkens

Humans have impacted the hydrological cycle since the invention of agriculture, but these impacts have grown to global proportions over the last 60 years. The indirect effects of anthropogenic climate change may be the largest, but the direct impacts by dam building, water withdrawals and the emission of pollutants is still formidable, even by comparison. In the first part of this lecture, I will briefly go over the impacts of human water use on global hydrology and water resources and how these impacts have been assessed by observational evidence and global hydrological models. This will also provide the opportunity to highlight some recent advancements in global hydrological modelling. The second part of the lecture will focus on the impacts of human water use on groundwater resources. After reviewing past assessments of global groundwater depletion rates, I will show results of ongoing research in our group on the limits to global groundwater use. These include: physical limits, related to groundwater-surface water interaction, permeability constraints and salinity; economic limits, related to the costs of groundwater extraction when wells become deeper; and ecological limits, related to the impacts of groundwater extraction on groundwater dependent ecosystems.

How to cite: Bierkens, M.: Global Water Resources and the Limits to Groundwater Use, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-1844, https://doi.org/10.5194/egusphere-egu23-1844, 2023.

EGU23-4076 | Orals | MAL17 | John Dalton Medal Lecture

Evolution of Global Hydrology in the Anthropocene 

Taikan Oki

Until the 1970s, global hydrology had to rely on the collection of in-situ observational data and aggregation under condition when electronic computers were not sufficiently available. In the 1980s, earth observation data from artificial satellites began to observe clouds, precipitation, and later surface soil moisture content, and from the beginning of the 21st century, total terrestrial water storage, including groundwater and ice sheets. Along with this, data assimilation systems merging simulated forecasts by numerical models of the atmosphere and in-situ and satellite observations have been developed, and the information on global hydrologic cycles, at least regarding the atmosphere, has become available.

When we applied the atmospheric water balance method to the four-dimensional data assimilation (4DDA) data and compared it with the discharge of major rivers around the world, we found that the seasonal variation was captured well, although the quantitative accuracy was not sufficient. Seasonal variations in total terrestrial water storage are very large in the Amazon Basin and cannot be explained by changes in soil moisture alone. It was suggested that the changes in river water stored in the river channel contributed greatly, but it was necessary to wait until later GRACE observation data were available to obtain conclusive evidence.

In addition, when the atmospheric water balance method is applied, negative runoff is calculated in some regions and seasons, and at first it was thought to be an error in data and the data processing, and an ad hoc correction method was attempted. However, even from the composite of in-situ discharge data, some areas were found where the downstream river discharge was smaller than the upstream, and negative runoff should be estimated. Then, it became apparent that the negative runoff should be mainly due to anthropogenic water withdrawals and consumption, it is necessary to consider human activities in research targeting the actual water cycle, and such interventions can be detected even on a global scale.

Then, starting with storing in and releasing from reservoirs, an integrated water cycle and water resources model that considers human activities such as water withdrawals from rivers and groundwater, irrigation for farmlands, and long-distance water transport through canals has been developed and used. Although such a model was initially for a global scale, it can be applied for local simulation of hydrologic cycles in the Anthropocene considering water supply and sewerage systems and contribute to supporting scientific evidence-based decision makings.

Improvements in observational and computational capabilities alone did not support the development of global hydrology. In addition to the numerical model itself, it should be acknowledged to the development and sharing of critical global data such as topography, land use and land cover, and cropland distribution equipped for irrigation that are essential for proper simulation of the model. Global hydrology is a community-supported discipline and the gift of grassroots solidarity among researchers around the world.

How to cite: Oki, T.: Evolution of Global Hydrology in the Anthropocene, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-4076, https://doi.org/10.5194/egusphere-egu23-4076, 2023.

EGU23-11454 | Orals | HS5.16 | HS Division Outstanding Early Career Scientist Award Lecture

Groundwater availability and sustainability 

Inge de Graaf

Groundwater is het largest available freshwater resource on earth and is critical to humans and the environment. Groundwater is especially important for irrigated agriculture, and thus for global crop production and food security; approximately 40% of the today’s irrigated agriculture depends on groundwater. In many regions around the world, unsustainable groundwater pumping exceeds recharge from precipitation and rivers. This leads to substantial drops in groundwater levels and losses of groundwater from its storage, especially in intensively irrigated regions, as well as reduction of river flows with possible devastating impacts on freshwater ecosystems.

In my research I simulate groundwater flows and groundwater surface water interactions globally, using a high resolution coupled groundwater and surface water model, and study the impacts of groundwater pumping from the recent past until the far future. In this talk I will present recent findings on current and projected impacts of groundwater pumping on river flows, including an estimate where and when environmentally critical thresholds for groundwater discharge are reached. Second, I will present novel developments and future research steps me and my team will take towards estimating global groundwater availability that can be sustainably exploited and the trade-off between sustainable groundwater use and crop production.

How to cite: de Graaf, I.: Groundwater availability and sustainability, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-11454, https://doi.org/10.5194/egusphere-egu23-11454, 2023.

HS1.1 – Hydrological Sciences for Policy and Society

Accelerated climate, environmental and societal change and its dynamics challenge the resilience of complex socio-ecological systems and require constant adaptation. It also requires to better integrate uncertainties into the decision-making process. By comparing two case studies in Tanzania and Germany with different foci in human-water interaction and socio-political backgrounds, patterns of decision-making under uncertainty are identified. Using a (semi)participatory qualitative system analysis approach helps identifying the heterogeneity of actors and their specific ways of reasoning. For example, in the case studies the perception of change and uncertainty differed between the stakeholders and were identified as important drivers for different decision rationales and hence different preferred adaptation strategies. While research in reducing environmental uncertainty through e.g. improved physical understanding and models is important, it is only on side of the equation in complex socio-ecological systems. Especially, the interplay of environmental and socio-economic uncertainty and how this uncertainty loop creates different rooms of action and agency is worth considering. The comparison shows that acknowledging heterogeneity is important across regions and water management issues and supports in developing tailor-made adaptation strategies targeting the environmental issue. Additionally, the approach empowers and enables actors to increase their room of action and adaptation capacity by acknowledging their uncertainty perception.

How to cite: Höllermann, B.: Impact of interplay of perceived environmental and socio-political uncertainties on adaptation decisions, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-206, https://doi.org/10.5194/egusphere-egu23-206, 2023.

EGU23-409 | ECS | PICO | HS1.1.3

Simulating the effects of sea level rise and soil salinization on migration and adaptation in coastal Mozambique 

Kushagra Pandey, Jens de Bruijn, Hans de Moel, and Jeroen Aerts

Sea level rise (SLR) causes increasing salt deposition in the soil and groundwater of coastal regions. This will affect coastal farmers, since salinity levels will reduce crop yield, which leads to loss in net annual income of farmer communities. To minimize the impacts and income loss, farmers often adopt adaptation measures, such as irrigation, adding manure and gypsum, switching to salt tolerant crops, or buying less saline lands. When these options are not feasible,  farmers may migrate to inland areas to minimize future impacts and damages.

We adopt an agent-based model (ABM) to simulate adaptation and migration decisions by farmers in Mozambique under sea level rise. . The ABM is coupled to a salinization module for simulating the relation between soil salinity and sea level rise. The decision rules in the model (DYNAMO-M) are grounded in economic theory of subjected expected utility where household maximize their welfare by deciding 1) to stay and face loss from salinization and flooding, 2) stay and adapt (irrigation or buy land) or 3) migrate to safer inland areas. The model runs with a yearly timestep (2020-2100) for simulating salinity levels, but accounts for dynamics in the growing season. (Future-) soil salinity levels are derived from ISRIC (2012) and Hassani et al. (2020). Projections in salinity levels are converted into (reduced-) yield levels following Maas and Hoffman (1977). Country statistics and census data are then used to estimate farmers income from expected yields. The model finally simulates adaptation decisions based on the cost (expected yield loss + adaptation investments) against the benefit (expected yield). Results show how many farming households have stayed with the damage, adapted with a measure, and migrated to inland areas over time and space.  

 

Keywords: sea level rise, soil salinization, coastal farmers, agent-based model, migration

How to cite: Pandey, K., de Bruijn, J., de Moel, H., and Aerts, J.: Simulating the effects of sea level rise and soil salinization on migration and adaptation in coastal Mozambique, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-409, https://doi.org/10.5194/egusphere-egu23-409, 2023.

The understanding of floods has become more complex as the changing climate has made the floods more unpredictable, recurrent, and intensified. The present study focuses on the analysis of behavior of the sub-basins under the extreme rainfall events. For this purpose, an extreme flood event of 2019 in Koyna River Basin located in the Upper Krishna River Basin, Maharashtra was considered. The hydrological responses of the sub-basins of Koyna River basin during this flood event were obtained using a Process-based Soil and Water Assessment (SWAT) hydrological model. The model was configured using the topographical, land use, soil and metrological parameters, respectively. Fathom FABDEM hydrologically corrected DEM were used to delineate the watershed with an outlet near Karad City, just downstream of the Warunji gauging station. The Indian Metrological Department (IMD) 0.250 * 0.250 daily gridded rainfall data and minimum and maximum temperature were used to set up the model. The simulation runs were taken to obtain the responses of the sub-basins for the period of 2016 to 2020.  The study reveals high value of Coefficient of Correlation (R2) being equal to 0.72 indicating that the simulated runoff is closely related with the observed runoff at Warunji Gauging station. The configured hydrological model would be useful in predicting the sub-basin responses under climate change so that the proper planning and preparedness can be made to evolve the robust policies for handling severe floods in the future.

Keywords: Climate Change, Extreme events, SWAT, FABDEM, Koyna River.

How to cite: Ranjan, R. and Keshari, A. K.: Process-based Hydrological Modeling to Analyse Sub-basin Response Under Extreme Rainfall Events in Koyna River Basin, Maharashtra, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-1663, https://doi.org/10.5194/egusphere-egu23-1663, 2023.

Climate change and human activities may cause change points in hydrological processes, which have serious impacts on the stability of watershed hydrological ecosystems. The Pettitt test method was used to identify the change point of discharge in the Yangtze River basin, and ecological water demand was estimated based on generalized extreme value distribution. The results show that: (1) the ecological water demand guarantee rate of the Yangtze River basin increased from a viewpoint of the whole basin during the past decades, especially in dry seasons. Due to the regulation of reservoirs and dams in the Yangtze River Basin, the ecological surplus (ecological deficit) tends to increase (decrease) in the dry season of the Yangtze River Basin, while it tends to reverse in the wet season. (2) The degree of hydrological alterations in the trunk stream of the Yangtze River Basin is the highest (D0 reaches 50% or more), and the river hydrological situation and ecosystem are under high risks (the total DHRAM score is more than 10 points), and the biodiversity shows a significant downward trend. (3) Climate change and human activities have the opposite impact on ecological streamflow of the Yangtze River Basin, that is, climate change increases ecological surplus and decreases ecological surplus. Overall, climate change is the leading factor affecting ecological surplus (the contribution is more than 50%).

How to cite: he, Y. and gu, X.: Ecological Instream Flow in the Yangtze River Basin under the Hydrological Change: Changes, Impacts, and Attributions, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-2070, https://doi.org/10.5194/egusphere-egu23-2070, 2023.

EGU23-2256 | ECS | PICO | HS1.1.3 | Highlight

Influence of urbanization on flood extent changes at the global level 

Maurizio Mazzoleni, Francesco Dottori, Hannah L. Cloke, and Giuliano Di Baldassarre

Anthropogenic actions are progressively affecting most river basins worldwide, resulting in changes in hydrological processes and thus influencing water availability. Despite previous studies aimed at quantifying the relationship between urbanization and extreme flooding events at local to regional scales, it is still unclear how human presence has influenced the occurrence of seasonal surface water. As a result, global patterns remain largely unknown.

In this study, we perform a global analysis of large river basins and uncover global trends of annual maximum flood extent and impervious area, as well as their relationships with rainfall and snowmelt, over the past three decades. Hydrological and urban dynamics are computed by using multiple earth observation datasets.

We find that hydroclimatic variability alone cannot explain changes in annual maximum flood extent for 75% of the analyzed river basins worldwide. We also observe increasing trends in both annual maximum flood extent and the urbanized area within floodplains, especially in Asian and African river basins. Our findings reveal an emerging global reciprocal relationship between urbanization processes and maximum flood extent changes. Both rainfall and urbanized area can explain changes in the annual maximum flood extent in 57% of the analyzed basins.

Our findings highlight the need for a better understanding of the influence of human presence on changes in seasonal water dynamics at the global scale. In view of the worldwide rapid development of urban areas, these findings can inform the process of flood risk management and help improve targeted policy and land use interventions

How to cite: Mazzoleni, M., Dottori, F., Cloke, H. L., and Di Baldassarre, G.: Influence of urbanization on flood extent changes at the global level, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-2256, https://doi.org/10.5194/egusphere-egu23-2256, 2023.

For governing river basin systems, social-ecological systems (SES) structures can be reshaped by institutions, such as policies, laws, and norms. Effective (“matched” or “fit”) institutions operate at appropriate spatial, temporal, and functional scales to manage and balance different relationships and interactions between human and water systems, supporting (but not guaranteeing) the sustainability of SES. To better understand how water governance institutions match/mismatch their social-ecological context, we take the Yellow River Basin (YRB), China, as an example to dive into causal links between institutional changes and outcomes. An agent-based model was developed around the Yellow River's most far-reaching water quota institution during the past half century, considering how factors such as human behaviour and environmental change have combined with the institutional shifts to lead to changes in the Yellow River's water use. Our results show regional differences in the impact of the system, with some areas tending to ignore the constraints of the quota system when other provinces embarked on a water-saving transition. Our model demonstrates the dramatic impact of institutional change on socio-hydrological processes and has guidness for the sustainable use of water resources at a time when non-engineered measures of water governance are becoming increasingly common.

How to cite: Song, S., Wang, S., and Fu, B.: Institutional impacts on the evolution of the Yellow River, China: a perspective from socio-hydrological modelling, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-4221, https://doi.org/10.5194/egusphere-egu23-4221, 2023.

EGU23-4575 | PICO | HS1.1.3

Management and restoration of the mining maquis ecosystem in New Caledonia (South West Pacific) 

Michel Allenbach, Agnes Semper, and Claire Cote

New Caledonia is a French overseas territory located in the southwest Pacific, 2000 km east of Australia. Geologically, the Antarctic and Australian plates broke up 250 Ma ago as a result of the break-up of Gondwana land. Ocean basins opened up and remnants of the former supercontinent separated and drifted eastwards. The eastern ridge, known as Norfolk ridge, substratum of New-Caledonia sank under the water. The New Caledonian Great Land emerged 34 million years ago after obduction phase. A new terrestrial environment was created. Freshly emerged, it was gradually recolonized by animals and plants from more or less nearby land masses.

New Caledonia’s Island isolation and the particularity of its soils forced the biotope to adapt and develop original, even unique, characteristics, thus contributing to making it one of the world's champions of biodiversity. With 76% plant endemism, this tiny territory (<20,000 km2) ranks third in the world (behind Hawaii and NZ).

The peridotites brought to the surface by obduction developed a thick alteration profile. Nickel and Cobalt, issued from the primary minerals of the peridotites, got concentrated in the saprolite horizon. The exploitation of these ores, was accelerated after the Second World War with the mechanization of extraction. Carried out without precaution, this time-period resulted in very significant environmental damage: deforestation and soil exposure, accelerated erosion, watercourse siltation and hypersedimentation, and flooded low-lying valleys. 

Environmental awareness was finally raised in the 1970s and increasingly triggered the introduction of responsible regulations. The mining and metallurgy companies working in the area, which are among the world's major players, have significantly improved their operational procedures, the quality of their environmental monitoring and remediation methods

On steep slopes and in a climate where rainfall can be very heavy, water management is one of the challenges to be overcome, as well as the revegetation of workings and slopes. This paper will present the results of the audit carried out by the GEME (mine water management and environment) program of the CNRT "Nickel and Environment" (National Technological Research Centre) on these issues and their comparison, based on the benchmark carried out with those of other major mining countries. The results concern the hydro-sedimentary models used, the acquisition of the parameters introduced, the adequacy with the rules of good practice and the evolution of these rules with global changes as well as the effectiveness of water management and revegetation methods.

The increasing involvement of local populations in the environmental management of the sites affected by mining will be discussed. Most of the mines are located on customary land whose inhabitants are now severely impacted by the mistakes of the past and want to become key players of the mine of the future. In a sensitive political context (end of the Nouméa Accord) where the institutional future of the country has not yet been determined, the topic of nickel mining and its environment is one of the levers for a hoped-for end to the crisis. Our communication will mention this in its conclusion.

How to cite: Allenbach, M., Semper, A., and Cote, C.: Management and restoration of the mining maquis ecosystem in New Caledonia (South West Pacific), EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-4575, https://doi.org/10.5194/egusphere-egu23-4575, 2023.

EGU23-4932 | PICO | HS1.1.3

Panta Rhei benchmark dataset: socio-hydrological data of paired events of floods and droughts 

Heidi Kreibich and the Flood and drought paired event community

Damage due to hydrological extremes increase in many regions of the world. A better understanding of the drivers of increasing damage trends is essential for effective flood and drought risk management. However, empirical data is lacking about the processes in complex human-water systems that result in flood and drought damage. We present a benchmark dataset containing socio-hydrological data of paired events, i.e., two floods or two droughts that occurred in the same area. The 45 paired events cover a wide range of socio-economic and hydro-climatic conditions. The dataset is unique in covering both floods and droughts, in the number of cases assessed, and in the quantity of qualitative and quantitative socio-hydrological data. The core of the benchmark dataset comprises: 1) detailed review style reports about the events and key processes and changes between the two events of a pair; 2) an overview table of key data about management, hazard, exposure, vulnerability and impacts of all events; 3) a table of indicators of change between first and second event of each pair. The advantages of the dataset are that it enables comparative analyses across all the paired events and allows for detailed context- and location-specific assessments based on the extensive data and reports of the individual study areas. A first analysis of the dataset revealed the general pattern that risk management normally reduces the impacts of floods and droughts, but faces difficulties in reducing the impacts of unprecedented events of a magnitude not experienced before (Kreibich et al. 2022a). The dataset can be used by the scientific community for exploratory data analyses and for the development of socio-hydrological models. As such, the dataset can support solving one of the twenty-three unsolved problems in hydrology (Blöschl et al. 2019), namely “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?”. The dataset is available to the public through the GFZ Data Services (Kreibich et al. 2022b).

 

References

Blöschl, G., Bierkens, M. F., Chambel, A., et al. (2019): Twenty-three unsolved problems in hydrology (UPH) – a community perspective. - Hydrological Sciences Journal - Journal des Sciences Hydrologiques, 64, 10, 1141-1158. https://doi.org/10.1080/02626667.2019.1620507

Kreibich, H., Loon, A. F. V., Schröter, K., et al. (2022a): The challenge of unprecedented floods and droughts in risk management. - Nature, 608, 80-86. https://doi.org/10.1038/s41586-022-04917-5

Kreibich, H., Schröter, K., Di Baldassarre, G., et al. (2022b): Panta Rhei benchmark dataset: socio-hydrological data of paired events of floods and droughts. https://doi.org/10.5880/GFZ.4.4.2022.002

How to cite: Kreibich, H. and the Flood and drought paired event community: Panta Rhei benchmark dataset: socio-hydrological data of paired events of floods and droughts, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-4932, https://doi.org/10.5194/egusphere-egu23-4932, 2023.

EGU23-4956 * | ECS | PICO | HS1.1.3 | Highlight

Key drivers and pressures of water scarcity at global hotspots 

Myrthe Leijnse, Bram Droppers, Marc Bierkens, and Niko Wanders

Although global freshwater resources are vital to the livelihood of humanity and all other life on Earth, 10% of the global population lives in regions with high to critical levels of water stress. In many of these regions the freshwater resources risk depletion of surface water or groundwater resources due to unsustainable use. Such regions are considered as the “hotspots of water scarcity”. Understanding how these hotspots have evolved over time towards their current state of water scarcity, provides important insights for decision-making and implementation of mitigation and water regulation policies.

We present a global intercomparison of the key drivers and pressures causing water scarcity at these hotspots around the world. For our analysis we have applied a Driver-Pressure-State-Impact-Response (DPSIR) framework to a literature search of >175 case studies of the hotspot regions. In this framework natural, social and economic information is combined to identify driving forces and resulting pressures that have deteriorated the state (quality or quantity) of the water resources. The DPSIR literature analysis is supported by observational data analysis to study the temporal evaluation for each hotspot.

We identify the key drivers and pressures to be: hydroclimatic changes (78%), population growth (28%) and agricultural (93%), municipal (54%), and industrial water demand (37%). Subsequent impacts on society are less homogeneous between the hotspots, with damage to ecosystems (25%) and reduced agricultural production (16%) as main impacts. Responses also vary greatly. While some have a positive impact on alleviating water scarcity (e.g. increased storage capacity (25%) or water treatment (23%)), others are ineffective in attempting to alleviate water scarcity or even worsen water scarcity problems (e.g. lack of groundwater regulation policies (12%) or unfair distribution of water rights (12%)).

These outcomes of the DPSIR analysis provide valuable information for constructing causal networks representative to water scarcity problems at the hotspots. Such a causal network will serve as the basis of a conceptual model that represents human-water interactions at the hotspots, thereby providing a better understanding of trade-offs and synergies in different human-water systems around the world.

How to cite: Leijnse, M., Droppers, B., Bierkens, M., and Wanders, N.: Key drivers and pressures of water scarcity at global hotspots, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-4956, https://doi.org/10.5194/egusphere-egu23-4956, 2023.

EGU23-5319 | ECS | PICO | HS1.1.3 | Highlight

Humans, Water, and Climate change – Global analysis of Conflicts and Cooperation and their Potential Drivers 

Elisie Kåresdotter, Siyuan Li, Haozhi Pan, and Zahra Kalantari

Despite agreement that climate change is increasingly recognized as a threat multiplier in conflict pathways, connections between water flows and conflicts remain unclear. This is affected by incomplete datasets on water-related conflict-cooperation events and poor understanding of socioeconomic and biophysical causes of such conflicts. Disentangling various drivers of water-related cooperation and conflict pathways, with more complete datasets on water-related conflict-cooperation events and a detailed understanding of socio-economic and biophysical causes of such conflicts, is necessary for resolving conflicts and building peace As part of this study we have complied a new global dataset on water-related conflict-cooperation events that extends to 2019, updating previous datasets that covered only up to 2008, yielding important new insights on cooperation-conflict trends. Correlations between events and aspects such as changes in precipitation and socioeconomic variables were then calculated for different change scenarios. Analysis of events shows that cooperation can significantly reduce future conflicts in all tested change scenarios. In addition, cooperation positively affects countries’ socioeconomic development, further reducing the risk of conflict. The new dataset revealed a worrying trend with a shift in the cooperation-conflict balance in the 2000s, with conflict events increasing and outnumbering cooperation events in 2017. Regional analysis shows that changes towards more conflict and fewer cooperation events in Africa could be related to long periods of drought, while changes in Asia are related to irrigation and dam construction. This study shows that water cooperation can be effective for peacekeeping while simultaneously creating positive socio-economic development. The trend towards less cooperation and more conflict in current years highlights the need for effective water management adapted to local and regional drivers of change (climate or anthropogenic) focusing on forming collaborations based on current and projected water availability. Utilizing our newly created and openly available water-related conflict and cooperation database can provide a good opportunity for further research into actions required to change this trend and promote future water cooperation.

Keywords: conflict; cooperation; peacekeeping; climate change; hydrology;

How to cite: Kåresdotter, E., Li, S., Pan, H., and Kalantari, Z.: Humans, Water, and Climate change – Global analysis of Conflicts and Cooperation and their Potential Drivers, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-5319, https://doi.org/10.5194/egusphere-egu23-5319, 2023.

EGU23-5799 | ECS | PICO | HS1.1.3

A novel way of identifying agricultural water drainage systems and their impact on catchment hydrology 

Estifanos Addisu Yimer, Fatima-Ezzahra Riakhi, Shahla Yadollahi, Imeshi Weerasinghe, Charlotte Wirion, Ryan T. Bailey, Jiri Nossent, and Ann van Griensven

Water drained from agricultural lands is getting more attention as its valuable water is lost from groundwater storage. The historical location of buried agricultural water drainage systems is not known very well. Hence, first, finding the location of those infrastructures is critical. Several methods have been applied in the past, including decision tree classification (DTC), remote sensing based, using radar, etc. However, all the methods neglect the primary cause of the drain application, which is groundwater. Hence, a novel approach is introduced that considers groundwater in the identification procedure. We used two case studies for drain identification, one from Ontario, Canada, and another from Belgium. Furthermore, a physically based and fully distributed modeling approach (SWAT+gwflow) is conducted to investigate the impact of these drainage systems in the catchment hydrology of the Kleine Nete watershed, Belgium.

The result of the drainage system identification has indicated the pitfalls of the already existing methods where accuracy as low as 17% was recorded. On the other hand, the additional filtering based on groundwater head enables us to find an additional 19.4 km2 area. Therefore, the use of groundwater level as an additional filtering technique is vital for increasing the accuracy of tile drain/ditch network identification. Next, drains have been shown to affect hydrology, where a 15% decrease in groundwater evapotranspiration, a 50% reduction in groundwater saturation excess flow, and a 39% decline in groundwater discharge to streams are observed.

How to cite: Yimer, E. A., Riakhi, F.-E., Yadollahi, S., Weerasinghe, I., Wirion, C., T. Bailey, R., Nossent, J., and van Griensven, A.: A novel way of identifying agricultural water drainage systems and their impact on catchment hydrology, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-5799, https://doi.org/10.5194/egusphere-egu23-5799, 2023.

The water cycle is highly interconnected; water fluxes in one part depend on physical and human processes throughout. For example, rivers are a water supply, a receiver of wastewater, and an aggregate of many hydrological, biological, and chemical processes. Thus, simulations of the water cycle that have highly constrained boundaries may miss key interactions that create unanticipated impacts or unexpected opportunities. Integrated environmental models aim to resolve the issue of boundary conditions, however they have some key limitations, and we find a significant need for a parsimonious, self-contained suite that is accessible and easy to setup. With this in mind, we have developed the WSIMOD – a Python package that allows for the representation of the water system’s demands and impacts of multiple sectors and actors’ decisions within a single tool, which is considered beneficial to increasing a shared understanding of system performance and for more collaborative and coherent decisions on integrated water resources, water quality and flood management. The WSIMOD is a self-contained software package that includes modelled representations of key physical and infrastructure elements of the water cycle (urban and rural), with each type of modelled element generically described as a component. Components are written in such a way that any component can interact with any other component. This enables a flexible representation of a water system that is needed to accommodate the wide variety of different built/natural infrastructure configurations and scales. We will showcase how the WSIMOD tool has been developed and successfully tested through a range of applications in the UK, including integrated analysis of urban water systems, catchment water management and urban water neutrality.  

How to cite: Mijic, A., Liu, L., and Dobson, B.: Water Systems Integrated Modelling framework (WSIMOD): A Python package for simulating human-impacted water quality and quantity, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-6399, https://doi.org/10.5194/egusphere-egu23-6399, 2023.

EGU23-7949 | ECS | PICO | HS1.1.3 | Highlight

Quantifying lifetime water scarcity 

Inne Vanderkelen, Édouard Davin, Jessica Keune, Diego G. Miralles, Yoshihide Wada, Hannes Müller-Schmied, Simon Gosling, Yadu Pokhrel, Yusuke Satoh, Naota Hanasaki, Peter Burek, Sebastian Ostberg, Luke Grant, Sabin Taranu, Matthias Mengel, Jan Volkholz, and Wim Thiery

Water scarcity is a growing concern in many regions worldwide, as demand for clean water increases and supply becomes increasingly uncertain under climate change. Already today, more than 4 billion people experience water scarcity at least one month per year (Mekonnen and Hoekstra, 2016). Developing socio-economic conditions and growing population increase water demands, while climate change leads to changes in freshwater availability. Most studies quantify water scarcity in discrete time windows, with fixed population and climate change signals (e.g., 30 years or long-term averages). Recently, however, Thiery et al. (2021) proposed a novel approach, in which climate change impacts are integrated over a person's lifetime. In this cohort perspective, lifetime impact values are comparable across generations and regions. Evaluating this perspective for natural hazards, they showed, for example, that a newborn will experience a sixfold increase in drought exposure compared to a 60-year-old (Thiery et al., 2021). 

In this study, we use this cohort perspective to study how much water scarcity a person experiences during their lifetime. Based on monthly fluctuations in water demand and availability, we estimate the total amount of water demand not met and refer to it as 'lifetime water deficit'. To this end, we use an ensemble of four global hydrological models (MATSIRO, CWatM, LPJmL and H08), each forced by four GCMs and two RCP scenarios from the InterSectoral Impact Model Intercomparison Project (ISIMIP2b). The simulations account for varying population and socio-economic conditions in the historical and future period, following the SSP2 scenario. Combined with country-based population, cohort distribution and life expectancies, lifetime water deficits are quantified for different generations on a country level. 

Our findings reveal high water lifetime deficit values for regions that are already water scarce today, such as the Mediterranean, North Africa and the Middle East. In these regions, more than 70% of the lifetime water demand is not met when needed. Further comparison reveals differences in spatial, intergenerational and climate change scenarios, and provides information on different scenarios. Overall, this study provides a new perspective on quantifying water scarcity and the climate and population impacts. 

References:

Mekonnen, M. M., & Hoekstra, A. Y. (2016). Four billion people facing severe water scarcity. Science Advances, 2(2). https://doi.org/10.1126/sciadv.1500323

Thiery, W., Lange, S., Rogelj, J., Schleussner, C. F., Gudmundsson, L., Seneviratne, S. I., Andrijevic, M., Frieler, K., Emanuel, K., Geiger, T., Bresch, D. N., Zhao, F., Willner, S. N., Büchner, M., Volkholz, J., Bauer, N., Chang, J., Ciais, P., Dury, M., … Wada, Y. (2021). Intergenerational inequities in exposure to climate extremes. Science, 374(6564), 158–160. https://doi.org/10.1126/science.abi7339

How to cite: Vanderkelen, I., Davin, É., Keune, J., Miralles, D. G., Wada, Y., Müller-Schmied, H., Gosling, S., Pokhrel, Y., Satoh, Y., Hanasaki, N., Burek, P., Ostberg, S., Grant, L., Taranu, S., Mengel, M., Volkholz, J., and Thiery, W.: Quantifying lifetime water scarcity, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-7949, https://doi.org/10.5194/egusphere-egu23-7949, 2023.

EGU23-7977 | PICO | HS1.1.3

Managing complex social-hydrological systems for water security: the case of the mountain cryosphere 

Fabian Drenkhan, Wouter Buytaert, Jonathan D. Mackay, Nicholas E. Barrand, David M. Hannah, and Christian Huggel

In many mountain regions, the cryosphere is a crucial component of water provision to downstream societies, as it contributes to dry-season flows and sustains diverse ecosystems. However, many of the world’s glacierized watersheds experience far-reaching changes at accelerated pace due to declining glaciers and snowpack, climate change impacts and socioeconomic development in the non-cryospheric parts of the catchment. The implications for downstream water supply are therefore manifold and complex. Coupled effects of reduced and less reliable water availability, changes in water quality, and growing water demand exert increasing pressure on water resources and threaten future water security and management.

We argue that the limited understanding of interactions between the cryosphere, glacial and non-glacial water stores, river runoff and people hamper climate change adaptation and long-term water security. Meaningful assessments of mountain water security require therefore a holistic social-ecological perspective that interlinks the wider catchment hydrology considering both, surface and subsurface stores, and people including human water demand with improved data and process understanding. Water security assessments can then be guided by a fully coupled hydrological risk framework. This approach needs to integrate multiple social-ecological vulnerabilities as well as the degree of exposure to water shortage under a variety of possible future scenarios of glacier shrinkage, catchment alteration and socioeconomic development. Essentially, this requires a thorough understanding of interrelated upstream-downstream systems and the spatiotemporal propagation of meltwater through the terrestrial water cycle.

Improved data and more diverse knowledge collection that point to the missing links in the terrestrial water cycle are a priority. Multiple sources of knowledge should be co-produced and integrated into a collaborative science-policy-community framework, ideally from the early stages of research planning with attention to local practices and governance. This approach can support a wide set of incremental and transformational strategies that guide robust, locally tailored and effective adaptation pathways. These may include, among other, exploring catchment-specific benefits of nature-based solutions to increase the buffer function of wider catchment hydrology against water loss from glacier shrinkage to enhance long-term water security.

How to cite: Drenkhan, F., Buytaert, W., Mackay, J. D., Barrand, N. E., Hannah, D. M., and Huggel, C.: Managing complex social-hydrological systems for water security: the case of the mountain cryosphere, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-7977, https://doi.org/10.5194/egusphere-egu23-7977, 2023.

Panta Rhei was launched in 2013 with the purpose of reaching “an improved interpretation of the processes governing the water cycle by focusing on their changing dynamics in connection with rapidly changing human systems.” When the idea of Panta Rhei was conceived socio-hydrology was still in its infancy and global warming was about 0.3 degree centigrade lower than today. The subsequent evolution of the research agenda and environmental change proved that Panta Rhei was a brilliant intuition. By building on the IAHS history and legacy, the idea of Panta Rhei catalysed the feeling that change in hydrology and society was an emerging reason of concern and therefore a fascinating field of research. Panta Rhei achieved a major target: by putting together an interdisciplinary community of researchers – mostly early career ones – it set the theoretical basis for an improved understanding of the complex interaction between water and humans. On the other hand, challenging research questions are still unresolved. I had the fortune of chairing the scientific consultation that led to shaping Panta Rhei. I also had the privilege of attending several phases of the Panta Rhei adventure. With this presentation I would like to offer my perspective on the fascinating interplay between water and humans and the achievements and future evolution of Panta Rhei.

How to cite: Montanari, A.: Everything still flows: achievements and future evolution of Panta Rhei, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-8104, https://doi.org/10.5194/egusphere-egu23-8104, 2023.

EGU23-8612 | ECS | PICO | HS1.1.3

Drought and flood risk in Kitui, Kenya: are they increasing and why? 

Marlies H. Barendrecht, Ruben V. Weesie, Tim S. Busker, Alessia Matanó, Maurizio Mazzoleni, and Anne F. van Loon

During the past years, the county of Kitui in Kenya, has experienced severe droughts. Both the short rain season, in March, April and May and the long rain season, in October, November and December have failed for several years in a row. This has had devastating impacts, leading to widespread water and food insecurity. According to local people, the rain seasons have changed over the past years, thereby increasing drought risk. At the same time, flash floods, destroying farmland and water infrastructure are reported to have increased as well. We investigate whether drought and flood risk in Kitui, Kenya, have increased over the past years and what the role of climate, hydrology and humans is in this increase. In addition, we investigate whether droughts are influencing flood risk and vice versa.

How to cite: Barendrecht, M. H., Weesie, R. V., Busker, T. S., Matanó, A., Mazzoleni, M., and van Loon, A. F.: Drought and flood risk in Kitui, Kenya: are they increasing and why?, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-8612, https://doi.org/10.5194/egusphere-egu23-8612, 2023.

EGU23-9040 | PICO | HS1.1.3 | Highlight

The World Water Map of water scarcity hotspots 

Niko Wanders, Myrthe Leijnse, Bram Droppers, Barry van Jaarsveld, Jannis Hoch, Jonas Götte, and Marc Bierkens

The World’s water resources are under severe pressure as a result of unsustainable exploitation and rapidly changing hydroclimatic conditions. In the National Geographic World Water Map project, we combine state of the art hydrological modelling expertise, with storytelling expertise from National Geographic. The World Water Map aims to shed new light on water problems in the world.

In this project we identify 17 hotspots of water scarcity based on state-of-the-art large-scale hydrological modelling results. For the so called “hotspots” we analyze which policies, regulations and climatic changes have resulted in the development of these areas under pressure. We do this by using a literature study of over 175 scientific publications, which helps to identify the drivers and pressure as well as their impact and response for each hotspot. This information is then all included in the online Water Map that provides the general public, policy makers and peers in science with this information. The map consists of an interactive web portal where we tell the untold stories of water scarcity, support water scarcity literacy so that people understand the problems surrounding water scarcity, and provide an interactive platform where people can identify the vulnerability of their local neighbourhoods.

By combining science and storytelling we can shed light on “hotspots” as well as provide the untold stories in these regions. Together with the local and national policymakers we aim to provide much needed open information on pathways forward and future outlooks for “hotspots” around the world.

How to cite: Wanders, N., Leijnse, M., Droppers, B., van Jaarsveld, B., Hoch, J., Götte, J., and Bierkens, M.: The World Water Map of water scarcity hotspots, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-9040, https://doi.org/10.5194/egusphere-egu23-9040, 2023.

The analysis of the factors driving the exploitation of drinking-water sources is fundamental in the modelling and planning of water supply systems. To this end, it is important to assess the impacts of water scarcity, related to periods of hydrological drought, on the use of the available sources. This is of particular interest in touristic regions, where resource management must necessarily take into account also the significant seasonal fluctuation of urban demand.

As part of the European project SIMTWIST (Simulating Tourism Water Consumption with Stakeholders), the study analyses the factors influencing both the demand for drinking-water supply of the city of Rimini and the apportionment of the supply among the different sources available to the water manager (RomagnaAcque-Società delle Fonti SpA). In fact, the city is supplied with both surface water, from the Ridracoli reservoir in the Apennines, and groundwater from well fields on the alluvial fans of the Marecchia and Conca rivers.

The drivers include socio-economic variables (tourist attendance), climatic variables and hydrological availability. In particular, it is analysed how the exploitation of the groundwater source varies as a function of water availability at the Ridracoli reservoir, characterizing such availability through meteorological and hydrological drought indices computed on the upstream catchments.

The analysis, in addition to confirming how the management of the resource cannot, in Mediterranean regions, disregard tourism factors, helps to understand the link between hydrological droughts, governing the availability of river-fed reservoir supply, and the choices made by water managers in the exploitation of the groundwater sources.

How to cite: Toth, E. and Neri, M.: Drinking-water supply sources and hydrological droughts: influence of tourism demand and reservoir availability on groundwater exploitation for the Rimini case study, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-9402, https://doi.org/10.5194/egusphere-egu23-9402, 2023.

EGU23-11579 | ECS | PICO | HS1.1.3

The dynamics of floodplain urbanization and hydraulic engineering development 

Peirong Lin, Shang Gao, Zhenzhong Zeng, Jida Wang, Kaihao Zheng, Ziyun Yin, Zimin Yuan, Zhou Huang, Xudong Zhou, and Xiangyong Lei

Floodplain urbanization is accelerating at an alarming rate in recent decades, which has posed grand challenges to flood risk management. Hydraulic engineering infrastructure is often co-developed alongside this acceleration to mitigate flood risks, but to what extent this co-development matches up with the floodplain urbanization rate needs to be better quantified. In this study, we leverage a range of multi-source geospatial datasets including high-resolution floodplain maps, urban impervious area maps, global dam/reservoir datasets, and flood fatality data from the Emergency Events Database (EM-DAT) to assess the dynamics of floodplain urbanization (1985–2015) and its interplay with hydraulic engineering development at the global scale. We will report our assessments at both the basin level and the country level to promote the understanding of the hydroclimatic and socioeconomic contexts of floodplain urbanization. Ultimately, results from this study are expected to inform the prioritized regions for flood risk mitigation.

How to cite: Lin, P., Gao, S., Zeng, Z., Wang, J., Zheng, K., Yin, Z., Yuan, Z., Huang, Z., Zhou, X., and Lei, X.: The dynamics of floodplain urbanization and hydraulic engineering development, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-11579, https://doi.org/10.5194/egusphere-egu23-11579, 2023.

EGU23-11797 | PICO | HS1.1.3

Potential applications of the Benford’s Law for the investigation of hydrological time series alteration 

Alessio Domeneghetti, Letizia Caroscio, and Serena Ceola

The Benford’s Law, outlined in 1938, estimates the expected frequency of the significant first or first two digits of a time series of a generic variable based on a logarithmic pattern. Lower digits (i.e., 1, 2…) are expected to occur with frequencies higher than those associated to numbers with higher first digits (i.e., 8, 9). According to this law digit 1 typically occurs about 30% of the time, while 9 appears as significant first digit in less than 5% of the cases. The validity of Benford’s Law has been proven for a wide variety of data sets and in different contexts (e.g., public elections, false accounting detection, street addresses, stock and house prices, population numbers), among which few of hydrological relevance: lengths of rivers, river flow series, lake and wetlands extents. Nonconformity of hydrologic data sets to Benford’s Law could be a consequence of time series alteration and thus a signal of the presence of biases or errors, data modification, as well as of the fact that the sample is not fully representative of the variable or the series is affected by external drivers (e.g. anthropic alteration of the natural dynamics).

In this work we referred to more than 1200 GRDC sites to test the Benford’s Law validity over stream flow series longer than 40 years, as well as on the longest stream flow series (more than 12 million of data). Streamflow records have been investigated in parallel to other hydrological relevant datasets that serve as proxy for quantifying the potential human impact (e.g., GRanD-Global Reservoir and Dam Database, FFRs-Free Flowing Rivers). Results of this study, together with those of previous investigations (Nigrini and Miller, 2007) advocate that large hydrological data set should conform the Benford’s Law. On the contrary, the nonconformity to it might highlight data integrity and authenticity issue, or reveal alterations of the natural variability due to human activities or other driving factors (perhaps climate change).

How to cite: Domeneghetti, A., Caroscio, L., and Ceola, S.: Potential applications of the Benford’s Law for the investigation of hydrological time series alteration, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-11797, https://doi.org/10.5194/egusphere-egu23-11797, 2023.

EGU23-12379 | PICO | HS1.1.3

Study on long-term variation of river water quality in Japan 

Koji Kodera, Masato Oda, Yoshihiro Igari, and Yoichi Morimoto

1.introduction

During Japan's period of rapid economic growth, water pollution became a problem throughout the country, but water quality has improved rapidly thanks to the enactment of laws and the heightened environmental awareness of society as a whole. However, even now, not only is the concentration concentrated in Tokyo, but urbanization is also progressing in rural areas, and there are still areas with severe water pollution in the suburbs. What used to be point source pollution has spread to non-point source pollution. Due to problems with wastewater treatment facilities in mountainous areas, many large river basins are more polluted upstream than downstream. The results of the ``Survey of the Water Environment in Public Water Areas,'' which has been continued by the government since 1971, and the ``National Simultaneous Survey of Familiar Water Environments,'' which was started in 2004 by citizens' groups, are available on a nationwide scale. I have mainly studied long-term changes in river water quality in Japan. We will also consider the results of measurements by Hosei University in 2020 and 2021.

2.Results and considerations

1)Water quality survey results for public water areas

There were about 1,000 observation points in 1971, but 15 years later, in 1986, the number exceeded 5,000, and since then observations have continued at just under 6,000 points. In 1971, half of the BOD values were 3 or more, but in 1976 half were 2 or less, and recently, 2 or less accounted for about 80% (2018). The number of points with 1 to 4 remained unchanged, but 4 or more decreased, and 1 or less increased to about half of the total.

2)Nationwide Simultaneous Survey of Familiar Water Environment

In 2004, when the survey began, there were about 2,500 sites, but in 2005 there were about 5,000 sites, and after that, although it remained around 6,000 sites, it reached about 7,000 sites in 2018. COD4 or less is about half.

3.conclusion

In addition to the nationwide long-term observation results, data from before 1971 were collected and organized in an attempt to reconstruct past water quality. With regard to recent water quality, we independently conduct observations at more than 1,500 points nationwide every year to clarify the current situation. In addition to the coastal area in 2020, we were able to investigate the inland area in 2021 and the municipality unit in 2022. We would like to improve the accuracy while continuing the wide-area survey.

How to cite: Kodera, K., Oda, M., Igari, Y., and Morimoto, Y.: Study on long-term variation of river water quality in Japan, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-12379, https://doi.org/10.5194/egusphere-egu23-12379, 2023.

EGU23-12572 | ECS | PICO | HS1.1.3

Reaching SDGs 6.1 and 6.2 in Kazakhstan: State - society relations 

Kamshat Tussupova and Aibek Zhupankhan

Science - policy - society Nexus is important in achieving Sustainable Development Goals (SDG). The current scientific knowledge is sufficient to allow us to implement the best of knowledge to cover the basic needs such as access to safe water and sanitation; however, the implementation rate is slow. Thus, this work looks at state-society relations in reaching SDGs 6.1. and 6.2. in Kazakhstan.

The survey asssessed available 176 water-related functions in the Government of Kazakhstan using the Integrated water resources  management tool-box. Additionaly, the questionnaire of about 1300 villagers was conducted in all the villages (which are 153 in total) of Atyrau region, Kazakhstan during September-November 2022, to assess the access to drinking water and sanitation services and the needs for improvement.

The findings show that in the “Policy” area the functions for adaptation to climate change are poorly expressed, especially climate resilient WASH systems; the role of customary law in the field of both the use of water resources and access to drinking water and sanitation is barely reflected in the legislation. In the "Organization" area there is a lack of functions in operation and monitoring of decentralized water supply and sanitation services; the organization of civil society is not formally expressed; training of water management specialists is not reflected as a responsibility.  In the field of using various tools of Integrated Water Resources Management, the weakest function of the government is communication with society and their reflection in public policy, in particular, the introduction of the concept of virtual water, water footprint, public awareness and education; economic instruments and effective demand management are little reflected in the functions of the state.

More than half of rural citizens use water from decentralized sources and mainly use pit latrines. The field survey has showed the high level of responsibility of the local villagers for decentralized sanitation and drinking water supply services, with high request to be educated on how to maintain those systems in a more sustainable way. It might be concluded that people do have relatively high rate of responsibility to maintain the water supply and sanitation systems. However, the policy and the govenmental functions do lack meeting these societal needs for education and, in a broder context, integrating people into water projects. "The science" or Reserchers could play an important role bridging State and Society to increase the feasibility of water and sanitation state-run programs. 

 

 

How to cite: Tussupova, K. and Zhupankhan, A.: Reaching SDGs 6.1 and 6.2 in Kazakhstan: State - society relations, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-12572, https://doi.org/10.5194/egusphere-egu23-12572, 2023.

EGU23-12680 | ECS | PICO | HS1.1.3

GEB: A large-scale agent-based socio-hydrological model – simulating 10 million individual farming households in a fully distributed hydrological model 

Jens de Bruijn, Mikhail Smilovic, Peter Burek, Luca Guillaumot, Yoshihide Wada, and Jeroen Aerts

Humans play a key role in the hydrological system, and their decisions influence the entire water system from tributary to river mouth. To fully comprehend how the human-natural water system evolves over space and time, and to investigate the systemic effects of climate change and human interventions, it is important to consider human behaviour and feedbacks to the hydrological system simultaneously at the local household- and large basin scales.

Therefore, we present GEB (Geographical, Environmental and Behavioural model); an agent-based model coupled to a fully distributed hydrological model that can simulate the behaviour and daily bi-directional interaction of more than 10 million individual farm households and reservoir operators with the hydrological system. Through this coupling, each individual farmer with unique characteristics and location can make daily decisions, such as irrigating their crops from surface-, reservoir-, or groundwater, planting and harvesting crops, investing in adaptation options (e.g., irrigation wells and sprinkler irrigation). All these decisions can be based on the available water in their environment, the status of their crops, their risk perception, crop price, water price, and weather conditions etc. Similarly, reservoir operators can regulate the availability of water for irrigation, and downstream releases of water based on the state of the hydrological system as well as communication with farmer agents.

GEB is dynamically linked with the spatially distributed hydrological model CWatM at 30’’ grid resolution (< 1km at the equator). Because many small-holder crop fields are much smaller, CWatM was specifically adapted to implement dynamically sized hydrological response units at field scale / sub-grid level, providing each agent with an independently operated hydrological environment.

While the model could be applied anywhere, we show an implementation with local and basin-wide feedbacks in the heavily managed Krishna basin in India, encompassing ~8% of India’s land area and ~12.1 million farmers. Here, we quantify bi-directional feedbacks such as the reservoir paradox and test various policies, such as providing subsidies for adaptation options (e.g., irrigation wells, sprinkler irrigation), and quantify effects on the hydrological system as well as downstream farmers.

In this implementation, GEB uses approximately 15 GB of RAM memory and can thus be used on an above average personal laptop. Computational requirements scale linearly with basin size, assuming similar farm-size distribution.

How to cite: de Bruijn, J., Smilovic, M., Burek, P., Guillaumot, L., Wada, Y., and Aerts, J.: GEB: A large-scale agent-based socio-hydrological model – simulating 10 million individual farming households in a fully distributed hydrological model, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-12680, https://doi.org/10.5194/egusphere-egu23-12680, 2023.

EGU23-13384 | ECS | PICO | HS1.1.3

Monitoring flood risk evolution: A systematic review of flood risk evolution assessments 

Nele Rindsfüser, Andreas Paul Zischg, and Margreth Keiler

Flood risk is changing over time. Climate change, land-use change, human interventions and socio-economic developments have an influence on the evolution of flood risk. Thus, the future dynamics of drivers influencing hazard, exposure and vulnerability and consequently flood risk evolution is uncertain. Therefore, flood risk management is confronted with deep uncertainties and need to continuously adapt to future circumstances. New management strategies are required to ensure the safety level of humans and their assets and reduce losses from floods. Adaptive flood risk management is a way to cope with such uncertainties. However, the implementation of adaptive flood risk management requires a flood risk monitoring system that screens critical developments of hazard, exposure, or vulnerability and warns the user when a critical point in flood risk evolution is approached. In order to develop a conceptual framework for a flood risk monitoring system, we conducted a systematic review of flood risk evolution assessments. We analysed how flood risk is conceptualised, which factors are assessed to analyse evolutions in one or more risk component, which methods are used to assess flood risk evolution and which risk outcomes are identified. We discuss the main concepts of monitoring the spatiotemporal changes of the components of risks and how the changes of these components contribute to the evolution of risk. We furthermore discuss the data sources, issues of spatial and temporal scales, and how the components of risk coevolve.

How to cite: Rindsfüser, N., Zischg, A. P., and Keiler, M.: Monitoring flood risk evolution: A systematic review of flood risk evolution assessments, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-13384, https://doi.org/10.5194/egusphere-egu23-13384, 2023.

EGU23-14419 | ECS | PICO | HS1.1.3

Geopolitical risk induced by terrestrial moisture supply to agricultural hotspots 

Jose Andrés Posada-Marín, Juan Fernando Salazar, Lan Wang-Erlandsson, Maria Cristina Rulli, and Fernando Jaramillo

Water availability can be linked to a country's stability, internal security, and the occurrence of violence and governability, in the environmental change context. For instance, lack of access to water resources can trigger political conflicts, be used as a tool for political negotiation or attacks on water infrastructure can be used as a source of intimidation. The potential political risks associated with water availability take particular relevance at the scale of international and transboundary hydrological basins and under conditions of water-food scarcity or political instability. To date, although water risks occurring within the boundaries of the hydrological basin have been studied across several case studies in the literature, the issue of risks arising from water upwind-downwind dependency has been overlooked. For instance, precipitation in a hydrological basin or agricultural centre regions with a high dependency on terrestrial moisture recycling may originate in upwind terrestrial areas outside of the basin boundaries. Here we study geopolitical risk related to this water dependency by analizing terrestrial moisture recycling. Our analysis shows that some hydrological basins in Africa, Asia and South America present a high risk of experiencing geopolitical conflicts when there is a large extension of croplands, high moisture recycling dependency and their precipitationsheds extend over warmongering countries. Hence, our results indicate that addressing transboundary water security from a surface perspective can underlook potential geopolitical conflicts that may threaten regional water-food security and peace. These risks need special international attention to guarantee global peace and agricultural production.

How to cite: Posada-Marín, J. A., Salazar, J. F., Wang-Erlandsson, L., Rulli, M. C., and Jaramillo, F.: Geopolitical risk induced by terrestrial moisture supply to agricultural hotspots, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-14419, https://doi.org/10.5194/egusphere-egu23-14419, 2023.

EGU23-15219 | PICO | HS1.1.3

Assessment of change in drought risk influenced by water management 

Elena Ridolfi, Laura Soncin, Alessia Matano, Fabio Russo, Francesco Napolitano, Giuliano Di Baldassarre, and Anne Van Loon

Disaster risks are the results of complex spatiotemporal interactions between risk components, impacts and societal response. In the context of the water supply chain, human processes have altered hydrological processes through the construction of reservoirs to dispose of the water resources with higher predictability and productivity. While reservoirs may attenuate flood events and help to bridge through period of water scarcity, they may also aggravate drought events in terms of duration and severity. The long-term effect associated to the presence of reservoirs is an over-reliance on the water supply hypothesized as constant and abundant as provided by the hydraulic structure, which in turn increases the vulnerability and the economic damage in case of a drought event occurrence. In addition, socio-economic and political changes should not be underestimated, as the social, economic, and political context can influence the impact and response to extreme events. Indeed, it has been observed that during long periods of drought, variations in exposure and in vulnerability have occurred, due to social dynamics taking place as a result of the extreme event, e.g. the natural migration of the population to water sources.
Here we aim at understanding the changes in risk components and the resulting impacts of structural measures, such as reservoirs, and also of nature based solutions in relation to consecutive extreme events. Different case studies around the world are considered to untangle the complexity of the dynamic relationship between human and hydrological processes.

How to cite: Ridolfi, E., Soncin, L., Matano, A., Russo, F., Napolitano, F., Di Baldassarre, G., and Van Loon, A.: Assessment of change in drought risk influenced by water management, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-15219, https://doi.org/10.5194/egusphere-egu23-15219, 2023.

EGU23-15238 | ECS | PICO | HS1.1.3

Dynamic risk modelling of a coupled human-drought system under multi-drought conditions 

Maurice Kalthof, Jens De Bruijn, Hans De Moel, Heidi Kreibich, and Jeroen Aerts

Drought risk is modified through hazard, vulnerability and exposure, and exacerbated by management shortcomings. A quantitative understanding of the combined effects of these drivers is required to effectively lower risk. Yet, knowledge about the dynamics and effects of risk drivers over time and space and the human-natural feedbacks that steer them is largely lacking. In this study, we propose using GEB, the first large-scale coupled-agent based hydrological model that simulates all individual farmers at field scale, to systemically quantify the relations between dynamic hazard, vulnerability, exposure, management and drought risk over a multi-drought period in the Bhima basin, India. First, we parametrized the coupled hydrological model with meteorological and hydrological data to capture hydrological drought  conditions of different paired drought events. Next, we develop the agent based model part to simulate the drought management behavior of two million farmers and how they respond to drought events. To simulate this behavior, we applied the protection motivation theory, supplemented by theory of planned behavior, to describe farmer agent behavior. The parameters of these theories were parametrized with survey data of Indian farmers fitted to the statistical distribution of the two million Bhima basin farmers. To study the dynamic attribution of the three risk drivers, a Global Sensitivity Analysis of all factors was performed at consecutive time intervals, showing the interaction of drivers before and after each drought event, as well as between the two events. The results are expected to further the understanding of drought risk dynamics and what disaster risk reduction measures can optimally reduce impacts in the long term.

How to cite: Kalthof, M., De Bruijn, J., De Moel, H., Kreibich, H., and Aerts, J.: Dynamic risk modelling of a coupled human-drought system under multi-drought conditions, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-15238, https://doi.org/10.5194/egusphere-egu23-15238, 2023.

EGU23-16540 | PICO | HS1.1.3

Examining the contribution of human induced climate change on global drought characteristics 

Aristeidis Koutroulis, Manolis Grillakis, and Konstantinos Seiradakis

Drought is generally considered a slow process natural hazard. However, the faster onset and strength of recent events have received great attention. Climate change and human activities can both play a role in altering the characteristics of droughts, including their speed of development and intensity. Climate change can, for example, indirectly impact droughts by changing the amount and distribution of precipitation, while human activities, such as land management, can directly alter the water content of the soil. In this study, we run the JULES-W2 land surface model with the counterfactual stationary ISIMIP3a climate dataset, a hypothetical climate without climate change [1], and transient land use changes based on observations. We use soil moisture as a water deficit indicator and a framework for calculating the hydrological drought propagation speed [2] to define drought characteristics. We compare results against those calculated from historical runs with climate-related forcing based on observations (factual) to examine historical imposed long-term changes attributed to human-induced climate change. Our results show that climate change could significantly impact the speed of development and intensity of droughts. Some regions like Congo rainforest, Europe and the western US are simulated as hot spots of more fierce droughts, while others (e.g. East African mountains) may have faced milder droughts as a result of climate change. These changes can have important consequences for the productivity of agricultural lands, the health of ecosystems, and the availability of water for human use. Future climate change highlights the implications of faster droughts on risk management and challenges the research of drought hazard prediction.

 

 

[1] Mengel, M., et al. “ATTRICI v1.1 – counterfactual climate for impact attribution.” Geosci. Model Dev., 14, 5269–5284.

[2] WU, Jiefeng, et al. Hydrological drought instantaneous propagation speed based on the variable motion relationship of speed‐time process. Water Resources Research, 2018, 54.11: 9549-9565.

 

Acknowledgements: “Co-funded by the ERASMUS+ Programme of the European Union” (Contract number: 101004049 — EURECA-PRO — EAC-A02-2019 / EAC-A02-2019-1).

How to cite: Koutroulis, A., Grillakis, M., and Seiradakis, K.: Examining the contribution of human induced climate change on global drought characteristics, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-16540, https://doi.org/10.5194/egusphere-egu23-16540, 2023.

EGU23-16655 | PICO | HS1.1.3

Land subsidence and coastal retreat as observed using Sentinel-1, tide dynamics, and socio-cultural survey of Sayung, Demak, Indonesia 

Yus Budiyono, Qoriatu Zahro, Aulia Oktaviani, Bondan Fiqi Riyalda, and Rapti Siriwardane-de Zoysa

The coastal zone of northern Java experiences rapid land subsidence. Satellite-derived InSAR data and GPS had provided evidence  displaying the spatio-temporal rates of the subsidence. Interestingly, inhabitants do not always recognize this phenomenon. However, they do recognize that flooding from the sea (called ‘rob’) has changed from gift to disaster, viz. from shallow infrequent flooding that carry inshore fishes, to regular deep and widespread disastrous floods. In the Demak regency, more than 300 families have moved to locations further inland. In some locations rob flooding has caused a coastline retreat of up to 5kms.

Our initial Sentinel-2 analysis comparing 2016 and 2022 images have showed the change of ecosystem in the area. In addition to that, social surveys revealed timely change of the ecosystem and point places where coastlines have moved.

For this study, we use Sentinel-1 imagery for SAR coupled with tide data to determine the behavior of coastline change from 2018-2022. Sentinel-1 is selected due to the temporal resolution and performance in  all-weather. Ground Range Detected (GRD) of Sentinel-1, is single look complex data projected using an earth ellipsoid, will be used as main input in spatial analysis to observe shoreline condition. There are 4 types of polarization of GRD data: HH,VV, HH+HV and VV+HV. Polarization type will be tested and determined to get less noise images result. Image masking and pixel analysis will sequentially be conducted to segregate the land and the sea. The analysis will be managed in Sentinel Application Platform (SNAP).

Tide data plot from nearby station is used to assign at what phase Sentinel-1 imagery is acquired. Additional analysis from tide data plot is applied to predict land/inundation at important sites and when imagery is not available. 

The social research component of the study through preliminary survey data , our initial survey showed residents relocation had been started before the period covered by the SAR data sets. Hence, random purposive sampling will be used for a follow-up mixed-methods survey to gather more data on social and economic dynamics arising from the geomorphological shifts in coastline. 

Ultimately, we hope  our study will help unravel land subsidence and the resulting coastline retreat to provide a strong basis for mitigation and adaptation options by the people and the government.

How to cite: Budiyono, Y., Zahro, Q., Oktaviani, A., Riyalda, B. F., and Siriwardane-de Zoysa, R.: Land subsidence and coastal retreat as observed using Sentinel-1, tide dynamics, and socio-cultural survey of Sayung, Demak, Indonesia, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-16655, https://doi.org/10.5194/egusphere-egu23-16655, 2023.

EGU23-17019 | ECS | PICO | HS1.1.3

Drought intensity and successiveness together displace populations in Somalia 

Woi Sok Oh, Juan Rocha, and Simon Levin

In recent years, a great number of Somalis are involuntarily displaced within the country. However, we do not fully understand what and how climatic, environmental, and socio-political drivers push internally displaced persons (IDPs). Among several climatic drivers, what is statistically significant to internal displacement? Is the drought intensity alone a key driver of displacement? Are social network structures important in displacement decisions? To provide quantitative evidence, we developed a bootstrapping temporal exponential random graph model (bTERGM) for internal displacement decisions in Somalia. We used the Protection and Return Monitoring Network dataset with drought indices based on precipitation, temperature, and vegetation from the Somali Water and Land Information Management. We found that IDPs tend to consider both the intensity and successiveness of droughts based on precipitation, temperature, or vegetation. The Intensity of each component alone was not a significant driver for Somali IDPs. Local network structures were not very significant in the temporal model at the monthly scale, while previous displacement experience played a critical role in IDP movements. Our results help us better understand the displacement decision-making process so that policymakers can predict IDP movements and establish adequate policies.

How to cite: Oh, W. S., Rocha, J., and Levin, S.: Drought intensity and successiveness together displace populations in Somalia, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-17019, https://doi.org/10.5194/egusphere-egu23-17019, 2023.

EGU23-1853 | PICO | HS1.1.4

Tool to assess the effectiveness of restoring physical conditions in riparian wetlands 

Gabriela Ioana-Toroimac, Gabriela-Adina Moroșanu, Ionuț-Andrei Șandor, Cătălina Stoica, and Dana-Maria Constantin

The success of river restoration is a controversy subject depending on chosen reference conditions and stakeholder perspective. Therefore, the tool to assess the effectiveness of restoring physical conditions in riparian wetlands aims to be a comprehensible piece of evidence to policy-makers. The assessment is based on three hypotheses: (i) the restoration should have standard-based results; (ii) the restoration should respect principle-based results; (iii) the nature is more valuable without human pressures. Therefore, the multi-criteria methodology includes three categories of indicators: (i) to detect results compared to pre-restoration conditions as well as to historical conditions; (ii) to estimate the functionality of physical conditions compared to expert opinion; (iii) to analyze the naturalness of a river site. Each indicator is given a score compared to hypothetically successful effects of the restoration based on an earth scientist approach. The overall score allows to classify the effectiveness of river restoration on a five-class scale from very good to poor. The tool is validated for the Comana Marsh on a second order tributary of the Danube River in Romania. A small-size dam and a system of concrete dykes was built to recreate a marsh upstream, in the floodplain. According to the tool: (i) the effects (e.g., surface-water area, depth) were a success compared to pre-restoration conditions, yet they could not recreate the historical conditions; (ii) new processes (e.g., anastomosing river pattern) appear to be functional when compared to scientific expectations; (iii) the river site gained hybrid features (i.e., rewilding in the context of human pressures). The effectiveness of restoring the Comana Marsh was estimated as being good. The tool could be further developed by integrating other groups of indicators based on stakeholders’ perspective. Understanding the theoretical results of river restoration could help policy-makers to gain confidence and further finance this domain underdeveloped in Romania.    

This work was supported by a grant of the Ministry of Research, Innovation and Digitization, CNCS - UEFISCDI, project number PN-III-P1-1.1-TE-2021-0600, within PNCDI III.

How to cite: Ioana-Toroimac, G., Moroșanu, G.-A., Șandor, I.-A., Stoica, C., and Constantin, D.-M.: Tool to assess the effectiveness of restoring physical conditions in riparian wetlands, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-1853, https://doi.org/10.5194/egusphere-egu23-1853, 2023.

Climate change alters the water cycle, which makes adaptation in water management necessary. The interdisciplinarily coordinated transdisciplinary project KlimaRhön aimed at developing adaptation strategies in water management in the UNESCO biosphere reserve Rhön in Central Germany. Experts agree that scientific and stakeholders’ knowledge should be involved to develop adaptation strategies, which requires good integration tools.

To identify adaptation strategies in the participatory process of the project KlimaRhön, we integrated the knowledge of hydrologists, sociologists and stakeholders while embracing uncertainty with a Bayesian Belief Network. For this, sociologists introduced that the acceptance of relevant actors is needed to implement adaptation measures and hydrologists introduced a range of potential future changes in groundwater recharge. In the first workshops of the participatory process, the stakeholders jointly identified possible adaptation measures. In the last workshops, we focused on two adaptation measures, which are 1) the protection of springs taking into account pasture water supply and 2) the fusion of small water suppliers in a region, and planned to find strategies to stimulate their implementation. For this, the stakeholders identified the relevant actors whose acceptance to implement those adaptation measures is needed. Then, the stakeholders identified and weighted factors that influence the acceptance of the relevant actors to implement the respective adaptation measure. This knowledge was then integrated in two Bayesian Belief Networks (for two adaptation measures) and a suitable communication of the Bayesian Belief Networks, which also focused on the communication of the embraced uncertainty, was developed. In the last workshop in the participatory process, the Bayesian Belief Networks were presented to the stakeholders and discussed. In the presentation, the stakeholders could explore which combinations of factors can enhance the acceptance of the relevant actors for the adaptation measure and thus the probability that they implement it for different degrees of climate change impacts.

The conditional probability tables for the Bayesian Networks were derived directly from the stakeholder weightings. Thus, stakeholders did not need to fill out conditional probability tables, which would have been difficult for most of them, and time-consuming. Bayesian Belief Networks show the uncertainty of possible future conditions through the many possible combinations of factors, which might have enhanced the understanding of stakeholders for the need of flexible adaptation strategies. The stakeholders appreciated the good overview of the many interdependencies and their influence on the acceptance of the relevant actors to implement the adaptation measure. In this contribution, we present our integration approach, the Bayesian Belief Networks, its communication as well as its evaluation by the stakeholders. 

How to cite: Müller, L. and Döll, P.: Transdisciplinary knowledge integration and embracing of uncertainty with Bayesian Belief Networks in water management, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-2094, https://doi.org/10.5194/egusphere-egu23-2094, 2023.

EGU23-4485 | PICO | HS1.1.4 | Highlight

Translating hydrology research into practice: A Canadian Perspective 

Alain Pietroniro, Prabin Rokaya, Corinne Schuster-Wallace, and John W Pomeroy

Hydrology research is regarded as vital for advancing human development and environmental conservation through improved hydrological process understanding and by devising solutions to address water management challenges. This is particularly acute in a time of global change and the need to find pathways to water sustainability.  Success for research in hydrology is often measured through quantitative research outputs, such as the number of journal publications, citation indices, number of students trained, patents, and external research funding. User involvement in the research and development process is rarely considered a metric for success in hydrology. Despite successful scientific or engineering advancements, a greater scientific understanding of hydrology and ever-increasing publications, much of the research has limited uptake by practitioners and implementation into practice, leading to a growing gap between research and practice.  This lack of utilisation is not due to a lack of need by users, but rather is a symptom of the disconnect between these advances and research that would most add value to practitioners and their application needs. We explore some outstanding challenges in translating academic research into practice and make some recommendations to bridge the increasing gaps between research and practice through a transdisciplinary approach, user engagement metrics in funded research and strong knowledge mobilization. We also discuss the success and challenges of these approaches in the Global Water Futures program along with lessons learned.  

How to cite: Pietroniro, A., Rokaya, P., Schuster-Wallace, C., and Pomeroy, J. W.: Translating hydrology research into practice: A Canadian Perspective, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-4485, https://doi.org/10.5194/egusphere-egu23-4485, 2023.

As the longest river in Asia, the Yangtze River has shown its impact on human societies with floods recorded since 12th century. In 1931, the Yangtze River has manifested its force again with one of the deadliest floods ever recorded in Chinese history, causing 422,499 deaths, damages to more than 25.2 million people and 58.7 billion m2 farmland. Similar flood occurred again in 1954, resulting in 31,762 deaths, damages to 18.9 million people and 31.7 billion m2 farmland. Researches have shown that 1954 flood being larger and higher compared to 1931 flood. However, it is still unclear for what reason that a more severe flood leading to less damage. Was it because of the change of policy and what can we learn from it? To answer this question, first, we constructed a conceptual framework of 1930s and 1950s agricultural society. Then, the flood inundation process of 1931 and 1954 floods was reconstructed with gauged rainfall dataset. After referring to the investigation report, the inundation information was applied to re-estimate the flood damage on farmland, houses, and residents under different scenarios. Furthermore, apart from traditional countermeasures, the effect of society transformation with floods were estimated using the potential crop production (PCP). Finally, an agent-based model (Farmer Landlord Inundation Production, FLIP) was constructed to simulate the agricultural transformation and its impact on residents’ response. The results have shown that traditional countermeasures were of certain effect. For example, the reinforcement of levees in 1950s was more effective in reducing inundation area of 8% compared to 1931, while the construction of detention basins accounted for 2%. However, with only traditional countermeasures failed to explain the relative success of agricultural product in 1954. Which, according to PCP result, the observed rice production was 12% higher than potential in 1954, while it was 29% lower in 1931. Here we assumed such difference could be ascribed to drastic society transformation in 1930s and 1950s (e.g., increase of absentee landlords in 1930s, land reform movement in 1950s). The effect of which was partially demonstrated with FLIP model, indicating an increase of crop production after eliminating landlords during floods. Our results demonstrate how society transformation are likely to affect the damage of and response to floods in a different (sometimes more important) way from traditional countermeasures in modern Chinese history. We anticipate our research to be a starting point towards deeper understanding of human and hazard, and the knowledge of which is likely to be applicable to many other regions and times.

How to cite: Liu, C., Kawasaki, A., and Shiroyama, T.: Flood protection in a changing society: a perspective from historical agriculture transformation during 1931 and 1954 floods in Yangtze River Basin, China, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-6794, https://doi.org/10.5194/egusphere-egu23-6794, 2023.

EGU23-8725 | PICO | HS1.1.4

RadClim BSR - Towards a Radar-based Precipitation Climatology for the Baltic Sea Region 

Blaine Lowry, Andreas Hoy, and Hossein Hashemi

Project Background: The RadClim BSR project aims to establish the feasibility of developing a radar-based precipitation climatology in the Baltic Sea Region (BSR). The project involves partners in countries across the BSR including Sweden, Estonia and Poland. The status of radar data archiving, utility of the data, and any data harmonisation requirements across the partner countries and the BSR in general are being investigated. Partners in Sweden, Estonia and Poland are acting as country coordinators, reaching out to a large range of actors to thoroughly explore their needs pertaining to radar climatology, utilising a user needs survey (ongoing from early February-March 2023). Consultations with the national weather services in Germany and Finland, who have already undertaken steps in radar climatology development, are aiding in ensuring best practices are adhered to. This seed project has the intention of laying the framework for the full development of a radar-based precipitation climatology (datasets and visualisations) spanning the BSR, relevant for a large range of actors in the near future.

EGU poster: At EGU 2023, we will present the results of the user needs survey that was distributed to a wide range of relevant actors in the project partner countries of Sweden, Estonia and Poland. The surveys were translated into each countries official language before being distributed, to maximise participation and ensure all representatives who should offer their perspective could, regardless of English language capacity. Through to the end of the project in early 2024, the results from this survey will be analysed and summarised, to form the user needs assessment for a radar-based precipitation climatology across the BSR.

How to cite: Lowry, B., Hoy, A., and Hashemi, H.: RadClim BSR - Towards a Radar-based Precipitation Climatology for the Baltic Sea Region, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-8725, https://doi.org/10.5194/egusphere-egu23-8725, 2023.

EGU23-11221 | PICO | HS1.1.4

Progress and perspectives in hydrological modelling and forecasting across scales 

Antara Dasgupta and the Joint Virtual Workshop ECMWF-CEMS-C3S-HEPEX-GFP Team

The last decades have seen unprecedented progress in ensemble hydro-meteorological modelling and forecasting on a range of temporal and spatial scales. Such progress also raises new challenges, especially with regards to connecting hydrology from global to local scales, as well as hydrological sciences research to operations. To discuss these challenges, the Joint Virtual Workshop "Connecting global to local hydrological modelling and forecasting: challenges and scientific advances” (29 June - 1 July 2021) was recently organized [*]. It brought together over one thousand people from around the world, including scientists, disaster managers and stakeholders operating at the local, national, continental and global scales. In this study, we summarise the state-of-the-art presented and discussed at the workshop. In particular, we provide an early career perspective on the insights and experiences shared during the workshop, highlighting recent advances and ongoing challenges in hydrological modelling and forecasting, as well as on the use of forecasts for decision-making from global to local scales. From the many topics covered during the workshop, which included hydrological model development (including Earth System modelling, machine learning applications and hybrid dynamic-statistical forecasting), skill assessment, uncertainty communication, forecasts for early action, co-production of services and incorporation of local knowledge, Earth Observations, and data assimilation, we focus on the contributions to science and operations from the hydrological forecasting community. Our analysis highlights the critical need to better connect hydrological services and impact models to societal needs and local decision-making through effective communication, capacity building and co-production. The core work of creating new methods and products and the move towards Earth System modelling need to be balanced by multidisciplinary collaborations that effectively bring tools to practice. We expect that research tackling these challenges will increase further in the next decade.

[*] Workshop organizers: European Centre for Medium-Range Weather Forecasts (ECMWF), the Copernicus Emergency Management (CEMS) and Climate Change (C3S) Services, the Hydrological Ensemble Prediction EXperiment (HEPEX), and the Global Flood Partnership (GFP)

How to cite: Dasgupta, A. and the Joint Virtual Workshop ECMWF-CEMS-C3S-HEPEX-GFP Team: Progress and perspectives in hydrological modelling and forecasting across scales, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-11221, https://doi.org/10.5194/egusphere-egu23-11221, 2023.

EGU23-11305 | PICO | HS1.1.4

Decision-support system for water availability estimation 

Sašo Šantl, Maja Sevšek, and Katarina Zabret

The management of water resources, their allocation and use is mainly directed by the policy at the strategic scale. In that way, the different sector interests can be coordinated, as well as principles of sustainable water use and goals of environmental conservation can be ensured. However, even the decision making at the strategic scale (i.e. at the level of the entire country) requires reliable information that provides sufficient support for decision makers in planning the further use of water resources. Accordingly, at the initiative of the decision maker (Ministry of the Environment and Spatial Planning of the Republic of Slovenia) the researchers at the Institute for Water of the Republic of Slovenia have developed a decision support system for water availability estimation in Slovenia. A multi-criteria approach was used, combining scientific approach in estimating the available water amounts (discharge in ungauged locations) and coordinated approach in setting the criteria, indicating the vulnerability of the environment according to specific locations and the attractiveness of that locations in terms of water use. The scientific aspect was used for the establishment of the methodology for the estimation of discharge in ungauged locations. Different machine learning and data mining techniques were tested, however Top kriging (Skøien et al., 2006) method was selected as the most accurate for assessment of the discharge across the country’s catchments, larger than 10 km2. Estimated characteristic discharges were then revised according to the environmental needs to evaluate the amounts of water available for further use. However, the selection of the criteria was performed through interdisciplinary collaboration with experts and decision makers from various fields. During settling of the selected criteria, the importance of cooperation was shown. Our initial list of the criteria was not sufficient, as some of the aspects were addressed differently or overlooked. It should also be taken into account that representatives of different fields determined the different importance of the included criteria.

Acknowledgement: The development of the decision-support system was financed by the Ministry of the Environment and Spatial Planning of the Republic of Slovenia through the Institute’s annual work programme for years 2020 – 2023.

How to cite: Šantl, S., Sevšek, M., and Zabret, K.: Decision-support system for water availability estimation, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-11305, https://doi.org/10.5194/egusphere-egu23-11305, 2023.

EGU23-11755 | PICO | HS1.1.4 | Highlight

OUTLAST - Development of an operational, multi-sectoral global drought hazard forecasting system 

Stefan Siebert, Neda Abbasi, Johannes Cullmann, Petra Döll, Tina Trautmann, Harald Köthe, Harald Kunstmann, and Jan Weber

Climate change and drought have imposed tremendous pressure on water resources in most parts of the world. Therefore, addressing drought impacts on water resources and socioeconomic conditions has gained attention to develop mitigation and adaptation strategies. Many innovative and cutting-edge modeling systems set up by academic institutions are exclusively available to academics and are not accessible or used by practitioners or policymakers. These constraints are in particular relevant in data poor regions where decision making and drought management are hampered by a lack of drought information. Therefore, within OUTLAST project (Development of an Operational, mUlTi-sectoral globaL drought hAzard forecasting SysTem), we aim to develop and implement the first worldwide, multi-sectoral, and operational drought forecasting system for quantifying drought hazard in water supply, riverine and non-agricultural land ecosystems, rainfed and irrigated agriculture. The forecasts provided by OUTLAST can also support better drought management and therefore contribute to the achievement of several Sustainable Development Goals (SDGs) of the United Nations, particularly SDG1(no poverty), SDG2 (zero hunger), SDG6 (clean water and sanitation), SDG13 (climate action) and SDG15 (life on land). In cooperation with pilot users in the project regions of Lake Victoria (Burundi, Kenya, Rwanda, Tanzania, and Uganda) and West and Central Asia (e.g. Afghanistan, Armenia, Azerbaijan, Iran, Iraq, Lebanon, Oman, Syria, Tajikistan, Turkey, Uzbekistan), the value of global-scale forecasts released for the subsequent six months for data-poor and transboundary basins will be tested. Through co-design, relevant drought indicators will be defined and the web portal and pilot applications of these global forecasts for drought management and water governance will be developed. We also systematically investigate the predictive ability of global-scale drought forecasts based on bias-corrected seasonal ensemble weather forecasts, as well as the factors influencing the predictive skill in terms of (i) the type of drought (soil moisture and hydrological droughts) and the affected sector, (ii) the length of the forecast period, (iii) seasonal and regional differences in predictive quality. Two global-scale models (WaterGAP and GCWM) will be further developed to provide operational and monthly drought forecasts globally at 0.5-degree spatial resolution and for a six-month forecast period. The applicability of the data and models for drought forecasting will be rigorously examined for different locations, sectors, and periods using historical reanalysis data and historical ensemble forecasts. This will entail using historical meteorological "forecasts" to generate drought forecasts for historical drought events reported for these regions and validating them regionally. Finally, an automated operational modeling system will be created to download and process the necessary meteorological input data, calculate the drought indicators, visualize them appropriately, and transfer them to the Global Hydrological Status and Outlook System (HydroSOS) at World Meteorological Organization (WMO). Through a flexible implementation (cloud-based), we will enable a potential transfer of the forecast system to different users. The use of the HydroSOS-portal of WMO to visualize project results and as an outlet of the drought forecast products will make optimal use of synergies and ensure high visibility and impact of the research performed in OUTLAST.

How to cite: Siebert, S., Abbasi, N., Cullmann, J., Döll, P., Trautmann, T., Köthe, H., Kunstmann, H., and Weber, J.: OUTLAST - Development of an operational, multi-sectoral global drought hazard forecasting system, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-11755, https://doi.org/10.5194/egusphere-egu23-11755, 2023.

EGU23-11975 | PICO | HS1.1.4 | Highlight

Open Methods in Operational Flood Hydrology – Considerations for researchers and practitioners 

Christopher Skinner and Duncan Faulkner

The merits of open science for hydrology are firmly established, widely embedded into research culture, and increasingly adopted within operational agencies. In the UK, it is common practice now for data collected by, and/or funded by, public bodies to be made available openly, licensed for both commercial and non-commercial use, and accessible via data portals and APIs. However, these same standards are not routinely applied to the methods and models used to evaluate flood risk.

This work, part of the UK’s community-led 25-year Flood Hydrology Roadmap, considered the potential role of open methods within UK operational practice. A review of the relevant literature was used to establish a definition and framework for open methods, which was refined based on consultation with practitioners. The framework was used to assess the current levels of ‘openness’ across UK practice, placing this in the context of challenges including governance, funding, and development histories. The study also considered international case studies of where open methods have been successfully implemented for hydrology and in other fields.

The review was used to develop an aspirational vision for the future operational use of open methods in UK flood hydrology, identifying key barriers and recommendations to manage and overcome them. Working with artists, creative provocations have been created to further the conversation, both within hydrology and along the subsequent links in the flood risk modelling chain. The review recommendations will be summarised as considerations relevant to both researchers and practitioners.

How to cite: Skinner, C. and Faulkner, D.: Open Methods in Operational Flood Hydrology – Considerations for researchers and practitioners, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-11975, https://doi.org/10.5194/egusphere-egu23-11975, 2023.

EGU23-11980 | PICO | HS1.1.4

Pro-active flood risk managment using a transdisciplinary multi-method-approach 

Mariele Evers, Adrian Almoradie, Joshua Ntajal, Britta Höllermann, Georg Johann, Helene Meyer, Annika Schüttrumpf, Sylvia Kruse, Fafali Ziga-Abortta, Daniel Bachmann, Roman Schotten, Mawuli Lumor, Charlotte Norman, and Kwaku Adjei

Water related extreme events are causing most of the disasters worldwide. Between 2001 and 2018 around 74% disasters were water-related and during the past 20 years, the total number of deaths caused only by floods and droughts exceeded 166,000, while floods and droughts affected over three billion people, and caused total economic damage of almost US$700 billion (EM-DAT, 2019). The number of events with water related extremes are expected to increase due to climatic and land use changes.

Thus, it is of utmost importance to identify ways to reduce water related risks. Potential hazards, exposure and vulnerability have to be identified, published and communicated. This is done for example in the European Union in a coordinated way, based on the European Flood Risk Management Directive. However, identifying risk only is not leading to actual actions and is not  sufficient to reduce risks. This became again obvious in 2021 when extreme floods caused more than 180 deaths in Germany and caused around 46 billion Euro damage. This and other events are revealing the need for closing the gap between theory and practise to establish proactive and preventive strategies and implementation of measures.

Ghana is one of the countries most prone to floods in West Africa. Its annual occurrence often leads to disasters that are mostly felt by the urban poor. Despite the existence of salient activities conducted in order to reduce the flood risk in Ghana, there are still persisting challenges (Almoradie et al. 2020).

In order to overcome the implementation gap from science to practice a participatory and transdisciplinary mixed-method approach for Ghana is pursuied. Transdisciplinary research integrates knowledge from various scientific disciplines and non-academic actors.In this way, results can be developed for challenges that are of use to society and science.In the long term, transdisciplinary research strengthens knowledge about the human-water/flood system, the desired state of this system and the way to achieve this state by transformative adaptation.

A participatory mixed-method approach comprising hydrological and hydrodynamic modelling, participatory mapping, questionnaires, workshops, focus group discussion, system dynamic modelling and the analysis of vulnerability including failure of critical infrastrcuture were employed (Evers et al. 2021) for three case study areas in Ghana. The dynamics of human-flood-interaction are identified together with practioneers and adaptation measures were identified in a participatory way. By this approach we are aiming to make our research actionable and to design and implement knowledge translation mechanisms.

 

Almoradie, A.*, de Brito, M.M.*Evers, M., Bossa, A., Lumor, M., Norman, C., Yacouba, Y., Hounkpe, J. (2020) Current flood risk management practices in Ghana: gaps and opportunities for improving resilience. International Journal of Flood Risk Management, doi:10.1111/jfr3.12664.

Evers, M., Almoradie, A., de Brito, M. M., Höllermann, B., Ntajal, J., Lumor, M., Bossa, A., Norman, C., Yira Yacouba, Y. Y.,J. H. Jean Hounkpe (2021): Flood risk management in Ghana: gaps, opportunities, and socio-technical tools for improving resilience, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-12683, doi:/10.5194/egusphere-egu21-12683

 

How to cite: Evers, M., Almoradie, A., Ntajal, J., Höllermann, B., Johann, G., Meyer, H., Schüttrumpf, A., Kruse, S., Ziga-Abortta, F., Bachmann, D., Schotten, R., Lumor, M., Norman, C., and Adjei, K.: Pro-active flood risk managment using a transdisciplinary multi-method-approach, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-11980, https://doi.org/10.5194/egusphere-egu23-11980, 2023.

Most existing climate impact assessments in Nepal only consider a limited number of generic climate indices such as means. Few studies have explored climate extremes and their sectoral implications, which in turn are key for informing policy and practice. This study evaluates future scenarios of extreme climate indices from the list of the Expert Team on Sector-specific Climate Indices (ET-SCI) and their sectoral implications in the Karnali Basin in western Nepal. First, future projections of 26 climate indices relevant to six climate-sensitive sectors in Karnali are made for the near (2021–2045), mid (2046–2070), and far (2071–2095) future for low- and high-emission scenarios (RCP4.5 and RCP8.5, respectively) using bias-corrected ensembles of 19 regional climate models from the COordinated Regional Downscaling EXperiment for South Asia (CORDEX-SA). Second, a qualitative analysis based on expert interviews and a literature review on the impact of the projected climate extremes on the climate-sensitive sectors is undertaken. We also used widely available global data sets such as DesInventar and national census data and disaster-specific mixed-effects regression models to assess the impact of precipitation extremes on landslide and flood mortality.  Both the temperature and precipitation patterns are projected to deviate significantly from the historical reference already from the near future with increased occurrences of extreme events. Results show winter in the highlands is expected to become warmer and dryer. The hot and wet tropical summer in the lowlands will become hotter with longer warm spells and fewer cold days. Low-intensity precipitation events will decline, but the magnitude and frequency of extreme precipitation events will increase. Furthermore, an increase in one standardized unit in maximum one-day precipitation increases flood mortality by 33%, and heavy rain days increase landslide mortality by 45%.

How to cite: Bharati, L. and Chapagain, D.: Policy and practice relevant climate change impact assessments: Case study, Western Nepal, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-13241, https://doi.org/10.5194/egusphere-egu23-13241, 2023.

EGU23-13956 | PICO | HS1.1.4

Optimisation of the water and climate science, policy and practice nexus: Insights from the AfriAlliance knowledge brokerage events. 

Jean-Marie Kileshye Onema, Uta wehn, Mamohloding Tlhagale, Seyram Sossou, and Tarryn Quayle

Over a five year period, a systemic approach to water and climate solutions refer to as social innovation was developed in the framework of the AfriAlliance project. The approach recognised the need to combine five aspects for increased relevance and synergies for the water and climate science, policy and practices. The above mentioned aspects included technological solutions, governance structures, capacity development, a business roadmap and knowledge brokerage events. This manuscript documents lessons learned from the fifteen knowledge brokerage events held across the African Continent.  These events provided a platform to 1060 participants who came across 125 innovations. Policy makers, funders, utility operators, scientists, non-governmental organisations, river’s authorities and organisations, entrepreneurs and practioners were represented. The AfriAlliance knowledge brokerage events covered all the 5 African sub-regions. These events were designed and implemented in an innovative way providing participants ample opportunity to network and engage with innovators after their pitch presentations. Specialised and high-level panels provided policy makers, funders and international cooperating partners an opportunity to share their perspectives with innovators and the audience. Policy makers recurrently indicated the need to align water and climate innovations and solutions to existing priorities and frameworks. Funders and international cooperating partners highlighted the limited capacity from innovators in terms of scalability and access to funding. These events also brought up the difficulty of always getting the right audience especially when the knowledge brokerage event took place in the framework of specialized conferences. The Covid-19 pandemic introduced also an additional layer of complexity and required some adaptation to the face to face set-up that was initially designed. Hence two out of the fifteen events took place online. The virtual setup appeared to reach a broader geographical audience but the interactions were not as effective as those organised in person.  These events have shown a considerable potential to bring together scientists, policy makers and practioners in order to match topical solution providers and the users. On the other hand, these kind of knowledge brokerage events remain project dependent and adhoc in nature for one to expect some long-term impact.

How to cite: Kileshye Onema, J.-M., wehn, U., Tlhagale, M., Sossou, S., and Quayle, T.: Optimisation of the water and climate science, policy and practice nexus: Insights from the AfriAlliance knowledge brokerage events., EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-13956, https://doi.org/10.5194/egusphere-egu23-13956, 2023.

EGU23-16702 | PICO | HS1.1.4

Advancing community water resources modeling in the Cooperative Institute for Research to Operations in Hydrology (CIROH) 

Steve Burian, Martyn Clark, Chaopeng Shen, Ray Spiteri, James Halgren, Arpita Patel, Ashley van Beusekom, Sagy Cohen, and Fred Ogden

The Cooperative Institute for Research to Operations in Hydrology (CIROH) is a consortium of 28 institutions to advance the National Oceanic and Atmospheric Administration’s (NOAA) science and services capabilities to provide actionable water resources intelligence. CIROH’s research aims to improve water prediction and supports four broad themes: (1) water resources prediction capabilities; (2) community water resources modeling; (3) hydroinformatics; and (4) application of social, economic and behavioral science to water resources prediction. CIROH outcomes will inform hydrological process understanding, operational forecasting techniques and workflows, community engagement in water modeling, open-source software development, translation of forecasts to actionable products, and use of predictions in decision making.

 

This presentation will focus on CIROH’s research in community water modelling. In this theme, CIROH research focuses on advancing the predictive capabilities of the next-generation National Water Resources Modeling framework (NextGen framework) that is being developed for operational large-domain water prediction at NOAA’s National Water Center (NWC). The presentation will give examples of ongoing CIROH model development efforts to (1) integrate physical process representations into the NextGen framework across multiple levels of process granularity; (2) assess accuracy-efficiency trade-offs in the numerical solution of model equations across large spatial domains; (3) coupling process components that have hitherto been neglected in large-domain terrestrial system models (e.g., glacier hydrology, snow redistribution, connectivity of wetlands, land-atmosphere interactions over sparse forests, tile drainage, etc.); and (4) use hybrid machine learning methods to advance large-domain parameter estimation capabilities. The presentation will also highlight the establishment of research enabling infrastructure to support CIROH’s ongoing modeling advancement efforts. In summary, we will identify major challenges encountered and the high-priority research that is needed to advance capabilities in large-domain hydrologic prediction.

How to cite: Burian, S., Clark, M., Shen, C., Spiteri, R., Halgren, J., Patel, A., van Beusekom, A., Cohen, S., and Ogden, F.: Advancing community water resources modeling in the Cooperative Institute for Research to Operations in Hydrology (CIROH), EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-16702, https://doi.org/10.5194/egusphere-egu23-16702, 2023.

EGU23-17248 | PICO | HS1.1.4

Enhancing the science-policy-practice nexus for effective and sustainable wetland Management in Southern Africa 

Dzikamayi Tanaka Nyatoro, Jean-Marie Kileshye Onema, Budzanani Tacheba, and Jane Olwoch

Effective natural resources management, especially of wetlands, are vital for the sustainability of livelihoods. This is further buttressed in Southern Africa where competing uses and users are increasingly putting pressure on these finite resources. The Southern African Science Service Centre for Climate Change and Adaptive Land Management (SASSCAL) with financial support from the African Union and the European Commission in the framework of the GMES programme endeavoured to develop a geoportal tool for effective wetland Management through a project called Wetland Monitoring and Assessment Service for Transboundary Basins in Southern Africa (WeMAST). WeMAST has an emphasis on capacity building and awareness raising for wetland assessment and monitoring in the following four transboundary river basins (Cuvelai, Okavango, Limpopo and Zambezi) across the SADC region. The WeMAST geoportal, developed during phase one, provides hydro-meteorological and physiographic attributes assessment and monitoring of wetlands. These include the spatial and temporal extent and status of wetlands, land cover and uses dynamics, flooding, vulnerability and fire indices. For the second phase, WeMAST puts emphasis on developmental impact on the ground hence some deliberate efforts are in place in order to enhance synergies between the scientists behind the concepts, the users, private sector and local communities on the ground as well as policy makers with the overall responsibilities of guiding the implementations of developmental pathways. In Phase II, policy and decision makers in the target countries (Angola, Botswana, Namibia, South Africa, Zambia and Zimbabwe) need to support upscaling and operationalization of the WeMAST geoportal.  As a result, the project consortium has now been designed in order to foster more interactions between stakeholders involved in wetland management through knowledge brokerage events where the geoportal tool, its products and services are disseminated, tested and validated to a great extent. Similarly an interface with policy makers has been established within the consortium through WaterNet via the Water Resources Technical Committee (WRTC) in order to appraise and involve SADC ministers in charge of water and natural resources management twice annually. The innovative and well-crafted approach of the WeMAST project under GMES offers a considerable room for enhanced synergies between policy makers, Scientists, the private sector and practioners for sustainable and effective wetland Management in the SADC region.

How to cite: Nyatoro, D. T., Onema, J.-M. K., Tacheba, B., and Olwoch, J.: Enhancing the science-policy-practice nexus for effective and sustainable wetland Management in Southern Africa, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-17248, https://doi.org/10.5194/egusphere-egu23-17248, 2023.

Recent developments in hydrologic science include a strong focus on open-source data sets and modeling tools. These developments can easily be leveraged into hydrologic education in the form of classroom exercises and term projects. Here we present a computational exercise designed to teach the concept of model structure uncertainty to students, using a specific selection of two catchments and two simple conceptual models from open-source data and tools.

The exercise first familiarizes the students with the modeling tool they will use and then has them calibrate and evaluate model performance on each combination of model and catchment. For these specific catchment and models, model structure uncertainty is the dominant source of uncertainty (compared to data, parameter and objective function uncertainties). The exercise includes guiding questions that help the students reach the defined learning goals. Trials at the Technische Universität Dresden show that the exercises are effective in doing so. This introduction to open-source models and data yields the benefit of being easily expanded on during further exercises and term projects.

How to cite: Knoben, W. and Spieler, D.: An example of using open-source data and hydrology models for classroom exercises and term projects, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-2675, https://doi.org/10.5194/egusphere-egu23-2675, 2023.

EGU23-2741 | Posters virtual | EOS2.4

Introducing the use of Open Data into the secondary education: A study on inland water quality 

Chrysanthi Tziortzioti, Elias Dimitriou, and Irene Mavrommati

Public and private organizations and institutions distribute a large volume of Open Data on a continuous basis with aim of increasing efficiency, saving time or reducing costs. Technological advancement offers easy access to open datasets that have potentially added value as educational resources in teaching and learning processes. Open Data provides the educational community with learning experiences related to real world problems and allows students to engage with activities normally undertaken by professionals, without increasing the level of difficulty. In this study, we designed an educational intervention that uses open data from the Institute of Marine Biological Resources and Inland Waters, and we investigated how it can be integrated into the Greek secondary school curriculum. The results suggest that this open data-based practice has increased students’ motivation and has had an impact on selfbeliefs on topics of aquatic environments as well as an impact on students’ perception of the importance of aquatic environmental problems in rivers and lakes. 

How to cite: Tziortzioti, C., Dimitriou, E., and Mavrommati, I.: Introducing the use of Open Data into the secondary education: A study on inland water quality, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-2741, https://doi.org/10.5194/egusphere-egu23-2741, 2023.

EGU23-5020 | ECS | Posters on site | EOS2.4

Design and construction of a rainfall simulator: an interdisciplinary student project towards sustainable development goals achievement 

Mateja Klun, Klaudija Lebar, Katarina Zabret, and Andrej Zdešar

Precipitation is one of the essential parts of the hydrological cycle. Regardless of the important role that precipitation plays for life on Earth, in extreme conditions, such as high intensities and amounts, it can negatively affect various ecosystem services (e.g., flood protection, agriculture). Precipitation is spatially highly variable. Traditionally, precipitation, with rain as the most common type, is measured over very small surface areas (of a few square decimetres) by rain gauges or sensors. However, reliable and representative rainfall data are crucial for understanding the interconnection of different parts of the hydrological cycle (e.g., rainfall interception by vegetation, rainfall erosivity) and quantification of flood, drought, water quality, and other water-related problems. Reducing the negative consequences of the mentioned problems is part of the 2030 Agenda sustainable development goals. Therefore, an interdisciplinary student project on the design and construction of a rainfall simulator was submitted to the University of Ljubljana's call for sustainable development student projects. Rainfall simulators are recognized as important tools for studying the effects of rain on soil. Rainfall simulators can be used in controlled conditions in the laboratory or with additional settings also in the field. The design and construction of the simulator is entirely within the domain of the project team of six students of environmental civil engineering and electrical engineering. This includes the choice of pipe materials, pump capacity, size and type of spray nozzles, development of a control system for monitoring and recording of results, and, last but not least, the determination of rain properties we would like to simulate (e.g., intensity). Three pedagogical mentors and one mentor outside the academia supervise the project. With such a project, group work and co-creation are encouraged among students, theoretical knowledge acquired within the curriculum is transferred into practice and knowledge is exchanged between different disciplines. Skills such as communication, critical thinking, organization of tasks and time management, interdisciplinary problem solving, analytical reasoning, information and technology literacy, are developed in the project. Additionally, such equipment will be used for teaching and research purposes in the future, which is another sustainable feature of this project.

How to cite: Klun, M., Lebar, K., Zabret, K., and Zdešar, A.: Design and construction of a rainfall simulator: an interdisciplinary student project towards sustainable development goals achievement, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-5020, https://doi.org/10.5194/egusphere-egu23-5020, 2023.

EGU23-8427 | Posters on site | EOS2.4

Web-apps as active learning tools in hydrology classrooms 

John Gannon

Active learning strategies such as simulations or problem sets have been shown again and again to be critically useful for helping students understand complex concepts. Students develop a more thorough understanding of processes or problem solving strategies when they are able to practice or explore them with hands-on activities. In hydrology, however, there are several concepts taught, even in introductory classes, where developing suitable activities for this type of learning is difficult. For example, even a simple water balance activity often requires a relatively thorough understanding of spreadsheets or a lot of tedious hand-calculations if students are going to explore relationships between multiple inputs and outputs. Similarly, even the most basic discussion of how a simple box model works is difficult to supplement with an activity that doesn’t involve spreadsheets or writing computer code. Furthermore, it is often beyond the scope of introductory level hydrology classes to teach programming or spreadsheet skills, and hand calculations often take a prohibitive amount of time. Web applications offer a tool to address some of these issues. With the development of tools like Shiny apps for R or Python, instructors with programming experience can relatively easily create interactive learning tools for their classes. Many studies in fields such as statistics and mathematics have shown that these web-apps aid in student learning. Furthermore, hosting and sharing these apps is becoming more accessible, with organizations like CUAHSI running shiny servers. In this presentation, I will show two examples of implementations of a web app to aid in student learning, one on the concept of a water balance, and one on running and parameterizing a basic catchment hydrology model. I will also discuss tools and strategies for building and hosting your own shiny app to address the learning goals for your classes.

How to cite: Gannon, J.: Web-apps as active learning tools in hydrology classrooms, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-8427, https://doi.org/10.5194/egusphere-egu23-8427, 2023.

EGU23-10592 | Posters on site | EOS2.4

Lessons from Adapting Applied Hydrology Instruction to Open Source Software Tools 

Daniel Kovacek and Steven Weijs

Resource use decisions in the extractive resource industry in Canada are supported in various ways by collection and analysis of water resources data.  Data quality assurance and analysis are influenced by the methods taught in academic training, the tools used to teach and practice, and industry standards and culture.  The growth in popularity of computer programming languages such as Matlab, Python, and R, and new web-based collaboration and publishing tools from Project Jupyter (Notebook, Book) have created opportunities for teaching applied hydrology in new ways that can support the evolving nature of data in hydrology practice, namely in treating open-ended problems more typical to industry practice.

The abrupt shift to web-based instruction at the undergraduate level in 2019 spurred development of interactive instructional content in an applied hydrology course at the University of British Columbia, in Vancouver, Canada.  Using the open-source Jupyter Book software framework, we developed open-access course material to complement the hydrology theory curriculum.  The new course content consists of a set of tutorials designed to give students a practical introduction to important components of engineering practice such as data quality assurance, and uncertainty in hydrological models.  The content is provided as an open-access online textbook with an embedded Python code interpreter.   With each successive cohort, the material has adapted to student feedback, namely in treating the types of open problems common in industry, and in the amount of programming experience required. 

How to cite: Kovacek, D. and Weijs, S.: Lessons from Adapting Applied Hydrology Instruction to Open Source Software Tools, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-10592, https://doi.org/10.5194/egusphere-egu23-10592, 2023.

EGU23-12489 | Posters on site | EOS2.4

The benefits of Open Science approaches when teaching hydrology 

Stan Schymanski

Open science is commonly associated with open access publications, and FAIR (findable, accessible, interoperable and reusable) data. Open source code is progressively being considered an essential component of open science, too. However, even if all these ingredients are available and openly accessible, it is often impossible to reproduce the graphs in a paper from the data and code provided. Which script was used on what part of the data to generate a given plot? Which version of a cited database was used, and what query to extract the presented data points? Moreover, even the basic steps of a scientific analysis, i.e. the derivation of mathematical equations, are often not traceable. Ever came across the famous “it follows that”, where, what follows, contains variables that were not present in the preceding equations?

Here I present part of a hydrology course based on a framework designed to address many of the above challenges. It is based on the open-source RENKU platform and deployed in a Jupyterhub instance at https://renkulab.io. RENKU enables the tracking of datasets and their versions, and records executions of code with their respective input and output files, producing a knowledge graph of the entire project and enabling the user to easily re-do all necessary steps to update relevant results whenever a data or code file is updated. RENKULAB uses the docker system to help reproduce the computational environment needed to re-execute the analysis. This greatly facilitates collaborative research and learning, as it removes the need for collaborators and students to recreate the computational environment in their local systems. Integration of GITLAB in RENKULAB facilitates student feedback and collaborative problem solving through issue tracking, where students can gain points by submitting meaningful issues and helping others.

The course also uses an open source package for mathematical derivations (ESSM, https://essm.readthedocs.org), which is based on the Python package Sympy, and facilitates clear definitions of variables including their dimensions and units, and dimensionally consistent fundamental equations. These can then be used to deduce derived equations by automatic solving of systems of equations for unknown variables, derivatives, integrations, and many other mathematical operations contained in Sympy. The package combines graphical depiction of equations, as seen in papers, with computational reproducibility of derivations and transparent re-use of equations in numerical code.

By employing Open Science approaches from the start, students become naturally accustomed to reproducible research and can use the skills they learn in any professional environments, as they are not bound to proprietary software that their future employers and collaborators may or may not have purchased licenses for.

How to cite: Schymanski, S.: The benefits of Open Science approaches when teaching hydrology, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-12489, https://doi.org/10.5194/egusphere-egu23-12489, 2023.

EGU23-12552 | Posters virtual | EOS2.4

The UK Hydrology Skills and Satisfaction Survey 

Christopher Skinner, Annie Ockelford, Andy King, Esther Goodship, and Helen Harfoot

The UK’s 25-year Flood Hydrology Roadmap was published in 2022. The Roadmap was developed by the UK hydrology community to identify the areas of greatest need and to deliver actions across four themes: Ways of Working, Data, Methods, and Scientific Understanding. Ways of Working Action W5 aims to build the ‘skills, esteem and value’ of flood hydrology but this is currently not possible as there is no baseline available. To provide a baseline, a UK-wide survey of hydrologists and the users of hydrology was conducted.

The survey was designed after consultation with hydrologists working in academia, consultancies, and other authoritative bodies in the UK. The objective of the survey was to baseline the current number, skills, satisfaction, backgrounds, and diversity of hydrologists practicing in the UK. A further consideration was to understand how prepared hydrology is as a discipline for anticipated changes in methods and skill requirements. The survey covered both low and high flow hydrology, not just flood hydrology.

In this presentation, we will summarise the key results of the survey and highlight the implications for hydrology training, education, and teaching. Finally, we will share our recommendations, from the perspective of operational users of hydrology, for the future skills needs in hydrology.

How to cite: Skinner, C., Ockelford, A., King, A., Goodship, E., and Harfoot, H.: The UK Hydrology Skills and Satisfaction Survey, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-12552, https://doi.org/10.5194/egusphere-egu23-12552, 2023.

EGU23-13006 | ECS | Posters on site | EOS2.4

Teaching by doing or a field course in our backyard: the first geosensing of the environment course in this geography institute 

Natalie Ceperley, Linus Fässler, Peter Leiser, and Bettina Schaefli

The ubiquitous "field trips in geography" type courses often exclude students on the basis of mobility and flexibility, have a high travel footprint, and rely primarily on passive knowledge.  In the summer of 2022, we taught a master level geography course, Geosensing of the Environment for the first time at the Geography Institute at the University of Bern. The course was team taught by the institute field technician, the assistant and master student, and a researcher in hydrology. This course is unlike anything currently or previously taught at our institute. It put the students in charge of their own scientific trajectories, taking them on a full scientific cycle "journey" from idea and question, to device development and measurement, to analysis and communication. The main goal of the course was for all students to use raspberry pi micro controllers or similar devices and a variety of sensors however they wish to build a scientific measuring device, while maintaining this course's relevance and connection to all physical geography subjects.

The pedagogical framework of the course was innovative in a number of ways, namely bringing together a self-learning module teaching the basics of programming microelectronic boards, a hands-on workshop where they got to build their own sensor device based on their own scientific questions, and a follow-up phase where they got to propose a bigger project using their progress in the workshop as a pilot. Students particularly appreciated the open-ended nature of the course that could be adapted to their interests. Although the students' backgrounds were not technical, by the end of the course, we had one group measuring CO2 over a freeway, one group analyzing temperature variation caused by balcony vegetation, and one group measuring water temperature profiles around Bern. In the end, one device was based on raspberry-pi pico and a second based on the sparkfun thing plus RP2040. In the future, we hope to put more emphasis on energy management and communication of sensor networks.  Improvements to this course must balance the goal to empower each student to "start from scratch" or to provide ready-to-go kits, leaving students to mainly choose which sensors they use.  Our main lessons learned concern teaching technical subjects in non-technical disciplines, focusing on instrumentation to transcend disciplines, transforming field courses to more accessible and lower-impact formats, and empowering students to build sensing devices starting with a blank sheet of paper (and a raspberry pi).

How to cite: Ceperley, N., Fässler, L., Leiser, P., and Schaefli, B.: Teaching by doing or a field course in our backyard: the first geosensing of the environment course in this geography institute, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-13006, https://doi.org/10.5194/egusphere-egu23-13006, 2023.

EGU23-13088 | Posters on site | EOS2.4

Making MacGyvers: lessons from a decade of maker education 

Rolf Hut, Miriam Coenders, and Gijs Vis

Regular visitors of the EGU General Assembly are familiar with the ‘MacGyver’ sessions where hydrologists present measuring solution they have designed, build and tinkered (often ducttaped) themselves. We often get asked how we convey the MacGyver mentality to our students: how to teach them the skills and attitude to tackle their own problems hands on?

We teach this in the undergraduate course ‘measuring water’. In this course the learning goals include teaching hydrology students how to measure the different states and fluxes in the water cycle. We approach this by having teams of students design, make and demonstrate their own sensor. This ‘maker-education’ approach is known for stimulating intrinsic motivation in students to work on their projects, but it also comes with its own challenges: how to make sure that all students learn about all different types of sensors and not only about the one they choose? How to steer students towards choosing a project topic that is both challenging enough and not too challenging, without giving them the idea you are curbing their freedom to choose their own topic?

In this presentation we will reflect on lessons learned from a decade of teaching ‘Measuring Water’ and provide take-aways applicable for all geoscientific teaching.

How to cite: Hut, R., Coenders, M., and Vis, G.: Making MacGyvers: lessons from a decade of maker education, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-13088, https://doi.org/10.5194/egusphere-egu23-13088, 2023.

EGU23-14794 | Posters on site | EOS2.4

Interactive understanding of groundwater hydrology and hydrogeology – the iNUX project 

Thomas Reimann, Roland Barthel, Steffen Birk, Daniel Fernandez-Garcia, and Zhao Chen

Groundwater represents more than 97% of the globally available freshwater resources. Groundwater is situated in geological structures in the subsurface and is therefore not visible, difficult to characterize, and manage. As a consequence, it is often not adequately considered by authorities, the general public – and in education. However, teaching and learning Hydrogeology and Groundwater Management at universities, but also as a part of continuing education training for professionals, is essential to deal with future challenges. For this reason, it is important to use suitable teaching material to improve the understanding of the complex topic of groundwater among these target groups. The recent challenge of the COVID-19 pandemic has increased the demand for digital and remote teaching. An ongoing Erasmus+ cooperation project named iNUX – interactive understanding of groundwater hydrogeology aims to address the need for digital teaching material. The project aims to achieve an interactive and digital learning environment in hydrogeology and groundwater management with a European but also global target of teachers and students.

Existing experience in teaching relevant groundwater subjects from highly reputable European universities will be used to develop interactive and digital teaching material focusing on basic and applied hydrogeology. The teaching material will cover basic theory in combination with field and laboratory applications in different European environments (Northern Europe, Central Europe, and the Mediterranean). The teaching material will comprise (1) various types of videos (e.g., field experiments, lab experiments, screencasts of calculations and software use), (2) interactive Jupyter notebooks that combine explanation with live code (e.g., based on Python), (3) various types of questions and problems that allow different assessments to enhance self-controlled learning of students. All materials are intended as open source and publicly available. The iNUX activities also comprise initiatives to establish interest groups to combine efforts towards larger pools of commonly developed digital teaching material (e.g., question pools) and to link with other activities like the 'Groundwater project' (https://gw-project.org/).

How to cite: Reimann, T., Barthel, R., Birk, S., Fernandez-Garcia, D., and Chen, Z.: Interactive understanding of groundwater hydrology and hydrogeology – the iNUX project, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-14794, https://doi.org/10.5194/egusphere-egu23-14794, 2023.

HS1.2 – Innovative sensors and monitoring in hydrology

EGU23-515 | ECS | Posters on site | HS1.2.1

Estimating sheet flow velocities using quinine as a fluorescent tracer in low luminosity conditions: laboratory and field experiments 

Soheil Zehsaz, João L. M. P. de Lima, M. Isabel P. de Lima, Jorge M. G. P. Isidoro, and Ricardo Martins

This study presents a technique based on the use of quinine as a fluorescent tracer, to estimate sheet flow velocities over various surface coverings (e.g., bare; mulched; vegetated; paved) in low luminosity conditions (e.g., night; twilight; shielded environments). Quinine glows when exposed to UVA light and in the concentrations used is not harmful to the environment. Experimental work was conducted for studying sheet flows in the i) laboratory (using a soil flume), over bare and mulched surfaces, and ii) field, over vegetated and paved surfaces. Flow velocities were estimated based on the injection of a quinine solution into the water flow.  In these experiments, dye and thermal tracer techniques were used as a benchmark for assessing the performance of the quinine tracer. Optical and infrared cameras were used to record the movement of the tracers’ plumes in the flow. The surface velocity of the flow was estimated by tracking the tracers’ plumes leading-edge and calculating their travel distance over a certain time lapse. Overall, the visibility of the quinine tracer was better in comparison to the dye tracer. However, under some circumstances, lower than the visibility of the thermal tracer. Nonetheless, the results show that all three tracers yielded similar estimations of the flow velocities. Therefore, when exposed to UVA light the quinine tracer can be useful to estimate sheet flow velocities over a wide variety of soil and urban surfaces in low luminosity conditions. Despite some inherent limitations of this technique (e.g., invisible under bright light conditions or heavy mulched/vegetated cover; need of a UVA lamp), its main advantage is the high visibility of the quinine fluorescent tracer under UVA light for fade light conditions (e.g., night; twilight; shielded environments such as close conduits), which creates new opportunities for tracer-based surface flow velocity measurements in surface hydrology studies.

How to cite: Zehsaz, S., de Lima, J. L. M. P., de Lima, M. I. P., Isidoro, J. M. G. P., and Martins, R.: Estimating sheet flow velocities using quinine as a fluorescent tracer in low luminosity conditions: laboratory and field experiments, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-515, https://doi.org/10.5194/egusphere-egu23-515, 2023.

EGU23-649 | ECS | Posters on site | HS1.2.1

Near Real-Time Depth Change Monitoring on Inland Water Bodies Using Sentinel-1 and Dynamic World Data 

Utku Berkalp Ünalan, Onur Yüzügüllü, and Ayşegül Aksoy

Monitoring the depth changes in lakes is crucial to understanding hydrological dynamics and water quality changes. In developed countries, the authorities monitor the lake depths regularly; however, it might be different in developing and underdeveloped countries. In this study, we aim to develop a near-real-time SAR-based depth change monitoring system for lakes by focusing on shoreline pixels. For this purpose, we developed a framework using the Sentinel-1 GRD and Sentinel-2 Dynamic World land cover datasets available on the Google Earth Engine. Sentinel-1 data provides us with the necessary temporal resolution for frequent monitoring. For the initial development phase, we consider five ground monitoring stations in Sweden and one in Turkey. The approach starts by detecting water bodies within a selected area of interest using Sentinel-1. Then it extracts shoreline pixels to calculate the change in the VV and VH sigma naught and VV-VH and VV+VH Pauli vectors. Extracted differences are further classified according to the temporally closest Dynamic World data to handle the temporal difference for each land cover type. Next, we eliminate outlier values based on the percentiles, and from the remaining data, we sample each landcover class for modeling. From many of the tested frameworks, we obtained an R2 of 0.79 with Gaussian Process Regression. Currently, in this framework, we observed an underestimation of higher values and an overestimation of lower values within a range of ±0.4 cm. Furthermore, considering the chosen six lakes, we observed a negative correlation between depth change and polarimetric features obtained from samples taken from land covers of grass and flooded vegetation, which is typical for natural lakes. In the second step of the development, we will increase the number of samples by including lakes from Switzerland and further develop the model.

How to cite: Ünalan, U. B., Yüzügüllü, O., and Aksoy, A.: Near Real-Time Depth Change Monitoring on Inland Water Bodies Using Sentinel-1 and Dynamic World Data, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-649, https://doi.org/10.5194/egusphere-egu23-649, 2023.

Monitoring dissolved methane in aquatic ecosystems contributes significantly to advancing our understanding of the carbon cycle in these habitats and capturing their impact on methane emissions. Low-cost metal oxide semiconductors (MOS) gas sensors are becoming an increasingly attractive tool to perform such measurements, especially at the air-water interface. However, the performance of MOS sensors in aquatic environmental sciences has come under scrutiny because of their cross-sensitivity to temperature, moisture, and sulfide interference. In this study, we evaluated the performance and limitations of a MOS methane sensor when measuring dissolved methane in waters. A MOS sensor was encapsulated in a hydrophobic ePTFE membrane to impede contact with water but allow gas perfusion. Therefore, the membrane enabled us to submerge the sensor in water and overcome cross-sensitivity to humidity. A simple portable, low-energy, flow-through cell system was assembled that included an encapsulated MOS sensor and a temperature sensor. Waters (with or without methane) were injected into the flow cell at a constant rate by a peristaltic pump. The signals from the two sensors were recorded continuously with a cost-efficient Arduino UNO microcontroller.. Our experiments revealed that the lower limit of the sensor was in the range of 0.1-0.2 uM and that it provided a stable response at water temperatures in the range of 18.5-28oC. More information at Butturini, A., & Fonollosa, J. (2022). Use of metal oxide semiconductor sensors to measure methane in aquatic ecosystems in the presence of cross‐interfering compounds. Limnology and Oceanography: Methods20(11), 710-720.

How to cite: Butturini, A. and Fonollosa, J.: Metal oxide semiconductor (MOS) sensors to measure methane in aquatic ecosystems. An eficient DIY low  cost application., EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-1221, https://doi.org/10.5194/egusphere-egu23-1221, 2023.

EGU23-1636 | Posters virtual | HS1.2.1

Using the hydrological model for filling the missing discharge data by using multi-site calibration 

Ankit Singh, Hemant Kumar Dhaka, Pragati Prajapati, and Sanjeev Kumar Jha

The river discharge data is one of the most important pieces of information to regulate various water resources, including flood frequency analysis, drought and flood prediction, etc. The missing observer discharge data, even a short gap, influences the whole analysis and gives a totally different result. Filling data gaps in streamflow data is thus a critical step in any hydrological study. Interpolation, regression-based analysis, artificial neural networks, and modeling are all methods for generating missing data. While using the hydrological model to generate the data, we first need to calibrate the hydrological model. The single-site calibration of the hydrological model has its own limitations, due to which it does not correctly predict the streamflow at intermediate gauge locations. This is because, while calibrating the model for the final outlet, we tune the parameters that affect the results for the final outlet only and neglect the intermediate sites' output. In this study, we demonstrate the importance of multi-site calibration and use the calibrated hydrological model to generate the missing data at intermediate sites.

For this study, we selected the Godavari River basin and calibrated it at the final outlet (single-site calibration) and at 18 + 1 outlets (multi-site calibration). The whole basin is divided into 103 subbasins, and the Soil and Water Assessment Tool (SWAT) hydrological model is used for this study. After the successful multi-site calibration, we generated the missing data at 25 different gauging locations. The initial results from single-site calibration (NSE (0.57) and R2 (0.61)) show good agreement between observed and simulated discharge for the final outlet. The multi-site calibration analysis is in progress, and full results will be presented at the conference.

How to cite: Singh, A., Dhaka, H. K., Prajapati, P., and Jha, S. K.: Using the hydrological model for filling the missing discharge data by using multi-site calibration, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-1636, https://doi.org/10.5194/egusphere-egu23-1636, 2023.

EGU23-2681 | Posters on site | HS1.2.1

A low cost real-time kinematic dGPS system for measuring glacier movement 

Kirk Martinez, Jane Hart, Sherif Attia, Graeme Bragg, Marcus Corbin, Michael Jones, Christian Kuhlmann, Elliot Weaver, Richard Wells, Ioannis Christou, and Emily James

Glacier movement has been measured over the years using commercial units such as those from Leica. The aim is to measure point movements on the glacier surface in order to capture fine-grained data about its movement. This can also help to calibrate satellite-based approaches which have much lower resolution. Commercial dGPS recorders cost thousands of Euros so our project is creating a solution using new lower cost dGPS boards which could enable their use by more earth scientists.

The u-blox Zed-F9P based boards from Sparkfun can be used as a base station to send dGPS corrections to “rover” units on the glacier via a radio link. Each measurement is accurate to about 2cm depending on conditions. In our design the radio is used by the rovers to forward good fixes back to the base station, which then uses off-site communications to send the data home. Two types of internet link have been enabled: using a nano-satellite board (by SWARM) and a more traditional GSM mobile phone board (for locations with coverage). Both these boards are also available from Sparkfun – making most of the modules off-the-shelf. However our power supply is optimised to save power and charge the lithium ion battery from a solar panel. A real-time clock chip is used to wake up the system to take readings and transmit data, so the sleep power is only 0.03 mW enabling a year-long lifetime. The whole system is controlled by a Sparkfun Thing Plus SAMD51 which provides the required four serial connections and a circuitpython  environment. The full system will be installed in Iceland in the summer of 2023 and replace the previous prototype based on Swift Piksi Multi units which had shown the measurement principle to be sound.

How to cite: Martinez, K., Hart, J., Attia, S., Bragg, G., Corbin, M., Jones, M., Kuhlmann, C., Weaver, E., Wells, R., Christou, I., and James, E.: A low cost real-time kinematic dGPS system for measuring glacier movement, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-2681, https://doi.org/10.5194/egusphere-egu23-2681, 2023.

EGU23-4844 | Posters on site | HS1.2.1

Quality control of stream water-stage using Hilbert-Huang Transform 

Yen- Chang Chen and Wu-Hsien Hsiao

Hydrological data, especially water stage and discharge, is very important for water resources planning and development, hydraulic structure design, and water resources management. Thus the hydrological data has to be observed and collected regularly and continuously. The hydrological data can be affected by many factors such as people, instruments, and climate. Therefore, the collected hydrological data still need to be subject to quality control and inspection to eliminate unreasonable data to ensure the accuracy and reliability. Traditionally, the quality control and inspection of stream water-stage is mainly manual. The verification of water stage data needs experienced hydrologists to judge the correctness of the data, and cannot be processed automatically. It is time consumed, costly, and labor intensive to process the quality control of stream water stage. Therefore, it is necessary to develop a feasible model to automatically check stream water-stage for providing reliable and accurate hydrological data.

This study applies Hilbert-Huang Transform (HHT) to process stream water-stage. The HHT is composed of Empirical Mode Decomposition (EEMD) and Hilbert transform (HT). The EEMD decomposes stream water-stage into many intrinsic mode functions (IMFs) and a residual. The first IMF component is used for Hilbert transform conversion to obtain the time amplitude energy relationship diagram. The amplitude fluctuation of the corresponding component of the stream water-stage, the amplitude value of the outliers can be revealed. When the amplitude value is larger than usual, there may be outliers, and vice versa. It depends on the threshold that is established in this study as the basis for filtering the incorrect water-stage. Therefore automatically inspecting the water-stage data can be achieved. The model for automatic inspecting procedure developed by this study will greatly reduce the manual quality control, not only shorten the checking time, save manpower, but also provide reliable and correct river water stage data.

How to cite: Chen, Y.-C. and Hsiao, W.-H.: Quality control of stream water-stage using Hilbert-Huang Transform, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-4844, https://doi.org/10.5194/egusphere-egu23-4844, 2023.

EGU23-4878 | Posters on site | HS1.2.1

Trials and design iterations experienced developing a low-cost depth trawl to sample macroplastic through the water column of a tidal river. 

David Higgins, Renata Correia, Hooi Siang Kang, Lee Kee Quen, Tan Lit Ken, Andre Vollering, Stijn Pinson, Thaine H. Assumpção, and Thomas Mani

Understanding the transport behaviour of mismanaged plastic waste in riverine and estuarine environments is growing. However, many studies to date focus on the surface layer transport while a limited number look to measure the vertical distribution of plastic waste within these systems. Factors such as density, shape, the influence of wind and flow velocity can determine the vertical distribution of the plastic waste in a river, but many knowledge gaps remain. With this, and as technology developers move to create innovative river surface focused interception solutions to extract plastic waste, a greater understanding of the transport behaviour of sub-surface plastic debris is required. Here, we present a comprehensive overview of the development stages required to build and deploy a low-cost depth trawl tool designed to sample plastic waste at a depth of up to 5m in a heavily polluted river in Malaysia. Topics covered include tool design concepts, manufacturing methods, onsite testing, river deployment learnings and sampling results. Field data is compiled from over 60 sampling surveys conducted over 14 days in several locations along the Klang River, Malaysia. The depth trawl is mounted to a locally available fishing boat (sampan) and consists of two steel horizontal arms, a steel frame, two winches, cables, weights, five nets, and is operated manually with the assistance of a solar-powered motor. The dimensions of each net are 30cm (W) x 50cm (H) x 100cm (L) with a mesh size of 30mm x 30mm. To ensure that the nets remain aligned vertically during deployment, a weight of 15kg is tied to the bottom of the net system on both sides. Samples were collected every 1 metre to a depth of 5 metres. Each sampling was conducted for 15 minutes, six times per day with an interval of 1 hour between samples to allow for changes in the tide and river flow direction. An ADCP was deployed in parallel to the depth trawl to provide measurements of flow velocity variation at the river surface and with depth. In addition, this paper reviews the depth trawl system’s capabilities and recommendations for further studies and applications in the field.

How to cite: Higgins, D., Correia, R., Kang, H. S., Quen, L. K., Ken, T. L., Vollering, A., Pinson, S., H. Assumpção, T., and Mani, T.: Trials and design iterations experienced developing a low-cost depth trawl to sample macroplastic through the water column of a tidal river., EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-4878, https://doi.org/10.5194/egusphere-egu23-4878, 2023.

EGU23-5922 | Posters on site | HS1.2.1

Effectiveness-assessment of nature-based flood mitigation using networked, low cost DIY environmental monitoring from FreeStation 

Sophia Burke, Arnout van Soesbergen, and Mark Mulligan

FreeStations are mature low-cost, networked, DIY environmental sensors and data loggers, developed since 2014  and now deployed around the world.  Build instructions are open source at www.freestation.org and based on high availability, low cost but accurate and robust components (with builds typically 3% the parts-cost of an equivalent proprietary monitoring systems).  This allows investment in a network of environmental loggers at the cost of a single, proprietary logger.  

FreeStations have been widely deployed in the DEFRA Natural Flood Management (NFM) national trials in the UK, and analytical methods developed to examine the performance of leaky dams, retention ponds, regenerative agricultural practices and other nature based solutions in mitigating flood risk at downstream assets.

These deployments usually consist of FreeStation weather stations: recording rainfall volume, rainfall intensity, air temperature, humidity and pressure as well as solar radiation, wind speed and direction.  The rainfall volume and instantaneous intensity are the most important for NFM studies.  Alongside weather stations, FreeStation sonar-based stage sensors are used, alongside river profile scan from a FreeStation LIDAR, to monitor change in river discharge due to an NFM intervention, relative to discharge at a downstream asset at risk.  Readings are taken at 10-minute intervals over multiple years.

A series of web based methods have been built as part of the FreeStation //Smart: platform to monitor and manage data from deployments and to analyse data to better understand flood mitigation by the key types of intervention.  In testing at more than 10 sites in the UK over a period of 2-3 years per site, large volumes of data have been collected at low cost and in support of local stakeholders during the H2020NAIAD and H2020ReSET projects.  

The data indicate the importance of careful design in leaky debris dams, the limited impact of inline retention ponds and the significant capacity of low-till farming methods to mitigate downstream flooding.  The effectiveness of NFM depends upon the number and scale of interventions, the proportion of the discharge at the downstream asset at risk which they affect (i.e. the downstream proximity of the asset at risk) and the capital and maintenance costs of the interventions. 

Low-cost approaches to environmental monitoring will be critical for developing the evidence base needed to better understand what nature based solutions work, where for water.  Low cost, internet-connected devices are easy to monitor and maintain, low risk and capable of extensive deployment to address the challenge of geographical variability which means that the impacts of specific NFM interventions are highly site specific. 

How to cite: Burke, S., van Soesbergen, A., and Mulligan, M.: Effectiveness-assessment of nature-based flood mitigation using networked, low cost DIY environmental monitoring from FreeStation, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-5922, https://doi.org/10.5194/egusphere-egu23-5922, 2023.

EGU23-8165 | Posters on site | HS1.2.1

Developing a smart sensor network for soil moisture monitoring in forests 

Nikita Aigner, Christine Moos, and Estelle Noyer

Forests play a crucial role in regulating the water content of soils and thus influence runoff formation, but also the susceptibility to drought or forest fires. However, the extent to which forests influence soil moisture is difficult to quantify and depends on several parameters, such as precipitation intensity and duration, and terrain or soil properties. To capture the temporal and spatial variability of soil moisture in forests, large-scale and long-term measurements are necessary. Currently, such measurements are relatively expensive and complex and thus generally lacking or restricted to agricultural areas.  

Our current work focuses on the development of a low-cost soil moisture sensor that uses off the shelf parts and can be deployed at scale to provide continuous long-term measurements. To increase adoption and ensure the digital sustainability of our concept, the project will be released open source to the general public.  

The sensor design is based around an ESP32 microcontroller to manage measurements with capacitive soil moisture sensors. For communication, we leverage the LoRa protocol and use infrastructure provided by the Things Network (TTN). Herein, we present the soft- and hardware architecture of a sensor prototype and results obtained from a proof-of-concept deployment. In addition, we discuss the calibration procedure and evaluation of capacitive soil moisture sensors (in comparison to time-domain reflectometry (TDR) sensors). Finally, we provide an outlook on future developments of our measurement system. The final goal of this project is to deploy sensors in several areas of interest that will allow for gathering data for a better understanding of the interaction of forests and soil moisture content.  

How to cite: Aigner, N., Moos, C., and Noyer, E.: Developing a smart sensor network for soil moisture monitoring in forests, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-8165, https://doi.org/10.5194/egusphere-egu23-8165, 2023.

EGU23-10497 | ECS | Posters virtual | HS1.2.1

Synchronized mapping of water quantity and quality of a reservoir through an unmanned surface vehicle: A case study of the Daljeon reservoir, South Korea 

Kwang-Hun Lee, Shahid Ali, Yena Kim, Ki-Taek Lee, Sae Yun Kwon, and Jonghun Kam

This study developed a synchronized mapping technique for water quantity and quality via an unmanned surface vehicle (USV). The USV with the acoustic doppler current profiler (ADCP) and the multiparameter sonde of water quality sensors (YSI EXO2) was used for identifying spatial and seasonal patterns of the Daljeon reservoir in South Korea. With this technique, we measured bathymetry and nitrate concentration from August 2021 through July 2022 at the high resolution spatial resolution and tested the sensitivity of estimated nitrate loads to spatial variations of input variables (water volumes and nitrate concentrations). Results showed that measured bathymetry and nitrate concentration varies over the water surface of the reservoir and time, which are associated with seasonal variations of temperature and precipitation. Despite weak spatial variations of the nitrate concentration, the water level of the reservoirs showed strong spatiotemporal variations depending on the topography of the reservoir and the  rainfall occurrence. Furthermore, we figured out using the mean for nitrate load was underestimated by -20% of the nitrate load estimates by considering spatial variation. High-resolution bathymetry measurement play a role in estimating nitrate loads with a minor impact of spatial variations of measured nitrate concentrations. We found that rainfall occurrences more likely increase estimated nitrate loads when it accounts for spatially variations of input variables, particularly water volumes. This study proved the potential utility of USV in simultaneously monitoring water quantity and quality for integrative water resource management for sustainably development of our communities.

How to cite: Lee, K.-H., Ali, S., Kim, Y., Lee, K.-T., Kwon, S. Y., and Kam, J.: Synchronized mapping of water quantity and quality of a reservoir through an unmanned surface vehicle: A case study of the Daljeon reservoir, South Korea, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-10497, https://doi.org/10.5194/egusphere-egu23-10497, 2023.

EGU23-11411 | Posters on site | HS1.2.1

Automated ablation stakes to constrain temperature-index melt models 

Andrew D. Wickert, Katherine R. Barnhart, William H. Armstrong, Matías Romero, Bobby Schulz, Gene-Hua Crystal Ng, Chad T. Sandell, Jeff D. La Frenierre, Shanti B. Penprase, Maximillian Van Wyk de Vries, and Kelly R. MacGregor

We developed automated ablation stakes to measure colocated in-situ changes in ice-surface elevation and climatological drivers of ablation. The designs implement open-source hardware, including the Margay data logger, which records information from a MaxBotix ultrasonic rangefinder as well as a sensor to detect atmospheric temperature and relative humidity. The stakes and sensor mounts are assembled using commonly available building materials, including electrical conduit and plastic pipe. The frequent (typically 1–15 minute) measurement intervals permit an integral approach to estimating temperature-index melt factors for ablation. Regressions of ablation vs. climatological drivers improve when relative humidity is included alongside temperature. We present all materials required to construct an automated ablation stake, alongside examples of their deployment and use in Alaska (USA), Ecuador, Patagonia (Argentina), and the Antarctic archipelago.

 

a: Alaska, 2012
b: Alaska, 2013
c: Ecuador, 2016
d: Argentina, 2020
e: Antarctica, 2021

How to cite: Wickert, A. D., Barnhart, K. R., Armstrong, W. H., Romero, M., Schulz, B., Ng, G.-H. C., Sandell, C. T., La Frenierre, J. D., Penprase, S. B., Van Wyk de Vries, M., and MacGregor, K. R.: Automated ablation stakes to constrain temperature-index melt models, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-11411, https://doi.org/10.5194/egusphere-egu23-11411, 2023.

EGU23-11777 | Posters on site | HS1.2.1

A low cost multi-chamber system (“Greenhouse Coffins”) to monitor CO2 and ET fluxes under semi-controlled conditions: Design and first results 

Mathias Hoffmann, Wael Al Hamwi, Matthias Lück, Marten Schmidt, and Maren Dubbert

Determining greenhouse gas (GHG) fluxes, water (ET) fluxes and their interconnectivity within the soil-plant-atmosphere-intersphere is crucial, not only when aiming to find solutions for current agricultural systems to mitigate the global climate crises but also to adapt them to related challenges ahead, such as more frequent and severe droughts. In a first attempt for a better understanding, often laboratory and/or greenhouse pot experiments are performed, during which gas exchange is predominately measured using especially manual closed chamber systems. Commercially available systems to determine gas exchange in terms of CO2 and ET are, however, costly and measurements itself labour-intensive. This limits the amounts of variables to be studied as well as possible repetitions during a study. Additionally, it resulted in the long-term focus on agroecosystems of the northern hemisphere while agroecosystems of sub-Saharan Africa as well as Southeast Asia are still being underrepresented.

We present an inexpensive (<1.000 Euro), Arduino based, multi-chamber system to semi-automatically measure 1) CO2 and 2.) ET fluxes. The systems consists of multiple, self-sufficient, closet-shaped PVC “coffins”. The “coffins” a closed by a frontal door and periodically ventilated through a sliding window. Relays connected to the microcontroller are used to steer closure/opening (linear actuator) and ventilation (axial fans). CO2 and ET fluxes are determined through the respective concentration increase during closure by a low-cost NDIR CO­2 (K30FR; 0-10,000 ppm, ± 30 ppm accuracy) and rH sensor (SHT-41). Parallel measurements of relevant environmental parameters inside and outside the “coffins” are conducted by DS18B20 (temperature) and BMP280 (air pressure) sensors. Sensor control, data visualization and storage, as well as steering closure/opening and ventilation is implemented in terms of a wifi and bluetooth enabled, socket powered (9V), compact microcontroller (D1 RS32) based logger unit. Here, we present the design, and first results of the developed, low-cost multi-chamber system. Results were validated against results of customized CO2 and ET measurement systems using regular scientific sensors (LI-COR 850) and data logger components (CR1000), connected to each “coffin” by a multiplexer.  Flow-meter were used for measurement synchronization.

How to cite: Hoffmann, M., Al Hamwi, W., Lück, M., Schmidt, M., and Dubbert, M.: A low cost multi-chamber system (“Greenhouse Coffins”) to monitor CO2 and ET fluxes under semi-controlled conditions: Design and first results, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-11777, https://doi.org/10.5194/egusphere-egu23-11777, 2023.

EGU23-12622 | ECS | Posters on site | HS1.2.1

Water user Fab Labs: co-design of low-tech sensors for irrigated systems 

Paul Vandôme, Crystele Leauthaud, Simon Moinard, Insaf Mekki, Abdelaziz Zairi, and Gilles Belaud

Mediterranean agriculture is facing the challenge to produce sustainably with a water resource under pressure. As irrigated areas expand in response to increasing vulnerability to drought, it is essential to support water users towards better agricultural water management. We set up two Fab Labs on the shores of the Mediterranean (France and Tunisia) to bring together water users around a collective project: co-constructing innovations to address local water management issues. A range of low-tech, low-cost and open source IoT-based sensors emerged from this process. The technologies were tested with users during the 2022 irrigation season. The aim of this study is to provide feedback on this participatory method as a facilitator for creating and sharing innovation in rural territories and to discuss the opportunities, benefits and limitations related to the use of these new technologies. We believe that this work contributes to make the measurement of water flows - and thus their understanding and better management - more accessible to the agricultural sector.     

How to cite: Vandôme, P., Leauthaud, C., Moinard, S., Mekki, I., Zairi, A., and Belaud, G.: Water user Fab Labs: co-design of low-tech sensors for irrigated systems, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-12622, https://doi.org/10.5194/egusphere-egu23-12622, 2023.

EGU23-13072 | ECS | Posters on site | HS1.2.1

Precipitation Measurement from Raindrops’ Sound and Touch Signals 

Seunghyun Hwang, Jinwook Lee, Jeemi Sung, Hyochan Kim, Beomseo Kim, and Changhyun Jun

This study proposes a novel method for rainfall intensity estimation from acoustic and vibration data with low-cost sensors. At first, a precipitation measurement device was developed to collect sound and touch signals from raindrops, composed of Raspberry Pi, a condenser microphone, and an accelerometer with 6 degrees of freedom. To figure out whether rainfall occurred or not, a binary classification model with the XGBoost algorithm was considered to analyze long-term time series of vibration data. Then, high-resolution acoustic data was used to investigate the main characteristics of rainfall patterns at a frequency domain for the period when it was determined that rainfall occurred. As a result of the Short Time Fourier Transform (STFT), the highest frequency, mean and standard deviation of amplitudes were selected as representative values for minute data. Finally, different types of regression models were applied to develop the method for rainfall intensity estimation from comparative analysis with other precipitation measurement devices (e.g., PARSIVEL, etc.). It should be noted that the new device with the proposed method functions reliably under extreme environmental conditions when the estimated rainfall intensity was compared with measured data from ground-based precipitation devices. It shows that low-cost sensors with sound and touch signals from raindrops can be effectively used for rainfall intensity estimation with easy installation and maintenance, indicating a strong possibility of being considered in a wide range of areas for precipitation measurement with high resolution and accuracy

Acknowledgement

This work was supported by the National Research Foundation of Korea(NRF) grant funded by the Korea government(MSIT) (No. NRF-2022R1A4A3032838).

How to cite: Hwang, S., Lee, J., Sung, J., Kim, H., Kim, B., and Jun, C.: Precipitation Measurement from Raindrops’ Sound and Touch Signals, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-13072, https://doi.org/10.5194/egusphere-egu23-13072, 2023.

EGU23-14370 | Posters on site | HS1.2.1

Monitoring an ephemeral stream with a Teensy 3.2 + audio shield to determine water level only from the noise of a stream 

Linus Fässler, Natalie Ceperley, Peter Leiser, and Bettina Schaefli

River networks in the Alps are very complex and hold many unanswered research questions. For example, various assumptions must be made to when studying tributaries and small rivers. Namely, there is not a widely accepted tool to measure streamflow in small, mountain streams that can overcome their specific challenges affordably without large installations. For example, alteration between extremely high and no discharge volume is characteristic of intermittent rivers and ephemeral streams (IRES). Conventional measuring devices all require streambed installation, which exposes them to displacement or destruction by abruptly rising water levels. One solution, thus, is to remove the sensor from the streambed and measure from a distance. We have experimented with an acoustic sound recorder mounted above the stream as an alternative tool to assess water level. We designed a low-cost audio sensor powered by a microcontroller with an audio shield specifically for recording IRES. To ensure reproducibility, we used Arduino for programming the Teensy 3.2. Images of the water level in an IRES were simultaneously captured when possible (daylight) and used for calibration. The water level visible in the images correlated well with that determined from the audio recordings from our self-developed audio sensor (R2 = 95%). Based exclusively on the audio recording of an IRES, we can obtain a time series of the water level, at least when water was present. We are currently unable to determine consistently whether water is present nor state with certainty when the streambed is dry based solely on acoustic data. Nevertheless, this new sensor allows us to measure an alpine channel network at more locations and over longer time periods than previously feasible.

How to cite: Fässler, L., Ceperley, N., Leiser, P., and Schaefli, B.: Monitoring an ephemeral stream with a Teensy 3.2 + audio shield to determine water level only from the noise of a stream, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-14370, https://doi.org/10.5194/egusphere-egu23-14370, 2023.

The development of artificial reservoirs plays a considerable role in regulating the spatial and temporal distribution of irrigated rainfall and guaranteeing sustainable agricultural development. Many studies have used the area-storage relationship to obtain the storage capacity of on-farm reservoirs (OFRs), but it does not work for OFRs with persistent water surface area. In this study, we proposed an effective method to estimate the water storage of irrigated OFRs by combining multi-source remote sensing data and ground observation. We quickly derived the location of irrigated OFRs by using seasonal characteristics of irrigated OFRs and obtained high-precision water surface area using an object-oriented segmentation. We estimated water storage of irrigated OFRs by combining three different ways (i.e., Lidar-based, ground observation-based (photos), and surface area-based). The method performs well in three aspects, i.e., identifying on-farm reservoirs, extracting water surface area, and calculating water storage. The accuracy of identification reaches 94.1%, and the derived water area agrees well with the surveyed results, i.e., an overall accuracy of 97.8%, the root mean square error (RMSE) and the mean absolute errors (MAE) are 962 m2 and 766 m2, respectively. The obtained water storage is reliable using three different ways (i.e., the area-storage, Lidar-based, and photo observations-based methods), with accuracy of 98.8%, 95.2%, and 94.1%, respectively. The proposed method enables monitoring of the storage of multiple types of irrigated OFRs, particularly the photo observation-based method can deal with the storage of OFRs with persistent water areas, showing huge potential to promote irrigated water resource utilization efficiency.

How to cite: wang, Y.: Monitoring water storage of on-farm reservoirs using remote sensing and ground observation, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-15372, https://doi.org/10.5194/egusphere-egu23-15372, 2023.

Hydrology is still one of the most data scarce natural sciences. The large number of variables to measure, their extreme spatiotemporal gradients, and the often harsh and hostile environmental conditions all contribute to this issue. This challenge is even more pronounced in remote and extreme environments such as the tropics, and mountain regions, where the need for robust data is most acute.

Many new and emergent technologies can help with building more cost-effective, robust, and versatile hydrological monitoring systems. However, the speed at which these new technologies are being incorporated in commercially available systems is slow and dictated by commercial interests and bottlenecks.

An alternative solution is for scientists to build their own systems using off the shelf components. Open-source hardware and software, such as the Arduino and Raspberry Pi ecosystems, make this increasingly feasible. As a result, a plethora of global initiatives for open-source sensing and logging solutions have emerged.

But despite these new technologies, it remains a major challenge to build open-source solutions that equal the reliability and robustness of the high-end commercial systems that are available on the market. Sharing experiences, best practices, and evidence on the real-world performance of different designs may help with overcoming this bottleneck.

In this contribution, I summarize the experience gained from developing and operating over 300 open-source data loggers, built around the Riverlabs platform. This platform is mostly a compilation of existing open-source hardware and software components and solutions, which were refined further and tweaked for robustness and reliability in extreme environments. Our loggers have been installed in locations as diverse as Arctic Norway, the high Andes of Peru and Chile, the Nepalese and Indian Himalayas, the Somali desert, and the Malaysian rainforest, providing a wide range of real-world test-cases and performances.

How to cite: Buytaert, W.: Towards a robust, open-source logging platform for environmental monitoring in challenging environments: the Riverlabs toolbox, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-15989, https://doi.org/10.5194/egusphere-egu23-15989, 2023.

EGU23-17527 | ECS | Posters on site | HS1.2.1

Design of an affordable and highly flexible IoT station for multiple gas concentration monitoring 

Francesco Renzi, Flavio Cammillozzi, Giancarlo Cecchini, Alessandro Filippi, and Riccardo Valentini

The air quality monitoring is a core topic for European environmental policies and worldwide. At the same time technologies such as electrochemical or NDIR gas sensors became affordable and easy to implement in a customized design. A highly flexible monitoring station has been designed and build in order to obtain a customizable and affordable device. It is composed of two boards, one in charge of connectivity and processing while the other allows to insert up to 11 gas sensors. Such number is achieved through the use of three multiplexers that allow to spare input pins of the processor. Moreover the flexibility at the moment is achieved using sensors with the same form factor but adapters are under development to increase the adaptability of the system, both hardware and software. An Arduino MKR zero runs the application that can be run in three different modes: single measurement, time driven or position driven. The last feature is obtained through an optional on-board U-blox GNSS module that allows to georeference the performed measurements. This mode is mainly used when the measurement cell is applied on moving object, such as drones. The system is able to send the data collected and receive commands using MQTT protocol (HiveMQ broker) through a NB-IoT connection and interact with the user from an online dashboard created using Thingsboard. The use of the MQTT protocol allows to send the data to multiple endpoints if the data should be provided also to third parties. Moreover, the data and some parameters are also saved on a sd card. All the system is built on stand alone boards to achieve easy maintaince of the system and to allow a rapid change in the used technology (a plug and play LoRaWan module is under development). Being a multi-application platform, price of the device is of course highly dependent on the chosen set of sensors thus, in the end, on the application itself (i.e. Air pollution or gas emission in barns). To sum up, the device described is a possible solution for an affordable gas concentration measurement system that can be adapted to fit a large variety of use cases combining software and hardware solutions.

How to cite: Renzi, F., Cammillozzi, F., Cecchini, G., Filippi, A., and Valentini, R.: Design of an affordable and highly flexible IoT station for multiple gas concentration monitoring, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-17527, https://doi.org/10.5194/egusphere-egu23-17527, 2023.

EGU23-1088 | Orals | HS1.2.2

Lessons learned from catchment observatory and network design in the UK, rest of Europe and North-America 

Gemma Coxon, John P Bloomfield, Wouter Buytaert, Matt Fry, Gareth Old, and Thorsten Wagener

Many countries fund catchment observatories and networks to provide observational data, test models and hypotheses, discover new insights, catalyse the development of new technologies and enhance interdisciplinary collaboration. These catchment networks provide a wealth of observational data, yet synthesising information across catchment observatories to produce process-based understanding is challenging. To generalise findings from place-based studies, we need greater synthesis across catchment networks and thus careful consideration of the design and topology of catchment observatories and monitoring networks.

In this paper, we collate information from 80 catchment observatories/networks and conduct 21 questionnaires with project leads with the aim of reviewing the strengths and weaknesses of catchment observatories to provide recommendations that can inform future catchment observatory and network design. The catchment observatories encompass a wide range of flow regimes, science questions and spatial/temporal scales with 25, 33 and 22 observatories from the UK, Europe, and North America respectively. Most catchment observatories in the monitoring catalogue are concentrated in upland catchment systems monitoring flashy flow regimes, with very few focused on lowland systems and no catchment observatories focused on urban catchments. The choice of catchment observatory location was focused upon logistics and catchment characteristics, with logistics and the day-to-day running of the observatory highlighted as the aspect catchment observatory programme managers found most difficult. Many interviewees noted that the design of the observatory was a key phase in planning and an aspect they would have done differently.

Finally, we recommend key design guidelines for future catchment observatory and networks. This includes the need for a scoping and planning phase, community co-designed, digital infrastructure that enables FAIR data provision, and flexible and extensible catchment topology. Critically, knowledge transfer needs to be built in from the beginning of catchment observatories to enable transferability of new insights and understanding across linked catchment networks to tackle grand challenges within hydrology.

 

How to cite: Coxon, G., Bloomfield, J. P., Buytaert, W., Fry, M., Old, G., and Wagener, T.: Lessons learned from catchment observatory and network design in the UK, rest of Europe and North-America, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-1088, https://doi.org/10.5194/egusphere-egu23-1088, 2023.

EGU23-4589 | Orals | HS1.2.2

Digital Twin Water Management Platform - Innovative approach for optimal water management 

Jingon Kim, Kichul Kim, Junghwan Lee, Mookhyunk Kwon, Hyunjin Kim, and Youngsik Jo

Recently, digitalization has impacted drought and flood forecasting systems, and makes the application of technologies and advanced data processing techniques in the water management field possible. Especially, digital twin in the field of water management aims to effectively diminish unprecedented water-related issues such as floods and droughts using 3D objects and high-resolution spatial data. Climate change effects are expected to increase flood and drought risk through more frequent heavy precipitation and global temperature rise, and the water disaster sector is so complex, dynamic, and unpredictable that requires sophisticated management systems. The digital approaches showed effective prediction and decision-making support. This paper presents the state-of-the-art of digital twin concepts along with different digital technologies and techniques in water management contexts. The digital twin platform developed by K-water is a virtual representation of water management for dam operation and urban flood warning with water-related data. It presents a general framework of the digital twin in risk management, optimal operation, and decision-making in the water management and disaster forecasting field. This review also described the water data management, modeling including artificial intelligence, Radar, CCTV, rainfall-runoff module, analysis, prediction, and communication aspects of a digital twin. Digital twin platforms can support decision-makers as the next generation of digitalization paradigm by continuous and real-time water management of the cyber world and simulating the various events in the cyber world.

Keywords: Digital Twin, Dam Operation, River, Spatial Data, AI, Urban Flood

How to cite: Kim, J., Kim, K., Lee, J., Kwon, M., Kim, H., and Jo, Y.: Digital Twin Water Management Platform - Innovative approach for optimal water management, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-4589, https://doi.org/10.5194/egusphere-egu23-4589, 2023.

EGU23-4765 | ECS | Posters virtual | HS1.2.2

Non-contact Entropy-based flow Estimation in Himalayan Rivers 

Abhishek Kumar and Manoj Kumar Jain

Rapidly collected river discharge data can be used for flood forecasts, hydraulic structure design, and impromptu response during floods. This calls for the monitoring of both water level and velocity at the same time, which is not feasible using conventional invasive methods. Non-contact techniques like doppler radar and satellite remote sensing techniques are the sole options. Doppler radar sensors are gaining popularity in the recent decade due to their accuracy and user-friendly operation. The study was conducted using data collected at two gauging sites at Devprayag on Bhagirathi and Ganga, two significant Himalayan Rivers. This study compares the observed discharge measured using a current meter and ADCP with the entropy-based discharge estimated using radar telemetry data for water level and surface velocity. Radar-derived water level and one-point surface velocity observations were used to estimate the discharge using probability-based Shannon and Tsallis Entropy laws. The discharge varied from 77.09 to 4265.4 cumec, while the surface velocities ranged from 0.283 to 8.35 m/s. The estimated discharges using radars were compared with observed discharges using Goodness-of -fit statistics which showed a good agreement between observed and estimated discharges as well as velocities, suggesting that radars can be effectively used to estimate real-time discharge for its improved applications in Himalayan mountainous rivers.

How to cite: Kumar, A. and Jain, M. K.: Non-contact Entropy-based flow Estimation in Himalayan Rivers, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-4765, https://doi.org/10.5194/egusphere-egu23-4765, 2023.

EGU23-5779 | ECS | Posters on site | HS1.2.2

Reducing the operator effect in LSPIV image-based discharge measurements 

Guillaume Bodart, Jérôme Le Coz, Magali Jodeau, and Alexandre Hauet

The operator effect is a prominent error source in image-based velocimetry methods. The LSPIV method is known to be sensitive to the parameters and choices of the user, as shown in the literature and emphasized by the results of a video gauging intercomparison, the Video Globe Challenge 2020 (VGC2020) (Le Coz et al., 2021). The intercomparison was carried out during the COVID-19 lockdown of spring 2020 and involved 15 to 23 participants using the LSPIV method among other techniques on 8 videos representative of the diversity of river gauging conditions and imaging viewpoints. Each video came with a discharge reference and associated uncertainty.

An in depth investigation of the intercomparison results has been carried out to identify the most sensitive parameter(s) for each video and also to review the common setting mistakes (cf. Bodart et al., 2022). The investigation highlighted the strong impact of the image temporal sampling (extraction framerate) and of the velocity filtering on the discharge errors. The ortho-rectification and the surface coefficient were also found to be impacting in given cases.

Based on these observations, several assistance tools and automated filters are proposed to reduce the operator effect. They are evaluated on the intercomparison dataset. The assistance tools use available information (e.g. transect data) or basic user inputs (e.g. manual spotting of some velocities) to determine the optimal extraction framerate, grid points and searching area (SA) for LSPIV computation. The sequence of automated filters is built for the specific context of discharge measurement: spatial coherency of the velocities in a local neighborhood and temporal coherency of the velocities computed at a point. These velocity filters are systematic and do not require any input from the user.

The application of the assistance tools and automated filters to the intercomparison dataset leads to a significant improvement of the results. On the eight videos, the mean interquartile range of the percent error initially at 17% is reduced to 2% and the mean median of the percent error initially at -9% is reduced to 0.6% with the assistance tools and filters. The results are encouraging and can be implemented in software tools for the operational deployment of the LSPIV method for discharge measurement.

Le Coz, J., Hauet, A., and Despax, A. (2021). The Video Globe Challenge 2020, a video streamgauging race during the Covid-19 lockdown, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-2116, https://doi.org/10.5194/egusphere-egu21-2116, 2021

Bodart, G., Le Coz, J., Jodeau, M., and Hauet, A.: Quantifying the operator effect in LSPIV image-based velocity and discharge measurements, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-4457, https://doi.org/10.5194/egusphere-egu22-4457, 2022.

How to cite: Bodart, G., Le Coz, J., Jodeau, M., and Hauet, A.: Reducing the operator effect in LSPIV image-based discharge measurements, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-5779, https://doi.org/10.5194/egusphere-egu23-5779, 2023.

EGU23-6587 | Posters on site | HS1.2.2

Bayesian calibration of a 1D hydrodynamic model used as a rating curve in a tidal river: Application to the Lower Seine River, France 

Felipe Mendez Rios, Jérôme Le Coz, Benjamin Renard, and Theophile Terraz

Hydrometric stations may be influenced by the sea tide, disrupting the stage-discharge relation and making it difficult to estimate discharge through a traditional rating curve. Twin-gauge stage-fall-discharge (SFD) rating curves, based on a flow friction equation and stage and water slope measurements, are a possible alternative, but they were found to perform poorly when the tide effect is strong. To capture the complex flow dynamics, including flow reversal, an approach via a 1D hydrodynamic model is proposed.

To set up the model, the cross-sectional geometry, friction coefficient, upstream discharge and downstream water level are required. In hydrodynamic modelling, the friction coefficients are the main calibration parameters and spatial changes of roughness combined with unsteady flow make their manual calibration difficult. Moreover, the understanding and quantification of uncertainties associated with data and model is an important step of the calibration process. Therefore, an automatic calibration of friction coefficients is proposed via Bayesian inference. In terms of numerical tools, the selected 1D hydrodynamic code is Mage, developed by INRAE, solving the 1D Saint-Venant equations for subcritical, transient flows. Likewise, the Bayesian Modeling (BaM) framework (https://github.com/BaM-tools) is used to specify prior information and estimate friction coefficients and their uncertainty, using stage and discharge observations.

The case study is the Lower Seine River in France, because it comes as a simple hydraulic model with a strong tidal effect with gauging campaigns and stage records available. Discharge time series of the Seine at Poses and of the Eure, the only significant tributary, are specified as upstream boundary conditions.  The downstream boundary condition is the stage time series of the Seine at Saint-Léonard, reflecting the tidal signal. Calibration data include stage records at different stations and times, and ADCP discharge measurements at Rouen during several tidal cycles.

For all reaches, a lognormal distribution with 95% probability interval [33; 49] is used as a prior for the Strickler coefficient. Bayesian estimation then provides their posterior distributions, represented by a large number of samples generated by means of a Markov Chain Monte Carlo (MCMC) algorithm. These samples can be used to identify optimal “maxpost” coefficients (maximizing the posterior density), but also to quantify and propagate their uncertainty. Thereafter, a propagation is performed to estimate the stage and discharge series of all cross-sections along with their uncertainty.

This study aims to provide an alternative solution for the continuous monitoring of discharge from stage records and upstream discharges in tidal rivers in order to improve flood forecasting, warning systems and the understanding of tidal-influence on hydrometric stations.

How to cite: Mendez Rios, F., Le Coz, J., Renard, B., and Terraz, T.: Bayesian calibration of a 1D hydrodynamic model used as a rating curve in a tidal river: Application to the Lower Seine River, France, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-6587, https://doi.org/10.5194/egusphere-egu23-6587, 2023.

EGU23-6745 | Posters on site | HS1.2.2

Image-based methods for real-time water level estimation 

Anette Eltner, Pedro Zamboni, Ralf Hedel, Jens Grundmann, and Xabier Blanch

Obtaining real-time water level estimations is crucial for effective monitoring and response during emergencies caused by heavy rainfall and rapid flooding. Typically, this type of monitoring can be a difficult task, requiring river reach preparations and specialized equipment. Moreover, in extreme flood events, standard observation methods may become ineffective. This is why the possibility of developing low-cost, automatic monitoring systems represents a significant advancement in our ability to monitor river courses and allow emergency teams to respond appropriately.

Image-based methods for water level estimation facilitate the development of a low-cost river monitoring strategy in a quick and remote approach. These techniques are faster and more convenient regarding the setup than traditional water stage monitoring methods, allowing us to efficiently monitor the river from different locations with a cost-effective approach. By increasing the density of the observation network, we can improve flood warning and management.

The approach presented involves placing cameras in secure locations to capture images of the river, for which we have previously modelled the terrain in 3D using Structure from Motion (SfM) algorithms supported by GNSS data. With the images obtained every 15 minutes, we perform a Convolutional Neural Network (CNN) segmentation based on artificial intelligence algorithms that allow us to automatically extract the contours of the water surface area. In this study, two different neural network approaches are presented to segment water in the images.

Using a photogrammetric strategy, we reproject the water line extracted by the AI on the 3D model of the scene. This reprojection is also supported by the use of a keypoint detection neural network that allows us to accurately identify the ground control points (GCPs) observed in the images captured by the surveillance camera. This approach allows us to automatically assign to each image the real coordinates of the GCPs and subsequently estimate the camera pose.

This AI segmentation and automatic reprojection into the 3D model has allowed us to generate a robust centimetre-accurate workflow, capable of estimating the water level in near-real time for daylight conditions. In addition, the automatic detection of the GCP has permitted to obtain automatic water level measurements over a longer period of time (one year). This approach represents the basis for obtaining other river monitoring parameters, such as velocity or discharge, which allow a better understanding of river floods and represent key steps for the development of early warning systems for flood events.

How to cite: Eltner, A., Zamboni, P., Hedel, R., Grundmann, J., and Blanch, X.: Image-based methods for real-time water level estimation, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-6745, https://doi.org/10.5194/egusphere-egu23-6745, 2023.

EGU23-6936 | Posters on site | HS1.2.2

Image-based velocity estimations under different seeded and unseeded river flows 

Silvano F. Dal Sasso, Robert Ljubicic, Alonso Pizarro, Sophie Pearce, Ian Maddock, and Salvatore Manfreda

The use of image velocimetry techniques for river monitoring has been increasing in the last few years, but there are some limitations to be solved related mainly to natural environmental conditions and operative framework (Dal Sasso et al., 2021). Along with these issues, the need for surface tracking features or homogeneously distributed materials across the cross-section represents one of the challenges for outdoor applications. In a natural environment, flows can present low seeding densities or locally distributed tracer clusters. These conditions can introduce a high variance and underestimate the flow velocity field, especially near the riverbanks.

In this work, the Farnebäck dense optical flow method (Farnebäck 2003) implemented in SSIMS-Flow software (Ljubicic, 2022) was tested and compared with LSPIV technique (Thielicke et al., 2021) to estimate surface flow velocities under different seeding conditions. The application was carried out on the Arrow River (UK) along two meandering river reaches during low-flow conditions. Four different seeding conditions were experimented from low (natural) to high (artificial) seeding density of tracers . Tracers were manually distributed onto the water surface and videos were acquired from DJI Phantom 4 Pro. Seeding metrics were used to estimate seeding conditions including: mean tracer area, seeding density, spatial tracer distribution, and the SDI index (Pizarro et al., 2020). Conventional velocity measurements were used as benchmark purposes along various transects.

This study highlighted the good performances of the two tested image velocimetry methods, with results comparable to traditional techniques. On the one hand, the Farnebäck optical flow method proved to be more sensitive to changing setting parameters (e.g., feature extraction rate) with respect to LSPIV. On the other hand, optical flow showed low sensitivity to seeding density (error reduction 30-40%). This is due to the capacity of the Farnebäck method integrated with an ad-hoc pooling technique for spatial velocity averaging to represent surface velocity under sporadic and uneven seeding (e.g., near the convex bank).

References

Dal Sasso, S. F., Pizarro, A., Manfreda S. (2021). Recent Advancements and Perspectives in UAS-Based Image Velocimetry. Drones 5, 3: 81.

Farnebäck, G. (2003). Two-frame motion estimation based on polynomial expansion, Scandinavian conference on Image analysis. Springer, Berlin, Heidelberg.

Ljubicic, R. (2022). SSIMS-Flow: UAV image velocimetry workbench, https://github.com/ljubicicrobert/SSIMS-Flow

Pizarro, A., Dal Sasso, S.F., Manfreda, S. (2020). Refining image-velocimetry performances for streamflow monitoring: Seeding metrics to errors minimization. Hydrol. Process. 2020, 34, 5167–5175.

Thielicke, W., Sonntag, R. (2021). Particle Image Velocimetry for MATLAB: Accuracy and Enhanced Algorithms in PIVlab. Journal of Open Research Software, 9, Ubiquity Press, 2021.

How to cite: Dal Sasso, S. F., Ljubicic, R., Pizarro, A., Pearce, S., Maddock, I., and Manfreda, S.: Image-based velocity estimations under different seeded and unseeded river flows, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-6936, https://doi.org/10.5194/egusphere-egu23-6936, 2023.

EGU23-6984 | Orals | HS1.2.2

Quantifying high-flow rating shifts due to unusual floodplain roughness during the July 2021 European flood 

Jérôme Le Coz, Michel Lang, Stéphanie Poligot-Pitsch, and Bruno Janet

In July 2021, several western European countries were stricken by extreme floods due to exceptional rainfall events. In North-Eastern France overbank flows started to occur in several rivers on July 14th. The local field hydrologists of the national hydrological service (Vigicrues) managed to conduct mobile-boat ADCP discharge measurements during the floods at many hydrometric stations. They often observed dramatic high-flow rating shifts, typically with measured discharges being 20% to 60% smaller than the discharges computed from the stage-discharge rating curves. Such unusual rating shifts are substantially larger than the uncertainty of the ADCP discharge measurements (5%-10%). To avoid biases in flood forecast, the rating curves had to be recalibrated with limited information on the fly, which was uncomfortable. The local field hydrologists reported that the rating shifts may be due to the floodplain vegetation being very different from the winter conditions of the flood discharge measurements used to build the high-flow ends of the rating curves. In July 2021 indeed, floodplains were covered with high summer crops that had not been harvested due to the unusually cold and rainy weather.

To test this assumption on a hydraulic basis, the rating curves of seven stations on the rivers Aisne, Oise, Helpe Majeure, Chiers and Loison in North-Eastern France were re-analysed using the Bayesian method BaRatin implemented in the BaRatinAGE open-source software. At all of these stations, the identified controls include the main channel (and possibly other low-flow controls) and a relatively wide, rural floodplain. For each station, two rating curves and their uncertainty envelopes are computed: the “normal” rating curve using all valid discharge measurements except those of the July 2021 flood, and the “July 2021” rating curve using no flood discharge measurements but those of the July 2021 flood. For the “July 2021” rating curve, the prior height (offset) of the floodplain is usually taken as the posterior (calibrated results) of the “normal” rating curve, but the coefficient of the floodplain control is calibrated using the July 2021 ADCP discharge measurements. The obtained rating curves are consistent with the rating curves estimated manually by the local field hydrologists. The floodplain friction factors  estimated by BaRatin for the “July 2021” rating curve are decreased by a factor of 1.6 to 14, typically (i.e. Strickler coefficients from 15-20 m1/3/s to 2-10 m1/3/s), which is spectacular but consistent with available look-up tables for friction factors in bare or vegetated fields.

The proposed Bayesian analysis appears useful for field hydrologists to evaluate the possible extent of rating shifts due to unusual floodplain roughness at their stations, and to be prepared for the recalibration of their rating curves would an overbank flood occur outside the winter season again. It is also a convenient way for them to inform and prepare the flood forecasters on the causes and occurrence of such rating shifts, and on the related discharge uncertainty they would have to take into account.

How to cite: Le Coz, J., Lang, M., Poligot-Pitsch, S., and Janet, B.: Quantifying high-flow rating shifts due to unusual floodplain roughness during the July 2021 European flood, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-6984, https://doi.org/10.5194/egusphere-egu23-6984, 2023.

EGU23-7073 | Posters on site | HS1.2.2

Comparing ADCP inter-comparison results using an automated post-processing tool 

Blaise Calmel, Jerôme Le Coz, Hauet Alexandre, Despax Aurélien, and David Mueller

The moving-boat Acoustic Doppler Current Profiler (ADCP) gauging method is extensively used to measure the discharge of rivers and canals. Inter-comparison of ADCP measurements are necessary not only to validate the instruments and their deployment, but also to study the discharge measurement uncertainty. Uncertainty estimates provided by the propagation methods cannot be validated for in situ conditions because of the complexity of the ADCP data workflow and the uncertainty of discharge references in rivers and canals. To solve this issue, a complementary approach to uncertainty propagation methods is the repeated measures experiments, also known as inter-laboratory comparisons. ADCP inter-comparisons have been done for decades and with very different conditions. These data sets are precious in order to test and validate uncertainty propagation methods.

The OURSIN ADCP uncertainty analysis is validated using empirical uncertainty estimates on inter-comparison experiment. This propagation method has been implemented in the QRevInt software which provides an ADCP data quality review. QRevInt is developed by Genesis HydroTech LLC (Mueller, 2021) with the guidance and contributions from an international board of hydrological agencies. QRevInt helps to clean ADCP measurements from avoidable errors and to homogenize the discharge computations irrespective of the instrument manufacturer and model.

However, post-processing inter-comparison results is a long and complicated process particularly if users want to determine and quantify uncertainty sources. There are as many practices as there are hydrometric services. Uncertainty is an indispensable component of discharge measurement and should be estimated for as many measurements as possible. To popularize these practices and homogenize them, a user-friendly tool has been developed.

From raw ADCP measurements, it applies QRevInt post-process quality analysis, the OURSIN uncertainty propagation method, and the empirical uncertainty computation based on the repeated-measures experiment. The tool applies Grubbs and Cochran statistical tests to validate the measurement selection. It returns tables with a row for each measurement with information, such as, discharge and uncertainty decomposition from QRevInt. It also returns an overview of the inter-comparison with graphs of the discharge and its uncertainty among measurements, computed uncertainty, and empirical uncertainty. The tool allows replaying data with homogeneous parameters and users can manually exclude a measurement if it does not seem consistent. The tool will be open source and freely available.

Beyond the operational application, it could be used to replay historical inter-comparisons. With an inter-comparison database, it will be possible to study diverse types of rivers to improve and validate uncertainty estimation in various conditions. A first synthesis is proposed from one inter-comparison data set and will be extended to as much data as possible in the future.

How to cite: Calmel, B., Le Coz, J., Alexandre, H., Aurélien, D., and Mueller, D.: Comparing ADCP inter-comparison results using an automated post-processing tool, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-7073, https://doi.org/10.5194/egusphere-egu23-7073, 2023.

EGU23-9946 | ECS | Posters on site | HS1.2.2

Application of optical Particle Tracking Velocimetry (PTV) to determine continuous discharge time series 

André Kutscher, Jens Grundmann, Anette Eltner, Xabier Blanch, and Ralf Hedel

The measuring of flood events is associated with many challenges. Among them is the determination of flow velocities for the derivation of discharge. Most of the applied methods for velocity determination the disadvantage that they work in direct contact with water. This often makes measuring under critical flow conditions dangerous. Optical measurement methods have a great advantage because they can work remotely, i.e., without water contact.

For representative discharge measurements, flow velocity measurements over the entire width of the river cross-section are required. This is a major challenge in the application of PTV, because visible particles must be present across the entire cross-section, which is not always the case. The potential measurement gaps in the surface velocity distribution have a negative effect on the quality of the discharge determination. Because optical measurement methods are relatively new in hydrology, there is not yet a standardised procedure with which the discharge can be determined. 

The "OptiQ" method presented here is an approach for determining discharge using PTV. This method is based on the continuity equation, which is dependent on two variables, the flow area and the mean flow velocity. The challenge here is to determine the depth-averaged flow velocity, because PTV is used to determine the surface velocity. To get the depth-averaged flow velocities, the PTV results are averaged over a transect and converted using a velocity coefficient. The arithmetic mean, the velocity area method (DIN EN ISO 748:2008-02) and the moving average are considered as averaging methods. A statistical approach was chosen for closing measurement gaps that occurred in the velocity distribution. In this approach, the measurement results with similar discharge conditions in the entire time series, i.e. PTV results for the same water levels, are statistically analysed, filtered and summarised in a lookup table. The gaps in the measurements due to missing particles are filled with the data from the lookup table.

For the data collection, three camera gauges were installed at regular gauging stations of the Saxon State Agency for Environmental and Agricultural Monitoring (BfUL). The camera gauges recorded short video sequences at regular time intervals, which were used to determine the velocity distributions using the FlowVelo tool (Eltner et al., 2020). This resulted in three time series covering a period of 10-15 months. For the validation of the optical discharge time series, the regular water level and discharge measurements of the BfUL are used. 

The application of "OptiQ" shows a significant adjustment of the optically determined discharge data to the reference measurement at all three gauging stations. While acceptable results were determined with the arithmetic mean only at higher discharge, the results with the velocity area method and the moving average are similarly good at all discharges. At the gauging station in Elbersdorf, the average difference from the reference value could be reduced from 29% to 15% with "OptiQ". In the next step, it is planned to further develop the statistical model "OptiQ" by using Deep Learning.

How to cite: Kutscher, A., Grundmann, J., Eltner, A., Blanch, X., and Hedel, R.: Application of optical Particle Tracking Velocimetry (PTV) to determine continuous discharge time series, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-9946, https://doi.org/10.5194/egusphere-egu23-9946, 2023.

In November 2021, an atmospheric river swept the Pacific Northwest region, causing one of the costliest natural disasters in Canadian history. Among others, the Coldwater River in Merritt, British Columbia caused widespread flooding on November 15th, 2021, resulting in extensive damage to the infrastructure and total evacuation of the residents.

Estimating the magnitude of this flood is difficult, as it damaged the local flow monitoring station and altered the surrounding landscape. However, parts of this flooding event, including the flow close to its peak, were filmed by local residents using mobile devices or drones. Though with significant perspective distortion and imprecision, they still provide valuable information on the extreme flow event, which would have otherwise been lost or neglected. The objective of this study is to apply image velocimetry techniques to these videos, with limited resources and geodata, for reconstructing surface velocities and discharges during the flood.

The analysis method consists of using LSPIV and Farneback optical flow on the original clips where possible. Objects are identified in the videos, then geolocated or surveyed after the flood, for rectification of raw velocities. This allows multiple iterations, accounting for uncertainties in the rectification parameters. Discharges are then calculated using surveyed or reconstructed transects, and water surface elevations estimated from the video frames.

Preliminary results of both methods will be presented and compared on the use of lens distortion correction, different contrast enhancement block sizes, and interrogation area or filter sizes. Validations of the calculated discharges against flow observations from the Water Survey of Canada will also be included.

How to cite: Yang, J. J. S. and Weijs, S. V.: Use of image velocimetry techniques on citizen videos of the November 2021 flooding event flows in Merritt, British Columbia, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-10094, https://doi.org/10.5194/egusphere-egu23-10094, 2023.

EGU23-10348 | Orals | HS1.2.2

Reproducibility and uncertainty for national Canadian hydrometric stations 

Shervan Gharari, Hongli Liu, Jim Freer, Paul Whitfield, Tricia Stadnyk, Alain Pietroniro, and Martyn Clark

Reliable and accurate river streamflow or discharge measurement and reporting are essential for engineering, economic, and social decision-making. Discharge values are often perceived as true and deterministic by users, modelers, and decision-makers. In this study, the processes of discharge estimation by the Water Survey of Canada, WSC, are presented. The process of inferring the discharge (water volume over time) based on stage (water level) through stage-discharge relationships or “rating curves” including related terminologies is described. Multiple practices of rating curve construction and discharge estimation across WSC hydrometric stations are explored. Major processes of "override" and "temporary shift" which significantly affect the discharge estimation are elaborated. The reproducibility of the published discharge data using data from the production process for approximately 1750 active hydrometric stations operated by WSC is examined. Other impacts of temporary shift and override have been evaluated on the properties such as discharge residuals or performance metrics. Recommendations are made for wider access to metadata and measurements that are essential to quantify the reproducibility and uncertainty of reported discharge values. Open science, particularly Earth system modeling, demands clear communication of reproducibility, and uncertainty of published discharge.

How to cite: Gharari, S., Liu, H., Freer, J., Whitfield, P., Stadnyk, T., Pietroniro, A., and Clark, M.: Reproducibility and uncertainty for national Canadian hydrometric stations, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-10348, https://doi.org/10.5194/egusphere-egu23-10348, 2023.

EGU23-11248 | ECS | Orals | HS1.2.2

Hydrodynamic modelling to assess habitat suitability of the Ganga River 

Gaurav Kailash Sonkar and Kumar Gaurav

We perform hydrodynamic modelling using a 2D HEC-RAS model to assess the hydraulic habitat suitability in a data-constrained reach (7 km) of the Ganga River. This reach of the Ganga River is located within two structural barriers of the upper Ganga plain, namely the Bijnor barrage in upstream and the Narora barrage in downstream. It is an active river dolphin and gharial habitat. To setup and run the 2D flow simulation in HEC-RAS, we used topographic data from a LiDAR drone survey, channel bathymetry from field campaigns, time-series river stage (to define the boundary conditions of the model domain), and water surface slope from using the real-time kinematic GPS. We use water level time series data from a satellite altimeter (downstream) and discharge measured in the field using an ADCP for model calibration and validation, respectively.

We found that the study reach has poor habitat suitability at low flow, which improves at median flow. The use of altimeter datasets for model calibration is quite handy when the in-situ data is not readily available. This study provides a methodological framework to assess the hydraulic habitat suitability in rivers near structural interventions.

How to cite: Sonkar, G. K. and Gaurav, K.: Hydrodynamic modelling to assess habitat suitability of the Ganga River, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-11248, https://doi.org/10.5194/egusphere-egu23-11248, 2023.

EGU23-12058 | Orals | HS1.2.2 | Highlight

Rapid streamflow monitoring with drones 

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

Accurate and reliable streamflow monitoring data are urgently needed for many new locations to tackle the on-going climate emergency, where we now see increasingly severe impacts on society from extreme flows. Yet, traditional river monitoring methods depend on empirical rating-curve methods for which it typically takes many years or decades to obtain reliable data, in particular for extreme flows. This gap between increasing needs and current monitoring capabilities calls for new methods to be developed.

Drones provide an unprecedented ability to measure both the physical and hydraulic characteristics of a river in an efficient manner. Topography, water surface slope, surface water velocity and even bathymetry can be derived from drone images and drone lidar data. We exploited this potential by incorporating drone data into the framework for Rating curve Uncertainty estimation using Hydraulic Modelling (RUHM). The RUHM framework combines a one-dimensional hydraulic model with Bayesian inference and together with drone data it allows us to efficiently estimate a reliable rating curve and its associated uncertainty based on as few as three gaugings.

We present our results from applying RUHM to Swedish gauging stations where we model rating curves and streamflow based on drone data. We primarily used low-cost camera drones to collect both the input (DEM, vegetation, bathymetry) and calibration data (water surface slope, surface velocity) for the hydraulic model, but also tested the capabilities of drone lidar data. Our aim was to estimate reliable rating curves with RUHM based only on data from the drone flights. We assessed the uncertainty in the drone-derived model input and calibration data compared to traditional fieldwork techniques, as well as their impact on the RUHM-modelled rating curves and streamflow results.

We find that careful planning of when to fly the drone is important for obtaining good-quality model input and calibration data. Using a combination of drone camera and drone lidar data we were able to obtain all the data needed for RUHM from the drone flights. Extreme low and high flows were reliably modelled with RUHM with constrained uncertainty based on as few as three low and middle flow gaugings, without the need for gauging extreme flows. We conclude that using RUHM with drone data is an efficient and promising alternative to traditional streamflow monitoring methods, being much less time-consuming and costly, as well as involving fewer risks to field staff.

How to cite: Westerberg, I., Mansanarez, V., Lyon, S., and Lam, N.: Rapid streamflow monitoring with drones, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-12058, https://doi.org/10.5194/egusphere-egu23-12058, 2023.

EGU23-13332 | Orals | HS1.2.2

Measuring bedload motion time at sub-second scale using Benford's law from long-term acoustic recordings 

Ci-Jian Yang, Jens.M Turowski, Qi Zhou, Hui Tang, Ron Nativ, and Wen-Sheng Chen

Bedload transport is a natural process that strongly affects the Earth’s surface system. An important component of quantifying bedload transport and establishing early warning systems is obtaining the parameters at the onset of bedload motion. Bedload transport can be monitored with passive acoustic methods, e.g., hydrophones. Yet, an efficient method for identifying the onset of bedload transport from long-term continuous acoustic data is still lacking. Benford’s Law defines the specific frequency distribution of the first digits of datasets that have been used to distinguish stochastic from chaotic processes in nature when this process causes higher energy events than baseline. Here, we apply Benford’s law to continuous acoustic recordings from Baiyang hydrometric station, a tributary of Liwu River, Taiwan at the frequency of 32 kHz from stationary hydrophones deployed for three years since 2019. We construct a workflow to parse sound combinations of bedload transportation and analyze them in the context of hydrometric sensing constraining the onset, and recession of bedload transportation. We identify two bedload transportation events that lasted 17 and 45 hours, respectively, covering about 0.35% of the time per year. Our workflow allows filtering 99% of background signal and focuses on two events including bedload motions. Given that fluvial seismology has successfully monitored fluvial processes, continuous monitoring in three directions (N-S, W-E, vertical) brings board discussion orientations, e.g., the direction of source or migration of mass movement. Therefore, we suggest that the application of Benford’s law on seismic data of Earth's surface processes has great potential.

How to cite: Yang, C.-J., Turowski, J. M., Zhou, Q., Tang, H., Nativ, R., and Chen, W.-S.: Measuring bedload motion time at sub-second scale using Benford's law from long-term acoustic recordings, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-13332, https://doi.org/10.5194/egusphere-egu23-13332, 2023.

EGU23-14020 | ECS | Orals | HS1.2.2

Adaptive real-time forecasting using model-driven monitoring of catchment inflows and water supply reservoir dynamics 

Nicholas Hutley, Nathaniel Deering, Daniel Wagenaar, Ryan Beecroft, Josh Soutar, Alistair Grinham, Badin Gibbes, and Simon Albert

Real-time monitoring networks are increasingly prevalent in supporting the management of environmental systems as the technology for live data collection becomes more accessible. Additionally, ecosystem and water resource pressures have persisted and intensified under climate pressures and an expanding anthropogenic footprint. The way in which models and data are fused in the day-to-day management of water resources operations, as well as for long-term planning and investment, has been a critical field of research. An adaptive real-time monitoring-integrated learning modelling approach was developed and applied to improve the understanding of the mixing dynamics in a water supply reservoir in Queensland, Australia. This was accomplished through the combination of sequentially linked catchment and reservoir models with in situ real-time measurements of temperature and flow along with meteorological forecasts from an Australian numerical weather model, to produce short-term water quality forecasts. An adaptive learning catchment model was developed and linked for each inflow arm of the reservoir using the Australian Water Balance Model. This framework enabled automated online communication to researchers and managers around the current performance of the inflow predictions and the confidence expected in the current forecasts. Moreover, this live learning catchment model was coupled with a real-time adaptive three-dimensional hydrodynamic model of the reservoir iteratively training using data from the deployed real-time temperature monitoring system. A prototype internet-connected remotely operable autonomous surface vessel was deployed with a winching system for conducting dynamic water quality profiling operations under the guidance of waypoints guidance generated from the real-time adaptive modelling forecasts. Data collected by ASV was subsequently provided back to the modelling system in real-time. The complete system facilitated the online adaptive forecasting of mixing dynamics in the reservoir and the automated identification of features of interest for water quality profiling, as well as dynamically monitoring the areas potentially most valuable for model learning development to improve system-wide understanding and forecast certainty through addition into the live dataset for ongoing training and evaluation. Evidence was found in support of a rolling iterative calibration procedure for increasing model skill sensitivity to different processes occurring over temporal and spatial scales across both catchment and receiving water models. Dynamically guided spatial monitoring generated from maximum predicted areas of variation and parameter sensitivity in the real-time adaptive receiving water model demonstrated that monitoring of the receiving water inflow arms during inflow events was necessary during inflow events to train the model on the strongest signal of the driving force of changes in the receiving water environment. Overall, the uncertainty in rainfall events from both forecasted and observed sources cascading with the uncertainty in catchment simulations with only static indirect monitoring of flow (ungauged at any of the inflow arms to the reservoir) was found to be the most significant hindrance to the utility of the applied real-time adaptive modelling framework. The application of an adaptive computer vision-based stream gauging approach was then trialled on one of the ungauged inflow arms in order to supplement this gap.

How to cite: Hutley, N., Deering, N., Wagenaar, D., Beecroft, R., Soutar, J., Grinham, A., Gibbes, B., and Albert, S.: Adaptive real-time forecasting using model-driven monitoring of catchment inflows and water supply reservoir dynamics, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-14020, https://doi.org/10.5194/egusphere-egu23-14020, 2023.

EGU23-14234 | Posters on site | HS1.2.2

Sources of uncertainty in video-based flow observations, revealed by co-location experiment 

Hessel Winsemius, Salvador Peña-Haro, Frank Annor, Rick Hagenaars, Wim Luxemburg, Gijs Van den Munckhof, Felix Grimmeisen, and Nick Van de Giesen

In the last years, several methods to establish surface flow velocities and river flow from camera videos have been developed and codified into software. Together with a hardware setup, these may be used to establish near real-time observations of river flow. The hardware setup used and associated quality of the camera, methods to pre-process, process and post-process the videos may all result in errors, and uncertainties. In this contribution we assess what the main sources of uncertainty are, and under what conditions these may appear, focusing on both hardware and processing methods. We do this by co-locating two different camera setups, and using two different software processing methods. For camera setups we use a very simple and low cost FOSCAM FI9900EP running at its maximum of 4Mbps and a much better quality Vivotek IB9367-EHT running at 20Mbps. As systems we use the DischargeKeeper and pyOpenRiverCam.

The cameras were co-located over a significantly long period at a site in Limburg in The Netherlands, and footage analyzed with 15-minute intervals. Videos were treated with as much as possible the same settings, reprojection resolution and window. Results were compared in terms of the ability to resolve velocities (amount and quality) and the impact of post-processing. Integrated flow over a cross-section is also compared. We assess under what conditions flow and velocity estimates are robust and similar and under what conditions these diverge focusing on the platform used, light conditions, and flow conditions.

Keywords: River flow monitoring, stage-discharge relationships, OpenRiverCam, DischargeKeeper, computer vision

The work leading to these results has received funding from the German Federal Ministry of Education and Research (BMBF) and the CLIENT II program (Drought-ADAPT, FKZ: 01LZ2002B) and the European Horizon Europe Programme (2021-2027) under grant agreement no. 101086209 (TEMBO Africa). The opinions expressed in the document are of the authors only and no way reflect the European Commission’s opinions. The European Union is not liable for any use that may be made of the information.

How to cite: Winsemius, H., Peña-Haro, S., Annor, F., Hagenaars, R., Luxemburg, W., Van den Munckhof, G., Grimmeisen, F., and Van de Giesen, N.: Sources of uncertainty in video-based flow observations, revealed by co-location experiment, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-14234, https://doi.org/10.5194/egusphere-egu23-14234, 2023.

EGU23-14752 | Posters on site | HS1.2.2

Machine learning for water detection in ephemeral streams 

Salvador Peña-Haro, Daniel Hernandez, and José M. Cecilia

Measuring the volumetric water flow in ephemeral streams, typical of semi-arid climates, in which water rarely flows, is challenging since water only flows some days per year and some times it is in the form of flash floods. In this type of conditions it is important to detect when there is water in the stream. For this, we have implemented a machine learning algorithm for water detection and for stream gauge measurement.

Machine learning was used to differentiate pixels of the image that contains water from those those that do not via image segmentation. Different segmentation models have been proposed, but in our case we used an encoder-decoder DNN architecture based on DeepLabV3. To train the model, we used the ArtificiaL And Natural waTer-bodIes dataSet (ATLANTIS) data-set. However not all the images were used since these data-set includes classes that are not representative for our application, hence the total number of images used for training was 685. Additionally the original defined classes were merged to reduce the problem to a semantic binary segmentation problem, since our objective is to simply detect the presence of water on the stream. In addition to those images, we have used other images recorded by fix cameras looking at some ephemeral streams to improve the training.

The trained network was used to analyze 50 images with different water levels or no water. To evaluate its performance and indicator was defined which considered the number of pixels classified as water inside the image area covered by the stream over the total number of potential pixels having water, and a 60% threshold was used to determine if there is water in the stream. From the 50 images analyzed, only 3 were wrongly classified giving promising results.

This work has been supported by the European Union’s Horizon 2020 research and innovation programme under grant agreement No 101017861 and also by projects RTC2019-007159-5 and Ramon y Cajal Grant RYC2018-025580-I, funded by MCIN/AEI/10.13039/501100011033, “FSE invest in your future” and “ERDF A way of making Europe”

How to cite: Peña-Haro, S., Hernandez, D., and Cecilia, J. M.: Machine learning for water detection in ephemeral streams, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-14752, https://doi.org/10.5194/egusphere-egu23-14752, 2023.

EGU23-16552 | Orals | HS1.2.2 | Highlight

Quantitative and Qualitative River Monitoring Using an Innovative UAV-USV Tandem System 

Issa Hansen, Salvador Peña-Haro, Beat Lüthi, Frank-Andreas Weber, Juan Ramirez, Benjamin Eberhardt, Thomas Gattung, Julian Teege, Enrico Neumann, Ralf Becker, and Jörg Blankenbach

The use of modern digital technologies in water management is an important driver for obtaining better data for assessing the status of water bodies and their development. These data can be beneficially implemented for the monitoring and management of rivers and especially waterways.

In the BMDV-funded project RiverCloud, an autonomous tandem system consisting of an Unmanned Aerial Vehicle (UAV) and an Unmanned Surface Vehicle (USV) is being developed under the coordination of the gia of RWTH Aachen University, which will provide spatially and temporally high-resolution data for the development and maintenance of waterways as well as for river management. The contribution introduces the developed coupled UAV/USV tandem system with its mounted sensors for high resolution data acquisition and continuously accurate georeferencing and presents some significant results using the example of a study area on the Rhine River (Tomateninsel).

The data presented are, among others, camera-based flow measurements using an image processing method, discharge data of a precise ADCP (Acoustic Doppler Current Profiler) with 2000 kHz frequency and ten water quality parameters using a multi-parameter probe. All data mentioned were simultaneously collected in two locations of the study area on the Rhine River in September 2022. The 4 seconds videos collected by the UAV-camera were processed using an image processing method based on the surface velocity after implementing a new developed stabilisation tool. The cross-section data collected by ADCP were used for the configuration of the two sites. The agreement between ADCP and camera-based flow and discharge data was very good on both sites with less than 5% deviation for a discharge value of approx. 600 m3/s and 1.63 m/s mean velocity. The water quality parameters collected during the measuring campaign were temperature, conductivity, salinity, pH value, oxygen concentration, oxygen saturation, ammonium, turbidity, Total suspended solids (TSS) and total dissolved solids (TDS). The water quality data were in the expected ranges for river water (e.g. average values: pH 7.8, T 21.8°C, EC 0.35 mS/cm, Sal 0.71%, O2 7.5 mg/l, NH4+ 0.3 mg/l).

The results, specific requirements of the developed solution and challenges under the measuring conditions of the study area are presented in this paper. The data collected are used as the input of an overview report for river or waterway water flow and quality monitoring.

How to cite: Hansen, I., Peña-Haro, S., Lüthi, B., Weber, F.-A., Ramirez, J., Eberhardt, B., Gattung, T., Teege, J., Neumann, E., Becker, R., and Blankenbach, J.: Quantitative and Qualitative River Monitoring Using an Innovative UAV-USV Tandem System, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-16552, https://doi.org/10.5194/egusphere-egu23-16552, 2023.

In recent years the changing climate has resulted in an increased prevalence of extreme weather, with corresponding extreme precipitation and surface flow events. Adapting management of water and other natural resources to these conditions requires accurate and robust tools to measure water flow, and in particular the development of non-contact measurement methods.

Once such method is Infrared quantitative image velocimetry (IR-QIV), which is a large scale surface velocimetry method that uses infrared imagery to calculate the mean and instantaneous velocity at high resolution in space and time, over large spatial areas (Schweitzer & Cowen, WRR 2021). IR-QIV can operate continuously for extended periods (days, weeks, etc.) without requiring artificial illumination or particle seeding of the flow. The high resolution, continuous, measurement capabilities of IR-QIV make it particularly well suited to applications where the spatial and temporal variance of the flow must be resolved, such as fishery management, air-water heat and gas exchange, and flow-structure interaction studies.

We present metrics of turbulence, estimates of gas transfer rates, and other hydrodynamic properties calculated from velocity measurements conducted by IR-QIV at the surface of several rivers in California, and Michigan, USA. The measurements were made as part of fishery management projects, motivated by efforts to better understand and manage the interaction of migrating fish and the hydrodynamic environment. Results are validated by comparison with acoustic velocity measurements. 

How to cite: Schweitzer, S. and Cowen, E. A.: Turbulence metrics at the surface of rivers, measured by Infrared Quantitative Image Velocimetry (IR-QIV), EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-16919, https://doi.org/10.5194/egusphere-egu23-16919, 2023.

EGU23-17240 | ECS | Posters on site | HS1.2.2

Generating risk maps for river migration using probabilistic modeling 

Omar Wani, Brayden Noh, Kieran Dunne, and Michael Lamb

Human settlements and infrastructure in alluvial floodplains face erosional risk due to the lateral migration of meandering rivers. There is a large body of scientific literature on the dominant mechanisms driving river migration. However, it is challenging to make accurate forecasts of river meander evolution over multiple years. This is in part because deterministic mathematical models are not equipped to account for stochasticity in the system. Besides, uncertainty due to model deficits and unknown parameter values remains. For a more reliable assessment of risks, we therefore need probabilistic forecasts. In this work, we suggest a workflow to generate river-migration risk maps using probabilistic modeling. Forecasts for river channel position over time are generated by Monte Carlo runs, using a distribution of model parameter values inferred from satellite data, enabling us to make risk maps for river migration. We demonstrate that such risk maps are more informative in avoiding false negatives, which can be both detrimental and costly, in the context of assessing erosional hazards due to river migration. 

How to cite: Wani, O., Noh, B., Dunne, K., and Lamb, M.: Generating risk maps for river migration using probabilistic modeling, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-17240, https://doi.org/10.5194/egusphere-egu23-17240, 2023.

HS1.3 – Cross-cutting hydrological sessions

EGU23-556 | ECS | Orals | HS1.3.1

A Modeller’s Compass: How Modellers Navigate Dozens of Decisions 

Janneke Remmers, Rozemarijn ter Horst, Ryan Teuling, and Lieke Melsen

The usage of hydrological models is diverse and omnipresent. For practical purposes, these models are applied to, for example, flood forecasting, water allocation, and climate change impacts. Numerous methods exist to execute any modelling study. Choosing a method creates a narrative behind each model result. This implies that models are not neutral. So, how do modellers make these decisions? We conducted fourteen semi-structured interviews between September and December 2021 with nine modellers from six different water authorities and five modellers from four different consultancy companies in the Netherlands. The interviews were all recorded and transcribed. We executed an inductive content analysis on the transcriptions. We will discuss the motivation modellers have to make choices during the modelling process. With these insights, we aim to contribute to a discussion on how models, despite their unavoidable non-neutrality, can be robust and dependable to support decision making. Standardisation, e.g. automation, can be a way to achieve this. Understanding the social aspects behind the modelling process is necessary to move forward in modelling and modelling workflows, as well as being able to share and reflect on the model results including the narrative behind it.

How to cite: Remmers, J., ter Horst, R., Teuling, R., and Melsen, L.: A Modeller’s Compass: How Modellers Navigate Dozens of Decisions, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-556, https://doi.org/10.5194/egusphere-egu23-556, 2023.

Most systematic bias correction approaches which are developed based on the bias of the statistical properties of interest perform well to bias correct the current climate simulations with respect to observations. However, the significance of the application of systematic bias correction approaches on the raw output of climate model simulations remains a debate due to the unavailability of future climate observation to validate the approach.

The output of a recent ultra-high resolution climate model simulation, UHR-CESM, demonstrates the best performance to simulate variability of sea surface temperature (SST) in the tropical Pacific with an exception of a small bias in mean. This knowledge encouraged us to use the outputs of the model to represent the truth both in current and future climates. We use the output of the model in response to the current climate CO2 concentration as the representative of the current climate. While the outputs of model simulation in response to doubling and quadrupling CO2 concentrations are used as the representative of the truth of future climates.

We bias correct monthly SST simulations for 8 (eight) Coupled Model Intercomparison Project 6 (CMIP6) over the Niño 3.4 region having the same CO2 concentration as our reference model using a novel time-frequency continuous wavelet-based bias correction (CWBC). The results show a nearly perfect correction of distributional, trend, and spectral attributes biases in the 8 (eight) climate model simulations in the current climate and a consistent reduction of the biases in the model simulation in response to doubled CO2 concentration. Although the overall quality of the statistical attributes is improved after the application of bias correction in response to the more extreme change of quadrupled CO2 concentration, a degradation in the spectral attributes is observed. It shows that a systematic bias correction approach has its upper limit. Therefore, while the application of bias correction approaches is recommended prior to the further use of raw climate model simulations, up to what extent future climate simulations are reliably bias corrected should be handled carefully.

How to cite: Kusumastuti, C., Mehrotra, R., and Sharma, A.: Is there an upper extent to systematic bias correction of climate model simulations? Application to low-frequency variability within the Niño3.4 region, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-579, https://doi.org/10.5194/egusphere-egu23-579, 2023.

Hydrological models play a key role in contemporary hydrological scientific research. For this study, 400+ scientific hydrological vacancies were analyzed, to evaluate whether the job description already prescribed which model must be used, and whether experience with a specific model was an asset. Of the analysed job positions, 76%  involved at least some modelling. Of the PhD positions that involved any modelling, the model is already prescribed in the vacancy text in 17%  of the cases, for postdoc positions this was 30%. A small questionnaire revealed that also beyond the vacancies where the model is already prescribed, in many Early-Career Scientist (ECS) projects the model to be used is pre-determined and, actually, also often used without further discussion. There are valid reasons to pre-determine the model in these projects, but at the same time, this can have long-term consequences for the ECS: experience with the model will influence the research identity the ECS is developing, and might influence future opportunities of the ECS - it might be strategic to gain experience with popular, broadly used models, or to become part of an efficient modelling team. This serves an instrumental vision on modelling. Seeing models as hypotheses calls for a more critical evaluation. We can educate ECS the current rules of the game, while at the same time actively stimulate critically questioning these rules.

How to cite: Melsen, L.: Recruitment of early career scientists for hydrological modelling positions: implications for model progress, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-904, https://doi.org/10.5194/egusphere-egu23-904, 2023.

EGU23-968 | Posters on site | HS1.3.1

The Great Lakes Runoff Intercomparison Project (GRIP-GL) 

Juliane Mai, Hongren Shen, Bryan Tolson, Étienne Gaborit, Richard Arsenault, James Craig, Vincent Fortin, Lauren Fry, Martin Gauch, Daniel Klotz, Frederik Kratzert, Nicole O'Brien, Daniel Princz, Sinan Rasiya Koya, Tirthankar Roy, Frank Seglenieks, Narayan Shretha, Andre Guy Temgoua, Vincent Vionnet, and Jonathan Waddell

Model intercomparison studies are carried out to test and compare the simulated outputs of various model setups over the same study domain. The Great Lakes region is such a domain of high public interest as it not only resembles a challenging region to model with its trans-boundary location, strong lake effects, and regions of strong human impact but is also one of the most densely populated areas in the United States and Canada. This study brought together a wide range of researchers setting up their models of choice in a highly standardized experimental setup using the same geophysical datasets, forcings, common routing product, and locations of performance evaluation across the 1x106 km2 study domain. The study comprises 13 models covering a wide range of model types from Machine Learning based, basin-wise, subbasin-based, and gridded models that are either locally or globally calibrated or calibrated for one of each of six predefined regions of the watershed. This study not only compares models regarding their capability to simulated streamflow (Q) but also evaluates the quality of simulated actual evapotranspiration (AET), surface soil moisture (SSM), and snow water equivalent (SWE).

The main results of this study are:

  • The comparison of models regarding streamflow reveals the superior quality of the Machine Learning based model in all experiments performed.
  • While the locally calibrated models lead to good performance in calibration and temporal, they lose performance when they are transferred to locations the model has not been calibrated on.
  • The regionally calibrated models exhibit low performances in highly regulated and urban areas as well as agricultural regions in the US.
  • Comparisons of additional model outputs against gridded reference datasets show that aggregating model outputs and the reference dataset to basin scale can lead to different conclusions than a comparison at the native grid scale.
  • A multi-objective-based analysis of the model performances across all variables reveals overall excellent performing locally calibrated models as well as regionally calibrated models.
  • Model outputs and observations produced and used in this study are available on an interactive website (www.hydrohub.org/mips_introduction.html#grip-gl) and on FRDR (http://www.frdr-dfdr.ca).

How to cite: Mai, J., Shen, H., Tolson, B., Gaborit, É., Arsenault, R., Craig, J., Fortin, V., Fry, L., Gauch, M., Klotz, D., Kratzert, F., O'Brien, N., Princz, D., Rasiya Koya, S., Roy, T., Seglenieks, F., Shretha, N., Temgoua, A. G., Vionnet, V., and Waddell, J.: The Great Lakes Runoff Intercomparison Project (GRIP-GL), EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-968, https://doi.org/10.5194/egusphere-egu23-968, 2023.

EGU23-2008 | Orals | HS1.3.1

More Complex is Not Necessarily Better in Large-Scale Hydrological Modeling 

Ralf Merz, Arianna Miniussi, Stefano Basso, and Larisa Tarasova

Conceptual hydrological models are irreplaceable tools for large-scale (i.e., from regional to global) hydrological predictions. Large-scale modeling studies typically strive to employ one single model structure regardless of the diversity of catchments under study. However, little is known on the optimal model complexity for large-scale applications. In a modeling experiment across 700 catchments in the contiguous United States, we analyze the performance of a conceptual (bucket style) distributed hydrological model with varying complexity (5 model versions with 11–45 parameters) but with exactly the same inputs and spatial and temporal resolution and implementing the same regional parameterization approach. The performance of all model versions compares well with those of contemporary large-scale models tested in the United States, suggesting that the applied model structures reasonably account for the dominant hydrological processes. Remarkably, our results favor a simpler model structure where the main hydrological processes of runoff generation and routing through soil, groundwater, and the river network are conceptualized in distinct but parsimonious ways. As long as only observed runoff is used for model validation, including additional soil layers in the model structure to better represent vertical soil heterogeneity seems not to improve model performance. More complex models tend to have lower model performance and may result in rather large uncertainties in simulating states and fluxes (soil moisture and groundwater recharge) in model ensemble applications. Overall, our results indicate that simpler model structures tend to be a more reliable choice, given the limited validation data available at large scale.

How to cite: Merz, R., Miniussi, A., Basso, S., and Tarasova, L.: More Complex is Not Necessarily Better in Large-Scale Hydrological Modeling, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-2008, https://doi.org/10.5194/egusphere-egu23-2008, 2023.

EGU23-5702 | Posters on site | HS1.3.1

The eWaterCycle platform for open and FAIR hydrological collaboration 

Rolf Hut, Jerom Aerts, Pau Wiersma, Vincent Hoogelander, Nick van de Giesen, Niels Drost, Peter Kalverla, Ben van Werkhoven, Stefan Verhoeven, Fakhereh (Sarah) Alidoost, Barbara Vreede, and Yang Liu

The eWaterCycle platform introduced in 2022 (https://doi.org/10.5194/gmd-15-5371-2022) provides hydrologists with an online platform to conduct numerical studies involving hydrological models. It allows hydrologists to work with each other's data and datasets directly from a webbrowser. The workflow of the experiment done is clearly visible, reproducible and easily adaptable because of how eWaterCycle separates the model (the algorithm) used from the experiment done with the model. eWaterCycle is designed such that research conducted on the platform is ‘FAIR by design’. Using eWaterCycle, studies can be done in less time, more transparently and by more junior members of the hydrological community than was possible a few years ago. 

In this presentation, we will explain the capabilities of the eWaterCycle platform and show them by describing recently (published) works of MSc and PhD members of our team, including a model coupling study, a large sample hydrology study and a climate impact assessment study.

How to cite: Hut, R., Aerts, J., Wiersma, P., Hoogelander, V., van de Giesen, N., Drost, N., Kalverla, P., van Werkhoven, B., Verhoeven, S., Alidoost, F. (., Vreede, B., and Liu, Y.: The eWaterCycle platform for open and FAIR hydrological collaboration, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-5702, https://doi.org/10.5194/egusphere-egu23-5702, 2023.

EGU23-7800 | Orals | HS1.3.1

What motivates model developments? A multi-perspective case study from snow physics models. 

Cécile Ménard, Sirpa Rasmus, and Ioanna Merkouriadi

Historically, snow physics models were developed to forecast avalanches. Over the years, their application has broadened to hydrological, climatological, ecological and permafrost studies to cite but a few. However, the structure of mid-latitude mountain snowpacks upon which snow physics models are based (generally deep snowpack with snow denser at the bottom than at the top because of compaction) differs considerably from the structure of high latitude snowpacks (generally shallow snowpack with dense wind-compacted snow at the top and large snow crystals at the bottom). This difference has been known for decades to be a potentially large source of uncertainty when simulating heat exchanges in the Arctic and Antarctic. Therefore, with Arctic warming having consequences on the global climate, why have snow physics modellers not developed a model with a high latitude or “arctic snowpack” yet? Taking this question as a case-study to understand the role that subjective decisions play at every phase of model developments, we interviewed more than twenty snow physics model users (e.g. ecologists, anthropologists, remote sensing and climate scientists) and developers to understand the following: what motivates model developments? What or who determines which parametrization, which process is to be prioritised over others? What role does the research question play? What about funding or staff availability? We will show that positionality, anchoring bias and interpersonal relationships play far more prominent roles in the physical sciences that commonly acknowledged and will draw lessons from the social sciences to increase transparency in our modelling practice.

How to cite: Ménard, C., Rasmus, S., and Merkouriadi, I.: What motivates model developments? A multi-perspective case study from snow physics models., EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-7800, https://doi.org/10.5194/egusphere-egu23-7800, 2023.

The reliability of rainfall-runoff models in reproducing hydrological drought events is of primary importance for multiple applications (e.g. water resource management or agricultural risk assessment), especially in a context of expected future water scarcity. Typical model performance metrics are often not enough to assess the accuracy in the simulation of droughts. In fact, it is necessary to consider drought-specific indices taking into account, e.g., low flow characteristics, duration and deficit volumes as well as their seasonality and timing. Understanding which hydrological processes are (or are not) adequately modeled and why, in respect to such drought-specific performances, allows to assess the strengths and weaknesses of each model and may provide guidance on how to improve model set-up and its reliability.

Through the application of a conceptual semi-distributed model on a set of Alpine basins, the aim of this preliminary work is to analyse the relationship between drought-specific performance metrics, basin characteristics and model parameters. In particular, the specific influence of the different model state variables (e.g. snow water equivalent, evapotranspiration and soil moisture) on the reproduction of drought events is investigated.

The model used is a semi-distributed modelling framework based on the airGR rainfall-runoff models (Coron et al. 2017), applied through the R package airGRiwr (Dorchies 2022). The case study is a set of Alpine catchments, characterised by a high degree of “nestdness” which allows to fully implement the semi-distributed model structure and to perform its diagnosis.

The major advantage of a semi-distributed model, if properly set-up, is its ability to differentiate hydrological dynamics between the sub-catchments. In mountainous basins, for instance, simulating in a separate way the upstream headwater sub-catchments may substantially improve the accuracy in the simulation of snow storage and melting, which strongly affect the occurrence and timing of drought events. For this reason, the work will also analyse the benefits of an increasing spatial resolution of the semi-distributed set-up of the model, comparing the outcomes obtained when sequentially calibrating the model in a semi-distributed fashion on the upstream sub-catchments in respect to the baseline of a lumped configuration.

 

References

Coron, L., Thirel, G., Delaigue, O., Perrin, C. and Andréassian, V. (2017). The Suite of Lumped GR Hydrological Models in an R package. Environmental Modelling and Software, 94, 166-171, doi: 10.1016/j.envsoft.2017.05.002.

David Dorchies (2022). airGRiwrm: 'airGR' Integrated Water Resource Management. R package version 0.6.1. https://CRAN.R-project.org/package=airGRiwrm

How to cite: Neri, M. and Toth, E.: On the accurate simulation of hydrological droughts in Alpine regions: investigating the multiple role of rainfall-runoff model dynamics and basin characteristics, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-8153, https://doi.org/10.5194/egusphere-egu23-8153, 2023.

EGU23-8553 | ECS | Posters on site | HS1.3.1

Using Docker in environmental research 

Alexander Dolich, Mirko Mälicke, Ashish Manoj J, Jan Wienhöfer, and Erwin Zehe

The virtual research environment V-FOR-WaTer provides functionalities to store and access hydrological and other environmental data from various sources and disciplines. We propose a framework to run containerized tools within the V-FOR-WaTer toolbox, that is intended to solve the problem of combining software or scripts developed in different programming languages.

The framework is used to manage Docker containers, which can contain software like tools for data analysis or environmental modeling. Alongside the well-known advantages of containerization, such as development speed and efficiency, isolation from the local system, dependency management and portability, the usage of containers also ensures a high degree of reproducibility.

Given a scientific context, containers are especially useful to combine scripts in different languages following different development paradigms. To do so, we developed a framework-agnostic container specification which standardizes inputs and outputs from and to containers to ease the development of new tools. As of now we also provide templates for tools developed in Python, R, Octave and NodeJS.

We present an exemplary workflow for the CATFLOW hydrological model. Data from the V-FOR-WaTer environment is loaded using a Python tool and preprocessed with an existing R tool. After running the FORTRAN model, existing tools in Python, R and MATLAB are used for analysis and presentation of results. When executing the workflow, the user does not need to be familiar with the different programming languages of individual tools, since the containerized tools are self-contained by definition.

How to cite: Dolich, A., Mälicke, M., Manoj J, A., Wienhöfer, J., and Zehe, E.: Using Docker in environmental research, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-8553, https://doi.org/10.5194/egusphere-egu23-8553, 2023.

For scientific products to be considered actionable for stakeholder purposes they must meet certain epistemic and contextual conditions of adequacy. In evaluating the adequacy of a scientific product derived from Earth system models for actionable purposes—such as adaptation or resilience planning— there is a tendency to engage in the evaluation of raw model output and subject it to postprocessing to gain desired reliability and fitness. However, this reductive approach and focus on data ignores questions of whether the simulations, model configurations, and representational features of the models are themselves adequate and reliable for the actionable applications. This talk will lay out the reasons why we need to shift our practices to evaluating models and their products in a more holistic manner and provides insight into a framework for doing so. Scientific models—in this case Earth system models—are constructed with certain purposes and research questions in mind. These purposes, and more detailed research questions, engender representational values, which are reflections of what we want to know and why we want to know it. When model development is informed by these representational values underlying our questions and purposes, they are determinants of the decisions made during model construction about what we choose to represent and how we choose to represent it. The consequence is that the models constructed reflect these representational values and occupy a representational perspective, one that is fit for answering the questions and purposes that governed its development, but not those questions and applications that lie outside that perspective. To avoid increasing epistemic risk when using models for actionable purposes, which can result in downstream social harms, we need to assess the adequacy and reliability of our instruments and their products further upstream, in terms of consistency between the representational values that are embedded in the model in virtue of its development pathway and those that are implied in the actionable science questions the model could be applied to answer. More holistic, tailored assessments will allow us to avoid increases in epistemic risk due to how stakeholder representational values and conditions of adequacy can be inconsistent with those values being reflected in the representational content of the model being employed.

How to cite: Morrison, M.: Adequacy and Reliability of Earth System Models: Actionable Purposes, Model Inadequacy and Epistemic Risk, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-8858, https://doi.org/10.5194/egusphere-egu23-8858, 2023.

The COVID-19 pandemic has shown the importance of modeling in guiding decision-making for governments and society, and the significant influence that modelers hold, especially during times of crisis. Water modelers may also encounter similar situations where their models are caught up in political debates, shaping people's everyday lives. 

This paper discusses the cultural and professional norms around water modeling practice that need to be established or revisited in order to make modeling work more responsible, through a review of models developed for COVID-19. It introduces six areas of study for "responsible water modeling" that can advance future theoretical and practical discussions on the topic: (1) building a common appreciation of the concept of responsibility, (2) interactions between science and policy, (3) the influence of boundary judgments on the model's outcome, (4) the politics of uncertainty, (5) stakeholder involvement, and (6) integration and coordination

The paper suggests that by focusing on these subjects, the fundamental principles and characteristics of responsible modeling can be established in order to address and respond to water challenges while also serving the public good.

How to cite: Nabavi, E.: Navigating Responsible Water Modeling in the Wake of COVID-19, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-9710, https://doi.org/10.5194/egusphere-egu23-9710, 2023.

EGU23-10230 | Orals | HS1.3.1

Instrumenting good modelling practice as common practice 

Anthony Jakeman, Sondoss Elsawah, and Serena Hamilton

Good modelling practice has many requirements. Above all, the process should be complete and transparent enough so that the credibility of its conclusions can be comprehended, or even assessed, by its intended audience. And the more complex, uncertain and cross-sectoral the problem being modelled, or potentially devastating its consequences may be, the more the need for good practice. Consequently, good modelling practice is essential in addressing not just climate change issues, but also cross-sectoral issues such as occurs with water, energy, agriculture and the socio-economy. Yet despite widespread acknowledgment of the grand socio-environmental challenges facing the planet, practices as seen in the major literature largely remain meagre, and most often are pathetically inadequate.

The presentation begins with a list of specific technical complaints around poor practice, ones that could be easily remedied by modellers, to concede this unnecessary state of affairs. We argue for a suitable ontology around concepts for anchoring good modelling practice, including trustworthiness, assurance, robustness, reproducibility and credibility, along with fitness-for-purpose notions of usability, reliability and feasibility. We also emphasize the often-overlooked role of human factors in the modelling process, including assumptions and choices made by the modeller, and consider how consequent biases or uncertainties can be reduced. We then synthesize the steps in the modelling process as recognized in the scientific and grey literature, and provide examples of checklists of questions that merit addressing for each step. Many of these questions prompt consideration of methodological choices, especially around uncertainty and scale. Good modelling practice warrants greater transparency in documenting, justifying and, wherever possible, comparing methodological choices and related assumptions. We argue that the level of robustness to choices be made clearer.

The modelling community must however address how to advance modelling so that good practice becomes not just well-known but common practice. Instruments for achieving this are posited around: regulation by journals in terms of standards that they require for relevant papers published; developing incentives for following good practice; promoting an institutional/community culture around it, and expanding education and capacity building in modelling that focusses from the start on good practice as being fundamental.

How to cite: Jakeman, A., Elsawah, S., and Hamilton, S.: Instrumenting good modelling practice as common practice, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-10230, https://doi.org/10.5194/egusphere-egu23-10230, 2023.

EGU23-10527 | Orals | HS1.3.1

Improving the science and practice of hydrological modelling 

Martyn Clark, Wouter Knoben, Guoqiang Tang, Ashley van Beusekom, Louise Arnal, and Ray Spiteri

Many hydrological modelling groups face similar challenges, with untapped opportunities to share code and concepts across different model development groups. An active community of practice is emerging, where the focus is not so much on developing a community hydrological model, and more on advancing the science and practice of community hydrological modelling. This presentation will summarize our recent efforts to develop open-source models, methods, and datasets to enable process-based hydrological prediction across large geographical domains. This presentation summarizes our recent efforts to advance the science and practice of hydrological modelling, focusing on recent work to (1) develop multi-source probabilistic hydrometeorological forcing datasets on continental and global domains; (2) advance a flexible approach to represent a myriad of physical processes in a unified modelling framework; (3) improve the numerical robustness and efficiency of large-domain terrestrial system model simulations; and (4) develop extensible and reproducible modeling workflows. The presentation will highlight major scientific challenges, future research needs, and some key opportunities for community collaboration.

How to cite: Clark, M., Knoben, W., Tang, G., van Beusekom, A., Arnal, L., and Spiteri, R.: Improving the science and practice of hydrological modelling, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-10527, https://doi.org/10.5194/egusphere-egu23-10527, 2023.

EGU23-11062 | Posters on site | HS1.3.1

A guideline for consistent water quality modeling in rural areas 

Jens Kiesel, Nicola Fohrer, Paul D. Wagner, Marcelo Haas, and Björn Guse

In several hydrological studies the need for consistency in hydrological modeling was highlighted. To achieve model consistency, it is required that all relevant hydrological processes are evaluated for accuracy in their spatio-temporal representation under consideration of available observations. In this study, we transfer the idea of hydrological consistency to water quality modeling. We focus on water quality modelling in rural mesoscale catchments and the interaction with agricultural production systems and their management. Based on several studies, we have developed a guideline which includes the following six challenges:

  • Representation of rural landscape: Spatial and temporal patterns of land use and land management are critical to adequately represent water quality in models. Remote sensing and land use models are very useful resources to be exploited.
  • Accuracy in model structure and model parameters: The transfer of a model diagnostic analysis to water quality leads to a better understanding of how water quality variables are controlled by model structures and corresponding model parameters.
  • Check of multiple model output for consistency: Assessing multiple model outputs regarding their temporal, spatial and process performance using observed time series, remotely sensed spatial patterns, knowledge about transport pathways and even soft data can significantly enhance model consistency.
  • Joint multi-metric calibration of discharge and water quality for all magnitudes: Multi-metric calibration using performance metrics and signature measures both for discharge and water quality, such as flow and nitrate duration curve, leads to more balanced model simulations that represent all magnitudes of discharge and water quality accurately.
  • Scenarios and storylines for reliable land management: Scenarios and storylines should be co-developed with stakeholders in the river basin to increase realism and the acceptance of model results. They should be coherent in space and time, and provide a mix of available management options.
  • Consistent interpretation of impacts on water quality: The interpretation of scenarios can be supported by diagnostic tools to show the effectiveness of measures and their combinations while considering their costs and impacts on ecosystem services.

In our contribution, we give examples and further details regarding each challenge to give insights how to achieve consistency in water quality modelling.

How to cite: Kiesel, J., Fohrer, N., Wagner, P. D., Haas, M., and Guse, B.: A guideline for consistent water quality modeling in rural areas, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-11062, https://doi.org/10.5194/egusphere-egu23-11062, 2023.

EGU23-12261 | ECS | Orals | HS1.3.1

Peeking Inside Hydrologists' Minds: Comparing Human Judgment and Quantitative Metrics of Hydrographs 

Martin Gauch, Frederik Kratzert, Oren Gilon, Hoshin Gupta, Juliane Mai, Grey Nearing, Bryan Tolson, Sepp Hochreiter, and Daniel Klotz

Everyone wants their hydrologic models to be as good as possible. But how do we know if a model is accurate or not? In the spirit of rigorous and reproducible science, the answer should be: we calculate metrics. Yet, as humans, we sometimes follow a scheme of "I know a good model when I see it" and manually inspect hydrographs to assess their quality. This is certainly a valid method for sanity checks, but it is unclear whether these subjective visual ratings agree with metric-based rankings. Moreover, the consistency of such inspections is unclear, as different observers might come to different conclusions about the same hydrographs.

In this presentation, we report a large-scale study where we collected responses from 622 experts, who compared and judged more than 14,000 pairs of hydrographs from 13 different models. Our results show that overall, human ratings broadly agree with quantitative metrics in a clear preference for a Machine Learning model. At the level of individuals, however, there is a large amount of inconsistency between ratings from different participants. Still, in cases where experts agree, we can predict their most likely rating purely from qualitative metrics. This indicates that we can encode intersubjective human preferences with a small set of objective, quantitative metrics. To us, these results make a compelling case for the community to put more trust into existing metrics—for example, by conducting more rigorous benchmarking efforts.

How to cite: Gauch, M., Kratzert, F., Gilon, O., Gupta, H., Mai, J., Nearing, G., Tolson, B., Hochreiter, S., and Klotz, D.: Peeking Inside Hydrologists' Minds: Comparing Human Judgment and Quantitative Metrics of Hydrographs, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-12261, https://doi.org/10.5194/egusphere-egu23-12261, 2023.

EGU23-13770 | Posters on site | HS1.3.1

Towards FAIR hydrological modeling with HydroMT 

Hélène Boisgontier, Dirk Eilander, Laurène Bouaziz, Joost Buitink, Anaïs Couasnon, Roel de Goede, Mark Hegnauer, Tim Leijnse, and Willem van Verseveld

Hydrological models are crucial to understand water systems and perform impact assessment studies. However, these models require a lot of accurate data, especially if the model is spatially distributed. However, sufficiently accurate datasets while available, for example from earth-observations, need to be converted into model-specific, sometimes idiosyncratic, file formats. Therefore, hydrological models require various steps to process raw input data to model data which, if done manually, makes the process time consuming and hard to reproduce. Hence, there is a clear need for automated model instance setup for increased transparency and reproducibility in hydrological modeling.

 

HydroMT (Hydro Model Tools) is an open-source Python package (https://github.com/Deltares/hydromt) that aims to make the process of building hydrological model instances and analyzing their results automated and reproducible. Compared to many other packages for automated model instance setup, HydroMT is data- and model-agnostic, meaning that data sources can easily be interchanged without additional coding and the generic model interface can be used for different model software. This makes it possible to reuse workflows to prepare input from different datasets or for different model software that require the same parameter (e.g. Manning roughness derived from land use maps) and thereby supporting controlled model intercomparison and sensitivity experiments. 

 

In this contribution we show the application of HydroMT for flood hazard modeling using the distributed hydrological Wflow model and the reduced-physics hydrodynamic SFINCS model, both open-source models. We use HydroMT to setup a controlled and reproducible model experiment. We test the sensitivity of both models to various data sources used- and assumptions taken in the model instance building process and compare the skill to simulate peak discharge. Using this application, we discuss the merits and limitations of HydroMT and next steps toward FAIR hydrological modeling.

How to cite: Boisgontier, H., Eilander, D., Bouaziz, L., Buitink, J., Couasnon, A., de Goede, R., Hegnauer, M., Leijnse, T., and van Verseveld, W.: Towards FAIR hydrological modeling with HydroMT, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-13770, https://doi.org/10.5194/egusphere-egu23-13770, 2023.

EGU23-15221 | Orals | HS1.3.1

The persistence of errors: How evaluating models over data partitions relates to a global evaluation 

Daniel Klotz, Martin Gauch, Grey Nearing, Sepp Hochreiter, and Frederik Kratzert

Skillful today, inept tomorrow. Today's hydrological models have pronounced and complex error dynamics (e.g., small, highly correlated errors for low flows and large, random errors for high flows). Modellers generally accept that simple, variance based evaluation criteria — like the Nash-Sutcliffe Efficiency (NSE) — are not fully able to capture these intricacies. The (implied) consequences of this are however seldom discussed.

This contribution examines how evaluating the model over two data partitions (above and below a chosen threshold) relates to a global model evaluation of both partitions combined (i.e., the usual way of computing the NSE). For our experiments we manipulate dummy simulations with gradient descent to approximate specific NSE values for each partition individually. Specifically, we set the NSE for runoff values that fall below the threshold, and vary the NSE of the simulations above the threshold as well as the threshold itself. This enables us to study how the global NSE relates to the partition NSEs and the threshold. Intuitively, one would wish that the global NSE somehow reflects the performance on the partitions in a comprehensible manner. We do however show that this relation is not trivial.

Our results also show that subdividing the data and evaluating over the resulting partitions yields different information regarding model deficiencies than an overall evaluation. The downside is that we have less data to estimate the NSE. In the future we can use this for model selection and diagnostic purposes.

How to cite: Klotz, D., Gauch, M., Nearing, G., Hochreiter, S., and Kratzert, F.: The persistence of errors: How evaluating models over data partitions relates to a global evaluation, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-15221, https://doi.org/10.5194/egusphere-egu23-15221, 2023.

EGU23-15300 | Orals | HS1.3.1

Consistency in Model Performance as a Criterion for Trustworthy Hydrological Modelling 

Andrijana Todorović and Claudia Teutschbein

Various models are available to hydrologists, including models of different structures, spatial and temporal discretisation, or multiple parameter sets of a single model. But the "trustworthiness" of these models is called into doubt when they reproduce runoff equally well in the calibration period (equifinality), but diverge in their simulation outputs outside this period. A common way to account for modelling uncertainty is to use so-called ensembles that combine several model members. However, it has been debated/discussed that models that do not provide “the right answers for the right reasons” and, consequently, yield poor performance in a prediction or forecasting mode, should be omitted from such ensembles. Various evaluation protocols aimed at detecting such models have emerged over the years, however, this remains an open research question, and more research is needed especially in the context of shifting hydrologic regimes in a changing climate.

 

Adopting the consistency in model performance in reproducing runoff as an additional criterion to select among multiple models emerges as a plausible way to identify the most “trustworthy” ones. We propose an approach that relies on detailed analyses of model performance across subperiods of increasing length contained within the calibration period. A good performance in both short and longer subperiods is crucial as the former can be quite extreme (e.g., extremely dry or wet), while the latter “expose” a model to various hydroclimatic conditions. To analyse the consistency in model performance, an efficiency measure (e.g., the Kling-Gupta coefficient, KGE) can be computed in each subperiod, and each model can be ranked in each subperiod according to the measure. Models yielding the most consistent and the highest performance can then be selected either (1) as a certain percentage of models with the highest rank averaged across all subperiods, or (2) by imposing a rank threshold that has to be reached in every subperiod. We here further propose to additionally evaluate the selected subset of consistent and high-performing models over an independent period using various other performance indicators (e.g., Nash-Sutcliffe coefficient or volumetric efficiency) as well as model ability to reproduce hydrological signatures (e.g., mean, high and low flows, or runoff dynamics). The evaluation performance of the selected models can then be compared to the best (reference) model obtained from the calibration over the full calibration period with the selected efficiency measure (here KGE) as the objective function.

 

To showcase the advantages of the proposed approach, it is here applied to two different models (3DNet-Catch and GR4J) each with 20,000 randomly sampled parameter sets in three unimpaired catchments. In addition to the promising results, the proposed approach is characterised by its ease-of-use and flexibility, i.e., it can be implemented with any ensemble of models (e.g., randomly selected parameter sets of a single model, or different models created e.g., from a modular framework), or with any other aspect of model performance.

How to cite: Todorović, A. and Teutschbein, C.: Consistency in Model Performance as a Criterion for Trustworthy Hydrological Modelling, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-15300, https://doi.org/10.5194/egusphere-egu23-15300, 2023.

EGU23-16869 | Posters virtual | HS1.3.1

Open, Quick and Reproducible Hydrological Model Deployment Cloud Platform 

Lele Shu, Yan Chang, Xianhong Meng, Paul Ullrich, Christopher Duffy, Hao Chen, Shihua Lyu, Yaonan Zhang, and Zhaoguo Li

Model and data are essential for current geoscientific research. Too many hydrological models are available for potential modelers, plus too much spatial terrestrial data related to modeling is accessible to users. More importantly, reproducibility is one of the key features in science,  which is barely discussed in hydrological models. Two significant reasons are that (1) the various hydrological models are incompatible since they require different variables, even if some of them share the same terminology, and (2) the complexity of model structure makes it impossible to deploy a model swiftly in any new research area. 
Our project is to establish a Global Hydrological Data Cloud (GHDC, https://shuddata.com) providing essential terrestrial variables for generic hydrological modeling, as modelers provide the watershed boundary and model requests. The data retrieved from the GHDC covers terrain, topology, soil/geology, landuse, hydraulic parameters and meteorological time-series data. The demonstration of three watershed examples with the Simulator of Hydrologic Unstructured Domains (SHUD),  can be a standard paradigm for physically-based hydrological modeling and instructive for other modeling processes, as the procedures are transferable to other hydrological models and regions. 

How to cite: Shu, L., Chang, Y., Meng, X., Ullrich, P., Duffy, C., Chen, H., Lyu, S., Zhang, Y., and Li, Z.: Open, Quick and Reproducible Hydrological Model Deployment Cloud Platform, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-16869, https://doi.org/10.5194/egusphere-egu23-16869, 2023.

EGU23-5 | ECS | PICO | HS1.3.2

Probabilistic analysis of river levees under consideration of time-dependent loads 

Marco Albert Öttl, Jens Bender, and Jürgen Stamm

In the analysis regarding the stability of river dikes, the interactions between the load magnitude of the flood level and the resulting percolation are found to be a highly relevant process. After all, the seepage line separates the cross-sectional area into the water-saturated and the unsaturated crosssectional parts. For homogeneous levees, the position of the seepage line in the stationary case is imprinted in the system by the outer cubature and is well on the safe side for real flood events. In the non-stationary case, the position of the seepage line depends primarily on the changing water level of a flood hydrograph, the resulting water content and suction stresses in the dike, as well as the saturated permeability of the dike construction materials. In the current dimensioning practice according to DIN 19712 and the German DWA-M-507, the characteristic of the hydrograph is not directly applied. So far, for example, the resulting damming duration of a flood hydrograph is only considered indirectly.
This paper presents a methodology, which quantifies natural dependency structures for a selected dike section by synthetically generated dimensioning hydrographs in a probabilistic design. These results are then integrated directly into the geohydraulic process of water penetration. Based on selected water level and discharge time series at a dike section, flood waves can be described in five parameters using the extended flood characteristic simulation according to MUNLV1. After successfully adapting suitable distribution functions, dependencies in the load structure are quantified in the next step using Copula function. Subsequently, any number of synthetic flood hydrographs can be generated by combining these parameters. In keeping with the principle of the Monte Carlo simulation, a sufficiently high number of synthetic events results in extreme conditions with a low probability of occurrence being reliably represented.
Using a developed routine, the process of moisture penetration for the individual flood hydrographs can be simulated and visualized in a transient, geohydraulically numerical model at different points in times. Finally, statements regarding the behavior patterns of the resulting seepage lines, based on the loading situation can be derived and predicted. Based on these results, a reliability analysis then shows the stability of the dike section under the given extreme conditions.

1Ministerium für Umwelt, Landwirtschaft, Natur und Verbraucherschutz des Landes Nordrhein-Westfalen

How to cite: Öttl, M. A., Bender, J., and Stamm, J.: Probabilistic analysis of river levees under consideration of time-dependent loads, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-5, https://doi.org/10.5194/egusphere-egu23-5, 2023.

EGU23-487 | ECS | PICO | HS1.3.2

A physics-informed machine learning approach to estimate surface soil moisture 

Abhilash Singh and Kumar Gaurav

We propose Physics Informed Machine Learning (PIML) algorithms to estimate surface soil moisture from Sentinel-1/2 satellite images based on Artificial Neural Networks (ANN). We have used Improved Integral Equation Model (I2EM) to simulate the radar images backscatter in VV polarisation. In addition, we selected a set of different polarisations, i.e.; (VH, VH/VV, VH-VV), incidence angle, Normalised Difference Vegetation Index (NDVI), and topography as input features to map surface soil moisture. We have used two different approaches to predict soil moisture using PIML. In the first approach, we developed an observation bias in which we selected the difference of backscatter value at each pixel in VV polarisation from satellite and derived from theoretical model derived as one of the input features. Our second approach is based on learning bias, in which we modified the loss function with the help of the I2EM model. Our result shows the learning bias PIML outperforms the observation bias PIML with R = 0.94, RMSE = 0.019 m3/m3, and bias = -0.03. We have also compared the performance with the standalone benchmark algorithms. We observed the learning bias PIML emerged as the most accurate model to estimate the surface soil moisture. The proposed approach is a step forward in estimating accurate surface soil moisture at high spatial resolution from remote sensing images.

How to cite: Singh, A. and Gaurav, K.: A physics-informed machine learning approach to estimate surface soil moisture, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-487, https://doi.org/10.5194/egusphere-egu23-487, 2023.

EGU23-4039 | ECS | PICO | HS1.3.2

UNITE: A toolbox for unified diagnostic evaluation of physics-based, data-driven and hybrid models based on information theory 

Manuel Álvarez Chaves, Anneli Guthke, Uwe Ehret, and Hoshin Gupta

The use of “hybrid” models that combine elements from physics-based and data-driven modelling approaches has grown in popularity and acceptance in recent years, but these models also present a number of challenges that must be addressed in order to ensure their effectiveness and reliability. In this project, we propose a toolbox of methods based on information theory as a step towards a unified framework for the diagnostic evaluation of “hybrid" models. Information theory provides a set of mathematical tools that can be used to study input data, model architecture and predictions, which can be helpful in understanding the performance and limitations of “hybrid” models.

Through a comprehensive case study of rainfall-runoff hydrological modelling, we show how a very simple physics-based model can be coupled in different ways with neural networks to develop “hybrid” models. The proposed toolbox is then applied to these “hybrid” models to extract insights which guide towards model improvement and refinement. Diagnostic scores based on the entropy (H) of individual predictions and the Kullback-Leibler divergence (KLD) between predictions and observations are introduced. Mutual information (I) is also used as a more all-encompassing metric which informs on the aleatory and epistemic uncertainties of a particular model. In order to address the challenge of calculating quantities from information theory on continuous variables (such as streamflow), the toolbox takes advantage of different estimators of differential entropy, namely: binning, kernel density estimation (KDE) and k-nearest neighbors (k-NN).

How to cite: Álvarez Chaves, M., Guthke, A., Ehret, U., and Gupta, H.: UNITE: A toolbox for unified diagnostic evaluation of physics-based, data-driven and hybrid models based on information theory, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-4039, https://doi.org/10.5194/egusphere-egu23-4039, 2023.

We introduce and illustrate our recently developed Augmented Information Physical Systems Intelligence (AIPSI), leveraging and enhancing our proprietary Information Physical Artificial Intelligence (IPAI) and Earth System Dynamical Intelligence (ESDI) to further the mathematically robust, physically consistent and computationally efficient holistic articulation and integration across the latest advances in fundamental physics, geophysical sciences and information technologies.

In theoretical terms, AIPSI brings out a more general principled lingua franca and formal construct to complex system dynamics and analytics beyond traditional hybridisation among stochastic-dynamic, information-theoretic, artificial intelligence and mechanistic techniques.

In practical terms, it empowers improved high-resolution spatiotemporal early detection, robust attribution, high-performance forecasting and decision support across multissectorial theatres of operation pertaining multiple interacting hazards, natural, social and hybrid.

With operational applications in mind, AIPSI methodologically improves the sharp trade-off between speed and accuracy of multi-hazard phenomena sensing, analysis and simulation techniques, along with the quantification and management of the associated uncertainties and predictability with sharper spatio-temporal resolution, robustness and lead.

This is further supported by the advanced Meteoceanics QITES constellation providing coordinated volumetric dynamic sensing and processing of gravitational and electrodynamic fluctuations, thereby providing an instrumentation ecosystem for anticipatory early detection of extreme events such as flash floods, explosive cyclogenesis and imminent disruptive structural critical transitions across built and natural environments.

With the methodological developments at hand, a diverse set of applications to critical theatres of operation are presented, ranging from early detection, advance modelling and decision support to environmental and security agencies entrusted with the protection and nurturing of our society and the environment. Contributing to empowering a more robust early detection, preparedness, response, mitigation and recovery across complex socio-environmental hazards such as those involving massive wildfires, floods and their nonlinear compound interplay, their underlying mechanisms and consequences.

The presentation concludes with an overview of a new large-scale international initiative on multi-hazard risk intelligence networks, where an eclectic diversity of actors ranging from academia and industry to institutions and the civil society come together to co-create emerging pathways for taking this challenging quest even further, in a fundamental coevolution between cutting-edge science, groundbreaking technology and socio-environmental insights to further enrich the ever-learning system dynamic framework at the core of our multi-hazard research and service.

Acknowledgement: This contribution is funded by the Εuropean Union under the Horizon Europe grant 101074004 (C2IMPRESS).

 

How to cite: Perdigão, R. A. P. and Hall, J.: Augmented Information Physical Systems Intelligence (AIPSI) for enhanced spatiotemporal early detection, attribution, prediction and decision support on multi-hazards, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-6617, https://doi.org/10.5194/egusphere-egu23-6617, 2023.

EGU23-8388 | ECS | PICO | HS1.3.2 | Highlight

An ML-based Probabilistic Approach for Irrigation Scheduling 

Shivendra Srivastava, Nishant Kumar, Arindam Malakar, Sruti Das Choudhury, Chittaranjan Ray, and Tirthankar Roy

Globally, agriculture irrigation accounts for 70% of water use and is facing extensive and increasing water constraints. Well-designed irrigation scheduling can help determine the appropriate timing and water requirement for crop development and consequently improve water use efficiency. This research aims to assess the probability of irrigation needed for agricultural operations, considering soil moisture, evaporation, and leaf area index as indicators of crop water requirement. The decision on irrigation scheduling is taken based on a three-step methodology. First, relevant variables for each indicator are identified using a Random Forest regressor, followed by the development of a Long Short-Term Memory (LSTM) model to predict the three indicators. Second, errors in the simulation of each indicator are calculated by comparing the predicted values against the actual values, which are then used to calculate the error weights (normalized) of the three indicators for each month (to capture the seasonal variations). Third, the empirical distribution of each indicator is obtained for each month using the estimated error values, which are then adjusted based on the error weights calculated in the previous step. The probabilities of three threshold values (for each indicator) are considered, which correspond to three levels of irrigation requirement, i.e., low, medium, and high. The proposed approach provides a probabilistic framework for irrigation scheduling, which can significantly benefit farmers and policymakers in more informed decision-making related to irrigation scheduling.

How to cite: Srivastava, S., Kumar, N., Malakar, A., Choudhury, S. D., Ray, C., and Roy, T.: An ML-based Probabilistic Approach for Irrigation Scheduling, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-8388, https://doi.org/10.5194/egusphere-egu23-8388, 2023.

Inference of causality and understanding of extreme events are two intensively developing multidisciplinary areas highly relevant for the Earth sciences. Surprisingly, there is only a limited interaction of the two research areas.

Quantification of causality in terms of improved predictability was proposed by the father of cybernetics N. Wiener [1] and formulated for time series by C.W.J. Granger [2]. The Granger causality evaluates predictability in bivariate autoregressive models. This concept has been generalized for nonlinear systems using methods rooted in information theory [3]. The information theory of Shannon, however, usually ignores two important properties of Earth system dynamics: the evolution on multiple time scales and heavy-tailed probability distributions. While the multiscale character of complex dynamics, such as the air temperature variability, can be studied within the Shannonian framework in combination with the wavelet transform [4], the entropy concepts of Rényi and Tsallis have been proposed to cope with variables with heavy-tailed probability distributions. We will discuss how such non-Shannonian entropy concepts can be applied in inference of causality in systems with heavy-tailed probability distributions and extreme events. Using examples from the climate system, we will focus on causal effects of the North Atlantic Oscillation, blocking events and the Siberian high on winter and spring cold waves in Europe, including the April 2021 frosts endangering French vineyards. Using the non-Shannonian information-theoretic concepts we bridge the inference of causality and understanding of the occurrence of extreme events.

Supported by the Czech Academy of Sciences, Praemium Academiae awarded to M. Paluš.

[1] N. Wiener, in: E. F. Beckenbach (Editor), Modern Mathematics for Engineers (McGraw-Hill, New York, 1956)

[2] C.W.J. Granger, Econometrica 37 (1969) 424

[3] K. Hlaváčková-Schindler  et al., Phys. Rep. 441 (2007)  1; M. Paluš, M. Vejmelka, Phys. Rev. E 75 (2007) 056211; J. Runge et al., Nature Communications 6 (2015) 8502

[4] M. Paluš, Phys. Rev. Lett. 112 (2014) 078702; N. Jajcay, J. Hlinka, S. Kravtsov, A. A. Tsonis, M. Paluš, Geophys. Res. Lett. 43(2) (2016) 902–909

How to cite: Paluš, M.: Non-Shannonian information theory connects inference of causality and understanding of extreme events, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-10707, https://doi.org/10.5194/egusphere-egu23-10707, 2023.

This research investigated the applicability of a probabilistic physics-informed Deep Learning (DL) algorithm, i.e.,deep autoregressive network (DeepAR), for rainfall-runoff modeling across the continental United States (CONUS). Various catchment physical parameters were incorporated into the probabilistic DeepAR algorithm with various spatiotemporal variabilities to simulate rainfall-runoff processes across Hydrologic Unit Code 8 (HUC8). We benchmarked our proposed model against several physics-based hydrologic approaches such as Sacramento Soil Moisture Accounting Model (SAC-SMA), Variable Infiltration Capacity (VIC), Framework for Understanding Structural Errors (FUSE), Hydrologiska Byråns Vattenbalansavdelning (HBV), and the mesoscale hydrologic model (mHM). These approaches were implemented using Catchment Attributes and Meteorology for Large-sample Studies (CAMELS), Maurer datasets. Analysis suggested that catchment physical attributes such as drainage area have significant impacts on rainfall-runoff generation mechanisms while catchment fraction of carbonate sedimentary rocks parameter’s contribution were insignificant. The results of the proposed physics-informed DeepAR simulation were comparable and somewhat superior to the well-known conceptual hydrologic models across CONUS.  

How to cite: Sadeghi Tabas, S. and Samadi, V.: A Probabilistic Physics-informed Deep Learning Model for Rainfall-runoff Prediction across Continental United States, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-11222, https://doi.org/10.5194/egusphere-egu23-11222, 2023.

EGU23-13068 | ECS | PICO | HS1.3.2

Identifying the drivers of lake level dynamics using a data-driven modeling approach 

Márk Somogyvári, Ute Fehrenbach, Dieter Scherer, and Tobias Krueger

The standard approach of modeling lake level dynamics today is via process-based modeling. The development of such models requires an extensive knowledge about the investigated system, especially the different hydrological flow processes. When some of this information is missing, these models could provide distorted results and could miss important system characteristics.

In this study, we show how data-driven modeling can help the identification of the key drivers of lake level changes. We are using the example of the Groß Glienicker Lake, a glacial, groundwater fed lake near Berlin. This lake has been experiencing a drastic loss of water in recent decades, whose trend became even faster in the last few years. There is a local controversy whether these changes are mainly weather driven, or caused by water use; and what mitigation measures could be used to counteract them. Due to the strong anthropogenic influence from multiple water-related facilities near the lake, and the lack of geological information from the catchment, there are many unknows about the properties of the hydrological processes, hence the development of a process-based model in the area is challenging. To understand the system better we combine data-driven models with water balance approaches and use this methodology as an alternative to classic hydrological modeling.

The climatic model input (catchment-average precipitation and actual evapotranspiration) is generated by the Central European Refinement dataset (CER), which is a meteorological dataset generated by dynamically downscaling the Weather Research and Forecasting model (Jänicke et al., 2017). First, a data-driven model is constructed to predict the changes in lake levels one day ahead by using precipitation and evapotranspiration values from the last two months, a time interval that was selected after an extensive parameter analysis. This model is then further extended by additional inputs, such as water abstraction rates, river and groundwater levels. The fits of the different simulated lake levels are evaluated to identify the effects of the relevant drivers of the lake level dynamics. For a more mechanistic interpretation, a monthly water balance model was created using the same dataset. By calculating the different fluxes within the system, we were able to estimate the magnitudes of unobserved hydrological components.

With the help of our modeling approach, we could rule out the influence of one of the nearby waterworks and a river. We have also found that the lake level dynamics over the last two decades was mainly weather-driven, and the lake level fluctuations could be explained with changes in precipitation and evapotranspiration. With the water balance modeling, we have shown that the long-term net outflux from the lake catchment has increased in the last few years. These findings are used to support the development of a local high-resolution hydrogeological model, which could be used to further analyze these processes.

References

Jänicke, B., Meier, F., Fenner, D., Fehrenbach, U., Holtmann, A., Scherer, D. (2017): Urban-rural differences in near-surface air temperature as resolved by the Central Europe Refined analysis (CER): sensitivity to planetary boundary layer schemes and urban canopy models. Int. J. Climatol. 37 (4), 2063-2079. DOI: 10.1002/joc.4835

How to cite: Somogyvári, M., Fehrenbach, U., Scherer, D., and Krueger, T.: Identifying the drivers of lake level dynamics using a data-driven modeling approach, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-13068, https://doi.org/10.5194/egusphere-egu23-13068, 2023.

Streamflow monitoring is a key input to water resource management, as it is an important source of information for understanding hydrological processes and prediction catchment behaviour and resulting flows. Both the monitored and the predicted flows support important decisions in areas such as infrastructure design, flood forecasting and resource allocation. It is therefore essential that the predictive information we have about our water resources serves these various needs.

Since observations are from the past and our decisions affect the future, models are needed to extrapolate measurements in time. Similarly, streamflow is not always measured at places where the information is needed, so interpolation or extrapolation is needed in space or across catchment properties and climates. Recent advances in publicly available large datasets of streamflow records and corresponding catchment characteristics have enabled succesful applications of machine learning to this prediction problem, leading to increased predictability in ungauged basins.

Since information content is related to surprise, we could see the objective of monitoring networks as manufacturing surprising data. This is formalized in approaches for monitoring network design based on information theory, where often the information content of the sources, i.e. the existing monitoring stations, has been investigated, including the effects of redundancy due to shared information between stations.

In this research, we argue that information content is related to unpredictability, but is inevitably filtered through several layers, which should be considered for monitoring network design. Examples of such filters are the models used for extrapolation to ungauged sites of interest, the target statistics of interest to be predicted, and the decision making purpose of those predictions. This means that the optimal monitoring strategy (where to measure, with how much precision and resolution, and for how long) depend on evolving modeling capabilities and representation of societal needs. Also, biases in the current neworks may exist as a function of how they are funded.

In this presentation, these theoretical aspects are investigated with examples from an ongoing project to investigate the streamflow monitoring network in British Columbia, Canada, which recently experienced record-breaking floods. 

How to cite: Weijs, S., Werenka, A., and Kovacek, D.: Manufacturing surprise: How information content, modeling capabilities and decision making purpose influence optimal streamflow monitoring, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-14704, https://doi.org/10.5194/egusphere-egu23-14704, 2023.

EGU23-15968 | PICO | HS1.3.2

Differentiable modeling to unify machine learning and physical models and advance Geosciences 

Chaopeng Shen, Alison Appling, Pierre Gentine, Toshiyuki Bandai, Hoshin Gupta, Alexandre Tartakovsky, Marco Baity-Jesi, Fabrizio Fenicia, Daniel Kifer, Xiaofeng Liu, Li Li, Dapeng Feng, Wei Ren, Yi Zheng, Ciaran Harman, Martyn Clark, Matthew Farthing, and Praveen Kumar

Process-Based Modeling (PBM) and Machine Learning (ML) are often perceived as distinct paradigms in the geosciences. Here we present differentiable geoscientific modeling as a powerful pathway toward dissolving the perceived barrier between them and ushering in a paradigm shift. For decades, PBM offered benefits in interpretability and physical consistency but struggled to efficiently leverage large datasets. ML methods, especially deep networks, presented strong predictive skills yet lacked the ability to answer specific scientific questions. While various methods have been proposed for ML-physics integration, an important underlying theme  — differentiable modeling — is not sufficiently recognized. Here we outline the concepts, applicability, and significance of differentiable geoscientific modeling (DG). “Differentiable” refers to accurately and efficiently calculating gradients with respect to model variables, critically enabling the learning of high-dimensional unknown relationships. DG refers to a range of methods connecting varying amounts of prior knowledge to neural networks and training them together, capturing a different scope than physics-guided machine learning and emphasizing first principles. In this talk we provide examples of DG in global hydrology, ecosystem modeling, water quality simulations, etc. Preliminary evidence suggests DG offers better interpretability and causality than ML, improved generalizability and extrapolation capability, and strong potential for knowledge discovery, while approaching the performance of purely data-driven ML. DG models require less training data while scaling favorably in performance and efficiency with increasing amounts of data. With DG, geoscientists may be better able to frame and investigate questions, test hypotheses, and discover unrecognized linkages. 

How to cite: Shen, C., Appling, A., Gentine, P., Bandai, T., Gupta, H., Tartakovsky, A., Baity-Jesi, M., Fenicia, F., Kifer, D., Liu, X., Li, L., Feng, D., Ren, W., Zheng, Y., Harman, C., Clark, M., Farthing, M., and Kumar, P.: Differentiable modeling to unify machine learning and physical models and advance Geosciences, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-15968, https://doi.org/10.5194/egusphere-egu23-15968, 2023.

EGU23-16510 | PICO | HS1.3.2 | Highlight

Evolution of Causal Structure of Interactions in Turbulence at the Biosphere-Atmosphere interface 

Praveen Kumar and Leila Hernandez Rodriguez

Turbulence at the biosphere-atmosphere interface refers to the presence of chaotic and chaotic-like fluctuations or patterns in the exchange of energy, matter, or information between the biosphere and atmosphere. These fluctuations can occur at various scales. Turbulence at the biosphere-atmosphere interface can affect the transfer of heat, moisture, and gases. In this study, we use causal discovery to explore how high-frequency data (i.e., 10 Hz) of different variables at a flux tower, such as wind speed, air temperature, and water vapor, exhibit interdependencies. We use Directed Acyclic Graphs (DAGs) to identify how these variables influence each other at a high frequency. We tested the hypothesis that there are different types of DAGs present during the daytime at the land-atmosphere interface, and we developed an approach to identify patterns of DAGs that have similar behavior. To do this, we use distance-based classification to characterize the differences between DAGs and a k-means clustering approach to identify the number of clusters. We look at sequences of DAGs from 3-minute periods of high-frequency data to study how the causal relationships between the variables change over time. We compare our results from a clear sky day to a solar eclipse to see how changes in the environment affect the relationships between the variables. We found that during periods of high primary productivity, the causal relationship between water vapor and carbon dioxide shows a strong coupling between photosynthesis and transpiration. At high frequencies, we found that thermodynamics influences the dynamics of water vapor and carbon dioxide. Our framework makes possible the study of how dependence in turbulence is manifested at high frequencies at the land-atmosphere interface.

How to cite: Kumar, P. and Rodriguez, L. H.: Evolution of Causal Structure of Interactions in Turbulence at the Biosphere-Atmosphere interface, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-16510, https://doi.org/10.5194/egusphere-egu23-16510, 2023.

Recent years have seen an uptick in the frequency of flood records occurring in the United States, with South Carolina (SC) being particularly hard hit. This study developed various deep recurrent neural networks (DRNNs) such as Vanilla RNN, long short-term memory (LSTM), and Gated Recurrent Unit (GRU) for flood event simulation. Precipitation and the USGS gaging data were preprocessed and fed into the DRNNs to predict flood events across several catchments in SC. The DRNNs are trained and evaluated using hourly datasets, and the outcomes were then compared with the observed data and the National Water Model (NWM) simulations. Analysis suggested that LSTM and GRU networks skillfully predicted the shape of flood hydrographs, including rising/falling limb, peak rates, flood volume, and time to peak, while the NWM vastly overestimated flood hydrographs. Among different climatic variables that were forced into the DRNNs, rainfall amount and spatial distribution were the most dominant input variables for flood prediction in SC.

How to cite: Heidari, E. and Samadi, V.: Application of Deep Recurrent Neural Networks for Flood Prediction and Assessment, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-16678, https://doi.org/10.5194/egusphere-egu23-16678, 2023.

HS2 – Catchment hydrology

HS2.1 – Catchment hydrology in diverse climates and environments

EGU23-451 | ECS | Posters on site | HS2.1.1

How often did Mediterranean regions transition to different hydroclimatic regimes in the last millennium? 

Arnau Sanz i Gil, Akbar Rahmati Ziveh, Hossein Abbasizadeh, Vishal Thakur, Martin Hanel, Petr Maca, Oldrich Rakovec, and Yannis Markonis

The Mediterranean has been characterized as a region of enhanced climatic variability. Transitions between dry and wet conditions have repeatedly occurred over the last millennium in various spatial and temporal scales. However, the frequency of these shifts is poorly assessed due to the low amount of paleoclimatic reconstructions and the substantial heterogeneity of the Mediterranean. Here, we examine how often Mediterranean regions have transitioned between different hydroclimatic regimes over the last millennium. For this purpose, we use the Paleo Hydrodynamics Data Assimilation (PHYDA) simulation results to identify transitional changes based on Köppen-Geiger climate types. Our results indicate which regions are more likely to experience transitions between hydroclimatic regimes and their duration distribution. We also examine how the intensity of the shifts have fluctuated during the study period and quantify the uncertainties involved. Our findings contribute to a better understanding of the past hydroclimatic variability, which is crucial for further determining the current state and future aridification in the Mediterranean region.  

How to cite: Sanz i Gil, A., Rahmati Ziveh, A., Abbasizadeh, H., Thakur, V., Hanel, M., Maca, P., Rakovec, O., and Markonis, Y.: How often did Mediterranean regions transition to different hydroclimatic regimes in the last millennium?, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-451, https://doi.org/10.5194/egusphere-egu23-451, 2023.

EGU23-3345 | ECS | Posters on site | HS2.1.1

Evaluating the Impact of Topography on Satellite-Derived Evapotranspiration Estimates in the High Atlas Mountains of Morocco 

Badr-eddine Sebbar, Olivier Merlin, Saïd Khabba, Victor Pénot, Vincent Simonneaux, Marine Bouchet, and Abdelghani Chehbouni

Accurate evapotranspiration (ET) estimates in mountainous regions are needed for better understanding the hydrological cycle and managing water resources within watersheds. However, the complex topography of these areas can have significant effects on ET, making it challenging to monitor at all scales. In this study, we sought to improve the accuracy of thermal remote sensing-based ET estimates in the High Atlas region of Morocco by taking into account the effect of topography. To do this, we used two ET models, both driven by LANDSAT optical/thermal data: the Two-Source Energy Balance (TSEB) model and the contextual Water Deficit Index (WDI) model. The meteorological data (such as air temperature, wind speed, and humidity) used to force the models were taken from ERA5-Land reanalysis products and specifically disaggregated at 30 meters to account for elevation effects, while the solar radiation data were obtained using the Samani et al. method to consider sun exposure effects. We compared the ET estimates produced by both models to measurements taken at two Eddy covariance towers in the mountains at different elevations (900 and 3850 m.a.s.l). Our results showed that the TSEB model was able to accurately estimate ET in the region, with a high level of consistency (r² = 0.72, rmse = 43 Wm-2). The relative performance of both TSEB and WDI models was assessed. We also found that topography significantly influences ET in the High Atlas Mountains, emphasizing the importance of considering it when estimating ET at the watershed scale. This outcome can be used to better understand the hydrological cycle and manage water resources in mountainous areas.

How to cite: Sebbar, B., Merlin, O., Khabba, S., Pénot, V., Simonneaux, V., Bouchet, M., and Chehbouni, A.: Evaluating the Impact of Topography on Satellite-Derived Evapotranspiration Estimates in the High Atlas Mountains of Morocco, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-3345, https://doi.org/10.5194/egusphere-egu23-3345, 2023.

EGU23-3584 | Orals | HS2.1.1

Assessing urban water supply from karstic groundwater reservoirs through two hydrological models and the Exploitation Index in the southeast of Spain 

Teresa Alejandra Palacios Cabrera, Antonio Jodar Abellan, Damaris Núñez Gómez, Pablo Melgarejo, Derdour Abdessamed, Ryan Bailey, and Seyed Babak Haiji Seyed

Assessing urban water supply from karstic groundwater reservoirs through two hydrological models and the Exploitation Index in the southeast of Spain

Teresa Palacios-Cabrera1, Antonio Jodar-Abellan2, Ryan T. Bailey3, Dámaris Núñez-Gómez2, Derdour Abdessamed4, Seyed Babak Haji Seyed Asadollah5, Pablo Melgarejo2

1Faculty of Geology, Mines, Petroleum and Environmental Engineering. Central University of Ecuador. teresaalejandrap3@gmail.com

2Centro de Investigación e Innovación Agroalimentario y Agroambiental (CIAGRO), Miguel Hernández University (UMH). Orihuela, Spain.

3Dept. of Civil and Environmental Engineering, Colorado State University, Fort Collins, CO, USA.

4Laboratory for the Sustainable Management of Natural Resources in Arid and Semi‑arid Zones. University Center Salhi Ahmed Naama (Ctr Univ Naama). P.O. Box 66, Naama 45000. Algeria.

5Department of Civil Engineering, Science and Research Branch, Islamic Azad University, Tehran, Iran.

Abstract:

Nowadays, numerous urban settlements in arid and semiarid areas are supplied by groundwater from adjacent small aquifers. Climate change with expected decreases in averages precipitation values jointly with increases in the frequency of heavy rainfall events does not show a clear pattner to how water resources in karstic aquifers are going to evolve. This work, focused in the Guadalest watershed (province of Alicante, southeast of Spain) assesses the behaviour of four karstic aquifers (the Mela, Beniardá-Polop, Benimantell and Serralla-Aixorta aquifers), whose resources supply urban water consumption for close municipalities. In these aquifers, we estimate groundwater recharge, extractions and their relation within the Exploitation Index (EI) by using the SWAT and SIMPA models, previously calibrated and validated in this watershed, during the period 1980-2016. These groundwater estimations were tested (validated) with field measurements performed by local authorities during the above mentioned period. Thus, in the Mela aquifer an EI of 0.19 was estimated with SWAT and SIMPA while an EI of 0.13 was obtained by local authorities; in the Beniardá-Polop aquifer an EI of 1.43 was estimated while an EI of 1.26 was obtained in the fieldwork; in Benimantell an EI of 0.25 and an EI of 0.22 were estimated and obtained respectively; and finally in the Serralla-Aixorta aquifer an EI of 0.19 and an EI of 0.2 were estimated and obtained respectively. Our results denote that: i) both models simulate correctly groundwater abstractions; ii) assessed aquifers depict a clear reduction of their reserves during the study period which represent an important issue considering that currently groundwater extractions are the unique water source of these populations. Therefore, it will be necessary to design supply strategies for these inhabitants and to carry out them, meeting budget restrictions and avoiding potential water shortages.

Keywords: groundwater; SWAT; SIMPA; Exploitation Index; urban water supply; southeast of Spain.

How to cite: Palacios Cabrera, T. A., Jodar Abellan, A., Núñez Gómez, D., Melgarejo, P., Abdessamed, D., Bailey, R., and Haiji Seyed, S. B.: Assessing urban water supply from karstic groundwater reservoirs through two hydrological models and the Exploitation Index in the southeast of Spain, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-3584, https://doi.org/10.5194/egusphere-egu23-3584, 2023.

EGU23-6360 | ECS | Orals | HS2.1.1

Trend analysis on eco-hydrological indicators as management tools in Mediterranean Environmental Protected Areas: The case study of Sierras Subbéticas Natural Park (Spain) 

Ana Calbet, Ana Andreu, Javier Aparicio, María José Polo, Pedro Torralbo, and Rafael PImentel

Mountain areas constitute the headwaters of river basins, biodiversity hot-spots, and have a high value as ecosystem resources provision zones. Within the context of climate change, their meteorological trends and projections of future climate scenarios show a high resource vulnerability, highlighting the need to reduce the uncertainty associated with the dynamics of ecological-hydrological-meteorological processes. In these semiarid regions, there is a generalised increase in temperature, especially in summer, a decrease in average annual precipitation with an increase in torrentiality, and a decrease in snow's frequency and persistence. These can change the vegetation's phenological cycle, behaviour, and distribution. In addition, the socio-economic activities linked to these rural Mediterranean systems would be affected.

 

This study aims to establish a bridge between the different sources of available ecological-hydrological-meteorological information  and the local information that the final user needs, defining eco-hydrological indicators. Our long-term goal is to improve the management and conservation of Mediterranean mountains in the framework of climate change adaptation. 

 

For this purpose, we carried out a spatiotemporal analysis of precipitation and temperature historical trends (1960-2022, with nonparametric Mann-Kendall (MK) statistical test) as basic eco-hydrological indicators in the pilot area of the Sierras Subbéticas Natural Park (1570 m.a.s.l.) a  representative Mediterranean Mountain Range (Southern, Spain). This analysis constitutes the basis for the definition of targeted eco-hydrological management indicators. Among the different management challenges identified (e.g., sustainable olive tree production, preservation of autochthonous forest formations, water availability in groundwater reservoirs), we focus on the conservation of natural holm oak forest. Therefore, we selected as a targeted eco-hydrological indicator the occurrence of extreme drought periods in spring (3-months SPI in June), which is considered a primary meteorological factor influencing leaf development.

 

The trends analysis’ results reflect a significant increase in average annual mean temperatures, especially in the central and lowest areas of the mountain range. Regarding annual precipitation, there is great variability between dry and wet years, with a decreasing trend (-0,821 mm/year) without statistical significance. In the same way, the selected eco-hydrological indicator shows a non statistically significant trend.  This index directly influences the maintenance and regeneration of the Natural Park forest masses, which are of particular interest for managing its ecosystem services. In addition, this indicator constitutes an example of how these specific indicators allow us to use climatic-hydrological data sources in a practical application, with the future goal of integrating meteorological forecasts into the pipeline.

Acknowledgment: This work has been funded by project MONADA - "Hydrometeorological trends in mountainous protected areas in Andalusia: examples of co-development of climatic services for strategies of adaptation to climatic change", with the economic collaboration of the European Funding for Rural Development (FEDER) and the Andalusian Office of Economic Transformation, Industry, Knowledge and Universities. R+D+i project 2020.

How to cite: Calbet, A., Andreu, A., Aparicio, J., Polo, M. J., Torralbo, P., and PImentel, R.: Trend analysis on eco-hydrological indicators as management tools in Mediterranean Environmental Protected Areas: The case study of Sierras Subbéticas Natural Park (Spain), EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-6360, https://doi.org/10.5194/egusphere-egu23-6360, 2023.

EGU23-6597 | Posters virtual | HS2.1.1

Irrigation timing retrieval at the plot scale using Surface Soil Moisture derived from Sentinel time series in Europe 

Michel Le Page, Thang Nguyen, Mehrez Zribi, Aaron Boone, Jacopo Dari, Sara Modanesi, Luca Zappa, Nadia Ouaadi, and Lionel Jarlan

The computation of the water budget of irrigated fields is generally difficult because of unknown irrigation amounts and timing. Automatic detection of irrigation events could greatly simplify the water balance of irrigated fields. The combination of high spatial resolution and high-frequency SAR (Sentinel-1) and optical satellite observations (Sentinel-2) makes the detection of irrigation events potentially feasible. Indeed, optical observation allows following the crop development while SAR observation can provide an estimation of the Surface Soil Moisture (SSM). However, uncertainties due to acquisition configuration or crop geometry and density might affect the retrieval of SSM. Here, an algorithm for irrigation events detection is assessed considering several aspects that could affect SSM retrieval (incidence angle, crop type, crop development) and specific characteristics of irrigation events (irrigation frequency, frequency of observations). Additionally, an alternative soil water budget model, the force-restore approach, is compared with the original bucket soil water budget algorithm. A European dataset of irrigation events collected during the ESA Irrigation+ project (5 sites in France, Germany, and Italy over three years) is used. The performances are analyzed in terms of the F‑score and the seasonal sum of irrigation. Overall, the analysis corroborated that the scores decrease with SSM observation frequency. The impact of the Sentinel-1 configuration (ascending/descending, close to 39°/far from 39°) on the retrieval results is low. The lower scores obtained with small NDVI compared to large NDVI were almost systematic, which is counter-intuitive, but might have been due to the larger number of irrigation events during high vegetation periods. The scores decreased as irrigation frequency increased, which was substantiated by the fact that the scores were better in France (more sprinkler irrigation) than in Germany (more localized irrigation). The strategy of merging different runs versus the strategy of interpolating all SSM data for one run has produced comparable results. The estimated cumulative sum of irrigation was around -20% lower compared to the reference dataset in the best cases. Finally, the replacement of the original SSM model by the Force-restore provided an improvement of about 6% on the F‑score, and also narrowed the error on cumulative seasonal irrigation. This study opens new perspectives for the advancement of irrigation retrieval at large scale based on SSM data sets through an in-depth analysis of results as a function of satellite configuration, irrigation techniques, and crops.

How to cite: Le Page, M., Nguyen, T., Zribi, M., Boone, A., Dari, J., Modanesi, S., Zappa, L., Ouaadi, N., and Jarlan, L.: Irrigation timing retrieval at the plot scale using Surface Soil Moisture derived from Sentinel time series in Europe, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-6597, https://doi.org/10.5194/egusphere-egu23-6597, 2023.

EGU23-6661 | ECS | Posters on site | HS2.1.1

Assessment of factors controlling the runoff coefficient in the Mediterranean context: a case study in central Italy 

Arash Rahi, Mehdi Rahmati, Jacopo Dari, Carla saltalippi, and Renato Morbidelli

Global warming is affecting hydroclimatic parameters determining changes in temperature and precipitation patterns. In addition, human-induced activities act on the land use and land cover (LULC) features of catchments. Runoff generation can be affected by these factors in both natural and anthropogenic basins. The aim of the current study is to investigate the relationship between the runoff coefficient (Rc), computed by exploiting long-term rainfall and streamflow records, and several features that can potentially affect it, namely meteorological parameters, soil water storage (SWS), and LULC changes through the wavelet coherence analysis. The method has been applied over the Upper Tiber basin at Ponte Nuovo outlet, in central Italy. To facilitate the understanding of the current catchment conditions in terms of surface water availability, a trend analysis has been performed using the Mann-Kendall (MK) test. For the long-term period of 1927-2020, the results reveal a decreasing trend of Rc. In addition, the MK test for seasonal temperature and SWS shows increasing and decreasing trends, respectively. Based on the wavelet analysis, a significant positive correlation is observed between Rc and SWS in the annual cycle with a phase shift of less than one month, while a strong negative correlation is observed between Rc and temperature in the annual period with a phase shift of 3-6 months. The study of the relationship between Rc and LULC changes shows a weak correlation. The lower phase shift between Rc and SWS indicate that Rc is susceptible to SWS in a faster way than other components. These results allows a better understanding of the main factors influencing the Rc over the pilot area; moreover, an extension to other Mediterranean basins is foreseen as a follow-up of this work.

How to cite: Rahi, A., Rahmati, M., Dari, J., saltalippi, C., and Morbidelli, R.: Assessment of factors controlling the runoff coefficient in the Mediterranean context: a case study in central Italy, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-6661, https://doi.org/10.5194/egusphere-egu23-6661, 2023.

EGU23-6734 | ECS | Orals | HS2.1.1

Importance of baseflow contribution in mountainous Mediterranean watersheds highlighted by geochemical and isotope tracers 

Pierre-Alain Guisiano, Sébastien Santoni, Frédéric Huneau, Émilie Garel, and Alexandra Mattei

Most of the Mediterranean basin coasts are bordered by high mountain ranges (Atlas e.g.). As a result, most of the coastal socio-economic activities are highly dependent on the availability of water from mountainous catchment areas. However, these resources are increasingly vulnerable to climate change, population growth and agricultural development. Given the seasonality of rainfall with high water deficit during summer, groundwater covers a large part of the water supply and appears to be also essential to maintain river flows as well as their ecological continuity. However, one of the most important knowledge gap remains in the characterization and quantification of the watershed contributors supplying river flow through time and space. And this is especially the case for groundwater and delayed subsurface flow. Therefore, the aim of our research consisted in characterizing the baseflow component, as the contribution coming from groundwater and delayed subsurface flow, over two full hydrological years for selected representative mountainous watersheds: The Tavignanu and Fium’Altu basins (Corsica, France). Due to its location in the western Mediterranean basin as well as its diversity in catchment morphologies and lithologies, Corsica is an excellent observatory of any mountainous hydrological processes. In this purpose, different promising tools scarcely used in the Mediterranean context are available to perform baseflow analysis:

- On the one hand, the non-tracer-based methods, including several technics ranging from an empirical to an analytical basis

- On the other hand, the tracer-based methods including the use of water stable isotopes and hydrogeochemical tracers in a mass balance procedure

It allowed to test and highlight the high potential of hydrogeochemical tools in the Mediterranean mountainous context in many ways:

- By correlating, calibrating and validating some of the non-tracer-based methods with monthly tracer data for a Mediterranean use

- By using the validated non-tracer-based methods to perform continuous baseflow separation on a daily basis in order to assess baseflow seasonal patterns and trends over the last twenty years on both catchments

Thus, we clearly highlighted that baseflow, over the years, constitute the main contributor to river flow during dry periods (with a mean Baseflow Index up to 93% for both catchments) and still remains as an important part during high flow periods (with a mean contribution of 67% for the Tavignanu and 73% for the Fium’Altu basin). Therefore, we showed the importance of groundwater and delayed subsurface flow contributions to sustain river flow and its ecological continuity in a mountainous Mediterranean context. Geological features may explain differences in the Baseflow Index distribution between the two basins, implying that some components in the baseflow (groundwater or subsurface flow) are more or less present depending on the period considered. Our next steps consist in going further using environmental tracers to provide conceptual models describing all components of the hydrological cycle which contribute to baseflow. At the end, this will serve as indicators for stakeholders in order to perform sustainable management and to assess the resilience of water resources facing global climate change, not only in Corsica, but for any similar region.

How to cite: Guisiano, P.-A., Santoni, S., Huneau, F., Garel, É., and Mattei, A.: Importance of baseflow contribution in mountainous Mediterranean watersheds highlighted by geochemical and isotope tracers, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-6734, https://doi.org/10.5194/egusphere-egu23-6734, 2023.

EGU23-7444 | ECS | Posters virtual | HS2.1.1

Hydrological modeling using an improved algorithm for a better evaluation of the snow water equivalent (SWE) during spring floods in the Moroccan High Atlas Mountains. 

Myriam Benkirane, simon Gascoin, Abdelhakim Amazirh, Laura Sourp, Nour-Eddine Laftouhi, and Said Khabba

The present study aims to evaluate the performance of a hydrological model to simulate spring runoff processes, analyze the effect of snowmelt on seasonal flow, and identify the snowmelt contribution rate based on the snow water equivalent (SWE) in the Moroccan High Atlas watersheds.

The main objective of this study is to evaluate the daily SWE in a poorly instrumented mountainous watershed using an improved hydrological model. The model algorithm improvement is considered an essential approach for better understanding the initial basin conditions that influence these hydrogeological behaviors. For this purpose, a seasonal analysis was performed to select flood events that reproduce this phenomenon.

To this end, the calibration has been done by forcing the model with rainfall, runoff, temperature, and snow water equivalent (SWE), with an amelioration of the model algorithm. Interestingly enough, this improvement achieved 13% based on the Nash-Sutcliffe efficiency coefficients. Hence, the spring event flows were influenced by the snowmelt process, these results will have direct implications for flood event replication modeling and flood forecasting in these regions.

The study demonstrates that this region is sensitive to the seasonal effect of snowmelt. Therefore, it is essential to take into account the contribution of snow in hydrological studies developed at the level of the Moroccan High Atlas mountainous watersheds. This approach is a great challenge that will improve the reproduction of seasonal flood events and allow a better forecast of flood events to reduce the uncertainties and risks of flooding in mountainous basin areas facing the same climate conditions.

Keywords: Precipitation, SWE, Hydrological modeling, Calibration, Mediterranean climate, flood events, Zat basin.

How to cite: Benkirane, M., Gascoin, S., Amazirh, A., Sourp, L., Laftouhi, N.-E., and Khabba, S.: Hydrological modeling using an improved algorithm for a better evaluation of the snow water equivalent (SWE) during spring floods in the Moroccan High Atlas Mountains., EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-7444, https://doi.org/10.5194/egusphere-egu23-7444, 2023.

EGU23-7854 | ECS | Posters virtual | HS2.1.1

Modeling the Impact of Global Warming on the Phenology of the Olive Tree in the Mediterranean region 

Aicha Moumni, Iman Abouseir, and Abderrahman Lahrouni

Nowadays, there is observable evidence from all continents and most oceans that many natural systems have been affected by regional climate changes, particularly by the increase in temperature. This increase has also influenced the phenology of plants. As the olive tree is a plant characterizing the Mediterranean area, it is obvious that its phenology could serve as an indicator of the impact of global warming on this area. In this study, we will use the PMP model and observations of the tree phenology to predict its flowering date, which is the most remarkable and easiest to observe development phase. On the other hand, we will study by simulation the impact of climate change on the flowering of the olive tree under the conditions of Haouz of Marrakech according to three contrasting scenarios of a possible climate change. The PMP software is a tool that facilitates the development of mechanistic phenological models. It is based on thermal time calculations. In the present work, we chose to test three thermal time models: the ForcTT model, the TT model and the UniForc unified forcing model. The first two models are two versions of Growing Degree Days (GDD) which corresponds to a linear relationship of forcing rate from the initial date t0 and a threshold temperature Tb. The third UniForc model is a sigmoidal function of temperature with the initial time t0 as an unknown. The tests were carried out using two databases, the first recorded in the meteorological stations of the Haouz region covering the period 1985 - 2012 and the second observed on the phenology of the olive tree in the Tassaout area for the periods 1986 - 1991 and 1997 - 2012. The first result obtained shows that the UniForc is the most robust model, it is therefore retained for the study of the impact of global warming on the olive tree.In the second part of this work we have chosen three scenarios of greenhouse gas emissions, SRES (Special Report on Emissions Scenarios), which explore future development paths (demographic, economic and technological). Each of the three scenarios chosen is based on a degree of temperature increase according to the imagined development pathway: the more optimistic B1 scenario (increase of 1.1°C), the medium degree A1B scenario (increase of 2.8°C) and the more pessimistic A1F1 scenario (increase of 6.4°C). All the simulations carried out according to the chosen SRES scenarios confirm that the increase in temperature leads to the advancement (earliness) of the flowering date, this advancement varies between 0.3 and 27.3 days. The higher the temperature increase, the earlier the flowering date. Thus, the flowering date of the olive tree is univocally linked to the type of greenhouse gas emission scenario chosen. Our results therefore confirm that this agronomic variable is a good indicator of the severity of global warming that could occur in the region.

How to cite: Moumni, A., Abouseir, I., and Lahrouni, A.: Modeling the Impact of Global Warming on the Phenology of the Olive Tree in the Mediterranean region, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-7854, https://doi.org/10.5194/egusphere-egu23-7854, 2023.

EGU23-7926 | ECS | Orals | HS2.1.1

Interactions between meteorological and agricultural droughts at different temporal and spatial scales 

kaoutar oukaddour, Younes Fakir, and Michel Le Page

The Tensift basin is prone to drought and, with the increasing frequency of extreme events, their forecasting and monitoring are becoming more complex. The present work aims to shed light on the interactions between meteorological and agricultural droughts while using multiple drought indices, and analyzing its temporal and spatial patterns over the Tensift basin in Morocco. To this purpose, we initially performed a trend analysis of the main parameters used in this study namely precipitation, temperature, NDVI, and soil moisture using the Mann-Kendall test. Moreover, a data-driven approach was adopted here to reveal the impact of lack of precipitation on the soil and vegetation cycles. Remote sensing data of precipitation from ERA5Land and soil moisture data from ESA-CCI as well as land surface temperature and NDVI from MODIS are used to calculate the standardized precipitation index (SPI), the vegetation condition index (VCI), the temperature condition index (TCI), and the soil moisture condition index (SMCI) for the period 2001–2021. A comparison analysis was conducted to test the performance and concordance of the indices. Then, to analyze the propagation of meteorological drought to the other components we conducted a cross-correlation study between drought indices.  The results reveal an upward trend of NDVI which is noticeable from the first decade (2009) and is attributed to the development of irrigated areas in this period. In contrast, the basin has shown a significant decline in monthly soil moisture for the period extending from 2001 to 2021, which could be explained by the way how soil moisture is retrieved in the ESA CCI product, and the trend in vegetation. On the other hand, the monthly precipitation and land surface temperature time series show no significant trend. The comparison between the indices showed moderate to low agreement. Correlations between TCI and SPI were eventually negative and significant at small time scales. A moderate correlation was observed between SPI1, SPI3, and TCI (0.45). The strongest correlations between SMCI and SPI were found at the 3 and 6-month time scales. Furthermore, the concordance between VCI and SPI is stronger at larger SPI time scales, the best correlation was observed between the indices VCI and SPI at 12 months with a correlation coefficient of 0.44. The correlations in the Tensift basin reflect spatial heterogeneities where some indices are more prevailing than others. Lag analysis results demonstrate valuable insights into the leading and preceding behavior of different variables regarding SPI. Relevant responses were identified at short, mid, and long-term influence of precipitation deficits on soil moisture, vegetation, and temperature. The results of this study highlight the interest in analyzing drought with different indices dedicated to each type of drought in order to improve early warning systems and risk management strategies for semi-arid areas.

How to cite: oukaddour, K., Fakir, Y., and Le Page, M.: Interactions between meteorological and agricultural droughts at different temporal and spatial scales, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-7926, https://doi.org/10.5194/egusphere-egu23-7926, 2023.

EGU23-8147 | ECS | Posters virtual | HS2.1.1

Evaluation of two climate production satellites over the region of Marrakesh Safi Morocco 

el houcine el moussaoui, Aicha Moumni, Said Khabba, and Abderrahmane Lahrouni

Although weather stations provide accurate measurements of ground climate conditions in close proximity to the station, they are expensive and require periodic recording of measurements. In addition, weather stations are therefore distributed sparsely, especially in developing countries. Conversely, satellites see entire landscapes and are therefore able to offer precise measurements at each location. This paper compares the performance of satellite products with weather station observations at three sites characterized by different climates Ounagha, Chichawa, and R3 in Morocco.

Precipitation and temperature data over the period of 2 years (2018 - 2019) at the three sites were collected. Data based on satellite imagery were collected for two satellite products, namely ERA5 and POWER over a similar period. The data were compared and analyzed through inferential statistics such as the root-mean-square error (RMSE), and the coefficient of determination (R2  ). The results showed that the temperature minimum daily simulated using the ERA5 satellite reached the highest coefficient of determination R2 = 0.92, with RMSE=1.34 (daily for Ounagha), R2 = 0.94, and with RMSE=1.27 (daily for Chichawa), R2 = 0.96, and with RMSE=1.13 (daily for R3). The temperature maximum daily simulated through the POWER satellite showed the best coefficient of determination R2 =0.924 with RMSE=2.174 (Ounagha daily). In contrast, the ERA5 satellite presents a better coefficient of determination R2 =0.97 in Chichawa and R3 stations. The results of comparing the observed weather stations and the satellite data in terms of precipitation show that the acceptable performance was attributed to the ERA5 data for cumulative, decadaire, and monthly precipitation in the three sites.


The use of satellite products is a good way to solve the lack of weather stations and to make data available to the scientific community for further investigation. Furthermore, since our interest in monitoring drought in the Smimou region and our need for climate data in this area, which lacks a meteorological station, the results of this study encourage us to use the ERA5 satellite to collect climate data for the region.

How to cite: el moussaoui, E. H., Moumni, A., Khabba, S., and Lahrouni, A.: Evaluation of two climate production satellites over the region of Marrakesh Safi Morocco, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-8147, https://doi.org/10.5194/egusphere-egu23-8147, 2023.

EGU23-8268 | ECS | Posters virtual | HS2.1.1

Multi-Soil-Layering, the Emerging Technology for Wastewater Treatment: Review, Bibliometric Analysis, and Future Directions 

Sofyan Sbahi, Laila Mandi, Tsugiyuki Masunaga, Naaila Ouazzani, Abdessamad Hejja, and Abderrahman Lahrouni

Due to its unique structure and excellent purification efficiency (e.g., 98% for organic matter and between 94 and 100% for nutrients), multi-soil-layering (MSL) has emerged as an efficient eco-friendly solution for wastewater treatment and environmental protection. Through infiltration-percolation, this soil-based technology allows pollutants to move from the MSL upper layers to the outlet while maintaining direct contact with its media, which helps in their removal via a variety of physical and biochemical mechanisms. This paper attempts to comprehensively evaluate the application of MSL technology and investigate its progress and efficacy since its emergence. Thus, it will attempt via a bibliometric analysis using the Web of Science database (from 1993 to 01/06/2022) related to MSL technology, to give a clear picture of the number of publications (70 studies), the most active academics, and countries (China with 27 studies), as well as collaborations and related topics. Furthermore, through hybrid combinations, pollutant removal processes, MSL effective media, and the key efficiency parameters, this paper review will seek to provide an overview of research that has developed and examined MSL since its inception. On the other hand, the current review will evaluate the modeling approaches used to explore MSL behavior in terms of pollutant removal and simulation of its performance (R2 > 90%). However, despite the increase in MSL publications in the past years (e.g., 13 studies in 2021), many studies are still needed to fill the knowledge gaps and urging challenges regarding this emerging technology. Thus, recommendations on improving the stability and sustainability of MSLs are highlighted.

How to cite: Sbahi, S., Mandi, L., Masunaga, T., Ouazzani, N., Hejja, A., and Lahrouni, A.: Multi-Soil-Layering, the Emerging Technology for Wastewater Treatment: Review, Bibliometric Analysis, and Future Directions, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-8268, https://doi.org/10.5194/egusphere-egu23-8268, 2023.

EGU23-11935 | ECS | Posters virtual | HS2.1.1

Performance assessment of the DSSAT-CERES-Wheat model under different irrigation strategies in the semi-arid region of Marrakesh 

Lahoucine Ech-chatir, Salah Er-Raki, Abdelilah Meddich, Julio Cesar Rodriguez, and Said Khabba

Water scarcity is a major problem in the arid and semi-arid areas of Morocco, where irrigation is essential for agriculture. Crop growth models can enhance water use efficiency, thus providing an economic benefit while reducing pressure on water resources. In this study, we evaluated the modeling performance of the DSSAT-CERES-Wheat model in estimating Evapotranspiration (ETa), Total soil water (TSW), Grain yield, Tops weight and phenological stages of winter wheat in the semi-arid region of Tensift Al Haouz, Marrakech. The simulation was performed at a daily time step during two successive growing seasons 2002/2003 and 2003/2004. The model calibration was done firstly on two fields and ETa, TSW phenological stages, and productive variables were calibrated after the comparison of the simulated and observed data. Afterward, the validation was performed on four fields during the two growing seasons. The results showed that the model simulates reasonably good Grain yield, Tops weight and phenological stages. Moreover, The average values of  RMSE  between observed and measured ETa, TSW, Grain yield and Tops weight were respectively, 0.70mm/day, 25mm, 0.6 t/ha and 2 t/ha for the validation fields. Statistical parameters like R2, d, and NRMSE were additionally used and showed that the model simulates acceptably the above-mentioned parameters. Furthermore, The Penman-Monteith FAO56 and Priestley and Taylor Evapotranspiration simulation methods were compared, the average values of d  and R2 were respectively 0.85, 0.70 for the Penman-Monteith method, and 0.80, 0.65 for the Priestley and Taylor method. Thus, the DSSAT model can be considered a useful tool for monitoring the management of wheat in arid and semi-arid regions.

Keywords: DSSAT, wheat, irrigation, water scarcity, crop model

How to cite: Ech-chatir, L., Er-Raki, S., Meddich, A., Rodriguez, J. C., and Khabba, S.: Performance assessment of the DSSAT-CERES-Wheat model under different irrigation strategies in the semi-arid region of Marrakesh, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-11935, https://doi.org/10.5194/egusphere-egu23-11935, 2023.

EGU23-12908 | ECS | Posters virtual | HS2.1.1

Remote Sensing Monitoring of Flood hazard in Arid Environments. A Case Study of Saquia El Hamra Watershed Morocco 

Nafia El-alaouy, Aicha Moumni, Nour-Eddine Laftouhi, and Abderrahman Lahrouni

Floods are the most visible and destructive hydrologic phenomenon in terms of human and economic loss. Typically, flash floods are caused by large amounts of runoff due to short duration and high-intensity rainfall. Floods also lead to environmental and social problems, such as damage to roads, farms, and infrastructures and sometimes pollute surface water resources via the transfer of industrial waste, creating many health problems. In late October 2016, a flash flood severely damaged the surroundings of the city of Laayoune in the Saquia El Hamra basin in southern Morocco. The country’s climate is arid and semi-arid and is prone to destructive floods. The purpose of this study is to evaluate this flash flood and monitor wetland areas after this event using a technique that relies on remote sensing technology. This work was accomplished using Sentinel 2 satellite images, from the European Space Agency, based on classification methods and change detection techniques. Before and after the occurrence, the SVM classifier was employed to map land cover and land use. The overall accuracy (Kappa coefficient) was 94.41 % (0.91), and 87.33 % (0.81), respectively for both dates, when compared to the ground-truth data. The decision tree was built with the maps produced by the SVM classification for both dates as inputs, producing a change detection map with increased detail. The remote sensing technology has enabled us to monitor the damage that has been done to the area following the catastrophe with details on the buildings affected, farms flooded, and the extent of the river.

How to cite: El-alaouy, N., Moumni, A., Laftouhi, N.-E., and Lahrouni, A.: Remote Sensing Monitoring of Flood hazard in Arid Environments. A Case Study of Saquia El Hamra Watershed Morocco, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-12908, https://doi.org/10.5194/egusphere-egu23-12908, 2023.

EGU23-13882 | Orals | HS2.1.1 | Highlight

The impacts of future climate change on water security in the Mediterranean Basin 

Joris Eekhout and Joris de Vente

The Mediterranean Basin is classified as one of the hot-spots for climate change, where a significant decrease of precipitation and an increase of temperature are expected. This will most likely lead to a redistribution of water within Mediterranean catchments. However, the scale and magnitude and spatial differences of the impact of climate change on water security across the Mediterranean is still uncertain. Here we present the preliminary results of a systematic review on the impact of climate change on water security in the Mediterranean Basin. In this systematic review we focused on studies performed in the Mediterranean Basin that apply a hydrological model forced by climate model output and report changes in blue and/or green water, i.e. water stored in rivers and reservoirs (e.g. runoff or reservoir storage) and water stored in soils (e.g. groundwater recharge). The variables obtained from the studies include variables related to study area, climate and hydrological models, and model output. Our preliminary results show that the general tendency is a decrease of precipitation and an increase of temperature, which will cause a decrease of projected blue and green water. This will have serious consequences for the potential of irrigated agriculture, industry and household water use in the Mediterranean Basin, which heavily rely on the availability of blue water. But also for rainfed agriculture, where a decrease of green water may force farmers to abandon their land or transform to irrigated agriculture.

We acknowledge funding from the Spanish Ministry of Science and Innovation (AEI) (PID2019-109381RB-I00/AEI/10.13039/501100011033).

How to cite: Eekhout, J. and de Vente, J.: The impacts of future climate change on water security in the Mediterranean Basin, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-13882, https://doi.org/10.5194/egusphere-egu23-13882, 2023.

EGU23-14819 | ECS | Orals | HS2.1.1

C-band Sentinel-1 data for estimating the basal crop coefficient and evapotranspiration of winter wheat  

Nadia Ouaadi, Lionel Jarlan, Saïd Khabba, Michel Le Page, Adnane Chakir, Salah Er-Raki, and Pierre-Louis Frison

Estimating crop evapotranspiration (ETc) is of primary importance for irrigation management. The model commonly used for this purpose is the FAO-56 approach which consists of accurately estimating the basal crop coefficient Kcb. Historically, Kcb is derived from optical indices such as NDVI giving its sensitivity to vegetation cover fraction and to the Leaf Area Index. Nevertheless, optical data are disturbed by the presence of clouds. In this context, the objective of this work is to investigate the potential use of all-weather radar data as a substitute of NDVI to derive Kcb. The study is conducted over two winter wheat fields (Field 1 and Field 2) in Morocco, monitored during two agricultural seasons 2016-2017 and 2017-2018. Each field is equipped with an eddy covariance station allowing the estimation of ETc every 30 minutes. In addition, a weather station was installed over an alfalfa plot near the study fields. First, the backscattering coefficient and the interferometric coherence ( ρ at VV polarization) are derived from Sentinel-1 data with a 6-day revisit time and a spatial resolution of 10 m. Second, empirical relationships have between established between Kcb, on one hand, and the interferometric coherence and the polarization ratio, on the other hand and the results are also compared to the classical Kcb-NDVI (derived from Sentinel-2) method. The results show that good statistical metrics are obtained between Kcb and NDVI (R=0.77 and RMSE=0.14 for Field 1). Similar results are obtained also using ρ (R=0.76, RMSE=0.18). Finally, the Kcb is estimated from the calibrated relationships on one season and then used to estimate ETc. The results demonstrate reasonable estimates of ETc on Field 1 (R=0.70, RMSE=0.75 mm/day and bias=-0.18 mm/days) using Kcb-ρ. By contrast, a significant overestimations is highlighted both with  (bias=0.73 mm/day) and NDVI (bias=1.46 mm/day) over Field 2. Interestingly, the Kcb-ρ relationship is more consistent in the estimation of ETc when changing from one field to another. These outcomes open new perspectives for the estimation of ETc from radar data as a potential substitute of NDVI in case of persistent cloud cover.

How to cite: Ouaadi, N., Jarlan, L., Khabba, S., Le Page, M., Chakir, A., Er-Raki, S., and Frison, P.-L.: C-band Sentinel-1 data for estimating the basal crop coefficient and evapotranspiration of winter wheat , EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-14819, https://doi.org/10.5194/egusphere-egu23-14819, 2023.

EGU23-15504 | Orals | HS2.1.1

The summer 2022 drought in the Po valley (Italy): a glimpse of the future climate? 

Davide Bonaldo, Debora Bellafiore, Christian Ferrarin, Rossella Ferretti, Antonio Ricchi, Lorenzo Sangelantoni, and Maria Letizia Vitelletti

The Po valley (northern Italy) hosts important economic activities and contributes to a significant fraction of the national agricultural production. On its coastal region (the Po Delta) reclaimed agricultural lands coexist, largely below the mean sea level, with natural areas of outstanding environmental relevance. Besides affecting the socio-economic and ecological dynamics within its basin, the modulation of the hydrological regime of the Po river also plays a major role in controlling the oceanographic processes occurring in the northern Adriatic Sea, from coastal circulation to deep ventilation and thermohaline circulation at the Mediterranean scale. In this framework, the severe drought that affected large areas of Europe in Spring and Summer 2022 hit the Po river system with particular intensity, with heavy impacts on productive activities and extensive saltwater intrusion in the coastal areas.

By means of observed discharge records and precipitation data from reanalysis and climate models, this contribution presents an analysis of the 2022 drought event, investigating its exceptionality in the recent past climate and exploring its possible recurrence in future conditions. Ensemble projections of rainfall regimes on the Po River basin in two climate change scenarios (RCP4.5 and RCP8.5) show that persistent negative rainfall anomalies like the one that characterised the 2022 event will unlikely become typical features of the future climate, but could remarkably increase their frequency. Furthermore, the impacts of these events will be magnified by rising temperatures, enhancing evapotranspiration rates in agriculture and water demand. Particularly in severe climate change scenarios, heavier and more frequent episodes of water shortage, combined with a rising sea level, are expected to intensify the pressure of saltwater intrusion in the coastal areas of the Po Delta, increasing the risk for environmental impoverishment and for loss of agricultural lands.

Besides investigating in a climate change perspective a recent severe event that struck an important economic and ecological region, the present contribution aims at stimulating the development of advanced climate change adaptation strategies in riverine, deltaic and estuarine systems, emphasizing the importance of an integrated source-to-sea approach to this process. 

How to cite: Bonaldo, D., Bellafiore, D., Ferrarin, C., Ferretti, R., Ricchi, A., Sangelantoni, L., and Vitelletti, M. L.: The summer 2022 drought in the Po valley (Italy): a glimpse of the future climate?, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-15504, https://doi.org/10.5194/egusphere-egu23-15504, 2023.

The Versilia coastal plain hosts an important and strategic aquifer for water supply. Like all coastal aquifers, it is particularly vulnerable to the saltwater intrusion, which can be amplified not only by fresh water over-exploitation, but also by the effects of climate change, including the increase of extreme events that are deeply altering the hydrology of the Mediterranean regions. In order to protect this precious resource, both in quantitative and qualitative terms, an adequate knowledge of the aquifer system is necessary through the development of conceptual and mathematical hydrogeological models. Based on integrated multidisciplinary approach the conceptual hydrogeological model was defined using stratigraphic, hydrogeological and geochemical data elaboration. Subsequently, groundwater flow mathematical models were created using the ModFlow code and Groundwater Vistas like graphical interface. The models allowed to better understand this aquifer system and to identify and, where possible to quantify, the main processes and groundwater components involved. The most important feeding groundwater component, both in terms of water quantity and quality, is the fan of the Versilia River, mainly fed by the river itself in the foothill zone. Even if, in the summer season some piezometric depressions, tied to groundwater exploitation, tend to expand and move towards the coast, thus favouring the seawater intrusion process, in general, the Versilia fan component seems at present to be able to guarantee relative protection against marine ingression. However, this precarious balance could be disrupted by the extreme rainy events that frequently occur in the Apuan Alps region. The huge quantity of water that quickly flows by the river up to the sea during extreme events represents a lack of feeding respect to the aquifer, and consequently the mitigation role of the fan component towards seawater intrusion can be significantly weakened. Thanks to the water budget achieved by numerical model and considering real extreme events occurred in the Apuan-Versilian region it was possible to make considerations about possible effects of these climate regimes on the aquifer system. These extreme events as those occurred in the area in the past, and awaited more frequently in the future, represent a concrete threat for the coastal aquifer system that over next decades could suffer more and more seawater intrusion. Given the reliance of local human activities on groundwater, far-sighted actions of water management (e.g. managed aquifer recharge) are recommended for mitigating such as climate effects.

How to cite: Menichini, M. and Doveri, M.: Conceptual and numerical modelling of the Versilia coastal aquifer (NW-Tuscany, Italy) for quantitative evaluations on groundwater components and possible effects of climate extreme events, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-15981, https://doi.org/10.5194/egusphere-egu23-15981, 2023.

EGU23-16445 | ECS | Orals | HS2.1.1

Analysis of the radar temporal coherence at C band over an olive orchard in semi-arid region 

Adnane Chakir, Pierre-louis Frison, Said Khabba, ludovic Villard, Valerie Le-dantec, Nadia Ouaadi, Pascal Fanise, and Lionel Jarlan

In recent decades, climate change has led to a sharp increase in water demand. Particularly in agriculture, this has put a great strain on already scarce water resources, increased the need for irrigation water, and led to overuse of groundwater. Therefore, sustainable management of water resources while maintaining good agricultural yield by monitoring crop water status is necessary for sustainable and rational management of these resources, especially in arid and semi-arid regions. For this purpose, a detailed knowledge of the different processes describing the diurnal water cycle of plants in a large area is essential. However, micrometeorological or physiological experimental measurements and their partitioning are laborious to perform and not very representative of large areas.

In this regard, remote sensing is a particularly suitable tool for monitoring agricultural areas because of its global and repeated observation. Several studies have highlighted the sensitivity of radar data to vegetation water content especially over the rainforest with spatial scatterometers that observe differences between morning and evening acquisitions. On the other hand, in situ radar experiments with high temporal frequency have made it possible to analyze radar responses over tropical and boreal forests.

This study relates to a similar experiment conducted on an olive orchard located in the semi-arid Mediterranean region of Chichaoua in central Morocco. It allows the acquisition of in situ C-band radar measurements in crop fields, which are acquired continuously, from a tower-based radar system, with a time step of 15 minutes.

The temporal evolution of the interferometric coherence r is analyzed on different baselines Dt, ranging from 15 minutes to 30 days, for the main physiological stages of the olive tree. Four different two-month periods, from December 2020 to November 2022, are chosen as the main physiological stages based on field observations.

The obtained results of r, especially at 15-min min-steps, show a global behavior similar to that observed in tropical and boreal forests: high values (r ≈1) are observed during the night (weak wind, vegetation resting), then a decrease/increase during the day mainly anti-symetric to the wind cycle. As over boreal and tropical forest, a decrease in r is observed before the wind picks up, with is time coincident with sap flows and ETR variations, traducing its sensitivity to water plant content.

Results show that over olive orchard, the r diurnal cycle is less marked than over boreal and tropical forests, due to lower ETR rates and certainly due to a significant soil contribution over this less dense vegetation layer. Furthermore, r values decrease when temporal baselines increase, but values are still meaningful for Dt = 6 days (r = 0.3 compared to 0.6 for Dt = 15 min. for the summer period), available with Sentinel-1 missions.

The present study provides particularly interesting results confirming the sensitivity of C-band coherence to vegetation water status, especially in the early morning. Further work needs to be pursued to verify if we are able to detect the water stress of these plants in semi-arid areas such as Chichaoua through coherence.

How to cite: Chakir, A., Frison, P., Khabba, S., Villard, L., Le-dantec, V., Ouaadi, N., Fanise, P., and Jarlan, L.: Analysis of the radar temporal coherence at C band over an olive orchard in semi-arid region, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-16445, https://doi.org/10.5194/egusphere-egu23-16445, 2023.

EGU23-17188 | Orals | HS2.1.1

Water demand versus supply in a Mediterranean Arid Region : current and future challenges 

Hadri Abdessamad, Mohamed Elmehdi Saidi, El Mahdi El Khalki, Brahim Aachrine, Tarik Saouabe, and Abdeslam Ait Elmaki

This research aims at establishing an integrated modelling framework to assess the impact of climate change on water supply and demand across an arid area in the western Haouz plain in Morocco. Five General Circulation Models (GCM) are used to evaluate future water resources availability under Representative Concentration Pathways (RCP4.5 and RCP8.5 emission scenarios). The projected crop water demand and irrigation water demand were analysed using Aquacrop software, taking into account the impact of climate change on both reference evapotranspiration and crop cycle lengths. The future water balance is simulated by means of Water Evaluation And Planning (WEAP) Tool, including several socioeconomic and land use scenarios under RCP4.5 and RCP8.5. The results reveal an important decrease in net precipitation with an average of -36.2% and -50.5% under RCP4.5 and RCP8.5, respectively. In terms of water balance, the “business as usual” scenario would lead to an increasing of unmet water demand of about +22% in the 2050 horizon and to an increased depletion of the water table that could reach 2m/year. Changing water management and use practices remains the only solution to ensure sustainable water use and deal with the projected water scarcity.

How to cite: Abdessamad, H., Elmehdi Saidi, M., El Khalki, E. M., Aachrine, B., Saouabe, T., and Ait Elmaki, A.: Water demand versus supply in a Mediterranean Arid Region : current and future challenges, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-17188, https://doi.org/10.5194/egusphere-egu23-17188, 2023.

EGU23-601 | ECS | PICO | HS2.1.2

Hydrological performance evaluation of temperature reanalysis products for the Ouémé River Basin in West Africa 

Ishita Jalan, Fabian Merk, Ye Tuo, and Markus Disse

West Africa has a complex climate regime. It affects hydrological predictivity in the region where the majority population depends on agriculture. With a warming planet, the challenge is further exacerbated by frequent hydroclimatic extremes. To achieve secured livelihoods and resilience, hydrological understanding is a key. However, there is an elemental challenge of missing measured weather data. Weather variables that are drivers of the water and energy balance are necessary for the setup of robust hydrological models. We focus on the Ouémé River Basin in Benin, which lacks spatially representative in-situ temperature observations. To fill this gap, the study evaluates global earth datasets in the form of reanalysis products that are emerging useful for hydrological modeling. We perform an intercomparison of five temperature reanalysis datasets for the basin using the hydrological model Soil and Water Assessment Tool (SWAT). These datasets are CFSR, CPC, ERA5, EWEMBI, and PGFv3, available at a daily temporal resolution. We test their performance on the simulation of hydrological processes in the Ouémé basin.

To evaluate each temperature data, a multi-site calibration is performed in SWAT using daily discharge time series. Validation is carried out as a two-fold process. The first is point validation performed using discharge data at five gauge sites and the second is spatial validation on the sub-catchment level conducted using satellite-derived actual evapotranspiration (AET) data from GLEAM v3.5b. This multi-gauge and multi-variable approach is used to minimize uncertainties associated with the application of SWAT.

This study is one of a kind for the basin, testing the datasets for their hydrological performance and overcoming a major gap toward achieving robust models. Temperature reanalysis products provide high temporal resolution, long time series, and spatially representative datasets. However, the response to input data errors can vary significantly given the non-linear interaction of parameters in a hydrological model. Therefore, hydrological evaluation is an important step before reanalysis data can be used for modeling and decision-making. We also demonstrate the significance of testing multiple water fluxes to assess the performance of climate datasets. A higher variation in performance for temperature datasets is observed for AET than for the streamflow component. It is an important outcome to determine the most suitable temperature product for the Ouémé basin.

How to cite: Jalan, I., Merk, F., Tuo, Y., and Disse, M.: Hydrological performance evaluation of temperature reanalysis products for the Ouémé River Basin in West Africa, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-601, https://doi.org/10.5194/egusphere-egu23-601, 2023.

EGU23-1113 | ECS | PICO | HS2.1.2

Application of Advanced Wflow_sbm Model with the CMIP6 climate projection for flood prediction in the data-scarce: Lake-Tana Basin, Ethiopia 

Addis Alaminie, Giriraj Amarnath, Suman Padhee, Surajit Ghosh, Seifu Tilahun, Muluneh Mekonnen, Getachew Assefa, Abdulkarim Seid, Fasikaw Zimale, and Mark Jury

Abstract:  Flood-attributed damages to infrastructure and public safety are expected to escalate in the future due to climate change, land use change, and associated hydrologic changes. In recent years, the reliability of flood forecasts has increased due to the availability of meteorological and hydrological data and advancements in flood prediction science. However, there is limited effort to apply emerging advanced hydrological models for flood prediction in poorly gauged watersheds. The overall objective of this study is to demonstrate applicability of climate model products to generate reliable flood predictions for data-limited and flood-prone areas. In this study, the most recent high-resolution climate models of the Coupled Model Intercomparison Project Phase 6 (CMIP6) were evaluated to assess the impacts of projected climate change on the flood-prone areas of the Lake Tana basin, Ethiopia. The ensemble means of the top five CMIP6 climate model forcing data were used to calibrate and validate a free open-source, spatially distributed hydrological model known as Wflow_sbm. Model-independent multi-algorithm optimization and parameter estimation tool is implemented for calibration and validation of Wflow. In terms of simulating runoff and flood events, application of Wflow_sbm to the Lake Tana basin provided promising results. This study serves as a major step towards the development and implementation of climate model product-driven hydrological model to assess flooding damages of future climate projections within the poorly gauged Lake Tana basin.

How to cite: Alaminie, A., Amarnath, G., Padhee, S., Ghosh, S., Tilahun, S., Mekonnen, M., Assefa, G., Seid, A., Zimale, F., and Jury, M.: Application of Advanced Wflow_sbm Model with the CMIP6 climate projection for flood prediction in the data-scarce: Lake-Tana Basin, Ethiopia, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-1113, https://doi.org/10.5194/egusphere-egu23-1113, 2023.

The filling of the Grand Ethiopian Renaissance Dam (GERD) started in 2020, posing additional challenges for downstream water management in Sudan, which is already struggling to cope with the effects of climate change. This is also the case for many transboundary rivers that observe a lack of cooperation and transparency during the filling and operation of new dams. Without information about water supply from neighbouring countries, it is risky to manage downstream dams as usual and operation information is needed to apply modifications. This study aims to test the applicability of using lumped hydrological modelling coupled with remote sensing data in retrieving reservoir filling strategies in regions with limited data availability. Firstly, five rainfall products (namely; ARC2, CHIRPS, ERA5, GPCC, and PERSIANN-CDR) were evaluated against historical measured rainfall at ten stations. Secondly, to account for input uncertainty, the best three performing rainfall products were forced in the conceptual hydrological model HBV-light with potential evapotranspiration and temperature data from ERA5. The model was calibrated during the period 2006 - 2019 and validated during the period 1991 - 1996. Thirdly, the parameter sets that obtained very good performance (NSE > 0.75) were utilized to predict the inflow of GERD during the operation period (2020 - 2022). Then, from the water balance of GERD, the daily storage was estimated and compared with the storage derived from Landsat observations to evaluate the performance of the selected rainfall products. Finally, three years of GERD filling strategies were retrieved using the best-performing simulation of CHIRPS with RMSE of 1.7 billion cubic meters (BCM) and NSE of 0.77 when compared with Landsat-derived reservoir storage. It was found that GERD stored 14% of the monthly inflow of July 2020, 41% of July 2021, and 37% and 32% of July and August 2022, respectively. Annually, GERD retained 5.2% and 7.4% of the annual inflow in the first two filling phases and between 12.9% and 13.7% in the third phase. The results also revealed that the retrieval of filling strategies is more influenced by input uncertainty than parameter uncertainty. The retrieved daily change in GERD storage with the measured outflow to Sudan allowed further interpretation of the downstream impacts of GERD. The findings of this study provide systematic steps to retrieve filling strategies for data-scarce regions, which can serve as a base for future development in the field. Locally, the analysis contributes significantly to the future water management of the Roseires and Sennar dams in Sudan. 

How to cite: Mohammed Ali, A., Melsen, L., and Teuling, R.: Inferring reservoir filling strategies under limited data availability using hydrological modelling and Earth observation: the case of the Grand Ethiopian Renaissance Dam (GERD), EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-2056, https://doi.org/10.5194/egusphere-egu23-2056, 2023.

EGU23-2819 | ECS | PICO | HS2.1.2

Climate change impacts on rainwater productivity across agricultural landscapes of Ethiopia 

Mosisa Tujuba Wakjira, Nadav Peleg, Johan Six, and Peter Molnar

In this study, the spatio-temporal changes in Rainwater Productivity (RP) and its sensitivity to the changes in precipitation and temperature predicted by climate models in various climatic zones across the rainfed agricultural areas of Ethiopia were analyzed. First, the future precipitation, air temperature, and shortwave radiation from multiple GCM projections were downscaled to a 0.05°x0.05° grid resolution, considering three shared socioeconomic pathways (SSP1-2.6, SSP2-4.5, and SSP5-8.5) and three future periods: 2020-2049, 2045-2074, and 2070-2099 using the present climate (1981-2010) as a reference. Next, the reference potential evapotranspiration was computed using the FAO Penman-Monteith and the actual evapotranspiration was simulated using a daily soil water balance model. Then, the relative crop yield (i.e., the ratio of the actual and water-limited potential yield) was determined as a function of the evaporative stress index and crop yield response factor (Ky) for the two growing seasons -- the main (meher) growing season (May-Sep) and the shorter (belg) growing season (Feb-May) for the present and future climates. The computed relative yield was used as a proxy for RP, under the assumption that effective rainfall is the limiting factor for crop yield. Finally, the sensitivity of RP to projected changes in precipitation and temperature was analyzed based on the one-at-a-time (OAT) approach for warmer and drier versus warmer and wetter climate scenarios.

The results show that under the present climate, the median RP (percent of the potential RP) during the Meher and Belg seasons ranges from about 52% and 34% in semi-arid climates to 93% and 45% in humid climates. The projected Meher RP in the future shows either a slight change or a decrease by up to 10% across the majority of the RFA regions under all SSPs and future periods. Conversely, the Belg season RP is likely to increase by up to 15% across the major Belg-producing regions by the end of the century. The observed changes are the combined effects of the nearly consistent but spatially variable increase in precipitation (for example up to 30% under SSP5-8.5 in the 2080s) and rising temperature (up to 5°C under SSP5-8.5 in the 2080s) over the RFA region. The OAT sensitivity analysis reveals that RP under warmer and drier climates is strongly sensitive to precipitation. However, under warmer and wetter conditions the climate sensitivity of RP is determined by the rainfall regime, i.e, in the areas with unimodal rainfall regimes, changes in RP are dominated by the changes in precipitation while in areas with strongly erratic or bimodal rainfall distribution, temperature, or both precipitation and temperature control the changes in RP. Such analyses are useful for assessing the future climate risks to crop yield due to water stress associated with the expected increases in atmospheric evaporative demand, identifying vulnerable areas across the RFA region as well as possibilities for agricultural expansion.      

How to cite: Wakjira, M. T., Peleg, N., Six, J., and Molnar, P.: Climate change impacts on rainwater productivity across agricultural landscapes of Ethiopia, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-2819, https://doi.org/10.5194/egusphere-egu23-2819, 2023.

EGU23-4000 | ECS | PICO | HS2.1.2

Sensitivity of African Easterly Waves to Dust Direct Radiative Forcing 

Hamza Kunhu Bangalath, Jerry Raj, and Georgiy Stenchikov

African Easterly Waves (AEWs) are the most important precipitation-producing dynamic systems in tropical Africa and Atlantic, where dust in the atmosphere is abundant. But the past studies lack consensus on the sign and magnitude of the dust radiative forcing impact on AEWs primarily because of the disagreement in calculating dust solar radiation absorption. The incapability of coarse-resolution models to represent various dust-AEW interactions is another source of uncertainty. The present study uses a high-resolution atmospheric general circulation model, HiRAM, to investigate the sensitivity of AEWs to the dust direct radiative forcing when dust shortwave absorption varies within the observed limits. Global simulations are conducted with the 25 km grid spacing to adequately simulate AEWs and associated circulation features. Four 10-year experiments are conducted: One control experiment without dust and three others with dust assuming dust is an inefficient, standard, and very efficient shortwave absorber. The results show that AEWs are highly sensitive to dust shortwave absorption. As dust shortwave absorption increases, AEW activity intensifies and broadens the wave track shifting it southward. The 6-9 day waves are more sensitive to dust shortwave absorption than the 3-5 day waves, where the response in the former has a stark land-sea contrast. The sensitivity of AEW to dust solar radiation absorption arises from a combination of energy conversion mechanisms. Although baroclinic energy conversion dominates the energy cycle, the responses to dust shortwave heating in barotropic and generation terms are comparable to that in baroclinic conversion.

 

How to cite: Bangalath, H. K., Raj, J., and Stenchikov, G.: Sensitivity of African Easterly Waves to Dust Direct Radiative Forcing, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-4000, https://doi.org/10.5194/egusphere-egu23-4000, 2023.

EGU23-6608 | PICO | HS2.1.2

Drought monitoring over the Kruger National Park (2000-2020) integrating remote sensing data. 

Timothy Dube, Abel Ramoelo, Cletah Shoko, Mazvimavi Dominic, Maria P. Gonzalez-Dugo, Hector Nieto, and Ana Andreu

Semiarid regions shaped as a mosaic of savanna-type rangelands, croplands, and other uses such as livelihoods, or natural reserves, cover large areas in Southern Africa. They constitute an essential example of multiple uses of natural resources, combining a high environmental value with great importance in the rural economy and development. These systems are water-limited and highly sensitive to changes in climate, environmental conditions, and land management practices. Although the vegetation of these areas is adapted to variable climatic conditions and dry periods, the increase in drought intensity, duration, and frequency precipitate their degradation. 

 

In Southern Africa, recurrent droughts have strained rainfed agriculture and pasture production, decimating livestock and wildlife. During 2015 and 2016, South African savannas were subjected to a severe drought associated with a strong El Niño event. Open-source satellite time series provide vital information to assess water availability and long-term drought, to help design early warning and conservation strategies. 

 

In this work, we applied the TSEB (Two Source Energy Balance) model integrating MODIS-derived products (1 km) from 2000 to 2021 over the Kruger National Park (KNP) in South Africa. The model was previously validated over the Skukuza experimental site with good agreement. ET followed precipitation rates, although some years with low precipitation maintained average ET values. This may be caused by the ability of the trees to reach groundwater (deep fractured aquifers and alluvial aquifers can be found in the KNP). During some years (e.g., 2004, 2009), annual total ET was much higher than mean annual values. This may be caused by an extreme annual evaporative atmospheric demand and relatively high precipitation. The anomalies of the ratio of ET to reference ET were used as an indicator of agricultural drought on annual scales, and 2002/2003, 2007/2008 and 2015/2016 years stood out for their negative values. The approach helped to model drought over Kruger Park in the long term, providing an insight into the characteristics of the events.

Acknowledgment: This work has been carried out through the project "DroughT impACt on the vegeTation of South African semIarid mosaiC landscapes: Implications on grass-crop-lands primary production" funded by the European Space Agency in the framework of the "EO AFRICA R&D Facility".

How to cite: Dube, T., Ramoelo, A., Shoko, C., Dominic, M., Gonzalez-Dugo, M. P., Nieto, H., and Andreu, A.: Drought monitoring over the Kruger National Park (2000-2020) integrating remote sensing data., EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-6608, https://doi.org/10.5194/egusphere-egu23-6608, 2023.

EGU23-8955 | ECS | PICO | HS2.1.2

Multiscale water accounting under climate change in a transboundary West African basin 

Moctar Dembélé, Elga Salvadore, Sander Zwart, Natalie Ceperley, Grégoire Mariéthoz, and Bettina Schaefli

Water accounting frameworks assess water availability and consumption of various users and are key tools to inform decision and policy making for integrated water resources management. This study presents a modelling framework that integrates a spatially explicit hydrological model and climate change scenarios with the Water Accounting Plus (WA+) tool to anticipate future water resource challenges and provide mitigation measures. The fully distributed mesoscale Hydrologic Model (mHM), spatially calibrated with multiple satellite remote sensing products, is used to predict water fluxes, stocks and flows in the transboundary Volta River basin (VRB) in West Africa. The mHM model is forced with a large ensemble of climate change projection data from eleven general circulation models (GCMs) downscaled by four regional climate models (RCMs) under the representative concentration pathway RCP8.5, obtained from CORDEX-Africa. Outputs from mHM are used as inputs to the WA+ framework to report on the state and trends of water resources over the historical baseline period 1991-2020 and the near-term future 2021-2050. The basin-scale WA+ reporting is reinforced with a multi-scale summary of water accounts across spatial domains including four climatic zones, four sub-basins and the six riparian countries.

The long-term multi-model ensemble mean of the net inflow to the basin is found to be 419 km3/year with an inter-annual variability of 11%, and is projected to slightly increase in the near-term future (2021-2050), due to the increase in rainfall, thereby highlighting the need for adaptation strategies to optimize the water-energy-food-ecosystem nexus in the VRB.

How to cite: Dembélé, M., Salvadore, E., Zwart, S., Ceperley, N., Mariéthoz, G., and Schaefli, B.: Multiscale water accounting under climate change in a transboundary West African basin, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-8955, https://doi.org/10.5194/egusphere-egu23-8955, 2023.

EGU23-11856 | PICO | HS2.1.2 | Highlight

Droughts influence patterns of human settlements in Africa 

Serena Ceola, Johanna Mård, and Giuliano Di Baldassarre

Droughts are increasing in frequency and intensity in many African countries. Their occurrences severely affect agricultural production and thus potentially contribute to human displacement. Yet, the way in which droughts influence patterns of human settlements remain poorly understood. Here we show that drought occurrences across Africa are often associated with (other things being equal) human displacements towards rivers and cities. Our results show that 73-81% of African countries exhibit larger human mobility towards water bodies and urban areas during drought conditions, as compared to non-drought periods. This may result into increasing floodplain population, and thus into potentially larger flood losses, or overcrowding urban areas. As such, our results shed light on the interplay between hydrologic extremes and society, bolstering the analysis on the spatiotemporal dynamics of drought risks in a warming world.

How to cite: Ceola, S., Mård, J., and Di Baldassarre, G.: Droughts influence patterns of human settlements in Africa, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-11856, https://doi.org/10.5194/egusphere-egu23-11856, 2023.

The study investigates the sensitivity of water resources, droughts and hydropower generation to climate change in the Lake Malawi and Shire River basins, covering three different aspects:

  • Analysis of the variability and trends of meteorological and hydrological droughts based on observational data from 1970 to 2013;
  • Drought analysis for future conditions and investigation of potential changes in water balance and various drought indicators;
  • Hydrological simulation and sensitivity analysis of the Lake Malawi water balance and water level, as well as its discharge and associated hydropower generation in the Shire River.

The key findings of these analyses are:

  • Between 1970 and 2013, meteorological droughts have increased in intensity and duration. This can be attributed to a decrease in precipitation and an increase in temperatures and evaporation.
  • The hydrological system of Lake Malawi reacts to meteorological droughts with a time lag (up to 24 months), so that hydrological droughts can be predicted up to 10 months in advance by meteorological drought parameters. Hydrological droughts are characterized by water levels below 474.1 m asl in Lake Malawi.
  • Despite all the differences and uncertainties in climate projections, they agree that meteorological droughts will continue to increase in the future, in the form of increasing drought intensities DI (+25% to +50% for 2021-2050 and +131% to +388% for 2071-2100) and increasing drought months DM (3-5 and 7-8 more drought months per year, respectively).
  • The water level in Lake Malawi, as a residual of the catchment water balance, is very sensitive to changes in precipitation and evaporation. Outflow from the lake is a direct function of lake water level, and the combination of projected precipitation decline and temperature increase ultimately leads to significantly reduced flow in the Shire River and a decline in annual hydropower production of between 1% and 2.5% (2021-2050) and 5% and 24% (2071-2100). Sometimes, individual projections even suggest that the outflow from Lake Malawi would temporarily dry up and the power supply in the country would be interrupted.

It is shown that failure to meet the 1.5°C global temperature increase target will have a severe impact on droughts and water resources in Malawi. This in turn has implications for hydropower production, as a result of which the achievement of most of the Sustainable Development Goals (SDGs) will be at risk.

How to cite: Bronstert, A., Mtilatila, L., and Vormoor, K.: Impacts of climate change on hydrological extremes and hydropower production in tropical Africa: catchments of Lake Malawi and the Shire River in Malawi, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-12047, https://doi.org/10.5194/egusphere-egu23-12047, 2023.

EGU23-16309 | PICO | HS2.1.2

Approaches to community–scale drought and flood early warning 

Justin Sheffield, John Kimball, Jinyang Du, and Koen Verbist

The African Flood and Drought Monitor (AFDM) is a satellite-model based system for monitoring and forecasting flood and drought conditions for the African continent. It has been running operationally since 2008 in various forms, providing useful information on flood and drought risks to a variety of end-users, as well as information for a wide range of water-related applications, including food and energy security, health risks, and migration. This paper provides an overview of the latest version of the system, which incorporates updated versions of hydrological models and meteorological data at high resolution, as well as the state-of-the-art short-term and seasonal forecast models. We also describe the tailoring of the AFDM to national systems across southern Africa and the process of co-design of these systems with national agencies and end-users. The system has been evaluated on several time scales, historically and for short-term (flood) and seasonal (drought) forecasts. Predictability is discussed with respect to end-users needs, especially at the community scale, and how more recent approaches to predict at the community scale are being incorporated into these monitoring systems, using high-performance computing, machine learning and data assimilation.

How to cite: Sheffield, J., Kimball, J., Du, J., and Verbist, K.: Approaches to community–scale drought and flood early warning, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-16309, https://doi.org/10.5194/egusphere-egu23-16309, 2023.

EGU23-16989 | PICO | HS2.1.2 | Highlight

A new global reference evapotranspiration reanalysis: global opportunities in operational drought monitoring and famine early warning 

Mike Hobbins, Olena Boiko, Candida Dewes, Andrew Hoell, Greg Husak, Harikishan Jayanthi, Tamuka Magadzire, Amy McNally, Daniel Sarmiento, Gabriel Senay, and Will Turner

Data-sparse hydroclimates across the globe are often the most vulnerable to climate shocks and their populations to food insecurity. Drought monitoring and famine early warning in these regions have for too long relied on poor parameterizations of atmospheric evaporative demand (E0)—no less than the demand side of drought and of consumptive use by agriculture—either relying on physically poor process representations of E0 or on climatological mean estimates. However, by exploiting the advent of long-term, spatially distributed, and accurate reanalyses of the land-atmosphere system and its drivers we can put new data to use to save livelihoods and lives by improving drought monitoring, famine early warning, and multi-scale agricultural risk assessment.

Here we describe one such effort—to create a daily, long-term, accurate, global operational dataset of E0. Funded by the Famine Early Warning Systems Network (FEWS NET) and its partners, we have developed a nearly 42-year long, daily, 0.125-degree, global dataset of Penman-Monteith reference evapotranspiration as a fully physical metric of E0. This new E0 dataset is driven by the Modern-Era Retrospective analysis for Research and Applications, Version 2 (MERRA-2)—an accurate, fine-resolution land-surface/atmosphere reanalysis. We verified the accuracy of the dataset against (i) point-estimates of E0 derived by Southern African Science Service Centre for Climate Change and Adaptive Land Management (SASSCAL) initiative in Southern Africa, a region with sparse ground-truth data and significant humanitarian need, and (ii) on a spatially distributed basis against E0 derived from other reanalyses (Global Data Assimilation System and Princeton Global Forcing) that, although global, are otherwise unsuitable for operational food-security decision-making.

We summarize the various uses to which the new E0 dataset is already being put in support of food-security monitoring and decision-making in food-insecure countries within the FEWS NET framework: to provide input data for a global implementation of the Evaporative Demand Drought Index (EDDI), which examines anomalies in E0 to permit early warning and ongoing monitoring of agricultural flash drought and hydrologic drought, both crucial drivers of food insecurity; and to diagnose the anomalies in E0 that lead to or signal drought into the relative contributions from its drivers, examining canonical droughts across Africa (e.g., the 2015 drought in Malawi, and the 2016 Horn of Africa drought, and the current multi-year East African drought). We also present use-cases that verify the operational applicability of the new E0 dataset in long-established drought, famine, crop- and pastoral-stress metrics, and in predictability assessments of drought forecasts. Driven by this new dataset, these analyses should significantly contribute to a more holistic understanding of drought and food-security across the African continent and the rest of the world.

How to cite: Hobbins, M., Boiko, O., Dewes, C., Hoell, A., Husak, G., Jayanthi, H., Magadzire, T., McNally, A., Sarmiento, D., Senay, G., and Turner, W.: A new global reference evapotranspiration reanalysis: global opportunities in operational drought monitoring and famine early warning, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-16989, https://doi.org/10.5194/egusphere-egu23-16989, 2023.

EGU23-17140 | PICO | HS2.1.2

In Situ and Earth Observation-Based Monitoring of Water Availability in Rangeland Areas of the Sahel and East Africa 

Kimberly Slinski, Gabriel Senay, James Rowland, Mike Budde, Shrad Shukla, Amy McNally, Alkhalil Adoum, Erwann Fillol, Bamba Ndiaye, and Cherif Assane Diallo

Rangeland water is critical to food security early warning systems in Africa.  Rangelands feed more than half of Africa’s livestock, providing a source of income to 268 million pastoralists and agropastoralists. Rangeland ponds are a vital source of water for pastoral livestock, directly contributing to household food security and health.  However, rangeland areas of the Sahel and East Africa are water-limited, drought prone, and very food insecure.  In December 2022, the United States Agency for International Development’s (USAID) Famine Early Warning Systems Network (FEWS NET) identified >35 million extremely food insecure people in the countries located in the Sahel and East Africa. 

 

The NASA-funded “Earth Observation-Based Monitoring and Forecasting of Rangeland Water Resources” (Rangelands Monitoring and Forecasting System) project partners with FEWS NET to develop new capabilities for monitoring and forecasting water availability in African rangeland ponds.  FEWS NET partner, the U.S. Geological Survey, maintains the Water Point Viewer (https://earlywarning.usgs.gov/fews/software-tools/25), an interactive map that monitors the relative depth and area of 338 water points across arid and semi-arid regions of the Sahel and East Africa, from Senegal to Somalia.  The Rangelands Monitoring and Forecasting System project aims to significantly expand and improve the existing FEWS NET Water Point Viewer by increasing the locations monitored, developing new time series of water point surface area using high-resolution satellite data, improving overall model physics, and developing new forecasting capabilities.  These advanced data streams aim to improve pastoral resilience to climate shocks by increasing the capacity of stakeholders to plan for and respond to drought emergencies.

 

In this presentation, we introduce the Rangelands Monitoring and Forecasting System project and present first results from the 2022 field season.  During the 2022 West African rainy season, Action Contre la Faim collected water level observations from staff gauges installed in twelve ephemeral ponds located along transhumance corridors in Senegal.  Over the same period, the surface water extent of each pond was estimated using Sentinel 1 synthetic aperture radar, Sentinel 2 multispectral data, and Landsat multispectral data.  Additionally, the FEWS NET Water Point Viewer simulated water levels in nearby ponds.  The observed water levels were compared to the modeled surface water levels and the satellite data-based surface water extents to understand how well the FEWS NET Water Point Viewer and remotely sensed data streams capture the seasonal variation of water availability in the ponds.

 

This presentation: 1) presents the comparison results and discusses the accuracy of the model- and satellite-based estimates of water availability; 2) discusses the limitations of using remotely sensed estimates of water availability in the West Africa Sahelian region; and 3) presents lessons learned from conducting a field campaign in rural areas of West Africa.  The results from the first year of the project will inform the development of the next generation of the FEWS NET Water Point Viewer and new satellite-based remote sensing data streams for monitoring water availability in pastoral regions.

How to cite: Slinski, K., Senay, G., Rowland, J., Budde, M., Shukla, S., McNally, A., Adoum, A., Fillol, E., Ndiaye, B., and Assane Diallo, C.: In Situ and Earth Observation-Based Monitoring of Water Availability in Rangeland Areas of the Sahel and East Africa, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-17140, https://doi.org/10.5194/egusphere-egu23-17140, 2023.

EGU23-583 | ECS | Orals | HS2.1.4 | Highlight

An increase in domestic tap water consumption led to a decline in the groundwater reserves of Delhi 

Ajay Ajay and Prasanta Sanyal

Despite the riparian state of river Yamuna and local groundwater reserves, Delhi depends on other rivers to fulfil the rising demand for drinking water.  In the last ten years, the water demand has increased by 39% (2006-2016). In this study, we have tried to understand the domestic water supply system by studying the spatiotemporal variation in the stable isotopic composition of tap water. The stable water isotopes are powerful tracers of hydrological processes in natural and human-managed systems. There are three primary sources with distinct stable water isotopic composition River Yamuna, Upper Ganga canal, Munak canal and local groundwater reserves; the glacial-fed Himalayan rivers and canals fulfil around 90% of the water demand. Numerous government-operated treatment plants in Delhi purify the water from one of the above sources and supply it to consumers. We collected the water sample at every stage of the water supply, from the primary source to the sink, such as samples of canal or river water, raw water before treatment, filtered water after treatment, storage reservoirs, groundwater samples and finally, the household tap waters. 

Contrary to the river, canal water’s isotopic composition shows no spatial variation. Also, the isotopic composition of raw water is similar to the filtered water, indicating no significant loss due to evaporation or any other hydrological process. However, the isotopic composition of tap water shows considerable variation and deviation from its source value. In most regions, tap water’s isotopic composition is higher than that of source water. In Delhi, among all the other sources, the isotopic composition of surface water is lower than that of groundwater. Thus, only the mixing of groundwater with surface water before supplying it to households can explain the observed large variation in the isotopic composition of tap water. Furthermore, our observation suggests groundwater extraction for domestic purposes has increased from 2019 to 2021. The demand for domestic water per capita is rising with the increase in the population. However, the production of treated water is almost constant and depends upon the raw water availability. The excess extraction of groundwater fulfils the gap between supply and demand. Our study suggests that the surface water (river and canal water), or the number of treatment plants, is insufficient to meet the rising water demand in Delhi, which has led to the overexploitation of limited groundwater reserves in the past few years. Therefore, besides irrigation, the excessive groundwater extraction for domestic purposes results in a drop in the North-west India groundwater table. 



How to cite: Ajay, A. and Sanyal, P.: An increase in domestic tap water consumption led to a decline in the groundwater reserves of Delhi, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-583, https://doi.org/10.5194/egusphere-egu23-583, 2023.

EGU23-775 | ECS | Posters on site | HS2.1.4

Predicting un-impacted flow regime in a Mediterranean catchment with SWAT+ for setting an Environmental Flow 

Marianna Leone, Francesco Gentile, Antonio Lo Porto, Giovanni Francesco Ricci, and Anna Maria De Girolamo

The general aim of this work was to define a methodology for setting the environmental flows (E-Flows) in a temporary river with limited data availability through a case study. In the literature, there are many methods to set up an E-Flow, however, the issue is still an emerging discipline in non-perennial rivers due to the lack of specific guidelines at the European and national level and the limited availability of data (i.e., hydrological/biological).

The study area is the Locone river basin (219 km2) located in southern Italy. The climate is typically Mediterranean. The flow regime shows a pattern of low flow and zero flow in summer. The Locone is classified by the River Basin Authority as a temporary river. Upstream of the dam, streamflow was measured from 1971 to 1983. The main land use is winter wheat (64% of the total area), followed by broad-leaved woods (6.6%) and broad beans (5.4%). The main hydrological pressure in the basin is represented by the Locone dam. It was built in 1986 for agricultural purposes (approximately 5,000 hectares are irrigated) and for a hydroelectric power station (1,693,000 kWh / year).

To compensate for the lack of hydrological and ecological data, which characterizes these types of rivers, the open-source Soil and Water Assessment Tool Plus (SWAT +) model was applied. SWAT + is a completely revised version of the SWAT model, which is a physical scale and watershed model, which operates on a daily time step (Arnold et al., 1998). The model was calibrated (NSE = 0.720; Pbias = -11.514 and R2 = 0.84) and validated (NSE = 0.42; R2 = 0.45; Pbias = -12.5). The flow regime has been characterized under un-impacted conditions over a long period (1971-2020) using hydrological alteration indicators (IHAs) based on modeled daily flows. The E-Flow was set by fixing the variability range of each IHA within the interquartile (25th-75th percentile) by applying the Range of Variability Approach. For the Locone reservoir, the mean monthly flow of water releases, the magnitude, and duration of high and low flows, as well as the timing and frequency of floods and drought conditions were defined.

This work made it possible to test the SWAT+ model in a Mediterranean environment, confirming its potential. The applied method represents a first useful evaluation analysis that should be revised following ecological data monitoring actions to corroborate the eco-hydrological relationships.

How to cite: Leone, M., Gentile, F., Lo Porto, A., Ricci, G. F., and De Girolamo, A. M.: Predicting un-impacted flow regime in a Mediterranean catchment with SWAT+ for setting an Environmental Flow, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-775, https://doi.org/10.5194/egusphere-egu23-775, 2023.

EGU23-778 | ECS | Posters on site | HS2.1.4

Different approaches to model temporary hydrological regimes in a Mediterranean karst basin using the SWAT model. 

Marco Centanni, Giovanni Francesco Ricci, Anna Maria De Girolamo, and Francesco Gentile

In the Mediterranean Region basins are characterized by a specific hydrological regime that generally includes periods of absence of flow and flash flood events. Lithological and geological features are factors that greatly affect the flow regime. In this work, the Soil and Water Assessment Tool (SWAT) model was applied to simulate the Canale d'Aiedda (Apulia, Italy) flow regime, a Mediterranean temporary karst river basin with limited data availability. Different basin delineations and model parameterizations were adopted that include: (i) cut-off of karst areas in GIS (Configuration A); (ii) setting up the basin including the karst areas (Configuration B) and (iii) parameterizing, in the calibration process, the Crack Flow function in the karst sub-basins (Configuration C). The model performed satisfactorily for daily streamflow for configurations B and C and good for A. A better simulated large floods. C was the best solution for monthly flow from May to July. Regarding the water balance, C showed higher surface runoff values and lower total water yield values than A and B. The Crack flow function proved to be a valid option to improve the simulation of hydrological processes in karst areas. Several factors, such as the final aim of the study, data availability, and basin characteristics should be considered in selecting the best model configuration.

How to cite: Centanni, M., Ricci, G. F., De Girolamo, A. M., and Gentile, F.: Different approaches to model temporary hydrological regimes in a Mediterranean karst basin using the SWAT model., EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-778, https://doi.org/10.5194/egusphere-egu23-778, 2023.

EGU23-780 | ECS | Orals | HS2.1.4 | Highlight

The Impact of Meteorological Drought on Vegetation Health in the Middle Euphrates River Basin (Syria) 

Hiba Mohammad, Marco peli, and Stefano Barontini

Syria is now witnessing the dramatic effects of a multiyear drought that has been afflicting the country since 2006. The drought has impacted several regions, but the north-eastern Al Jazira region, corresponding to the Middle Euphrates River basin and considered the Syrian “breadbasket”, has been hammered particularly severely.

With this paper we aim at contributing to the knowledge on the consequences of multiyear meteorological drought on food security in the basin of the middle range of the Euphrates River in Syria.

Annual precipitation data were collected from 11 ground meteorological stations for the period 1983–2020 covering an area of 96800km2. Data were provided by the Syrian Ministry of Agriculture. In addition, the series of two satellite-based indices, namely Vegetation Condition Index (VCI) and Vegetation Health Index (VHI) were collected to analyse the vegetation responses to the meteorological drivers. These indices were downloaded at a resolution of 4-km for the time range 1983-2020, from the Centre for Satellite Applications and Research (STAR) of the National Oceanic and Atmospheric Administration (NOAA). The crop production data, including yields of cotton, wheat, and maize, were collected at provincial level over the period of 1983–2020 from Syria Statistical Yearbook.

Recent changes in meteorological drought features (e.g., frequency and intensity) throughout Syria for the years 1983–2020 were assessed by means of the Standard Precipitation Index (SPI), to characterize the meteorological draughtiness for the Al-Jazira region.

SPI was computed on a 12-month timeline to account for the delayed effect of rainfall deficiency on crop output. Commonly, agricultural droughts are evaluated using drought indices at these long timeframes (e.g., 18 and 24 months) because these longer timescales reflect the accumulated influence of meteorological drought that might alter soil water content and stream flow. The correlation matrices of the series of SPI, averaged at different time scales to focus on the effect of multiyear drought events, with the series of VCI and VHI, will be presented.

This work is preliminary to the GIS application of simplified Benfratello’s water balance method (Barontini et al., 2021) to assess the proneness to water scarcity and the irrigation deficit of different areas of the basin.

References

Barontini, S., Rapuzzi, C., Peli, M., and Ranzi, R.: A GIS based application of Benfratello's method to estimate the irrigation deficit in a semiarid climate, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-12936, https://doi.org/10.5194/egusphere-egu21-12936, 2021.

How to cite: Mohammad, H., peli, M., and Barontini, S.: The Impact of Meteorological Drought on Vegetation Health in the Middle Euphrates River Basin (Syria), EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-780, https://doi.org/10.5194/egusphere-egu23-780, 2023.

EGU23-975 | ECS | Posters on site | HS2.1.4

Evaluation of baseflow processes in the Yellow River Basin, China 

Shixuan Lyu and Junlong Zhang

Yellow River is the mother river of the Chinese nation. It has provided available water resources for more than 5000 years and makes the Yellow River Basin (YRB) a significant grain-producing in China. Recently, promoting the high-quality development of the YRB has been proposed as a Chinese national strategy, highlighting the high status of the YRB in China. However, covering a large area of the arid and semi-arid region, hydrometeorological extremes such as droughts have often occurred in historical periods in the YRB, with prolonged effects on agricultural production. In addition, water conflicts (i.e., water shortage) between human beings’ needs and water resource availability have been much more severe due to population growth and global warming, affecting the ecological health of basins and challenging the lives of riparian residents. Baseflow is a stable flow during the drought season to discharge total streamflow from the groundwater and other delayed sources, which is significant for maintaining the ecological health of river basins and promoting sustainable economic development in arid and semi-arid catchments. Therefore, it is urgent to investigate baseflow characteristics and their determinants for understanding the hydrological processes better and provide scientific foundations for mitigating water shortage problems in the YRB.

Based on that, we collected the daily streamflow records from the main catchments in the YRB. The daily ensembled mean baseflow records derived from Lyne-Hollick, Chapman-Maxwell, Eckhardt and United Kingdom of Institute Hydrology (UKIH) separation algorithms were obtained after the 21st century to reduce simulation uncertainties. Dynamics hydrological signatures were extracted to investigate baseflow spatiotemporal variations and their determinants. Catchments’ physical properties, including topography, vegetation, soil and human activities, were selected. The stepwise model was conducted to see how these catchments’ properties influence the hydrological signatures variability and the ranking of their importance. Our findings showed significant spatial distribution patterns of hydrological signatures in the YRB. Most of them had higher values in upstream and downstream reaches, while low values were in the middle reaches. The magnitude of temporal variation of hydrological signatures was strongly correlated with the catchment topography, vegetation conditions and cropland coverage. It is challenging to discover one single controlling property influencing hydrological signatures for all catchments across the YRB. For most of the hydrological signatures, soil textures, precipitation and vegetation conditions are the most significant influencing factors, indicating the baseflow processes are influenced by a synergistic effect in the YRB.

This study comprehensively investigated the baseflow characteristics in the whole YRB. It can not only provide scientific foundations for water resources management in the YRB but also take an example of how to quantitively evaluate the baseflow characteristics in large semi-arid and arid catchments.

How to cite: Lyu, S. and Zhang, J.: Evaluation of baseflow processes in the Yellow River Basin, China, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-975, https://doi.org/10.5194/egusphere-egu23-975, 2023.

EGU23-1745 | Posters on site | HS2.1.4 | Highlight

Impact of Forestation and Land-use Changes on Desert Climate 

Ambroise Dufour, Suleiman Mostamandi, Kasper Johansen, Oliver Lopez Valencia, and Georgiy Stenchikov

Growing forests is an effective way of removing CO2 from the atmosphere. Forestation projects were started in China, Germany, and the Middle East. Saudi Arabia announced its ambitious “Saudi Green Initiative,” intending to plant ten billion trees. Given the insufficient rainfall to support the initiative, vegetated areas will require irrigation, effectively increasing evaporation. In addition, those areas have a lower albedo than bare land, absorbing more solar radiation. Enhancing precipitation due to the recycling of evaporated water is important as it reduces the amount of freshwater required for irrigation.

In this study, we focus on the regional climate impact of irrigated forested or vegetated areas on temperature and precipitation over the Arabian Peninsula to quantify their effect on livability and evaluate the water recycling potential. First, we studied the climate effect of irrigated farming developing over vast areas in Saudi Arabia since the 1980s. The agricultural areas were mapped using available satellite-based observations from the Landsat platforms, which capture optical and thermal data every 16 days at a resolution of 30 m to 100 m. Second, we projected the climate impact of widespread forestation over the Arabian Peninsula.

The analysis of the long-term precipitation changes caused by irrigated farming is hindered by the lack of in situ observations and the limitations of global-scale observation data sets. Most reanalysis products have contradictory evaporation trends and indicate an overall reduction in rainfall since the 1980s. The recycled precipitation cannot be estimated reliably because of reanalysis increments and background rainfall variability. Presumably, the local increase in rains occurs downstream of the irrigated areas rather than over them. Along with the analysis of observations, we conducted numerical experiments mimicking the effect of irrigated agricultural fields using a non-hydrostatic regional meteorological model (WRF), covering the whole Arabian Peninsula by a 9x9 km2 grid, with 3x3 km2 nesting over the irrigated areas. Irrigation water is accounted for by tagging moisture evaporated from agricultural regions. The amount of tagged water vapor falling as rain represents recycled precipitation. The simulated evaporation and local temperature response strongly depends on the level of irrigation. Large-scale subsidence suppresses the local deep convection over most parts of the Arabian Peninsula. Strong turbulence quickly mixes evaporated water vapor within a six km thick atmospheric boundary layer, preventing precipitation in shallow convection so that the fraction of recycled rainfall appears to be low.

How to cite: Dufour, A., Mostamandi, S., Johansen, K., Lopez Valencia, O., and Stenchikov, G.: Impact of Forestation and Land-use Changes on Desert Climate, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-1745, https://doi.org/10.5194/egusphere-egu23-1745, 2023.

EGU23-1808 | ECS | Posters virtual | HS2.1.4

Assessment of six satellite precipitation products in a Moroccan arid area 

Mariame Rachdane, El Mahdi El Khalki, Mohamed Elmehdi Saidi, Mohamed Nehmadou, Abdellatif Ahbari, and Yves Tramblay

Precipitation is the main component of the hydrological cycle; it is a crucial source of data in hydroclimate applications for water resources management. However, several regions, especially mountainous and arid regions, suffer from limited data from a ground measurement network. Remotely sensed data may provide a viable alternative for these regions. This study aims to evaluate six high spatio-temporal resolution satellite products (GPM-F, GPM-L, GPM-E, CHIRPS, PERSIANN-CCS-CDR and PDIR-Now) in the sub-Saharan regions of Morocco during the period September 2000-August 2020. The record data from 33 rain-gauge stations was used to evaluate these products on two spatial scales (pixel and basin scales) and three temporal scales (daily, monthly and annually), adopting a quantitative and qualitative evaluation. For all examined timescales, the results showed that the GPM-F product performed the best quantitatively, while at the detection capability tested for different threshold and at daily time scale, the GPM near real-time products (GPM-E and GPM-L) were better at detecting more intense rainfall events higher than 40 mm/day. At the daily time scale, GPM-E and GPM-L and, on monthly and annual scales, CHIRPS and PERSIANN-CCS-CDR, provided satisfactory precipitation estimates. Moreover, the evaluation based on the altitudes of rain gauges revealed a bias increasing from low to high altitudes. The findings also highlight that the continental and mountainous basins showed the lowest performance compared to the other locations closer to the Atlantic Ocean. The latitude-based analysis showed a decrease of bias and increase of correlation towards the most arid zones. These results provide valuable information for a scarcely gauged and arid regions, showing that GPM-F could be a valuable alternative to rain gauges.

How to cite: Rachdane, M., El Khalki, E. M., Saidi, M. E., Nehmadou, M., Ahbari, A., and Tramblay, Y.: Assessment of six satellite precipitation products in a Moroccan arid area, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-1808, https://doi.org/10.5194/egusphere-egu23-1808, 2023.

EGU23-2519 | Posters virtual | HS2.1.4

Mean, variance, and trends of Levant precipitation over the past 4500 years from reconstructed Dead Sea levels and stochastic modeling 

Efrat Morin, Tamar Ryb, Ittai Gavriely, and Yehouda Enzel

A novel quantitative assessment of late Holocene precipitation in the Levant is presented, including mean and variance of annual precipitation and their trends. A stochastic framework was utilized and allowed, possibly for the first time, linking high-quality, reconstructed rises/declines in Dead Sea levels with precipitation trends in its watershed. We determined the change in mean annual precipitation for 12 specific intervals over the past 4500 yr, concluding that: (1) the twentieth century was substantially wetter than most of the late Holocene; (2) a representative reference value of mean annual precipitation is 75% of the present-day parameter; (3) during the late Holocene, mean annual precipitation ranged between −17 and +66% of the reference value (−37 to +25% of present-day conditions); (4) the driest intervals were 1500–1200 BC and AD 755–890, and the wettest intervals were 2500–2460 BC, 130–40 BC, AD 350–490, and AD 1770–1940; (5) lake-level rises and declines probably occurred in response to trends in precipitation means and are less likely to occur when precipitation mean is constant; (6) average trends in mean annual precipitation during intervals of ≥200 yr did not exceed 15mm per decade. The precipitation trends probably reflect shifts in eastern Mediterranean cyclone tracks.

How to cite: Morin, E., Ryb, T., Gavriely, I., and Enzel, Y.: Mean, variance, and trends of Levant precipitation over the past 4500 years from reconstructed Dead Sea levels and stochastic modeling, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-2519, https://doi.org/10.5194/egusphere-egu23-2519, 2023.

EGU23-3315 | Orals | HS2.1.4 | Highlight

Is there a turning-point towards improved water and ecological security at the arid Tarim River Basin? 

Weihong Li, Zhi Li, Yaning Chen, and Gonghuan Fang

The arid Tarim River Basin, situated in the Eurasia hinterland, serves as the heart of China’s Silk Road Economic Belt. It covers an area of 1.02 million km2 and is surrounded by the Tienshan Mountains to the north, the Kunlun Mountains to the south and the Pamir to the west. During the past few decades, the contradiction between economic growth and environmental protection is particularly evident. For example, the desert riparian forest vegetation has declined along the lower reaches of the Tarim River.

Under global warming, the climate has experienced significant warming and moistening trend during 1961–2018, and the most dramatic increase has occurred since the mid-1980s. The increased precipitation and temperature and the resulted hydrological and ecological changes lead to a hot debate about the “warm–wet” trend. This study systematically investigated the climate change and their impact on hydrological and ecological processes. The temperature increased at a rate of 0.224 ℃ per decade and an evident jump was detected in 1998. For precipitation, about 72.3% meteorological stations experienced significant increase, with an average increasing rate of 7.47 mm per decade. The changes in climatic factors contribute to the changes in the accumulation and ablation of snow and glaciers, which resulted in changes in hydrological processes. The total lake area in the Tarim River has expanded at a rate of 23.79 km2 per year during 2012–2021. More specially, the lake area of Ayakum Lake (located near the northern boundary of the Tibetan Plateau) has increased by 50% since 1990, with an increment of 111.61 km2 during 1990–2000 and 401.4 km2 during2000–2020. The runoffs of the headwaters (i.e., Kaidu River, Aksu River, Yarkant River and Hotan River) of the Tarim River have also increased by a rate of 2.06×108m3, 2.11×108m3, 1.12×108m3 and 2.56×108m3 per decade, respectively.

However, the changes in ecological systems don’t reflect the wetter trend in the Tarim Basin. The negative effects of climate change on the region’s vulnerable ecology have intensified. The snowfall fraction experienced an overall declining trend, increasing at a rate of 0.6% per decade prior to the mid-1990s, followed by a downward trend at a rate of 0.5% per decade. Potential evaporation decreased at a rate of 41.66mm/10a per decade prior to the mid-1990s, and inversed to increase at a rate of 56.68 mm per decade. Prior to 1998, the normalized difference vegetation index (NDVI) of natural vegetation exhibited an increasing trend at a rate of 0.012 per decade, but from 1999 onwards, the NDVI started decreasing at a rate of 0.005 per decade. The bare soil areas of the Taklamakan Desert boundaries expanded by 7.8 % since 1990. Excessive water use, including unrestrained overpumping of groundwater, causes the loss of groundwater.

This study sheds light on the debate of changes in climate and ecological security under global warming in the endoreic Tarim River Basin. However, more efforts should be made on the continuity of these changes, which is crucial for local development and water and ecological security along the Silk Road.

How to cite: Li, W., Li, Z., Chen, Y., and Fang, G.: Is there a turning-point towards improved water and ecological security at the arid Tarim River Basin?, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-3315, https://doi.org/10.5194/egusphere-egu23-3315, 2023.

EGU23-4167 | ECS | Posters on site | HS2.1.4

Heavy precipitation events where there’s no rain: Saharan rainfall climatology and its relationship with cyclones 

Moshe Armon, Andries Jan de Vries, Francesco Marra, Nadav Peleg, and Heini Wernli

The Sahara is the largest and perhaps the driest desert in the world. This desert however, has not always been this dry. In fact, it is presumed that a few thousand years ago it was much wetter. Moreover, it is projected that, by the end of the 21st century, the Sahara will exhibit the strongest relative increase in precipitation outside the polar regions. To better grasp this information, however, we need to answer some questions: wetter than what? What is the present-day rainfall climatology of the Sahara and what are the synoptic conditions during rainstorms in the desert?

Currently, rainstorms in the Sahara are considered a rare phenomenon. However, rain-bearing cyclones intruding from wetter neighboring regions are possible, and can lead to heavy precipitation events (HPEs) which cause hazardous desert floods. When rainfall occurs, the chances for it to be observed and measured at the ground are close to zero due to the scarcity of rain gauges and the small scale of the precipitation systems. Consequently, the characteristics of rainfall during Saharan rainstorms were seldom analyzed, especially at the scale of the whole desert. In this study, we use high-resolution satellite precipitation estimates (IMERG) and meteorological reanalysis (ERA5) to (a) identify thousands of HPEs that occurred over the Sahara in the past 21 years, (b) characterize rainfall properties during these events, and (c) identify the governing atmospheric conditions on HPE-days, with a focus on surface cyclones.

Our results show that HPEs may occur throughout the entire Sahara. Summer events happen mainly in the southern Sahara. They tend to be short-lived (on average ~12 h) and small in size (~8000 km2), with high-intensity convective rainfall. Conversely, winter HPEs occur primarily in the northern and western parts of the desert, they are longer (~16 h) and larger (15,000 km2) and produce higher rainfall volumes with lower rainfall intensities. When associated with cyclones (29% of events), HPEs exhibit 15% lower rainfall intensities, and 46% higher volumes. This is likely due to a much greater (+64%) areal extent. Our analysis compensates the small number of events at each location with the huge area of the desert, so that a HPE is observed on average every second day. The high-resolution datasets we use enable us to characterize small-size events, with substantial implications for the local scales. Hopefully, such an analysis can serve as a starting point to cope with natural hazards and better understand the future of HPEs in the Sahara.

How to cite: Armon, M., de Vries, A. J., Marra, F., Peleg, N., and Wernli, H.: Heavy precipitation events where there’s no rain: Saharan rainfall climatology and its relationship with cyclones, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-4167, https://doi.org/10.5194/egusphere-egu23-4167, 2023.

EGU23-5987 | ECS | Posters on site | HS2.1.4

Testing hydrological model for Mars using Negev desert based field observations on the Earth. 

Vilmos Steinmann and Ákos Kereszturi

There are many hydrological models for normal terrestrial environments based on precipitation related erosion, but few of them work well in arid and hyper-arid conditions. These extreme arid regions can be good Mars analogue sites to test and model the conditions and laws of precipitation fed runoff and produced erosion on the Red Planet and infer to past periods. The hydrological model we have developed is primarily designed for Martian conditions and has been tested and validated in the Zafit subbasin of the Zin basin of the Negev desert, the eastern part of Israel. The calculated model data were also compared with data from hydrological models and field measurements in the area. Our applied hydrological model without precipitation data is able to estimate the main hydrographic characteristics of the sample area, such as flow discharge, flow velocity, flow depth, and the model is also able to estimate the Formation Timescale (FTS) of some surface features, as well as vertical erosion rates. The model was developed in the open source QGIS software using SAGA and GRASS GIS modules. It uses input variables that can be measured not only under terrestrial conditions but also measured or estimated under Martian conditions, and there are good quality datasets of them. Examples of such variables are the aridity index, which plays an important role in determining the flow discharge, or the density of the rock that makes up the grains, water density, gravity, and grain size classes. The model can be run on any DTM (Digital Terrain Model), the most important constraint being that the linear unit of projection used is defined in SI metres. The hydrological part of the model is complete however under continuous development, and the final model will be complemented by a further developed erosion model to simulate long term surface evolution and change, thus facilitating the understanding of not only terrestrial but also fluvial erosion produced Martian surface changes.

How to cite: Steinmann, V. and Kereszturi, Á.: Testing hydrological model for Mars using Negev desert based field observations on the Earth., EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-5987, https://doi.org/10.5194/egusphere-egu23-5987, 2023.

EGU23-6074 | Orals | HS2.1.4

Atmospheric water capture by desert soils: can we measure it? 

Dilia Kool and Nurit Agam

Atmospheric water, or non-rainfall water inputs (NRWIs) are a critical, albeit largely overlooked, component of the global hydrological cycle. Water vapor adsorption specifically, is not only the least studied form of NRWI but likely the most common one in arid areas.

Lysimeter measurements in the Negev desert during the summers of 2019-2022 indicate that water vapor adsorption in loess soil amounts to at least 33 mm when looked at cumulatively over the summer (0.3-0.5 mm night-1): about ~30% of annual rainfall (116 mm). Given the challenges using lysimeter measurements, attempts to quantify NRWI amounts and duration have generally been limited to short time periods at point or local scales. Determining the true importance of NRWIs in arid and extremely arid environments, which comprise 20% of the terrestrial surface, requires new approaches to measure water content in the 0.5-5% range.

Using weighing lysimeters as a reference, we tested of-the-shelf temperature and relative humidity sensors to assess changes in water content with high temporal resolution over longer periods of time for sand and loess soils. Relative humidity was converted to water potential (Kelvin equation). The water content was then determined using a water retention curve measured with a vapor sorption analyzer. Results showed diurnal patterns in water content consistent with lysimeter measurements. Maximum increase in water content correlated well with lysimeter measured NRWIs. While not all issues are yet resolved, this direction opens possibilities to expand our measurement capacity over longer periods of time and increase the number of measurement locations at relatively low cost. This provides one step forward in trying to understand the magnitude of NRWIs in arid environments across the globe.

How to cite: Kool, D. and Agam, N.: Atmospheric water capture by desert soils: can we measure it?, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-6074, https://doi.org/10.5194/egusphere-egu23-6074, 2023.

EGU23-7066 | ECS | Posters on site | HS2.1.4

Spatial distribution of intermittency in a Brazilian Semiarid river 

Nazaré Suziane Soares, Carlos Alexandre Gomes Costa, Till Francke, Pedro Henrique Augusto Medeiros, Christian Mohr, Wolfgang Schwanghart, and José Carlos De Araújo

Intermittent and ephemeral rivers are characterized by periods of drying and rewetting which occur along different reaches of the channel. Where the channel dries or develops into ponds related to factors such as discharge, topography, geology and riparian vegetation. The aim of this work is to evaluate the spatial patterns and dynamics of intermittency in reaches of a Brazilian semiarid river. Using repeated surveys with unmanned aerial vehicles (UAVs), we characterize its connectivity by identifying locations with different water condition. The Umbuzeiro River (approximately 80 km long; 6.65°S, 40.41°W) is the main river in the Benguê catchment (~1000 km²) that is controlled by the Benguê reservoir, with a storage capacity of 18 hm³. Umbuzeiro is an intermittent/ephemeral river and spatially coherent streamflow occurs mainly in the wettest months of the rain season. We conducted UAV surveys each month from March to June 2022, allowing us to produce detailed hydrological characterizations along different sections of the river. The imagery sets from different UAVs, i.e. DJI Phantom 4 pro and eBee SQ, provided relatable characteristics for a same reach. Visually analysing the reaches, their water condition was determined for smaller subsets, i.e. ponds or dry spots. Observing the temporal and spatial patterns of the presence of water on the riverbed in the different reaches for each survey, we conclude that the patterns are not only dependent on the contributing area of each section, but also on the river’s natural sinuosity, riffle-pool sequences and riparian vegetation. Our results highlight and provide an explanation for the hydrological diversity of semiarid rivers which is important to understand their ecological role and habitat.

How to cite: Soares, N. S., Costa, C. A. G., Francke, T., Medeiros, P. H. A., Mohr, C., Schwanghart, W., and De Araújo, J. C.: Spatial distribution of intermittency in a Brazilian Semiarid river, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-7066, https://doi.org/10.5194/egusphere-egu23-7066, 2023.

EGU23-9376 | ECS | Orals | HS2.1.4

The usage of fog and dew in solar power plants of the Atacama Desert 

Felipe Lobos Roco, Francisco Suarez, Rodrigo Escobar, Pablo Osses, Carla Ramirez, Klaus Keim, Ignacio Aguirre, Francisca Aguirre, Constanza Vargas, Francisco Abarca, and Camilo del Rio

The Atacama desert is one of the most promising places on Earth for developing solar power energy due to its aridity, irradiation, and market conditions. However, the high levels of dust attenuate solar power production. This problem is solved by frequent cleaning of the solar panels, which requires a significant amount of water in one of the driest places in the world. Despite the drought condition, the fog and dew formed at the coastal zone of the desert arise as a complementary water source that can potentially be tapped. In this study, we assess the potential of atmospheric water for usage in four solar power plants. We conduct this assessment by combining a satellite-spatial analysis of fog and low cloud frequency, a thermodynamic vertical characterization of the marine boundary layer, and an observational analysis of fog and dew collection using different instruments. Our results reveal that fog and dew are a regular phenomenon in the solar power plants analyzed, being present between 3% and 20% of the year. Oceanic conditions control such phenomena through the inland advection of the marine boundary layer. This layer interacts with a complex topography characterized by natural corridors that allow fog and low clouds to penetrate farther inland. Our observations show that fog and dew are collected mainly during the night, with average rates between 0.1 and 0.2 L m-2 day-1. Our research confirms that atmospheric water potential vastly exceeds the solar power plant water demand, demonstrating that atmospheric water is a reliable source for the industry.

How to cite: Lobos Roco, F., Suarez, F., Escobar, R., Osses, P., Ramirez, C., Keim, K., Aguirre, I., Aguirre, F., Vargas, C., Abarca, F., and del Rio, C.: The usage of fog and dew in solar power plants of the Atacama Desert, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-9376, https://doi.org/10.5194/egusphere-egu23-9376, 2023.

The Gravity Recovery and Climate Experiment (GRACE) and GRACE-Follow On (GRACE-FO) when combined with traditional data sources (geochronology, geochemistry, hydrology, modelling) can enhance our understanding and monitoring of elements of hydrologic systems including recharge of reservoirs, groundwater flow direction and rates, and the impacts of climate change on watersheds worldwide.  We cite a few examples. Large seasonal fluctuations (peak: Nov./Dec.; trough: July/Aug.) in Lake Nasser's surface water levels are accompanied by an increase in GRACETWS (average: 50 ± 13 mm/yr, up to 77 ± 18 mm/yr) over Lake Nasser in Upper Egypt and by a progression of a front of increasing GRACETWS values (> 50 ± 13 mm) away from the lake reaching distances of up to 700 km some 3 to 5 months following peak lake level periods. Those patterns are consistent with rapid turbulent groundwater flow from Lake Nasser along preferred flow directions (networks of faults and karst topography). The Tigris Euphrates watershed (30 dams) showed an impressive recovery following a prolonged drought (2007–2018; Average Annual Precipitation [AAP]: ~400 km3) by an extreme precipitation event in 2019 (726 km3) with no parallels in the past 100 years. This recovery (113±11 km3) compensated for 50% of the losses endured during drought by impounding a large portion of the runoff within the reservoirs (capacity: 250 km3). The Aswan High Dam, with its storage capacity of 150 km3 represents one of the best-engineered systems that enabled Egypt to ride out droughts and avoid extreme flooding events that affected neighboring Sudan. Additional engineering structures are recommended to take advantage of the excess Lake Nasser waters (35 km3), now residing in the Tushka lakes. In basins lacking artificial reservoirs, a different response to extreme precipitation events is observed from temporal GRACE solutions. Extreme precipitation events (2011-2022) over northern Arabia (PPT: Hail: 8.43 km3; Ad-Dahna: 2.22 km3 and Medina: 3.71 km3) and central Arabia (PPT: Riyadh: 4.66 km3 and Mecca: 0.21 km3) produced an increase in GRACETWS that lasted for a few months only. Cyclones over Oman (2011and 2015; PPT: 6 and 6.6 km3, respectively) had a similar effect. Findings demonstrate that highly engineered watersheds are better prepared to deal with the projected increase in the frequency and intensity of extreme rainfall and drought events in the 21st century.

How to cite: Sultan, M., Abdelmohsen, K., Saleh, H., and Karimi, H.: Recharge from Reservoirs, Groundwater Flow, and Response to Climate Variability in Arid Basins: Revelations from GRACE Observations, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-9959, https://doi.org/10.5194/egusphere-egu23-9959, 2023.

In Mongolia, overuse and degradation of groundwater is a serious issue. The authors have recently applied a process-based eco-hydrology model, NICE (National Integrated Catchment-based Eco-hydrology) to urban and mining hubs to explicitly quantify spatio-temporal variations in water availability (Nakayama et al., 2021a, 2021b). In this study, NICE was scaled up to the total of 29 river basins in the entire country (Ministry of Nature, Environment and Tourism, 2013). The model simulated the effect of past climatic change and human activity on water resources during 1980-2018 there. The model reasonably reproduced observed river discharge with a maximal value during summer rainfall seasons. The simulation also revealed heterogeneous distributions of hydrologic budget and its response to climatic and anthropogenic disturbances. In addition, the authors detected hot spots of groundwater degradation by anthropogenic activity in the national scale. Analysis of relative contribution of environmental factors further clarified the characteristics in these areas and quantified spatio-temporal trends in groundwater level due to the effects of changes in precipitation and various water uses. Generally, the result showed changes in precipitation had a large effect on changes in groundwater levels until 2000. In contrast, the model clarified human activities have recently had a large impact on groundwater level changes (Banerjee et al., 2014). This trend was particularly conspicuous in river basins with urbanization and mining development such as Orkhon, Kharaa, Tuul, Galba, Ongi, Altain Uvur Govi, and Taats River Basins. This methodology is powerful to resolve future competition for water resources in areas with fewer inventory data that could potentially trigger conflicts between urban, mining, industry, herders and local communities.

 

References;

Banerjee, R., et al. 2014. 2030 Mongolia: Targeted Analysis on Water Resources Management Issues, https://www.2030wrg.org/mongolia-targeted-analysis-wrm-issues/.

Ministry of Nature, Environment and Tourism. 2013. Basin Boundary Data in Mongolia, Ulaanbaatar.

Nakayama, T., et al. 2021a. Ecological Modelling, doi:10.1016/j.ecolmodel.2020.109404.

Nakayama, T., et al. 2021b. Ecohydrology & Hydrobiology, doi:10.1016/j.ecohyd.2021.07.006.

How to cite: Nakayama, T.: Impacts of anthropogenic activity and climate change on water resources for the whole of Mongolia by using process-based eco-hydrology model, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-10173, https://doi.org/10.5194/egusphere-egu23-10173, 2023.

EGU23-12017 | ECS | Orals | HS2.1.4

The GW-SW dynamics of a perennial dryland river in the semi-arid region, India 

Anukritika Raj, Vikrant Jain, Vivek Kumar Bind, Virendra Padhya, and Rajendrakumar Dattatraya Deshpande

The Groundwater-Surface water (GW-SW) interaction governed by vertical connectivity, drainage pattern, subsurface lithology, vegetation cover, and land use determines the water availability in semi-arid dryland regions. It plays a crucial role in eco-hydrology, effective water resource management and overall socio-economic development in these marginal environments. Furthermore, the perennial dryland rivers flowing through these semi-arid dryland regions undergo substantial precipitation and flow variability, thus making sustainable water management challenging. Nevertheless, an understanding of the GW-SW dynamics, its spatial variability and the processes influencing the water supply in the semi-arid perennial dryland rivers are still lacking. For this purpose, the stable isotopes of oxygen and hydrogen, in terms of δ18O, δ2H and d-excess parameters of water samples, have been used to assess the GW-SW interaction in the semi-arid perennial Mahi River basin, India. The Mahi River has a length of ~560 km and a drainage basin area of ~34k km2. In total, 53 samples of groundwater and 14 samples of river water were collected during the dry season. In a given river transect, GW samples were collected from both river banks at a distance of around 1 km and 2km, respectively. The result shows changes in GW-SW connectivity at the reach scale. The SW in the downstream and middle reaches (36 to 208km from the river mouth) is characterised by a progressive decrease in δ18O from -1.3 ‰ to -2.6‰. The decrease in the δ18O value in the middle and downstream reaches indicates the mixing of depleted GW into the river. The trend changes in the upstream reaches (208 to 491km), where the SW becomes progressively enriched in δ18O from about -2.1‰ to 0.08‰, with reach scale variability. The upstream reaches also show a decrease in d-excess value from -3.2‰ to -7.2‰, along with the increasing δ18O values suggesting enhanced evaporation of SW during the low flow conditions. The average δ18O of SW in the middle and downstream reach is -1.9 ‰, whereas the average δ18O of the upstream reach is -0.5 ‰. The slope of the GW δ18O-δ2H regression line is lower than that of the Global Meteoric Water Line (GMWL), suggesting that the GW undergoes substantial evaporation. The variability of isotopic values and mixing of GW with SW demonstrates that the river channel shows enhanced vertical connectivity for middle and downstream reaches even during the dry season. However, there is vertical disconnectivity in the upstream reaches. This study highlights the need for different management strategies for various reaches of the spatially variable and dynamic perennial dryland rivers in a semi-arid region.

How to cite: Raj, A., Jain, V., Bind, V. K., Padhya, V., and Deshpande, R. D.: The GW-SW dynamics of a perennial dryland river in the semi-arid region, India, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-12017, https://doi.org/10.5194/egusphere-egu23-12017, 2023.

EGU23-13957 | Posters on site | HS2.1.4

On the Evapotranspiration estimates of two contrasting and Heterogenous Ecosystems in Sardinia 

Roberto Corona, Serena Sirigu, Nicola Montaldo, and Gabriel G. Katul

Sardinia island is a reference for ecohydrological studies on past and future climate change effects, representing typical conditions of the western Mediterranean Sea basin. Ecosystems are heterogenous, and trees optimize the use of water through the root systems, uptaking water from the deep layers.

Two micrometeorological towers have been installed in two different sites under different precipitation conditions. The first is installed in Orroli (annual precipitation of about 600 mm), in a patchy mixture of wild olive trees and C3 herbaceous that grow in a shallow under a rocky layer of basalt, partially fractured (soil depth 15 40 cm), with a tree cover percentage of 33% in the footprint. Instead, the second is in a mountainous forest site of Quercus ilex characterized by steeper slopes and rocky outcrops (mean annual precipitation of about 800 mm), and tree cover percentage of 68% in the footprint. In both sites land surface fluxes and CO2 fluxes are estimated using the eddy correlation technique while soil moisture was estimated with water content reflectometers, and periodically leaf area index (LAI) were estimated.

The following objectives are addressed:1) pointing out the dynamics of land surface fluxes, soil moisture and CO2 for two contrasting sites; 2) assess the impact of vegetation dynamics and type on the CO2 and water balance dynamics; 3) evaluate the soil effect on water and energy budgets.

The Orroli site is more controlled by rainfall seasonality, and vegetation species use the source of water stored in the deep rocky layer to sustain their physiological activity. In the Orroli site we found seasonal dynamics in the CO2 flux and in the evapotranspiration (ET) terms, which are higher when grass and woody vegetation species are present and lower when the grass component dies. Instead, we found a constant flux of ET in the Marganai highlighting the high efficiency of tree species in extract the deep sources of water. ET is higher in the Orroli site if the grass species are present in live form, and then LE is higher in the Marganai forest. The ET of Quercus ilex in the Marganai forest seems being not controlled by surface soil moisture, because the annual precipitation is enough for sustain the transpiration needs of that fraction of tree cover. The results confirm a threshold of 700 mm/year of rain, below which rain can restrict tree cover growth.

How to cite: Corona, R., Sirigu, S., Montaldo, N., and Katul, G. G.: On the Evapotranspiration estimates of two contrasting and Heterogenous Ecosystems in Sardinia, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-13957, https://doi.org/10.5194/egusphere-egu23-13957, 2023.

EGU23-14719 | ECS | Posters on site | HS2.1.4

Water level and stable Isotope based river aquifer interaction in different river styles of a semi-arid river 

Yash Duggad, Vikrant Jain, Virendra Padhya, and Rajendra Deshpande

Understanding the groundwater-surface water (GW-SW) interaction is critical for river management, especially in water-stressed regions such as semi-arid and arid areas. The pattern of GW-SW interaction may vary across variable valley settings, floodplain width and river planform.

This study aims to analyse the pattern of GW-SW interaction in different River Styles reaches. The study is carried out in the Sabarmati River basin in using stable isotopes. Sabarmati River is an intermittent River of 419 km in length that drains a 21,085 km2 area in the semi-arid region of Western India. Representative sites of each River Styles were selected for water level measurement and stable isotope samples. The study was conducted in the post-monsoon period of 2021-22, which represents groundwater contribution to river system after major runoff seasons. Samples at each River Styles reach were collected along a cross-section. 1 river water and up to 4 groundwater samples (2 from each bank) were collected along the transect. A total of 48 samples were collected along 11 such transects. The depth of groundwater and stage of river water at each sample site was also measured.

 

The GW depth and river stage data indicate GW-SW connection for 9 sites (all except 1 are from the upstream region), while was inconclusive for 2 (all in the middle and lower reaches). Stable isotope-based analysis suggests a similar scenario. The upper reaches, which are gaining, have enriched δO18 composition and lower d-excess than the groundwater. The depleted isotopic composition of groundwater indicates faster groundwater recharge from the meteoric water. Such reaches are characterized by boulders and gravel beds. The reach-scale variability of the river from the losing-gaining stream also collaborates with the reach-scale variation of δO18 isotopic values. The losing reach has a depleted δO18 isotopic composition than the groundwater, thus indicating recharge of groundwater from the river water and the impact of evaporation. The integration of the River Styles map and GW interaction study suggests the following – (a) Generally, River Styles that were showing connected and gaining reaches were found to have low sinuosity  (b) River Styles with occasional and discontinuous flood-plains showed an inconclusive result about river aquifer connectivity by both methods (c) For all confined or partly unconfined reaches with bedrock margin-controlled settings, a connected river aquifer system was noted. The study highlights geomorphic control on the important process of GW-SW interaction in a semi-arid river channel.  

Keywords: River style, stable isotope, river-aquifer interaction

How to cite: Duggad, Y., Jain, V., Padhya, V., and Deshpande, R.: Water level and stable Isotope based river aquifer interaction in different river styles of a semi-arid river, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-14719, https://doi.org/10.5194/egusphere-egu23-14719, 2023.

EGU23-15835 | Orals | HS2.1.4 | Highlight

Hydrological processes in the semi-arid small island of Pianosa: a multidisciplinary approach to increase knowledge, awareness and education on a highly climate-sensitive environment (HYDRO-ISLAND project UNESCO’s program) 

Marco Doveri, Matia Menichini, Luca Foresi, Andrea Berton, Letizia Costanza, Ilaria Baneschi, Simone Da Prato, Lorenzo Milaneschi, Brunella Raco, Alessandro Santilano, Sandra Trifirò, Roberto Giannecchini, and Maurizio Burlando

Understanding and quantifying hydrology processes represent a mandatory step in semi-arid and arid regions for defining the vulnerability of these environments to climate change and human pressure, as well as for providing useful data to steer mitigation and resilience strategies. This generally valid concept becomes even more stringent for highly sensitive ecosystems, such as small islands.

It is the case of Pianosa Island (Tuscan Archipelago) that extends a few more than 10 km2 within the Tyrrhenian Sea and it is characterised by a flat morphology (maximum altitude 29 m a.s.l.) and semi-arid climate conditions (550 mm and 17 °C as mean annual precipitation and temperature).

Because of the morphology and the medium-high permeability of superficial bio-calcarenite rocks, superficial water are absent. Nevertheless, the peculiar geological-hydrogeological setting guarantee a storage of groundwater in a phreatic aquifer and semi-confined/confined system, hitherto able to satisfy the local human water demand, mainly tied to seasonal tourism (thousands of visitors/year) and domestic exigencies (less than 30 permanent people). Evapotranspiration represents the most important voice of the water budget, given the windy and relative high temperature conditions.

In the precarious hydro-equilibrium for biosphere and human communities, and considering sea-level rise and climate regime trends that the Mediterranean is experiencing, HYDRO-ISLAND project (UNESCO’s program) intends to deploy a multi-disciplinary approach (geology, hydrogeology, geochemistry, geophysics, remote sensing-smart technology) for better understanding and quantifying the hydrological processes affecting the water availability and for sharing data and transfer knowledge to the community and younger generations, possibly suggesting best practices for water sustainability.

First results pointed out as over the last decade the annual rainfall weakly tended to increase, but at the same time such increasing resulted concentrated in summer and autumn seasons, whereas during winter and spring a decreasing tendency is even observed. This precipitation regime has led to a major rate of evapotranspiration and minor effective infiltration that caused a decreasing of piezometric level over several years. Quantity and chemical-isotopic features of rainfall and effective infiltration water measured/collected by a raingauge and a high precision lysimeter describe the hydrological processes at soil level and characterize the rate and seasonality of groundwater recharge in an experimental site. Using multispectral data by drone, we are trying to extend the experimental site information to a wider area in order to understand the general behaviour at island scale. Measurements, water sampling and analyses for shallow and deep wells, together with the study of geological constraints, are highlighting the distribution and relationship among different groundwater components, including the seawater that intrudes the aquifer from the SE side of the island. Furthermore, the comparative analyses of continuative data monitoring in wells and weather station showed the presence of possible concentrated water infiltration processes during rainfall extreme events that induce a quick response of groundwater systems in terms of water level rise and decrease of electrical conductivity. Thus, elements of vulnerability of the aquifer to pollution are pointed out, as well as the possibility to provide technical solutions for enhancing water infiltration and groundwater availability.             

How to cite: Doveri, M., Menichini, M., Foresi, L., Berton, A., Costanza, L., Baneschi, I., Da Prato, S., Milaneschi, L., Raco, B., Santilano, A., Trifirò, S., Giannecchini, R., and Burlando, M.: Hydrological processes in the semi-arid small island of Pianosa: a multidisciplinary approach to increase knowledge, awareness and education on a highly climate-sensitive environment (HYDRO-ISLAND project UNESCO’s program), EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-15835, https://doi.org/10.5194/egusphere-egu23-15835, 2023.

EGU23-16423 | Posters on site | HS2.1.4

Enhancing Urban Resilience to flooding using Afforestation: the case of Nouakchott city, Mauritania 

Paolo Perona, Emmanuel Dubois, Montana Marshall, Fatimetou Boukhreiss, Saleck Moulaye Ahmed Cherif, Jerôme Chenal, and Charlotte Grossiord

Despite a warm and dry climate, the city of Nouakchott has been facing constant flooding for almost a decade, making part of the city inhabitable and posing long-term health threats. Groundwater levels are relatively constant over the year, except for October, when the groundwater table rises at the end of the rainy season, resulting in an almost doubled flooded area in the city compared to drier periods. Saltwater intrusion maintains a constant level in the water table beneath the city. However, the infiltration of most of Nouakchott’s used water acts as systematic artificial aquifer recharge, thus increasing the risk of groundwater saturation excess and flooding. Hence, in comparison to the driest decade (1971-1980), flooding in the city today cannot only be attributed to the slight increase in precipitation over the last decade. This project hypothesizes that increasing the resilience to urban flooding in the city of Nouakchott can be achieved by using salt-tolerant plants to lower the water table level. This work presents a joined interdisciplinary ecohydrology and plant physiology approach for monitoring and modeling the transpiration and dewatering capacity of different local tree species. The project aims to provide scenarios for an integrated and sustainable afforestation strategy for Nouakchott. In addition to increasing the city’s resilience to flooding, the role that afforestation could play to enhance the provision of sustainable services for the people and the economy (e.g., shade in the streets, potential fruit harvesting and wood market, etc.) will also be discussed. The first field campaign of the project allowed to monitor five observation wells with automatic water depth measurements and 12 sap flow sensors on three tree species. Eventually, to reinforce the relatively scarce groundwater data, a spatiotemporal time series of the city's flooded areas was also reconstructed using remote sensing data, and its reliability to calibrate an eco-hydrogeological model will be discussed.

How to cite: Perona, P., Dubois, E., Marshall, M., Boukhreiss, F., Ahmed Cherif, S. M., Chenal, J., and Grossiord, C.: Enhancing Urban Resilience to flooding using Afforestation: the case of Nouakchott city, Mauritania, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-16423, https://doi.org/10.5194/egusphere-egu23-16423, 2023.

EGU23-17048 | ECS | Orals | HS2.1.4 | Highlight

Response of ecological restoration to rainfall in arid zones 

Yiben Cheng, Xuying Bai, Xiaoxu Ma, Zhiming Xin, Wei Feng, Wenbin Yang, and Jinxin Zhou

Rainfall in arid and semi-arid areas converts faster in the local SPAC system. Deluge in drylands may be an important source of groundwater recharge. We have been conducting a thirty-year observational in the Mu Us sandy land at the northwest China, we use remote sensing imagery to observe changes in the water body area and in situ observations to monitor rainfall infiltration. A total of 30 periods of Landsat remote sensing images were processed using the Google Earth platform to obtain the characteristics of surface water body changes. The results show that there are strong seasonal characteristics in the changes of water bodies area in the Mu Us sandy land, with two peaks in April and August, and the inter-monthly area increases of 44.867 km2 (28.60%) and 47.832 km2 (28.31%) respectively. 379.770 km2 to 275.492 km2, a total reduction of 104.278 km2 (27.46%). Deep soil as a percentage of annual precipitation of woodland, shrubland, grassland, farmland and bare land were 2.88%, 17.36%, 3.64%, 1.21% and 44.30%, respectively. The change in the water body area in the Mu Us sandy land is mainly influenced by three factors, rainfall, vegetation coverage, and human activities, with a correlation coefficient of 0.57 (α=0.05) between rainfall and water body area. The correlation coefficients were 0.79, 0.79 and 0.86 (α=0.05) for the years 1991-1997, 1998-2005 and 2006-2017, respectively; vegetation coverage and water body area were negatively correlated overall in 30 years. The correlation coefficient was 0.57 (α=0.05), indicating that human activities in the Mu Us sandy land have a greater impact and human activities in the sands should be reduced in order to manage the sands.

How to cite: Cheng, Y., Bai, X., Ma, X., Xin, Z., Feng, W., Yang, W., and Zhou, J.: Response of ecological restoration to rainfall in arid zones, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-17048, https://doi.org/10.5194/egusphere-egu23-17048, 2023.

EGU23-496 | ECS | Orals | HS2.1.5

Influence of forest cover on the spatio-temporal heterogeneity of the isotopic composition of precipitation at the small catchment scale 

Pauline Saurat, Pilar Llorens, Loujain Alharfouch, and Jérôme Latron

Forest cover influence the isotopic composition of precipitation before it eventually reaches the ground, especially through rainfall interception processes. Many plot scale recent studies focusing on throughfall and stemflow fluxes have demonstrated the role of forest canopy cover in (mostly) enriching their isotopic signature. However, the common approach in small catchments (even forested ones) remains to sample rainfall only at one single location (generally in an open area), assuming that the spatial variability of the isotopic composition of precipitation is small. Only a handful of studies have focused on the spatial variability of the isotopic composition of precipitation, and very few have included the role of forest cover. Nonetheless, a correct characterization of the isotopic composition of the incoming precipitation is essential in isotope-based catchment hydrology, for example to proceed hydrograph separation, as well as for process understanding or models development.

The aim of this study is to investigate the spatio-temporal variability of the isotopic composition of precipitation in a small Mediterranean catchment (0.6 km²) where forest cover roughly 2/3 of the catchment. Precipitation was sampled at the event scale in 31 locations across the catchment with bulk collectors consisting of plastic funnels (130mm diameter) connected to a 0.5-L plastic bin positioned 100cm above ground before each rain event and collected the day after. The sampling locations were distributed ±80m along 5 elevation lines every 50m (from 1150 to 1350m), 15 in open areas and 16 under forest (i.e., collecting throughfall). The percentage of canopy cover above each sampling location was determined using hemispherical photographs. For all events, rainfall was also measured every 5min at 3 locations with tipping bucket rain gauges and meteorological variables at 2 locations (at the ground level and above the forest canopy). Sampled events were analysed both altogether and separating open areas and under forest locations to determine the factors affecting the spatio-temporal variability of the isotopic composition of precipitation at the catchment scale and their relative influence.

Results show that mean δ18O of the events for the whole catchment varied from -11.96 to -3.6‰ along the year, with a mean coefficient of variation of 39%. Locations under forest were always more enriched than in open areas at the same elevation (+0.67‰ on average). Data analysis using the time stability approach (Vachaud et al., 1985) showed that forest locations had lower persistence of δ18O spatial patterns than open areas, indicating that spatial variability of isotopic composition was less predictable in forest locations compared to open areas. The elevation effect on δ18O, often observed in open area locations, was much less apparent in forest locations, confirming that forest introduced additional complexity on the spatial variability of the isotopic signal. Our findings highlight the actual need of taking into account the effect of both elevation and forest cover to assess a catchment scale representative isotopic composition of precipitation.

How to cite: Saurat, P., Llorens, P., Alharfouch, L., and Latron, J.: Influence of forest cover on the spatio-temporal heterogeneity of the isotopic composition of precipitation at the small catchment scale, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-496, https://doi.org/10.5194/egusphere-egu23-496, 2023.

EGU23-1457 | Posters on site | HS2.1.5

Changes in saturated hydraulic conductivity during forest regrowth over 10 years in the humid tropics 

Sibylle K. Hassler, Jefferson S. Hall, Michiel van Breugel, and Helmut Elsenbeer

Landscapes in the humid tropics are undergoing change in land cover. Besides ongoing deforestation of old-growth forest there is also natural regrowth and active reforestation. These changes in land cover affect soil hydrological properties, eg. saturated hydraulic conductivity (Ks), and thus influence hydrological flow paths. While it has been well documented that removing forest in favour of pasture establishment frequently leads to soil compaction and hence increased occurrence of overland flow and erosion, the effect of reforestation on soil hydraulic properties is less studied, especially not in terms of longer time series of forest regrowth.

We monitored the development of Ks in three reforested catchments in the Panama Canal Watershed, two reforestation trials with native species and teak and a secondary succession, over the course of 10 years. We measured Ks on undisturbed soil cores from the depths of 0-6 and 6-12 cm, applying the constant-head method. We compare the results to a previous study based on a space-for-time substitution in the same area.

Our results show a marked increase in Ks variability in both depths after the first five years of measurement. This points to a non-uniform influence of vegetation development across the catchments. Median Ks values in the topsoil increased at all three reforestation sites over the course of the monitoring period and reached values that considerably exceeded those previously measured in 100 year-old forests in the region, which appears at odds with an assumed continuous increase of Ks with increasing forest age. Further comparisons with soil and vegetation characteristics will be used to explain this apparent contrast.

How to cite: Hassler, S. K., Hall, J. S., van Breugel, M., and Elsenbeer, H.: Changes in saturated hydraulic conductivity during forest regrowth over 10 years in the humid tropics, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-1457, https://doi.org/10.5194/egusphere-egu23-1457, 2023.

EGU23-2052 | Posters virtual | HS2.1.5

The climate-vegetation interactions and subsequent hydrological effect of a subtropical forested watershed, central Taiwan 

Chung-Te Chang, Jun-Yi Lee, Jyh-Min Chiang, Hsueh-Ching Wang, and Jr-Chuan Huang

Vegetation growth is sensitive to climatic variations which has a critical implication for hydrological regimes. However, the intertwined associations of climate-phenology-hydrology have rarely been explored in tropical/subtropical regions particularly. In this study, we synthesize hydroclimate records in forested watershed, central Taiwan for last five decades (1975-2020), and the results indicate that the incidences of meteorological and hydrological droughts are becoming prominent after 2001. We further examine the influences of temperature and precipitation on vegetation growth of watershed scale using EVI (enhanced vegetation index) derived from MODIS (Moderate Resolution Imaging Spectroradiometer) at monthly scale, and explore the effects of seasonal precipitation on the variations of landscape phenology and following watershed streamflow between 2001 and 2020. The EVI and temperature shows a linear relationship (R2 = 0.50, p < 0.001) without time-lag effect, whereas EVI and precipitation exhibits a log-linear relationship with two months lag (R2 = 0.40, p < 0.001), showing the accumulative rainfall during relatively dry period (winter-spring) is crucial for vegetation growth. Structural equation modeling reveals that earlier start of growing season (SOS) caused by relatively high spring rainfall (February-March) leads to longer growing season (LOS) and higher P-Q deficit (precipitation minus runoff) during the growing season. Nevertheless, the large amount of precipitation during growing season has no effect on the end of growing season (EOS), LOS and P-Q deficit. Realizing the vegetation growth responding to climatic variations is necessary for current and future hydrologic regime, especially under changing climate.

How to cite: Chang, C.-T., Lee, J.-Y., Chiang, J.-M., Wang, H.-C., and Huang, J.-C.: The climate-vegetation interactions and subsequent hydrological effect of a subtropical forested watershed, central Taiwan, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-2052, https://doi.org/10.5194/egusphere-egu23-2052, 2023.

EGU23-2852 | Orals | HS2.1.5

Early greenup impact on seasonal streamflow and soil moisture dynamics in humid, temperate forests 

Taehee Hwang, Lawrence Band, Christopher Oishi, and Hojeong Kang

Ongoing warming due to climate change has generally led to lengthened growing seasons and subsequent changes in evapotranspiration (ET) and streamflow seasonality. This has been well studied in seasonally dry, snowmelt dominated watersheds, but not in humid, temperate forested watersheds without significant seasonal snowmelt. In this study, we investigate how seasonal streamflow patterns have responded to variability in vegetation phenology in the southern Appalachians over the last four decades. We characterize seasonal shifts in low-frequency streamflow peaks using 50th percentiles of cumulative daily precipitation, streamflow, and soil moisture measurements, and investigate interactions with remotely sensed, long-term greenup anomalies in the deciduous-dominated forested watersheds. After removing a dominant precipitation control, one-day earlier greenup is associated with about one-day early spring flow peak at the low-elevation deciduous catchment. This indicates that the strong dependency of seasonal flow regimes on precipitation is mediated by warming-induced extended growing season, especially by early greenup. In contrast, we find less significant correlations of the greenup anomalies on flow percentiles of an adjacent evergreen and a high-elevation deciduous catchment. At a plot scale, similar correlations of cumulative soil moisture days were found only at an upslope topographic position, where precipitation also showed tighter coupling with soil moisture patterns than downslope. This indicates that early greenup in deciduous forests leading to early ET increase, in turn results in early soil moisture dry-down patterned by hillslope positions, and earlier seasonal streamflow peaks and subsequent declines. Our study suggests that spring flow peaks are likely to shift earlier by warming-induced early greenup even in snow-free regions, which has great implications for future freshwater availability in the southeastern US.

How to cite: Hwang, T., Band, L., Oishi, C., and Kang, H.: Early greenup impact on seasonal streamflow and soil moisture dynamics in humid, temperate forests, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-2852, https://doi.org/10.5194/egusphere-egu23-2852, 2023.

EGU23-2853 | ECS | Posters on site | HS2.1.5

Deforestation alters dissolved organic carbon and sulfate dynamics in a mountainous head water catchment—A wavelet analysis 

Qiqi Wang, Yuquan Qu, Kerri-Leigh Robinson, Heye Bogena, Alexander Graf, Harry Vereecken, Albert Tietema, and Roland Bol

Deforestation has a wide range of effects on hydrological and geochemical processes. Dissolved organic carbon (DOC) dynamics, a sensitive environmental change indicator, is expected to be affected by deforestation, with changes in atmospheric sulfur (S) deposition compounding this. However, how precisely anthropogenic disturbance (deforestation) under a declining atmospheric S input scenario affects the underlying spatiotemporal dynamics and relationships of river DOC and sulfate with hydro-climatological variables e.g., stream water temperature, runoff, pH, total dissolved iron (Fetot), and calcium (Ca2+) remains unclear. We, therefore, examined this issue within the TERENO Wüstebach catchment (Eifel, Germany), where partial deforestation had taken place in 2013. Wavelet transform coherence (WTC) analysis was applied based on a 10-year time series (2010–2020) from three sampling stations, whose (sub) catchment areas have different proportions of deforested area (W10: 31%, W14: 25%, W17: 3%). We found that water temperature and DOC, sulfate, and Fetot concentrations showed distinct seasonal patterns, with DOC averaging concentrations ranging from 2.23 (W17) to 4.56 (W10) mg L-1 and sulfate concentration ranging from 8.04 (W10) to 10.58 (W17) mg L-1. After clear-cut, DOC significantly increased by 59, 58% in the mainstream (W10, W14), but only 26% in the reference stream. WTC results indicated that DOC was negatively correlated with runoff and sulfate, but positively correlated with temperature, Ca2+, and Fetot. The negative correlation between DOC with runoff and sulfate was apparent over the whole examined 10-year period in W17 but did end in W10 and W14 after the deforestation. Sulfate was highly correlated with stream water temperature, runoff, and Fetot in W10 and W14 and with a longer lag time than W17. Additionally, pH was stronger correlated (higher R2) with sulfate and DOC in W17 than in W10 and W14. In conclusion, WTC analysis indicates that within this low mountainous forest catchment deforestation levels over 25% (W10 and W14) affected the coupling of S and C cycling substantially more strongly than “natural” environmental changes as observed in W17.

How to cite: Wang, Q., Qu, Y., Robinson, K.-L., Bogena, H., Graf, A., Vereecken, H., Tietema, A., and Bol, R.: Deforestation alters dissolved organic carbon and sulfate dynamics in a mountainous head water catchment—A wavelet analysis, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-2853, https://doi.org/10.5194/egusphere-egu23-2853, 2023.

EGU23-3830 | ECS | Posters on site | HS2.1.5

Soil moisture and temperature dynamics in juvenile and mature forest as a result of tree growth, hydrometeorological forcings, and drought. 

Andrea Rabbai, Doris E. Wendt, Giulio Curioni, Susan E. Quick, A. Robert MacKenzie, David M. Hannah, Nicholas Kettridge, Sami Ullah, Kris M. Hart, and Stefan Krause

Afforestation, as one of the major drivers of land cover change, has the potential to provide a wide range of ecosystem services (ES). Aside from carbon sequestration, it can improve hydrological regulation by increasing soil water storage capacity and reducing surface water runoff.  However, afforested areas are rarely studied at the appropriate time scale to determine when changes in soil hydrological processes occur as the forest grows. This study investigates the seasonal soil moisture and temperature dynamics, as well as the event-based responses to precipitation events and dry periods between a mature and juvenile forest ecosystem over a 5-year time period. Generally, soil moisture was higher in the juvenile forest than in the mature forest, indicating less physiological water demand. However, following the 2018 drought, soil moisture dynamics in the growing juvenile plantation began to match those of the mature forest, owing to canopy development and possibly also to internal resilience mechanisms of the young forest to external perturbations. On the other hand, soil temperature dynamics in the juvenile plantation followed air temperature patterns closely, indicating lower thermal regulation capacity compared to the mature forest. While our findings reveal that an aggrading juvenile plantation achieves mature forest soil moisture dynamics at an early stage, well before maturity, this was not the case for soil temperature. Our results shed light on long-term trends of seasonal and event-based responses of soil moisture and temperatures in different-aged forest systems, which can be used to inform future assessments of hydrological and ecosystem responses to disturbances and forest management.

How to cite: Rabbai, A., Wendt, D. E., Curioni, G., Quick, S. E., MacKenzie, A. R., Hannah, D. M., Kettridge, N., Ullah, S., Hart, K. M., and Krause, S.: Soil moisture and temperature dynamics in juvenile and mature forest as a result of tree growth, hydrometeorological forcings, and drought., EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-3830, https://doi.org/10.5194/egusphere-egu23-3830, 2023.

EGU23-4325 | ECS | Posters on site | HS2.1.5 | Highlight

Estimation of rainfall interception from merged drone and terrestrial LiDAR data by modeling 3D canopy structure in plantation forest 

Yupan Zhang, Yuichi Onda, Yiliu Tan, Hangkai You, Thuy Linh Pham, Asahi Hashimoto, Chenwei Chiu, Takashi Gomi, and Shiori Takamura

The multidimensional arrangement of upper canopy features is a physical driver of energy and water balance under various canopies, and standard modeling approaches integrate leaf area index (LAI) and canopy closure (CC) to describe canopies. However, it is unclear how the canopy affects the component and interception of rainfall within the forest system. We generated multi-layered forest point clouds from trunk to canopy using fusion of drone and terrestrial LiDAR data then classified wood and foliage elements using a clustering algorithm to build a high precision physical model for describing throughfall, stemflow and interception. The experiment was conducted in the thinning plantation forest located in Tochigi prefecture, Japan. Rainfall observation for the three components is important for model development. Throughfall was computed from 20 rain gauges distributed on a grid under the forest canopy, 3 stemflow collectors was set up around the tree trunks connected to a bucket with water level sensor. We developed a capacity model to describe canopy saturation with foliage points, a voxel-based method was used to create 3D representations of forest canopies, and an analysis of these point-derived canopy structures and volume were performed to assess the canopy's capacity to contain rainfall. For stemflow modeling, we use a runoff model to simulate the additional rainfall accumulates to the tree trunk through branches when the tree canopy is saturated. Preliminary simulation results show that: (1) fusion and registration of drone and terrestrial LiDAR data can greatly improve the point cloud accuracy and enrich the information contents such as coordinate geo-reference and filling of missing structures; (2) a strong correlation between the rainfall observed canopy interception results and the estimated canopy volume, and the volume-based interception prediction model has a high accuracy, with an R2 from 0.84 to 0.91 compared to past observations. (3) stemflow is related to the projected volume of the canopy and the proportion of wooden structure point clouds, and as the runoff path increases, there is a greater probability that oversaturated precipitation will concentrate on the trunk rather than drip off. High accuracy physical model of tree canopy can well describe the interactions between the rainfall to canopy and illustrate the mechanism.

 

How to cite: Zhang, Y., Onda, Y., Tan, Y., You, H., Pham, T. L., Hashimoto, A., Chiu, C., Gomi, T., and Takamura, S.: Estimation of rainfall interception from merged drone and terrestrial LiDAR data by modeling 3D canopy structure in plantation forest, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-4325, https://doi.org/10.5194/egusphere-egu23-4325, 2023.

EGU23-6746 | Orals | HS2.1.5

Modeling interactions of water fluxes with species and structural diversity in temperate forests 

Friedrich J. Bohn, Sabine Attinger, Charlotte Kihm, and Anke Hildebradt

Ecosystem functions of temperate forests are expected to be severely impacted by future climate change - particularly hydro-meteorological extremes (heavy precipitation events, droughts, and heat waves) that will increase in frequency, duration, magnitude, and extent. Previous studies have shown that both structural and tree species diversity may act as buffers against the impacts of climate extremes.

To better understand the influence of structural and tree species diversity, we use two models to analyze the influence of species and structural diversity on hydrologic dynamics during recent drought events. The well-equipped test sites are located in central Germany and represent typical forests in this area. One model is the individual forest gap model FORMIND. Using a newly developed technique, it allows us to analyze local heterogeneous patterns on a 2 meter scale of carbon and water cycling, flow, and water stress, and their relationship to structural and species diversity. The second model is mHM, a mesoscale hydrological model. We parameterize mHM for two catchments in central Germany (Nägelstedt and Upper Saale). We further analyze the relevance of local heterogeneity in structural and species diversity and the resulting local heterogeneity in water fluxes on the fluxes at the mesoscale.

This two-model and interdisciplinary workflow allows us to consider various soil-plant-atmosphere interactions in drought disturbed ecohydrological systems

How to cite: Bohn, F. J., Attinger, S., Kihm, C., and Hildebradt, A.: Modeling interactions of water fluxes with species and structural diversity in temperate forests, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-6746, https://doi.org/10.5194/egusphere-egu23-6746, 2023.

EGU23-8182 | Posters on site | HS2.1.5

Climate and land use induced changes in evapotranspiration - experimental evidence from a forested catchment in Germany 

Thomas Pluntke, Christian Bernhofer, Thomas Grünwald, Maik Renner, and Heiko Prasse

Climate changes are expected to trigger changes in all water budget components at any scale. For Central Europe, higher evapotranspiration (ET) rates are already observed, other factors like land use or land cover characteristics change in parallel, but experimental evidence of the interdcations is limited, as it requires challenging long-term measurements. We take advantage of the well-documented hydro-meteorological dataset from the forested research catchment Wernersbach in Saxony, Germany, covering 52 years between 1968 and 2019 (Pluntke & Bernhofer et al., 2023).

We analyzed hydro-climatological time-series for linear trends and for breakpoints. Significant positive trends were found for global radiation, mean air temperature and grass-reference evaporation, as well as for the difference between catchment precipitation and runoff (P-R; hydrological estimate of ET). Precipitation increased and runoff decreased over the 52 years, but not significantly.

Air temperature and global radiation show significant breakpoints around 1988 and 1996, respectively, with below average conditions before and above average conditions after the breakpoints. Temperature change is associated with global warming, and possibly with the independent regional effect of air pollution. Since the 1960s, large sulphur dioxide emissions from fossil fuel burning led to a high aerosol density in the troposphere reducing solar radiation over most of Europe and North America. While this effect was reduced by filtering the emissions elsewhere in the early 1980s, it continued in neighboring parts of today’s Germany, Poland, and Czech Republic until the early 1990s. Breakpoint of grass reference evaporation coincides with air temperature (1988), and the breakpoint of P-R is a few years later.

We attributed changes in ET to changes in land use and climate by applying an adapted Budyko framework and enabled insights into their interactions. The sulphur dioxide emissions triggered widespread forest dieback in regions over 600 m in Saxony. Consequences were decreasing ET in the 1970s/1980s. The Wernersbach catchment (390 m) shows a similar tendency (not significant). Since the 1990s, both climate (increasing atmospheric demand) and land use (healthier forest stands and improved management practices) led to an increase of ET. In 2010s, climate induced damages of forest stands (due to droughts, storms, snow load, and bark beetle infestations) led to a drastic decrease of ET in Wernersbach despite favorable climatic conditions for ET. Since the intensity and frequency of such extreme events are likely part of climate change, they may cause greater regional changes in the water balance than direct effects of climate change, and may cause lasting damage to Ecosystem Services of forests, like flood mitigation, or carbon sequestration.

Our results show the need for climate adaptation measures in forests, such as the establishment of a more site-specific mixed forest, and a sustainable  forest management.

 

References

Pluntke T. & Bernhofer C., Grünwald T., Renner M., Prasse H.: Long-term climatological and ecohydrological analysis of a paired catchment – flux tower observatory near Dresden (Germany). Is there evidence of climate change in local evapotranspiration? J Hydrol 617 (2023), https://doi.org/10.1016/j.jhydrol.2022.128873

How to cite: Pluntke, T., Bernhofer, C., Grünwald, T., Renner, M., and Prasse, H.: Climate and land use induced changes in evapotranspiration - experimental evidence from a forested catchment in Germany, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-8182, https://doi.org/10.5194/egusphere-egu23-8182, 2023.

Throughout the Caribbean, hillside quarrying has become a common practice. While these activities remove large sections of the critical soil zone, very little work has been done on how hillside quarrying impacts rainfall runoff response and catchment water storage. We hypothesised that the removal of the critical soil zone during hillside quarrying will increase the timing and magnitude of streamflow response to storm events due to its close proximity to the river, while also reducing the overall storage of the watershed. The aim of this study is to understand the landuse impacts on rainfall runoff response and catchment storage. A paired catchment study between the 3.6 km2 Acono (forested) and the adjacent 3.6 km2 Don Juan (quarried) watersheds in Trinidad and Tobago was conducted using a hydrometric and geochemical approach. Direct measurements of rainfall and streamflow and bi-weekly water sample collections for geochemistry and stable isotopes of 18O and 2H from rainfall, baseflow, soils, springs and groundwater were done. Fraction of young water (Fyw) an inverse transit time proxy was computed along with the mean transit time distributions (MTTDs) by sine wave fitting were used as important descriptors of runoff generation and the catchment storage. The quarried watershed had higher streamflow levels during the wet season than the forested watershed. However, during the dry season there is a reversal.. The quarried watershed responded faster to rainfall events with a lag time between 1–3 hours with a higher peak rate of streamflow versus a lag time of 2-4 hours in the forested watershed with a lower peak rate of flow. In the upper quarried watershed 18.4 % of the stream water were younger than 0.46 years and 20.3% were younger than 0.55 years in the lower portion of the catchment. In the upper forested catchment 5.2 % of the stream water was younger than 2.71 years whereas 4.7% of the stream water was younger than 3.04 years in the lower catchment. The data suggest that the quarry leads to the faster delivery of water during storm events while also reducing the overall storage in the catchment. With an anticipated increase in hillside quarrying, this study provides important information for land use and water resource managers.

How to cite: Farrick, K. and Mathura, N.: Hillside Quarry Impacts on Streamflow and Stormflow response in a Tropical Watershed:  A Geochemical and Hydrometric Investigation, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-9930, https://doi.org/10.5194/egusphere-egu23-9930, 2023.

EGU23-10827 | ECS | Orals | HS2.1.5

Dynamic processes require appropriate methods to capture them: Why in-situ water stable isotope monitoring needs to become a standard method in forest hydrological research 

Matthias Beyer, Kathrin Kuehnhammer, Joost van Haren, Angelika Kuebert, Christian Birkel, Ricardo Sanchez-Murillo, and John Marshall

As a consequence of global change, forests worldwide are undergoing a restructuring process. The expectations for forests of the future are ambitious: Providing resilient forest ecosystems that capture large amounts of carbon but also provide stable groundwater recharge rates. To balance the interests of both forestry and water management authorities, scientists and practitioners need to be able to investigate and predict which forest types and combinations of tree species are most likely to fulfill these needs.

Methods based on the analysis water stable isotopes have been used extensively for studying water uptake depths of vegetation, groundwater recharge, transit times, and water sources in general. Despite being arguably the superior tool when not only amounts but also knowledge of the sources of an (eco-)hydrological flux are needed, the highly dynamic nature of water transport processes within the soil-plant-atmosphere continuum (SPAC) could hardly be captured in the past. With the advent of  laser spectroscopy in the last decade, we are now able to measure water stable isotopes continuously and in all compartments of the SPAC.

In this keynote, we present and review the most recent advances (2016-now) of combined soil and plant in-situ water isotope measurements carried out in different ecosystems worldwide. We then critically discuss the gain in process-understanding of in-situ monitoring approaches and demonstrate how in-situ methods could be integrated with traditional and novel methods to advance forest hydrology.

In-situ and semi-in-situ (i.e., sampling of water vapor) water stable isotope methods have been greatly improved within the last five years. Initial disadvantages (e.g., comparability to traditional methods, complicated & laborious setup & maintenance, expensive) have been carefully addressed, and improvements have been implemented. Recent research has proven that i.) highly dynamic and heterogenous processes (e.g., stem flow, groundwater recharge through preferential pathways, change of uptake depths in response to rainfall/drought, disentangling water use of different tree species in mixed forests) can be captured exceptionally well using in-situ isotope methods; ii.) water-vapor equilibration methods represent the isotope composition of mobile water better compared to destructive methods, and iii.) using continuous water isotope data reduces parameter uncertainties in SPAC modeling.

In summary, we state that the benefits of using in-situ or semi in-situ techniques outweigh the disadvantages by far and strongly encourage the water stable isotope community to integrate them regularly into studies of dynamic soil-plant-atmosphere feedbacks.

How to cite: Beyer, M., Kuehnhammer, K., van Haren, J., Kuebert, A., Birkel, C., Sanchez-Murillo, R., and Marshall, J.: Dynamic processes require appropriate methods to capture them: Why in-situ water stable isotope monitoring needs to become a standard method in forest hydrological research, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-10827, https://doi.org/10.5194/egusphere-egu23-10827, 2023.

EGU23-12766 | ECS | Posters on site | HS2.1.5

DOC mobilisation from forest soils governed by intermittent hydrological connectivity of subsurface water pools 

Sean Adam, Maximilian Lau, and Conrad Jackisch

Climate change in combination with forest management practices is leading to increased DOC release from a forested reservoir catchment in the western Ore Mountains in Germany. The most significant sources of DOC loadings are likely several disturbed patches of former peatland in the catchment. We suspect that the soil water availability and subsequent variable hydrological connectivity of water pools in the shallow subsurface could be major factors for DOC mobilisation impeding the drinking water production in the region.

We present data from almost one year of intensive monitoring in two small catchments (1 ha) located on i) a shallow histosol with a highly compacted mineral subsoil and ii) a regolithic cambisol. Catchment drainage was constantly observed for water levels and in situ spectroscopy to infer discharge rates and DOC concentrations. Soil moisture and temperature, surface temperature and irradiation were continuously measured along the slope gradient. During monthly campaigns in the vegetation period, pore water samples were taken from high and low points of 15 m grid cells spanning the catchments.

In our poster, we would like to discuss our findings that pore water availability is non-uniformly distributed suggesting discrete subsurface flow paths in the catchments. In low moisture conditions, subsurface water pools can be isolated from the pore water network. We argue that disconnected pools accumulate DOC during low moisture conditions, which is then released when the pools are reconnected during strong precipitation events.

How to cite: Adam, S., Lau, M., and Jackisch, C.: DOC mobilisation from forest soils governed by intermittent hydrological connectivity of subsurface water pools, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-12766, https://doi.org/10.5194/egusphere-egu23-12766, 2023.

EGU23-12770 | Posters on site | HS2.1.5

Soil moisture regime under different forest types 

Václav Šípek, Nikol Zelíková, Lukáš Vlček, Jitka Toušková, and Miroslav Tesař

An understanding of the spatial and temporal variation of soil moisture is essential for studying other hydrological, biological, or chemical soil processes, such as water movement, microbial activity, and biogeochemical cycling. The study focuses on the description of soil water dynamics at several sites with different types of forests and their health status. Specifically, the results are based on the thorough description of the soil water regime under spruce forest in two mountainous plots. At one plot the measurements are supplemented with site influenced by bark beetle attack and at another site the comparison with beech forest. The analysis was based on soil water regime measurements from several vegetation seasons (comprising wet and dry years). We investigated both column average soil water content and also its vertical distribution. The water balance of the soil column was studied by the bucket-type soil water balance model.

It was shown that the forest type is an important factor controlling the rate of evapotranspiration which in turn influences the soil water regime, especially in dry periods. In wet periods, the differences among particular sites were negligible. In dry periods, the soil was slightly wetter in the site affected by the bark beetle outbreak in the surface soil layer and drier in the deeper soil layer. Similarly, the beech and spruce forest differences were most pronounced in dry periods. In this case, the beech forest was more efficient in terms of evapotranspiration water consumption which resulted in drier soil compared to spruce covered plot. In the spruce site, the soil was regularly drier only at the beginning of the season which was given by different interception rates during winter. 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 Technological Agency of the Czech Republic (SS05010124), SoilWater project (EIG CONCERT-Japan), and the institutional support of the Czech Academy of Sciences, Czech Republic (RVO: 67985874).

How to cite: Šípek, V., Zelíková, N., Vlček, L., Toušková, J., and Tesař, M.: Soil moisture regime under different forest types, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-12770, https://doi.org/10.5194/egusphere-egu23-12770, 2023.

EGU23-13089 | ECS | Orals | HS2.1.5 | Highlight

Large-scale shifts in transpiration dynamics following bark beetle infestation: Stomatal conductance responses 

Ye Su, Meijun Li, Wei Shao, and Jerker Jarsjö

Tree mortality triggered by bark beetle infestation can significantly affect terrestrial carbon and water balances. However, how to improve the parameterization of the stomatal conductance to express the dynamics of ecosystem disturbance remains unclear. A subalpine forest located in the Rocky Mountains experienced a severe bark beetle outbreak in 2008, which provided a unique opportunity to investigate carbon and water flux changes covering the periods of pre-infestation (2005-2007), infestation (2008-2009), and post-infestation (2010-2014). Affected by bark beetle infestation, the stomatal conductance during the summer season (July and August) significantly reduced from 0.0018 m/s in the pre-infestation period to 0.0011 m/s in the infestation period. The decrease in stomatal conductance was not solely caused by the decrease of LAI, but also related to variation in parameter g1 in three commonly-used models of Ball-Barry, Leuning, and Medlyn. The parameter g1 was related to water use efficiency (WUE), and WUE values increased in the infestation period and decreased in the post-infestation period providing evidence that the physiological behavior was significantly changed due to bark beetle infestation. As for the simulation of transpiration, the fitted parameter significantly improved the accuracy in comparison with recommended parameterization. With the inclusion of temporally varied stomatal conductance, estimated transpiration during the infestation period and post-infestation period was improved by 4.3%~13.6% in comparison with the unvaried parameterization fitted in the pre-infestation period. Accounting for the temporally varied stomatal conductance parameters in response to disturbed environments may improve the description of stomatal conductance leading to better model performance in estimated water and carbon balances.

How to cite: Su, Y., Li, M., Shao, W., and Jarsjö, J.: Large-scale shifts in transpiration dynamics following bark beetle infestation: Stomatal conductance responses, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-13089, https://doi.org/10.5194/egusphere-egu23-13089, 2023.

EGU23-13837 | ECS | Posters on site | HS2.1.5

Forest-floor litter and deadwood cycle significant amounts precipitation 

Marius G. Floriancic, Scott T. Allen, Raphael Meier, Lucas Truniger, James W. Kirchner, and Peter Molnar

Forests modulate precipitation and evapotranspiration fluxes. One important – yet often overlooked - component in the forest water cycle is the forest-floor litter layer. Leaves and deadwood retain significant amounts of annual precipitation and enhance subcanopy humidity. At the “Waldlabor Zurich” ecohydrology field site we conducted numerous experiments to quantify the water fluxes from and to the forest-floor litter layer. We estimated the total retention capacities of needle, broadleaf and deadwood litter, assessed the litter water content before and after precipitation events, and measured soil moisture in litter-covered and litter-free plots. We used micro lysimeters to estimate evaporation from the litter layer and measured subcanopy humidity and temperature at different heights above the forest floor to assess the effect of evaporation on subcanopy microclimate.

Storage capacities of needle litter and broadleaf litter averaged 3.1 and 1.9 mm, respectively, with evaporation timescales exceeding 2 days, whereas deadwood stored ~0.7 mm of precipitation, and retained water for >7 days. Deadwood water retention increased with more advanced decomposition. Together the forest floor litter layer reduced soil water recharge, reduced soil evaporation rates, and insulated against ground heat fluxes thus impacting snowmelt patterns. Timeseries of deadwood water content revealed a diel cycle of stored water, water content increased during nighttime due to condensation of dew and fog and decreased during the day when vapor pressure deficit and evaporation were high. The water evaporating from the forest‐floor litter layer increased humidity, decreased temperature, and reduced vapor pressure deficit in the subcanopy atmosphere. Although, the absolute amounts of water storage in the forest-floor litter layer are relatively small, these storages were frequently filled and emptied with every precipitation event, thus effecting the overall soil water recharge. Overall, 18% of annual precipitation, or 1/3 of annual evapotranspiration, were retained in the forest-floor litter layer suggesting that overlooking litter interception may lead to substantial overestimates of recharge and transpiration in many forest ecosystems.

How to cite: Floriancic, M. G., Allen, S. T., Meier, R., Truniger, L., Kirchner, J. W., and Molnar, P.: Forest-floor litter and deadwood cycle significant amounts precipitation, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-13837, https://doi.org/10.5194/egusphere-egu23-13837, 2023.

EGU23-14167 | ECS | Orals | HS2.1.5

Dry seasons and dry years amplify the Amazon and Congo forests’ rainfall self-reliance 

Lan Wang-Erlandsson, Ruud van der Ent, Arie Staal, Patrick Keys, Delphine Clara Zemp, Ingo Fetzer, Makoto Taniguchi, and Line Gordon

Rainfall is a key determinant of tropical rainforest resilience in South America and Africa, of which a substantial amount originates from terrestrial and forest evaporation through moisture recycling. Both continents face deforestation that reduces evaporation and thus dampens the water cycle, and climate change that increases the risk of water-stress induced forest loss. Hence, it is important to understand the influence of forest moisture supply for forest rainfall during dry periods. Here, we analyze mean-years and dry-years dry-season anomalies of moisture recycling in the South American (Amazon) and African rainforests (Congo) over the years 1980-2013. Annual average reliance of forest rainfall on their own moisture supply (ρfor) is 26 % in the Amazon and 28% in the Congo forest.  In dry seasons, this ratio increases by 7% (or ~2 percentage points) in the Amazon and up to 30 % (or ~8 percentage points) in Congo. Dry years further amplify dry season ρfor in both regions by 4-5 %. In both Amazon and Congo, dry season amplification of ρfor are strongest in regions with a high mean annual ρfor. In the Amazon, forest rainfall self-reliance has declined over time, and in both Amazon and Congo, the fraction of forest evaporation that recycles as forest rainfall has declined over time. At country scale, dry season ρfor can differ drastically from mean annual ρfor (e.g., in Bolivia and Gabon, mean annual ρfor is ~30% while dry season ρfor is ~50 %). Dry period amplification of ρfor illuminates additional risks of deforestation as well as opportunities from forest conservation and restoration, and is essential to consider for understanding upwind forest change impacts on downwind rainfall at both regional and national scales.

How to cite: Wang-Erlandsson, L., van der Ent, R., Staal, A., Keys, P., Zemp, D. C., Fetzer, I., Taniguchi, M., and Gordon, L.: Dry seasons and dry years amplify the Amazon and Congo forests’ rainfall self-reliance, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-14167, https://doi.org/10.5194/egusphere-egu23-14167, 2023.

EGU23-14582 | Posters on site | HS2.1.5

Comparing tree ring chronology and soil water model for a hydric hemiboreal forest 

Andis Kalvans and Iluta Dauškane

Air temperature and hence potential evapotranspiration trends are clearly positive worldwide, while precipitation trends are unclear largely due to large inherent variability. Apparently, because of climate change increasing evapotranspiration is likely to lead to depletion of soil water reserves in many ecosystems, but ecosystem feedbacks can have a nonlinear impact of the water regime. For example, in a hemi boreal forest at a hydric setting, higher evapotranspiration due to higher temperatures can lead to improved soil aeration, facilitating the rejuvenation of woody vegetation and further increase of transpiration. Process-based soil water models can be used to investigate such phenomena. However, the models need to be validated. Long time series of the forest soil water regime are sparce. Instead, the tree-ring width data (chronology) can be used as a proxy for growing conditions in the past, as the soil water regime has the firs order controlling factor. We are constructing a Hydrus-1D soil-water model for three hydric forest sample plots in Latvia using the e-obs data set for model forcing. The model results then are compared to the local tree-ring chronology, particularly examining pointer years as extreme cases for evaluating hydrological situation. The model will provide opportunity for scenario investigation of the interactions between climate and soil water regime in hemiboreal forest ecosystem. This work was supported by ERDF postdoctoral research project “Groundwater and soil water regime under climate change” (No. 1.1.1.2/VIAA/3/19/524).

How to cite: Kalvans, A. and Dauškane, I.: Comparing tree ring chronology and soil water model for a hydric hemiboreal forest, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-14582, https://doi.org/10.5194/egusphere-egu23-14582, 2023.

EGU23-15252 | ECS | Orals | HS2.1.5

Former land use and tree age affects nitrate leaching from European forest soils 

Caitlin Lewis, Martin Lukac, Elena Vanguelova, and Matthew Ascott

Forest ecosystems are typically associated with good water quality; an ecosystem service often claimed as a benefit of afforestation schemes. However, legacy effects of historical land use, plus decades of elevated nitrogen deposition inputs from traffic pollution, and agricultural and industrial activities in combination with higher nitrogen scavenging by forests, have led to elevated nitrate leaching from forested lands across Europe. Elevated nitrate leaching threatens the quality of surface and groundwater. It is also related to soil acidification and depletion of base cations, compromising the nutritional status of the soil and, subsequently, current and future trees generations. Several variables that affect the response of nitrate leaching to elevated deposition inputs have previously been identified in long-term forest monitoring datasets. Here we collated a European-scale dataset from published literature of throughfall nitrate concentrations and nitrate leaching, and variables affecting this relationship, e.g. soil type, surrounding land use and climate, broadening the evidence beyond these long-term monitoring datasets.

We identified a variation in response to elevated deposition between coniferous and broadleaved forests. This could be partly attributed to the former land uses typically associated with the different tree species. Broadleaf forests planted on former arable land exhibited a different response to elevated deposition than afforested heathlands/grasslands and conifers planted on arable land. An age effect was also observed, with nitrate leaching from forest soils increasing with tree age until 80 years old for conifers and 50 years old for broadleaves, then declining as trees aged further. This research provides evidence to assess the timescale over which afforestation schemes can deliver expected benefits to water quality. It also highlights that considering former land use is important to identify locations in forested landscapes where groundwater nitrate concentrations may be elevated.  

How to cite: Lewis, C., Lukac, M., Vanguelova, E., and Ascott, M.: Former land use and tree age affects nitrate leaching from European forest soils, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-15252, https://doi.org/10.5194/egusphere-egu23-15252, 2023.

EGU23-17269 | ECS | Orals | HS2.1.5

How do bark beetle outbreaks impact water quality in temperate forested catchments? 

Daphné Freudiger, Bernd Ahrends, Henning Meedenburg, Birte Scheler, and Ulrike Talkner

Temperate forests provide ecosystem services such as protecting water environment, timber and fuel production, carbon sequestration, and reduction of nutrient loss. During the last decades, large forest areas were decimated world-wide by bark beetle attacks. Under climate change, drought and higher temperatures increase the risk of infestation. Future forest ecosystem services are therefore at risk of deterioration and it is essential to understand how bark beetle attacks and following management practices influence nutrient cycling, nitrate (NO3) and dissolved organic carbon (DOC) fluxes in seepage water. After dieback, accelerated mobilization of nutrients can be expected due to an increase in mineralization rates and the lack of plant nutrient uptake, whereas the lack of litter input may reduce nutrient leaching. The significantly reduced interception and evapotranspiration might furthermore increase soil water contents and seepage fluxes. Regeneration strategies (e.g. site clearance vs. keeping the dead trees, natural vs. artificial regeneration, regeneration with nurse crops) are decisive for the extent and persistence of the impact of calamities on water quality and quantity. We use a meta-data-analysis to gather knowledge out of approx. 60 studies around the world, to assess the expected behaviours of DOC and NO3 concentrations in seepage water and streams after bark beetle outbreaks in temperate forests and to identify gap of knowledge. Most studies focussed on nitrate leaching and only few on DOC. Overall, DOC concentrations increase in seepage water and streams directly after dieback, reaching a peak 2 to 3 years after disturbance. In the opposite, the first evidences of increased NO3 concentrations are visible approximately one year after disturbance and peak is reached within 3 to 10 years (on average after 5 years), when DOC decreases. NO3 maxima never exceeded drinking water limit. In all studies, DOC and NO3 concentrations recovered to pre-event or, in some cases, were even below the pre-dieback conditions only few years after the peak. Forest ecosystems seem therefore to be resilient to disturbances showing overall rapid recovery of ecosystem functions. However, the timing and duration of the concentration peaks largely differed among the studies, which might be explained by the extent and velocity of tree dieback in the studied areas, the harvest management practices and the type of vegetation re-growth after disturbance, but also by the local climatic conditions and the catchment size. Only few studies specifically analysed these effects on nutrient fluxes and their results differ considerably. More research is needed for assessing the influence of different regeneration strategies after calamities on water quality risks in forested catchments. A bark beetle attack currently decimating the Norway Spruce forest in the well-monitored Lange Bramke catchment (Harz, Germany), offers a unique opportunity to answer this question. With long-term datasets of NO3 and DOC concentrations in stream and the recent installation of a network of lysimeters at three soil depths in a) a healthy forest area, and infested areas b) with dead trees standing, and c) with site clearance, we will be able to better understand the effect of regeneration strategies on nutrient fluxes.    

How to cite: Freudiger, D., Ahrends, B., Meedenburg, H., Scheler, B., and Talkner, U.: How do bark beetle outbreaks impact water quality in temperate forested catchments?, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-17269, https://doi.org/10.5194/egusphere-egu23-17269, 2023.

EGU23-17565 | ECS | Posters on site | HS2.1.5

A Tendency Toward Further Advancement In Forest Digitalization Via Combined Sap Flow, Spectrometer, Soil, And Microclimate Data 

Riccardo Valentini, Jim Yates, Andrea Petroselli, Alexis Yaroslavtsev, Flavia Tauro, Francesco Renzi, and Shahla Asgharinia
The science of forest digitalization via technological innovation offers an opportunity to develop new methods for mass monitoring forest resources. A key constraint has been cost restraints preventing the mobilization and collection of big data to efficiently capture, store, and analyze retrieved data. The Internet of Things (IoT) and advances in microprocessing are steadily changing this. The TreeTalker® is a multisensory IoT-driven platform designed to detect and collect information on individual trees, where its nested sensor approach captures several key ecophysiological parameters autonomously and in quasi-real time at a relatively low cost.
Here we combine a new additional probe for the detection of soil parameters, mainly soil temperature and soil moisture. The aim of this study was to design a compatible soil probe with TreeTalker® platform with reasonable accuracy maintaining the principle of lower cost for mass monitoring. For this purpose, two surficial sensing frequency domain-based soil probes with 50 and 3000 kHz bands were designed and integrated into the TreeTalker® platform for real-time and continuous soil data collection. In order to demonstrate the capability of the new additional part, a three-phase experimental process was performed including (1) sensor sensitivity analysis, (2) sensor calibration using eight different soil types, (3) a survey on signal correlation with soil water content and soil matric potential and (4) long-term field data monitoring.
A negative linear correlation was demonstrated under temperature sensitivity analysis for both types of probes, and for calibration, nonlinear regression analysis was applied to collected samples, explaining the relationship between the sample volumetric water content (collected by digital scale) and the sensor frequency output. Based on a preliminary trial, we investigate that frequency signal has a stronger correlation with soil matric potential (R2= 80%) rather than soil water content (R2= 62%) due to the sensitivity of the probe under free and bound water. This opens a new window for water potential measurement which is a key parameter for the understanding of Plant-Soil interactions. Furthermore, in a field scenario, three TreeTalkers were mounted near the commercial precise soil sensors, so-called TDR systems (time domain reflectometry) to analyze the accuracy of the low-cost soil probe in comparison to TDR system for both wet and dry seasons in silty-loamy soil type. The results revealed a better correlation for collected data in the wet season than in the dry period. We also present an innovative electrical impedance analysis for detecting soil water potential and soil water content.  system for both wet and dry seasons in silty-loamy soil type. The results revealed a better correlation for collected data in the wet season than in the dry period.

How to cite: Valentini, R., Yates, J., Petroselli, A., Yaroslavtsev, A., Tauro, F., Renzi, F., and Asgharinia, S.: A Tendency Toward Further Advancement In Forest Digitalization Via Combined Sap Flow, Spectrometer, Soil, And Microclimate Data, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-17565, https://doi.org/10.5194/egusphere-egu23-17565, 2023.

EGU23-165 | ECS | Posters virtual | HS2.1.6

Hydrological model calibration in a Himalayan Catchment Using Remote sensing/Reanalysis Datasets. 

Mani Kanta Malla and Dhyan Singh Arya

Hydrological models are simplified mathematical representations of various hydrological processes and their interactions in a catchment. They are widely employed to simulate hydrological responses under diverse scenarios of climate, land use, land cover, and agricultural and soil management practices, which are helpful for planning water resources and management at the catchment scale. The parameters of the hydrological models are often optimised by calibrating them such that the observed and simulated streamflow match closely. Reliable prediction of hydrological variables of interest in ungauged or poorly gauged basins and addressing the uncertainty associated with the prediction is a challenging task as it is very difficult to calibrate the models due to the unavailability of measured hydrological responses. Escalating research interest in predicting hydrological fluxes at ungauged or poorly gauged catchments has been witnessed recently using distributed modelling, advanced scientific methods, and the availability of high-resolution satellite-based and reanalysis datasets used in model calibration. Additionally, the ability of remote sensing data sources to consider spatial variability is a further benefit in calibrating hydrological models, which lowers the level of uncertainty in the outputs. This proposed study focuses on calibrating 3 layered Variable Infiltration Capacity (VIC) model with soil moisture, and evapotranspiration obtained from different remote sensed and reanalysis data sets in the Upper Indus basin of the Hindukush Himalayan region. As the Upper Indus basin has limited meteorological stations and no gauging stations in the Indian mainland, the current study has much scope to quantify the water resources using different remote sensing/reanalysis datasets. The results expected from this study are to find the suitable variable and reanalysis product for the calibration of the VIC model and the uncertainty associated with various remote sensing and reanalysis products.

How to cite: Malla, M. K. and Arya, D. S.: Hydrological model calibration in a Himalayan Catchment Using Remote sensing/Reanalysis Datasets., EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-165, https://doi.org/10.5194/egusphere-egu23-165, 2023.

EGU23-523 | ECS | Posters on site | HS2.1.6

An assessment of the water availability for mountain communities in the Parvati basin, Western Himalaya using a distributed hydrological model 

Pradeep Srinivasalu, Anil Kulkarni, Srinivas Vv, and Satheesh Sk

The impact of changing climate on the Himalayas strongly influences the amount and timing of water available in the region. Millions of people in the downstream regions of Himalayan catchments depend on streams and rivers originating from the region for domestic consumption, livelihood, agriculture, and hydropower (Immerzeel et al., 2020). Many studies have highlighted the importance of snow and glacier melt towards water availability at the basin scale (Khanal et al., 2021; Prasad et al., 2019). However, the water availability at a much finer scale (i.e., to individual mountain communities) remains unquantified. Understanding the mountain communities' water availability is imperative to mitigate climate change impacts and ensure their water and food security (Kulkarni et al., 2021). In the present study, we aim to estimate the water availability to the communities in the Parvati Basin of Western Himalaya, including the contributions of snow and glacier melt, rainfall, and groundwater to runoff. The catchment has a total area of 1754 km2 and consists of 279 glaciers which cover an area of 395.6 km2. The volume of the glaciers and their mass balance are computed to understand the present state of the glaciers. The volume of the glaciers is estimated as 21.3 ± 3.8 km3 using laminar flow and scaling methods. The mass balance of the glaciers was estimated using the improved accumulation area ratio (IAAR) method as -0.44 ± 0.23 m w.e.a−1. We simulate the daily runoff in the catchment using the Spatial Processes in Hydrology (SPHY) model, which is a fully distributed cryospheric-hydrological model. The volume and mass balance results are used to define the model's initial conditions and constrain mass loss during the simulations. Further, the study also aims to understand the role played by seasonal snow cover on the water available to the mountain communities. The outcome of this assessment would help to facilitate making informed hydrological and agricultural policies to mitigate the impact of climate change.

How to cite: Srinivasalu, P., Kulkarni, A., Vv, S., and Sk, S.: An assessment of the water availability for mountain communities in the Parvati basin, Western Himalaya using a distributed hydrological model, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-523, https://doi.org/10.5194/egusphere-egu23-523, 2023.

EGU23-982 | ECS | Orals | HS2.1.6

Impact of mountain topography on potential evapotranspiration and water drainage 

David Luttenauer, Sylvain Weill, and Philippe Ackerer

Hydrological models are currently used to simulate the water cycle at the catchment scale using climatic forcing. For water management purposes, one of the most important components to be determined is drainage. The estimation of drainage into an aquifer is directly related to the water input (precipitation), the outputs through evaporation and transpiration, and water flow dynamics in the unsaturated zone. The output fluxes are difficult to estimate through direct measurements and are often estimated using mathematical models build on climatic processes and data. Amongst the climatic data that are used, solar radiation is a key parameter since it estimates the energy available for open surface or soil evaporation and plant transpiration. Solar radiation can be computed directly knowing the sun’s position, provided by satellite surveys (with a spatial resolution down to 6x6km2 and a time resolution of one hour) or interpolated from values measured at meteorological stations. Values based on observations should be preferred because direct computation is strongly biased due to the effects of weather conditions (cloud for example). In mountainous regions, the orientation of the hillslope regarding the sun's position can strongly impact the amount of solar energy arriving on the canopy or the soil.

The questions we address in this communication are the following: when applying physically based hydrological models to mountainous regions, is it really necessary to consider the potential sky obstruction due to the mountainous terrain of each grid cell to assess solar radiation? By rebound, does this strongly impact the estimation of evapotranspiration and water drainage to the aquifer?

To answer these questions, a mixed methodology that relies on two steps is proposed and tested. The first step consists of a theoretical computation of solar radiation for each grid cell of a given Digital Elevation Model using GIS tools. The second steps aim at correcting the first step computations to be consistent with measured or satellite data. For the first step, the (Scharmer, Greif 2000) model - which computes the 3 components of global radiation (direct, diffuse, and reflected by surrounding surfaces for clear sky conditions) – is used. The model also considers the local terrain to estimate the sky obstruction. In the second step, the data are averaged at the scale of the prescribed data (satellite or interpolated) and linearly corrected with a proportionality coefficient so that the average computed value fits the prescribed average value.

This methodology is then applied to a water catchment in the Vosges Mountains located close to Strasbourg (France). The proportionality coefficient varies locally between 0.2 and 2.5 showing that the local impact of topography on radiation is very significant. Using this correction coefficient in the Penman-Monteith formula, the relative difference in evapotranspiration is respectively -80% and +180% from the mean value for shaded areas and sunniest areas. For water drainage estimated through a conceptual model, the relative differences vary from -20% for the most exposed areas to +20% for the less exposed areas, demonstrating that orientation should be accounted for when simulating the response of mountainous watersheds.

How to cite: Luttenauer, D., Weill, S., and Ackerer, P.: Impact of mountain topography on potential evapotranspiration and water drainage, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-982, https://doi.org/10.5194/egusphere-egu23-982, 2023.

EGU23-1313 | Posters on site | HS2.1.6

Evapotranspiration of an Abandoned Grassland in the Italian Alps: Modeling the impact of shrub encroachment 

Davide Canone, Davide Gisolo, Ivan Bevilacqua, Alessio Gentile, Justus van Ramshorst, Maurizio Previati, and Stefano Ferraris

Shrub encroachment of grasslands in the Alps is still a poorly studied phenomenon. Therefore, this study analyses the possible effect of shrub encroachment on actual evapotranspiration (ETa) at an abandoned grassland in the Northwestern Italian Alps, colonised by Elaeagnus Rhamnoides shrubs. This is done by means of micrometeorological and eddy covariance data collected during four growing seasons. Additionally, the Hydrus 1D hydrological model modified to account for a soil column with two vegetation types is used.  This modified model is run with a variable percentage of shrubs on evapotranspiration, ranging from 0 to 80% and it is validated by using the measured eddy covariance-derived ETa. The Hydrus 1D model is also applied in its usual set-up, having only one vegetation type, to estimate the ETa from both grassland and shrubs separately.

The performance of the modified model with two vegetation types is acceptable, although it is very variable between different growing seasons and in dry condition it could be further improved (R between 0.50 in 2016 and 0.73 in 2014 considering the probable actual percentage of ETa affected by shrubs. The percentage varies between 20% in 2016 and 60% in 2014). Besides, the model captures the inter-annual variability of ETa. The agreement of cumulative simulated and observed ETa is good, since the deviation between observed and modelled cumulative ETa is always lower, in the four analysed growing seasons, than 50 mm.

The simulated ETa approximates the eddy covariance-derived ETa, however the modelled soil water content is very sensitive to precipitation events, more than the measured soil water content. Both models, with the modified and the usual setup, tend to overestimate the vegetation stress during dry periods. Nevertheless, the single vegetation model results allow us to conclude that the shrubs likely are responsible for an enhancement of ETa and an alteration of the hydrological cycle accordingly. Finally, we explore how some micro-meteorological drivers of ETa (vapour pressure deficit – VPD, net radiation, wind speed, air temperature and ground heat flux - G0) affect the difference between modelled and simulated ETa, and between simulated ETa from shrubs and from grass. Frequently, higher deviations from zero are found especially with high VPD and G0.

How to cite: Canone, D., Gisolo, D., Bevilacqua, I., Gentile, A., van Ramshorst, J., Previati, M., and Ferraris, S.: Evapotranspiration of an Abandoned Grassland in the Italian Alps: Modeling the impact of shrub encroachment, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-1313, https://doi.org/10.5194/egusphere-egu23-1313, 2023.

Mountain hydrology faces a number of specific challenges, such as the high spatial variability of conditions and processes in horizontal and vertical dimension, and the comparatively low density and limited representativity of hydrometeorological observation networks. Vít Klemeš (1990) characterized these challenges very pointedly when he noted that mountainous areas, despite their hydrological importance, represent “some of the blackest black boxes in the hydrological cycle”.

In the meantime, our knowledge about mountain hydrology has improved considerably, although the challenges can still be characterized as greater than for most lowland regions. Also, global hydrological models have become a research field in their own right since the time of Klemeš’ statement, and even though these models face similarly increased challenges in mountain regions, they can be useful for studying mountain regions and their water resources in a larger context. In addition, valuable information can be extracted from an overview of regional studies, as has been done, for example, in the mountain-specific parts of the IPCC Special Report on the Ocean and Cryosphere in a Changing Climate and the IPCC Sixth Assessment Report.

This contribution will discuss a comprehensive view from the mountains looking downstream, with a focus on the importance of mountain water resources for the lowlands.

Reference

Klemeš V, 1990. Foreword. In: Molnár L, ed. Hydrology of Mountainous Areas. Proceedings of a workshop held at Strbské Pleso (Czechoslovakia), June 1988. IAHS Publication 190, IAHS, Wallingford, ISBN 0-947571-42-6, p. 7

How to cite: Viviroli, D.: Mountain water resources and the importance of looking downstream, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-1408, https://doi.org/10.5194/egusphere-egu23-1408, 2023.

EGU23-1662 | ECS | Orals | HS2.1.6

Hydrological characteristics of Sutri Dhaka glacier catchment in the western Himalaya 

Sourav Laha, Parmanand Sharma, Sunil N. Oulkar, Lavkush Patel, Bhanu Pratap, and Meloth Thamban

The Himalaya is a massive cryospheric reserve, which provides a significant amount of fresh water to major Asian rivers like the Indus, Ganges, Brahmaputra, etc. Climate-induced cryospheric change is one of the major worldwide concerns, particularly in the Himalaya. Meltwater from glaciers and snow stabilises the downstream river runoff, and it buffers against drought during the driest years to some extent. The hydrological impact due to climate change in the high Himalayan catchments is potentially amplified by the shrinkage of snow and ice reserves. Therefore, it is important to analyse the potential hydrological changes at catchment to regional scales in the Himalaya. Hydrological changes at the regional scale are mainly determined by glacier catchment scale hydrology. Presently, understanding the regional scale discharge in the Himalaya suffers from large uncertainties, and one major source is the lack of glacier catchment scale hydrological understanding. Motivated by the above, here we are studying the glacio-hydrological characteristics of the Sutri Dhaka Glacier (debris-free glacier) catchment, which is located in the Chandra basin, western Himalaya. The glacierised area is ~20 km2, and the total catchment area is ~45 km2.

To the glacier catchment, we are applying an hourly timescale glacio-hydrological model to simulate discharge and the corresponding hydrograph components from 1980 to 2022. We also obtained extensive long-term field measurements of glacier mass balance, meteorological parameters, and discharge for the ablation season of 2016 to 2022 (with some gaps). These field data are used to calibrate the model parameters using a Bayesian framework and validate the simulated discharge and glacier mass balance. The simulated discharge variability from the diurnal to inter-annual time scale matches with the observations with reasonable accuracy (R2>0.75). Also, the model is able to capture the strong seasonality of the diurnal discharge amplitude, which has a direct relation to the storage-release properties of the glacier. Particularly, the diurnal discharge variability from the Himalayan glacier catchment is not well explored in the literature. We have also computed the associated uncertainties in the model as we as in the observations. Our present analysis will help to improve the existing process-based understanding of the glacier catchment scale discharge from the glacierised Himalayan region.

How to cite: Laha, S., Sharma, P., Oulkar, S. N., Patel, L., Pratap, B., and Thamban, M.: Hydrological characteristics of Sutri Dhaka glacier catchment in the western Himalaya, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-1662, https://doi.org/10.5194/egusphere-egu23-1662, 2023.

EGU23-1676 | ECS | Orals | HS2.1.6

Seasonal variation in stable isotope compositions of surface waters from Upper Sutlej River Basin: Estimation of the moisture source 

Kanishak Sharma, Anil Kumar Gupta, Sameer Kumar Tiwari, and Nikitasha Chatterjee

The stable isotopes of water, 18O and 2H, are impacted by climatic events that give them a distinct fingerprint of their source. Investigating the origin of river water requires this fingerprint as a precursor. On an annual basis and at the global level, the flow of moisture from the oceans and its return via rainout and runoff is similar to a dynamic equilibrium. Rivers in the Himalayan region have their moisture source in various end members which include glacier/snow melting, rainfall/runoff, and groundwater/springs. Sutlej River is one such river that travels across the Himalaya and receives its waters from all the aforementioned regions. 105 water samples from 36 different locations have been collected from the Upper Sutlej River Basin in the pre-monsoon, post-monsoon, and lean seasons to study the isotope system of surface water in the basin. A seasonal cycle with high δ18O and δD values (‰) during the pre-monsoon (March to May; −14.42, −114.94), intermediate values during the winter (lean season) (December to February; −12.63, −105.10), and low values during the post-monsoon (October to November; −12.13, −101.6) is observed. The river falls in the western Himalaya that receives precipitation both from the Indian Summer Monsoon (ISM) as well as from the Western Disturbances (WDs). The intercept and the d-excess values in the water samples fluctuate due to the variable contributions from these two moisture sources and the related rainfall in different seasons which are generally higher than the global meteoric waters. The 168-hour back trajectories in different seasons using HYSPLIT model converging at a height of 4,200 m a.s.l. (mean elevation of the Upper segment of the catchment) for moisture source identification have shown that winds mainly blow from south or south-east with moisture source from the Arabian Sea and the Bay of Bengal in summer and monsoon seasons, whereas in winter and spring seasons winds blow mainly from the west bringing moisture from the Central Asian and Eurasian water bodies through Western Disturbances. The results of HYSPLIT model and isotopic analysis indicate a dominant contribution of Western Disturbances and glacier melt in the upper segment of the basin which is consistent with recent data on glacier retreats in the Himalayan region.

Keywords: Himalayan Rivers, Sutlej River, Stable Isotopes, Western Disturbances, Indian Summer Monsoon.

How to cite: Sharma, K., Gupta, A. K., Tiwari, S. K., and Chatterjee, N.: Seasonal variation in stable isotope compositions of surface waters from Upper Sutlej River Basin: Estimation of the moisture source, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-1676, https://doi.org/10.5194/egusphere-egu23-1676, 2023.

EGU23-1746 * | ECS | Orals | HS2.1.6 | Highlight

Unravelling the origins of precipitation over the world’s water towers 

Jessica Keune and Manuela Brunner

Mountain regions supply around 22% of the world's population with freshwater — from precipitation over these water towers to melt water from snow packs and glaciers. However, the frozen reservoirs of water that usually act to buffer precipitation deficits are diminishing as a result of climate change. As a consequence, precipitation will become the main source of freshwater supplied by these water towers. Yet, already today, precipitation deficits over many water towers frequently cause severe droughts that further induce supply deficits in downstream regions. 

Here, we unravel the origins of precipitation over the most important water towers worldwide and illustrate their dependency on upwind land regions. Using a moisture tracking framework constrained by satellite observations, we disentangle the local and remote surface drivers of drought over these water towers and highlight the role of forested and irrigated regions during these events. Our results indicate that many water towers can self-sustain their precipitation during drought events through an increased self-supply of moisture for precipitation: over the water tower of the Ganges-Brahmaputra, for example, around 80% of the precipitation during drought events is supplied by the water tower itself and its dependent downstream region. Our findings highlight the vulnerability of the world's most important water towers to drought from an atmospheric perspective and outline the potential of localized forest and land management practices to secure freshwater to billions of people in the future.

How to cite: Keune, J. and Brunner, M.: Unravelling the origins of precipitation over the world’s water towers, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-1746, https://doi.org/10.5194/egusphere-egu23-1746, 2023.

Streamflow seasonality in mountain regions is besides climate often shaped by reservoir regulation. Such regulation is particularly important in the Alps where meltwater from glaciers and the snowpack are captured in reservoirs to generate hydropower during the winter season. While reservoirs affect streamflow seasonality, information on past seasonal reservoir operation patterns is rarely publicly available. Consequently, little is known about spatial variations in reservoir storage and release signals in dependence of climate and catchment characteristics. Here, we develop a generalized additive modelling approach to reconstruct daily and seasonal reservoir patterns from observed streamflow time series that encompass a period before and a period after a known year of reservoir construction.

We apply this approach to reconstruct the seasonality of reservoir regulation, i.e. information on when water is stored in and released from a reservoir, for a dataset of 74 regulated catchments in the Central Alps. Using these reconstructed seasonal regulation patterns, we identify groups of catchments with similar reservoir operation strategies using functional clustering. We find that reservoir management varies by catchment elevation. Seasonal redistribution from summer to winter is strongest in high-elevation catchments, where reservoirs are mostly used for hydropower production, while seasonal redistribution is much weaker in the downstream regions, where reservoirs are used for a range of different purposes. The clear relationship between reservoir operation and elevation has practical implications. First, these elevational differences in reservoir regulation can and should be considered in hydrological model calibration. Furthermore, the reconstructed reservoir operation signals can be used to study the joint impact of climate change and reservoir operation on different streamflow signatures, including extreme events. Last, the potential of regulation as a climate adaptation measure may vary for the high-elevation and downstream regions.

How to cite: Brunner, M. I. and Naveau, P.: Disentangling reservoir regulation patterns from natural streamflow in the Alps and their downstream regions, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-1948, https://doi.org/10.5194/egusphere-egu23-1948, 2023.

The Tibetan Plateau functions as the Asian water tower. It is highly sensitive to climate change and is warming faster than low-lying areas. The snow-melt dynamics are being perturbed, precipitation and evaporation patterns are shifting, and permafrost is degrading. Climate change therefore threatens the basin water supply as well as agriculture, hydropower, and industry which depend on it. The scientific questions we emphasized here are: (i) How evaporative water demand (EWD) changes in space and time during the current decades across the Asian water tower? (ii) Which driver should be attributable for the change? (iii) How EWD change informs the potential alteration of surface water resources in the Asian water tower? The expected outcomes would improve our understanding of the hydroclimatic change in the Asian water tower as well as other high-water yielding mountainous regions worldwide. 

How to cite: Xu, S.: Trends in evaporative water demands in the Tibetan Plateau and its implication for hydroclimatic change, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-2205, https://doi.org/10.5194/egusphere-egu23-2205, 2023.

In snow-dominated regions, snowmelt water plays a critical role in recharging the subsurface and generating streamflow. With a changing climate, the fraction of annual precipitation that falls as snow will probably decline. Rainfall and snowmelt water have different interactions with the subsurface and potentially vegetation, thus affecting the partitioning of precipitation into subsurface storage and streamflow. Currently, our understanding of how snow-to-rain transition affects this hydrologic partitioning in mountainous catchments is still limited. To take the best management practices for climate change adaptation, it is of critical importance to study how a catchment responds to such environmental disturbances.

In this study, we use the geophysics-informed hydrologic modeling to study the effect of snow-to-rain transition on hydrologic partitioning in a snow-dominated mountainous catchment in Idaho, USA. In the modeling, the subsurface structure was extracted from velocity map obtained from seismic refraction tests. Many studies has highlighted the importance of the heterogeneous subsurface in water partitioning in catchments, but accurate characterizations with traditional field techniques such as drilling are challenging. The hydrologic model developed from geophysical results is then calibrated with historical hydrometeorological measurements. Two climate change scenarios are designed to study the impact of warming on streamflow generation and water storage. In Scenario 1, a uniform warming is considered throughout the year, and an air temperature increase (+2.5 °C) is applied to change the phase of precipitation. In scenario 2, warming is only applied to the snow season (i.e., from December to April). The numerical modeling results show that a uniform warming (scenario 1) significantly promotes evapotranspiration (ET), and streamflow becomes less productive. Warming in the snow season only (scenario 2) induces an earlier, flashier streamflow but the partitioning of precipitation between storage and streamflow is not significantly changed. Compared to simulation results from traditional hydrologic modeling (without the heterogeneous deep subsurface), geophysics-informed hydrologic modeling reveals the importance of water storage in the fractured bedrock in response to the climate change.

How to cite: Chen, H. and Niu, Q.: Effect of snow-to-rain transition on precipitation partitioning in a mountainous catchment: insights from geophysics-informed hydrologic modeling, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-2920, https://doi.org/10.5194/egusphere-egu23-2920, 2023.

EGU23-7013 | Orals | HS2.1.6

Could land management modify water resources in Mediterranean mountain areas? 

Javier Zabalza-Martínez, Estela Nadal-Romero, Manel Llena, Melani Cortijos-López, Teodoro Lasanta-Martínez, Juan Ignacio López-Moreno, Sergio M. Vicente-Serrano, Diana Pascual, and Eduard Pla

Water resources availability is one of the main concerns for policy makers around the World. In the Mediterranean basin, this problem has been increased given the extreme variability in climate and the land use changes that have occurred during the last century (i.e. land abandonment). Streamflow and other environmental variables related to vegetation have been analysed in three Mediterranean mid-mountain basins under conditions of Climate Change (CC), under conditions of Land Use Change (LUC) and under its Combined Action (CA). The Land Use changes have been defined in the framework of the Life MIDMACC project and are related to land management through shrubland cleaning activities in abandoned fields and forest management that is determined by a 50% decrease in tree density in a forest community.

Three basins (Leza, Estarrún and L'Anyet) have been simulated using the Regional Hydro-Ecologic Simulation System (RHESSys) for the periods 2035-2064 and 2070-2099. The aim of the study is to determine the impacts of climate change and land management on both streamflow and other variables such as Net Primary Production or Potential Evapotranspiration in these basins (representative of Mediterranean mid-mountains) in order to analyse how the management proposed can be used to adapt these basins to climate and whether it is capable of mitigating the forecast reduction in streamflow associated with climate trends.

The results with LUC reveal a clear positive trend, increasing the streamflow in the basins of Leza and L'Anyet rivers (+9.76% and +4.70%) and slightly decrease (-0.13%) in Estarrún river due to the limited area to be managed. The combined action (CA) shows, in general, an attenuation in the clear negative trend of streamflow under climate change (CC) conditions. This suggests that the land management proposed in the LIFE MIDMACC project could help the adaptation of Mediterranean mid-mountain basins to climate change and the mitigation of its effects.

Acknowledgements: This research project was supported by the Life MIDMACC project ((LIFE18 CCA/ES/001099)) project funded by the European Commission. Melani Cortijos-López is working with an FPI contract (PRE2020-094509) from the Spanish Ministry of Economy and Competitiveness associated to the MANMOUNT project. Manel Llena has a “Juan de la Cierva Formación” postdoctoral contract (FJC2020-043890-I/AEI/ 10.13039/501100011033) from the Spanish Ministry of Science and Innovation.

 

 

How to cite: Zabalza-Martínez, J., Nadal-Romero, E., Llena, M., Cortijos-López, M., Lasanta-Martínez, T., López-Moreno, J. I., Vicente-Serrano, S. M., Pascual, D., and Pla, E.: Could land management modify water resources in Mediterranean mountain areas?, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-7013, https://doi.org/10.5194/egusphere-egu23-7013, 2023.

EGU23-7433 | Posters on site | HS2.1.6

Future evolution of the snowpack in the Iberian peninsula 

Jesús Revuelto, César Deschamps-Berger, Juan Ignacio López Moreno, Laura Sourp, Sylvia Terzago, Francisco Rojas Heredia, and Marion Réveillet

The mountains of the Iberian peninsula host seasonal snowpacks in various environments, from mediterranean climate in the Sierra Nevada to alpine climate in the Pyrenees. This range of conditions is expected to result in different, but largely unknown, sensitivity of the snowpacks to the ongoing and future climate change. We modeled the snowpack in five sites which were selected over the peninsula for their environmental importance as indicated by their national park status. We downscaled the EURO-CORDEX meteorological forcings on a 250 m grid and forced SnowModel to obtain an ensemble of spatialized snowpack simulations over the historical period (1970-2005) and a projection period (2005-2100) considering different RCP scenarios. The accuracy of the simulation was evaluated with satellite snow cover images and in-situ measurements. The general decrease in snowpack impacts the hydrological cycle temporality and the frequency of snow droughts in the basins but is modulated by the varying climatic conditions between the study sites.

How to cite: Revuelto, J., Deschamps-Berger, C., López Moreno, J. I., Sourp, L., Terzago, S., Rojas Heredia, F., and Réveillet, M.: Future evolution of the snowpack in the Iberian peninsula, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-7433, https://doi.org/10.5194/egusphere-egu23-7433, 2023.

EGU23-7654 | Orals | HS2.1.6

The impact of climate change on fish habitat availability in mountain rivers 

Gianluca Filippa, Erica Vassoney, Alberto Viglione, Paolo Vezza, Giovanni Negro, Andrea Mammoliti Mochet, and Claudio Comoglio

Mountain rivers are threatened by various natural and human-induced impacts, all of them potentially altering the availability of habitats for fish communities. These impacts include, among others, climate- change-associated reduction of discharge and water abstraction by humans, e.g., for hydropower production and irrigation. A quantitative assessment of future water, and subsequent fish habitat, availability is therefore pivotal to the effective and sustainable management of water resources in mountain basins.

In this work, we investigated the effect of climate change on discharge and fish habitat availability in two alpine catchments in the Western Italian Alps.

Historical discharge was modeled by means of a relatively simple rainfall-runoff model (TUWmodel), whereas discharge projections were computed under different state-of-the-art greenhouse gas scenarios both for the near future (2041-2060) and the far future (2080-2099). Discharge was then translated into habitat availability with the MesoHABSIM (Mesohabitat Simulation Model) methodology, an approach that allows to simulate the variations in habitat availability for the local fish population (brown and marble trout).

We found significant changes in future runoff, in turn leading to marked changes in fish habitat availability, with contrasting response in glaciated vs non glaciated basins.

We demonstrated that the combination of a hydrological model, climate scenarios and habitat modeling allows the depiction of future ecological scenarios for alpine rivers, thereby representing a potential support for water resources management and decision-making.

 

How to cite: Filippa, G., Vassoney, E., Viglione, A., Vezza, P., Negro, G., Mammoliti Mochet, A., and Comoglio, C.: The impact of climate change on fish habitat availability in mountain rivers, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-7654, https://doi.org/10.5194/egusphere-egu23-7654, 2023.

High mountains, which exhibit alpine and subalpine characteristics, represent 15% of the earth’s land area and are estimated to contribute about 17% of global runoff. Depending on hydrogeological setting, a significant amount of catchment water can be stored in high mountainous underground as groundwater, which can contribute substantially to streamflow and represent an important water source. However, high-alpine catchments are often characterized by great geological complexity and highly heterogeneous hydraulic properties. For that reason, proper system characterization, monitoring and modeling remain challenging. In this study, we investigated a geologically complex alpine catchment in the Dolomites (Italian Alps) by combining hydrogeological investigation, hydrological monitoring and numerical modelling. A process based but spatially lumped hydrological model was applied to simulate the continuous measured catchment discharge in a period of three years, which covers a large variation of hydrodynamic conditions. The current model structure couples the sequential hydrogeological units within the studied catchment: (1) the fractured dolomitic rocks as bedrock aquifer and 2) the unconsolidated deposits accumulating on the slopes and at the valley floor as porous aquifer. In order to evaluate the model structure and parameterization in depth, we applied a multi-step evaluation approach considering both parameter sensitivity and uncertainty. The current modelling results demonstrate that the newly developed model can reproduce most discharge behavior of aquifers. The model indicates a dynamic linkage between surface and subsurface storage units during different flow conditions. Besides the matrix and conduit flow in fractured dolomitic aquifer, it highlights the important role of unconsolidated sediments (porous aquifer) to the storage and discharge behavior of the entire groundwater system. Furthermore, with the comprehensive model evaluation we learned the model structure deficit during extreme high flow condition and proposed a more detailed hydrogeological conceptual model to improve the model realism.

How to cite: Chen, Z., Lucianetti, G., and Hartmann, A.: Understanding collective behavior of bedrock and porous aquifers and their contribution to the total water storage and discharge dynamics of a high mountainous catchment – Dolomites, Alps, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-8899, https://doi.org/10.5194/egusphere-egu23-8899, 2023.

EGU23-10024 | Posters on site | HS2.1.6 | Highlight

Groundwater pathways and storage dynamics in steep mountain topography 

Kapiolani Teagai, John Armitage, Léo Agélas, Christoff Andermann, Niels Hovius, and Basanta Raj Adhikari

The Himalayan Mountain range is considered as a sustainable large water reservoir, often termed as “water towers of Asia”. This important reservoir of water is replenished annually by monsoon precipitation and is slowly drained in dry season. However, the processes that govern this water budget: the connectivity between perched aquifers situated high in the topography and the underlying fractured bedrock, is not well understood. In this study we investigate the surface-subsurface coupling and characterize the water pathways on a watershed scale. This will help to better understand where and how water is stored within the steep Himalayan topography. The study focuses on the unglaciated Kahule Khola watershed (~33 km²) situated north of Kathmandu in the central Himalayas (ranging from ~1000 to ~3500 m asl). During two field campaigns, we mapped the location of springs before (in May 2022) and after (in November 2022) the monsoon season. We characterized the surface infiltration capacity, soil permeability and carried out multiple ERT surveys covering the first 3000 m elevation profile. All these measurements were made on the major landforms (ridges, V-shaped gullies, and debris filled gullies) and different land use types (terraces, forest, meadow, and landslide debris), giving a clear picture of the landscape structure within this catchment. Infiltration rates and soil permeability are high with an average over 1 m/d, which suggests that infiltration dominates over surface runoff during the monsoon. ERT surveys show low resistivity (from ~100 to ~1000 Ω.m) at shallow depth in line with a weathered upper soil layer. Below this layer the ridges have a higher resistivity (from ~1000 to ~50000 Ω.m) while the gullies have very low resistivities suggesting saturated perched aquifers systems close to the surface. We found that spring heads move up or down slope to the seasonal water table fluctuations, tracing the topographic intersection of the groundwater with the surface. These observations suggest that water storage is substantial but not uniformly distributed within the landscape over time and space. We propose that besides the fractured bedrock, filled gullies and landslide deposits form perched water pockets with an important role in storing and distributing water, especially in the higher parts of mountain landscape.

How to cite: Teagai, K., Armitage, J., Agélas, L., Andermann, C., Hovius, N., and Adhikari, B. R.: Groundwater pathways and storage dynamics in steep mountain topography, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-10024, https://doi.org/10.5194/egusphere-egu23-10024, 2023.

EGU23-10266 | ECS | Orals | HS2.1.6

Are rock glaciers preferential meltwater pathways to alpine aquifers? 

Bastien Charonnat, Michel Baraer, Jeffrey M. McKenzie, Eole Valence, and Janie Masse-Dufresne

A limitation in generating reliable projections of the impact of climate change on subarctic glacierized watersheds is a lack of understanding of the involved processes. While glaciers are often the targets of glacierized watershed research, glaciers are only one of the many features controlling headwater hydrology. Recent studies suggest that the contribution and evolution of other hydrological components under climate change conditions, as well as their interactions with groundwater and surface runoff, must be considered to fully predict future climate change impacts. For example, rock glaciers are recognized for their hydrogeological significance, but their hydrologic processes remain understudied. We present a research program focused on a 5 km2 glacier and rock glacier continuum in the upper section of Shar Ta Gà’ (Grizzly Creek) in the Kluane First Nation territory, Yukon, Canada. The continuum is characterized by the absence of an apparent surface hydrology outlet and no substantial groundwater exfiltration has been detected in the Shar Ta Gà’ River situated directly downstream of the rock glacier. Some diffuse groundwater seepages have been mapped but their yield represent a fraction only of the volumes that are expected from the glacier drainage area.

We apply a multimethod approach (including geophysics, hydrochemistry, and UAV based surveying) to characterize the hydrological and hydrogeological behavior of the Shar Ta Gà’ rock glacier in a context where drilling is prohibited. Here we present results from a distributed hydrologic monitoring network of extreme precipitation events that occurred between 2018 and 2022. The network records water pressure, electrical conductivity, water temperature, hydrometeorological data and time lapse images. The results depict the rock glacier as a complex, multi-channel, evolutive hydrogeological system that collects water from upstream channels and from a porous surface. The water is distributed among different reservoirs and/or preferential channels. The rock glacier appears being a node in the hydrological and hydrogeological system, collecting the waters from the continuum and allowing their transfer to granular aquifers and possibly fractured aquifers.

How to cite: Charonnat, B., Baraer, M., McKenzie, J. M., Valence, E., and Masse-Dufresne, J.: Are rock glaciers preferential meltwater pathways to alpine aquifers?, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-10266, https://doi.org/10.5194/egusphere-egu23-10266, 2023.

The Andes are among the regions most affected worldwide by water insecurity with an increasing number of vulnerable people. Particularly seasonally dry regions such as the Bolivian-Peruvian Altiplano and the Dry Andes of Central Chile and Western Argentina exhibit considerable water stress due to increasingly adverse impacts from climate and land use changes, and growing water demand.

Adaptation to changing water availability is therefore a priority, but systematic scientific and diverse knowledge on adaptation policies and experiences has barely been documented for the Andean region. Here we present the first comprehensive assessment of climate change adaptation in the entire Andes for different adaptation types (management and planning, monitoring system, nature-based solutions, grey infrastructure, financing, and awareness and behaviour) and policies (climate change law, glacier law, Nationally Determined Contributions). This study is based on work contributed to and recently published in the IPCC’s Sixth Assessment Report, Working Group II (Chapter 12: Central and South America).

In the last two decades, several policies on climate change, water protection, regulation and management laws for adaptation in the mountain water sector have been implemented. The first Framework Law on Climate Change was implemented in Peru (2018) and is under way in Colombia, Chile and Venezuela. One milestone represents the Glacier Protection Law in place in Argentina (2010–2019) and under construction in Chile (since 2005). Furthermore, new water laws that include principles of integrated water resource management have entered into force, for example, in Peru (2009) and Ecuador (2014), or are under way in Colombia (since 2009). However, current realities in the Andes show major challenges in implementing integrated and sustainable water management mechanisms and policies. These are related but not limited to political and institutional instabilities, governance structures, fragmented service provision, lack of economies of scale and scope, corruption and social conflicts.

Although a growing body of climate change adaptation-related policies and initiatives exist for the Andes, evidence on their effectiveness is scarce. In many parts of the region the level of success of adaptation measures depends largely on the governance of projects and stakeholder-based processes and is closely related to their effectiveness, efficiency, social equity and sociopolitical legitimacy. Examples of successful implementation linked to e.g. watershed protection include water funds (e.g. Quito, Ecuador) and stakeholder platform processes (e.g. Moyobamba, Peru). Even less evidence has been reported for limits of adaptation or maladaptation experiences in the water sector. Most barriers to advance adaptation in the Andes are associated with missing links of science–society–policy processes, institutional fragilities, pronounced hierarchies, unequal power relations and top-down water governance regimes.

Adaptation gaps could be bridged by strengthening transdisciplinary research at the science-policy interface with blended bottom-up and top-down approaches in locally tailored adaptation agendas. Recently, the inclusion of indigenous and local knowledges in current adaptation baselines has attracted increasing attention, particularly in regions with a high share of indigenous peoples, such as Ecuador, Peru and Bolivia. Important questions centre around how to integrate diverse knowledge from the early planning stages on, to achieve enhanced or transformational adaptation building on co-produced knowledge.

How to cite: Huggel, C. and Drenkhan, F.: Assessment of climate change adaptation to improve water security in the Andes: current policies, remaining gaps and future opportunities, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-11312, https://doi.org/10.5194/egusphere-egu23-11312, 2023.

EGU23-11342 | Posters on site | HS2.1.6

Locally relevant and accurate climate impact assessments: A case study for Bhutan 

Mark Hegnauer, Laurene Bouaziz, Bart Van den Hurk, Philippe Floch, Hideki Kanamaru, and Alessandra Gage

Understanding the impact of climate change on water resources is crucial for selecting adequate adaptation strategies at a local scale. Global meteorological re-analysis datasets are useful to evaluate current-day climate conditions and trends, as a first step in a climate change assessment in poorly gauged basins. However, these datasets often lack the level of detail to calculate meaningful climate impacts at a local scale, especially in mountainous regions, where topography and orographic effects play a crucial role on the temporal and spatial variability of climate characteristics and change. In this study, we test how the combined use of global, regional and local datasets together with fieldwork result in locally relevant climate change impact assessment. The method is applied in Bhutan, a country with large differences between hydroclimatic zones, caused by the steep topography and the occurrence of the annual Monsoon rains in the Southern half of the country. The results of this study show the large variability between different global datasets in terms of precipitation volumes. The comparison of global, regional and local meteorological datasets in combination with locally observed streamflow data suggest that the regional re-analysis dataset is the most reliable and plausible to use for the climate impact assessment. Interestingly, the two global datasets used in this study, ERA5 (Hersbach et al., 2018) and W5E5 (Lange et al., 2021), seem to either underestimate (W5E5) or overestimate (ERA5) the precipitation considerably. The regional Indian Monsoon Data Assimilation and Analysis (IMDAA, Ashrit, 2020) precipitation re-analysis dataset seems to best represent the current climate conditions in Bhutan. This conclusion was further supported during a field visit, which highlighted that the spatial variability of the precipitation was likely not well captured the local precipitation gauges, which were mostly in the valleys. As this local data is used for the bias correction of the W5E5 dataset, it is likely that W5E5 is also not representative of the spatial variability of the local climate in Bhutan. This study demonstrates the importance of local knowledge, locally observed hydrological data and fieldwork to strengthen the local and regional climate impact assessments.

References

Ashrit, R., Indira Rani, S., Kumar, S., Karunasagar, S., Arulalan, T., Francis, T., et al. (2020). IMDAA regional reanalysis: Performance evaluation during Indian summer monsoon season. Journal of Geophysical Research: Atmospheres, 125, e2019JD030973. https://doi.org/10.1029/2019JD030973  

Hersbach, H., Bell, B., Berrisford, P., Biavati, G., Horányi, A., Muñoz Sabater, J., Nicolas, J., Peubey, C., Radu, R., Rozum, I., Schepers, D., Simmons, A., Soci, C., Dee, D., Thépaut, J-N. (2018): ERA5 hourly data on pressure levels from 1959 to present. Copernicus Climate Change Service (C3S) Climate Data Store (CDS). (Accessed on < DD-MMM-YYYY >), https://doi.org/10.24381/cds.bd0915c6

Lange, S., Menz, C., Gleixner, S., Cucchi, M., Weedon, G.P., Amici, A., Bellouin, N., Schmied, H.M., Hersbach, H., Buontempo, C., Cagnazzo C., 2021. WFDE5 over land merged with ERA5 over the ocean (W5E5 v2.0). ISIMIP Repository. https://doi.org/10.48364/ISIMIP.342217

How to cite: Hegnauer, M., Bouaziz, L., Van den Hurk, B., Floch, P., Kanamaru, H., and Gage, A.: Locally relevant and accurate climate impact assessments: A case study for Bhutan, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-11342, https://doi.org/10.5194/egusphere-egu23-11342, 2023.

EGU23-12879 | ECS | Posters on site | HS2.1.6

Trend analyses and characterization of discharge patterns of Austrian springs 

Magdalena Seelig, Simon Seelig, Jutta Eybl, and Gerfried Winkler

Climate change alters the processes and components of the global water cycle. With about 50 % of the Austrian water supply depending on springs, the response of spring discharge to changes in climate is a key question of sustainable water resources management. The monitoring system of the Hydrographic Service of Austria provides long-term data of 94 springs distributed over whole Austria. With this study we provide trend analyses related to climate change and statistical analyses of spring discharge patterns related to their runoff characteristics on a national scale. The analyses account for the structure of the time series and address requirements of objectivity, transparency and reproducibility. Trend significance is assessed employing the seasonal Mann-Kendall test, and trend magnitude is calculated by the Theil-Sen slope. Autocorrelation function and pardè coefficient are calculated for each spring, similarities are explored using cluster analysis and set in a regional context. The results identify spatiotemporal patterns across Austria and highlight the significance of accurate spring flow characterization with regard to future challenges of water resources management.

How to cite: Seelig, M., Seelig, S., Eybl, J., and Winkler, G.: Trend analyses and characterization of discharge patterns of Austrian springs, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-12879, https://doi.org/10.5194/egusphere-egu23-12879, 2023.

EGU23-13133 | ECS | Posters on site | HS2.1.6

Dynamics of multi-specie pasturelands under potential climate changes. The Gran Paradiso Park of Italy. 

Sonia Morgese, Francesca Casale, and Daniele Bocchiola

Climate change’s effects are remarkable on water systems, especially for alpine mountain regions. This study aims to assess the impact of climate change upon productivity of mountain pastures in the Gran Paradiso National Park (GPNP), Italy. For this purpose, some agro-climatic indices were introduced. GPNP dynamics are linked to the complex cryospheric hydrology of Alpine catchment and to the interspecies competition, which are in turn expected to change remarkably under prospective global warming scenarios. The hydrological Poli-Hydro model was used to simulate the cryospheric processes affecting the hydrology of high altitude catchments of the area. The Poli-Pasture model was developed for the simulation of pasture vegetation growth, and completed with adaptation of the CoSMo model, to consider interspecific competition. Two species were chosen for low altitude (elevation lower than 1800 m a.s.l.), e.g. Trifolium Alpinum and Dactylis Glomerata, and two species, Festuca Rubra and Nardus Stricta, for high altitude (elevation greater than 1800 m a.s.l.).

Model calibration and validation were performed against LAI (Leaf Index Area) during 2005-2019, using observed values available from satellite imagery.

Through four scenarios from the Sixth Assessment Report of IPCC (SSP1-2.6, SSP2-4.5, SSP3-7.0 and SSP5-8.5) applied to six GCM models (CESM2, CMCC, EC-EARTH3, HADGEM3 and MPI-ESM), meteorological data up to the year 2100 were derived. Using such climate projections, future agro-climatic indices, leaf area index and pasture yield were estimated.

According to IPCC projections, during growing season, temperature will noticeably increase at the end of the century, especially in high altitude areas, where mountain areas will experience highest temperature eve, with few heat wave days.

Due to increasing temperatures, a potential increase in productivity has been found in higher areas (up to 96% more by 2050 and 123% in by 2100, according to SSP5 8.5 scenario) and a lower change in lower elevation areas. The results provide preliminary evidence of potential livestock, and thereby economic development in the valley at higher altitudes than now. Under reduction of precipitation in summer, decrease in water consumption is expected, with possible lack of available water.

How to cite: Morgese, S., Casale, F., and Bocchiola, D.: Dynamics of multi-specie pasturelands under potential climate changes. The Gran Paradiso Park of Italy., EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-13133, https://doi.org/10.5194/egusphere-egu23-13133, 2023.

Recurrent flood estimation studies in Himalayan catchments located in India are crucial and require abundant monitoring and supervision. Reliable estimation of design floods for mountainous catchments corresponding to various return periods is challenging. Recently, climate change has exacerbated this challenge which pose a serious threat to the water resources within Himalayan region. The Geomorphology based Unit hydrograph theory can provide reliable estimates of design floods for Himalayan catchments. The theory involves determination of Geomorphological Instantaneous Unit Hydrograph (GIUH) corresponding to a catchment and utilizing the GIUH to predict design flood for a design rainfall input. In this study, it is envisaged to model the complex dynamics of floods in a Himalayan catchment by using a modified version of GIUH which is known as Equivalent Geomorphological Instantaneous Unit Hydrograph (E-GIUH). EGIUH overcomes many limitations associated with the conventional GIUH. The application of E-GIUH is performed for Seer catchment which is a sub-basin of Sutlej River basin. The design rainfall input to the E-GIUH is determined from Indian Meteorological Department (IMD) gridded rainfall data for the present (1951-2019) as well as the future time periods (2021-2060 and 2061-2100). Coupled Model Intercomparison Project phase 6 (CMIP6) experiments are considered to determine future projections of rainfall over Seer catchment which are subsequently used to estimate design rainfall input for future time periods. Design flood estimates are obtained for various Shared Socioeconomic Pathways (SSPs), particularly SSP126, SSP245 and SSP585 scenarios from CMIP6 experiments. The geomorphological descriptors used for development of E-GIUH model of the Seer catchment are evaluated using the GIS framework.

Keywords: Climate Change, CMIP6, E-GIUH, IMD, SSP, Seer Catchment

How to cite: Rana, S. and Chavan, S. R.: Design Flood estimation based on Equivalent Geomorphological Instantaneous Unit Hydrograph for a Himalayan catchment, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-13139, https://doi.org/10.5194/egusphere-egu23-13139, 2023.

EGU23-13389 | Orals | HS2.1.6

Tropical Alpine Ecosystems under climate change: Paramos and moorlands in peril 

Fernando Jaramillo, Kristian Rubiano, Nicola Clerici, and Adriana Sánchez

Tropical Alpine Ecosystems are high-altitude grasslands located above 3000 m.a.s.l. along the tropical belt of three continents. Their unique vegetation and soil characteristics, in combination with low temperature and abundant precipitation, create the most advantageous conditions for regulating and storing surface and groundwater. However, increasing temperatures and changing patterns of precipitation due to greenhouse-gas-emission climate change are threatening these fragile environments, reducing their extent and modifying their altitudinal distribution range. Here, we investigate the impact of climate change on the distribution and extent of global Tropical Alpine Ecosystems. We use an ensemble of historical and projected climate data (SSP585) from seven General Circulation Models from the Coupled Model Intercomparison Project Phase 6 (CMIP6) to estimate annual average values of temperature and annual accumulated values of precipitation for reference (1985-2014) and far future (2070-2100) 30-year periodos. We produced the 95% probability current and future hydroclimatic spaces for every ecosystem to determine the range at which Tropical Alpine Ecosystem currently thrives in the climatic space, and investigate a number of hydroclimatic variables. Then, we used the projected climate time-series data to assess the current Tropical Alpine Ecosystem areas that will be unable to keep up with the temperature and precipitation changes by exceeding their reference climatic boundaries in the far future. Overall, our results showed that the Tropical Alpine ecosystem would drastically reduce its extent. Approximately 45% of its current extent will experience hydroclimatic conditions beyond their reference climatic boundaries. For example, the Ethiopian montane moorlands in Africa will be the most impacted ecoregion with a reduction of approximately 95% of its current extent. For the case of páramos in the North of the South American continent, increasing temperatures and changing precipitation will render ~50% of the current extent unsuitable for these ecosystems during the dry season. Our results highlight the magnitude of the impacts of climate change on Tropical Alpine Ecosystem and the vulnerability of water security of millions of people who depend on its ecological functioning. These results also have implications for biodiversity conservation, as endemic species will be threatened by habitat reduction and shifts in their distribution ranges.

How to cite: Jaramillo, F., Rubiano, K., Clerici, N., and Sánchez, A.: Tropical Alpine Ecosystems under climate change: Paramos and moorlands in peril, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-13389, https://doi.org/10.5194/egusphere-egu23-13389, 2023.

EGU23-13993 | Posters on site | HS2.1.6

Statistical-topographical mapping of rainfall over mountainous terrain with the β-IDW approach 

Jan Wienhöfer, Lucas Alcamo, Jan Bondy, and Erwin Zehe

We present a robust approach for quantitative precipitation estimation (QPE) for water resources management in mountainous catchments, where rainfall sums and variability are correlated with orographic elevation, but density of rain gauges does not allow for advanced geostatistical interpolation of rainfall fields. 
Key of the method is modelling rainfall at unobserved locations by their elevation-dependent expected daily mean, and a daily fluctuation which is determined by spatial interpolation of the residuals of neighbouring rain gauges, which are scaled according to the elevation difference. The scaling factor is defined as the ratio of covariance and variance, in analogy to the "beta" used in economics.
The approach is illustrated for the Chirilu catchments (Chillón, Rímac, Lurín) in the Andes near Lima, Peru. The results are compared to conventional IDW interpolation and a merged national rainfall product. The method results in QPE that are better matching with observed discharges. The β-IDW approach thus provides a robust and flexible means to estimate rainfall input to mesoscale mountainous catchments.

 

How to cite: Wienhöfer, J., Alcamo, L., Bondy, J., and Zehe, E.: Statistical-topographical mapping of rainfall over mountainous terrain with the β-IDW approach, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-13993, https://doi.org/10.5194/egusphere-egu23-13993, 2023.

EGU23-15315 | Orals | HS2.1.6 | Highlight

Socio-hydrological pathways: Cryosphere changes and adaptation strategies in the Trans-Himalaya of Ladakh, India 

Marcus Nüsser, Dagmar Brombierstäudel, Mohd Soheb, and Susanne Schmidt

The Himalayan cryosphere is shrinking at an accelerating rate. This alarming trend is accompanied by more frequent natural hazards that threaten exposed mountain communities. Problems range from damages of irrigation canals and eroded fields to massive destruction of human habitat. Predicted changes in meltwater supply, modelled under the generic term ‘peak water’, require greater and concerted effort to understand and support local adaptation strategies to cope with experienced and predicted water scarcity. Regional development processes are further characterised by rapid and largely unplanned urbanisation, infrastructure development and related environmental degradation exacerbating risks for large numbers of people already affected by climate change. To meet these grand challenges, an interdisciplinary research perspective is needed for the Himalayan region based on the integration of natural and social sciences. Therefore, an improved understanding of socio-hydrological pathways is necessary to capture local and regional particularities and dynamics, including cryosphere changes, glacio-fluvial runoff, socioeconomic processes, indigenous environmental knowledge, and external development interventions. Based on a long-term study conducted in the Trans-Himalayan region of Ladakh, we explore the role of land use changes, water harvesting infrastructures, including implementation of ice reservoirs (so-called “artificial glaciers”) and construction of improved irrigation networks. Furthermore, the role of social institutions ranging from village to non-governmental organizations and state-sponsored development programs are considered. The presentation uses the case study of Ladakh to develop a grounded socio-hydrological framework for the fragile Trans-Himalayan region that may be used as a basis for sustainable development pathways.

How to cite: Nüsser, M., Brombierstäudel, D., Soheb, M., and Schmidt, S.: Socio-hydrological pathways: Cryosphere changes and adaptation strategies in the Trans-Himalaya of Ladakh, India, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-15315, https://doi.org/10.5194/egusphere-egu23-15315, 2023.

EGU23-15317 | ECS | Posters on site | HS2.1.6

Assessing the impact of climate change on Hydrological regime of Afghan catchments 

Jamal Shokory, Pascal Horton, Bettina Schaefli, and Stuart Lane

Rapid climate change is impacting water resources in Afghanistan, a country in the western Himalaya that is poorly developed in terms of scientific research and environmental monitoring. It is a semi-arid to arid country of Central Asia where livelihoods and economies have developed to be strongly dependent upon mountain water resources, and where snow- and glacier-melt delivers 80% of Afghanistan’s water supply. Rising average global temperatures and glacier shrinkage pose a significant threat to water supply. Once glaciers shrink to a certain size, “peak water” will be reached. Water supply will decline. If winter snowfall declines, or becomes more variable, glaciers are less likely to compensate for the associated water shortage that results, a process that will be compounded by continuing population growth and groundwater over-abstraction.

In order to understand the implications of glacier recession now and in the future with relative contributions of ice, snow and other components to water supply for Afghan water resources, three representative catchments were selected based on their locations and data availability. The TaqchaKhana catchment (264.4 km2 area with 3.1% glacier cover) in the north; the Sust catchment (4609 km2 area with 16% glacier cover) in the east; and the Bamyan catchment (325.3 km2 area with 0.7% glacier cover) in the center of Afghanistan. Climate and streamflow data for 2012 to 2019 obtained from Ministry of Energy and Water of Afghanistan.

In this study the glacier and snowmelt – soil contribution (GSM-SOCONT) hydrological model was modified to allow a simple representation of the effects of debris cover development on ice melt which is commonly overlooked in hydrological models of mountain water resources. The model was individually calibrated for each catchment based on Shuffled Complex Evolution Algorithm (SCE-UA), with the best parameters taken after 20,000 iterations. Eight regional climate models (RCMs) under two scenarios (2.6 and 8.5) were used in the model to simulate future streamflow in the catchments. The RCMs were bias corrected using non-parametric statistical transformation. Future glacier evolution was introduced to the model using a very simple propagation of current measured glacier recession rates into the future. After calibration on data for the periods 2012-2019 and an associated uncertainty analysis, the models were deemed sufficient to understand the relative importance of different sources to water supply and to predict future water supply. The current contributions from glacier melt were observed to be 70% for the Sust catchment, 49% for the TaqchaKhana catchment, and 11% for the Bamyan catchment. Future climate conditions initially increased the ice melt contribution for the Sust and the TaqchaKhana but reduced it for the Bamyan, confirming our hypothesis that direct effects of changing temperature and precipitation in Afghanistan are likely masked by a glacial subsidy.

How to cite: Shokory, J., Horton, P., Schaefli, B., and Lane, S.: Assessing the impact of climate change on Hydrological regime of Afghan catchments, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-15317, https://doi.org/10.5194/egusphere-egu23-15317, 2023.

EGU23-15451 | ECS | Orals | HS2.1.6

Understanding the seasonal and spatial variation of water balance in the Karnali basin in Nepal 

Pranisha Pokhrel, Jasper Griffioen, and Walter Immerzeel

The hydrology of large mountainous basins is sensitive to climate and land use change and impacts downstream availability in a diverse way. Our knowledge of the spatial and temporal variation of the water balance for large-scale mountainous basins like the Karnali (40,000 km2) is very limited.  Studies focus either on small alpine catchments or on major river basins of near continental scale. Studies focusing on the intermediate scale, where mountain water supply is directly linked to people and ecosystems downstream are scarce, but needed. In this study, we provide insight into the seasonal and spatial differences in meltwater contribution to streamflow, rain runoff, evapotranspiration and groundwater baseflow, with a particular focus on upstream-downstream dependencies. We use a high-resolution SPHY model, which we calibrate step-wise using satellite data of glacier mass balance and snow covers and observed river flow data. We explore the hydrological variability at the sub-basin scale, discuss the seasonal and spatial heterogeneity of the water balance components, and seek to understand the major drivers. Our results provide a baseline against which impacts of climate and land use changes will be assessed in a subsequent study.

How to cite: Pokhrel, P., Griffioen, J., and Immerzeel, W.: Understanding the seasonal and spatial variation of water balance in the Karnali basin in Nepal, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-15451, https://doi.org/10.5194/egusphere-egu23-15451, 2023.

EGU23-17182 | ECS | Posters on site | HS2.1.6

Sustainable water management under climate change in Southern Ecuador 

Johanna Ochoa Ruilova, María Alvarado-Carrión, Jairo Cabrera, Rolando Célleri, Patricio Crespo, Pablo Guzmán-Cárdenas, Santiago Núñez-Mejía, and Ana Ochoa-Sánchez

Global warming and changes in the magnitude and spatial distribution of precipitation have already reduced water availability in many mountain areas, including the Andes Mountain range (IPCC, 2022). Globally, approximately 2.3 billion people are currently living in highly water-stressed areas (UN Water, 2021). By the end of the century, humid and semi-humid regions would decrease by 2.3 and 4.9 %, respectively (Tabari, 2020). These scenarios, together with population and water demand increase result in (i) the water demand risks to exceed the existing capacity of water supply and (ii) the wastewater treatment infrastructure fails to treat all polluted effluent water. As such, we proposed a project to the VLIR-UOS TEAM initiatives and got funded from 2022 to 2027. Our project aims to define the effect of climate change and increasing water demand projections and to propose and develop water management strategies that will secure the water supply of Andean cities in the future.

Our study site is Cuenca, a middle-size city located in southern Ecuador and, as many Andean cities, lacks of enough data (e.g. water scarcity is uncertain on its scale and periodicity all along the region) that allows informed decision making. In this sense, this project will reduce the uncertainty of global scenarios to propose adequate bottom up adaptation strategies that lead to better water resources management at a household and
regulatory level. The objectives of the proposed project are built under the Integrated Water Resource Management approach (IWRM) and water security. During a first phase, the project will provide climate and hydrological projections in the main catchments in Cuenca for the period 2020-2050 and during the second phase, we will provide water availability projections and water management adaptation plans built with citizens and decision makers.

A priority of this project is to enhance capacity building of local governments (e.g. Municipality of Cuenca, ETAPA EP which is the local water company), national institutions and Universities; this is key to achieve the transfer of knowledge and capacity building to the partner Universities and partner institutions. Citizens and other stakeholders are also key elements for the development of this initiative. Our ultimate goal is to implement the adaptation strategies proposed during the development of this project in the plans, policies and regulations for the city, working together with the citizens in three key axes: educommunicational activities, new or additional normative proposals, and infrastructure strategies. Furthermore, there is the need to propose and evaluate climate adaptation strategies applied to Andean cities (including outside Ecuador), and thus the methodology developed in the project will be made available to those cities.

The proposed project takes environment indirectly as one of the main objectives since the development of water management strategies considering climate change and increasing water demand, will directly contribute to the improvement and stabilization of the environment. Additionally, the project considers gender balance, with a female project director in Cuenca and a 40% female presence in co-promoters and team members.

How to cite: Ochoa Ruilova, J., Alvarado-Carrión, M., Cabrera, J., Célleri, R., Crespo, P., Guzmán-Cárdenas, P., Núñez-Mejía, S., and Ochoa-Sánchez, A.: Sustainable water management under climate change in Southern Ecuador, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-17182, https://doi.org/10.5194/egusphere-egu23-17182, 2023.

EGU23-315 | Posters on site | HS2.1.7

The importance of snowmelt in the water balance of the Toconao sub-basin, Salar de Atacama 

Sonia Valdivielso, Enric Vázquez-Suñé, Juan Ignacio López Moreno, Emilio Custodio, Rotman Criollo Manjarrez, John W. Pomeroy, and Ashkan Hassanzadeh

The Salar de Atacama basin is one of the best-studied saline endorheic basins in the world due to the delicate balance between extraction of lithium-rich brine from its core, tourism, and the unique ecosystems of its surrounding lagoons. However, no study to date has quantified the contribution of snowmelt compared to rainfall in supporting groundwater recharge in the basin. In this work, satellite information (Moderate Resolution Imaging Spectroradiometer, MODIS) is used to characterize the spatial and temporal dynamics of snow coverage. However, snow equivalent water is not available from remote sensing, so the Cold Regions Hydrological Model (CRHM) was used to simulate snow water equivalent, runoff, infiltration and other hydrological processes governing the water balance and groundwater recharge. CRHM makes it possible to link physical processes to hydrological processes using hydrological response units (HRU) as control volumes for water balances and as a means of discretizing the basin. HRU were defined in the Toconao sub-basin, in the eastern part of the Salar de Atacama watershed and CRHM was parameterized from regional hydrological knowledge and run for several years, forced by reanalysis data. Special attention was paid to better understand the energy balance of snow, including sublimation and wind transport ablation losses, soil infiltration processes, and the role of snowmelt in surface runoff generation and direct and indirect groundwater recharge.

Satellite observations of snow cover recorded from 2000 to 2020 showed frequent snowfalls both in summer and winter. The greatest extent of snow cover occurred during winter, accounting for 60% of the annual snow-cover extent. Snow cover is generally located above 4500 m asl in summer, while in winter the snow cover is more extensive, covering a large part of the basin. The CRHM simulations show that the greatest amount of precipitation of the year falls as rain in the summer months with the drier winter dominated by snowfall. The intense summer rains produce the greatest annual fluxes of runoff and infiltration. In winter, snowmelt infiltration is approximately twice that from rainfall. Snow losses by wind transport and sublimation had little impact on the overall water balance despite the dry environment.

How to cite: Valdivielso, S., Vázquez-Suñé, E., López Moreno, J. I., Custodio, E., Criollo Manjarrez, R., Pomeroy, J. W., and Hassanzadeh, A.: The importance of snowmelt in the water balance of the Toconao sub-basin, Salar de Atacama, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-315, https://doi.org/10.5194/egusphere-egu23-315, 2023.

Snowmelt runoff is a significant component in the glacierized and snow-covered basins of the western Himalaya. Modelling is the most useful tool to quantify snowmelt contribution in mountainous rivers, but the paucity of in-situ observations makes the model calibration quite challenging and therefore model parameters are often adopted from the neighboring river basins. In the present study, we applied Snowmelt Runoff Model (SRM) in the Chandra-Bhaga Basin and Chhota Shigri Glacier Catchment in the western Himalaya. We systematically checked the transferability of the model parameters between the catchment and basin. Using snow cover area (SCA), precipitation, and temperature as inputs, the daily discharge for the Chhota Shigri Catchment and Chandra-Bhaga Basin was reconstructed over 2003–2018. The mean annual discharge was found as 1.2 ± 0.2 m3/s and 55.9 ± 12.1 m3/s over 2003-2018 for the Chhota Shigri Catchment and Chandra-Bhaga Basin, respectively. The discharge in the Chhota Shigri Catchment was mainly controlled by summer temperature and summer SCA, whereas in the Chandra-Bhaga Basin summer SCA and summer precipitation controlled the discharge. At both the catchment and basin scale, the decadal comparison revealed an increase (11% and 9%) and early commencement (10 days and 20 days) of the maximum monthly discharge over 2011-2018 compared to 2003-2010. In the Chhota Shigri Catchment, the model output is almost equally sensitive to the 'degree day factor' and 'runoff coefficient for snow,' but most sensitive to the 'runoff coefficient for snow' in the Chandra-Bhaga Basin. Even though the SRM parameters were calibrated in a data-rich Chhota Shigri Glacier Catchment, their application in the Chandra-Bhaga Basin led to a large discharge overestimation at the basin scale and was not transferable even in the same basin. We suggest to be cautious while adopting/transferring model parameters for SRM from other basins, particularly for the ungauged basins.

How to cite: Vinze, P. and Azam, M. F.: Evaluation of Parameter Transferability of Snowmelt Runoff Model in Chandra-Bhaga Basin, India, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-534, https://doi.org/10.5194/egusphere-egu23-534, 2023.

EGU23-1361 | Posters on site | HS2.1.7

A snow reanalysis for Italy: IT-SNOW 

Francesco Avanzi and the IT-SNOW team

Quantifying the amount of snow deposited across the landscape at any given time is the main goal of snow hydrology. Yet, answering this apparently simple question is still elusive -- particularly in complex and high-elevation terrains where data are sparse. To contribute to the advancement of snow hydrology in Mediterranean regions, we present the first serially complete and multi-year snow reanalysis for Italy (IT-SNOW). IT-SNOW covers the period from September 2010 to August 2021, with future updates envisaged on a regular basis. This reanalysis is the output of a real-time snow and glacier monitoring chain – S3M Italy -- developed for the Italian Civil Protection Department by CIMA Research Foundation. Spatial resolution is 500 m, with input data coming from thousands of weather stations across the Italian territory. By assimilating blended snow-covered area maps from Sentinel-2, MODIS, and the Eumetsat H-SAF products, as well as interpolated snow-depth maps from in-situ data, IT-SNOW optimally combines dynamic modeling and data towards reconciled estimates of snow amount and water equivalent at various scales. IT-SNOW was validated using Sentinel-1-based maps of snow depth and in-situ snow data in the Alps and the Apennines, with little bias compared to the former and typical Root Mean Square Errors of 30 to 60 cm and 90 to 300 mm for snow depth and Snow Water Equivalent, respectively. A comparison at 102 gauge stations showed a strong (0.87) correlation between peak SWE in IT-SNOW and measured annual streamflow, with snow being 22% of annual streamflow on average. IT-SNOW is freely available at the following DOI: https://doi.org/10.5281/zenodo.7034956 and we encourage users to validate and provide critical feedback for future releases.  

How to cite: Avanzi, F. and the IT-SNOW team: A snow reanalysis for Italy: IT-SNOW, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-1361, https://doi.org/10.5194/egusphere-egu23-1361, 2023.

EGU23-1557 | ECS | Posters on site | HS2.1.7

The potential use of high-resolution SWE estimates from remote sensing imagery to predict snow melt rates 

Valentina Premier, Nicola Ciapponi, Michele Bozzoli, Giacomo Bertoldi, Riccardo Rigon, Claudia Notarnicola, and Carlo Marin

Snow water equivalent is a key variable in hydrology. An accurate SWE estimation is crucial for runoff prediction, especially for catchments with strong nival regimes. Direct observations are unfortunately rare and are available only at a point scale. Accurate spatialized estimates of SWE are thus difficult to be obtained. Physically based models often suffer from the inaccuracies of input data and uncertainty of model parametrization. In this sense, the integration of traditional techniques with remote sensing observation is valuable. Although current satellite missions do not provide direct SWE observation, they allow us to extract important proxy information that is crucial for SWE reconstruction. In this sense, we propose to exploit optical and radar sensors to retrieve accurate information on the persistence of snow on the ground. In fact, the longer the persistence, the deeper the snowpack. To achieve enough spatial and temporal detail, we merged multi-scale information from MODIS, Sentinel-2, and Landsat missions. The key idea is to exploit the snow pattern persistence that we can observe with good spatial detail from Landsat and Sentinel-2 missions to reconstruct the scene when a low-resolution image (MODIS) is acquired. Furthermore, information on the duration of the melting phase can also be retrieved by exploiting the synthetic aperture radar (SAR) mounted on board of Sentinel-1. Hence, we can estimate the number of days of melting. In-situ data, when available, are also exploited in the reconstruction. In detail, air temperature is used to estimate the potential melting and the snow depth increases to determine the number of days in accumulation. The reconstruction approach is then simple: by knowing the days in melting, the total amount of melted SWE is determined. Assuming that the melted SWE is equal to the accumulated SWE, we can redistribute SWE throughout the season using a simple approach as the degree day. The final output is a daily time-series with a spatial resolution of few dozens of m. One of the major advantage of the proposed approach, compared to more traditional SWE estimation techniques, is that it does not depend from precipitation observation, often highly uncertain in high-elevation catchments. When evaluated against a reference product (i.e., Airborne Snow Observatory), the method shows a bias of -22 mm and an RMSE of 212 mm for a catchment of 970 km2 in Sierra Nevada (CA). In this work, we investigate the relationship between the melted SWE and the measured riverine discharge for a number of catchments in South Tyrol (Italy). The results may be of great interest, especially for poorly monitored basins with highly variable snow accumulation that are exploited for hydroelectric energy production. In detail, we propose a long-term analysis on SWE time-series to understand if there are evident trends that might improve hydroelectric power management.  

How to cite: Premier, V., Ciapponi, N., Bozzoli, M., Bertoldi, G., Rigon, R., Notarnicola, C., and Marin, C.: The potential use of high-resolution SWE estimates from remote sensing imagery to predict snow melt rates, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-1557, https://doi.org/10.5194/egusphere-egu23-1557, 2023.

EGU23-4012 | ECS | Orals | HS2.1.7

How well do global snow products characterize snow storage in High Mountain Asia? 

Yufei Liu, Yiwen Fang, Dongyue Li, and Steven A. Margulis

Accurate characterization of peak snow water storage is essential for assessing warm-season water availability in regions reliant on snowmelt-driven runoff. However, knowledge of peak snow water storage in data-sparse regions, such as High Mountain Asia (HMA), is still lacking due to overreliance on model-based estimates. Here, estimates of peak snow storage from eight global snow products were evaluated over HMA, using a newly developed High Mountain Asia Snow Reanalysis (HMASR) dataset as a reference. The particular focus of this work was on peak annual snow storage, as it is the first-order determinant of warm-season water supply in snow-dominated basins.

The results suggest large uncertainty in the eight global snow products in High Mountain Asia, with the climatological peak storage found to be 161 km3 ± 102 km3 across products. Compared to HMASR, most global snow products underestimate peak snow storage in HMA, with an average 33% underestimation. Large inter-product variability in cumulative snowfall (335 km3 ± 148 km3) is found to explain most of the peak snow storage uncertainty (>80%). Significant snowfall loss to ablation during accumulation season (51% ± 9%) also plays an important role in peak snow storage uncertainty, and deserves more investigation in future work.

How to cite: Liu, Y., Fang, Y., Li, D., and Margulis, S. A.: How well do global snow products characterize snow storage in High Mountain Asia?, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-4012, https://doi.org/10.5194/egusphere-egu23-4012, 2023.

EGU23-4071 | ECS | Posters on site | HS2.1.7

Long term hydrological dynamics of an Alpine glacier 

Maria Grazia Zanoni, Elisa Stella, and Alberto Bellin

Several studies have been showing that major environmental changes will occur in mountainous regions, with dramatic effects in glacierized areas. In particular, the Alps are experiencing a sharper rising in air temperature, compared to other regions. The European Alps are water towers providing fresh water to highly populated areas in a fragile environment with ecosystems and human activities that adapted to low flow and storage in winter followed by high flow in summer. This dynamic is in phase with agricultural use and touristic needs while hydropower makes use of reservoirs to allow
flexibility and increase production in the most profitable periods. Climate change may significantly impact this timing, thereby changing the scenario and introducing new challenges in water resources management.

In the present work, we comprehensively analyzed the long-term (1976-2019) meteorological and streamflow time series of a small (8.5 km2) Alpine glacierized catchment, fed by the Careser glacier, in Peio valley, Italy. A Dense Deep feed-forward Neural Network (DNN) was employed to gap-fill the daily time series of the streamflow, available since 1976. Daily temperature and monthly precipitations at the glacier were obtained by interpolating the measurements at the 32 closest meteorological stations by Kriging with the External Drift.

The resulting reconstructed time series were used to investigate the changes in streamflow from 1976. The analysis revealed that precipitation did not change significantly in the observed period. On the contrary, a statistically significant temperature increase was observed (∆T = 0.022, 0.052, 0.046 oC y−1 for the maximum, minimum and mean daily temperatures), which is, therefore, the main driver of the observed changes in the streamflow. Ablation, in terms of loss of glacier thickness, continued to increase, but the glacier’s contribution to summer runoff first increased, up to the middle of the nineties of the previous century, and successively decreased dramatically as an effect of the reduction of the glacier area. In addition, significant anticipation of the summer streamflow peak was observed in the last decade.

The proposed analysis evidenced how the rise of temperature in the Alpine region is already having a profound impact on streamflow seasonality, which is expected to exacerbate in the near future, given the projected further increase of the temperature. More from a technical point of view, the combination of classical geostatistical methods with DNN allowed a reliable reconstruction of meteorological and hydrological missing data. The algorithms developed in this study can be easily exported in other similar situations.

How to cite: Zanoni, M. G., Stella, E., and Bellin, A.: Long term hydrological dynamics of an Alpine glacier, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-4071, https://doi.org/10.5194/egusphere-egu23-4071, 2023.

EGU23-4515 | ECS | Orals | HS2.1.7 | Highlight

A glacio-hydrological perspective on the extreme year 2022 in Switzerland 

Marit Van Tiel, Matthias Huss, Massimiliano Zappa, and Daniel Farinotti

Summer 2022 broke numerous glaciological, hydrological and climatological records in Europe. Dry and warm conditions led to extreme low-water levels and problems with water supply. The hot summer in combination with little snow in winter was disastrous for the Swiss glaciers; they never lost as much volume in the century-long observational record. At the same time, this massive glacier melt meant an alleviation of the downstream hydrological drought situation. Glacier contributions to streamflow during hot and dry periods, as well as their changes due to glacier retreat are, however, poorly quantified.

In this study, we characterize the glacio-hydrometeorological extremeness of the hydrological year 2022 in Switzerland and compare it with other exceptional years in the past. Observational streamflow records from about 80 stations along glacier-fed rivers were analyzed, together with (i) temporally downscaled and spatially extrapolated glacier mass balance observations, as well as (ii) temperature and precipitation information. Results show that precipitation and temperature were exceptional, but there have been years since 1961 that were warmer or drier. However, the combined effect of low precipitation and high temperatures led to record-low summer flows throughout Switzerland, apart from the Rhone river, the upstream part of the Aare river, and a few high-elevation catchments. Catchments with a glacier cover of more than 20% even resulted in above normal summer streamflow in 2022.

The annual relative meltwater contribution from glacierized areas ranged from a few percent up to 80% of the total streamflow among the catchments and equaled up to double the mean contribution estimated for the period 1981-2010. Although 2022 glacier volume losses broke records, only a few catchments showed a record amount of glacier melt water contribution to streamflow. This may hint that for most catchments, glacier retreat is dominating the melt response to extreme warm conditions, instead of differences in the respective meteorological conditions. This process reduces the crucial capacity of glaciers to alleviate downstream drought conditions. Overall, the study highlights the need for an integrated analysis of meteorological, hydrological and glaciological data to understand the spatiotemporal dynamics of extreme dry and warm years. 

How to cite: Van Tiel, M., Huss, M., Zappa, M., and Farinotti, D.: A glacio-hydrological perspective on the extreme year 2022 in Switzerland, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-4515, https://doi.org/10.5194/egusphere-egu23-4515, 2023.

EGU23-5576 | Posters on site | HS2.1.7 | Highlight

Past and future decrease in snow in the central European rain-snow transition zone 

Michal Jenicek, Ondrej Nedelcev, Jan Hnilica, and Vaclav Sipek

Mountains are referred to as water towers because they substantially affect the hydrology of downstream areas. However, snow storages will decrease in the future due to the increase in air temperature which will affect streamflow regime and water availability. Therefore, the main objectives of our research were 1) to quantify past and future changes in snow storages for a large set of mountain catchments representing different elevations and 2) to analyse how snow responds to climate variability. The snow storage was simulated for 59 mountain catchments located in six mountain regions in Czechia for the period 1965–2019 using a bucket-type catchment model. The predictions of the future climate from EURO-CORDEX experiment were considered in the model to simulate the future change in snow.

Analyses using the Mann-Kendall test identified decreasing trends in snow storages in western parts of Czechia (by up to −45 mm per decade), while no trends were detected in eastern part of Czechia suggesting the partly different climatology of both regions. In contrast to weak trends in SWE, significant trends were documented for snow cover duration, which decreased on average by 5.5 days per decade. The reason was mostly earlier snowmelt and melt-out, while trends in snow cover onset were not identified. Nevertheless, snow responded differently to climate variables across elevations. Below 900 m a.s.l., the snow was controlled mainly by air temperature, while above 1200 m a.s.l., snow responded dominantly to changes in precipitation. With the increase in air temperature in last five decades, its importance in controlling snow storage and variability increased at all elevations.

While only some significant changes in Czechia were documented in last five decades, substantial changes are expected by the end of the 21st century, such as the decrease in annual maximum SWE by 30-75%, mainly at elevations below 1200 m a.s.l. Changes are also expected for other snow-related variables, such as snow cover duration, which will be shorter, especially due to earlier start of the melting season and thus melt-out. In general, the melt-out day is projected to occur by 30-60 days earlier compared to current conditions by the end of the century. The results also showed the large variability between individual climate projections and indicated that the increase in air temperature causing the decrease in snowfall might be partly compensated by the increase in winter precipitation. Changes in snowpack will cause the highest streamflow during melting season to occur one month earlier, in addition to lower spring runoff volumes due to lower snowmelt inputs. Additionally, the model predicted the increase in winter runoff for the future period due to the increase in air temperature and thus the shift from snowfall to rain. These changes may impose more pressure to create adaptation strategies for water reservoirs management to keep all reservoir functions, such as flood and drought protection, drinking water supply and hydropower.

How to cite: Jenicek, M., Nedelcev, O., Hnilica, J., and Sipek, V.: Past and future decrease in snow in the central European rain-snow transition zone, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-5576, https://doi.org/10.5194/egusphere-egu23-5576, 2023.

EGU23-6591 | ECS | Posters on site | HS2.1.7

Exploring the pathways of precipitation, snowmelt and glacier melt through the subsurface in high resolution, coupled, data-driven modeling experiment of the Langshisha catchment in the Himalaya 

Caroline Aubry-Wake, Lauren Somers, Varya Bazilova, Philip Kraaijenbrink, Sonu Khanal, and Walter Immerzeel

 Groundwater can be an important water source for mountain streams. To gain insights into the sources of groundwater recharge and their pathways to the downstream environments, the interactions between surface water and groundwater are investigated for the Langshisha catchment, in the Langtang basin, Nepal Himalaya. The 0.81 km2 study area ranges in elevation from 4130 to 4450 m. a.s.l., with a landscape of coarse debris, pocket meadows and moraine sediments. It is bordered on three sides by steep mountain cliffs, the Langshisha glacier outlet creek, and the Langtang river.  To simulate the hydrological behaviour of the area, we couple the glacio-hydrological model Spatial Processes in Hydrology (SPHY), a spatially distributed water balance model and the groundwater flow model MODFLOW6. We analyze three approaches to simulate the subsurface hydrology of the area:  (1) using the glacio-hydrological model alone, (2) a one-way coupling of the glacio-hydrological model with a groundwater numerical model, where the groundwater recharge from the glacio-hydrological model is used as input to the groundwater model, and (3) a two-way coupled surface water and groundwater model. The model is evaluated with in-situ field data of soil moisture, shallow groundwater levels and streamflow measurements collected intermittently over the 2013-2022 period as well as isotopic and geochemistry water sample data collected in November 2022.  Preliminary results suggest that despite the additional computational demands and time required to develop and apply a fully coupled approach, it provides essential knowledge regarding the cryosphere-surface water-groundwater interactions. Our preliminary results showcase the importance of field observations to constrain modelling efforts and will serve to guide further model applications to assess the importance of representing cryosphere-surface water-groundwater interactions in mountain landscapes. 

How to cite: Aubry-Wake, C., Somers, L., Bazilova, V., Kraaijenbrink, P., Khanal, S., and Immerzeel, W.: Exploring the pathways of precipitation, snowmelt and glacier melt through the subsurface in high resolution, coupled, data-driven modeling experiment of the Langshisha catchment in the Himalaya, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-6591, https://doi.org/10.5194/egusphere-egu23-6591, 2023.

EGU23-7664 | ECS | Orals | HS2.1.7

Surface and subsurface hydrology of a high-altitude catchment in the Trans-Himalayan region of Ladakh, India 

Mohd Soheb, Peter Bastian, Marcus Nüsser, Susanne Schmidt, Shaktiman Singh, Himanshu Kaushik, and Alagappan Ramanathan

In the cold-arid Trans-Himalayan region of Ladakh, cryospheric meltwater plays a critical role for irrigated agriculture and local livelihoods. Despite the vital importance of reliable water supply under conditions of ongoing climate change, the relative contributions from glaciers and seasonal snow cover melt, together with permafrost thaw to surface and subsurface discharge are largely unknown due to the lack of in-situ data and local hydrological modelling. This study attempts to improve the understanding of regional hydrology, based on the case study of Stok catchment, where snow and glacier meltwater feeds a village of more than 300 households. We quantified long-term (2003-2019) surface and subsurface flow using a distributed temperature index and coupled surface/subsurface flow models forced by daily in-situ, meteorological, satellite and reanalysis data. These models were calibrated with the measured discharge data from two summer periods (2018 and 2019) in order to better understand the characteristics of surface and subsurface hydrology of the catchment. We also investigated the specific contributions from the cryospheric components and from rainfall to the total flow, and water loss through sublimation. A decline in annual discharge with characteristic inter-annual variations was identified over the observation period with about half of the total accumulated flow through the subsurface. We found that snowmelt contribution was highest (~60%) followed by ice melt (~20%) and rainfall (~15%), whereas sublimation contributes to ~8% of the water loss in a hydrological year. The findings and approach of this study are important for applied hydrological studies and planning future water management strategies in the region of Ladakh.

How to cite: Soheb, M., Bastian, P., Nüsser, M., Schmidt, S., Singh, S., Kaushik, H., and Ramanathan, A.: Surface and subsurface hydrology of a high-altitude catchment in the Trans-Himalayan region of Ladakh, India, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-7664, https://doi.org/10.5194/egusphere-egu23-7664, 2023.

The water balance of high-alpine glacierized catchments is largely dominated by snow and ice processes. When modelling the hydrological response of such catchments, a reliable representation of snow/ice accumulation and melt should be ensured, especially when studying the effects of climate change. Even though numerous state-of-the-art hydrological models are able to adequately represent the contribution of snow melt into the total runoff with the use of complex approaches (e.g. energy balance models), glacier dynamics are still based on conceptual or empirical methods, which exhibit some limitations compared to more sophisticated models (e.g. explicit ice-flow dynamics).
The Water Flow and Balance Simulation Model (WaSiM) is a process-based hydrological model that includes an empirical volume-area scaling approach for describing the glacier’s evolution. Although acceptable estimates can be obtained with this approach, an integration to a more complex glacier representation is still missing. For this reason, a coupling scheme between WaSiM and the Open Global Glacier Model (OGGM) is developed, hence accounting for explicit ice-flow dynamics.
The workflow consists mainly on three steps: i) a first WaSiM run to obtain monthly values of temperature and precipitation that serve as input for the ii) second step, which is running OGGM. Finally, iii) a dynamic model run of WaSiM with the updated output from OGGM (annual glacier outlines and ice thickness) is performed. Within this last step, the glacier’s volume internally calculated by WaSiM (i.e. with the VA-scaling approach) is replaced by OGGM’s output, while performing a simultaneous multi-data set automatic calibration. In this calibration, only WaSiM parameters are adjusted and simulation results are compared against glacier mass balances (OGGM) and observed runoff. The performance of the calibration is then evaluated in terms of a weighted multi-objective function. Although the best fit between observed and simulated runoff is achieved when considering only runoff observations (single-data calibration), glacier components are better represented when calibrating the coupled model with the multi-data set (i.e. also including glacier mass balances). Therefore, a trade-off is made between general model performance and accurate runoff prediction. 
This coupling scheme is aimed for hydrological modellers with no additional expertise on glacier modelling, since OGGM is set up according to its default parameters. Finally, it could serve as a tool not only to predict the hydrological response of any glacierized catchment (even without any available glacier data), but also to make predictions under future climate projections with a more reliable representation of glaciers. 

How to cite: Pesci, M. H. and Förster, K.: Process-based water balance modelling with explicit ice-flow dynamics and multi-data set calibration: the WaSiM-OGGM coupling scheme, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-7688, https://doi.org/10.5194/egusphere-egu23-7688, 2023.

EGU23-7950 | ECS | Posters on site | HS2.1.7

Utilization of snow depth patterns to derive spatially distributed precipitation correction factors for operational hydrological modelling 

Thomas Pulka, Franziska Koch, Mathew Herrnegger, and Karsten Schulz

Simulations and information on snow cover dynamics and snowmelt in high-alpine catchments are essential for the operation of storage hydropower plants in order to predict reservoir inflow during the snowmelt season. The distribution of the seasonal snowpack is driven by the mountainous topography and vegetation, the predominant weather patterns as well as the microclimatic conditions in the area of interest. At the same time, observations of precipitation and its distribution, the basis for modelling the spatio-temporal distribution of the snowpack, are rare and error-inflicted in these regions. Especially winter precipitation is often largely underestimated in high-alpine areas. Due to the manifold and multiscale influencing factors and scarcity of measurements, the estimation of inputs for hydrological simulations in the mountains is challenging and afflicted by many uncertainties. Snow depth data in a high spatial resolution can, e.g., be obtained via terrestrial, airborne or spaceborne remote sensing techniques and can be used to support snow-hydrological modelling. Vögeli et al. (2016) showed that such snow depth maps, taken at the end of the snow accumulation period, can be utilized for precipitation scaling to significantly improve snowpack modelling in terms of spatial distribution and quantity. This study examines the benefit and challenges of precipitation scaling for enhancing reservoir inflow predictions by applying the conceptual hydrological model COSERO (Herrnegger et al., 2016). The model is computationally efficient and was successfully calibrated and validated in numerous catchments in Austria and neighbouring countries. Among other catchments, COSERO is used operationally by the hydropower operator VERBUND AG in the high-alpine headwater catchments of the Kölnbrein reservoir in the Malta Valley, the largest reservoir in Austria with a capacity of 200 million m³. The basis of our meteorological model forcings is the INCA precipitation analysis product, provided by the Austrian Central Institute for Meteorology and Geodynamics. We applied the precipitation scaling based on snow depth patterns on the INCA data in a sub-daily and sub-kilometre resolution. We investigate, if this approach leads to a more realistic representation of alpine snowpack and runoff simulated by COSERO, aiming to improve operational reservoir management.

Acknowledgements: We thank the VERBUND AG for fruitful discussions and providing us with data.

Bibliography

Herrnegger, M., Senoner, T., Nachtnebel, H.-P., 2016. Adjustment of spatio-temporal precipitation patterns in a high Alpine environment. Journal of Hydrology 556, 913–921. https://doi.org/10.1016/j.jhydrol.2016.04.068

Vögeli, C., Lehning, M., Wever, N., Bavay, M., 2016. Scaling Precipitation Input to Spatially Distributed Hydrological Models by Measured Snow Distribution. Front. Earth Sci. 4. https://doi.org/10.3389/feart.2016.00108

How to cite: Pulka, T., Koch, F., Herrnegger, M., and Schulz, K.: Utilization of snow depth patterns to derive spatially distributed precipitation correction factors for operational hydrological modelling, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-7950, https://doi.org/10.5194/egusphere-egu23-7950, 2023.

EGU23-8748 | ECS | Orals | HS2.1.7

Glacier and snow melt contributions to streamflow on James Ross Island, Antarctic Peninsula 

Ondřej Nedělčev, Michael Matějka, Kamil Láska, Zbyněk Engel, Jan Kavan, and Michal Jeníček

Antarctic Peninsula region experienced a rapid increase in air temperature during the second half of the 20th century. Although the warming was interrupted in the first decades of the 21st century, future climate projections predict that air temperature will increase significantly until the end of the 21st century in this area. Changes in air temperature have large impact on runoff process, especially in proglacial environment. Even though these changes affects both terrestrial and marine ecosystems, runoff generation in Antarctic Peninsula region is still poorly understood. Therefore, we analysed runoff process in small, partly glaciated catchment on James Ross Island, which belongs to the largest deglaciated area in Antarctica. Our objective was to 1) describe runoff variability in this area and 2) to estimate glacier, snow, and rain contributions to runoff in relation to climate variability.

Due to limited discharge measurements, we used semi-distributed bucket-type HBV model to simulate runoff process in years 2010–2020 in a daily temporal resolution. Input data for the model were time series of in situ measured air temperature, and simulated precipitation. Precipitation was simulated by the Weather Research and Forecasting model driven by ERA5 reanalysis. The HBV model was calibrated against measured daily discharge from six weeks long period in February and March 2018, and seasonal ablation measurements from years 2014–2020.

The results showed that 93% of the annual runoff occurred from October to May. The highest mean monthly runoff occurred in the second half of summer due to combination of strong glacier and snow melt. Additionally, large runoff was found in November which was caused by melt-out of seasonal snow cover. The major part (53%) of runoff originates from snow cover, 41% originates from glacier and only 6% from rainfall. Snowmelt runoff dominated during winter (with overall low absolute values of runoff) and in autumn. In summer, snowmelt runoff was almost the same as glacier runoff. In autumn, contribution of glacier to total runoff was slightly higher than contribution of snow. Contribution of snow to total runoff was higher in colder years with higher precipitation. In contrast, melting glacier contributed more during warmer years with less precipitation.

How to cite: Nedělčev, O., Matějka, M., Láska, K., Engel, Z., Kavan, J., and Jeníček, M.: Glacier and snow melt contributions to streamflow on James Ross Island, Antarctic Peninsula, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-8748, https://doi.org/10.5194/egusphere-egu23-8748, 2023.

EGU23-9243 | ECS | Orals | HS2.1.7

Adapting a snowpack model to simulate cold-based glacial hydrological processes in the McMurdo Dry Valleys, Antarctica 

Tamara Pletzer, Nicolas Cullen, Jonathan Conway, Trude Eidhammer, and Marwan Katurji

Glacial melt is the primary source of freshwater for the fragile microbial ecosystem in the McMurdo Dry Valleys (MDV) of Antarctica. These glaciers are cold-based, with internal temperatures around -18°C, however, air temperatures hover around 0°C for several weeks in the summer and föhn wind events can rapidly raise ice surface temperatures to the melting point. Thus, episodical glacial melt is sensitive to small changes in the climate.  

The aim of this research is to adapt a detailed snowpack model embedded in a distributed hydrological model to simulate the surface energy balance and run-off of a glacier in the MDV. To do this, the snowpack model in the WRF-Hydro-Crocus modelling scheme, which has been used for avalanche forecasting and temperate glaciers, is adapted to the MDV. Several modifications are made to model calculations and parameters to allow the model to successfully simulate surface energy balance and runoff in this environment. For example, the parameters for the Crocus albedo scheme are adjusted to obtain band profiles for snow, firn and ice that replicate observed albedo and remain internally consistent between surface types. The modelling system is then validated against data from an automatic weather station, eddy covariance measurements and stream discharge. It is shown to be suitable for future efforts to model the full hydrological cycle of glacial meltwater in this region.

How to cite: Pletzer, T., Cullen, N., Conway, J., Eidhammer, T., and Katurji, M.: Adapting a snowpack model to simulate cold-based glacial hydrological processes in the McMurdo Dry Valleys, Antarctica, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-9243, https://doi.org/10.5194/egusphere-egu23-9243, 2023.

EGU23-10137 | Orals | HS2.1.7

Toward a glacier retreat driven redistribution of water resources 

Michel Baraer, Bryan Mark, and Jeff McKenzie

Assessments of glacier retreat impacts on water resources are often carried out using hydrological models calibrated using stream discharge time series. Because long-term discharge measurements are scarce in different regions of the world, models’ outcomes are analyzed assuming implicitly that stream discharge evolution projections at the outlet of a watershed affect the entire drainage area following a uniform pattern. In the present study, building on the learnings from the peak water analysis we performed in 2012, we explore the heterogeneity in Rio Santa sub-watersheds responses to deglaciation. The future of water resources at each watershed is projected by applying the peak water model with the latest glacier area estimations. The resulting map of the projected water availability across the Rio Santa watershed is then overlayed with previous works and literature-based water quality and demand maps.

Results show that, while glaciers are losing their hydrological influence across the Cordillera Blanca, gaps open between water availability and demand for water at different levels of the watershed. Moreover, the dry season share of polluted sub-watersheds into the Rio Santa discharge increasing due to glacier retreat, water quality evolution will add up to the challenge of sharing an already scarce resource.

Our study suggests that deglaciation in the tropical Andes affects populations and economic activities in a complex, disparate and evolutive way. Therefore, anticipating glaciers retreat redistribution of the water resources requires integrating hydrological, chemical, biological, economic, and sociological water resources aspects in locally grounded studies.  

 

How to cite: Baraer, M., Mark, B., and McKenzie, J.: Toward a glacier retreat driven redistribution of water resources, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-10137, https://doi.org/10.5194/egusphere-egu23-10137, 2023.

EGU23-10181 | ECS | Orals | HS2.1.7

Isotopic composition as a tracer of different source contributions to stream flow in the glacierized catchments of Central Asia 

Zarina Saidaliyeva, Maria Shahgedanova, Vadim Yapiyev, Andrew Wade, Fakhriddin Akbarov, Mukhammed Esenaman, Vassiliy Kapitsa, Nikolay Kassatkin, Diliorom Kayumova, Ilkhomiddin Rakhimov, Rysbek Satylkanov, Daniyar Sayakbaev, Igor Severskiy, Maksim Petrov, Ryskul Usubaliev, and Gulomjon Umirzakov

The mountains of Central Asia are water towers servicing the arid downstream regions and maintaining irrigation and food production. There are several sources of runoff: liquid precipitation, snowpack, glacier ice, ground ice (including rock glaciers and permafrost), and ground water. The relative contributions of different water sources to stream flow are poorly quantified and its improved understanding will reduce uncertainty in hydrological modelling and projections of changes in water resources. In 2019-21, an extensive sampling programme was conducted to quantify the relative contributions of water sources to stream flow in the Tien Shan and Pamir-Alai using stable water isotope tracers (SWI) of oxygen and hydrogen. Samples of the event-based precipitation, river discharge taken daily or twice-daily at the designated sampling points and every fortnight along the river courses, and water sources were collected in the glacierized catchments in Kazakhstan (Ulken Almaty and Kishi Almaty catchments), Kyrgyzstan (Ala-Archa and Chon-Kyzyl Suu), Tajikistan (Varzob and Kafornihon), and Uzbekistan (Chirchik). The samples were processed using Picarro isotope analyser. A data set of SWI ratios from approximately 6000 samples has been produced and analysed. It is the first comprehensive SWI database in Central Asia contributing to understanding of regional and global isoscapes and water resources. The local meteoric water line (LMWL) was developed from the event-based precipitation samples. It is approximated as δD = 7.6δ18O + 8.7. The values of SWI in precipitation exhibit a clear annual cycle and depend on precipitation type (rain, snow, and mixed). The derived seasonal SWI values are different from those available from the Water Isotopes Database being nearly twice as high in winter. Snow, glacier ice and permafrost exhibit distinct isotopic signatures although these vary between the basins. Glacier ice in the Chirchik basin appears to be more depleted than elsewhere. Rock glaciers were sampled in the Ulken Almaty basin showing SWI ratios similar to those of glacier ice but both are distinct from permafrost. These results point at the feasibility of the application of the mixing model and end-member mixing analysis approaches to the partitioning of runoff and quantifying relative contributions of different water sources in the Tien Shan and Pamir-Alai. This is a policy-relevant task under the conditions of climate change.

How to cite: Saidaliyeva, Z., Shahgedanova, M., Yapiyev, V., Wade, A., Akbarov, F., Esenaman, M., Kapitsa, V., Kassatkin, N., Kayumova, D., Rakhimov, I., Satylkanov, R., Sayakbaev, D., Severskiy, I., Petrov, M., Usubaliev, R., and Umirzakov, G.: Isotopic composition as a tracer of different source contributions to stream flow in the glacierized catchments of Central Asia, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-10181, https://doi.org/10.5194/egusphere-egu23-10181, 2023.

EGU23-10420 | Orals | HS2.1.7

The value of distributed snow cover and soil moisture data for multi-objective calibration of a conceptual hydrologic model 

Rui Tong, Juraj Parajka, Fuqiang Tian, Borbála Széles, Isabella Greimeister-Pfeil, Mariette Vreugdenhil, Jürgen Komma, and Günter Blöschl

The latest advances and availability of satellite observations have great potential for improving hydrological model simulations of the water cycle. The recent study by Tong et al. (2021) showed that satellite observations of snow cover and soil moisture could improve river runoff simulations of conceptual hydrologic models with lumped model parameters. Still, the value and potential of spatial patterns of satellite observations for hydrologic model parametrization need to be better understood. This study aims to evaluate and compare different multiple-objective calibration strategies that use model inputs and satellite observations for the model calibration in lumped, spatially distributed and stepwise ways. We aim to test the potential of daily MODIS (Moderate Resolution Imaging Spectroradiometer) snow cover and ASCAT (Advanced Scatterometer) soil water index images observed over 204 Austrian catchments in 2000-2014. Results show that stepwise calibration strategies that first calibrate the snow model parameters to satellite snow cover data followed by calibrating the remaining model parameters outperform (particularly in lowlands) the classical calibration strategies estimating model parameters in one single calibration step. The use of distributed snow cover and soil moisture patterns in model calibration improves the snow and soil moisture simulation performance of the model. The use of MODIS snow cover data has a more significant contribution to the overall improvement in model performance than ASCAT soil moisture data.

 

References:

Tong, R., Parajka, J., Salentinig, A., Pfeil, I., Komma, J., Széles, B., Kubáň, M., Valent, P., Vreugdenhil, M., Wagner, W., and Blöschl, G.: The value of ASCAT soil moisture and MODIS snow cover data for calibrating a conceptual hydrologic model, Hydrol. Earth Syst. Sci., 25, 1389-1410, 10.5194/hess-25-1389-2021, 2021.

How to cite: Tong, R., Parajka, J., Tian, F., Széles, B., Greimeister-Pfeil, I., Vreugdenhil, M., Komma, J., and Blöschl, G.: The value of distributed snow cover and soil moisture data for multi-objective calibration of a conceptual hydrologic model, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-10420, https://doi.org/10.5194/egusphere-egu23-10420, 2023.

EGU23-10634 | Orals | HS2.1.7

Development of an operational snow energy balance model informed by numerical weather prediction and remote sensing for the Western United States 

McKenzie Skiles, Joachim Meyer, Dillon Ragar, Patrick Kormos, and Andrew Hedrick

The Colorado River, which supplies water to the Western United States (WUS) and Mexico, is fed primarily from snow melting out of the Rocky Mountains. Currently, snowmelt contribution to streamflow is forecast using a calibrated temperature index model (SNOW-17). This approach is simple, and computationally efficient, but loses efficacy when snow conditions are outside the calibration period as temperature index models do not represent all of the physical processes that control accumulation and melt rates. For example, in the southern headwaters of the Colorado River forecasting errors have been related to surface darkening and accelerated melt following episodic dust on snow events. Here, we present an ongoing project to develop and mature a spatially distributed snow energy balance model, informed with numerical weather prediction (NWP) and remote sensing, to support operational decision making. This effort is a collaboration between the University of Utah's Snow Hydrology Research to Operations (Snow HydRO) Laboratory, the USDA-ARS Northwest Watershed Research Center (NWRC), and the Colorado Basin River Forecast Center (CBRFC). The model, iSnobal, is forced with the High Resolution Rapid Refresh (HRRR) NWP and is assessed against in situ observations and snow depth maps from the Airborne Snow Observatory in representative headwater basins. Initial testing of the HRRR-iSnobal combination showed that it can simulate snow accumulation, in terms of both patterns and magnitude, but that snowmelt rates were too slow. This was attributed to inaccurate radiation balance, specifically shortwave radiation due to the traditional treatment of net shortwave, including a 'time since snowfall' albedo decay curve. To account for spatial and temporal variability in snow albedo, daily observations from the spatially and temporally complete MODIS fractional snow products (MODSCAG+MODDRFS) were incorporated to update net solar radiation inputs. The updates were tested in different ways including direct albedo updates, direct decay curve component updates, and basin specific calibration decay curves. Although all remote sensing based update approaches improved snowmelt timing, direct updates had the greatest improvement in years with more intense snow darkening. This presentation will include a summary of current results, updates on incorporation into operational forecasting, and highlight plans for future developments.

How to cite: Skiles, M., Meyer, J., Ragar, D., Kormos, P., and Hedrick, A.: Development of an operational snow energy balance model informed by numerical weather prediction and remote sensing for the Western United States, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-10634, https://doi.org/10.5194/egusphere-egu23-10634, 2023.

EGU23-11164 | Orals | HS2.1.7 | Highlight

Glaciers’ role as water resource in the Swiss Alps 

Daniel Farinotti, Aaron Cremona, Marit van Tiel, and Matthias Huss

In high-mountain environments such as the European Alps, glaciers are an important component of the water cycle. With ongoing climate change, this role seems in jeopardy though: glaciers in Switzerland, for example, have lost more than 30% of their volume since the year 2000, and future projections indicate a future with ice-free landscapes if society was to fail in taking immediate and stringent climate action.

In this contribution, the role of glaciers as water resource will be reviewed. By taking the Swiss Alps as an example, their contribution to regional water supplies and usage will be quantified. A focus will be on the glaciers’ role in providing water during dry periods, as well as the relevance of glacier melt in the context of hydropower production.

Based on both extended glaciological measurements collected in the frame of the Glacier Monitoring Switzerland (GLAMOS) program and daily glacier melt data retrieved through automated methods, we will for example quantify the meltwater contribution that glaciers had in the extremely hot summer 2022. The year saw a record-high 6% glacier volume loss and we show that individual heat waves contributed over-proportionally to this amount: 35% of the total summer ice loss, for example, occurred in the 25 hottest days, delivering a water amount that corresponds to 56% of the total summer melt seen on average for the past decade.

Such phases of extreme melt can also be challenging for water resource management. In high-alpine rivers, where annual glacier contributions to streamflow were up to 80% in 2022, existing hydropower infrastructure can for example be overwhelmed. For a country that sees some 2.1kWh of hydro-electricity being produced for every cubic meter of glacier melt, this raises questions about future management strategies, and calls for robust projections of future streamflow.

How to cite: Farinotti, D., Cremona, A., van Tiel, M., and Huss, M.: Glaciers’ role as water resource in the Swiss Alps, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-11164, https://doi.org/10.5194/egusphere-egu23-11164, 2023.

Alpine glaciated catchments are rapidly changing with glacier retreat. Combined with future earlier snow melt and more liquid precipitation, the importance of high alpine catchments to provide essential water resources for downstream uses will increase. In this context, groundwater storage may play a critical role in maintaining baseflow during drought events. In this study, we provide an overview of the hydrogeological functioning of the Otemma glacier catchment, a typical glaciated catchment in the Swiss Alps. Based on three years of field data, we provide a complete conceptual model of the volumes and timescales at which different landforms store and release water and compare those results with a catchment-scale analysis of the winter discharge recession. Based on water isotopes and geochemical data, we show the strong spatial heterogeneity in the water sources that recharge those landforms and how they are interconnected. Finally, we present results of a 3D model of the groundwater-surface water interactions in the proglacial outwash plain, discuss where potential new floodplains may form in the future and show a rather limited potential storage of the order of 20 mm. We conclude that superficial landforms have a limited potential to provide significant baseflow for downstream users but can provide significant moisture for high alpine ecosystems. Nevertheless, we show that bedrock infiltration likely represents the largest groundwater reservoir but more research is needed to characterize its role in the future.

How to cite: Müller, T., Lane, S. N., and Schaefli, B.: Characterizing the current and future groundwater storages in a highly glaciated catchment : a synthesis of 3 years of field observations and modelling results, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-11831, https://doi.org/10.5194/egusphere-egu23-11831, 2023.

EGU23-13841 | Posters on site | HS2.1.7

Discharge characteristics for different glacier mass balance conditions at Vernagtferner, Ötztal Alps 

Astrid Lambrecht and Christoph Mayer

Discharge from glaciers plays an important role for ecosystems, land use and hydropower production in different regions of the world. The discharge hydrograph in glaciated catchments is determined by several parameters, like snow cover, glacier size and glacier mass balance, besides others. Variations in these parameters might considerably change the temporal availability of melt water in such regions, which needs to be taken into account for long term water management planning.

Here, we investigate in detail the characteristics of discharge in a highly glaciated catchment in the central eastern Alps. The Vernagtferner basin (11 km² area and 6.9 km² glacier area) is characterised by a high density of monitoring stations, which are an ideal basis for testing and applying models of snow and glacier evolution, as well as discharge simulations. The combination of a gauging station with meteorological observations and continuous monitoring of snow and ice melt at different locations, allows to investigate the major processes in detail. During the period 2019 to 2022 rather different mass balance conditions occurred, which strongly influenced the temporal evolution of the discharge generation. We investigate the significance of snow cover, firn and glacier ice to the melt water generation and the temporal characteristics of the hydrograph.

How to cite: Lambrecht, A. and Mayer, C.: Discharge characteristics for different glacier mass balance conditions at Vernagtferner, Ötztal Alps, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-13841, https://doi.org/10.5194/egusphere-egu23-13841, 2023.

EGU23-13878 | ECS | Posters on site | HS2.1.7

Linking detailed canopy structure and snow process model representations to explore the dynamics of snowpack properties and ground conditions 

Giulia Mazzotti, Jari-Pekka Nousu, Tobias Jonas, and Matthieu Lafaysse

A large portion of boreal and alpine forests of the Northern Hemisphere hosts seasonal snowpacks over multiple months of the year. Rising temperatures and forest disturbances are causing rapid change to these environments; therefore, accurate prediction of forest snow is relevant for a variety of disciplines such as biogeochemistry, ecohydrology, cryospheric, and climate sciences. Research in each of these fields relies on process-based models that are usually discipline-specific, e.g., snow hydrology and land surface models. These models are intended for a broad range of spatiotemporal scales and consequently include canopy and snowpack process representations of varying complexity. Detailed snow physics models that resolve the microstructure of individual snow layers, motivated by avalanche forecasting and snow remote sensing, have existed for years. More recent advances in forest snow process representation and increasing availability of high-resolution canopy structure datasets have led to the development of snow-hydrology models capable of resolving tree-scale processes.

Here, we introduce a new model system that combines concepts from two such sophisticated models: the snowpack representation from Crocus, and the canopy representation from the Flexible Snow Model. We present multi-year simulations at 2-m resolution across sub-alpine and boreal forest landscapes. Spatially explicit simulations allow us to assess the spatio-temporal dynamics of snow properties, ground conditions and land surface states, and to unravel their distinct dependencies on canopy structure heterogeneities at a previously unfeasible level of detail. This work aims to inform and further promote the use of process-based modelling tools in interdisciplinary ecosystem research at the interface between snow and ecosystem science, and in support of environmental change impact studies, management practices and mitigation/adaptation strategies.

How to cite: Mazzotti, G., Nousu, J.-P., Jonas, T., and Lafaysse, M.: Linking detailed canopy structure and snow process model representations to explore the dynamics of snowpack properties and ground conditions, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-13878, https://doi.org/10.5194/egusphere-egu23-13878, 2023.

EGU23-14338 | ECS | Orals | HS2.1.7

Influence of sun cups on surface albedo of wet Alpine snowpack 

Francesca Carletti, Loïc Brouet, Michael Lehning, and Mathias Bavay

In high elevation Alpine areas, characterised by high snow accumulation and radiation-driven melt processes, the formation of peculiar ablation features called sun cups can be observed. Sun cups likely influence the energy and mass balance of the wet snowpack by locally reducing the snow albedo, leading to an enhanced ablation in the hollows. To our knowledge, these phenomena are to date poorly explored in the literature and little to no attempts have yet been made to study their evolution in time and correlate them with meteorological forcings and energy fluxes over the wet snowpack.

The dynamics of the sun cups was investigated at the high elevation Alpine site of Weissfluhjoch (Davos, Switzerland) over the Spring of 2022. At the site, the snow surface was mapped on an hourly basis by means of a fixed, automated high-resolution 3D terrestrial laser scanner. Snow height maps were obtained by processing the registered point clouds.

Sun cups were individually and automatically detected over the snow surface maps by a delineation algorithm in Python. The evolution of sun cups in time was studied with respect to their maximum depth and cross-section.

The maximum depth and cross-section evolution of sun cups showed a high correlation with the measured albedo, especially when they are fully-formed. This finding suggests that peculiar snow surface formations that can be detected by means of remote sensing systems can give valuable additional information about the ongoing processes within the wet snowpack, paving the way to a radar-assisted modelling of the snowmelt dynamics. In an era of increasing concern over the availability of water resources, a better understanding and modelling of snowmelt dynamics is of major importance, especially in remote areas where accurate predictions are required for operational purposes (e.g. hydropower and irrigation).

How to cite: Carletti, F., Brouet, L., Lehning, M., and Bavay, M.: Influence of sun cups on surface albedo of wet Alpine snowpack, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-14338, https://doi.org/10.5194/egusphere-egu23-14338, 2023.

EGU23-15485 | ECS | Posters on site | HS2.1.7

The use of snow fences for snow conservation 

Philip Crivelli

With ongoing climate change, residual snow in the mountains is disappearing ever earlier each year. This reduces their potential to be used as a water source later in the year. Especially for infrastructures like mountain huts, this can lead to severe problems. Our study describes how to actively apply the basics of snowdrift fences as snow-farming to establish snow depots as summer water source. This project asses how drifting snow can be applied in a practical and sustainable way in alpine terrain without the use of snow-groomers or snow-cannons.

Existing, scientific models of snow transport are utilized in conjunction with the fundamentals of snow fence design to maximize the yield of residual snow in complex alpine terrain, contributing to water supply security. The study presents the results and approaches to the implementation of CFD modelling integrating meteo and snowpack models to analyze mountain terrain for potential sites. These results form the basis for the use of snowdrift fences to increase water storage in mountain regions.

How to cite: Crivelli, P.: The use of snow fences for snow conservation, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-15485, https://doi.org/10.5194/egusphere-egu23-15485, 2023.

After several decades of climate change impact studies on high alpine environments, the hydrological community has come to a good agreement on how cryosphere-dominated streamflow regimes will evolve in the future. And observed streamflow regime trends largely confirm existing predictions for Alpine environments. Many of these predictions are based on models that lack a detailed representation of hydrological processes that occur below the snowpack or the ice-cover; these model focus on the representation of snow accumulation and snow and ice-melt and use simply methods to transform liquid water input into streamflow.

However, the gradual reduction of snow cover duration might significantly affect streamflow generation processes in Alpine environments, e.g. via the evolution of spatial and temporal patterns of groundwater recharge or of hydrologic connectivity and of the related seasonal stream network structure.  

In this presentation, we will synthesize what we learned about the interaction of the cryosphere with streamflow generation from our multiyear process studies in two high Alpine catchments in Western Switzerland, the Vallon de Nant and the Otemma glacier catchment. We elaborate perspectives for future field work but also for hydrological model development.

How to cite: Schaefli, B. and Ceperley, N.: When snow and ice are gone: beyond hydrological regime changes,  what are the nuts and bolts of future streamflow generation processes?, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-15908, https://doi.org/10.5194/egusphere-egu23-15908, 2023.

EGU23-16153 | Posters on site | HS2.1.7

Water budget in the Rutor glacier area: results from multidisciplinary activities 

Stefania Tamea, Elisabetta Corte, and Carlo Camporeale

Due to global warming and glacial retreat, periglacial areas and headwater catchments are experiencing relevant changes in surface processes and in water budgets. The water cycle, altered by the changing snow accumulation/melting dynamics, ice ablation, higher altitude increasing rainfalls frequencies, is shifting towards larger average and peak runoff productions. These alterations have also an impact on sediment production, on geomorphological processes, on ecosystem dynamics. The goal of our research is to take advantage of multidisciplinary activities aimed at monitoring the glacial and peri-glacial area of the Rutor glacier, in the Aosta valley (north-western Italian Alps) to quantify its dynamics under climate change. The Rutor glacier is fast-retreating and has a terminus that moved more than 2 km since the mid-19th century: it is thus a perfect case study to investigate snow/ice dynamics and runoff production, considering also that the periglacial area is characterized by a number of lakes and channels that collect and convey the melt water, while dynamically responding to it. In this work, we present the results from a multidisciplinary collaboration that involves hydrologists, geophysicists, geomatics and water engineers with the goal of monitoring stream flows, water properties, lake water balance and runoff production. Thanks to the contribution of different disciplines, we could gain an advanced quantitative knowledge of the water budget in the area that will represent a starting point for further investigations of processes and interactions within this unique melting landscape.

How to cite: Tamea, S., Corte, E., and Camporeale, C.: Water budget in the Rutor glacier area: results from multidisciplinary activities, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-16153, https://doi.org/10.5194/egusphere-egu23-16153, 2023.

EGU23-16657 | ECS | Orals | HS2.1.7

Relationship between rainfall and flood frequency curves in high elevation areas 

Giulia Evangelista, Irene Monforte, Marco Demateis Raveri, and Pierluigi Claps

Flood hazard assessment and its relationship with extreme rainfall probabilities is a well-addressed topic in the literature, but not enough in mountain areas, where the climate change effect can hit much more than in other physical contexts. In mountain basins, the lack of systematic data and the complexity of the rain/snow phenomena make investigations even more necessary to figure out the consequences of global warming.

This study explores how the partial contributing area effect due to snow accumulation, on the one hand, and the basin runoff coefficient, on the other hand, shape the relationship between rainfall and flood probabilities in high elevation areas. To this aim, the FloodAlp geomorphoclimatic model (Allamano P. et al., 2009) is used.

The model is based on the derived distribution approach, producing as a result a simplified flood frequency curve based on the intra-annual variability of the portion of the catchment area covered by snow, according to simple descriptions of the seasonal variation of the freezing elevation and of the hypsographic curve of the basin.

To model the basin hypsometric features, we propose the use of a two-parameter Strahler function, which is a more accurate and alternative formulation to the simple one-parameter function originally used in the model. The role of the extreme rainfall frequency analysis is also explicitly analysed, by applying the model using rainfall extremes recorded both in the daily and 24-hours windows. In this application, the only parameter that requires calibration is the runoff coefficient. Considering recordings of annual maximum daily discharges, the runoff coefficients for more than 100 gauged basins in north-western Italy have been calibrated. Comparisons are then possible between the shapes of rainfall and flood frequency distributions within the sample analysed, that also take into account the basin geomorphoclimatic features. Results of this application address the selection of relevant characteristics in relation to the impact of climate change on mountain floods as a result of changes in temperatures and in the statistics of rainfall extremes.

 

How to cite: Evangelista, G., Monforte, I., Demateis Raveri, M., and Claps, P.: Relationship between rainfall and flood frequency curves in high elevation areas, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-16657, https://doi.org/10.5194/egusphere-egu23-16657, 2023.

EGU23-614 | ECS | PICO | HS2.1.8

A New Lumped Descriptor of Basin-Wide Hydrological Connectivity 

Francesco Dell'Aira and Claudio I. Meier

In their efforts to study the rainfall-runoff conversion process, hydrologists have deployed a variety of approaches. Despite the huge range of methodologies, a general theme can be identified: there is a trade-off between how generalizable a model can be across different basins and the degree of detail in basin characterization. On one hand, regionalization approaches and deep-learning models use lumped information, typically covering some combination of average geometric, topographic, land-cover, and climatic characteristics of a basin. Based on these descriptors, some general, typically empirical relationship is derived to explain the hydrological response of any watershed within a homogeneous region, e.g., by fitting a regional equation to predict the 10-yr flood at ungauged locations, or by developing regional statistical models on the pooled, standardized data from all the hydrologically similar basins. On the other hand, distributed, physically-based models attempt to simulate the water exchanges occurring within a catchment at different spatial and time scales, at the cost of a detailed, spatially-explicit basin characterization, with the resulting lack of transferability to other watersheds.

While a lumped characterization of basins is crucial for a variety of approaches aimed at model transferability, such as regionalization techniques for flood prediction or deep learning models for flood forecasting, most procedures only consider basin-averaged properties or at most their distribution. Thus, they are unable to account for hydrological connectivity, even though it is well known that it has strong effects on a watershed’s response. For example, the percentage of impervious area is often used as a proxy for the level of urbanization in catchments, but it cannot provide any information about how urbanized areas are located with respect to each other and the watershed outlet, although different spatial configurations of these may result in different hydrological behaviors, for the same precipitation input.

We propose a new, lumped hydrological connectivity index that can incorporate information on how different parts of a basin, with their various topographic and land-use characteristics, are connected to each other and the stream network. In this way, we incorporate their relative contributions to the hydrologic response of the watershed, depending on their location. This index can be regarded as a condensed measure of the potential that each location has for generating runoff at the watershed outlet, given spatially-explicit characterizations of its properties. It can be used in synergy with other lumped descriptors to provide a more detailed basin characterization that reflects hydrological connectivity.

We test the predictive power of the proposed index in the framework of regional flood frequency analysis finding that it benefits well-established approaches for hydrological prediction in ungauged basins.

How to cite: Dell'Aira, F. and Meier, C. I.: A New Lumped Descriptor of Basin-Wide Hydrological Connectivity, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-614, https://doi.org/10.5194/egusphere-egu23-614, 2023.

EGU23-789 | ECS | PICO | HS2.1.8

Hydro-climatic shifts of worldwide river basins in the past century 

Muhammad Ibrahim, Miriam Coenders, Ruud Van der Ent, and Markus Markus Hrachowitz

Understanding of river basins hydro-climatic shifts and their drivers in the past is of significant importance for the prediction of future projections. This study evaluates the hydro-climatic shifts of worldwide river basins through Budyko Framework at 20 years’ time steps from 1901 to 2000 based on field-measured runoff data. It is also aimed to identify whether shifts are related to climate change, human interventions, or both. The selected river basins cover a wide range of climates and topography. The movement of basins in the Budyko Space is quantified from the first twenty years to the next twenty years. It is found that 47% of the catchments observed an increase in their aridity and evaporative indices between a period of comparison from 1901 to 1920 and 1921 to 1940. An increase in both indices means that these catchments have moved toward a drier state and more precipitation is partitioned into evaporation as compared to runoff. However, it is observed that during periods from 1961 to 1980 & 1981 to 2000 this percentage has reduced to 20% only and more number of catchments (47%) have observed a decrease in the aridity index as well as the evaporative index. It is seen that major hydro-climatic shifts of river basins have occurred from an increase in aridity and evaporative indices to a decrease in both indices from start to the end of the past century. It is concluded that with time, more number of catchments have moved towards a wet state and observed an increase in runoff as compared to the past. Although, more catchments observed a shift but the magnitude of movement is not that much high for all of them. It is observed that the catchments with a high aridity and evaporative index are more sensitive to change. On average for all time periods of comparison, it is found that for 90% of the catchments the climate change is the main driver of hydro-climatic shifts and the change for the remaining is caused by combined effects of climate and human interventions. This understanding of hydroclimatic shifts of river basins over time can be helpful for water management practices, especially for the catchments which are sensitive to change and also have observed an increase in runoff.

How to cite: Ibrahim, M., Coenders, M., Van der Ent, R., and Markus Hrachowitz, M.: Hydro-climatic shifts of worldwide river basins in the past century, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-789, https://doi.org/10.5194/egusphere-egu23-789, 2023.

EGU23-1404 | PICO | HS2.1.8

Evaluating the seasonal non-stationarity in the Wei River Basin 

Xin Yuan and Fiachra O'Loughlin

Due to the impact of changing climate and human activities on hydrology, non-stationary research is becoming more popular. In the Wei River Basin, which is the largest tributary of the Yellow River, non-stationary has been studied for decades and has found non-stationary signals in discharge and precipitation records. However, these studies have mainly focused on the annual time series and ignored the seasonal signal.

In this study, to investigate the non-stationarity more comprehensively, two non-stationary tests have been applied including the Mann-Kendall test and the Heuristic segmentation algorithm. These tests were applied to runoff time series from 12 catchments and catchment averaged precipitation and temperature time series derived from 114 meteorological stations. Like other studies, our results, show that on the annual timescale, non-stationary signals (multiple change points and decreasing trends) are found in the runoff time series on most catchments along the mainstem, while the runoff time series of the Beiluo catchment does not show any non-stationarity signal. However, our results show that there is clearly a seasonal difference with change points occurring at contrasting times. Among all time series, about 40% show only single nonstationary signals (trend or change point), while the remainder exhibit multiple signals indicating the importance of using multiple tests. While the results show that non-stationary signals exist in all time series, further work is needed to quantify if or to what level are meteorological variables the driver of non-stationary signals in the runoff time series.  

How to cite: Yuan, X. and O'Loughlin, F.: Evaluating the seasonal non-stationarity in the Wei River Basin, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-1404, https://doi.org/10.5194/egusphere-egu23-1404, 2023.

EGU23-2650 | ECS | PICO | HS2.1.8

CAMELS-spat: catchment data for spatially distributed large-sample hydrology 

Wouter Knoben and Martyn Clark

The recent publication of large-sample datasets for hydrologic modeling and analysis has led to a revival of comparative hydrology. The “CAMELS” branch of these datasets currently provide catchment attributes and meteorological time series for basins located in the United States, Chile, Brazil, Australia and Great-Britain, with a dataset for France under development. A key characteristic of these datasets is that information is provided as catchment-averaged data; i.e. each catchment is treated as a lumped entity with no spatial variability. Some progress is being made to extend large-sample hydrology to include spatially distributed data, most notably by the recent LamaH dataset which covers part of Central Europe.

Here we present progress on developing a continental domain dataset for large-sample hydrology intended for spatially distributed modeling and analysis. Our domain covers the United States and Canada, expanding both geographically and climatically on the region covered by the LamaH dataset. We focus mostly on relatively undisturbed headwater catchments, because accurate data on water management policies and infrastructure can be difficult to obtain. Our aim is to provide the necessary data for process-based modeling and analysis at a sub-daily temporal resolution. 

How to cite: Knoben, W. and Clark, M.: CAMELS-spat: catchment data for spatially distributed large-sample hydrology, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-2650, https://doi.org/10.5194/egusphere-egu23-2650, 2023.

EGU23-5256 | ECS | PICO | HS2.1.8

Caravan - A global community dataset for large-sample hydrology 

Frederik Kratzert, Grey Nearing, Nans Addor, Tyler Erickson, Martin Gauch, Oren Gilon, Lukas Gudmundsson, Avinatan Hassidim, Daniel Klotz, Sella Nevo, Guy Shalev, and Yossi Matias

High-quality datasets are essential to support hydrological science and modeling. Several datasets exist for specific countries or regions (e.g. the various CAMELS datasets). However, these datasets lack standardization, which makes global studies difficult. Additionally, creating large-sample datasets is a time and resource consuming task, often preventing the release of data that would otherwise be open. Caravan (as in “a series of camels”) is an initiative that tries to solve both of these problems by creating an open data processing environment in the cloud for the community to use.

Caravan is a globally consistent and open dataset

Caravan leverages globally available data sources that are published under an open license to derive meteorological forcings and attributes for any catchment. We use ERA5-Land for meteorological forcings and hydrological reference states (SWE and four levels of soil moisture) and HydroATLAS for the catchment attributes. Currently, Caravan consists of 6830 gauges with daily streamflow data (median record length ~30 years), 9 meteorological variables (from 1981 - 2020) in different daily aggregations, 4 hydrological reference states, and a total of 221 catchment attributes.

Caravan is derived entirely in the cloud

All meteorological time series (and hydrological reference states) from ERA5-Land are processed on Google Earth Engine, which removes the burden of downloading and processing large amounts of raw gridded data. Similarly, all catchment attributes are computed on Earth Engine. The code used to derive Caravan is publicly available (https://github.com/kratzert/Caravan/) . Once you have streamflow records and the corresponding catchment polygons, deriving all other data (forcing data and attributes) is a matter of a few hours of actual work. Depending on the number of catchments, their size and spatial distribution, that are being processed at once on Earth Engine , it might take a day or two for Earth Engine to extract meteorological data and catchment attributes. 

Most importantly: Caravan is a community project

Even though the existing data in Caravan has good coverage over most climate zones, the spatial coverage is still patchy. Here is where we see Caravan as a community effort. Given the provided code, everybody with access to streamflow data and the authorisation to redistribute it can create a Caravan extension with minimal effort and share the extension with the community, thus contributing to a dynamically growing dataset. A full step-by-step tutorial is available at https://github.com/kratzert/Caravan/wiki. We envision that, with many people participating, this will result in a truly global and spatially consistent, large-sample hydrology dataset. A first Caravan extension was already published by Julian Koch (https://zenodo.org/record/7396466), which increased the number of gauges to 7138, by adding 308 gauges in Denmark.

How to cite: Kratzert, F., Nearing, G., Addor, N., Erickson, T., Gauch, M., Gilon, O., Gudmundsson, L., Hassidim, A., Klotz, D., Nevo, S., Shalev, G., and Matias, Y.: Caravan - A global community dataset for large-sample hydrology, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-5256, https://doi.org/10.5194/egusphere-egu23-5256, 2023.

EGU23-5492 | ECS | PICO | HS2.1.8

Estimating the parameters of a flood forecasting model: with or without updating procedures? 

Paul C. Astagneau, François Bourgin, Vazken Andréassian, and Charles Perrin

When they are used for operational forecasting, hydrological models are almost always combined with some kind of updating procedures. Then a question arises: should the model parameters be calibrated with or without the updating procedures? Calibrating with the updating procedures often improves forecast efficiency, but it can also lead to parameter inconsistency and ultimately to a drop in performance in some cases.

In this study, we evaluate the pros and cons of making the parameters of a flood forecasting model vary with lead times. We investigate the dependencies of the model parameters to the lead times and determine where and when this procedure significantly improves forecast quality. A modified version of the GR5H hydrological model is used on 229 French catchments where 10,652 events were selected. The model is run at the hourly time step and combined with a simple updating procedure to produce forecasts at four lead times. The model parameters were estimated from a large screening of the parameter space (3 million runs for each catchment). Results show that the parameters related to fast catchment processes are the most dependant on lead times, indicating the need for more specific parameter estimation methods when modelling catchments prone to flash floods.

How to cite: Astagneau, P. C., Bourgin, F., Andréassian, V., and Perrin, C.: Estimating the parameters of a flood forecasting model: with or without updating procedures?, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-5492, https://doi.org/10.5194/egusphere-egu23-5492, 2023.

EGU23-7302 | ECS | PICO | HS2.1.8

Lag in catchment vegetation response to water availability and atmospheric dryness 

Guta Wakbulcho Abeshu and Hong-Yi Li

Catchment water availability for vegetation use (i.e., catchment wetness) and atmospheric water demand (i.e., vapor pressure deficit, VPD) are two of the major abiotic factors that control the intra-annual variability of catchment vegetation carbon uptake (i.e., GPP). This study analyzes 380 catchments distributed across the contagious US to explore the causality and interconnectedness between these two factors and catchment vegetation productivity. We use indices to represent seasonal climatic, hydrologic, and vegetation characteristics: Horton Index (HI), ecological aridity index (EAI), evaporative fraction index (EFI), and carbon uptake efficiency (CUE). Further, we employ statistical methods, including circularity statistics, spearman's correlation, Granger's causality, and PCMCI+, to depict connections between catchment wetness, atmospheric dryness, and vegetation carbon uptake. Our results indicate that catchment water supply-productivity and water demand-productivity cause-effect relations occur within a maximum span of two months (i.e., ±1 month from GPP). The annual scale relationships of these variables are more likely driven by a few dominant months. Moreover, attributed to the lag, hysteresis exists between GPP and catchment wetness and between GPP and VPD. The narrowest hysteresis develops in dry catchments (i.e., HI→1, EFI→1, and CUE have low intra-annual variability), and the wide hysteresis develops in catchments where HI and EFI have strong intra-annual variability, and their seasonal patterns are not in phase. For catchments that are not permanently under water-limited or energy-limited conditions, vegetation is under hydrologic stress (i.e., high HI) during the peak growing period. GPP is at its highest in this period, and CUE is out of phase with HI and in phase with EFI. These findings support the need for developing a direct functional framework between catchment water supply, atmospheric demand, and vegetation productivity. Such a framework can help us track normal and extreme hydrologic and climatic signals' effect on catchment vegetation and vice versa.

How to cite: Abeshu, G. W. and Li, H.-Y.: Lag in catchment vegetation response to water availability and atmospheric dryness, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-7302, https://doi.org/10.5194/egusphere-egu23-7302, 2023.

EGU23-9640 | PICO | HS2.1.8

Automated classification of the German soil map (BUEK 200) into FOOTPRINT soil types and its parameterization for hydrological modelling 

Stefan Reichenberger, Thorsten Pohlert, Qianwen He, Sebastian Gebler, Sebastian Multsch, and Beate Erzgraeber

The FOOTPRINT Soil Type (FST) system has been derived during the FOOTPRINT project (2006-2009) to facilitate spatially distributed hydrological and solute transport modelling at national or EU scale. The basic idea of this approach is to classify the soil typological units (STUs) of a national or European soil database into a limited number of soil types (FSTs) in order to reduce the number of unique soil-climate combinations for the later numerically expensive simulations. The FST code consists of a hydrological class (the FOOTPRINT Hydrologic Group), a topsoil and a subsoil texture code and an organic matter profile code. The FST system is model-independent, but complete parameterization methodologies were established during FOOTPRINT for MACRO, a 1-D dual permeability model for simulating water flow and solute transport in macroporous soils at field level. In this study we i) translated the latest version of the German soil map 1:200,000 (BUEK200) into FSTs, ii) derived representative profiles for all FSTs with arable land use, and iii) parameterized these representative profiles in MACRO. The 3648 STUs with arable land use in the BUEK200 were classified into 226 FSTs. Area proportions covered by the different FSTs are highly skewed: The 13 FSTs with the largest areas already cover 50 % of the total arable land. The hydrological class of each FST indicates whether artificial drainage is needed to allow arable landuse, and a map of potentially drained arable land was derived for Germany accordingly. A representative soil profile was established for every FST by depth-based averaging over all soil profiles belonging to the same FST. Special care had to be taken to ensure that mineral soil layers were not mixed with peat or hard rock layers. The plausibility of the representative FST profiles and their MACRO parameterization was checked with water balance simulations. The present case study for the BUEK200 soil database demonstrates the potential of the FST system for spatially distributed hydrological and solute transport modelling at large scale based on national soil databases.

How to cite: Reichenberger, S., Pohlert, T., He, Q., Gebler, S., Multsch, S., and Erzgraeber, B.: Automated classification of the German soil map (BUEK 200) into FOOTPRINT soil types and its parameterization for hydrological modelling, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-9640, https://doi.org/10.5194/egusphere-egu23-9640, 2023.

EGU23-10031 | ECS | PICO | HS2.1.8

A comprehensive global analysis of the spatiotemporal variability of Land Surface Temperature 

Laura Torres-Rojas and Nathaniel W. Chaney

Land surface temperature (LST) is a crucial state variable determining the interactions between the land surface and the atmosphere (i.e., energy, water, and carbon fluxes). Accordingly, several hydrological quantities, such as soil moisture content, vegetation water stress, gross primary production, and crop yield, correlate strongly with it. Thus, LST constitutes a critical variable in understanding the physics of multiple land surface processes. Decades of global satellite remotely sensed fields are now available, creating an unprecedented opportunity to understand better the LST spatiotemporal variability by diagnosing its spatial and temporal persistence, deriving spatial and temporal correlation lengths, identifying areas with similar spatiotemporal patterns, and determining the physical factors influencing this variability from regional to global scales. This presentation will address this gap in understanding by comprehensively analyzing the spatiotemporal variability of LST globally. Preliminary work regarding this topic has been performed using the

As part of our evaluation, we will first derive the Empirical Spatio-Temporal Covariance Functions (ESTCFs) for the global ~5x5 km Copernicus LST hourly product. A 1x1-arcdegree moving window will be defined over the globe to compute the ESTCFs, and an hourly time step between 2010 and 2022 will be used for the analysis. The analysis will focus exclusively on the daytime of summer months because spatial heterogeneity of LST will play the most significant role in summertime (e.g., daytime summer convection). To summarize the obtained ESTCFs, a parametric spatiotemporal covariance function model will be fit to each 1x1-arcdegree ESTCF. From this parametric fit, we will evaluate the persistence of the patterns, analyze the spatial and temporal correlation lengths, and evaluate the space-time interaction displayed for different locations. Additionally, clustering analysis will be applied directly to the derived parametric covariance functions to identify functionally similar areas. Finally, we will compare the derived empirical covariance functions to well-known factors spatiotemporal influencing LST variabilities such as land cover, surface thermal properties, topography, incoming solar radiation, and meteorological conditions.

How to cite: Torres-Rojas, L. and Chaney, N. W.: A comprehensive global analysis of the spatiotemporal variability of Land Surface Temperature, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-10031, https://doi.org/10.5194/egusphere-egu23-10031, 2023.

EGU23-10294 | ECS | PICO | HS2.1.8

Large Sample Basin Attribute Generation and Interpretation 

Dan Kovacek and Steven Weijs

In recent years several large-sample hydrometeorological datasets have been developed and used as inputs in both process-based and machine learning hydrological models, often for runoff prediction in ungauged basins.  Large sample hydrology datasets take information from a rapidly evolving array of geospatial data sources to create indices describing basin attributes associated with runoff-generating processes.  

In this study we discuss nuances of computational representation of basins, attribute interpretation with respect to physical processes, attributes vs. applications, the rate of change of spatial information sources, and the rapid growth and use of open source software tools.  Preliminary findings from generating a large sample dataset of ungauged basin attributes (~1M basins) are presented to support convergence towards standardized computational methods for basin attribute selection and calculation.

How to cite: Kovacek, D. and Weijs, S.: Large Sample Basin Attribute Generation and Interpretation, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-10294, https://doi.org/10.5194/egusphere-egu23-10294, 2023.

EGU23-10344 | PICO | HS2.1.8

Interpretable Unsupervised Classification of River Catchments with Network Science 

Fabio Ciulla and Charuleka Varadharajan

The classification of river catchments has been an active field of study for decades and the recent surge in hydrological and environmental datasets promotes the formulation of new approaches to this endeavor. We present a novel method for catchment classification based on physical traits similarity using network science, where the relationship among the catchments is represented by the edges of a network. Under this framework we leverage the capability of networks to capture collective behaviors to find clusters of catchments with similar physical traits. The use of networks allows the adoption of similarity metrics other than the common euclidean distance, which is subjected to quality degradation in high dimensions but is still required in many traditional clustering algorithms. Also, a network of traits is built to investigate their similarity patterns and condense this information into a small number of interpretable traits categories. Such categories are used to provide a characterization of each cluster of catchments. The method has been tested on over 9000 river catchments across the contiguous United States, each one accompanied by traits such as climate or vegetation coverage, and anthropogenic features such as land use or proximity to developed areas. The resulting classification shows a remarkable geographical coherence supported by the characteristic traits categories. Additionally, we find that when hydrological indices (like statistics on streamflow or water temperature) are aggregated according to the clusters of catchments, different clusters show different hydrologic behaviors. This, along with the information from cluster characterization, allows us to establish a connection between hydrological behaviors and physical traits. Finally, this framework can be applied at multiple scales, from continental to regional. When tested on a regional scale, the method automatically modifies the network topology to reflect the traits patterns relevant to the area under investigation.

How to cite: Ciulla, F. and Varadharajan, C.: Interpretable Unsupervised Classification of River Catchments with Network Science, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-10344, https://doi.org/10.5194/egusphere-egu23-10344, 2023.

EGU23-13916 | ECS | PICO | HS2.1.8

Demonstrating the importance of streamflow observation uncertainty when evaluating and comparing hydrological models 

Jerom Aerts, Jannis Hoch, Gemma Coxon, Nick van de Giesen, and Rolf Hut

Large-sample hydrology datasets provide an excellent test-bed for evaluating and comparing hydrological models. The validity of the results from studies that use large-sample hydrology datasets, however, can be undermined when observation uncertainty is not taken into account in the analyses. The differences between model simulations might well be within the observation uncertainty bounds and are, therefore, inconclusive on model performance.

To this end, we highlight the importance of including streamflow observation uncertainty when conducting hydrological evaluation and model comparison experiments based on the CAMELS-GB dataset (Coxon et al., 2015) . We introduce a generic flexible workflow that accounts for streamflow observation uncertainty, but is also applicable for other sources of observation uncertainty. This workflow is implemented in the ‘FAIR by design’ eWaterCycle platform (Hut et al., 2022). 

Two experiments are conducted to demonstrate the effect that streamflow observation uncertainty has on large-sample dataset based conclusions. The first experiment is an inter-model comparison experiment of the distributed PCR-GLOBWB and wflow_sbm hydrological models (Hoch et al. (2022) & van Verseveld et al. (2022)). The second experiment is an inner-model evaluation of the impact of additional streamflow based calibration on the results of the distributed wflow_sbm hydrological model. For the latter we found that approximately one third of the catchment simulations resulted in model differences that fell within the bounds of streamflow observation uncertainty.

How to cite: Aerts, J., Hoch, J., Coxon, G., van de Giesen, N., and Hut, R.: Demonstrating the importance of streamflow observation uncertainty when evaluating and comparing hydrological models, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-13916, https://doi.org/10.5194/egusphere-egu23-13916, 2023.

EGU23-14357 | ECS | PICO | HS2.1.8

CAMELS-SAX: A meteorological and hydrological dataset for spatially distributed modeling of catchments in Saxony 

Corina Hauffe, Clara Brandes, Kan Lei, Sofie Pahner, Philipp Körner, Rico Kronenberg, and Niels Schuetze

Comparative hydrology has been found to deepen our understanding of hydrological processes in catchments and helps to improve the proper evaluation of hydrological models. Recently, the global hydrological community has developed a series of publicly available, large-scale  „CAMELS“-datasets that provide catchment attributes and meteorological time series of catchments on a national level. These datasets include catchment-averaged values of catchment characteristics and meteorological time series and therefore allow only lumped modeling. In this study, we introduce a new dataset "CAMELS-SAX" for large-sample studies in the region of Saxony (Germany), which has a high diversity and heterogeneity of catchment attributes, such as geology and land use. "CAMELS-SAX" consists of meteorological and hydrological time series covering 60 years of data on a daily timestep for more than 200 catchments. The dataset includes spatially distributed catchment attributes and covers an area of about 23.000 km² with undisturbed and anthropogenic-influenced catchments ranging from 1 km² up to 5.000 km², which can be used for spatially distributed modelling. We will provide the standardized dataset for the German Federal State of Saxony for studies evaluating distributed models' performance on a smaller spatial scale. In the presentation, we show an overview of catchment attributes, time series, and hydrological signatures for the subset of undisturbed catchments. In addition, we present the results of a sensitivity analysis of the hydrological behavior caused by climate change.

How to cite: Hauffe, C., Brandes, C., Lei, K., Pahner, S., Körner, P., Kronenberg, R., and Schuetze, N.: CAMELS-SAX: A meteorological and hydrological dataset for spatially distributed modeling of catchments in Saxony, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-14357, https://doi.org/10.5194/egusphere-egu23-14357, 2023.

EGU23-15001 | ECS | PICO | HS2.1.8

Analysis and attribution of the hydrological coherence of gridded precipitation and temperature datasets in the Italian Alpine Region 

Andrea Galletti, Diego Avesani, Alberto Bellin, and Bruno Majone

Large-scale hydrological modeling has gained a wealth of attention in the last decades, due to the importance of assessing the growing anthropogenic and climate change impacts on water resources. In the context of these studies, the Alpine Region has historically played a key role, being widely recognized as “Europe’s water tower” and given the complex combination of anthropogenic and climatic drivers influencing its hydrology. The application of hydrological modeling at the synoptic scale requires an accurate assessment of the climatic forcing, chiefly precipitation and temperature. Nowadays, a number of observation-derived gridded products providing precipitation and temperature over a regular grid are available to benchmark and support large-scale analyses. However, these products are often not tailored to potential hydrological applications and are based on data with different and often uncertain levels of accuracy and resolution. In this context, assessing the uncertainty due to the climatic forcing and its relationship with the hydrological response of different catchments becomes crucial in order to gain confidence in the simulations. In the present study, we analyze the ability of several gridded datasets (which are best suited to large-scale analyses) to reproduce observed streamflows of more than 200 reaches across the Italian Alps. The simulations have been conducted by feeding HYPERstreamHS, a distributed hydrological model specifically tailored for large-scale simulations, with the following gridded meteorological datasets: MESAN, COSMO reanalysis, APGD, MSWEP, E-OBS, MESCAN, and ERA5-Land. Hydrological coherence was first evaluated by means of the NSE and KGE efficiency indexes. Then, we attempted to break down the main drivers of hydrological coherence by classifying the analyzed catchments based on hydrological and geomorphological characteristics, and by analyzing the relative incidence on the uncertainty of temperature and precipitation, by means of ANOVA.

How to cite: Galletti, A., Avesani, D., Bellin, A., and Majone, B.: Analysis and attribution of the hydrological coherence of gridded precipitation and temperature datasets in the Italian Alpine Region, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-15001, https://doi.org/10.5194/egusphere-egu23-15001, 2023.

EGU23-17151 | PICO | HS2.1.8

Spatial variability and temporal changes of drought generation processes over Europe and the Alps 

Anne Van Loon, Manuela Brunner, and Jonas Götte

Hydrological extreme events are generated by different sequences of hydro-meteorological drivers, the importance of which may vary within the sample of drought events and in space and time. Here, we investigate how the importance of different hydro-meteorological driver sequences varies by event magnitude, in space, and in time using large samples of catchments in Europe and the Alps. To do so, we develop an automated classification scheme for streamflow drought events, which assigns events to one of eight drought event types - each characterized by a set of single or compounding drivers. Our results show that (1) moderate droughts are mainly driven by rainfall deficits while severe events are mainly driven by snowmelt deficits; (2) rainfall deficit droughts and cold snow season droughts are the dominant drought event type in Western Europe and in Eastern and Northern Europe, respectively; (3) temporal changes in both drought intensity, deficit, and duration and generation processes are stronger in high- than in low-elevation catchments; and (4) in high-elevation catchments, snowmelt-deficit-induced droughts become more frequent, leading to increases in drought deficits. We conclude that climate impact assessments on droughts can profit from assessing changes in drought generation processes to improve the understanding of how drought magnitudes are changing in a warming world.

How to cite: Van Loon, A., Brunner, M., and Götte, J.: Spatial variability and temporal changes of drought generation processes over Europe and the Alps, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-17151, https://doi.org/10.5194/egusphere-egu23-17151, 2023.

HS2.2 – From observations to concepts to models (in catchment hydrology)

EGU23-344 | ECS | Posters on site | HS2.2.1

An information-theoretic approach for evaluating catchment scale process relationships 

Gowri Reghunath and Pradeep P. Mujumdar

Hydrological responses of a catchment evolve due to the complex interactions between various climate inputs and landscape characteristics. Such interactions and the resulting hydrological processes need to be adequately understood to explicitly describe the catchment’s behaviour and process dynamics. Hydrological modelling serves as a powerful tool to strengthen the understanding of such complex process interactions. Conventional hydrological modelling practices focus on calibrating the model outputs with an aim only to match the observed discharge at stream gauge locations. This procedure might not adequately capture the process interactions and the underlying causalities, especially in catchments exhibiting strong non-linear hydrological process relationships. While getting the streamflow right, there is a chance that the other hydrological processes may be wrongly captured, i.e., getting the right calibration results for the wrong reasons. In this study, information-theoretic measures such as Shannon Entropy, Mutual Information and Transfer Entropy are used to understand the process relationships simulated using a physically based hydrological model. The grid-based Variable Infiltration Capacity (VIC) model is employed at a spatial resolution of 0.25 x 0.25-degree over the Cauvery river basin in peninsular India at a daily time scale. Entropy measures are applied to the major hydrological processes such as rainfall, surface runoff, actual evapotranspiration and baseflow, which are simulated using the model, and their relationships are evaluated using non-linear correlation metrics. The study also proposes an entropy-based calibration framework for improving the model efficiency in simulating the catchment water balance. This work highlights the advantages of using information-theoretic measures over conventional methods in evaluating hydrological process relationships, especially in catchments manifesting strong non-linear hydrological behaviour.

How to cite: Reghunath, G. and Mujumdar, P. P.: An information-theoretic approach for evaluating catchment scale process relationships, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-344, https://doi.org/10.5194/egusphere-egu23-344, 2023.

EGU23-403 | ECS | Posters on site | HS2.2.1

Development of an hourly hydrological model for Great Britain 

qianyu zha, Yi He, and Timothy Osborn

Assessment of climate change impacts on flooding risks has been undertaken by using hydrological models calibrated at a daily time step and driven by daily outputs from the global or regional climate models. However, the daily scale model typically underestimates the magnitude of floods. A model run at a higher temporal resolution can be more capable of capturing flood peaks and hence more representative of the expected future flood magnitude (Beylich et al., 2021; Huang et al., 2019). This study aims to develop an hourly HBV hydrological model for Great Britain. The precipitation observations at an hourly time step for Great Britain [CEH-GEAR1hr] (Lewis et al., 2022) were used to calibrate the hourly HBV model. The model was also calibrated using daily observations from HadUK-Grid dataset (Hollis et al., 2019). The CAMELS-GB catchments in Great Britain (Coxon et al., 2020) were selected as the study area. Hourly time series of flow data were obtained from Environment Agency (EA) for England, Scottish Environment Protection Agency (SEPA) for Scotland and Natural Resources Wales (NRW) for Wales. Daily flow data are from National River Flow Archive (NRFA). The calibrating objective function for the HBV hydrological model at both daily and hourly time steps is Nash–Sutcliffe efficiency (NSE) (Nash and Sutcliffe, 1970), and also the modified Kling-Gupta efficiency (KGE), the ratio of the root-mean-square error to the standard deviation (RSR)  and Pearson's correlation coefficient (r) were used to compare. For the daily model, more than 77% and 35% of the CAMELS-GB catchments achieve NSE values over 0.6 and 0.8, respectively. The hourly model performance is comparable with the daily model and the hourly model outperforms the daily model in capturing the peak flows.

References
Beylich, M., Haberlandt, U., Reinstorf, F., 2021. Daily vs. hourly simulation for estimating future flood peaks in mesoscale catchments. Hydrol. Res. 52, 821–833. 
Coxon, G., Addor, N., Bloomfield, J.P., Freer, J., Fry, M., Hannaford, J., Howden, N.J.K., Lane, R., Lewis, M., Robinson, E.L., Wagener, T., Woods, R., 2020. CAMELS-GB: hydrometeorological time series and landscape attributes for 671 catchments in Great Britain. Earth Syst. Sci. Data 12, 2459–2483. 
Hollis, D., McCarthy, M., Kendon, M., Legg, T., Simpson, I., 2019. HadUK‐Grid—A new UK dataset of gridded climate observations. Geosci. Data J. 6, 151–159. 
Huang, Y., Bárdossy, A., Zhang, K., 2019. Sensitivity of hydrological models to temporal and spatial resolutions of rainfall data. Hydrol. Earth Syst. Sci. 23, 2647–2663. 
Lewis, E., Quinn, N., Blenkinsop, S., Fowler, H.J., Freer, J., Tanguy, M., Hitt, O., Coxon, G., Bates, P., Woods, R., Fry, M., Chevuturi, A., Swain, O., White, S.M., 2022. Gridded estimates of hourly areal rainfall for Great Britain 1990-2016 [CEH-GEAR1hr] v2.
Nash, J.E., Sutcliffe, J.V., 1970. River flow forecasting through conceptual models part I — A discussion of principles. J. Hydrol. 10, 282–290. 

 

How to cite: zha, Q., He, Y., and Osborn, T.: Development of an hourly hydrological model for Great Britain, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-403, https://doi.org/10.5194/egusphere-egu23-403, 2023.

EGU23-1369 | ECS | Orals | HS2.2.1

Physics-based hydrological modeling of the joint variations of stream network length and catchment discharge 

Francesca Zanetti, Gianluca Botter, and Matteo Camporese

Understanding the spatiotemporal dynamics of runoff generation in headwater streams is crucial for better characterizing catchment functioning under current and projected climatic conditions. In this context, experimental data on the expansion and contraction of the stream network can be especially valuable. These data can be gathered exploiting different tools and techniques, from visual surveys to cameras, from remote sensing to electrical conductivity probes. New available data are often used to study joint variations of active stream length and discharge at the catchment outlet and allowed the scientific community to derive general laws for describing and interpreting such complex behavior. However, field mapping is highly time consuming, e.g. because the instruments deployed required an intense supervision to ensure the reliability of the data collected. Using physically based numerical models to simulate the spatial configuration of the wet channels and the corresponding catchment discharge thus represents a promising application. In this study, we used CATHY (CATchment HYdrology), an integrated surface–subsurface hydrological model, to study event-based dynamics of catchment discharge and active stream network in two synthetic catchments with pre-defined geological characteristics (hydraulic conductivity, porosity, water retention curve, depth to bedrock) and different morphometric properties (shape and slope). We run a set of simulations under time-variant conditions and under steady state conditions for different levels of catchment wetness and we analyzed the emerging relationship between total active length (L) and outlet discharge (Q). The numerical simulations were used to investigate the role of topography, climate and morphology on the dynamics of L and Q, and the ensuing L(Q) relationship. Numerical models can be a valuable tool for investigating the internal dynamics of the soil moisture that eventually drives the joint changes of river network length and discharge in response to precipitation.

How to cite: Zanetti, F., Botter, G., and Camporese, M.: Physics-based hydrological modeling of the joint variations of stream network length and catchment discharge, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-1369, https://doi.org/10.5194/egusphere-egu23-1369, 2023.

EGU23-2314 | ECS | Posters on site | HS2.2.1

An analytical generalization of Budyko framework with physical accounts of climate seasonality and water storage capacity 

Xu Zhang, Jinbao Li, Qianjin Dong, and Ross A. Woods

The Budyko framework is an effective and widely used method for describing long-term water balance in large catchments. However, it only considers the limits of water and energy in evaporation (E), and ignores the impacts of climate seasonality and water storage capacity (Sc), resulting in errors for Mediterranean climate and catchments with small Sc. Here we combined the Ponce-Shetty model with Budyko hypothesis, and analytically generalized Budyko framework with physical accounts of climate seasonality and Sc. Precipitation (P), potential evaporation (PE), and Sc are used to represent the limits of water, energy, and space for E, respectively. Our results show that previous Budyko-type equations can be treated as special cases of generalized Budyko-type equations with uniform P and PE and infinite Sc. The new generalized equations capture the observed decrease in E due to asynchronous P and PE and small Sc, and perform better than the Budyko-type equations with varying parameters in the contiguous United States with fewer parameters. Overall, our generalization of Budyko framework improves the robustness and accuracy for estimating mean annual E with the aid of physical interpretation, and will facilitate water balance assessment at regional to global scales.

How to cite: Zhang, X., Li, J., Dong, Q., and Woods, R. A.: An analytical generalization of Budyko framework with physical accounts of climate seasonality and water storage capacity, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-2314, https://doi.org/10.5194/egusphere-egu23-2314, 2023.

EGU23-4281 | ECS | Posters on site | HS2.2.1

Hourly model simulation to improve the estimation of extreme floods in small catchments in Western Germany 

Li Han, Björn Guse, Dung Nguyen, Oldrich Rakovec, Xiaoxiang Guan, Sergiy Vorogushyn, Luis Samaniego, and Bruno Merz

The July 2021 flood in Western Germany is one of the most severe flood events in small-scale catchments during the past decades. It has led to life loss and severe damage in the Ahr, Erft, and Rur basins. The BMBF-funded joint project KAHR (https://hochwasser-kahr.de) deals with the effects of this flood and develops scientific knowledge to assist the reconstruction process. To analyze past floods and develop future flood management strategies, there is a need for small-scale flood modeling with finer spatial-temporal resolution in this area. Based on the derived simulated floods, we can investigate the spatiotemporal patterns of extreme weather and associated meteorological and hydrological conditions that could lead to similar or more significant flood events.

This study uses the mesoscale hydrological model mHM at hourly resolution for three small catchments Ahr, Erft, and Rur. This is one of the first applications of mHM forced with hourly meteorological forcing data and should enable more accurate processes and representation of such extreme floods. In a further step, a regional weather generator and a disaggregation procedure are applied to generate 10,000 years of synthetic hourly meteorological data for the Ahr, Erft, and Rur catchments. These data are used to create long time series of discharge with the calibrated mHM model. This enables the investigation of extreme floods and the assessment of flood risk under future climate conditions.

How to cite: Han, L., Guse, B., Nguyen, D., Rakovec, O., Guan, X., Vorogushyn, S., Samaniego, L., and Merz, B.: Hourly model simulation to improve the estimation of extreme floods in small catchments in Western Germany, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-4281, https://doi.org/10.5194/egusphere-egu23-4281, 2023.

EGU23-4911 | ECS | Orals | HS2.2.1

Satellite-based soil moisture could enhance the reliability of agro-hydrological modeling in large transboundary river basins 

Mohammad Reza Eini, Christian Massari, and Mikołaj Piniewski

Satellite-based observations of soil moisture, leaf area index, precipitation, and evapotranspiration facilitate agro-hydrological modeling thanks to the spatially distributed information. In this study, the Climate Change Initiative Soil Moisture dataset (CCI SM, a product of the European Space Agency (ESA)) adjusted based on Soil Water Index (SWI) was used as an additional (in relation to discharge) observed dataset in agro-hydrological modeling over a large-scale transboundary river basin (Odra River Basin) in the Baltic Sea region. This basin is located in Central Europe within Poland, Czech Republic, and Germany and drains into the Baltic Sea. The Soil and Water Assessment Tool+ (SWAT+) model was selected for agro-hydrological modeling, and measured data from 26 river discharge stations and soil moisture from CCI SM (for topsoil and entire soil profile) over 1476 sub-basins were used in model calibration for the period 1997-2019. Kling–Gupta efficiency (KGE) and SPAtial EFficiency (SPAEF) indices were chosen as objective functions for runoff and soil moisture calibration, respectively. Two calibration strategies were compared: one involving only river discharge data (single-objective - SO), and the second one involving river discharge and satellite-based soil moisture (multi-objective – MO). In the SO approach, the average KGE for discharge was above 0.60, whereas in the MO approach, it increased to 0.67.The SPAEF values showed that SWAT+ has acceptable accuracy in soil moisture simulations. Moreover, crop yield assessments showed that MO calibration also increases the crop yield simulation accuracy. The results show that in this transboundary river basin, adding satellite-based soil moisture into the calibration process could improve the accuracy and consistency of agro-hydrological modeling.

How to cite: Eini, M. R., Massari, C., and Piniewski, M.: Satellite-based soil moisture could enhance the reliability of agro-hydrological modeling in large transboundary river basins, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-4911, https://doi.org/10.5194/egusphere-egu23-4911, 2023.

EGU23-5579 | ECS | Posters on site | HS2.2.1

Developing generic reservoir operating rules for inclusion in the national-scale hydrological modelling of Great Britain 

Saskia Salwey, Gemma Coxon, Francesca Pianosi, Rosanna Lane, Michael Bliss Singer, and Chris Hutton

To meet growing water demand and to satisfy an increasing population, reservoirs are continually being integrated into river systems across the world. The presence of a reservoir can dictate the downstream flow regime, such that in many locations, understanding reservoir operations can be crucial to understanding the hydrological functioning of an impacted catchment. Consequently, over the last two decades, correctly representing reservoirs, and their operations, in hydrological modelling frameworks has become a key area of research for simulating water availability. Although substantial progress has been made in modelling reservoir operations (which control how water volumes are distributed across space and time), there is still no consensus on the best way to define, calibrate and evaluate operating rules within hydrological models. In most locations, data describing reservoir operating rules are not available, and timeseries of reservoir inflow, outflow and storage are often unpublished. Consequently, modelers must simplify and generalize sets of release rules from very little information, particularly where they are to be applied across large scales (e.g. across hundreds of reservoirs). Generic reservoir operating rules have typically been tested and developed using the Global Reservoir and Dam (GranD) database and thus are biased towards large irrigation reservoirs (which make up the majority of the dataset). Whilst operating rules have also been tested across many hydropower and multipurpose reservoirs, a gap remains for the definition of generic reservoir operating rules designed for smaller water supply reservoirs that can be applied nationally in countries such as Great Britain (GB).

In this study, we integrate a new generic reservoir simulation component into a national-scale hydrological model of Great Britain and compare simulation results from two modelling scenarios (with and without the new reservoir component). The first scenario, where reservoirs are omitted, is used as a benchmark representative of current modelling practices in GB (where none of the national-scale hydrological models include reservoirs), whilst the second uses a set of generic operating rules focused on simulating small, water resource reservoirs. In both scenarios, we use Multiscale Parameter Regionalisation (MPR) for model calibration. To assess the suitability of our operating rules for simulating future conditions and evaluating water availability during hydrological extremes, we test the consistency of model performance across the onset, duration and recovery from droughts. This study will demonstrate the importance of including reservoir representation in hydrological models of Great Britain, and will introduce a set of operating rules suitable for smaller reservoirs with a focus on water supply.

How to cite: Salwey, S., Coxon, G., Pianosi, F., Lane, R., Bliss Singer, M., and Hutton, C.: Developing generic reservoir operating rules for inclusion in the national-scale hydrological modelling of Great Britain, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-5579, https://doi.org/10.5194/egusphere-egu23-5579, 2023.

EGU23-6075 | ECS | Posters on site | HS2.2.1

Global validation of the SoilClim soil moisture estimates using in-situ and remote sensing observations 

Marketa Podebradska, Milan Fischer, Jan Balek, and Miroslav Trnka

Soil moisture is a key factor for plant growth and agricultural production. Therefore, it has become a fundamental part of agricultural drought monitoring systems developed for various spatial scales ranging from local to regional and global. Despite the development of large-scale soil moisture monitoring systems, in-situ soil moisture observations still remain inadequate for precise soil moisture monitoring, especially in remote areas, where there is a limited number of monitoring stations. Together with remote sensing technologies soil moisture modeling may provide an alternative to in-situ measurements that delivers spatially continuous estimates over large geographic areas. SoilClim is a semi-empirical water balance model that, together with other outputs (e.g., reference and actual evapotranspiration, soil temperature), estimates daily soil moisture in various depths of soil profile. The model has previously been validated on a total of 20 sites (5 in Central Europe and 15 in central USA) and is now used for global monitoring and prediction of soil moisture and drought intensity in an operational and interactive web platform (www.windy.com). Our study evaluates the SoilClim soil moisture global measurements with 0.1° spatial resolution using two independent sources of information: i) in-situ soil moisture measurements from the International Soil Moisture Network, and ii) the soil moisture derived from the Metop ASCAT sensors on Metop-A and Metop-B satellites. In the conference presentation we will introduce the SoilClim model and present results of the global validation including statistical spatial analysis and triple collocation.

Acknowledgement: This study was conducted with support of SustES - Adaptation strategies for sustainable ecosystem services and food security under adverse environmental conditions (CZ.02.1.01/0.0/0.0/16_019/0000797).

How to cite: Podebradska, M., Fischer, M., Balek, J., and Trnka, M.: Global validation of the SoilClim soil moisture estimates using in-situ and remote sensing observations, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-6075, https://doi.org/10.5194/egusphere-egu23-6075, 2023.

EGU23-7358 | ECS | Posters on site | HS2.2.1

Flow intermittence prediction using a hybrid hydrological modelling approach: a guide to reducing uncertainty related to observed intermittence data 

Louise Mimeau, Annika Künne, Flora Branger, Sven Kralisch, Alexandre Devers, and Jean-Philippe Vidal

Rivers are rich in biodiversity and act as ecological corridors for plant and animal species. With climate change and increasing anthropogenic water demand, more frequent and prolonged periods of drying in river systems are expected, endangering biodiversity and river ecosystems. However, understanding and predicting the hydrological mechanisms that control periodic drying and rewetting in rivers is challenging due to a lack of studies and hydrological observations, particularly in non-perennial rivers.

Within the framework of the Horizon 2020 DRYvER (Drying River Networks and Climate Change) project, a hydrological modelling study of flow intermittence in rivers is being carried out in 6 European catchments (Croatia, Spain, Finland, France, Hungary, Czech Republic) characterized by different climate, geology and anthropogenic use. The objective of this study is to represent the spatio-temporal dynamics of flow intermittence at the reach level in meso-scaled river networks (between 200 km² and 350 km²). The daily and spatially distributed flow condition (flowing or dry) is predicted using the J2000 distributed hydrological model coupled with a Random Forest classification model. Observed flow condition data from different sources (water level measurements, photo traps, water temperature measurements, citizen science applications) are used to build the predictive model. In this study we aim to evaluate the impact of the observed flow condition dataset (sample size, spatial and temporal representativeness) on the performance of the predictive model.

Results show that the hybrid modelling approach developed in this study allows to predict precisely the spatio-temporal patterns of drying in the 6 catchments. This study shows the value of combining different sources of observed flow condition data to reduce the uncertainty in predicting flow intermittence.

How to cite: Mimeau, L., Künne, A., Branger, F., Kralisch, S., Devers, A., and Vidal, J.-P.: Flow intermittence prediction using a hybrid hydrological modelling approach: a guide to reducing uncertainty related to observed intermittence data, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-7358, https://doi.org/10.5194/egusphere-egu23-7358, 2023.

EGU23-7472 | Orals | HS2.2.1 | Highlight

Recent progress in land surface models related to the hydrological cycle 

Matthias Cuntz

What is the difference between a hydrologic model and a land surface model (LSM)? While hydrologic models concentrate on water fluxes and stores, LSMs describe the coupled energy, water and carbon cycles. There are also little conceptual LSMs so that they can best be compared to so-called process-based hydrologic models. Quite a few of the LSMs were developed as part of Earth System Models. Their primary output variables are hence the exchange fluxes with the atmosphere and they are often operated on continental to global scale, which implies very coarse spatial resolutions compared to hydrologic models.

Here I will describe how state-of-the-art LSMs describe the water fluxes and how the fluxes are evaluated. I will outline current developments in the LSM community, focusing on the developments related to the hydrologic cycle. I will discuss current trends amongst developers of LSMs and problems that originate from these trends. I will also point to the challenges that come from ever increasing model resolutions. I will discuss in this context the scaling issue of, for example, soil parameters and how specific choices lead to problems in other parts of the LSM.

How to cite: Cuntz, M.: Recent progress in land surface models related to the hydrological cycle, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-7472, https://doi.org/10.5194/egusphere-egu23-7472, 2023.

EGU23-7622 | Orals | HS2.2.1

Modelling Infiltration and Infiltration Excess: The Importance of Fast and Local Processes 

Axel Bronstert, Daniel Niehoff, and Gerd R. Schiffler

A major aim of physically based distributed hydrological models is an adequate representation of hydrological processes, including runoff generation processes. A significant proportion of runoff is generated through the subsurface, i.e. by groundwater flow or unsaturated subsurface stormflow. However, in the case of high rainfall intensity and/or low soil-surface infiltrability, surface runoff may strongly contribute to total runoff, too, either through saturation excess (“Dunne-type surface runoff”) or infiltration excess (“Hortonian surface runoff”). Both types of surface runoff can be rather important if antecedent wetness is high and parts of the catchment area are saturated (leading to saturation excess), or if the maximum infiltration rate into the soil surface is less than the actual rainfall intensity (resulting in infiltration excess). Even though the latter process can be very important during high-intensity rainstorms, both for flood generation and for matter transport linked with surface runoff, an appropriate consideration of this process in catchment models is still challenging. Actually, budgeting between the actual rainfall intensity and the soil surface infiltration capacity is required. This may appear simple in principle, but there are a number of challenges in the details: First, the ‘real’ rainfall intensity may vary tremendously in time increments much smaller than the time step of the model. The soil surface infiltrability can also be significantly reduced, e.g. by crusting, compaction or rain energy-induced sealing of the soil surface or through hydrophobic effects.

Otherwise, soil infiltrability can be strongly enhanced as a consequence of preferential flow paths / macropores caused by e.g. bioturbations or other voids.

Finally, there is high variability of such soil surface features appearing at a rather small spatial scale, below the typical spatial modelling unit.

This contribution presents observational data and model approaches to deal with these challenges. We show results from combined infiltration and infiltration-excess experiments and observations at three different spatial scales. Then, we present a model approach based on a double-porosity soil, thus enabling the combined modelling of high infiltration rates and dampened soil moisture distribution after termination of infiltration, as observable in the field. Furthermore, we present an approach to model the effects of soil surface conditions on actual infiltration capacity and its variation.

We show simulation results where these approaches improved the overall plausibility and explanatory power of the model concerning surface runoff generation and soil moisture dynamics. For instance, model results of infiltration experiments at the plot and hillslope/field scales show that it is possible to simulate high infiltration rates jointly with a relatively slow movement of moisture within the soil matrix, field phenomena often observed in the case of heavy rainfall. Other simulation efforts deal with the non-linear and space-time variable effects of soil surface conditions. This is a rather important feature for flood generation in the case of high rainfall intensity and low soil infiltrability.

How to cite: Bronstert, A., Niehoff, D., and Schiffler, G. R.: Modelling Infiltration and Infiltration Excess: The Importance of Fast and Local Processes, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-7622, https://doi.org/10.5194/egusphere-egu23-7622, 2023.

Climate change increases the risk of water scarcity due to a higher probability of droughts and heat waves, even in temperate countries. A currently controversial adaptation strategy deployed by farmers is the multiplication of small dams to intercept water during the winter months (either from hillslopes or headwater streams), and store it through the summer months to secure irrigation and cattle watering. However, the impact of such practices on catchment water balance and streamflow dynamics is difficult to assess, because of the lack of reliable data but also the lack of models able to represent these devices. In the framework of the J2000 distributed hydrological model, we developed a simple component representing farm dams in mesoscale to regional scale catchments. The model was applied to the Rhône catchment in France (~ 100000 km²), using a database of known locations of farm dams to assess the impact of these dams on catchment water balance components and several streamflow dynamics indicators. Several scenarios were simulated, under present climate, according to various parameterizations such as absence / presence of dams but also varying the density and dimensions of the reservoirs, as well as their infiltration properties and drainage areas. The results show that the impact of such dams is potentially high, but is also highly dependent on the parameterization scenarios, thus confirming the need for more complete land and water uses databases.

How to cite: Branger, F., Bonneau, J., Pouchoulin, S., and Sauquet, E.: Cumulative impact of farm dams on catchment water balance and streamflow dynamics at the regional scale. A numerical experiment using a distributed hydrological model., EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-8106, https://doi.org/10.5194/egusphere-egu23-8106, 2023.

EGU23-8529 | ECS | Posters virtual | HS2.2.1

Spatiotemporal analysis and modeling of nonstationarity in hydrological time series 

Nishant Kumar, D. Nagesh Kumar, and Tirthankar Roy

Detection of nonstationarity in hydrological time series is most commonly done through one or two unit root tests, which usually do not account for all the possible reasons that could induce nonstationarity in a time series. To overcome this, we carried out five different unit root tests, i.e., Augmented Dickey-Fuller (ADF) test, Kwiatkowski Phillips Schmidt Shin (KPSS) test, Phillips Perron (PP) test, Variance Ratio (V ratio) test, and Leybourne McCabe (LMC) test, along with the line spectrum analysis in the frequency domain. These tests were conducted on daily rainfall data at forty contiguous grid points around the Malaprabha basin in India using data from the Indian Meteorological Department. The main goal was to find different nonstationary time series and investigate the spatiotemporal patterns of the nonstationarity and use that information to further develop nonstationary time series models through three different modeling approaches, i.e., Seasonal Autoregressive Integrated Moving Average (SARIMA), Exponential Smoothing (ES), and Long Short-Term Memory (LSTM). The performance of these models was evaluated on the basis of Nash Sutcliffe Efficiency (NSE) and R2 value. 

How to cite: Kumar, N., Kumar, D. N., and Roy, T.: Spatiotemporal analysis and modeling of nonstationarity in hydrological time series, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-8529, https://doi.org/10.5194/egusphere-egu23-8529, 2023.

EGU23-9526 | ECS | Orals | HS2.2.1

Multi-basin calibration of the ECMWF land-surface model ECLand 

Stephan Thober, Robert Schweppe, Matthias Kelbling, Sebastian Müller, Juliane Mai, Christel Prudhomme, Gianpaolo Balsamo, and Luis Samaniego

Accurately and efficiently estimating parameters for spatially distributed environmental models is impossible without proper regularization of the parameter space. The Multiscale Parameter Regionalization (MPR, Samaniego et al. 2010) makes use of high-resolution physiographic data (i.e., physiographic data such as soil maps and land cover information) to translate local land surface properties into model parameters. MPR consists of two steps: first, the high-resolution model parameters are derived from physiographic data via transfer functions at the native resolution. Second, the model parameters are upscaled to the target resolution used by the environmental modelling application. MPR has been already successfully applied for the mesoscale hydrologic model (mHM, Samaniego et al. 2010, Kumar et al. 2013). The model agnostic, stand-alone version  implementation of MPR (Schweppe et al., 2022) allows applying this technique to any land-surface model or hydrological model.

In this study, we apply the MPR to optimize parameters for the land-surface model ECLand (Boussetta et al. 2021) of the ECMWF Integrated Forecasting System. Calibrating ECLand parameters at individual river basins leads to an improved representation of river discharge, i.e., an improved Kling-Gupta efficiency. In an ongoing effort, we explore model parameters optimization on multiple basins simultaneously to provide an improved representation of river discharge at a global scale. The calibration locations are chosen to cover different climates, soil, and land characteristics among other features.

References:

Samaniego L., Kumar, R., and Attinger, S.: “Multiscale parameter regionalization of a grid-based hydrologic model at the mesoscale”, Water Resour. Res., 46, 2010.

Kumar, R., Samaniego, L., and Attinger, S.: “Implications of distributed hydrologic model parameterization on water fluxes at multiple scales and locations”, Water Resources Res, 2013

Schweppe, R., Thober, S., Müller, S., Kelbling, M., Kumar, R., Attinger, S., and Samaniego, L.: MPR 1.0: a stand-alone multiscale parameter regionalization tool for improved parameter estimation of land surface models, Geosci. Model Dev., 15, 859–882, https://doi.org/10.5194/gmd-15-859-2022, 2022

Boussetta S, Balsamo G, Arduini G, Dutra E, McNorton J, Choulga M, Agustí-Panareda A, Beljaars A, Wedi N, Munõz-Sabater J, de Rosnay P, Sandu I, Hadade I, Carver G, Mazzetti C, Prudhomme C, Yamazaki D, Zsoter E. ECLand: The ECMWF Land Surface Modelling System. Atmosphere. 2021; 12(6):723. https://doi.org/10.3390/atmos12060723

How to cite: Thober, S., Schweppe, R., Kelbling, M., Müller, S., Mai, J., Prudhomme, C., Balsamo, G., and Samaniego, L.: Multi-basin calibration of the ECMWF land-surface model ECLand, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-9526, https://doi.org/10.5194/egusphere-egu23-9526, 2023.

EGU23-9706 | ECS | Orals | HS2.2.1

Hydrological Signature Representation of 7533 KGE Calibrated Conceptual Model Structures 

Diana Spieler and Niels Schütze

Discussions calling for more rigorous evaluation practices for hydrologic models have recently increased. In addition to the widely used integral objective functions, hydrologic signatures are becoming common evaluation metrics for proving the suitability of hydrologic models for specific application purposes.

This work calibrates 7488 fixed conceptual model structures using KGE as an objective function. These structures range from a 1 to 3 storage model space previously used for an automatic model structure identification experiment. In this experiment we simultaneously calibrated the model structure (number of stores and flux equations) and its parameter values. Additionally, we calibrated 45 literature-based model structures (MARRMoT Toolbox) to extend the structural diversity in the analyzed models. We select well-performing models based on their KGE value (as is common practice) and analyze their performance using 12 selected hydrological runoff signatures. These signatures represent five aspects of the hydrological regime (magnitude, frequency, duration, rate of change, and timing). The large number of model structures, calibrated to the streamflow of 12 MOPEX catchments, allows general insight into how well common conceptual model structures can represent observed hydrological behavior evaluated by signatures.

Results show a general behavior of model structures calibrated to KGE to perform well in representing runoff ratio, mean discharge, the 95th streamflow percentile, and the mean half-flow date. However, the analyzed conceptual model structures struggle to represent low flow and frequency signatures. When evaluated only for KGE, we can identify dominating model structures over all catchments. When evaluated for signatures, there are no model preferences over all analyzed catchments but different models seem to have their merits under specific conditions. These results support the need for ensuring model adequacy for a given task.

How to cite: Spieler, D. and Schütze, N.: Hydrological Signature Representation of 7533 KGE Calibrated Conceptual Model Structures, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-9706, https://doi.org/10.5194/egusphere-egu23-9706, 2023.

EGU23-9829 | Orals | HS2.2.1

Evaluating global hydrological-process modelling beyond river discharge observations 

Rafael Pimentel, Louise Crochemore, Jafet C.M. Andersson, and Berit Arheimer

Catchment modelling of water balance components is nowadays done at high spatial resolution for continental and global scales, thanks to the increasing computational capacity and the growing trend towards open data. One of these process-based models is the World-Wide HYPE (WW-HYPE; Arheimer et al., 2020), which was set-up by a stepwise calibration strategy to avoid equifinality when using streamflow data for parameter estimation. In this presentation we suggest to further evaluate whether the model is right for the right reason by comparing internal variables against independent Earth Observations (EO). We then assume that the results are robust if the two different sources of data reveal the same results. This approach could become a new standard method today for evaluating continuous process-based global models as there are numerous EO products representing various hydrological variables, most of them covering at least the last decade.

We propose to compare three aspects when evaluating robustness in global hydrological variables: i) long-term means, ii) seasonal variability through monthly means, and iii) equifinality by comparing model-streamflow performance versus internal variable performance.

We applied this method by comparing six hydrological variables (potential and actual evapotranspiration, snow cover, snow water equivalent, soil moisture or changes in water storages) from EO-products (based on MODIS, GlobSnow, ESA-CCI Soil Moisture and GRACE) with WWH variables for the time-period 2000-2014 (Pimentel et al, 2023). We then found that the general patterns in the hydrological cycle show good agreement between catchment modelling and EO at the global scale, although some months in water-storage changes differed. These dissimilarities indicate that hydrological variables above the ground and earlier in the flow path are more robust than the sub-surface downstream processes, such as soil moisture distribution and water-storage changes, which reflect more complex processes that can be challenging to describe both by hydrological models and satellite sensors. Regarding geographical distribution, there is a larger spread in results from regions with extreme characteristics, such as cold regions (Canadian prairies), arid regions (western USA, deserts), highly forested areas (Amazonas), and transition zones (Sahel and Mediterranean Basin). This indicate that the particularity of these regions calls for specific regional modelling and monitoring approaches rather than continental or global approaches.

On the contrary, in temperate regions at mid-latitudes, e.g., eastern USA and central Europe, almost all the hydrological variables were found robust. With respect to equifinality, overall, there were no indication on good discharge performance and bad internal model representation. The exercise shows the potential in using EO products for model evaluation beyond traditional river-discharge observations from gauges, to first assess the robustness of hydrological variables and second to determine which processes should be better represented in model parameterisation, without forgetting that EO products are not a ground truth and are also assigned with uncertainties.

 

References:

Arheimer et al., 2020: Global catchment modelling using World-Wide HYPE (WWH), open data and stepwise parameter estimation, HESS 24, 535–559, https://doi.org/10.5194/hess-24-535-2020

Pimentel et al., 2023: Assessing Robustness in Global Hydrological Modelling through EO Comparisons, HSJ (in review)

How to cite: Pimentel, R., Crochemore, L., Andersson, J. C. M., and Arheimer, B.: Evaluating global hydrological-process modelling beyond river discharge observations, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-9829, https://doi.org/10.5194/egusphere-egu23-9829, 2023.

EGU23-9847 | Orals | HS2.2.1 | Highlight

Impact of calibration metric selection and spatial heterogeneity in soil parameters on the realism of distributed hydrological models 

Pablo A. Mendoza, Nicolás Vásquez, Nicolás Cortés-Salazar, Naoki Mizukami, and Ximena Vargas

Distributed hydrological models are useful tools to explicitly simulate the spatial heterogeneity of water and energy fluxes and storages. Nevertheless, their parameters are typically calibrated using streamflow-based objective functions that integrate information on the spatial variability of physical processes into a single metric. Additionally, these models contain several soil parameters that can be distributed in space, affecting the spatial representation of hydrological variables. Here, we examine the implications of streamflow-based calibration metric selection and spatial heterogeneity in soil parameters on the realism of model simulations, with emphasis on spatial patterns. To this end, we conduct several calibration experiments in six pilot basins with different hydrological regimes (two snowmelt-driven, two mixed-regime, and two rainfall-driven basins), in central-southern Chile, using the Variable Infiltration Capacity (VIC) model coupled with the mizuRoute routing model. In each experiment we assess, for a given calibration objective function, the effects of distributing individual soil parameters using a spatial regularization strategy based on principal component analysis of physiographic and soil characteristics (elevation, slope, clay content, sand content and bulk density), defining the case of spatially constant soil parameters as the benchmark (i.e, only meteorological forcing data and vegetation attributes are spatially distributed). To evaluate simulated spatial patterns, we use satellite remote sensing data of soil moisture from the ESA-CCI product, and fractional snow-covered area, actual evapotranspiration (ET), and land surface temperature from MODIS products. The results show that similar streamflow performance metrics can be achieved with different combinations of regularized soil parameter and calibration metric; however, the simulated spatial patterns can be considerably different, without clear connections with the hydrological regime. Further, a streamflow-based calibration is insufficient to represent the seasonality of other variables, especially in water-limited catchments, where important shifts (e.g., up to five months) in peak ET can be obtained compared to the reference product.

How to cite: Mendoza, P. A., Vásquez, N., Cortés-Salazar, N., Mizukami, N., and Vargas, X.: Impact of calibration metric selection and spatial heterogeneity in soil parameters on the realism of distributed hydrological models, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-9847, https://doi.org/10.5194/egusphere-egu23-9847, 2023.

Evapotranspiration (ET) and recharge fluxes are fluxes at the land-atmosphere interface. Evaporative flux links the surface and atmospheric systems and the recharge flux links the surface and subsurface systems. These are two critical fluxes in the water cycle that have major impact on agriculture, water supply, climate, biogeochemical cycles and etc. These fluxes are interconnected and depend on the soil moisture content.  In situ measurements of ET and recharge are costly, limited and cannot be readily scaled to regional scales relevant to weather and climate studies. Sequence of land surface state observations of moisture (SM) and temperature (LST), widely available from remote sensing across a range of scales, contain implicit information that can be used for characterization and mapping of evapotranspiration and recharge fluxes.

In this work, A variational data assimilation (VDA) framework is developed to estimate key parameters of ET and recharge flux by assimilating Soil Moisture Active Passive (SMAP) soil moisture and Geostationary Operational Environmental Satellite (GOES) land surface temperature data into a coupled dual-source energy and water balance model. These parameters include neutral bulk heat transfer coefficient (CHN) and evaporative fraction from soil (EFS) and canopy (EFC)) that regulate the partitioning of available energy, and the effective saturated hydraulic conductivity (Ks) and bore size index (B) that regulate the movement of moisture into the soil column. The uncertainties of the retrieved parameters are estimated through the inverse of the hessian of the cost function, obtained using the lagrangian methodology. Analysis of the second-order information provides a tool to identify the optimum parameter estimates and guides towards a well-posed estimation problem.

The proposed framework is implemented over the US Southern great plain (SGP) and Oklahoma Panhandle region (with computational grid size of 0.05 degree) to map evapotranspiration and recharge fluxes across a range of temporal scales. Comparison with in-situ observations from the USCRN and the Mesonet sites show that the proposed assimilation framework can accurately estimate the temporal variability of root zone soil moisture profile. The evapotranspiration estimates show good agreement with the in-situ data from Atmospheric Radiation Measurement (ARM) sites at different locations and the estimated annual recharge flux values are within the range suggested in the literature for this region. Results demonstrate the success of the proposed assimilation framework in estimating key water cycle components and their interrelations across a range of spatial and temporal scales from remotely sensed near surface soil moisture and temperature data.

How to cite: Farhadi, L. and Mahmood, A.: An Integrated Variational Framework for Coupled Estimation of Evapotranspiration and Recharge by Assimilating Land Surface Soil Moisture and Soil Temperature Data , EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-9997, https://doi.org/10.5194/egusphere-egu23-9997, 2023.

EGU23-10121 | ECS | Posters on site | HS2.2.1

Evaluation of four hydrological models to simulate daily streamflow time series in a tropical river basin of Brazil 

Leandro Ávila, Reinaldo Silveira, André Campos, Nathalli Rogiski, Camila Freitas, Cássia Aver, and Fernando Fan

The Electric Energy Company of Parana (COPEL GeT), the Meteorological System of Parana (SIMEPAR) and RHAMA Consulting company are undertaking the research project PD-6491- 0503/2018 for the development of a hydrometeorological seasonal forecasting for Brazilian reservoirs. The project, sponsored by the Brazilian Electricity Regulatory Agency (ANEEL) under its research and development program, aims the forecasting of streamflow, at temporal scales ranging from 1 to 270 days, at hydro power enterprises, which are integrated by the National Power System Operator (ONS) through its Interconnected System (SIN). With the aim of implement a seasonal forecasting system using different hydrological modeling approaches, it is necessary first to validate the use of different hydrological models during the calibration and validation stages. This work evaluates the performance of four conceptual hydrological models to represent daily streamflow regimes at four hydropower plants located in the Teles Pires river basin (Brazil). The adopted models included the GR4J, HYMOD, HBV, and the SMAP. The calibration of the parameters for each hydrological model was performed using the SCE-UA method and a triangular weighting function was adopted for routing the hydrograph between sub-watersheds. The evaluation of each model was elaborated by the comparison of the observed and simulated streamflow time series during the calibration (2010-2016) and the validation period (2016-2019) using deterministic metrics and statistical tests. A post-processing procedure based on the quantile-quantile method was applied in order to correct the simulated data and reduce the bias with respect the observed data. In general, the results show that the SMAP model present a better performance to simulate the daily streamflow regimes at the simulated hydropower plants, with Nash-Sutcliffe coefficient (NSE) greater than 0.65, and NSElog values greater than 0.8. In addition, the bias correct procedure shows a significant improvement in the adjust of the simulated data to represent the periodic streamflow regimes in the selected river basin.

How to cite: Ávila, L., Silveira, R., Campos, A., Rogiski, N., Freitas, C., Aver, C., and Fan, F.: Evaluation of four hydrological models to simulate daily streamflow time series in a tropical river basin of Brazil, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-10121, https://doi.org/10.5194/egusphere-egu23-10121, 2023.

Physically-based hydrologic models can accurately simulate streamflow in natural environment, but they cannot precisely consider the anthropogenic disturbance caused by the operation of large-scale dams. We tried to overcome this issue by developing a hybrid modeling framework, consisting of physically-based models for simulating upstream natural watersheds and deep-learning-based models for simulating dam operation. The model was developed for the Paldang Dam watershed, a major water source for Seoul metropolitan area, where the importance of stable water supply has increased due to the increase of population and water use per capita. The prediction performance of the hybrid model was compared with that of models built based only on the physically-based hydrologic model, namely the Variable Infiltration Capacity model, with single and cascaded structure. For the validation period, Nash-Sutcliffe Efficiency from the developed hybrid model, the single model, and the cascaded model were 0.6410, -0.1054, and 0.2564, respectively, suggesting that the consideration of dam operation aided by the machine learning algorithm is essential for accurate assessment of streamflow.

This work was supported by the National Research Foundation of Korea(NRF) grant funded by the Korea government(MSIT) (No. NRF-2022R1A4A3032838).

How to cite: Kim, Y. and Kim, D.: A Hybrid Hydrological Modelling Approach Combining Physically-Based and Deep-Learning-Based Models to Consider Dam Operations, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-10287, https://doi.org/10.5194/egusphere-egu23-10287, 2023.

EGU23-10593 | ECS | Orals | HS2.2.1

Incorporating The Variable Contributing Area Concept in The HYPE Modelling Framework 

Mohamed Ismaiel Ahmed, Kevin Shook, Alain Pietroniro, Tricia Stadnyk, John W. Pomeroy, Charlotta Pers, and David Gustafsson

Modelling the hydrology of the North American prairie region is complicated by the dominance of cold region processes and by the flat topography, which contains millions of depressions. The depressions contribute to variable contributing areas in prairie basins, due to their varying water storage. The relationships between the depressional storage, and the contributing fraction are hysteretic and strongly influence the basin responses. Most hydrological models do not represent these complex hysteretic relationships, and therefore struggle in simulating the hydrology of the region. In this study, we propose a novel Hysteretic Depressional Storage (HDS) algorithm that is based on the known hysteretic properties of prairie depressions. HDS is implemented into the HYPE modelling framework to improve the simulations of prairie streamflow by accounting for the variable contributing area. The modified HYPE, and the original program are tested on two depression-dominated basins in Saskatchewan, Canada. The modified HYPE model show improved simulation of streamflows compared to the original HYPE model. The HDS algorithm can contribute to improving the streamflow simulation of not only the North American prairie region, but also in the arctic and Siberian regions, which are dominated by the same complex depressional storages. The modified HYPE model should also improve the estimates of surface water storage and the resulting evaporative fluxes in these regions, increasing model fidelity and improving water budget estimates in these complex terrains, especially under changing climates.

How to cite: Ahmed, M. I., Shook, K., Pietroniro, A., Stadnyk, T., Pomeroy, J. W., Pers, C., and Gustafsson, D.: Incorporating The Variable Contributing Area Concept in The HYPE Modelling Framework, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-10593, https://doi.org/10.5194/egusphere-egu23-10593, 2023.

The Geum River basin, located in the west-central part of the Korean Peninsula, is the third largest and minimally human-disturbed river basin in South Korea. Streamflow and available water resources from this basin is critical for water supply for agriculture. Due to the increased population, industrialization, and climate change, changes in streamflow and available water resources for the Geum River are expected. However, there are limitations in analyzing water resource changes in the Geum River Basin with discontinuous and relatively short observational streamflow records.

In this study, we propose to dynamically downscale daily surface and base runoff data from the 10-km ERA5 reanalysis product via VIC-River Routing model. The VIC-River Routing model was ran at the 90-meter spatial resolution with geographical information to reconstruct long-term naturalized streamflow data over 1950-2021. In the VIC-River Routing model, the flow direction, stream order, and slope estimated from the 90-meter digital elevation model (DEM) over Geum River basin as the topographical parameters. This downscaled natural streamflow data will provide an opportunity to investigate hydroclimatic changes of the hydrologic regime of Geum River.

How to cite: Kim, B.-H. and Kam, J.: Dynamical downscaling of ERA5-based high-resolution streamflow dataset over the Geum River basin, South Korea via VIC-river routing model (1950-2021), EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-10748, https://doi.org/10.5194/egusphere-egu23-10748, 2023.

EGU23-10786 | Posters on site | HS2.2.1

Estimation of spatio-temporal groundwater recharge in Jeju Island, Korea 

Jeong Eun Lee, Chul-Gyum Kim, Jeongwoo Lee, Il-Moon Chung, and Sun Woo Chang

Accurate estimation of groundwater recharge in Jeju Island, which relies on groundwater for most of its water use, is very important for water resource management and planning. However, Jeju watershed is a volcanic island with high permeability, ephemeral streams and mountain areas, so it is difficult to estimate the hydrological components using existing hydrological models. To overcome these limitations, SWAT-K (Soil and Water Assessment Tool-Korea), which can simulate ephemeral stream and threshold runoff, was used to estimate hydrological components (such as precipitation, evapotranspiration, runoff, and groundwater recharge) of Jeju watershed (~1,828 km2). The overall procedure of SWAT-K modeling (model setup, calibration and validation) was performed from 1991 to 2020. The simulated and observed daily streamflows were compared and showed a good agreement. In particular, a reasonable estimation of groundwater recharge was confirmed through the comparison of simulated groundwater recharge and the observed groundwater level. Finally, the spatio-temporal groudwater recharge characteristics were analyzed using the SWAT-K results.

Acknowledgement : Research for this paper was carried out under the KICT Research Program (project no.20220275-001, Development of coastal groundwater management solution) funded by the Ministry of Science and ICT.

How to cite: Lee, J. E., Kim, C.-G., Lee, J., Chung, I.-M., and Chang, S. W.: Estimation of spatio-temporal groundwater recharge in Jeju Island, Korea, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-10786, https://doi.org/10.5194/egusphere-egu23-10786, 2023.

EGU23-10854 | Orals | HS2.2.1

Intercomparison of local evapotranspiration estimates at high latitudes 

Kolbjørn Engeland, Helene Birkelund Erlandsen, Emiliano Gelati, Shaochun Huang, Devaraju Narayanappa, Norbert Pirk, Olga Silantyeva, Lena Merete Tallaksen, Astrid Vatne, and Yeliz A Yilmaz

The main motivation for this study is to improve knowledge about the actual evapotranspiration in cold environments. Erlandsen et al (2021) summarize evapotranspiration estimates that range from 175 – 500 mm/year, i.e. between 13 and 31% of mean annual precipitation for Norway. The study is part of the LATICE (Land-ATmosphere Interactions in Cold Environments) strategic research initiative at the University of Oslo. Here we have launched a new initiative, LATICE MIP-ET that aims to compare model estimates of evapotranspiration (ET) in a high latitude environment.

In this study, we compare local observations of evapotranspiration with local estimates from two land surface models (CLM and SURFEX) and three hydrological models (SHYFT, HBV and Lisflood). Observations are available at five eddy covariance flux sites with a gradient in climate across Norway, from low altitude forested and grassland sites to high mountain and high latitude sites. To run the models three sets of forcing data will be used.

The presentation will summarize the models’ ability to capture diurnal and seasonal variations in evapotranspiration as compared to the observations. We will also compare how models simulate the relationship between potential and actual evapotranspiration and assess the models’ sensitivity to the choice of vegetation-and soil parameters and forcing data used.

References:

Erlandsen, H.B., Beldring, S., Eisner, S., Hisdal, H., Huang, S., Tallaksen, L.M. (2021) Constraining the HBV model for robust water balance assessments in a cold climate. Hydrology Research 2021; nh2021132. doi: https://doi.org/10.2166/nh.2021.132

How to cite: Engeland, K., Erlandsen, H. B., Gelati, E., Huang, S., Narayanappa, D., Pirk, N., Silantyeva, O., Tallaksen, L. M., Vatne, A., and Yilmaz, Y. A.: Intercomparison of local evapotranspiration estimates at high latitudes, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-10854, https://doi.org/10.5194/egusphere-egu23-10854, 2023.

Space-time patterns of surface fluxes and states have direct implications for boundary layer growth, cloud development, phenology, and runoff generation, among other processes. Emerging field-scale resolving land surface models (the terrestrial component of Earth system models), such as HydroBlocks, aim to represent this complexity by modeling the water, energy, and biogeochemical cycles at meter-km spatial scales over continental extents. Although there have been significant advances in the representation of heterogeneity in land surface modeling over the past decade, there has yet to be a concerted effort to evaluate the realism of the simulated time-evolving field-scale spatial patterns; this, in part, is due to the challenge of how to interpret the space-time fields. Empirical space-time covariance presents a unique solution; it can robustly summarize the space-time structure of a given flux or state for a given area (e.g., watershed) via a simple 2D surface (e.g., Figure 1). In this presentation, we will demonstrate how space-time covariance provides an effective and efficient approach to facilitate evaluation of the simulated spatiotemporal patterns.

            As a proof of concept, the simulated spatiotemporal patterns of land surface temperature (LST) of a HydroBlocks model simulation over the central United States are evaluated using observations from satellite remote sensing (GOES-16/17). First, for each 0.25 arcdegree grid cell over the study domain, the empirical spatiotemporal covariance functions (ESTCFs) are assembled for HydroBlocks (simulation) on one side and GOES (observation) on another. For this case, each ESTCF is calculated from hourly data for clear-sky pixels during the summers of 2017-2022. The ESTCFs are then initially compared via simple metrics (e.g., RMSE). To ease understanding, a space-time parametric covariance function is then fit to each ESTCF; the comparison of the parameters (e.g., spatial correlation length) provides a richer understanding of the strengths and weaknesses of the model. The resulting analysis illustrates how space-time covariance can efficiently summarize the complex simulated spatiotemporal patterns and thus serve as a useful metric to both evaluate and inform model development to improve process representation.

How to cite: Chaney, N. and Torres-Rojas, L.: Space-time covariance: An effective tool to evaluate the simulated spatiotemporal patterns in land surface models, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-11061, https://doi.org/10.5194/egusphere-egu23-11061, 2023.

EGU23-12205 | ECS | Posters on site | HS2.2.1

Hydrological simulation of flow rates in (un)gauged catchments of East-Flanders (Belgium) by the SWAT+ and PDM models. 

Kobe Braet, Lara Van Der Veken, Emma Tronquo, Jonas-Frederik Jans, and Niko Verhoest

Hydrological models are key instruments to predict hydrological extremes, such as droughts and floods. These hydrological extremes are becoming more and more frequent in Belgium. Therefore, creating a climate robust water system is becoming a priority. This research aims to provide flow rate predictions for several catchments in the province of East-Flanders based on meteorological, soil, land use and DEM data. These were collected by local monitoring networks and transformed by, among others, local pedotransfer functions and spatial interpolation methods.

A physically based model (SWAT+) is used to simulate flow rate estimates for (un)gauged catchments and to calculate different scenarios related to land use change or a changing climate. The simulated flow rates are used as training data for a simple conceptual model (PDM). The PDM-model is more suited for real-time modelling and can be used as a basis to take policy decisions. The strength of physically based models is that they require minor calibration, while conceptual models have a more feasible computation time. By combining the strengths of both models, an estimate can be made for the flow rates in different (un)gauged catchments of East-Flanders.

How to cite: Braet, K., Van Der Veken, L., Tronquo, E., Jans, J.-F., and Verhoest, N.: Hydrological simulation of flow rates in (un)gauged catchments of East-Flanders (Belgium) by the SWAT+ and PDM models., EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-12205, https://doi.org/10.5194/egusphere-egu23-12205, 2023.

EGU23-12558 | ECS | Orals | HS2.2.1

Multi-model approach in a variable spatial framework for streamflow simulation 

Cyril Thébault, Charles Perrin, Vazken Andréassian, Guillaume Thirel, Sébastien Legrand, and Olivier Delaigue

Accounting for the variability of processes and climate conditions between catchments and within catchments remains a challenge in hydrological modelling. To address this issue, various approaches were developed over the past decades. Among them, multi-model approaches provide a way to quantify and reduce the uncertainty linked to the choice of model structure, and semi-distributed approaches propose a good compromise to account for spatial variability of the processes by dividing the catchment in sub-catchments while maintaining a limited level of complexity. However, these two approaches were barely applied together. The aim of this work is to answer the following question: what are the contributions of multi-model approaches in a variable spatial framework for the simulation of streamflow over a large sample of catchments?

To this end, a large set of 121 uninfluenced catchments in France was assembled, with precipitation, evapotranspiration and streamflow data at an hourly time step over the 1998-2018 period. The semi-distribution set-up was kept simple by considering a single intermediate catchment between a downstream station and one or more upstream catchments. The multi-model approach was implemented with 13 hydrological structures, three calibration options and two spatial frameworks, for a total of 78 distinct modelling options. A simple average method was used to combine the streamflow at the outlet of the catchments and sub-catchments. In this work, the benchmark considered is the most efficient lumped model considered individually on each catchment.

The semi-distributed multi-model approach generates better performance at the time-series scale than the lumped models. The gain is mainly brought by the multi-model aspect while the spatial framework gives a more occasional benefit. This study also highlight the advantages of using a large set of models in a semi-distributed multi-model framework to simulate streamflow in a large sample hydrology context.

How to cite: Thébault, C., Perrin, C., Andréassian, V., Thirel, G., Legrand, S., and Delaigue, O.: Multi-model approach in a variable spatial framework for streamflow simulation, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-12558, https://doi.org/10.5194/egusphere-egu23-12558, 2023.

EGU23-13397 | ECS | Orals | HS2.2.1

How could we improve the spatial consistency of water fluxes in a semi-distributed hydrological model? A multi-criteria approach 

Shu-Chen Hsu, Alban de Lavenne, Charles Perrin, and Vazken Andréassian

While hydrological models aim to represent the hydrological behaviour of catchments, many of them have been streamlined on the exclusive basis of streamflow simulation performance, i.e. among the possible parameter sets, the 'optimal' is the one which brings the best simulation of streamflow during the calibration period. However, we sometimes encounter 'optimal' sets which perform well in discharge simulation but yield unrealistic simulations of other fluxes (e.g. actual evaporation fluxes, inter-catchment groundwater fluxes). Previous studies tried to constrain the exploration of parameter space with measurements complementary to river discharge: this application of extra information aims to increase the physical realism of the model compared to discharge-only calibration. In this study, we carry out an original investigation to take advantage of the spatial patterns of the complementary data in order to drive the calibration towards a more spatially consistent solution.

We propose here a feasibility test, to constrain the spatial consistency of fluxes of a semi-distributed GR model (GRSD). Our study area is the Somme catchment (6100 km2 ) with 17 internal gauging stations, each of them having more than 15 years of discharge measurement. As a first step, we use the long-term actual evaporation from Budyko-estimation as an extra constraint, which has been widely used for describing spatial patterns of climate. In the second step, we develop a criterion describing the spatial consistency between the pattern of measured and simulated fluxes. By constraining the model with extra information, the model is expected to yield a more consistent simulation of fluxes in comparison with the classical calibration practice. Moreover, we analysed the impact of this additional constraint on the spatial organisation of IGF over the catchment as both the other components in water balance analysis, actual evaporation and discharge, are constrained.

How to cite: Hsu, S.-C., de Lavenne, A., Perrin, C., and Andréassian, V.: How could we improve the spatial consistency of water fluxes in a semi-distributed hydrological model? A multi-criteria approach, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-13397, https://doi.org/10.5194/egusphere-egu23-13397, 2023.

EGU23-13592 | ECS | Posters on site | HS2.2.1

Improved ecohydrologic modelling using spatial patterns of remotely sensed land surface temperature 

Doris Duethmann, Martha Anderson, Marco Maneta, and Doerthe Tetzlaff

Considering different types of hydrologic observations for model calibration in addition to streamflow is a suitable strategy to better constrain model parameters and improve process-consistency of hydrologic models. In this regard, land surface temperature (Ts) is an interesting variable as it is at the core of the surface energy and water balance. This study aims at evaluating the benefits of integrating spatial patterns of satellite-derived Ts into calibration of the process-based ecohydrologic model EcH2O. We furthermore explore the value of an increasing number of Ts images in the calibration period. The study is performed in a mixed land cover catchment in NE Germany and makes use of Landsat-derived Ts data. Our results show that satellite-derived Ts is useful for reducing uncertainties of energy-balance related vegetation parameters, which are hardly constrained when the model is calibrated to streamflow only. Good model performance with respect to streamflow does not preclude low performance in terms of Ts and including satellite-derived Ts for model calibration clearly improves simulated spatial patterns of Ts. Spatial patterns in observed Ts are shown to be strongly related to land cover class and a vegetation index, and our results indicate that further model improvements may be possible by better representing observed variations of leaf area index within the ecohydrologic model.

How to cite: Duethmann, D., Anderson, M., Maneta, M., and Tetzlaff, D.: Improved ecohydrologic modelling using spatial patterns of remotely sensed land surface temperature, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-13592, https://doi.org/10.5194/egusphere-egu23-13592, 2023.

EGU23-13624 | ECS | Posters on site | HS2.2.1

Enhancing Predictions of Land Subsidence Induced by the Groundwater Withdrawal in the Mekong Delta, Vietnam 

Artur Guzy, Philip Minderhoud, Bente Lexmond, Claudia Zoccarato, and Pietro Teatini

Globally, land subsidence caused by groundwater pumping is a common phenomenon. Numerous subsurface processes, both natural and anthropogenic, contribute to its occurrence. In coastal regions, severe land subsidence exacerbated by groundwater pumping is particularly detrimental. On top of that, coastal areas affected by natural compaction, river delta consolidation processes, and additional exposure to drainage-induced aquifer-system compaction are especially susceptible to flooding and salinization due to the steadily rising sea level triggered by climate change.

The Mekong delta, one of the world's largest deltas, is densely populated and crucial for agricultural production. The delta is low-lying and has a high rate of natural compaction, whereas human activities accelerate land subsidence. A numerical model of groundwater-extraction-induced aquifer-system compaction was developed in 2017 to demonstrate the effects of 25 years of groundwater extraction on land subsidence in the delta. The model encompassed the time range from 1991 to 2016 using geological, hydrogeological, geomechanical, and remote sensing data. In 2020, the model was updated to include a surface water network. Six scenarios were developed to simulate potential future pathways of hydraulic head evolution and aquifer-system compaction in the Mekong delta from 2019 to 2100.

Our research aims to enhance the reliability of the existing numerical model of groundwater extraction-induced aquifer-system compaction in the Mekong delta, given the significance of such scenarios in the development of policies to mitigate the negative effects of groundwater pumping.  Our research focuses on four steps.

First, a novel subsurface model representation.

The 3D subsurface model of the Mekong delta was developed using ten hydrogeological cross-sections derived from 96 geological borehole logs interpolated linearly. This resulted in a subsurface model consisting of 15 layers, including seven aquifers, seven aquitards, and a phreatic top layer. The goal of the current study is to develop a new schematisation of the aquifer system within the Mekong delta based on 522 borehole logs and to investigate the spatial variability of the aquifer system using advanced geostatistical tools.

Second, a hydrogeological schematization enhancement.

In the current schematisation, aquitards are discretized as a single layer, resulting in the inability to simulate delayed groundwater pressure propagation within the aquitard. Several additional models with refined aquitard discretization are constructed and compared to evaluate the effect.

Third, the quantification of the influence of deterministic modelling on compaction.

The hydrogeological model is deterministically parameterized and calibrated using hydraulic head time series. Utilizing stochastic modelling of hydrogeological parameters, the impact of this deterministic modelling approach on simulated compaction is determined.

Fourth, a hydrogeological and geomechanical parameters consistency improvement.

The previous hydrogeological and geomechanical model parameterizations are inconsistent since the groundwater model and the geomechanical module were initially parameterized and calibrated independently. To address this issue, an iterative procedure is used to calibrate storage and compression indexes consistently for each individual model layer. This is accomplished by utilising groundwater head datasets recorded by 358 piezometers and land subsidence datasets retrieved by InSAR from 2006 to 2010 and 2016 to 2019.

How to cite: Guzy, A., Minderhoud, P., Lexmond, B., Zoccarato, C., and Teatini, P.: Enhancing Predictions of Land Subsidence Induced by the Groundwater Withdrawal in the Mekong Delta, Vietnam, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-13624, https://doi.org/10.5194/egusphere-egu23-13624, 2023.

EGU23-13738 | ECS | Posters on site | HS2.2.1

A universal decay function based meteorologically-driven and calibration-free runoff generation module 

Prashant Istalkar and Basudev Biswal

An accurate estimate of streamflow has been a challenging task due to the complex and interconnected hydrological processes. A simple, robust and calibration-free runoff generation module is desirable in several water resource management applications. But spatial heterogeneity of, but not limited to, topography, soil and land cover makes it challenging to develop desirable runoff generation module. To address this, several runoff generations theories that apply laws of physics at the grid-scale were proposed and tested.  However, these theories have not shown a significant difference in performance on considering catchment as spatially distributed and a single unit(lumped). A typical runoff generation module follows saturation excess or infiltration excess mechanism for runoff generation. The root zone storage capacity (Smax), which controls the dynamics of water storage and partitioning of available water into different fluxes, is an important free-parameter in the saturation excess mechanism. The value of Smax needs to be estimated using observed streamflow time series. However, recent studies demonstrate that the Smax is controlled by local climate and land cover. So, in the current study, we hypothesized that runoff generation is solely governed by climate input and the amount can be estimated without explicit consideration of Smax. We tested the hypothesis using Dynamic Budyko (DB) framework, which simulates the runoff at a daily time scale using ‘instantaneous dryness index (Φ)’. We proposed a universal decay function to predict Φ using rainfall and potential evapotranspiration. The performance of proposed runoff generation module is compared with HBV and GR4J runoff generation modules for 416 MOPEX study basins. The proposed calibration free runoff generation module shows very similar performance to that of calibrated HBV and GR4J with median NSE as 0.68,0.7 and 0.68, respectively. The proposed framework can be coupled with any routing module to estimate the streamflow at basin outlet. The introduction of proposed framework address several long-term challenges in rainfall-runoff modeling. Our results suggest that more efforts should be considered in developing rainfall-runoff modeling frameworks that exploit information available in meteorological input to address streamflow dynamics.

How to cite: Istalkar, P. and Biswal, B.: A universal decay function based meteorologically-driven and calibration-free runoff generation module, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-13738, https://doi.org/10.5194/egusphere-egu23-13738, 2023.

EGU23-14099 | ECS | Orals | HS2.2.1

Validation of an irrigation scheme inside ORCHIDEE land surface model at global scale 

Pedro Felipe Arboleda Obando, Agnès Ducharne, Luiza Vargas-Heinz, Zun Yin, and Philippe Ciais

Irrigation activities play a key role in food production and consume 90% of freshwater withdrawal worldwide. These activities have a strong impact on water and energy budgets and associated biogeochemical cycles, and can have effects on local and regional climate. Furthermore, irrigation activities are projected to increase due to population growth and climate change. This context has encouraged the inclusion of irrigation in land surface models (LSMs), which simulate the continental branch in earth system models.

Here we present an irrigation scheme within the ORCHIDEE LSM that replicates flood and drip techniques. Water demand is calculated as the soil moisture deficit with respect to a target value. This deficit is estimated in the root zone of the crop and grass fraction (which contains both irrigated and rainfed crops), but the demand is limited by the fraction equipped for irrigation and by the water supply, i.e. water available in rivers and aquifers reduced to preserve a minimum volume in each water store for ecosystems. In addition, the scheme prioritizes water abstraction by source (surface or groundwater) according to the Siebert et al. map (2010). Hence, in a gridcell with little groundwater pumping infrastructure, most of the water will be extracted from the river, even if the water demand is not fully supplied. The water finally withdrawn for irrigation is allocated on the surface of the soil column for infiltration, and a maximum irrigation rate is set to prevent runoff production. The user-defined parameters that drive the scheme's response are the root zone depth and soil moisture target, the minimum volume left for ecosystems, and the maximum irrigation rate.

For validation, we use this scheme inside ORCHIDEE to run global offline simulations without and with irrigation. We use a set of parameter values that tries to fit the irrigation rates reported by AQUASTAT, while reducing the bias of evapotranspiration in irrigated areas with respect to the satellite-based products. We explore the possible reduction of bias in other variables like leaf area index, water storage anomalies and observed discharge. Finally, we correlate the bias reduction with landscape features to gain insights on the shortcomings of the irrigation scheme and ORCHIDEE.

How to cite: Arboleda Obando, P. F., Ducharne, A., Vargas-Heinz, L., Yin, Z., and Ciais, P.: Validation of an irrigation scheme inside ORCHIDEE land surface model at global scale, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-14099, https://doi.org/10.5194/egusphere-egu23-14099, 2023.

EGU23-14263 | ECS | Posters on site | HS2.2.1

Comparing river routing concepts in distributed hydrological modeling 

Laurène Bouaziz, Joost Buitink, Willem van Verseveld, Dirk Eilander, Mark Hegnauer, Eric Sprokkereef, Jasper Stam, Niek van der Sleen, and Rita Lammersen

Distributed hydrological models are valuable tools for operational and strategic water management planning. These models include a representation of vertical processes such as interception, transpiration and infiltration and require a lateral component to route the water downstream along the river network. The kinematic wave is a commonly used approach for lateral flow in distributed hydrological models, which assumes that topography mainly controls the water flow. While this applies in steep terrain, the assumptions of the kinematic wave do not apply in flatter landscapes. The Wflow framework is a free and open-source distributed hydrological modeling platform developed by Deltares (van Verseveld et al., 2022). The Wflow framework has been extensively tested in catchments around the world using the SBM vertical concept in combination with the kinematic wave for lateral river, overland flow and subsurface flow routing. Recently, the local inertial approximation, which only neglects the convective acceleration term in the Saint-Venant equations, was implemented in the Wflow framework as an alternative lateral routing concept to accurately represent river routing processes in flatter areas. In addition, the numerical scheme proposed by de Almeida et al. (2012) was implemented for the simulation of 2D overland flow. Using the HydroMT (Hydro Model Tools, https://github.com/Deltares/hydromt) Python package, we set-up wflow_sbm models for the Rhine and the Meuse basins and compare alternative concepts for river (and overland flow) routing, including kinematic wave, local inertial 1D and local inertial 1D2D. The results show significant differences in the shape and magnitude of modeled peak flows and the importance of floodplain storage and floodwave attenuation processes, as the local inertial 1D2D simulations were closest to streamflow observations. With this study, we stress the importance of including relevant routing processes (floodwave attenuation through overbank flow in the floodplains) as opposed to a more extensive calibration which would compensate for these lacking processes.

 

References:

de Almeida, G. A. M., P. Bates, J. E. Freer, and M. Souvignet, 2012, Improving the stability of a simple formulation of the shallow water equations for 2-D flood modeling, Water Resour. Res., 48, W05528, https://doi.org/10.1029/2011WR011570.

van Verseveld, W. J., Weerts, A. H., Visser, M., Buitink, J., Imhoff, R. O., Boisgontier, H., Bouaziz, L., Eilander, D., Hegnauer, M., ten Velden, C., and Russell, B.: Wflow_sbm v0.6.1, a spatially distributed hydrologic model: from global data to local applications, Geosci. Model Dev. Discuss. [preprint], https://doi.org/10.5194/gmd-2022-182, in review, 2022.

How to cite: Bouaziz, L., Buitink, J., van Verseveld, W., Eilander, D., Hegnauer, M., Sprokkereef, E., Stam, J., van der Sleen, N., and Lammersen, R.: Comparing river routing concepts in distributed hydrological modeling, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-14263, https://doi.org/10.5194/egusphere-egu23-14263, 2023.

Conceptual hydrological models can play an important role in real-time river forecasting systems due to their limited calculation time and versatility. Nevertheless, their simplified structure, very often based on the water content in multiple storages, and constrained physical background hampers their applicability in seasonally influenced catchments. In particular, these models often show good forecasting performance in one season (e.g. for high discharges in wet seasons), but fail to capture events in other seasons (e.g. due to typical high intensity precipitation during dry periods). To overcome this issue, we propose a seasonal calibration approach for conceptual hydrological models, based on the results of a seasonal sensitivity analysis. The obtained seasonal models however induce an additional challenge within a continuous real-time river forecasting system: the transition from one seasonal model to another. The latter is of particular importance when the volume of the storages in the conceptual model changes between different seasons. An application with the conceptual NAM model for three catchments in Belgium will be used to illustrate the proposed calibration strategy and a number of possible solutions for the transition issue.

How to cite: Nossent, J. and Nsubuga, R.: A seasonal calibration approach of conceptual hydrological models for improved real-time river forecasting, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-14378, https://doi.org/10.5194/egusphere-egu23-14378, 2023.

Intensive Soil and Water Conservation (SWC) has taken place in the Yellow River basin (YRB) to control soil erosion and river sediment, it has altered the eco-hydrological processes and particularly led to the runoff reduction. However, the SWC are rarely simulated explicitly in the hydrological models of the YRB. In order to understand its hydrological impacts, this study developed a SWC parameterization scheme in an existing distributed physically-based model (GBEHM). The hillslope SWC was parameterized as additional surface storage capacity and simulated together with hillslope hydrological processes. The check dams along the river networks were parameterized as reservoirs and simulated together with the flow routing. The improved model (GBEHM-SWC) had been calibrated and validated comprehensively using the observed river discharge and remote sensing-based evapotranspiration. The annual precipitation and runoff significantly decreased during 1982-2000 at the rate of -4.3 and -1.0 mm/yr, respectively. In the following period 2001-2019, the precipitation recovered at 3.2 mm/yr with a slight increasing in runoff at 0.2mm/yr. Compared to the previous period, the annual average precipitation and temperature increased by 27.3 mm and 0.85 ℃, whereas the observed runoff decreased by 4.3 mm. Therefore, we applied the GBEHM-SWC to quantify the impacts of climate change and SWC in the YRB, spatially and temporally. The SWC contributed to the annual runoff reduction by 3.8 and 3.7 mm (or 2.84 and 2.74 billion m3), respectively, in which the hillslope SWC measures accounted for 51% of the annual runoff reduction. Without the append SWC measures, the annual runoff would increase by 2.9 mm (or 2.17 billion m3) in the recent period due to the precipitation increase. Hillslope SWC and river-networks SWC have their largest impact on runoff reduction in the Longmen-Sanmenxia section and Toudaoguai-Longmen section, respectively. The parameterization scheme developed for the distributed model is useful for the watershed hydrological simulation and prediction under the intensive SWC implementation.

How to cite: Yan, Z., Lei, H., Yang, D., and Gao, H.: Simulating the hydrological impacts of intensive Soil and Water Conservation Measures in the Yellow River Basin Using a Distributed Physically-based Model, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-15058, https://doi.org/10.5194/egusphere-egu23-15058, 2023.

EGU23-15217 | ECS | Posters on site | HS2.2.1

EDCHM: A c++ based R package for flexible semi-distributed conceptual hydrological modeling 

Kan Lei, Diana Spieler, and Niels Schütze

Modular hydrological modeling has been around for some time, with early examples such as the Modular Modeling System (MMS) developed in 1996. In 2011,Fenicia et al. introduced the SUPERFLEX modeling framework, refined by Molin et al. (2021) as the Python package SurperflexPy. A framework with an even larger library of processes is the Raven modeling framework introduced by Craig et al. (2020).

This work introduces a c++ based R package prioritizing convenience while still offering flexibility for semi-distributed hydrological modelling. The EDCHM framework defines five basic layers: atmosphere, snow pack, land, soil, and ground, with the soil and ground layers able to be further divided into sublayers. Each layer has its own characteristics and state variables such as capacity and water volume. EDCHM defines 12 basic processes, including 10 hydrological and 2 meteorological processes such as evapotranspiration and infiltration. Each process has a single flux output, and it can occur within a single layer or between layers. The input requirements are flexible and depend on the specific method used. A process with a specific method is referred to as a module in EDCHM. EDCHM also includes 34 predefined model structures with fixed connections between processes and layers, ranging from 6 to 15 processes. The key feature of EDCHM is the model builder, which allows users to easily generate the model function just by selecting the process methods, the input data list, and the parameter list with ranges will also be created. This makes it fast and efficient for users to build and calibrate models. EDCHM is implemented in c++ and supports vectorization and parallelization through R-Package Rcpp and furrr. Users can easily build new models with their own ideas or ideas from literature.

EDCHM has been tested on 34 east-german catchments, with over 60 models calibrated in lumped form and 6 catchments calibrated with 3 and 5 sub-catchments or more than 50 HRUs. Our results show that EDCHM is highly effective in the application of hydrological modeling, with a key feature being its efficiency.

 

Craig et al. (2020). https://doi.org/10.1016/j.envsoft.2020.104728

Fenicia et al. (2011). https://doi.org/10.1029/2010WR010174

EDCHM: https://github.com/LuckyKanLei/EDCHM

How to cite: Lei, K., Spieler, D., and Schütze, N.: EDCHM: A c++ based R package for flexible semi-distributed conceptual hydrological modeling, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-15217, https://doi.org/10.5194/egusphere-egu23-15217, 2023.

Hydrological models are powerful tools, that allows users to create a simplified representation of real-world system and that serve to understand the hydrological processes in a basin, and predict their future behavior, including, for example, the effects of climate change. However, these models are subject to multiple sources of uncertainty, including structural uncertainty, related to the hydrological processes simulated and to the spatial discretization applied (lumped, semi-distributed or distributed models). The effects of this modelling decision could be particularly relevant when the objective is to simulate more than one hydrological process.

The objective of this work is to determine if the use of different model structures (lumped or semi-distributed), and the selection of process to be simulated allows reducing the uncertainty of the estimation of more than one hydrological process. Using Raven, a robust and flexible hydrological modelling framework, that supports a wide variety of modelling options, and sits atop a robust and extendible software architecture, eight model structures have been constructed to simulate the River Colorado en Junta con Palos Basin. This basin located in the central zone of Chile (Lat.-35.25, Lon. 71), has a snow-pluvial regime and an average annual rainfall of 1796 mm for the period 1979-2020.  Additionally, this basin covers an area of 879 km2, with a wide elevation range, from 643 m.a.s.l. to 4074 m.a.s.l.

The results have shown some differences at modelling daily streamflow (KGE from 0.68 to 0.72 in the lumped models, and from 0.68 to 0.8 in semi-distributed models). Furthermore, other important changes have been visualized related to the characterization of snow cover and soil moisture in the first layer of soil. The simulated series have been compared to satellite data (products MODIS10A2 for snow cover and NASA-USDA Enhanced SMAP Global Soil Moisture Data for superficial soil moisture).

In the case of the snow cover, the annual duration of snow cover was evaluated, obtaining Pearson's coefficient values between 0.4 and 0.56 for lumped models, while these values reach 0.65 in the case of semi-distributed models. Regarding soil moisture, the changes were more significant when changing the structure of the model (selection and parameterizations of the processes), rather than its spatial discretization, with a range of KGE values from 0.34 to values close to 0.7, strongly influenced by the methods used to evaluate evapotranspiration and infiltration, as well as by the characteristics of the soil.

Overall, this work demonstrates the potential of a flexible hydrologic modeling framework to assess and reduce the structural uncertainty of hydrologic models, taking advantage of the potential of these tools.

How to cite: Rodriguez, P. and Vargas, X.: Evaluation of the structural uncertainty of hydrological models in the estimation of multiple hydrological processes, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-15920, https://doi.org/10.5194/egusphere-egu23-15920, 2023.

EGU23-3 | Posters virtual | HS2.2.5

Runoff characterisation by SEC measurements in spring water 

Elke Bozau and Tobias Licha

Extreme weather periods in the Harz Mountains with heavy rain events (e.g., July 2017) and long dry periods (September 2016, May – November 2018, September 2020) trigger extreme changes in surface runoff. However, such events do not lead to unknown, unpredictable chemical changes of the spring water in the Upper Harz Mountains (Bozau et al., 2013 and 2021). In order to obtain more information on the chemical evolution and to predict drying out events, spring waters of several catchment areas of the Harz Mountains were monitored. Every spring has a typical runoff pattern combined with specific chemical variations. The order of drying out during long droughts depends on the catchment size of the individual spring and did not change in the observation period.

Since February 2020, the specific electrical conductivity (SEC) of the spring "Innerstesprung" near Clausthal has been systematically measured at least once a week. This spring has its source in fractured Paleozoic greywacke, flows at the surface for about 30 m in a little artificial channel and then passes into the reservoir lake "Entensumpf". The measured SEC data are compared with daily precipitation rates. Drying out and first flush events show specific SEC trends. Furthermore, frozen snow covers are reflected by the SEC data. The SEC values of the spring water range between 55 and 100 µS/cm. Minimum values are typical for long rainy periods and snow melt in February. Only in 2017 (with about 300 mm precipitation during one week of July) 57 µS/cm were found in summer time. The maximum values of SEC are measured immediately before the drying out of the spring. Furthermore, a special effect of SEC enrichment after the first flush event has been observed. An impact of the enhanced deforestation which started in 2020 was not seen during the monitoring period. The spring runoff, precipitation and evaporation rates during the drying out events can be used for the calculation of the catchment areas. Furthermore, water-rock interactions along the flow path of spring water were investigated by batch tests.

References:

Bozau, E., Stärk, H.-J., Strauch, G., 2013. Hydrogeochemical characteristics of spring water in the Harz Mountains, Germany. Geochemistry, 73, 283-292.

Bozau, E, Bauer, G., Licha, T., Lojen, S., 2021. Hydrochemical response of spring and mine waters in the Upper Harz Mountains (Germany) after dry periods and heavy rain events. ZDGG, 172(1), 73-82.

How to cite: Bozau, E. and Licha, T.: Runoff characterisation by SEC measurements in spring water, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-3, https://doi.org/10.5194/egusphere-egu23-3, 2023.

EGU23-348 | ECS | Posters on site | HS2.2.5

Detecting the occurrence of preferential flow in soils with stable water isotopes 

Jonas Pyschik and Markus Weiler

Preferential flow in soils and hillslopes may transport water faster than the soil matrix. These features activate quickly during precipitation events, increase infiltration and vertical pathways can play an important role in runoff generation. However, preferential pathways are difficult to identify as common techniques (e.g. piezometer, soil moisture sensors, hillslope trenches) do not sufficiently represent the spatial scale and frequency of these features and other approaches (e.g. dye patterns) are labour intensive and heavily invasive.

Here, we present a method to derive locations of preferential flow only by using vertical stable water isotope profiles in soils. In four catchments, we each drilled 120 soil cores (1-3m) and analysed the stable isotope composition of the soil water in 10-20cm increments to derive depth profiles. Visually selecting profiles with similar isotopic seasonality patterns not influenced by preferential flow, we determined a reference isotope profile for each catchment using a LOESS regression. These represent a soil profile only influenced by vertical matrix infiltration. To account for differences in soil conductivity and porosity, the reference profiles were scaled by depths to each profile. Locations where the measured profile deviates significantly from the reference, we assume an influence of vertical or lateral preferential flow.

With this method we found evidence for preferential flowpaths in all catchments. Especially in the alpine catchment with highly heterogeneous soils many profiles showed distinct preferential flow features. There, some profiles also indicate multiple, vertically independent pathways. The depth at which these pathways occurred were highly variable, even at neighbouring profiles.

Overall our results demonstrate the feasibility to assess preferential flow only using soil water isotope profiles while also underlining the large spatial and vertical variability of preferential flowpaths at the hillslope and catchment scale.

How to cite: Pyschik, J. and Weiler, M.: Detecting the occurrence of preferential flow in soils with stable water isotopes, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-348, https://doi.org/10.5194/egusphere-egu23-348, 2023.

EGU23-2784 | ECS | Orals | HS2.2.5

Combining land surface modelling and Earth observations: the key role of soil moisture data to improve estimates of agricultural water uses 

Sara Modanesi, Gabriëlle J. M De Lannoy, Michel Bechtold, Luca Brocca, Jacopo Dari, Louise Busschaert, Martina Natali, and Christian Massari

Soil moisture is an essential climate variable and the main driver for water exchanges between the land surface and the atmosphere. An accurate knowledge of the soil moisture conditions is also crucial to estimate the amount of water needed or used for agricultural purposes.

As human demand for water is increasing along with extreme drought events, an optimal agricultural management is paramount to cope with a drier and warmer future, e.g. in Mediterranean regions. Thus, the knowledge of soil moisture is central for monitoring agricultural drought, optimizing agricultural water uses (i.e., irrigation) and improving the water cycle and land-atmosphere processes understanding. Nevertheless, the point-based nature and limited spatial coverage of in situ soil moisture observations in conjunction with the poor parameterization of human processes in earth system models (i.e., unmodelled or wrongly modelled irrigation), undermine the ability to accurately monitor and forecast drought events as well as the capacity to safely manage water resources.

Remote sensing observations offer a unique opportunity to fill these gaps as they can directly observe the processes of the plant-soil continuum. Here we provide insights on the value of satellite-based soil moisture and soil moisture-related measurements (i.e, radar backscatter) for land surface models and for agricultural drought research. We will show the utility of both classical coarse-scale and new high resolution observations for a number of applications that span from irrigation estimation, crop yield analysis, improvement of water cycle processes to estimation of small scale soil moisture variability across agricultural and mountaineous European pilot sites.

How to cite: Modanesi, S., De Lannoy, G. J. M., Bechtold, M., Brocca, L., Dari, J., Busschaert, L., Natali, M., and Massari, C.: Combining land surface modelling and Earth observations: the key role of soil moisture data to improve estimates of agricultural water uses, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-2784, https://doi.org/10.5194/egusphere-egu23-2784, 2023.

Accurate measurements and estimates of evapotranspiration (ET) and soil moisture are essential for efficient crop management and understanding of hydrological processes in agricultural catchments. In this study, we used satellite imagery for a small catchment (Nučice, Czech Republic) to retrieve vegetative indices (VIs, including NDVI, SAVI and EVI), hence to analyse their spatial and temporal variability. Furthermore, we investigated the relationship between vegetative indices (VIs), measured evapotranspiration (ET), and soil water storage (SWS). Also, for each variable, we aggregated weekly data at the seasonal temporal resolution, being able to study the trends of each variable’s statistical moments. Moreover, we employed the Normalized Nash-Sutcliffe Efficiency (NNSE) index to study the error and the bias between normalized variables within the same seasonality. We found linear relationships between VIs, ET, and SWS when they exceeded a certain threshold. We were able to estimate the ET by exploiting its linear relationships with VIs and SWS, thus bridging the measurement gap. Our results suggest ET prediction based on VIs can be used during the growing season but may give inaccurate results after harvest (when VIs have low values). SWS can provide a reasonable estimate of the ET when no vegetation is present. Furthermore, the good correspondence between the seasonal NNSE indices and the trends of statistical moments of ET, VIs, and SWS suggest that subsurface processes might be inferred from seasonal vegetation cover. Therefore, this allows us to anticipate the likelihood of seasonal correlations across surrogate variables, further studying the spatial variations of SWS throughout the catchment in connection to ET and VIs.

This research has been supported by the Grant Agency of the Czech Technical University in Prague, Grant No. SGS20/156/OHK1/3T/11 and TUdi project, EU Horizon 2020 Grant Agreement No 101000224.

 

How to cite: Li, T., Schiavo, M., and Zumr, D.: Mutual relationships between evapotranspiration and soil water storage in a small agricultural catchment and their consistency from a statistical viewpoint, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-3298, https://doi.org/10.5194/egusphere-egu23-3298, 2023.

EGU23-3658 | ECS | Orals | HS2.2.5

Harnessing integrated hydrologic modeling to analyze the coastal impacts of groundwater-surface water interactions on beach surface stability and freshwater availability 

Anner Paldor, Ryan S. Frederiks, Rachel Housego, Britt Raubenheimer, Steve Elgar, Nina Stark, and Holly A. Michael

Coastal aquifers supply freshwater to nearly half of the world's population, and their importance for sustainable development in coastal areas is immense. Due to the proximity to the ocean, salinization is typically the biggest risk for coastal groundwater resources. Furthermore, the interactions between groundwater and surface water during coastal flooding often result in surface instabilities arising from elevated groundwater heads. Here, integrated hydrologic modeling is used to examine the effect of groundwater-surface water interactions on the salinity distribution in aquifers and on the stability of beach surfaces. The processes considered include multi-scale fluctuations in sea level (tides, storm surges, and glacial cycles). Results show that modern salt distributions may change even if the current conditions remain stable, when considering short- and long-term cyclical processes that aquifers are likely still responding to. It is also found that during coastal flooding, critical hydraulic gradients may develop, potentially destabilizing the beach surface. The distribution of these critical gradients depends on beach topography, with a non-trivial relationship between surface elevation and the location of critical gradients. These results mean that the interactions between groundwater and surface water likely play a pivotal role in the hydrologic state of coastal systems, with important implications for water resources management and for natural hazard mitigation.

How to cite: Paldor, A., Frederiks, R. S., Housego, R., Raubenheimer, B., Elgar, S., Stark, N., and Michael, H. A.: Harnessing integrated hydrologic modeling to analyze the coastal impacts of groundwater-surface water interactions on beach surface stability and freshwater availability, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-3658, https://doi.org/10.5194/egusphere-egu23-3658, 2023.

EGU23-4085 | ECS | Posters on site | HS2.2.5

Data-guided exploration of streamflow generation mechanism: A global-scale analysis 

Hamed Sharif and Ali Ameli

Identifying a catchment’s streamflow generation mechanisms could inform the hydrologic functioning of the catchment, and how the catchment responds to the changes in climate and land-use. This study focuses on identifying the dominant streamflow generation mechanism and its drivers at more than 2,000 natural catchments located in North and South America, Europe, and Oceania. First, in a given catchment, we use a suite of diagnostic tools to infer the relative contribution of different streamflow generation mechanisms from precipitation and streamflow observations and simulated time series of subsurface storage. Then, in a large sample hydrology framework, we explore the major physical and climatic drivers of streamflow generation mechanisms. In this study, we made progress in differentiation among, seemingly similar, but naturally different subsurface mechanisms of streamflow generation (e.g., subsurface stormflow, transmissivity feedback, groundwater flow) as well as in identifying the drivers of these mechanisms. Our study extracts generalizable process understanding by combining conventional hydrologic science tools with modern data learning techniques.

How to cite: Sharif, H. and Ameli, A.: Data-guided exploration of streamflow generation mechanism: A global-scale analysis, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-4085, https://doi.org/10.5194/egusphere-egu23-4085, 2023.

EGU23-4973 | Orals | HS2.2.5

The International Soil Moisture Network - a global interoperable data center for in situ soil moisture observations 

Fay Böhmer, Tunde Olarinoye, Wolfgang Korres, Kasjen Kramer, Stephan Dietrich, Matthias Zink, Irene Himmelbauer, Lukas Schremmer, Ivana Petrakovic, Daniel Aberer, Roberto Sabia, Raffaele Crapolicchio, Philippe Goryl, Klaus Scipal, and Wouter Dorigo

Soil moisture is recognized as an Essential Climate Variable (ECV), because it is crucial to assess water availability for plants and hence food production. Having long time series of freely available and interoperable soil moisture data with global coverage enables scientists, farmers and decision makers to detect trends, assess the impacts of climate change and develop adaptation strategies.

The collection, harmonization and archiving of in situ soil moisture data was the motivation to establish the International Soil Moisture Network (ISMN) at the Vienna University of Technology in 2009 as a community effort. Based on several project funding periods by the European Space Agency (ESA), the ISMN became an essential means for validating and improving global land surface satellite products, climate and hydrological models.

Permanent funding for the ISMN operations was secured through the German Government (Ministry of Digital and Transport) and therefore the ISMN has successfully migrated at the end of 2022 to its new host the International Centre for Water Resources and Global Change (ICWRGC) and the German Federal Institute of Hydrology (BfG). Furthermore, the ISMN was recognized by WMO in their latest State of Global Water Resources report.

To improve the data service delivery, ISMN users can now benefit from a newly developed dataviewer which features functionalities such as data archives and advanced filter options (e.g. for climate and landcover types, for data quality) developed in synergies with the ESA project Fiducial Reference Measurements for Soil Moisture (FRM4SM). This presentation aims at showcasing these latest upgrades as well as new network contributions to the ISMN.

How to cite: Böhmer, F., Olarinoye, T., Korres, W., Kramer, K., Dietrich, S., Zink, M., Himmelbauer, I., Schremmer, L., Petrakovic, I., Aberer, D., Sabia, R., Crapolicchio, R., Goryl, P., Scipal, K., and Dorigo, W.: The International Soil Moisture Network - a global interoperable data center for in situ soil moisture observations, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-4973, https://doi.org/10.5194/egusphere-egu23-4973, 2023.

EGU23-5130 | ECS | Posters on site | HS2.2.5

Tracking water movement through a small agricultural catchment using StorAge Selection functions  and hydrologic modeling 

Hatice Türk, Markus Hrachowitz, Karsten Schulz, Christine Stumpp, Michael Stockinger, Peter Strauss, and Günter Blöschl

 

Determining the processes that drive streamflow generation and catchment-scale transport of nutrients and pollutants by water is one of the challenges of modern hydrology. In the last decades, substantial knowledge has been gained from high-frequency and high-resolution measurements of tracers to track water movements within a hydrological system. For example, the stable isotopes of oxygen (d18O) and hydrogen (d2H) have been widely used to disentangle the contributions of different runoff generation mechanisms by modeling water travel and residence times. However, quantifying the effects of catchment internal factors for similar or different transit time distributions, particularly in characteristically complex and heterogeneous catchments, remains a challenge. Here we test different shapes for age selection functions (StorAge Selection) of individual distinct storage components (e.g., the root zone, groundwater) of the agricultural Hydrological Open Air Laboratory (HOAL) catchment in Petzenkirchen, Austria. The HOAL has a variety of runoff generation mechanisms, including overland flow, wetlands, and tile drains, as well as high-resolution tracer and hydrological data that allows for broad storage-discharge relationship testing. The main goal of this study is to estimate the transit time distributions associated with varying fluxes from these components (e.g., overland flow, groundwater recharge) to learn about catchment internal streamflow generation processes. Water flow is modeled with a water age balance model and are replaced by selecting the appropriate transfer functions. Testing different age selection functions for various storage components of the catchment will provide a better understanding of catchment dynamics under different environmental conditions, allowing for better calibration of catchment-scale water and nutrient transport models.

 

 

How to cite: Türk, H., Hrachowitz, M., Schulz, K., Stumpp, C., Stockinger, M., Strauss, P., and Blöschl, G.: Tracking water movement through a small agricultural catchment using StorAge Selection functions  and hydrologic modeling, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-5130, https://doi.org/10.5194/egusphere-egu23-5130, 2023.

EGU23-6098 | ECS | Posters virtual | HS2.2.5

Assessment of the impact of soil hydraulic parameters based on various Microwave datasets on estimation of hydrological fluxes 

Vikrant Maurya, Manika Gupta, Juby Thomas, Prashant Kumar Srivastava, Dharmendra K. Pandey, Naresh Chandra Pant, and Atul Kumar Sahai

Soil Moisture (SM) is a key variable in the quantification of the water and the energy-balance fluxes occurring within the atmosphere and the surface. Recent advances in microwave remote sensing provide an unprecedented opportunity to monitor surface soil moisture globally but at a coarse (~25-40 km) spatial resolution. Although hydrological models based on water and energy fluxes are also used for estimation of the high spatial resolution soil moisture at regional scale to understand the surface hydrological processes, agricultural applications, and the water resource management remains a challenge as it depends upon hydraulic parameters. Therefore, the study focuses on the assessment of the impact of the downscaled SM derived from different microwave datasets on optimized soil hydraulic parameters and eventually its effect on discharge at the basin scale. The aim is achieved in two steps: firstly, the coarse scaled SM products from different microwave datasets (Advanced Microwave Scanning Radiometer 2 (AMSR-2) and Soil Moisture Active Passive (SMAP)) are downscaled to 1km spatial resolution using a disaggregation algorithm. Secondly, effective soil hydraulic parameters are optimized with dual input of downscaled SM and the discharge for the Kosi Basin. The results show that there is a significant impact of the optimization of soil hydraulic parameters on the hydrological fluxes and discharge. The effective soil hydraulic parameter derived from the downscaled product of SMAP L3 shows a promising result in simulation of SM from hydrological model in addition to that the optimization technique using GA in the hydrological models ensures a better process representation and spatial prediction.

How to cite: Maurya, V., Gupta, M., Thomas, J., Srivastava, P. K., Pandey, D. K., Pant, N. C., and Sahai, A. K.: Assessment of the impact of soil hydraulic parameters based on various Microwave datasets on estimation of hydrological fluxes, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-6098, https://doi.org/10.5194/egusphere-egu23-6098, 2023.

EGU23-6635 | ECS | Posters on site | HS2.2.5

The riparian zone as a gatekeeper for subsurface stormflow 

Alexey Kuleshov, Anne Hartmann, Theresa Blume, and Maria-Luisa Hopp

Subsurface stormflow (SSF) can be a major streamflow generation process in small catchments. It is known that SSF generated on the hillslopes of the catchment may change both in its chemical and quantitative composition on the way to the stream. This occurs primarily due to processes in the riparian zone. The riparian zone plays the role of a "reactor" where mixing, storage, and biogeochemical transformation of the hillslope SSF composition occurs.  However, we still lack a comprehensive understanding of this “gatekeeper function” of the riparian zone, controlling the timing and spatial patterns of connectivity and the chemistry of the water being transferred from the hillslopes into the stream.
In our study we aim to investigate the SSF signal transformation in the riparian zone. We installed three “dual-use trenches” per catchment in four different catchments located in Germany and Austria. With this novel dual-use trench approach we are able to measure hillslope SSF as well as inject tracer into the riparian zone. We measure response dynamics, timing, flow volumes and chemistry at the upslope side of the trench. We will identify tracers or tracer combinations that characterize SSF and can be used to identify hillslope SSF in riparian zone groundwater and stream flow. The inter-comparison of the four different catchments allows us to evaluate the influence of landscape and climate characteristics. We then use tracer injections at the downslope side of the dual-use trench in combination with an array of shallow groundwater observation wells downslope of the trench to investigate the physical and chemical transformation of hillslope SSF in the riparian zone. This array of wells extends both upstream and downstream of the trench, enabling us to trace the transformation of the uninterrupted physical and chemical signal of SSF on the adjacent hillslopes on its passage to the stream and to evaluate the influence of parafluvial flow.
Here, we present first data on tracer concentrations in hillslope SSF and riparian zone groundwater from our test catchments. Ultimately, we aim to develop a conceptual matrix, by which it will be possible to estimate the degree of SSF transformation in the riparian zone, depending on watershed characteristics (topography, soil depth and soil hydraulic properties) and hydrological conditions (antecedent wetness of the watershed and seasonal dynamics).

How to cite: Kuleshov, A., Hartmann, A., Blume, T., and Hopp, M.-L.: The riparian zone as a gatekeeper for subsurface stormflow, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-6635, https://doi.org/10.5194/egusphere-egu23-6635, 2023.

Soil moisture measurements are very popular. Yet they provide a very incomplete picture about the state of the partially saturated zone and the capillary binding of soil water. Here we propose that the free energy of the soil water stock offers a superior perspective on storage dynamics, as it combines soil water content, gravity potential and matric potential data. Based on this new state variable, we show that the partially saturated zone is characterized by a system-specific balance of storage and release corresponding to local state of minimum free energy. The latter depends on the soil water retention curve and topography/depth to groundwater. In the absence of an external rainfall or radiative forcing, the system will thus naturally relax back to and persist in this equilibrium. Hydrological systems are however not isolated, they are frequently forced out of their equilibrium either by rainfall or by radiation driven evaporation. Here we show that the corresponding storage dynamics manifests as deviations of the free energy from and relaxations back the local equilibrium and that the latter separates two different regimes, which are either associated with a storage excess and overshoot of potential energy or a storage deficit and overshoot of capillary binding energy. We demonstrate that these pseudo oscillations are distinctly different in different hydrological landscapes. As the free energy state of the soil water stock, the storage equilibrium and the ranges of both storage regimes depend jointly on depth to groundwater and the soil water retention curve, we combine both controls into a hydrological system characteristics we call the ‘energy state function’ of the soil. We show that the latter allows an insightful inter-comparison of storage dynamics with in different hydrological landscapes, and a priory estimate of depth to groundwater, based on available soil moisture and matric potential data. Finally, we demonstrate a threshold-like relation between the free energy of soil water in the riparian zone and streamflow generation, where the tipping points coincides with the transition from a storage deficit to a storage excess.

How to cite: Zehe, E., Hoffmeister, S., and Loritz, R.: Free energy of soil water – a superior perspective on storage dynamics and its sensitivity to soil hydraulic properties and topography, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-6735, https://doi.org/10.5194/egusphere-egu23-6735, 2023.

EGU23-7917 | ECS | Posters on site | HS2.2.5

Towards a robust parameterization of subsurface stormflow in hydrological models at the catchment scale 

Tamara Leins, Francesca Pianosi, and Andreas Hartmann

In addition to overland flow, subsurface stormflow (SSF) can play a major role for runoff generation during certain events. Even though SSF is a well-recognised process, there is a lack of systematic studies on SSF, partly because it is very difficult to quantify. In hydrological modelling, this can lead to an unclear distinction of SSF from other processes. If parameters that describe SSF processes or thresholds are implemented in hydrological models, they are often used as fitting parameters and can contribute to overall model uncertainty. So far, there has been no systematic benchmarking of SSF routines in hydrological models.

This presentation discusses how we plan to address this research gap. In order to address the inconsistency of SSF representation in hydrological models, different existing lumped hydrological models will be set up for four study sites located in the Alps, Ore Mountains, Black Forest and Sauerland. In a first step, different models will be calibrated using only basic data like discharge observations, climate data and readily available geodata. Differences in SSF simulations will be detected and quantified and the models will be benchmarked regarding the simulation of SSF dynamics and associated uncertainties. In a next step, we will include new experimental data on SSF derived at the four study sites in the calibration of the lumped hydrological models by a multi-objective calibration and evaluation framework. In order to consider SSF observations collected at scales different than the scale of model application, new SSF metrics will be developed. Testing different combinations of these metrics for model calibration it will be possible to state which SSF proxies can lead to the most productive improvement of SSF simulations.

Identifying current weaknesses in SSF representation of current models, and providing directions for improving them by including the most beneficial SSF metrics, this project will show potential for the improvement of SSF simulations through SSF data collection. In a final application of the most reliable SSF simulations to all study sites, we will show the impact of extreme wet or extreme dry conditions on SSF occurrence and SSF volumes.

How to cite: Leins, T., Pianosi, F., and Hartmann, A.: Towards a robust parameterization of subsurface stormflow in hydrological models at the catchment scale, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-7917, https://doi.org/10.5194/egusphere-egu23-7917, 2023.

EGU23-8754 | Orals | HS2.2.5

Assimilation of SMAP surface soil moisture retrievals into the FAO crop growth model AquaCrop v7.0 

Michel Bechtold, Louise Busschaert, Shannon de Roos, Zdenko Heyvaert, Sujay Kumar, Jonas Mortelmans, Samuel Scherrer, Maxime Van den Bossche, Dirk Raes, Elias Fereres, Margarita Garcia-Vila, Pasquale Steduto, Theodore Hsiao, Maher Salman, and Gabrielle De Lannoy

Recently, the FAO crop model AquaCrop v7.0 has been released as open-source code along with the standard graphical user interface for single field applications, and Linux, Windows, and Mac stand-alone executables for plugin into regional or climate simulations (https://www.fao.org/aquacrop/en/). In addition, AquaCrop v7.0 has been coupled as the first crop model into NASA’s Land Information System (LIS) to support regional modeling and data assimilation (DA) using spatially complete re-analysis meteorological forcings, and to produce spatio-temporally complete geolocated NetCDF output for the first time. This presentation explores the potential of soil moisture updating for improving crop growth model estimates of AquaCrop.

Our DA setup uses the one-dimensional ensemble Kalman filter to assimilate the SMAP Level-2 surface soil moisture retrieval product from April 2015 through 2021 on a quarter-degree regular model grid over Europe. Prior to assimilation, a climatological rescaling is applied to remove the observation-minus-forecast bias. A preliminary evaluation against in-situ data of the International Soil Moisture Network indicates that topsoil (0-30 cm) soil moisture estimates of AquaCrop are improved through the DA compared to the model-only estimates. Our results show that the adjusted soil moisture strongly modulates biomass accumulation during the main growing period from April to June, particularly over moisture-limited areas. The impact on biomass will be further evaluated with the Copernicus Global Land Service dry matter productivity product as the observational reference.

How to cite: Bechtold, M., Busschaert, L., de Roos, S., Heyvaert, Z., Kumar, S., Mortelmans, J., Scherrer, S., Van den Bossche, M., Raes, D., Fereres, E., Garcia-Vila, M., Steduto, P., Hsiao, T., Salman, M., and De Lannoy, G.: Assimilation of SMAP surface soil moisture retrievals into the FAO crop growth model AquaCrop v7.0, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-8754, https://doi.org/10.5194/egusphere-egu23-8754, 2023.

EGU23-8815 | Orals | HS2.2.5

Inverse identification of soil properties at catchment scale via pilot point calibration of an integrated surface-subsurface hydrological model 

Arkadiusz Głogowski, Wiesław Fiałkiewicz, Oliver Schilling, and Philip Brunner

For water managers, extreme weather events such as droughts and heavy rainfall can pose severe challenges. Both sudden and longer term surpluses or shortages of water are operationally challenging to deal with. Investigating the effects of extreme hydrological events at the catchment scale requires the development of hydrological models capable of simulating such events. The present study is focused on developing such a model for an agricultural catchment using the integrated surface-subsurface hydrological flow model (ISSHM) HydroGeoSphere. For robust simulation of the impact of heavy rainfall and drought events on water availability and crops, an accurate representation of the spatially highly variable soil hydraulic properties has been identified as crucial. To identify effective soil hydraulic properties at the catchment scale, we propose a method combining real time observations of soil moisture, groundwater levels and catchment outflow with an ISSHM of the catchment via pilot point-based model inversion. The applicability of the method is demonstrated on a 17 km2 tributary agricultural catchment of the Odra River located 20 km north of Wrocław, Poland. The validation data for the approach consist of soil samples analysed both before and after the vegetation period.

How to cite: Głogowski, A., Fiałkiewicz, W., Schilling, O., and Brunner, P.: Inverse identification of soil properties at catchment scale via pilot point calibration of an integrated surface-subsurface hydrological model, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-8815, https://doi.org/10.5194/egusphere-egu23-8815, 2023.

EGU23-8875 | ECS | Posters on site | HS2.2.5

Tracing Longitudinal Patterns of Subsurface Hillslope-Stream Connections Across Catchments 

Natasha Gariremo, Luisa Hopp, and Theresa Blume

Subsurface stormflow (SSF) generated on hillslopes is an important hydrological process in headwater catchments. Tracing SSF flow paths and ultimately quantifying its contribution to streamflow is challenging as the signal can undergo various transformations from the hillslope. The riparian zone specifically, can act as a mixing and storage zone and may change strongly the physical and chemical signals of hillslope SSF before it reaches the stream. As a consequence, SSF may not be recognized as streamflow contribution. Thus, the relevance of this process for streamflow generation is currently not fully understood. In addition, studies often focus on quantifying SSF generation at the hillslope scale. Therefore, there is a lack of data to fully understand SSF characteristics at the catchment scale.

The aim of this study is to characterize the hillslope-stream connectivity at the reach to catchment scale, using physical as well as chemical information. To deal with the challenges associated with measuring the SSF signal, this study implements a novel multi-method experimental design that will create a unique along-stream data set of hillslope contributions to streamflow in four test catchments in Germany and Austria. A combination of extensive salt dilution gauging along streams, water level measurements in-stream and in near-stream groundwater, longitudinal Radon profiles in streamwater and regular sampling of near-stream groundwater and streamwater for hydrochemical analyses will allow to evaluate the spatial variability of SSF inputs to the stream and to quantify the along-stream attenuation of the SSF signal.

Here, we present the study outline as well as first data of water chemistry in near-stream groundwater and streamwater and will characterize the longitudinal patterns of a range of hydrochemical tracers along the streams in the four test catchments. The data set we will collect will be used to simplify and minimize future experimental effort and to identify simple proxies for regionalization. Ultimately, we aim to develop a framework to determine the likelihood of hillslope-stream connectivity at the catchment scale, as influenced by landscape and climate characteristics.

How to cite: Gariremo, N., Hopp, L., and Blume, T.: Tracing Longitudinal Patterns of Subsurface Hillslope-Stream Connections Across Catchments, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-8875, https://doi.org/10.5194/egusphere-egu23-8875, 2023.

EGU23-9868 | ECS | Orals | HS2.2.5

Model simplification to simulate groundwater recharge from perched gravel-bed braided rivers 

Antoine Di Ciacca, Scott Wilson, and Thomas Wöhling

Braided rivers are an important source of groundwater recharge in New Zealand. They consist of multiple temporary channels in a gravel environment and, as a consequence, their interactions with groundwater are complex and highly variable in space and time at different scales. Recently, the gravels of the contemporary braidplain of these rivers have been described and referred to as the ‘braidplain aquifer’. It is within this aquifer that hyporheic and parafluvial flows occur. In these systems, the groundwater recharge to the deeper regional aquifer is actually the water exchange between the braidplain and the regional aquifers. Some of these braided rivers are perched above the regional water level in their main losing section, which means that an unsaturated zone exists between the braidplain and regional aquifer. This complexity calls for the use of 3D fully integrated hydrological models to represent groundwater – surface water interactions in these environments. However, these complex models are very computationally intensive, which strongly limits their use in parameter inference and uncertainty quantification schemes as well as their applicability to regional scale problems.

We present a modelling framework that includes a 3D fully coupled HydroGeoSphere (HGS) model and several 2D cross-sectional HYDRUS-2D models (with 1, 2 and 3 layers). This framework aims at simplifying the model while ensuring the appropriate simulation of the groundwater recharge. We demonstrate our modelling approach on the relatively small Selwyn River. Piezometric data and groundwater recharge estimates derived from satellite photography were available for this river. First, stochastic simulations were performed using the 2D cross-sectional models and compared to observations in order to explore the validity of different subsurface conceptualizations and parameter values. Second, the selected conceptualization and parameter values were used to parameterize the 3D fully coupled HGS model. Third, the groundwater recharge simulated by the 3D and the 2D models were compared. Our results demonstrate that the observations can only be reproduced with a minimum of 3 distinct layers, with a lower permeability layer in the middle. Furthermore, this modelling exercise revealed the primary importance of the width and thickness of the braidplain aquifer as they determine the infiltration front width and the pressure head applied to the braidplain aquifer bottom, respectively. This shows that the properties, dimensions and water level in the subsurface are controlling the groundwater recharge from the perched braided river rather than the river characteristics. Moreover, we show that a 2D cross-sectional model can effectively replace the 3D fully coupled model to simulate groundwater recharge from the perched braided river and that this reduces the model run time by 3 orders of magnitude. Finally, some analytical equations, which can be easily implemented in regional groundwater models, were tested as a further simplification of the 2D model.

How to cite: Di Ciacca, A., Wilson, S., and Wöhling, T.: Model simplification to simulate groundwater recharge from perched gravel-bed braided rivers, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-9868, https://doi.org/10.5194/egusphere-egu23-9868, 2023.

EGU23-10152 | Posters on site | HS2.2.5

Grid resolution, time discretization, boundary condition, and other challenges in coupled surface/subsurface hydrological modeling 

Claudio Paniconi, Claire Lauvernet, and Christine Rivard

In this study we push the limits of a physics-based detailed model of surface water/groundwater interactions, CATHY, in order to explore numerical issues related to discretization, coupling, and scale effects. Regardless of the spatial scale of the model domain (field, hillslope, catchment, ...), the processes that are simulated by integrated models such as CATHY are characterized by different dynamic time scales across subsystems and thus require appropriate time stepping schemes. Accurate tracking (in a mass balance sense) of complex exchange fluxes is also a challenge. At larger spatial scales, concerns related to aspect ratio and mesh distortion can influence and constrain grid discretization choices. Across the land surface boundary, different options for representing boundary conditions can lead to widely varying model behaviors. Finally, model performance assessments can be highly sensitive to the response variables of interest. We will illustrate some of these challenges via test case simulations of a long (13 km) transect and a small (0.3 ha) hillslope.

How to cite: Paniconi, C., Lauvernet, C., and Rivard, C.: Grid resolution, time discretization, boundary condition, and other challenges in coupled surface/subsurface hydrological modeling, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-10152, https://doi.org/10.5194/egusphere-egu23-10152, 2023.

EGU23-10343 | ECS | Posters on site | HS2.2.5

Combined Effects of Geological Heterogeneity and Discharge Events on Groundwater and Surface Water Mixing 

Guilherme Nogueira, Daniel Partington, and Jan H. Fleckenstein

Exchange between stream water (SW) and groundwater (GW) is an important mechanism controlling water quality in river-corridors. Different works have already recognized the complex interactions between hydrological and geological characteristics for SW-GW exchange fluxes (EF). However, it remains unclear how EF and subsequent SW-GW mixing are affected by different discharge events (e.g., peak discharge magnitude and event duration) that take place within different geological settings (e.g., highly permeable sand units juxtaposed to low permeable silt units). Here, to assess the combined effects of geological heterogeneity and discharge events on the EF patterns and subsequent SW-GW mixing in riparian aquifers, we combined a fully-coupled 3D numerical model with a mixing cell routine using 35 binary sedimentary geological settings (covering five different sand to silt ratios in the alluvial aquifer material) and eight different hydrological scenarios. Our results indicate that geological heterogeneity at the reach-scale has secondary effects on EF patterns and on the resulting net EF, mainly affecting the EF magnitudes. While EF magnitudes increased with increasing sand fractions (and hydraulic conductivity (K) values), including geological heterogeneity in the model generally enlarged SW infiltration, resulting in slightly higher net EF in comparison to the equivalent K homogenous cases. In general, SW-GW mixing under baseflow conditions decreased with increasing sand fractions. Furthermore, mixing was higher in the equivalent homogenous cases (e.g., similar K values) in comparison to the heterogeneous cases. On the other hand, the increase in SW-GW mixing due to discharge events was larger in sand units, as well as in the generated heterogeneous cases in comparison to their equivalent homogeneous cases. The results also indicated that more intense discharge events (higher peak discharge) promoted SW-GW mixing more than longer events presenting similar cumulative discharge values. Our work extends the knowledge on SW-GW mixing, critical for river restoration strategies and for downstream management of dam-regulated rivers, and sheds some light on potential future research direction in integrated SW-GW assessments and modelling.

How to cite: Nogueira, G., Partington, D., and Fleckenstein, J. H.: Combined Effects of Geological Heterogeneity and Discharge Events on Groundwater and Surface Water Mixing, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-10343, https://doi.org/10.5194/egusphere-egu23-10343, 2023.

EGU23-10604 | ECS | Posters on site | HS2.2.5

Simulating tsunami flooding and seawater infiltration using coupled surface-subsurface flow models 

Jiaqi Liu, Philip Brunner, and Tomochika Tokunaga

Tsunami disasters cause not only human casualties and economic losses by short-term seawater flooding but also long-term salinization issues to groundwater resources due to seawater infiltration into coastal unconfined aquifers. The two processes, seawater flooding and infiltration, have been commonly simulated in a separate manner using tsunami models and groundwater models, respectively. Thanks to many recent advances in fully integrated hydrological modeling techniques, simulating surface and subsurface flow processes across various time scales within one conceptual framework is now feasible. Here, we present numerical simulations of the coupled processes of seawater flooding and infiltration based on a coastal urban area of Niijima Island, Japan, under the future Nankai Trough earthquake and tsunami scenarios. The HydroGeoSphere code was used to solve 2-D surface flow by St Venant equation and 3-D subsurface flow by Richard’s equation. The baseline simulation showed that road networks acted as fast paths for seawater flooding, while bare lands and building areas were the primary locations for seawater infiltration into the subsurface. The occurrence of seawater ponding was found to be controlled by both topographic variations at the land surface and the saturation condition of the soil medium in the subsurface. Moreover, the type of topographic data used in the model (DEM or DSM) and the equivalent hydraulic conductivity applied to building restructures showed significant effects on the simulated intensity of surface flow and the amount of seawater infiltration. These findings indicated that surface-subsurface interactions and the properties of both surface and subsurface domains are important factors to be considered for improving infrastructure safety evaluation and water resources management in tsunami-prone areas.

How to cite: Liu, J., Brunner, P., and Tokunaga, T.: Simulating tsunami flooding and seawater infiltration using coupled surface-subsurface flow models, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-10604, https://doi.org/10.5194/egusphere-egu23-10604, 2023.

EGU23-10678 | Orals | HS2.2.5

Numerical modelling of integrated processes in cryo-hydrogeological systems: Applications in Nunavik, Quebec, Canada 

John Molson, Oleksandra Pedchenko, Madiha Khadhraoui, Richard Fortier, and Jean-Michel Lemieux

Numerical simulations of coupled groundwater flow, heat and mass transport have been carried out for better understanding of cryo-hydrogeological system behavior under climate change.

Simulations are based on conceptual models of two well-monitored field sites at Umiujaq and Salluit, in Nunavik, (northern Quebec), Canada. The Umiujaq site contains discontinuous permafrost as discrete mounds within a marine silt bounded by unconfined and confined sand aquifers, while the Salluit site includes a bedrock river-talik system within continuous permafrost.

All simulations are run with the finite element HEATFLOW/SMOKER code which includes density-dependent groundwater flow, advective-conductive heat transport and advective-dispersive microparticle transport. Water-ice phase change, latent heat, ice-fraction dependent relative permeability and temperature-dependent thermal parameters are integrated in the solution. The thermal-hydraulic system is driven by ground surface recharge/discharge conditions which depend on the thermal state of the shallow subsurface (frozen or thawed), and by coupling with air-ground temperature gradients. Microparticle transport includes thaw-dependent particle suspension and velocity-dependent downgradient retention in heterogeneous porous media.

At the Umiujaq site, the two-dimensional vertical-plane simulations through a permafrost mound show how supra- and sub-permafrost groundwater flow can affect permafrost thaw which can lead to the release of microparticles, contributing to increased groundwater turbidity. At the Salluit site, supported by cross-sections of electrical resistivity tomography, the simulated 3D river-talik system follows the river meanders and responds dynamically to seasonal changes in air temperature and groundwater pumping.  The groundwater pumping rate needs to be managed for sustainable use, especially in winter when the talik is hydraulically disconnected from the river bed.

How to cite: Molson, J., Pedchenko, O., Khadhraoui, M., Fortier, R., and Lemieux, J.-M.: Numerical modelling of integrated processes in cryo-hydrogeological systems: Applications in Nunavik, Quebec, Canada, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-10678, https://doi.org/10.5194/egusphere-egu23-10678, 2023.

EGU23-11145 | ECS | Orals | HS2.2.5

Short-Term Dynamics of the Flowing Stream Drainage Density 

Izabela Bujak, Ilja van Meerveld, Andrea Rinaldo, and Jana von Freyberg

Many headwater streams are non-perennial. The flowing stream network dynamically expands and contracts during and after rainfall events, resulting in temporal changes in the flowing stream drainage density (DD). This dynamic behavior has consequences for solute transport and the organisms that live in the streams. Therefore, it is important to understand the hydrological processes responsible for these changes in DD to better predict the impacts of climate change on riverine ecosystems. However, until now, our knowledge of event-scale DD dynamics is limited because experimental data remain sparse.

We monitored DD in two 5-ha catchments in the Swiss Alpine foothills from June to October 2021. We installed a dense wireless sensor network to monitor the water levels in the streams and groundwater, soil moisture, and precipitation. In addition, we did multiple mapping surveys during different hydrological conditions and developed a simple model to calculate DD from these measurements at a 10-min resolution. We used these data to explore how short-term changes in DD relate to water storage in the catchments.

Our surveys showed that during the wet 2021 summer, DD varied considerably both in space and time, ranging from 2.7 to 32.2 and 7.8 to 14.6 km/km2 for the flatter and steeper catchment, respectively. The model provided reliable estimates of DD variations at 10-min resolution for both catchments (accuracies >0.94). In the flatter catchment, the relations between DD and either discharge or groundwater became steeper when DD was larger than 20 km/km2.DD increased rapidly with wetter conditions when the groundwater levels rose to 20 cm from the surface and streamflow was initiated in multiple shallow-incised channels. From analyzing multiple consecutive rainfall events, we found that the discharge-DD relationship was counterclockwise when conditions were dry. This is likely caused by the streamflow coming from nearby the outlet where the topographic wetness index is high. Surface flow in the upstream tributaries emerges only once the maximum subsurface transport capacity is exceeded, causing a rapid increase in DD. After the rainfall ends, discharge recedes quickly, whereas DD remains high due to ongoing groundwater seepage at the channel heads. For events with wetter conditions, there was no hysteresis, likely because the maximum subsurface transport capacity is exceeded faster throughout the catchment. Such threshold behavior and hysteresis were also not observed for the steep catchment, where multiple groundwater springs were flowing throughout the study period, resulting in much smaller DD variations.

How to cite: Bujak, I., van Meerveld, I., Rinaldo, A., and von Freyberg, J.: Short-Term Dynamics of the Flowing Stream Drainage Density, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-11145, https://doi.org/10.5194/egusphere-egu23-11145, 2023.

EGU23-11353 | ECS | Orals | HS2.2.5

Stable isotopes as a tool for improving rainfall-runoff modelling in South Africa 

Jared van Rooyen, Andrew Watson, Yuliya Vystavna, and Jodie Miller

Understanding the way in which a water budget is distributed within a hydrological system is imperative in the prediction of the systems behaviour when this water budget has changed. A complex interaction of variable flow rates, residence times and reactive transport, controls the available streamflow of a river system not only over seasonal changes, but under longer term climate fluctuations as well. Hydrological modelling techniques have been instrumental in predicting these changes by monitoring/simulating rainfall, river and groundwater contributions but are dependent on robust data collection through the maintenance of old infrastructure and the creation of new infrastructure. South Africa is a pertinent example of the decline of gauging infrastructure and a prime use case for novel stable isotope techniques as an accessory to traditional hydrological modelling in semi-gauged watersheds. Furthermore, to constrain contributions in modified systems, that include reservoirs and land use changes, isotopes present an opportunity to assess unpredictable water mobilisation in the streamflow system. In this study, stable isotope measurements of rainwater, groundwater and stream water (δ2H and δ18O), together with a tertiary mixing model were used to develop an isotope-enabled version of the JAMS/J2000 rainfall-runoff model, named J2000iso. The application was applied to the upper Berg River catchment, a catchment impacted by recent drought, but important for regional water supply. Compared to the base version, the J2000iso had 13% more simulated interflow, with 56% less variance in the ensemble results and less overall process uncertainty. The J2000iso was also more robust than the base version during a subsequent validation. The isotope-enabled models provided a means to constrain the proportion of surface runoff, interflow and baseflow considering the streamflow signal changes due to upstream reservoir operations. As many catchments in South Africa are still ungauged or impacted by upstream reservoirs, the J2000iso model provides a means to simulate hydrological processes, given the appropriate collection of isotope and auxiliary data.

How to cite: van Rooyen, J., Watson, A., Vystavna, Y., and Miller, J.: Stable isotopes as a tool for improving rainfall-runoff modelling in South Africa, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-11353, https://doi.org/10.5194/egusphere-egu23-11353, 2023.

EGU23-11410 | Orals | HS2.2.5

Soil moisture response as a tool to understand hydrological processes across forested catchments in different climates 

Daniele Penna, Catalina Segura, Marco Borga, Christophe Hissler, Jerome Latron, Pilar Llorens, Chiara Marchina, Nuria Martìnez-Carreras, and Giulia Zuecco

Comparative analysis of the hydrological response at the catchment scale across different climates is critical to understand possible similarities in runoff generation processes. In this work, we relied on high-resolution soil moisture measurements in three European forested catchments to characterize hydrological responses during different wetness conditions. The study sites include Ressi, Italy (2.4 ha), Weierbach, Luxembourg (42 ha), and Can Vila, Spain (56 ha). We analyzed the seasonal variability in the difference between soil moisture at a relatively shallow (10–15 cm) and deep (45–60 cm) location within soil profiles in each catchment in the period 2017–2021, which included a wide range of meteorological conditions. We found contrasting soil moisture patterns across the investigated catchments. In the most humid site, Ressi, which receives over 2000 mm of precipitation per year, we often found similar soil moisture at the two soil depths, and soil moisture at the shallow depth was rarely higher than that at the deeper layer, suggesting very frequent vertical connectivity in this site. In Weierbach, which receives around 1000 mm of precipitation per year, soil moisture in the shallow sensor was consistently higher than in the deeper soil except during wet conditions when water content was similar across the entire soil profile. During dry conditions, evaporation of shallow water resulted in consistently higher soil moisture in the deeper layers. We infer that in Weierbach vertical connectivity between deep and shallow soil layers develops only during wet conditions. Despite similar total precipitation amount between Can Vila and Weierbach, soil moisture patterns were very different. In Can Vila, soil moisture was consistently higher in the deeper layer compared to the shallow one irrespectively of the season. This difference could be driven by very high evaporation of shallow water or a significant contribution of groundwater that promotes vertical connectivity. Our approach provides a relatively simple and inexpensive method to assess differences in hydrological behavior solely based on soil moisture data, opening the possibility for further analysis and comparisons across multiple catchments.

How to cite: Penna, D., Segura, C., Borga, M., Hissler, C., Latron, J., Llorens, P., Marchina, C., Martìnez-Carreras, N., and Zuecco, G.: Soil moisture response as a tool to understand hydrological processes across forested catchments in different climates, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-11410, https://doi.org/10.5194/egusphere-egu23-11410, 2023.

EGU23-11474 | ECS | Orals | HS2.2.5

Improving drain flow simulations in a national hydrologic model with machine learning estimates of drain fraction 

Raphael Schneider, Saskia Noordujin, Hafsa Mahmood, Simon Stisen, and Anker Lajer Højberg

Agricultural areas are often artificially drained, especially in temperate and flat landscapes. This also applies to Denmark, where approximately half of the agricultural area is artificially drained, mostly with tile drains. The generated drain flow has significant impacts on various aspects of the hydrologic cycle such as groundwater recharge, flow paths and transport times. Consequently, drain flow is a major control on the transport of nutrients such as nitrogen. Yet, detailed knowledge of spatial and temporal variability of drain flow is inadequate due to insufficient observations of drain flow, lacking knowledge of drain infrastructure and issues of scale and hydrogeologic heterogeneity.

The objective was to improve the simulation of both the spatial and temporal variability of drain flow in a large-scale hydrological model used to map nitrate transport. This model is a physically-based, distributed groundwater-surface water model of all of Denmark. It is a major challenge to simulate drain flow distribution in space and time with the national model due to its coarse horizontal resolution (500m or 100m), and the lack of drain flow observations at relevant scale. Hence, to achieve the objective, we gathered existing field-scale drain flow observations from all over Denmark. For these drain catchments, fine-scale (10m) physically based hydrological models were setup and calibrated against the drain flow observations. After successful calibration, the resulting simulated distributions of drain fraction (drain flow relative to precipitation) were regionalized to applicable areas across all of Denmark. The regionalization was performed using decision tree machine learning algorithms, and a set of topographic and geologic covariates available nationally at fine resolution. An analysis of spatial transferability of the machine learning algorithm allowed to limit predictions to applicable areas. Finally, these estimates of drain fraction are used in the calibration of the large-scale national hydrologic model, amongst other objective functions such as streamflow and groundwater heads.

How to cite: Schneider, R., Noordujin, S., Mahmood, H., Stisen, S., and Højberg, A. L.: Improving drain flow simulations in a national hydrologic model with machine learning estimates of drain fraction, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-11474, https://doi.org/10.5194/egusphere-egu23-11474, 2023.

EGU23-12171 | ECS | Orals | HS2.2.5

When four or more (tracers) are better than one and why you should ski (to sample) 

Natalie Ceperley, Anthony Michelon, Harsh Beria, Joshua Larsen, Torsten Vennemann, and Bettina Schaefli

We measured a combination of natural tracers of water at a high frequency, including stable isotope compositions (δ2H, δ17O, δ18O), electrical conductivity, and water and soil temperature to characterize hydrological processes in a snow-dominated Alpine catchment and to understand the diversity of streamflow sources and flow paths. Previous work metabarcoding eDNA from stream samples led us to suppose that subsurface connectivity was a primary driver of genetic richness in the water of an alpine catchment, however our process understanding was limited.   By diving into temperature measurements in soil and water, electrical conductivity, and stable isotopes, we start to weave together the complexity of this subsurface connectivity.  Of particular interest in this alpine catchment is the seasonality of connectivity, which is mainly, in different forms, in melt periods occurring in spring and during rain-fed runoff events in summer and rain-on-snow events in winter.   This is dramatically different than in non-mountain, low-elevation environments where connectivity is observed in the cold or winter season.  In this presentation, we will compare and contrast what we learn from each tracer and highlight findings that could only be learned by bringing them all together.  We will reveal how these tracers inform our understanding of the timing of snow presence and melt, the existence of sub-snowpack local flow, the magnitude of subsurface exchange, and the mixing of snowmelt with groundwater. These insights into the details of streamflow generation in such a dynamic environment were only possible due to the intense, year-round field work.

How to cite: Ceperley, N., Michelon, A., Beria, H., Larsen, J., Vennemann, T., and Schaefli, B.: When four or more (tracers) are better than one and why you should ski (to sample), EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-12171, https://doi.org/10.5194/egusphere-egu23-12171, 2023.

EGU23-12302 | ECS | Orals | HS2.2.5

Monitoring of subsurface runoff using absolute gravimetry in Taiwan 

Kuanhung Chen and Cheinway Hwang

Calibration of subsurface runoff models in a catchment scale requires lots of observation sites/wells due to their scale difference. An observation site could fail to receive the required data due to variations in flow paths in rainfall events.  Therefore, establishing an effective monitoring site for subsurface runoff is a challenging task in hydrology studies. An alternative choice of monitoring equipment for subsurface runoff is using a terrestrial gravimeter. A terrestrial gravimeter has a broader sensible region than a monitoring well or several ERT (Electrical Resistivity Tomography) profiles. In addition, it takes the water(mass) itself as a tracer rather than using biogeochemical proxies and thus the quantity of runoff is estimated through observed gravity changes accordingly. Due to such advantages, in this presentation, we demonstrate the possibility of using gravimetry to monitor subsurface runoff in Taiwan. In one of the study sites at a proximal fan, our studies cover hourly, daily, weekly and monthly time spans, which encounter different intensities of rainfall over 1.5 years. The infiltration coefficient and percolation rate over 30 m length around our study site were determined in a severe rain event. In another study where we placed an absolute gravimeter in land subsidence regions, we estimated water storage changes at different sites after a wet season and rank their capability for being an artificial recharge pond. This presentation demonstrates the possibility of terrain gravimetry used in calibrating subsurface runoff models. We can picture that when quantum gravimeters are well-developed, high-temporal gravity measurements can assist to build a more accurate subsurface runoff model.

How to cite: Chen, K. and Hwang, C.: Monitoring of subsurface runoff using absolute gravimetry in Taiwan, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-12302, https://doi.org/10.5194/egusphere-egu23-12302, 2023.

EGU23-12690 | Posters on site | HS2.2.5

Drained, dampened, delayed: Deep soil moisture dynamics 

Theresa Blume, Daniel Rasche, Andreas Güntner, and Markus Morgner

Soil moisture is most often measured in-situ only to depths of about 50 cm. This is due to either the larger effort or challenges in installation or at some sites due to the presence of weathered bedrock. It is furthermore often assumed that with the top 50 cm of the soil we already capture the main part of the root zone and thus the major processes of infiltration, evaporation and transpiration should all be reflected in these soil moisture observations. However, due to lack of data we cannot be sure that this is really the case.

In this study we are reviewing soil moisture dynamics measured in the field at depths ranging between 70 and 450 cm. This includes more than 100 sensors at depth >70 cm and more than 60 at depth >100 cm. These sensors are installed in sandy soil in 14 different forest stands of the TERENO observatory in north-eastern Germany. We examine both seasonal and event responses. We furthermore compare the responses in the unsaturated zone also to the responses observed in shallow and deep groundwater. Using simple uncalibrated 1D Hydrus simulations we then put our observations into the context of those simulated by the model under pure matrix flow conditions, thus ignoring any preferential flow. The above described setup allows us to investigate the effects of infiltration, percolation, preferential flow, deep drainage, and transpiration at depths usually not accounted for in standard monitoring networks.

How to cite: Blume, T., Rasche, D., Güntner, A., and Morgner, M.: Drained, dampened, delayed: Deep soil moisture dynamics, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-12690, https://doi.org/10.5194/egusphere-egu23-12690, 2023.

EGU23-13461 | ECS | Posters on site | HS2.2.5

HydroCAL: An Integrated Surface-Subsurface Cellular Automata Hydrological Model to simulate streamflow and river network dynamics 

Luca Furnari, Alessio De Rango, Giuseppe Mendicino, Gianluca Botter, and Alfonso Senatore

One of the main constraints to the operational use of Integrated Surface and Subsurface Hydrologic Modelling (ISSHM) is the computational cost of such a complex approach. The growth of High-Performance Computing (HPC) has continuously pushed forward this limit, targeting the objective of "hyper-resolution" modelling. The Extended Cellular Automata (XCA) paradigm allows easy parallelization of numerical code and can be used in different HPC systems. Moreover, XCA have other unique features, like asynchronism, that can further break down the elapsed time.

HydroCAL is an integrated surface-subsurface Cellular Automata Layer hydrological model built by coupling a diffusive-like 2D water surface routing module and a 3D subsurface routing module based on the variably saturated Richards' equation. The model was implemented by adopting the parallel scientific software library Open Computing Abstraction Layer (OpenCAL), which allows researchers to exploit different parallelization techniques, hardware architectures and XCA-specific features.

Here we extend the HydroCAL model's capabilities, including groundwater and evapotranspiration modules that significantly contribute to the baseflow generation and river reach activation/deactivation dynamics, allowing continuous simulations beyond the storm-event scale. The enhanced model is used at ultra-high resolution (100 m) in a small steep-orography headwater Mediterranean catchment characterized by high hydrogeological heterogeneity. A multivariate calibration and validation approach is adopted over long-term simulations, using the observed active stream network dynamics and the recorded streamflow at the catchment outlet.

The results show that HydroCAL can adequately reproduce the hydrological response, simulating several multipeak events and reproducing the recession phases. Moreover, groundwater behaviour contributes to the simulation of the complex river network activation and deactivation dynamics. Overall, the HydroCAL model implementation upon the XCA paradigm allows highly detailed coupled simulations for long periods with reasonable computational times.

How to cite: Furnari, L., De Rango, A., Mendicino, G., Botter, G., and Senatore, A.: HydroCAL: An Integrated Surface-Subsurface Cellular Automata Hydrological Model to simulate streamflow and river network dynamics, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-13461, https://doi.org/10.5194/egusphere-egu23-13461, 2023.

EGU23-13578 | Posters on site | HS2.2.5

Evaluating surface-subsurface lateral flow interaction and solute concentration in a river channel using the diffusive wave inverse problem 

Roger Moussa, Samer Majdalani, Jean-Baptiste Charlier, and Martin Le Mesnil

Lateral flow L(t) representing surface-subsurface flow exchange is a major process during flood events, which can be either gains (positive) or losses (negative) to the channel. The inverse problem consists of evaluating L(t) knowing the inflow I(t) and the outflow O(t) on a channel. However L(t) and the corresponding solute concentration are very difficult to measure on real channels, and we are always not sure to which extent the evaluated L(t) is close to the real one. This paper aims at evaluating L(t) and the corresponding solute concentration in a channel using the analytical solution of the inverse problem of the Hayami diffusive wave equation (DWE) with L(t) uniformly distributed along the channel, used in the MHYDAS model (Moussa et al., 2002). Applications are shown on an experimental channel (4 m) and on six natural river channels (5 to 20 km). First, we conceived and built a novel 4 m experimental channel (Majdalani et al., 2019) where I(t), O(t) and L(t) and are highly controlled at 1 second time step and we realize 62 experimental hydrograph scenarios corresponding to different shapes of I(t) and L(t). We validate the hypotheses of both the DWE Hayami model and the corresponding inverse model (with very high criteria functions values for a large majority of scenarios) which reflects the ability of the DWE inverse model to reproduce complex lateral flow hydrograph and solute concentration dynamics (Moussa and Majdalani, 2018). Second, we apply the methodology on two French karst rivers in order to evaluate surface-subsurface flows during flood events (Le Mesnil et al., 2022): three river reaches in the Loue catchment in a temperate/mountainous climate, and three river reaches in the Cèze catchment in a Mediterranean climate. Results show that flood process seasonality is mainly related to karst aquifer saturation rate, while intra-site variability is linked to karst area extension and river morphology. Results are encouraging to extend this approach to a variety of sites, notably those affected by significant surface water-groundwater interaction and groundwater flooding. Such approach, by providing discretized information on flood processes, could help refining lumped hydrological models, or facilitate the use of semi-distributed ones. The coupled experimental-modelling approach proposed herein opens promising perspectives regarding the evaluation of lateral flow on real channels.

 

References

Le Mesnil M., Charlier J.-B., Moussa R., Caballero Y., 2022. Investigating flood processes in karst catchments by combining concentration-discharge relationship analysis and lateral flow simulation. Journal of Hydrology 605 (2022) 127358, 14 pp. https://doi.org/10.1016/j.jhydrol.2021.127358

Majdalani S., Moussa R., Chazarin J.-P., 2020. A novel platform to evaluate the dampening of water and solute transport in an experimental channel under unsteady flow conditions. Hydrological Processes, 34, 956-971. Article ID: hyp13624. DOI: 10.1002/hyp.13624

Moussa R., Majdalani S., 2019. Evaluating lateral flow in an experimental channel using the diffusive wave inverse problem. Advances in Water Resources, vol 127, 120–133. https://doi.org/10.1016/j.advwatres.2019.03.009

Moussa R., Voltz M., Andrieux P., 2002. Effects of the spatial organization of agricultural management on the hydrological behaviour of a farmed catchment during flood events. Hydrological Processes 16 : 393-412 (DOI: 10.1002/hyp.333).

How to cite: Moussa, R., Majdalani, S., Charlier, J.-B., and Le Mesnil, M.: Evaluating surface-subsurface lateral flow interaction and solute concentration in a river channel using the diffusive wave inverse problem, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-13578, https://doi.org/10.5194/egusphere-egu23-13578, 2023.

EGU23-13933 | ECS | Posters on site | HS2.2.5

Subsurface stormflow source area identification using depth profiles of the water-soluble organic matter 

Christina Fasching and Peter Chifflard

Hydrological dynamics of hillslopes, particularly subsurface stormflow (SSF), are highly complex and variable in space and time. Frequently, available studies are often limited to single slopes or few storm events. As a result, the transfer of these findings to other slopes or catchments is associated with great uncertainties. Thus, for upscaling and model validation, a quantification of the hydrological dynamics of hillslopes and the factors influencing the spatial and temporal patterns of subsurface stormflow is urgently needed. Closely related to the hydrological dynamics of hillslopes is the export of organic carbon from the soils to the adjacent stream. However, the spatial sources of carbon are still largely unclear because the exact flow paths of SSF within the slope are not well known. In order to address this knowledge gap, we took a hydro-biogeochemical approach, that measures the water-soluble organic matter (WSOM; concentration, absorbance and fluorescence) along 480 locations on 100 hillslopes, in four contrasting catchments – varying from low to high mountain ranges (Sauerland, Ore Mountains, Black Forest, Alps). This enables us to derive empirical relations among different landforms (i.e., convergent, divergent and planar slope shapes, flow path lengths and valley shapes), bedrock and soil properties, and to quantify the spatial variability and stability of subsurface hydrological process patterns (e.g., flow directions, transit times, hydrochemical and biochemical composition). Distributed sampling of WSOM along the soil profile (6 WSOM samples per profile; both during wet and dry conditions) will help to assess the vertical and lateral subsurface flowpaths of water in the unsaturated and saturated zone, and the spatial discretization of source areas for SSF. We will use an array of state-of-the-art laboratory equipment and methods (TOC-Analyzer, Fluorescence Spectrometry) to analyze WSOM. First results will show depth profiles of WSOM in the four contrasting catchments from the low to high mountain ranges (Sauerland, Ore Mountains, Black Forest, Alps). By these depth profiles source areas of SSF can be detected.

How to cite: Fasching, C. and Chifflard, P.: Subsurface stormflow source area identification using depth profiles of the water-soluble organic matter, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-13933, https://doi.org/10.5194/egusphere-egu23-13933, 2023.

EGU23-14388 | Posters on site | HS2.2.5

Fast and Invisible: Conquering Subsurface Stormflow through an Interdisciplinary Multi-Site Approach 

Peter Chifflard, Theresa Blume, Stefan Achleitner, Bernhard Kohl, Markus Weiler, Stefan Hergarten, Florian Leese, Luisa Hopp, Andreas Hartmann, Christian Reinhardt-Imjela, and Ilja van Meerveld

Where does water go when it rains? Where are floods generated and how? What controls stream water quality during events? These questions are important to many fields from engineering and flood protection to water and ecosystem management and prediction of impacts of global change. The most elusive processes in the process-ensemble underlying these questions is subsurface stormflow (SSF), the fast event response triggered by lateral subsurface flow. SSF is prevalent and a more important process than generally accounted for because a basic understanding based on systematic studies across scales and sites is still lacking. However, only with systematic studies will it be possible to really advance our understanding by discovering general principles of SSF functioning and to provide protocols and best practices for its assessment, both experimentally and with respect to modelling.

In many natural landscapes, SSF, i.e. any subsurface flow that occurs in response to a precipitation event, plays a major role in runoff generation: either by contributing directly to streamflow or by producing saturated areas or return flow, which then is the underlying cause of saturation excess overland flow. Therefore, much of what we see as event response in the hydrograph might be the direct or indirect result of SSF. It is likely that the discharge signal of SSF, including the indirectly triggered response in the stream, is larger than we generally assume. While its importance is probably largest in the headwaters, headwaters make up 70% of the stream network and greatly influence the supply and transport of water and solutes downstream. However, SSF is elusive and poorly accounted for as measurements are difficult for several reasons: the inaccessibility of the subsurface, the large spatial variability and heterogeneity, the variable sources and the fact that it is a threshold-driven process that only occurs during certain events. Thus, systematic studies of SSF are lacking, mainly due to difficulties of quantification.

We suggest such a systematic study of SSF in different environments, across scales, and using a well-designed and replicated selection of approaches including novel approaches. This will be followed by a systematic evaluation of methods and possible proxies as well as model intercomparison, evaluation and improvement. Thereby, we will focus on 4 challenges: 1) Development of novel experimental methods,2) Spatial patterns of SSF, 3) Thresholds and cascading effects of SSF, 4) Impacts of SSF.

Whereas standard single research projects investigate part of this puzzle at a specific location, this Research Unit provides the unique opportunity of fitting a large number of puzzle pieces together. This Research Unit will have a strong emphasis on experimental work in four contrasting catchments from the low to high mountain ranges (Sauerland, Ore Mountains, Black Forest, Alps) that then directly feeds into a collaborative modelling effort, which in turn influences experimental design in an iterative process.

How to cite: Chifflard, P., Blume, T., Achleitner, S., Kohl, B., Weiler, M., Hergarten, S., Leese, F., Hopp, L., Hartmann, A., Reinhardt-Imjela, C., and van Meerveld, I.: Fast and Invisible: Conquering Subsurface Stormflow through an Interdisciplinary Multi-Site Approach, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-14388, https://doi.org/10.5194/egusphere-egu23-14388, 2023.

Root-zone soil moisture is decisive in partitioning the water fluxes at the land surface, e.g. between evapotranspiration and groundwater recharge. Field-scale estimates of these time variant recharge rates can be derived from 1D soil hydrologic models, if the soil moisture product represents the respective scales and dynamics, and lateral fluxes can be neglected. Measured soil moisture time series can be used to calibrate these models by optimizing soil hydrologic properties (SHPs) and in this way increase confidence in simulated downward flux from a soil column (potential groundwater recharge). To obtain indirectly and non-invasively measure soil moisture at the field scale, Cosmic-ray neutron sensing (CRNS) has gained increasing attention in the last years. However, the variable penetration depth of the sensor and its decreasing sensitivity with depth and distance from the sensor complicate the interpretation of the soil moisture product and limit direct comparison to simulated soil moisture.

Within this study a two-layered Hydrus-1D model (up to 1.5 m depth) has been set up at an agricultural field site for one cropping season and calibrated using different soil moisture products to derive potential groundwater recharge estimates. While the use of point soil moisture sensor network data (SN) in the optimization is straightforward, different options to use CRNS data are evaluated: i) the COSMIC operator (simulates neutron count rates) ii) weighting simulated soil moisture according to CRNS vertical sensitivity, iii) applying a soil moisture profile correction on measured CRNS soil moisture before comparison.

Optimizing the SHPs did result in very good model performance for the SN as well as for the CRNS options (KGE > 0.86). While the SN delivers information down to a depth of 90 cm, using CRNS data that considers the vertical sensitivity (option i) and ii)) can result in difficulties informing the bottom layer of the model, which shows in optimized SHPs hitting the previously determined parameter bounds. Compared to that, using CRNS option (iii) leads to slightly reduced performance measures in the optimization but better informs the SHPs of the bottom layer when averaging modeled soil moisture over a fixed depth. For the successful optimizations, regardless of the method, recharge rates vary little and are comparable to independently estimated water flux at the field site.

Results of the study confirm the ability of the profile correction to increase CRNS information content to the main rooting zone and the validity of assuming a fixed integration depth, although this is expected to vary between field sites. This encourages also the use of CRNS soil moisture for non-experts of the method for soil hydrologic and landscape models as well as water balance calculations targeting downward fluxes.

How to cite: Scheiffele, L. M., Munz, M., Francke, T., Baroni, G., and Oswald, S. E.: Constraining groundwater recharge estimates at the field scale using soil hydrologic modelling and measured root zone soil moisture: how to deal with the vertical sensitivity of cosmic-ray measurements, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-15330, https://doi.org/10.5194/egusphere-egu23-15330, 2023.

Land subsidence is mainly caused by over-exploitation of groundwater, and it has been resulting in several problems along the coastal areas in Japan such as damages to buildings and facilities, changes of stream slopes, and increased risks of river flooding during high tides or storm surges. At the south bank of the Nabaki River in the Kujukuri coastal plain, Japan, some inland areas have become below the mean sea-level due to land subsidence. To prevent flooding in these areas, the local authority has constructed pumping stations and ditch networks at both sides of the tidal river since 1960s. The former can discharge the unnecessary water out to keep the land surface areas dry while the latter contributes to the agricultural productions by efficiently discharge water out. However, the pumping and discharging behaviours result in lowering groundwater levels that may cause further seawater intrusion. Here, a numerical model was developed by using the HydroGeoSphere code to investigate how the land subsidence and mitigating measures affect the quality of near-surface groundwater resources. The model solved coupled surface-subsurface flow and mass transport processes with the variable-density effect. Different scenarios were designed to compare the situations with and without land subsidence and pumping activities. The simulation results showed that, although the pumping stations and ditch systems performed effectively for preventing flooding associated with land subsidence, this system can enhance seawater intrusion to the inland aquifer from the tidal river. The results suggest that the pump stations and ditch systems built for preventing floods in subsidence areas should be carefully evaluated for their potential impacts on the groundwater flow regime and water quality. 

How to cite: Tsai, C. S., Liu, J., Ito, Y., and Tokunaga, T.: The impact of land subsidence and mitigating measures on near-surface groundwater salinities at the south bank of the Nabaki River, Japan, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-15520, https://doi.org/10.5194/egusphere-egu23-15520, 2023.

EGU23-15840 | ECS | Posters on site | HS2.2.5

Development of a ground platform to measure runoff data in rivers in the brazilian semiarid region 

Rodrigo Rodrigues and Carlos Costa

The occurrence of floods dates back to the history of human civilization, and in recent years it has been increasing significantly. To minimize the risks and mitigate the damage caused by extreme events, an efficient warning system must exist. In Brazil, river discharge data are produced by means of fluviometric stations maintained by government agencies. A promising solution is the application of tools that employ image-based approaches, where it is possible to determine the surface velocity of the riverbed from a particle image velocimetry (VIP) analysis. To correct the topography of the riverbed, LIDAR sensors and structure-of-motion photogrammetry (EDM) techniques can be employed in association with the tool applied to determine surface velocity fluxes. After the generation of raw runoff data there will be a calibration and treatment of the obtained data. In this context, the objective of the project is to develop ground platforms capable of performing real-time estimates of river discharge. It is expected that after the development of the data collection platform it will be possible to apply the tool in the areas of sedimentology, hydrology, water quality simulation, urban macrodrainage, power generation, among others. 

How to cite: Rodrigues, R. and Costa, C.: Development of a ground platform to measure runoff data in rivers in the brazilian semiarid region, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-15840, https://doi.org/10.5194/egusphere-egu23-15840, 2023.

Local heavy precipitation regularly causes great damage resulting from flash floods in smaller catchments. Appropriate discharge records are usually unavailable to derive an extreme value statistics and regionalization approaches predicting peak discharge from discharge records of larger basins cannot include the small-scale effects and local processes. In addition, forecasting flash floods from rainfall forecast requires to identify the initial soil moisture conditions under which a catchment is most prone to trigger flash floods. In this respect, soil moisture affects runoff at the local scale during runoff generation (infiltration), but also at the catchment scale during runoff concentration with possible infiltration of overland flow (run-on infiltration) along the flow path.

Our proposed framework to study the role of soil moisture on flash floods includes three steps: (1) to validate long-term hydrological simulations with in-situ soil moisture data to derive typical probability distributions of initial soil moisture depending on soil properties, vegetation and land cover, groundwater influences, etc; (2) to derive the sensitivity of runoff generation to soil moisture at the local and catchment scale by combining different probabilities for rainfall amount, duration and initial soil moisture resulting in the same joint probability and (3) to include the effect of soil moisture on run-on infiltration by linking a distributed hydrological and 2D-hydraulic model to simulate runoff hydrographs with and without run-on infiltration. The final set of simulations with the distributed, process-based rainfall-runoff model RoGeR for different temporal (event to long-term) and spatial scale (plots to submeter scale) allows us for a given catchment to derive the role of soil moisture on different hydrological processes (runoff generation and runoff concentration). We developed a spatial explicit method, which combines the joint probability of soil moisture and rainfall for runoff formation with hydraulic assumptions to determine runoff concentration and thus the corresponding hydrographs and the specific conditions in a catchment that can trigger flash floods. These simulations are compared in different test catchments with discharge records to validate out model chain. Finally, a comparison among different catchments with different characteristics (soil, geology, land-use, geomorphology, etc) enables us to derive a flood generation soil moisture sensitivity which should help to improve hydrological models to include all relevant processes and to focus our future in-situ soil moisture observations in the sensitive catchments to allow for a better prediction of flash floods by including observed soil moisture instead of simulated values. 

How to cite: Weiler, M., Leistert, H., Schmit, M., and Steinbrich, A.: Linking in-situ and simulated soil moisture data for flood prediction: the advantage of joint probabilities of initial soil moisture and rainfall characteristic, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-16866, https://doi.org/10.5194/egusphere-egu23-16866, 2023.

EGU23-17088 | Orals | HS2.2.5

Modeling the age of subsurface runoff at the catchment scale – what makes it younger or older? 

Ingo Heidbüchel, Jie Yang, and Jan H. Fleckenstein

Whether subsurface flow is relatively young or old when it passes by the catchment outlet is a strong indicator of weathering processes, nutrient availability, pollution susceptibility and the hydrologic response of a catchment. It depends not only on individual catchment, climate, event and vegetation properties, it is also the result of a multitude of interactions between different processes and catchment states within the hydrologic system.

In order to begin to disentangle the cause-effect chains (or better even: webs), we employed the physically-based, spatially explicit 3D model HydroGeoSphere in a virtual catchment running 100 scenarios with different combinations of catchment, climate and vegetation properties. One result showed, e.g., that streamflow in forested areas appeared to become older on average compared to a non-vegetated site. Upon closer inspection, this was not necessarily only caused by subsurface runoff becoming slower/older due to lower hydraulic conductivities of drier soils when there was active root water uptake. Another component of this increase in stream water age was the different partitioning of precipitation into subsurface runoff and groundwater flow. Relatively more water was transported in the slower groundwater domain and less within the soil at the bedrock-soil interface.

This is to show that, in order to make meaningful predictions about the age of hydrologic fluxes, it may not be the best approach to single out specific catchment and climate properties. Instead, it can be extremely helpful to look at the individual properties and the processes they control, their potential interactions and interdependencies, in a bottom-up approach within the framework of a hydrologic model.

How to cite: Heidbüchel, I., Yang, J., and Fleckenstein, J. H.: Modeling the age of subsurface runoff at the catchment scale – what makes it younger or older?, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-17088, https://doi.org/10.5194/egusphere-egu23-17088, 2023.

EGU23-17547 | ECS | Posters on site | HS2.2.5

Optimization of Soil Texture and Hydraulic Parameters Using the Soil Moisture Observation in Land Surface Model 

Sujeong Lim, Claudio Cassardo, and Seon Ki Park

Soil moisture is a key variable in the hydrologic cycle and affecting to weather and climate, thus accurate soil moisture prediction is necessary in the land surface modeling. In this study, we use UTOPIA (University of Torino land surface Process model for Interaction in the Atmosphere) that is a one-dimensional land surface model representing the interactions at the interface between atmospheric surface, vegetation and soil layers. Soil texture estimated by percentages of clay, silt, and sand is the dominant factor to predict soil moisture. However, it is hard to measure the accurate soil information due to insufficient and uncertain observation. Therefore, we have implemented the micro-genetic algorithm (micro-GA) within UTOPIA to optimize the percentages of clay, silt, and sand estimating the soil texture and hydraulic parameters by evaluating the soil moisture performance against in-situ observation. As a global optimization algorithm, the micro-GA evolves to the best potential solution based on the natural selection or survival of the fittest. Compared to the control experiments using a soil database or in situ observation, optimization results show that the optimal soil texture and hydraulic parameters lead to an improvement in soil moisture prediction.

How to cite: Lim, S., Cassardo, C., and Park, S. K.: Optimization of Soil Texture and Hydraulic Parameters Using the Soil Moisture Observation in Land Surface Model, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-17547, https://doi.org/10.5194/egusphere-egu23-17547, 2023.

EGU23-317 | ECS | Orals | HS2.2.7

Testing drought sensitivity of different land use types via a low parameter isotope-aided ecohydrological model approach in a lowland headwater catchment, Germany 

Jessica Landgraf, Dörthe Tetzlaff, Christian Birkel, Jamie Lee Stevenson, and Chris Soulsby

Stable water isotopes are naturally occurring conservative tracers that act as a fingerprint of water sources and ecohydrological fluxes. Previous studies have shown that some of those fluxes, like evapotranspiration and infiltration, are influenced by vegetation. Thus, land use will play an increasingly important role in water partitioning considering projected climate change-induced shifts of patterns in precipitation and increased atmospheric water demand. The sensitivity of different land use types to drought conditions and their influence on water partitioning varies, and still lacks understanding.

We used stable water isotopes to follow the pathway of precipitation into soil at a lowland headwater catchment with multiple land use types (forest, grassland, arable and agroforestry sites) and integrated our data into a one-dimensional, tracer-aided, plot scale model. The model requires precipitation, potential evapotranspiration and leaf area index as input data and the results were calibrated to real time soil moisture and isotope data. The dataset was collected in the long-term experimental Demnitzer Millcreek Catchment (DMC), Germany, over the growing season of 2021 and includes hydroclimatic conditions as well as isotopes in precipitation, soil water and groundwater. The 2021 conditions, though relatively average in terms of wetness, were affected by a dry spring, an exceptionally large summer storm event (~60 mm) as well as “memory effect” of previous intense drought years.

The implementation of the isotope calculations into the model showed that such a simple, low-parameterisation approach with easily accessible input data can be used to estimate the water balance and track isotopic transformations under plot sites with various land use conditions. The most rapid turnover of water was found under arable land use which resulted in short-term crop vulnerability to drought and slow but more rapid recovery and replenishment of moisture deficits. Forest soils showed slower water turnover with lower soil moisture, mainly reflecting higher interception losses and higher transpiration rates. This, together with access to deeper water, means drought stresses build more slowly at forest sites but can last much longer as storage recovery is slow (>1 year) due to high evapotranspiration. Via adapting the model input data, we further simulated drought conditions to assess the “water footprint” of alternative land use under drought stress.

Our study illustrated the potential of stable water isotope data for simplified ecohydrological modelling approaches to quantify water partitioning. The different effects of land use types on ecohydrological fluxes were successfully simulated and their drought resilience was estimated. For the DMC and similar lowland catchments with similar soil types (sand at forest, loam at grassland and crops) and land cover in Central Europe with the modelled drought conditions, forest sites will initially be more resilient but more vulnerable to lasting droughts, while grassland and arable sites tend to recover more quickly, but can be rapidly stressed by short-term severe events. The modelling provides an experimental framework for assessing the differential effects of droughts of varying longevity and severity on alternative land use strategies.

How to cite: Landgraf, J., Tetzlaff, D., Birkel, C., Stevenson, J. L., and Soulsby, C.: Testing drought sensitivity of different land use types via a low parameter isotope-aided ecohydrological model approach in a lowland headwater catchment, Germany, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-317, https://doi.org/10.5194/egusphere-egu23-317, 2023.

EGU23-374 | ECS | Orals | HS2.2.7

Synoptic water isotope surveys to understand the hydrology of large intensively managed catchments 

Ke Chen, Doerthe Tetzlaff, Guodong Liu, Chris Soulsby, and Tobias Goldhammer

Precise knowledge of hydrological processes across large scale catchments is crucial to sustainably meet the growing water demand and improve water management strategies in cities. However, it has been always a major challenge to comprehensively understand the hydrology of a large catchment due to the spatial heterogeneity of climate, topography and anthropogenic activities. Combining tracers with hydroclimatic records, this study used seasonal synoptic surveys in 2021 to better understand the water cycling, storage and losses of the intensively managed 10,000 km2 catchment of the River Spree in Berlin, Germany. Apart from the upper headwaters, the hydrology of the Spree is heavily regulated by reservoir releases, pumped minewater discharges, engineered flows in wetlands and lakes, water abstractions and urban drainage. Moreover, the catchment is drought-sensitive with potential evapotranspiration often exceeding annual rainfall. This is reflected in the spatial and temporal variability of the isotopic composition of river water. In the steeper, upper headwater areas, the river is dominated by groundwater sources but showing evident influence by rainfall in winter, with a “flashy” rainfall-runoff response. However, flows in the middle part of the catchment have enhanced baseflows and attenuated high flows from extensive reservoir and pumped minewater releases. The reservoir waters are isotopically heavier and reflect the effects of open water evaporation. Fractionation effects strengthen downstream as managed wetland areas and natural lakes further enhance evaporation and attenuate flows. Our estimations on evaporation losses also show that the mine water pumping, water abstractions and wastewater additions largely contribute to the catchment water balance and therefore have pronounced impacts on water evaporations. Seasonally, the effects of evaporation on the isotopic composition of the lower river network are strongest in summer and autumn, though they remain in winter and spring, indicating a large memory effect due to long mean travel times within the river system. Tritium variability along the river reflects inputs of younger and older water in different parts of the river system; though the influence of pumped groundwater means that the mean age of stream water in the lower river is likely to be >50 years. Isotope studies at large scales play a valuable role to in better understanding the hydrology of this complex, heavily modified river system and provide an evidence base for more sustainable management of the potentially fragile water resource situation in the future.

How to cite: Chen, K., Tetzlaff, D., Liu, G., Soulsby, C., and Goldhammer, T.: Synoptic water isotope surveys to understand the hydrology of large intensively managed catchments, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-374, https://doi.org/10.5194/egusphere-egu23-374, 2023.

Understanding the transport processes and travel times of pollutants such as nitrate or pesticides in the subsurface is crucial for an effective management of drinking water resources. Transport processes and hydrologic processes, like infiltration, percolation, root water uptake or runoff generation processes, are inherently linked to each other. In order to account for this link, we couple the process-based hydrologic model RoGeR (including infiltration in the soil matrix, macropores and cracks) with StorAge Selection (SAS) functions. We assign to each hydrological process a specific SAS function (e.g. beta-type distribution or power distribution). To represent different transport mechanisms, we combined a specific set of SAS functions into four transport model structures: complete-mixing, piston flow, advection-dispersion and advection-dispersion with time-variant parameters. In this contribution, we quantify and illustrate the results of our modelling experiments at the Rietholzbach lysimeter, Switzerland. We compare our simulations to the measured hydrologic variables (percolation and evapotranspiration fluxes and soil water storage dynamics) and the measured water stable isotope signal (18O) in the lysimeter seepage for a period of ten years (1997-2007). An additional artificial bromide tracer experiment was used to benchmark the models. Additionally, we carried out a sensitivity analysis and provide Sobol’ indices. Our results show that the advection-dispersion transport model with time-variant parameters produces the best results. And thus, advective-dispersive transport processes play a dominant role at Rietholzbach lysimeter. Our modelling approach provides the capability to test hypotheses of different transport mechanisms and to improve process understanding and predictions of transport processes. Overall, the combined model allows a very effective simulation of combined flux and transport processes at various temporal and spatial scales.

How to cite: Schwemmle, R. and Weiler, M.: Consistent modelling of transport processes and travel times – coupling hydrologic processes with StorAge Selection functions, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-457, https://doi.org/10.5194/egusphere-egu23-457, 2023.

The northeastern states of India have extensive deposits of coal among other minerals. Coal mining activities contribute significantly to the economy of these states, providing livelihood to a substantial segment of the populace. Unscientific mining practices have contributed adversely to environmental health of the region, particularly to aquatic systems. Acid mine drainage (AMD) discharge from the mines pollute the streams and rivers, causing serious deterioration of the aquatic environment. Stable isotopes combined with physico-chemical parameters are a promising tool for understanding pollution sources, hydrological processes, factors influencing such processes, and fate of pollutants in hydrological systems. The present study was conducted in AMD affected streams & rivers flowing through the states of Arunachal Pradesh, Nagaland, Assam and Meghalaya in northeast India in two different seasons (pre-monsoon (PRM) & post monsoon (POM)). Water samples were analyzed for 24 physicochemical parameters including the major ions. Stable isotopes of oxygen & hydrogen in water samples were estimated. The results of both sampling seasons are significantly different and reveal that water samples of all sampling sites are dominated by presence of high SO42- in both the sampling seasons; abundance of major ions during PRM are in order SO42->Mg2+>Ca2+>HCO3->Na+>Cl->NO3->K+>NH4+>F- and during POM are in order SO42-> Ca2+>Mg2+>HCO3->Na+>Cl->NO3->K+>NH4+>F-. The stable isotopes of water (δ18O & δD) analysis results indicated enrichment during the POM sampling season. δ18O (‰ V-SMOW)  ranged between -8.60 to -4.95 during PRM and -6.60 to -3.94 during POM, δD (‰ V-SMOW) ranged between -58.29 to -29.63 during PRM and -41.40 to -28.69 during POM. The deuterium excess (d-excess ‰) ranged between 5.70 ~ 17.94 during PRM and 1.57 ~ 14.49 during POM. The hydrochemical characteristics of water during both sampling seasons were deciphered through comprehensive analysis of hydrochemistry (piper diagram, durov plot, gibbs diagram, ion ratios, chadha’s plot) and stable isotopes. The results are discussed.

How to cite: Kumar, V., Paul, D., and Kumar, S.: Seasonal Variation in Stable Isotopes and Physico-chemical Characteristics of AMD Affected Water Bodies in Northeast India, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-859, https://doi.org/10.5194/egusphere-egu23-859, 2023.

EGU23-1230 | ECS | Orals | HS2.2.7

What explains low young water fractions at high elevations? 

Alessio Gentile, Davide Canone, Natalie Ceperley, Davide Gisolo, Maurizio Previati, Giulia Zuecco, Bettina Schaefli, and Stefano Ferraris

The concept of young water fraction, introduced by Kirchner (2016) and defined as the fraction of streamflow that was stored less than about 2-3 months in the catchment, is increasingly used in catchment intercomparisons studies to understand and conceptualize the hydrological processes governing the catchment's functioning. However, the development of perceptual models is not always as straightforward as it may seem. Past works have shown that high mountainous catchments worldwide reveal small young water fractions. These low young water fractions at high elevations have been explained by different hydrological processes, including deeper vertical infiltration promoted by the presence of both fractured bedrock and freely draining soils (e.g., luvisols and cambisols) and long groundwater flow paths driven by the topographic roughness. But, a harmonious explanation of how the relevant mechanisms in mountainous catchments lead to low young water fractions at high elevations is missing.

Using a data set composed of 27 study catchments, located both in Switzerland and in Italy (of which 22 are from the previous work of von Freyberg et al., 2018), we explore both the drivers and the conceptualization of the processes that potentially clarify this surprising result. We assume that this lowering can be explained by groundwater storage potential and the interplay of the seasonal dominance of hydrological processes. For groundwater storage potential we use the proportion of catchment area covered by Quaternary deposits (a parameter that is readily available for the studied catchments). For the interplay of seasonal processes, we use the length of the low-flow period as a measure for the duration of the groundwater (in terms of age, old water) dominated recession period.

Our results suggest that the length of the low-flow period is clearly the main driver of low young water fractions at high elevation. Here, the long winter period, characterised by absence of liquid water input and hence by a low-flow regime, promotes a progressive emptying of the groundwater storage. Even during summer, recent snowmelt and rainfall that transit through the subsurface push out old groundwater into the stream, as reflected by high proportions of baseflow also during high-flow periods. However, during summer, the relative share of old water remains lower than during winter and accordingly, the longer the winter period (with very low young water fractions), the lower the annual young water fraction. Quaternary deposits could play a role in reducing young water fractions via their capacity to store groundwater, but further detailed geological information would be necessary for a complete picture about the role of geology.

How to cite: Gentile, A., Canone, D., Ceperley, N., Gisolo, D., Previati, M., Zuecco, G., Schaefli, B., and Ferraris, S.: What explains low young water fractions at high elevations?, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-1230, https://doi.org/10.5194/egusphere-egu23-1230, 2023.

EGU23-1503 | ECS | Orals | HS2.2.7

Water quality and water circulation formation of a deep lake on the basis of interaction between surface water and groundwater in a highly acidic hot spring region 

Koichi Sakakibara, Sae Mizushima, Yoshikuni Hodoki, Maki Tsujimura, Kei Suzuki, and Hodong Park

Hydrological interactions between surface water and groundwater are key processes to describe the watershed water cycle including lake water hydrology. Understanding these processes is important for quality and quantity controls of water resources and their future management. Water originating from mining/hot spring regions gives significant impacts on local water resources. However, hydrological processes of how the discharged water with unique water quality affects different water bodies have not been fully understood. Therefore, the study aims to investigate features of surface water and groundwater interaction forming lake hydrology in a highly acidic Tamagawa hot spring region, in Japan. For this, the river water, spring water, and lake water at 51 locations in total were sampled. Lake water collection with depths of 0, 50, 100, 200, 300, and 400 m was undertaken at the center of Lake Tazawa. A variety of environmental tracers such as pH, EC, DO, inorganic ion concentrations, oxygen/hydrogen stable isotopes, CFCs, and SF6 in collected water samples were measured.

The river water upstream of the Tamagawa River showed a pH of <3.0 and characteristic Ca-Cl type water quality due to the influence of a highly acidic hot spring. The other river and spring waters were almost neutral and of the Na-HCO3 type water quality. Lake Tazawa water was weakly acidic (pH 5.5, Ca-Cl type water quality), suggesting that the water in the lake originated mainly from the Tamagawa River. Vertical profiles of environmental tracers of lake water at the center of Lake Tazawa indicated that dissolved oxygen concentrations were above 87% saturation even at depths greater than 100 m, suggesting that a rapid lake circulation was occurring. The multiple uses of gas tracers (SF6 and CFC-12) suggested that water age is 4 and 12-20 years in the water close to the lake surface and water deeper than 50 m, respectively. The binary plot of SF6 and CFC-12 concentration indicated that the exponential mixing primarily governs lake water circulation processes. Moreover, calculations of the water balance of Lake Tazawa for the five-year period from 2011 to 2015 inferred that groundwater inflow into Lake Tazawa from the surrounding area may have occurred at a rate of at least 5-12 mm/day. These findings suggest that the inflow of groundwater and river water into Lake Tazawa is responsible for the lake's water quality and a part of rapid lake water circulation.

How to cite: Sakakibara, K., Mizushima, S., Hodoki, Y., Tsujimura, M., Suzuki, K., and Park, H.: Water quality and water circulation formation of a deep lake on the basis of interaction between surface water and groundwater in a highly acidic hot spring region, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-1503, https://doi.org/10.5194/egusphere-egu23-1503, 2023.

EGU23-1537 | Posters on site | HS2.2.7

The tale of two tracers: No evidence for systematic underestimation of transit times inferred by stable isotopes in SAS function models. 

Markus Hrachowitz, Siyuan Wang, Gerrit Schoups, and Christine Stumpp

Stable isotopes (δ18O) and tritium (3H) are frequently used as tracers in environmental sciences to estimate age distributions of water. However, it has previously been argued that seasonally variable tracers, such as δ18O, generally and systematically fail to detect the tails of water age distributions and therefore substantially underestimate water ages as compared to radioactive tracers, such as 3H. In this study for the Neckar river basin in central Europe and based on a >20-year record of hydrological, δ18O and 3H data, we systematically scrutinized the above postulate. This was done by comparing water age distributions inferred from δ18O and 3H with a total of 12 different model implementations, including lumped parameter sine-wave (SW) and convolution integral models (CO) as well as integrated hydrological models in combination with SAS-functions (IM-SAS).

We found that, indeed, water ages inferred from δ18O with commonly used SW and CO models are with mean transit times (MTT) ~ 1 – 2 years substantially lower than those obtained from 3H with the same models, reaching MTTs ~ 10 years. In contrast, several implementations of IM-SAS models did not only allow simultaneous representations of stream flow as well as δ18O and 3H stream signals, but water ages inferred from δ18O with these models were with MTTs ~ 16 years much higher than those from SW and CO models and similar to those inferred from 3H, which suggested MTTs ~ 15 years. Characterized by similar parameter posterior distributions, in particular for parameters that control water age, IM-SAS model implementations individually constrained with δ18O or 3H observations, exhibited only limited differences in the magnitudes of water ages in different parts of the models as well as in the temporal variability of TTDs in response to changing wetness conditions. This suggests that both tracers lead to comparable descriptions of how water is routed through the system. These findings provide evidence that allowed us to reject the hypothesis that δ18O as a tracer generally and systematically “cannot see water older than about 4 years” and that it truncates the corresponding tails in water age distributions, leading to underestimations of water ages. Instead, our results provide evidence for a broad equivalence of δ18O and 3H as age tracers for systems characterized by MTTs of at least 15 – 20 years.

Overall, this study demonstrates that previously reported underestimations of water ages are most likely not a result of the use of δ18O or other seasonally variable tracers per se. Rather, these underestimations can be largely attributed to choices of model approaches and complexity not considering hydrological next to tracer aspects. We therefore advocate to avoid the use of this model type in combination with seasonally variable tracers if possible, and to instead adopt SAS-based or comparable model formulations.

How to cite: Hrachowitz, M., Wang, S., Schoups, G., and Stumpp, C.: The tale of two tracers: No evidence for systematic underestimation of transit times inferred by stable isotopes in SAS function models., EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-1537, https://doi.org/10.5194/egusphere-egu23-1537, 2023.

Understanding the hydrogeological functioning of aquifers is essential in contexts where water resources are intensively used. Moreover, climate change can have long-term effects on groundwater in terms of availability, residence and transit times. Thus, careful management of groundwater resources require the understanding of the aquifer’s characteristics that can allow then the setting of sustainable yields values in contexts where water is exploited. This understanding requires in particular the estimation of the age of the groundwaters as well as the transfers/transit times within the aquifers. Our study focuses on the Volvic volcanic aquifer (Chaîne des Puys, France), where the question of water use has increasingly raised for several years, given the significant use of drinking water, both for the public drinking water network and bottled water, and the decrease of precipitations (and groundwater recharge) over the watershed due to climate change.

Previous studies on Volvic watershed allow defining the overall functioning of the system and comparing withdrawals and recharge on an annual scale, but groundwater ages have been only roughly defined even if they appear as a key point for addressing the question of the resource decrease. We propose then a multi-tracers approach, based on hydrogeological monitoring (hydrodynamical and meteorological data’s), including the estimation of groundwater ages (CFCs, tritium (3H)), major and traces elements chemistry and water stable isotopes (18O/2H) to better characterise this resource decrease and more peculiarly its origin and its impact on the environment that has never been addressed.  The relative fractions of modern and ancient water contributions to the Volvic aquifer will thus be estimated as well as the apparent ages of groundwaters. We highlight here the complementarity of tracers used in the dating of waters, which allows a better definition of recharge sources and flow paths within the aquifer.

This will provide key information about the time of the recharge and the time when the decrease began due to increase of abstraction, climate change or a combination of both of these effects.

How to cite: Nevers, P., Aumar, C., Celle, H., Vergnaud, V., Yvard, B., Huneau, F., and Mailhot, G.: Estimation of groundwater ages, recharge and transfers times in volcanic aquifers: Advantages and interests of multi-tracer approaches (3H, CFC-SF6, 18O/2H) coupled to hydrogeological data in the management of water resource of the Volvic watershed (FR)., EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-1880, https://doi.org/10.5194/egusphere-egu23-1880, 2023.

As global climate change alters hydroclimatic responses beyond the range of predictability based on historic hydrometeorological records, water resource practitioners are increasingly reliant on new methods of modelling continental and global hydrology. Though local scale heterogeneity and connectivity between hydrologic storages and fluxes tends to be averaged out across large domains, it is precisely these process scale changes that remain crucial as early indicators of climate change. A lack of data at continental scales, and particularly in high latitude regions, can therefore challenge accurate model calibration and evaluation. Efficient and accessible hydrologic prediction tools capable of diagnosing and interpreting continental scale changes in water balance components and overall water supply, ecosystem changes, and uncertainty methods for operational decision-making are needed.

This presentation focuses on the recent advances in large-domain tracer-aided stable isotope modelling and the contributions isotope tracers make on improving hydrologic process representation across large-domains. The influence of process-based model outcomes will be highlighted using examples from cold regions domains, including the propagation of small historical differences into significantly different upper quantile flow predictions. Despite significant advances in tracer-aided modelling, the path forward must include building and supporting global operational monitoring networks, providing standard guidance for integration of tracer-aided approaches, and a focus on building model agnostic workflows and tools that efficiently leverage tracer-aided approaches.

How to cite: Stadnyk, T.: Predicting the unpredictable: Advances in Tracer-aided hydrologic modeling, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-2158, https://doi.org/10.5194/egusphere-egu23-2158, 2023.

EGU23-2231 | Orals | HS2.2.7

How to deal with spectral interferences when measuring water stable isotopes of plants? 

Natalie Orlowski, Lena Wengeler, and Barbara Herbstritt

Nowadays, a wide range of water extraction/vapor equilibration techniques for obtaining soil and plant water isotopic composition (δ18O and δ2H) is applied by various ecohydrological disciplines. Here, researchers need to rely on accurate and precise measurements of water isotope ratios for tracing water movement through the critical zone. Previous research has shown that utilizing isotope ratio infrared spectroscopy (IRIS) to analyze water or vapor samples containing co-extracted/-equilibrated organic contaminants (e.g., methanol, ethanol) has the potential to result in significant inaccuracies through spectral interferences. However, the scientific community and the manufacturers have not effectively addressed the inaccuracies caused by organic contaminants. While some hardware solutions for combusting organics as well as some software solutions exist for spectral interference detection during liquid water IRIS analysis, limited tools exist for the post-correction of direct vapor-mode IRIS data e.g., from in-situ water vapor measurements or from the direct water vapor equilibration laser spectrometry method (DVE-LS).

For our study, we applied three different water extraction and vapor equilibration techniques (i.e., DVE-LS, in-situ water vapor measurements and cryogenic vacuum extraction) to four types of vegetables (cauliflower, celery root, kohlrabi and potatoes). We investigated how co-extracted organic contaminants (i.e., methanol and ethanol) via the different methods affect the isotopic ratios between liquid and vapor CRDS measurements of our vegetable samples. Through applying different CRDS instrument-specific post-correction options, we could reduce isotopic discrepancies and maximize the accuracy and precision of CRDS measurements from vegetables.

We could show that all vegetables produced species-specific different amounts of organic contaminants, which affected the isotope ratios obtained via the different extraction or vapor equilibration techniques in different ways. Clear relationships between DVE-LS samples and spectral parameters indicated co-equilibrated contaminants which we used for a technique-specific ‘organics-correction’. Whereas, results obtained from in-situ water vapor measurements were the least affected by organic contaminants and showed the smallest data spread. Those were also comparable to results from cryogenic vacuum extraction for some type of vegetables.

Our study underlines the importance and necessity of plant water vapor isotope data post-correction and highlights the need for a definitive and general protocol in order to prevent ill-founded ecohydrological data interpretations.

How to cite: Orlowski, N., Wengeler, L., and Herbstritt, B.: How to deal with spectral interferences when measuring water stable isotopes of plants?, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-2231, https://doi.org/10.5194/egusphere-egu23-2231, 2023.

    River damming alters biogeochemical cycles in river continuum. Yet, its effect on the biogeochemical behavior of riverine strontium (Sr) is still unclear. Here, we measured riverine 87Sr/86Sr in both dissolved and particulate phases and relevant parameters in karst cascade reservoirs of Southwest China, and simulated 87Sr/86Sr fractionation during biological processes through experimental incubation of model phytoplankton. The results showed that the dissolved 87Sr/86Sr was rather homogeneous across the water body and nearly identical to inorganic particulate-bound 87Sr/86Sr, and reservoir Sr mainly sourced from carbonate weathering. However, the dissolved Sr concentrations were stratified and increased with depths of the reservoir water columns. This stratification was likely caused by phytoplankton and the precipitation and dissolution of calcite, with the stratified strength controlled by reservoir hydraulic loads. A long-term loads along cascade reservoirs thus could result in a significant increase in dissolved Sr concentrations rather than 87Sr/86Sr. The culture experiment indicated that the dissolved Sr was massively captured by the phytoplankton during which insignificant 87Sr/86Sr fractionation occurred. Thus, the 87Sr/86Sr of reservoir phytoplankton would conserve the dissolved 87Sr/86Sr. The distinctly lower 87Sr/86Sr of phytoplankton than terrestrial organic particulates highlights its potential to distinguish autochthonous and allochthonous sources of reservoir particulate matter. This study demonstrated that damming largely alters the elemental and isotopic distribution of riverine Sr and would deepen the understanding of Sr biogeochemistry in dammed rivers.

How to cite: Qiu, X. and Wang, B.: Effect of damming on riverine strontium geochemical behavior: Evidence from 87Sr/86Sr analysis, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-2273, https://doi.org/10.5194/egusphere-egu23-2273, 2023.

Streamflow in the glacierized catchments over the Tibetan Plateau receives multi-recharge sources, such as rainfall, melt water from snowpack and glacier, and groundwater. Identifying their contributions to streamflow is challenge but it is vital for understanding streamflow and its composition in response to climate change. In this study, based on high-resolution isotopic (18O) and hydrochemical (Cl-) data in the Yangbajing (YBJ) catchment of the Tibetan Plateau in China, we found that the hydrograph in a year can be separated into five segments, each of which is constituted of two or three dominant recharge sources. Thus, we developed a stepwise EMMA (end-member mixing analysis) method to partition the hydrograph and calculate contributions of water sources to streamflow in each segment of the hydrograph. Results show that the overall contributions of deep and shallow groundwater, melt water from glacier and snowpack, and precipitation are 21.8%, 9.8%, 37.5%, 8.5% and 22.4%, respectively, in a year. Specifically, in the low flow period (January 8 - April 26), streamflow is fed by deep and shallow groundwater (75.2% and 24.8%, respectively). In the early rising period of hydrograph (April 27-June 9) when temperature begins to rise, streamflow fed by deep groundwater decreases and its contribution by snow melt water increases (52.5% and 47.5%, respectively). In the fast-rising period (June 10-June 30), streamflow fed by deep groundwater is minor (4.8%) while snow and glacier melt water becomes the dominant recharge sources to the stream water (52.8% and 42.4%, respectively). In the summer period of July 1- September 23, the streamflow is highest, and the greatest glacier melt water and rainfall contributes to 52.4% and 36% of the stream flow, respectively. In the recession period (September 24 - January 7) when temperature drops and rainfall ceases, streamflow is fed again by deep groundwater and shallow groundwater (45.7% and 54.3%, respectively).

How to cite: Li, G., Chen, X., Gao, M., and Wang, Y.: Identifying contributions of multi- recharge sources to streamflow by using a stepwise approach based on isotopic and hydrochemical signals in a glacierized catchment over Tibetan Plateau, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-2292, https://doi.org/10.5194/egusphere-egu23-2292, 2023.

EGU23-3009 | Posters on site | HS2.2.7

Tracing 36Cl in river water of Eastern Australia 

Dioni I. Cendón, Klaus Wilcken, Stephen J. Harris, Stuart I. Hankin, Mark A. Peterson, and Bryce F.J. Kelly

Chlorine-36, generally expressed as a ratio against stable chlorine (36Cl/Cl x1015), has a half-life of 301 kyr, thus it is a useful tracer for estimating residence time of old groundwater between 50 kyr - 1 Myr. An underutilised use of 36Cl/Cl is as a sensitive tracer of catchment scale processes such as: identifying sources of salinity, weathering, delineating groundwater-surface water interactions, quantifying irrigation infiltration, and identifying anthropogenic inputs.

We highlight the utility of 36Cl/Cl for gleaning insights into regional natural and anthropogenic processes in the Nogoa, Namoi and Murrumbidgee river catchments of eastern Australia. All catchments are within important agricultural regions and are regulated by one or more large reservoirs in their headwaters. The Nogoa River (Lat 23°S) flows east and forms part of the Fitzroy River that meets the Coral Sea near the town of Rockhampton. The Namoi (Lat 30°S) and Murrumbidgee (Lat 35°S) rivers form part of the Murray-Darling Basin and flow westwards (inland) before joining the Darling and Murray Rivers respectively to flow south towards the Southern Ocean. River water was sampled bi-monthly in several stations from the upper to middle reaches of each river during two years between 2017-2020. Sampling took place during drought conditions; 2019 being the driest in ~120 years of instrumental records in many areas. Climatic conditions favoured sampling of baseflow with flows mostly relying on reservoir releases in some cases (Namoi River) until total reservoir and river dryness.

At the ground surface 36Cl can be produced via two main pathways. Typically, the dominant source of 36Cl in surface water is atmospheric, which was produced in the troposphere and stratosphere via interaction of cosmic-ray protons and secondary neutrons with Ar. However, secondary cosmic-ray neutrons can produce 36Cl when they collide with rocks and minerals. These reactions are modulated by the composition of the geological materials and their elevation. The Nogoa and Namoi Rivers have similar basic geological materials in their headwaters at relatively lower altitudes, while the Murrumbidgee has abundant mafic and felsic igneous rocks in the headwaters at higher altitudes.

In general, the Namoi River showed the higher 36Cl/Cl ratios (~650-300) followed by the Murrumbidgee River (~500-200) and the lowest readings were recorded in the Nogoa River (~200-100). These results do not follow simple latitudinal or elevation trends. In this presentation we discuss plausible geological and anthropogenic processes that may account for the observations.

How to cite: Cendón, D. I., Wilcken, K., Harris, S. J., Hankin, S. I., Peterson, M. A., and Kelly, B. F. J.: Tracing 36Cl in river water of Eastern Australia, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-3009, https://doi.org/10.5194/egusphere-egu23-3009, 2023.

Streamwater temperature is an important water quality parameter, and controls metabolic and other reaction processes. In urban systems, streamwater temperature has been shown to depend substantially on the near-stream land cover: Riparian buffer zones may cool urban streams, while effluent from wastewater treatment plants is known to raise streamwater temperatures. Groundwater contributions can decrease summer and increase winter streamwater temperature, essentially acting as a temperature buffer. In consequence, streamwater temperature is highly dependent on the specific layout of the urban system.

Streamwater temperature fluctuates on annual, seasonal, daily, and diurnal basis, however, storm events may additionally impact streamwater temperature on short time scales. The timing and patterns of streamwater temperature responses to storm events relative to the hydrograph may differ from event to event. Because urban infrastructure is typically designed to rapidly route water to the sewer network to avoid flooding, streamwater temperature response patterns are likely related to event- and site-specific water sources contributing to streamflow. Changes in temperature patterns could thus be linked to changes in water release processes. If we disentangle the various empirical relationships revealing potential physical controls on how water is conveyed to streams in urban areas, temperature could potentially be used as a cheap tracer of water sources and pathways in urban systems, which are typically difficult to assess.

We investigated and quantified different streamwater temperature response patterns to stormflow, to understand predictors of diverse streamwater temperature responses to summer storms. We found that streamwater temperature shows varied response patterns to storms, including temperature increases and decreases. Some of the temperature increases may take the shape of rapid “heat pulses”, a short but relatively high magnitude temperature increase and subsequent drop at the start of the hydrograph. Streamwater temperature responses to storms were event-specific and could be clearly linked to event characteristics. Understanding the streamwater temperature response can thus aid in understanding urban source contributions to streamflow, because the mixing of sources – and the timing of this mixing process – causes a unique streamwater temperature pattern. Likely sources contributing to the streamwater temperature patterns are ponded surface waters and storm drains, or cooler water from the shallow subsurface. These findings indicate that streamwater temperature may be used as a cheap but effective tracer informing the contributions from different source zones in urban catchments.

How to cite: Knapp, J. and Kelleher, C.: Hunting for heat pulses: streamwater temperature responses to summer storms as tracer for urban water sources, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-3190, https://doi.org/10.5194/egusphere-egu23-3190, 2023.

EGU23-4596 | ECS | Posters on site | HS2.2.7

Tracer-aided hydrological model in large mountainous catchments 

Yi Nan and Fuqiang Tian

Issues related to large uncertainty and parameter equifinality have posed big challenges for hydrological modeling in cold regions where runoff generation processes are particularly complicated. Tracer-aided hydrological models that integrate the transportation and fractionation processes of water stable isotope are increasingly used to constrain parameter uncertainty and refine the parameterizations of specific hydrological processes in cold regions. However, the common unavailability of site sampling of spatially distributed precipitation isotopes hampers the practical applications of tracer-aided models in large-scale catchments. We explored the utility of precipitation isotope data derived from the isotopic general circulation models (iGCMs) in driving tracer-aided hydrological models in the typical large basins on the Tibetan Plateau (TP). Results indicate that the model driven by iGCM data can simulate the variation of isotope composition in stream water well. Integrating isotope simulation into the hydrological model helps reduce the modeling uncertainty, improve the parameter identifiability, and improve the quantification of the contributions of runoff components to streamflow.

How to cite: Nan, Y. and Tian, F.: Tracer-aided hydrological model in large mountainous catchments, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-4596, https://doi.org/10.5194/egusphere-egu23-4596, 2023.

EGU23-5004 | Posters on site | HS2.2.7

Better considering tracer distribution within boreholes while FVPDM tests 

Serge Brouyère, Nataline Simon, and Pierre Jamin

Characterizing groundwater fluxes is essential in many hydrogeological studies, especially to assess contaminant transport in the subsurface. In this context, the Finite Volume Point Dilution Method (FVPDM) is a single-well experiment consisting in continuously injecting a tracer into a well and monitoring the evolution of the tracer concentration into the same well. A part of the injected tracer is carried out of the well by the groundwater flow and therefore the higher the tracer dilution, the lower the tracer concentration remaining in the well. In such tests, the water within the tested interval has to be continuously mixed using a mixing pump in order to perfectly homogenize the tracer concentration. Yet in practice, when FVPDM are performed in long-screened boreholes or in very permeable aquifers, it can be technically difficult to maintain a mixing important enough so that the tracer concentration is homogenous along the well. In order to assess the effect of non-perfect mixing on FVPDM results, we introduce here a new discrete model that explicitly considers the recirculation flow rate. The mathematical developments are validated using field measurements resulting of FVPDM tests performed under pumping conditions in a high hydraulic conductivity aquifer. Additionally, a sensitivity analysis was performed in order to assess the effect of recirculation flow rate and to define the limits of the FVPDM and the advantages of the discrete model. Results confirm that it is essential to accurately consider the recirculation flow rate when performing FVPDM in the field. Non-perfect mixing occur as soon as the recirculation flow rate applied is not high enough compared to the groundwater flow rate. In this case, the tracer concentration is not uniform with decreasing tracer concentrations along the tested interval. Since the tracer concentration is measured within the recirculation loop (which helps the mixing of the tracer), neglecting the recirculation flow rate during field data interpretation can lead to significantly overestimate groundwater fluxes if the classical analytical solution is applied to interpret tracer concentration evolution. The discrete model introduced here, which was validated through field measurements, can be used instead to properly estimate groundwater fluxes and assess the tracer distribution within the tested interval.

How to cite: Brouyère, S., Simon, N., and Jamin, P.: Better considering tracer distribution within boreholes while FVPDM tests, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-5004, https://doi.org/10.5194/egusphere-egu23-5004, 2023.

EGU23-5166 | ECS | Posters on site | HS2.2.7

Spatial patterns of stable isotopes in precipitation in Switzerland for the use in hydrological and hydrogeological applications 

Valentina Pelzmann, Albrecht Leis, Marc Schuerch, and Christian Reszler

The stable isotopes of the water molecule, oxygen-18 and deuterium, provide an ideal tracer for water movement and offer a broad range of possibilities to study different processes in the water cycle. To be used in hydrological analyses and modelling the isotope data in precipitation as an “input” function has to be known for the particular catchment or point of interest. This paper presents the development and application of a method interpolating – on a monthly basis – stable isotope data in precipitation of the isotope observation network in Switzerland (ISOT), a module of the NAQUA National Groundwater Monitoring. Several influencing variables (e.g., topographical parameters, climate variables) are tested in a multi-regression framework, and the residuals are interpolated by the use of ordinary kriging. The different variants are tested by cross-validation, splitting the sample in two periods. The tests also provide information about regional differences of the interpolation quality in Switzerland, from which recommendations are made to densify the existing network. Maps of oxygen-18 and deuterium in a 500 m raster are delivered for selected months and years. As a further step in this study, for particular measurement sites of groundwater and surface water with known catchments, the “input” function is determined and compared to the measurements to (i) further validate the interpolation method and, (ii) to improve existing hydrological and hydrogeological information about the location of the recharge area and mean travel times. Also, the “input” functions can be used in hydrological modelling of combined water movement and solute transport in water quality studies.

How to cite: Pelzmann, V., Leis, A., Schuerch, M., and Reszler, C.: Spatial patterns of stable isotopes in precipitation in Switzerland for the use in hydrological and hydrogeological applications, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-5166, https://doi.org/10.5194/egusphere-egu23-5166, 2023.

The travel time of precipitation entering a catchment and leaving it as streamflow varies according to the flow paths it takes, with fast travel times posing a high risk to river water quality. However, investigating influences on travel times is challenging due to the complex water flow through heterogeneous landscapes. Recent studies investigated the fraction of streamflow younger than approximately three months (Fyw) using multi-year data (long-term Fyw) or one-year calculation windows to investigate its time-variability (time-variable Fyw). Nonetheless, the influences on time-variable Fyw and the demarcation between long-term and time-variable are not clear yet. Here, we investigated the long-term, the time-variable, and the Fyw derived from an exponential TTD model of nine major catchments in Central Europe and compared them to catchment characteristics and hydrometeorological variables. Additionally, one- to eight-year calculation windows were used and its impact on the variability of time-variable Fyw was investigated. All three methods of estimating Fyw led to similar results, indicating spatial organization of water flow in Central Europe. Spatial analysis further indicated a negative relationship between Fyw and catchment altitude. Contradicting and lacking spatiotemporal relationships to other investigated variables pointed to possibly unknown, region-specific influences on Fyw. With increasing calculation window size, the variability of time-variable Fyw results decreased. Long-term Fyw depended on the method used to define “long-term”, and many time series related factors, beside the actual target of investigation, i.e., catchment water flow, impacted Fyw. This finding points to difficulties in comparability of studies and catchments when using different window sizes, and we thus recommend future studies to calculate long-term Fyw using all data and one- to several-year time-variable Fyw to facilitate comparability.

How to cite: Stockinger, M. and Stumpp, C.: Lessons learned from the spatiotemporal analysis of long-term and time-variable young water fractions of large Central European catchments, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-5400, https://doi.org/10.5194/egusphere-egu23-5400, 2023.

EGU23-5977 | Orals | HS2.2.7

Groundwater Residence Time in Iceland Depicted by Stable Water- and Carbon Isotopes 

Arny Sveinbjornsdottir, Andri Stefánsson, and Stefán Arnórsson

Iceland is young (the oldest rocks ca 16M years) and characterized by active and widespread volcanism, defined along a Neovolcanic rift zone.  More than 90% of the Icelandic bedrock is of basaltic origin. The permeability of the Tertiary lava pile is 1-4*10-14 m2 but for younger geological formations especially within geothermal areas the permeability is several orders of magnitude higher due to active fissures and faults. The deeper crust has however a very low permeability as pores and fissures are filled with secondary minerals.

 

Due to the high permeability in the upper crust groundwater is often mixed with water components originating from different conditions, of different age and in some cases also affected by water-rock interaction.   Thus groundwater dating is complex and to succeed in estimating groundwater residence time it is of vital importance that interdisciplinary methods are applied to understand the geochemistry, geology and hydrology of a specific groundwater system.

 

In this presentation an overview of using stable water- and carbon isotopes to estimate groundwater residence time is given. It is demonstrated how stable water isotopes including the second order parameter; deuterium excess, can be used to estimate relative ages. Also how radiocarbon age estimations have successfully been used when comprehensive corrections for “dead carbon” from the bedrock and CO2 gas from the deep crust or mantle are applied together with δ13C to correct for modern carbon of organic origin.

How to cite: Sveinbjornsdottir, A., Stefánsson, A., and Arnórsson, S.: Groundwater Residence Time in Iceland Depicted by Stable Water- and Carbon Isotopes, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-5977, https://doi.org/10.5194/egusphere-egu23-5977, 2023.

Stable isotopes (δ18O) and tritium (3H) are frequently used as tracers in environmental sciences to estimate age distributions of water. However, it has previously been argued that seasonally variable tracers, such as δ18O, generally and systematically fail to detect the tails of water age distributions and therefore substantially underestimate water ages as compared to radioactive tracers, such as 3H. In this study for the Neckar river basin in central Europe and based on a >20-year record of hydrological, δ18O and 3H data, we systematically scrutinized the above postulate together with the potential role of spatial aggregation effects to exacerbate the underestimation of water ages. This was done by comparing water age distributions inferred from δ18O and 3H with a total of 12 different model implementations, including lumped parameter sine-wave (SW) and convolution integral models (CO) as well as integrated hydrological models in combination with SAS-functions (IM-SAS).

We found that, indeed, water ages inferred from δ18O with commonly used SW and CO models are with mean transit times (MTT) ~ 1 – 2 years substantially lower than those obtained from 3H with the same models, reaching MTTs ~ 10 years. In contrast, several implementations of IM-SAS models did not only allow simultaneous representations of stream flow as well as δ18O and 3H stream signals, but water ages inferred from δ18O with these models were with MTTs ~ 16 years much higher than those from SW and CO models and similar to those inferred from 3H, which suggested MTTs ~ 15 years. Characterized by similar parameter posterior distributions, in particular for parameters that control water age, IM-SAS model implementations individually constrained with δ18O or 3H observations, exhibited only limited differences in the magnitudes of water ages in different parts of the models as well as in the temporal variability of TTDs in response to changing wetness conditions. This suggests that both tracers lead to comparable descriptions of how water is routed through the system.  our results provide evidence for a broad equivalence of δ18O and 3H as age tracers for systems characterized by MTTs of at least 15 – 20 years. The question to which degree aggregation of spatial heterogeneity can further adversely affect estimates of water ages remains unresolved as the lumped and distributed implementations of the IM-SAS model provided inconclusive results.

Overall, this study demonstrates that previously reported underestimations of water ages are most likely not a result of the use of δ18O or other seasonally variable tracers per se. Rather, these underestimations can be largely attributed to choices of model approaches and complexity not considering hydrological next to tracer aspects. Given the additional vulnerability of SW and CO model approaches in combination with δ18O to substantially underestimate water ages due to spatial aggregation and potentially other, still unknown effects, we, therefore, advocate avoiding the use of this model type in combination with seasonally variable tracers if possible, and to instead adopt SAS-based or comparable model formulations.

How to cite: Wang, S., Hrachowitz, M., and Schoups, G.: Stable water isotopes and tritium tracers tell the same tale: No evidence for underestimation of catchment transit times inferred by stable isotopes in SAS function models., EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-6333, https://doi.org/10.5194/egusphere-egu23-6333, 2023.

EGU23-6934 | ECS | Orals | HS2.2.7

Multi-tracer tests to disentangle mobile-immobile regions in a highly entropic aquifer 

Guglielmo Federico Antonio Brunetti, Christine Stumpp, Carmine Fallico, Gerardo Severino, and Samuele De Bartolo

Anomalous transport processes are frequently observed in radial flow to wells in highly heterogeneous aquifers. This is generally related to the presence of preferential flow pathways that bypass the sediment matrix, thus leading to the formation of fast flow channels, whose magnitude depends on the geological entropy of the system. Tracer tests can be effectively combined with laboratory or field-scale experimental campaigns to understand better the interlinkage between heterogeneity and preferential flow, and to distinguish hydraulically active and inactive regions. Despite considerable past research efforts, these mechanisms are only partially understood. To advance the current understanding, we study transport processes in a laboratory-built highly heterogeneous aquifer under radial flow conditions. The experimental device (200 x 200 x 100 cm) consists of 2527 randomly distributed cells (10 x 10 x 5 cm) of 12 different porous mixtures assembled in 7 layers to form a 35 cm-deep aquifer. This particularly design is intended to maximize the geological entropy of the aquifer, which is equipped with 37 piezometers placed in a radial configuration at different distances from the central (pumping) well. Multiple conservative tracer tests were conducted by injecting a mixture of deuterated water (D2O) and Potassium Bromide (KBr) into different piezometers, and then by analysing the resulting Breakthrough Curves (BTCs) at the central pumping well. BTCs reveals features peculiar of anomalous transport, such as non-symmetry, early peaks and tailing, which depend on the injecting location. This, jointly with the incomplete mass recovery after 48 hours, suggests the simultaneous presence of fast flow in highly conductive regions, which exchange mass with quasi-immobile portions of the aquifer. By dealing with tests individually, it is seen that curves for the two tracers have a similar trend, with almost perfect overlap in the part before the peaks. Differences in the tailing of the BTCs between the two tracers, that exhibit different molecular diffusion coefficients, indicate the importance of diffusion mechanism taking place in the porous matrix.

How to cite: Brunetti, G. F. A., Stumpp, C., Fallico, C., Severino, G., and De Bartolo, S.: Multi-tracer tests to disentangle mobile-immobile regions in a highly entropic aquifer, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-6934, https://doi.org/10.5194/egusphere-egu23-6934, 2023.

Glaciers and permafrost, as core hydrological components of cold regions, are sensitive to climate change and the response in turn affects regional water resources. The ablation of glaciers and permafrost has caused severe environmental problems, including sea level rise, the release of greenhouse gases and further global warming. One poorly understood part that has so far remained underdeveloped is the change natural radioactivity related to ablation processes in cold regions. Radium isotope (223Ra, 224Ra, 226Ra and 228Ra) has been considered as an effective tracer for submarine groundwater discharge into coastal and estuarine environments over years. Unlike the coastal environments, Ra activities and activity ratios seem to show a unique distribution in cold regions. Ra will accumulate with glaciers and permafrost ablation and the activity ratios of 224Ra/228Ra (<1 in cold regions and >1 in coastal regions) indicate that the radioactive equilibrium of short-time Ra isotopes has not yet been reached, which seems to be closely related to glaciers and permafrost thawing. The results of laboratory experiments show that Ra distribution between ice and water will change during freezing, and Ra exchange will occur at the ice-water interface with interaction time increasing. This study aims to explore how natural radioactivity varies in cold regions, and to provide a new tracing method for hydrological investigation in cold regions.

How to cite: Lu, X., Li, L., and Yi, L.: Using radium isotope fingerprinting to trace hydrogeochemistry change and permafrost water cycle in cold regions, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-7578, https://doi.org/10.5194/egusphere-egu23-7578, 2023.

EGU23-8988 | Posters on site | HS2.2.7

Water and nutrient sources in a short stream reach 

Przemyslaw Wachniew, Radosław Szostak, Damian Zięba, and Mirosław Zimnoch

This work stems from several years of research conducted in a medium size lowland catchment of the groundwater-fed Kocinka River in Poland that aimed at quantification of sources and transformations of nitrate pollution. Deconvolution of nitrate sources and transformations at the catchment scale appeared to be difficult because of the mostly diffuse character of groundwater inflows with diverse concentrations of nitrate. Additionally, the hydromorphological characteristics that may affect riverine nutrient cycling change significantly along the river. Therefore, a short, 2.6 km long reach of the upper Kocinka was selected for a more detailed study. This reach is representative of small, channelized streams in urbanized rural areas that receive loads of nutrients and other contaminants from various, often episodic, sources such as farmyard, urban and road runoff, sewage and wastewater disposal, fish ponds. Isotopic compositions of water and nitrate. temperature of water as well as drone-based thermal images were used to characterize sources of streamflow and nitrate. Tracer experiment with tritium and the radioactive phosphorus isotope (32P) provided insights [1] into the significance of transient storage zones in solute transport and the extent of phosphorus removal.

The research has been partially financed from the funds of the "Excellence Initiative - Research University" program at AGH University of Science and Technology.

[1] Zieba, D., & Wachniew, P. (2021). Phosphorus Transport in a Lowland Stream Derived from a Tracer Test with 32P. Water 2021, 13, 1030.

 

How to cite: Wachniew, P., Szostak, R., Zięba, D., and Zimnoch, M.: Water and nutrient sources in a short stream reach, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-8988, https://doi.org/10.5194/egusphere-egu23-8988, 2023.

EGU23-9031 | ECS | Orals | HS2.2.7 | Highlight

An isotope-enabled modeling approach to track snowmelt and groundwater contribution to runoff and root water uptake in a snow dominated mountainous catchment 

Matthias Sprenger, Syvain Kuppel, Rosemary Carroll, Craig Ulrich, and Kenneth Williams

The snow dominated headwaters of the Colorado River are crucial for the water supply of the south-western US. The current water crisis in the Colorado basin makes understanding runoff processes in mountainous regions more necessary than ever. We present how our observations of stable isotopes of water (2H and 18O) in the precipitation, stream-, soil-, xylem-, and groundwater at the East River in the upper Colorado River, combined with multiple hydrometric datasets since 2014 (multi-location stream gauging, groundwater levels, soil moisture snow water equivalent, and eddy-covariance fluxes), can be used to rigourously contrain and evaluate an ecohydrological modelling tool to then identify the time and location of snowmelt and groundwater subsidies to runoff and plant water use. To this end, we deployed a new version of the spatially-distributed, process-based model EcH2O-iso, with a multi-objective model-data fusion procedure. The simulations notably underline the dominant role of snowmelt as a main driver of runoff generation, through its direct contribution to runoff peak during the late spring snowmelt, and to the groundwater recharge that eventually feeds the significant baseflow contribution in this catchment. Our analysis further explores the use of water ages and numerical tracers to better disentangle these cross-seasons carry-over of water between critical zone compartments.

How to cite: Sprenger, M., Kuppel, S., Carroll, R., Ulrich, C., and Williams, K.: An isotope-enabled modeling approach to track snowmelt and groundwater contribution to runoff and root water uptake in a snow dominated mountainous catchment, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-9031, https://doi.org/10.5194/egusphere-egu23-9031, 2023.

EGU23-9057 | Posters on site | HS2.2.7

Geology controls hydrological regime and spatio-temporal origin of surface and subsurface water in two adjacent mountain catchments in Central Italy 

Francesca Manca di Villahermosa, Marco Dionigi, Marco Donnini, Davide Fronzi, Alberto Tazioli, Andrea Spoloar, Clara Turetta, Davide Cappelletti, Chiara Petroselli, Federica Bruschi, Roberta Selvaggi, Daniele Penna, and Christian Massari

Understanding hydrological flow pathways and spatio-temporal origin of surface and subsurface water in catchments with highly fractured geology is particularly challenging. In this work, we relied on the integration of hydrometric measurements with stable oxygen and hydrogen isotope data in two adjacent catchments in the Sibillini Mountains National Park, Central Italy, to better understand the drivers of the catchment hydrological response and the spatio-temporal origin of stream and spring waters. The Ussita catchment is 44 km2 and its highest elevation is 2204 m a.s.l. The Nera catchment is 110 km2 and its highest peak is 2233 m a.s.l. The two rivers merge at the Visso Village, at 615 m a.s.l.

The area is characterised by heavily fissured and fractured calcareous rocks that foster the occurrence of several springs, some of them of karst origin. Both catchments host a dense hydrometerological network. The experimental apparatus is completed with one piezometer, soil moisture probes at five locations, lysimeters at two depths and four throughfall plots under beeches and oaks. Monthly samples for isotopic analysis are being collected since fall 2020 from precipitation at three different elevations and four locations, the streams at different sections, and four springs in the Nera catchment only.

Preliminary results show a distinct hydrological behaviour in the annual streamflow regimes: the Ussita stream slightly reacts only to the largest storms and during intense snowmelt periods, whereas the Nera stream has a very damped response during all the year, revealing a clear buffer effect of the large subsurface reservoir, facilitated by the highly fractured nature of the geological setting. As expected, there is an elevation and seasonal effect in the isotopic composition of precipitation, although the seasonal effect is partly masked by the exceptionally high temperatures occurred in fall 2021. However, the time series of isotope data in stream water show a damped signal and very low seasonal variability in both streams, matching the observed low variability of streamflow. Only the Ussita catchment shows some more enriched outliers likely reflecting runoff response during large storm events. Interestingly, stream and spring samples from both catchments lie along but also above and below the Local Meteoric Water Line, suggesting that the sampled spring and stream water was either originated i) from precipitation fell, infiltrated, and stored well before the collection of the precipitation samples, and released; ii) and/or from areas outside the topographic catchments, and therefore not adequately characterized by the isotopic signal of sampled precipitation. The isotopic composition of the streams and springs is statistically the same, revealing that spring groundwater is the main component of stream runoff. Moreover, the isotope signature of both springs and streams is much closer to that of winter precipitation rather than summer precipitation indicating a major role of winter precipitation in recharging the catchments, consistently with the precipitation seasonal regime. On-going work is assessing the spatial difference in the isotopic composition and quantifying the temporal origin of stream and spring water of the two catchments.

How to cite: Manca di Villahermosa, F., Dionigi, M., Donnini, M., Fronzi, D., Tazioli, A., Spoloar, A., Turetta, C., Cappelletti, D., Petroselli, C., Bruschi, F., Selvaggi, R., Penna, D., and Massari, C.: Geology controls hydrological regime and spatio-temporal origin of surface and subsurface water in two adjacent mountain catchments in Central Italy, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-9057, https://doi.org/10.5194/egusphere-egu23-9057, 2023.

EGU23-9603 | Orals | HS2.2.7

Geologic and geomorphic setting control of water sources and flow paths in mountainous headwater catchments 

Catalina Segura, Zachary Perry, and Jaime Ortega Melendez

Communities downstream from mountainous regions rely on snowmelt for water supply. As climate change reduces the reliability of the snowpack in these regions it is important to understand how and when rain and melt water are stored and released as runoff. In mountainous regions the prediction of water movement is especially complex because water storage capacity and overall water input magnitude and form vary over short distances given variable geology, geomorphology, and topography. We used water stable isotopes (WSI) and water chemistry (ions and cations) to investigate seasonal water sources and contributions in a 64 km2 headwater mountain catchment in Oregon (USA). In one study, we collected > 1,000 synoptic samples between 2021 and 2022 across different seasons in 12 headwater streams (600–1,200 m in elevation and drainage areas 0.1–5 km2) and analyzed them for WSI. Results demonstrate that despite season there are localized variations in WSI within less than 1-km2 between catchments underlain by similar geology but characterized by different geomorphic history of mass wasting events (landslides and earthflows). We also observed weak relationships between elevation and WSI in some streams suggesting that their sources of baseflow are not directly controlled by seasonal precipitation but by differences in storage over spatially variability geomorphic history.  In a second study, we investigated relative streamflow contributions from five tributaries (0.7–17 km2) over the whole year based on weekly WSI and water chemistry in grab and precipitation samples. We found strong differences across streams; the most interesting was a spring-fed stream, whose water contribution varies widely throughout the year, resembling a snowmelt system (with high relative water input in the summer). The depleted WSI signal and relatively high cations concentrations of this stream reveals higher elevation snowfall is moving to the stream through relatively long flow paths. This stream is underlain by porous lava flows demonstrating a strong geologic control on runoff generation. The contribution of this stream to the whole watershed is over 27 times larger in the summer compared to any other season. This finding challenges the idea of streamflow scaling with drainage area because the effective drainage area of this stream varies between 0.8 and 47 km2 while the topographic derived drainage area is 0.7 km2.

How to cite: Segura, C., Perry, Z., and Ortega Melendez, J.: Geologic and geomorphic setting control of water sources and flow paths in mountainous headwater catchments, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-9603, https://doi.org/10.5194/egusphere-egu23-9603, 2023.

EGU23-9949 | Posters on site | HS2.2.7

Timing of an Alpine water cycle unraveled by water isotopes and age-dating tracers (3H, 3He, 14C, CFCs, SF6 and 222Rn), Eastern Alps, Austria 

Martin Kralik, Daniel Elster, Ramon Holzschuster, and Christine Stumpp

Alpine regions are important as “water towers” in regional water supply of clean groundwaters due to their increased precipitation rates and their unspoiled environment. However, they are often characterised by complex geology structures, covered by down-sliding glacio-fluvial sediments. Groundwater recharge conditions and mean transit times (MTTs) are fundamental components of mountain watershed hydrological systems. Here, we used measurements of stable water isotopes of precipitation, pore water, surface and groundwater. In addition, measurements of environmental age tracers (222Rn, CFCs, 3H, 3He, 4He and 14C) were performed to investigate groundwater MTTs from springs in glacio-limnic sediments (<20 m) and deeper wells (>20 m) located along a mountainous hillslope (1,400-800 m) within the Subersach watershed near Sibratsgfäll, Bregenzer Wald, Austria. The near surface spring waters contain 3H and CFCs in excess. The deeper artesian well samples contain 3H and CFCs, in addition to elevated terrigenic 4He and low 14C values, suggesting a mixture of waters characterised by residence times that are modern (<70 years) and pre-modern (>70 years). We show that binary-mixing MTT models with distinct young and old fractions are needed to explain the full suite of environmental tracers, further supporting the importance of groundwater mixing processes.

The vertical unsaturated infiltration in silt/sand dominated glacio-lacustrine sediments were estimated by seasonal variation of 2H/18O-isotopes in pore-water to be 1-4 m/year approximately. Precipitation in the Flysch dominated area at higher altitudes is transported partly as mountain bloc recharge and ascends into the glacial sediments, indicated by temperatures 2-3° C higher than the mean surface temperature. The MTTs of the shallow groundwater (<20 m) estimated by a combination of isotopes 2H/18O, 3H/3He, 13C/14C and tracer gases (CFC, SF6) indicate ages between some months and 4 years. Radon measurements identify springs supplied by very young drainage or surface waters. Deeper (>20 m) artesian wells in the western part are dominated by MTT older than 70 years.

The research project “Understanding of Extreme Climatological Impacts from Hydrogeological 4D Modelling” (EXTRIG) was funded by the Austrian Academy of Sciences.

How to cite: Kralik, M., Elster, D., Holzschuster, R., and Stumpp, C.: Timing of an Alpine water cycle unraveled by water isotopes and age-dating tracers (3H, 3He, 14C, CFCs, SF6 and 222Rn), Eastern Alps, Austria, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-9949, https://doi.org/10.5194/egusphere-egu23-9949, 2023.

EGU23-10782 | ECS | Orals | HS2.2.7

Characterizing landscape influences on hydrological flow pathways in a peri-urban Mediterranean catchment 

Amanda Carneiro Marques, Carla Sofia Santos Ferreira, Núria Martínez-Carreras, Zahra Kalantari, and Christian David Guzman

Stable isotopes are an important tool to describe the movement of water through the hydrosphere. They are used as tracers to characterize hydrograph properties. In field studies, stable isotope analyses using hourly and bulk end-member calculations can be used to estimate baseflow/precipitation contributions and to relate hydrograph response to land cover across a watershed. To enable proper planning of paved surface expansions and the nature of storm drainage systems, advanced understanding of the influences of spatial land-use patterns on Mediterranean streamflow regimes are needed to support water management in peri-urban catchments. This study focuses on Ribeira dos Covões, a small peri-urban catchment (around 6 km2), located in central continental Portugal. The catchment is composed of sandstone in the west portion (56%) and limestone in the east portion (41%), with some alluvial deposits (3%) in the main valleys. Flow and precipitation data were collected every five minutes during storms for several years. In 2018, sampling campaigns also included the collection of pre-event, event, and post-event water stable isotopes in different seasons of the year for streamflow at four sites, representing distinct land coverage and lithological landscape combinations. Preliminary results using precipitation and baseflow fraction calculations based on oxygen-18 measurements show that the catchment outlet provides a 49% baseflow contribution (old water fraction) at the beginning of the dry season and 36% in the wet season. An 85% baseflow contribution was estimated for Quinta (mainly forest area in sandstone) during the dry season, and 64-74% for Espírito Santo (largely urban in sandstone) during the wet season. The baseflow contribution at Porto Bordalo (urban area in limestone) is not significant because the flow is controlled by precipitation. Further investigation will involve connecting the results of most recent stable isotope data analyses to the approaches that were used in the past (e.g. separation of baseflow based on low-pass digital filters). Such connection will clarify streamflow response from distinct peri-urban pattern and lithological landscape combinations and their contributions to catchment runoff, aiming to explore the similarities and differences among these methods and quantify the effects of hydrological regime and land use changing patterns over time.

How to cite: Carneiro Marques, A., Ferreira, C. S. S., Martínez-Carreras, N., Kalantari, Z., and Guzman, C. D.: Characterizing landscape influences on hydrological flow pathways in a peri-urban Mediterranean catchment, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-10782, https://doi.org/10.5194/egusphere-egu23-10782, 2023.

EGU23-10980 | Posters on site | HS2.2.7

A multi-well tracer test for characterizing the preferential flow of the shallow aquifers in the Tatun Volcanic Area 

Pei-Yun Tseng, Yi-Ling Chen, and Ching-Huei kuo

A multi-well tracer test was conducted in a volcanic area where is mainly composed of sedimentary rocks units and tuff breccia with attitude of the N46E, 18S. in Northern Taiwan. The distance between the injection well #14 and monitoring wells #-2 and #6 are 236 and 682 m, respectively.

A Bimodal breakthrough curve was received from both wells indicating the existence of more than one channel in the system. Surprisingly, the first peak arrives simultaneously at both wells with almost a 3 times difference in distance. A much fast flow between Well #14 and #6 was found. This result matches the local orientation of the formation and may show strong geology control groundwater flow of the region resulting in a preferential flow. With the moment analysis, the difference in communication between the injection well and the two monitoring wells can be depicted by 50% of the flow circulation coming from 25% and 30% storage capacity for Well #2 and Well #6, respectively implying that groundwater flows through more fractures between Well #14 and 6.  An obvious tailing breakthrough curve of Well #6 also reflects more fractures than that of Well #2.

How to cite: Tseng, P.-Y., Chen, Y.-L., and kuo, C.-H.: A multi-well tracer test for characterizing the preferential flow of the shallow aquifers in the Tatun Volcanic Area, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-10980, https://doi.org/10.5194/egusphere-egu23-10980, 2023.

Stable isotopes, δ2H and δ18O, of precipitation and groundwater in two adjacent catchments, the north, and south, in the Tatun Volcanic Group, Taiwan were used to characterize the regional groundwater. The results show that the isotopic composition of precipitation exhibits seasonal variations, which suggests different sources of moisture generation for the rainfall in the study area. In general, the north catchment shows more enriched isotopic characteristics than that of the south one.  

The seasonal variations of precipitation, with lighter in summer, arise from changes in isotopic water vapor composition associated with the seasonal activity of the Asian monsoon which was used in estimating the mean residence time (MRT) of groundwater in the region. The preliminary results show that the average MRT of the study area ranges from 180 to 500 days in the north catchment while it is 180 to 900 days in the south catchment.

How to cite: Chen, Y.-L. and Kuo, C.-H.: Using stable isotopes and mean residence time to characterize the groundwater system in the Tatun Volcanic Group, Taiwan, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-11069, https://doi.org/10.5194/egusphere-egu23-11069, 2023.

EGU23-11080 | Posters on site | HS2.2.7

Tracer test for evaluating the shallow groundwater flow in a volcanic area, Taiwan 

Ching-Huei kuo, Pei-Yun Tseng, and Yi-Ling Chen

A tracer test, involving conservative and reactive, was conducted in a volcanic area in Northern Taiwan to evaluate shallow groundwater characteristics. The distance between injection Well #14 and monitoring Wells #2 and #6 are 236 and 682 m, respectively.

  A breakthrough curve was received from both wells for conservative tracer, 2,6NDS, while the reactive one was obtained only at Well#6 indicating the existence of heterogeneity in groundwater and fracture distribution in the region.  A much fast flow between Well#14 and #6 was found as the first peak arrives at the same time with a 3 times difference in distance.  This result matches the local orientation of the formation and may show strong geology control groundwater flow of the region resulting in a preferential flow. However, a chaser influence was identified by an irregularity of breakthrough curves for both wells.

How to cite: kuo, C.-H., Tseng, P.-Y., and Chen, Y.-L.: Tracer test for evaluating the shallow groundwater flow in a volcanic area, Taiwan, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-11080, https://doi.org/10.5194/egusphere-egu23-11080, 2023.

EGU23-11098 | Posters on site | HS2.2.7

Efficacy of Halon-1301 as an age tracer - Multi-tracer evaluation in Shimabara springs 

Makoto Kagabu, Shinsuke Kojima, and Miku Ishibashi

For sustainable use and management of local water resources, it is essential to clarify the groundwater flow system and its scale, and one of the effective methods is to estimate the residence time. One of the methods to clarify the residence time is to use "age tracers", which are mainly used for chlorofluorocarbons (CFCs) and sulfur hexafluoride (SF6) in Japan. Since each tracer has its own advantages and disadvantages, a combination of several tracers is necessary to improve the accuracy of the estimated residence time, and the development of new age tracers is required. Overseas studies such as Beyer et al. (2014) have begun to report the application of Halon-1301 as a new age tracer, but there are no such reports in Japan. Therefore, we evaluated the applicability of the Halon-1301 method in Japan by evaluating the residence time of five of the Shimabara springs in Shimabara City, Nagasaki Prefecture, using multiple age tracers.

How to cite: Kagabu, M., Kojima, S., and Ishibashi, M.: Efficacy of Halon-1301 as an age tracer - Multi-tracer evaluation in Shimabara springs, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-11098, https://doi.org/10.5194/egusphere-egu23-11098, 2023.

EGU23-12064 | ECS | Posters on site | HS2.2.7

Evaluation of the mechanism of residence time change of Shimabara springs based on high frequency water sampling survey 

Miku Ishibashi, Koichi Sakakibara, and Makoto Kagabu

It is essential to clarify the groundwater flow system and its scale for the sustainable use and management of local water resources. One effective method is to estimate the residence time of groundwater. The Shimabara springs exist in Nagasaki Prefecture, Japan, and its water quality has been characterized over time. However, there have been few studies on water quality characteristics and isotope variations with fine resolution in a region such as Japan, where seasonal changes in precipitation are observed. Therefore, we conducted periodic water sampling at five locations in the Shimabara Springs at a frequency of about once a month, and evaluated water quality characteristics and isotope variations. CFC-12, an age dating tracer, was also used for a multifaceted study. During the observation period, we observed precipitation that was more than five times larger than the normal year, and in response to this, we were able to identify springs that showed changes in various hydrologic parameters. In the presentation, we will discuss the relationship between precipitation, residence time, and water quality, and present a schematic diagram of the mechanism of this spring discharge.

How to cite: Ishibashi, M., Sakakibara, K., and Kagabu, M.: Evaluation of the mechanism of residence time change of Shimabara springs based on high frequency water sampling survey, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-12064, https://doi.org/10.5194/egusphere-egu23-12064, 2023.

EGU23-12174 | Orals | HS2.2.7

Performance of the Picarro CRDS water isotope analyzer for δ2H tracer studies 

Magdalena E. G. Hofmann, Joyeeta Bhattacharya, Jan Woźniak, Jinshu Yan, and Ruthger van Zwieten

The Picarro water isotope analyzers (L2130-i/L2140-i) have become a standard technique to measure the natural abundance of δ18O, δ2H and 17O-excess of water isotopes in climate, environment, and hydrological studies. In addition, some applications require to measure highly enriched δ2H water isotope samples, e.g., when tracing water flows in hydrology. In this case, the 2H/1H ratio is used as a tracer when fluorescent tracers are not an option, e.g., when tracing drinking water.

Measuring highly enriched water samples with optical spectroscopy comes along with two challenges: (i) the memory effect, the carryover from small fractions of water from one sample to another, and (ii) the spectroscopic limits of the analyzer. Here, we address both challenges by characterizing the memory effect for highly enriched δ2H samples considering the recently developed express mode that allows to reduce/remove the memory effect at a much faster rate compared to the standard mode [1, 2] and by reviewing the spectroscopic limits of the analyzer.

In this study, we tested the performance of the Picarro L2130-i water isotope analyzer for a set of samples with varying 2H/1H ratios of 0.1 to 2.0% (corresponding to δ2H values of about 6,000 to 130,000‰). We found that (i) the analyzer shows an excellent linearity over a high δ2H enrichment range (up to 130,000‰); (ii) the analyzer shows a negligible concentration dependence at high enrichment levels; (iii) the spectroscopic limits of the analyzer can be extended by reducing the injection volume (<1.8uL); (iv) the memory effect can be reduced significantly when using the express mode compared to the standard mode.

Our results show that the Picarro L2130-i water isotope analyzer is an adequate tool for measuring highly enriched δ2H water samples, and we will discuss best practices when measuring these samples.  

 

References

[1] Hofmann, M. E. G., Lin, Z., Woźniak, J., and Drori, K.: Improved throughput for δ18O and δD measurements of water with Cavity Ring-Down Spectroscopy, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-14254, https://doi.org/10.5194/egusphere-egu21-14254, 2021.

[2] Landais, A., Minster, B., Zuhr, A., Hofmann, M., and Fourré, E.: Performances of express mode vs standard mode for δ18O, δD and 17O-excess with a Picarro analyzer, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-4278, https://doi.org/10.5194/egusphere-egu22-4278, 2022.

How to cite: Hofmann, M. E. G., Bhattacharya, J., Woźniak, J., Yan, J., and van Zwieten, R.: Performance of the Picarro CRDS water isotope analyzer for δ2H tracer studies, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-12174, https://doi.org/10.5194/egusphere-egu23-12174, 2023.

EGU23-12668 | Orals | HS2.2.7

Testing a conceptual model of runoff generation processes for a small pre-alpine catchment with tracer data 

Giulia Zuecco, Chiara Marchina, Ylenia Gelmini, Daniele Penna, Marco Borga, and Ilja van Meerveld

Conceptual models of catchment hydrological functioning are crucial to understand and predict runoff and the tracer responses during rainfall events, and thus for sound water resources management and pollution mitigation measures. In this study, we use hydrometric and tracer data (stable isotopes, major ions and electrical conductivity (EC)) collected in the Ressi catchment, a 2-ha watershed in the Italian pre-Alps, to test our existing conceptual model of runoff generation mechanisms. This model was based on previous hydrometric measurements and isotope data for selected events and highlights the importance of precipitation and antecedent conditions for hillslope-riparian zone-stream connectivity. More specifically, we determined if the temporal variability in the concentration-discharge relations can be explained by event characteristics, i.e., rainfall event size, intensity, and antecedent moisture conditions.

The Ressi catchment is characterized by high seasonality in runoff response, due to the seasonality in rainfall (high in fall) and evapotranspiration (high in summer). Discharge and rainfall have been measured continuously since August 2012. Stream water, precipitation, shallow groundwater and soil water samples were collected for tracer analyses during 20 rainfall-runoff events between September 2015 and August 2018. All samples were analyzed for EC, isotopic composition (2H and 18O) and major ion concentrations. To investigate the possible controls on the concentration-discharge relations, we determined the main event characteristics (e.g., total event rainfall, rainfall intensity, antecedent soil moisture and depth to water table, runoff coefficient) for each event.

Based on previous applications of isotope- and EC-based hydrograph separation in the Ressi catchment, we expected different dynamics of the major ions in stream water, depending on the magnitude of the rainfall-runoff events. For all major ions, we hypothesized a dilution effect, and a more marked response for large, long duration events with wet antecedent conditions. The temporal dynamics of calcium, magnesium, sodium and sulfate concentrations confirmed our hypotheses. On the contrary, nitrate, potassium and chloride concentrations sometimes increased at the onset of the event, before a later dilution. These temporal dynamics led to complex hysteretic relations with discharge that could not be explained by the event characteristics. We attribute the rapid increase in the concentrations of these solutes to a quick flushing from the dry parts of the stream channel and the near surface-soil layers of the riparian zone at the onset of the event. The revised conceptual model for the geochemical response of this catchment should, therefore, include a rapid flow pathway that leads to the mobilization of nitrate, chloride and potassium ions, and describe the rapid establishment of hydrological connectivity along the streambed and the near-channel zones.

 

Keywords: concentration-discharge relation; major ions; electrical conductivity; stable isotopes; hysteresis; forested catchment.

How to cite: Zuecco, G., Marchina, C., Gelmini, Y., Penna, D., Borga, M., and van Meerveld, I.: Testing a conceptual model of runoff generation processes for a small pre-alpine catchment with tracer data, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-12668, https://doi.org/10.5194/egusphere-egu23-12668, 2023.

EGU23-12966 | ECS | Posters on site | HS2.2.7

Groundwater Flow System in Klang River Watershed, Kuala Lumpur, Malaysia 

Mariko Saito, Maki Tsujimura, Norsyafina Roslan, Kamarudin Samuding, Faizah Che Ros, and Ismail Yusoff

This study aims to clarify the groundwater recharge and flow processes in a basin located in a tropical humid area with a complex geological setting. We conducted intensive sampling campaigns for river water and groundwater during three different time periods in the relatively dry season (September 2019, January-March 2020, and August-September 2022). The 40 river water samples and 25 groundwater samples were taken from the upper-stream area with an altitude of 527 m to the downstream area with an altitude of 10 m. The oxygen-18 (δ18O) and deuterium stable isotopic compositions and inorganic constituent concentrations were determined on all water samples. We also used the monthly stable isotopic compositions in rainwater observed at a location with an altitude of 26 m, 15 km apart from the Klang River basin, by the Global Network of Isotopes in Precipitation database (GNIP), IAEA. These chemical compositions were used as tracers to investigate the groundwater recharge and flow system. The deep groundwater shows a lower δ18O than the volume-weighted mean of rainwater and higher ion concentrations, whereas the shallow groundwater shows a higher δ18O and lower ion concentrations. This suggests that the deep groundwater with low δ18O seems to be recharged in the mountainous area with an altitude ranging from 70 to 1421 m. Additionally, we conducted a principal component analysis and cluster analysis using inorganic constituent concentrations and stable isotopic compositions, showing that the deep and shallow groundwater samples are classified into two groups. This shows that the deep groundwater in the downstream area is recharged mainly in the mountainous areas with the highest altitude of 1421 m, and the shallow groundwater is recharged partly in the hilly areas with the highest altitude of 250 m. We believe our study serves new findings on the groundwater flow system in mega-cities of tropical climate regions.

How to cite: Saito, M., Tsujimura, M., Roslan, N., Samuding, K., Che Ros, F., and Yusoff, I.: Groundwater Flow System in Klang River Watershed, Kuala Lumpur, Malaysia, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-12966, https://doi.org/10.5194/egusphere-egu23-12966, 2023.

EGU23-12983 | ECS | Posters on site | HS2.2.7

River influence on groundwater – head changes vs. chemical changes 

Johannes Christoph Haas, Alice Retter, Steffen Birk, Heike Brielmann, and Christine Stumpp

High correlations between river stages and groundwater levels are often seen as an indicator of surface water influence on groundwater. However, such a simple correlation does not necessarily provide information about the nature of said influence, i.e. whether the groundwater hydraulic head only follows the changes in river level or if there is also significant inflow of surface water into the aquifer.

In two large sampling campaigns (early summer and late autumn) covering 45 groundwater and 11 river sites stretching from the alpine region to the foreland basins of the Mur river, Austria using surface water-borne wastewater indicators, stable isotopes of water and selected microbial indicators [1], we show that the influence of surface water intrusion into the shallow aquifer often can be traced hundreds of meters away from the river. Still, at some wells in close vicinity to the river (< 50m) with high correlation of water levels (R > 0.9), isotope data and wastewater indicators hint at no direct surface water influence.

However, one could argue that even at these locations it is plausible that a flood event in the river might reverse flow temporarily, signs of which will not be found by irregular sampling at an inappropriate temporal scale, as the river-borne substances will be quickly flushed out of the shallow aquifer due to the generally effluent conditions. Operating a high-resolution UV-Vis sensor, monitoring nitrate and other key components, we show that direct river influence in the given case still is unlikely.

[1] https://doi.org/10.5194/egusphere-egu21-13111

How to cite: Haas, J. C., Retter, A., Birk, S., Brielmann, H., and Stumpp, C.: River influence on groundwater – head changes vs. chemical changes, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-12983, https://doi.org/10.5194/egusphere-egu23-12983, 2023.

EGU23-13138 | ECS | Orals | HS2.2.7

Transient effect on groundwater age distribution – age measurements disprove steady state assumption 

Tamara Kolbe, Jean Marçais, Virginie Vergnaud, Barbara Yvard, Alejandro Chamorro, and Kevin Bishop

Groundwater ages are key indicators for flow and transport processes as well anthropogenic and geogenic solutes that impact groundwater quality. Commonly, lumped parameter models (LPMs) are applied to interpret environmental tracers, like chlorofluorocarbons (CFCs) or tritium. LPMs require a steady state assumption and they are less complex, computational demanding and data intensive compared to transient numerical models. But when steady-state assumptions are valid for groundwater age simulations is questionable.

An initial sampling campaign of CFCs measured in 9 wells at different depths on a 0.47 km2 subcatchment of the Krycklan catchment in 2017 revealed a groundwater age stratification with depth that was representative for the area1. Mean groundwater ages at the water table (2-6 meters depth) in the unconsolidated till overburden were already 30 years and increased with depth to the deepest sampling at 30 meters. These results indicate a lag of rejuvenation caused by a subsurface discharge zone that evolves between two soils types with different hydrogeological properties. The comparison of the steady-state numerical simulation and LPM has proven that the LPM yields an overall recharge rate and estimation of the extent of the subsurface discharge zone.  Seasonal changes of recharge were not expected to impact the age stratification. But repeated sampling in 2021 and 2022 has shown a clear shift of the groundwater age stratification. Numerical modeling is used to understand that transient effect.

 

References:

1Kolbe, T, Marçais, J, de Dreuzy, J-R, Labasque, T, Bishop, K. Lagged rejuvenation of groundwater indicates internal flow structures and hydrological connectivity. Hydrological Processes. 2020; 34: 2176– 2189. https://doi.org/10.1002/hyp.13753

 

How to cite: Kolbe, T., Marçais, J., Vergnaud, V., Yvard, B., Chamorro, A., and Bishop, K.: Transient effect on groundwater age distribution – age measurements disprove steady state assumption, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-13138, https://doi.org/10.5194/egusphere-egu23-13138, 2023.

EGU23-13279 | Posters on site | HS2.2.7

River and Groundwater Interaction in the mid-stream area of Tama River, Tokyo, Japan 

Taiga Suzuki, Maki Tsujimura, Keisuke Sato, Hiroko Asakura, and Kosuke Nagano

This study aims to evaluate a role of Tama river in groundwater recharge by using multi-tracer approach and statistical analysis in a mid-stream area of Tama River, western Tokyo.

 

We performed an intensive sampling of river water, groundwater and spring water in the mid-stream area of Tama River watershed including tributaries, Akikawa River and Asakawa River from May through September 2022, and totally 21 of river water, 35 of groundwater and 17 of spring water were sampled, and stable isotopic compositions (δ2H, δ18O), inorganic constituent concentrations were determined on all water samples.

 

The d18O of Tama River water increases with flow especially after joining of the tributaries. The chemistry of Tama River, shallow groundwater and the spring water is characterized dominantly by Ca-HCO3 type, whereas the deep groundwater shows a Na-HCO3 or Na-Ca-Mg-HCO3 type dominantly.

 

We applied End Member Mixing Analysis to estimate the contribution ratio of Tama River water to the shallow groundwater in the mid-stream area using d18O and SiO2 as tracers, and we selected the volume weighted mean of precipitation, mean of Tama river water and the groundwater taken in the border between mountain and plain area. The contribution ratio of river water to the total groundwater recharge ranges from 21% to 83%.

 

Also, we performed a principal component analysis using all analyzed components to evaluate the category of the water chemistry considering the river water and the groundwater interaction. Further, we conducted hierarchical clustering analysis using PCA results.

 

Consequently, the all of water samples are classified in 6 groups, and the shallow groundwater is categorized in the same group as the river water.

 

The results show clearly that the Tama River water contributes dominantly to the shallow groundwater in the mid-stream area, and the river water partly recharges the deep groundwater. It seems to be due to the decline of the major aquifers from south-west to north east directions, which is from river to mid-stream plain area.

How to cite: Suzuki, T., Tsujimura, M., Sato, K., Asakura, H., and Nagano, K.: River and Groundwater Interaction in the mid-stream area of Tama River, Tokyo, Japan, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-13279, https://doi.org/10.5194/egusphere-egu23-13279, 2023.

EGU23-13281 | ECS | Posters on site | HS2.2.7

Drivers and controls of greenhouse gas dynamics in subarctic, alpine catchments 

Andrea L. Popp, Nicolas Valiente Parra, Kristoffer Aalstad, Sigrid Trier Kjær, Norbert Pirk, Alexander Eiler, Peter Dörsch, Dag Olav Hessen, and Lena Merete Tallaksen

Headwater catchments are known to substantially contribute to global carbon and nitrogen cycles through transport, storage, and direct emissions of greenhouse gases (GHGs). Despite extensive research on GHG dynamics in headwater systems, their drivers and controls remain elusive, particularly in cold region environments that are undergoing rapid transformations. Cryospheric changes, such as alterations in snowpack mass, are known to be strongly coupled with the hydrological cycle. However, we have limited insight into the nexus between snow cover changes, source water contributions (e.g., groundwater and glacial meltwater) to surface waters and associated biogeochemical cycling. 

To better understand the hydrological and biogeochemical changes in cold regions, we obtained field- and satellite-derived data from two sub-arctic catchments (one glaciated, one non-glaciated) in the north-western part of the Hardangervidda mountain plateau (South Central Norway). With this work, we aim to obtain an improved understanding of the impact of snow cover on GHGs dynamics in high-latitude, alpine catchments. During late summers in 2020 and 2021, we analysed various water sources including streams, lakes, groundwater, snow and ice for environmental tracers (major ions, stable water isotopes, radon-222) and GHGs  (CO2, CH4 and N2O). The combination of environmental tracer data with a Bayesian end-member mixing model allowed us to partition water source contributions to streams and lakes. To estimate snow cover anomalies between 2020 and 2021 compared to a five-year mean, we retrieved fractional snow cover durations (FSCDs) from 2016 to 2021 by applying a spectral unmixing algorithm to merged Sentinel-2 and Landsat 8 imagery over Finse. 

According to the satellite-derived data, 2020 was exceptionally snow-rich, while 2021 was a normal year. Our results indicate that GHG saturations distinctively differ among different water sources (e.g., lakes and streams), of which most are supersaturated. Thus, surface waters act as net sources for GHGs to the atmosphere, at least for the time windows of our sampling campaigns. Gas saturations distinctively differed between the glaciated and the non-glaciated catchments as well as between snow-rich and normal snow conditions. Groundwater is the most CO2 and CH4 supersaturated water source. However, groundwater only marginally contributed to surface waters and is thus not a major driver of GHGs emissions. Consequently, we hypothesise that snow cover, glacial meltwater, and resulting differences in subsurface water routing control GHGs dynamics at our study site. These findings provide new insights into the linkage between snow cover and the associated different hydrologic conditions and GHGs dynamics in high-latitude and alpine inland waters. 

How to cite: Popp, A. L., Valiente Parra, N., Aalstad, K., Trier Kjær, S., Pirk, N., Eiler, A., Dörsch, P., Hessen, D. O., and Tallaksen, L. M.: Drivers and controls of greenhouse gas dynamics in subarctic, alpine catchments, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-13281, https://doi.org/10.5194/egusphere-egu23-13281, 2023.

EGU23-13510 | ECS | Posters on site | HS2.2.7

Comparison of Runoff characteristics in bare and vegetated headwater catchments, Northern Alps, Japan 

Mayu Fujino, Koich Sakakibara, Maki Tsujimura, and Keisuke Suzuki

We evaluated an effect of alpine vegetation on water storage and runoff characteristics in alpine zones. We sampled rainwater, snowmelt water and runoff water from bare and vegetated catchments in August and October 2019 in headwater catchment of Mt. Norikura, Japan. We compared the water chemistry of runoff water from bare catchments and vegetated catchments. The pH, electrical conductivity and total dissolved ion concentrations of runoff water from vegetated catchments were higher than those from bare catchments, suggesting a longer contact time between water and the regolith in the vegetated catchments. We also applied two-component hydrograph separation to calculate the contribution of precipitation and groundwater components to the runoff water. The contribution of groundwater component to runoff water ranged from 0.8% to 63.8% in the vegetated catchments, whereas that ranged from 0.3% to 14.6% in the bare catchments. Furthermore, the groundwater contribution was higher in the area with vegetation predominantly over the bare area in each catchment. This suggests that the runoff water has longer transit time in the vegetated areas than the bare areas. In the vegetated areas, the subsurface water should flow with longer transit time due to an existence of well-developed regolith with coarse-grained sediments as compared with that in bare areas. Thus, the alpine vegetated area has a higher water storage function than the bare area. Our results show that we need to consider the vegetation and regolith conditions and subsurface flow processes to the hydrological processes in mountainous areas, especially in alpine zones.

How to cite: Fujino, M., Sakakibara, K., Tsujimura, M., and Suzuki, K.: Comparison of Runoff characteristics in bare and vegetated headwater catchments, Northern Alps, Japan, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-13510, https://doi.org/10.5194/egusphere-egu23-13510, 2023.

EGU23-13702 | ECS | Posters on site | HS2.2.7

New estimation to the turnover time of Lake Ohrid: an environmental isotope and noble gas study 

Marianna Túri, Marjan Temovski, Gabriella Ilona Kiss, István Csige, and László Palcsu

We present noble gas composition and environmental isotope signature (δ18O, δ2H, δ15NNO3-, 3H) of waters sampled from Lake Ohrid. The lake is one of Europe's deepest (max. depth ~288 m) and oldest lake, situated in southeastern part of the continent at the border between Albania and North Macedonia.

The sampling campaign was in the summer of 2017, when 100 water samples were taken from 19 depth profiles (at depths of 5 m, 25 m, 50 m, 100 m, 150 m, 200 m and 250 m) for water stable isotopes, noble gases, and tritium. Samples for δ15NNO3- measurement of nitrate were collected at 7 m and 27 m depth.

Lake Ohrid, situated between Galičica Mt. to the east and Jablanica and Mokra Mts to the west, is a large (surface area ~350 km2), oligotrophic, and one of the most voluminous lakes (~55 km3) and together with Lake Prespa represents the biggest water system in the Balkan region. Numerous studies have been carried out on the hydraulic connection between the two lakes using stable isotopes and hydrological modelling. The water balance of Lake Ohrid is dominated by inflow from karst aquifers, direct precipitation and with slightly smaller shares from river runoff. Lake Ohrid is strongly influenced by karstic springs, adjacent to large part of the coastline, sub-aquatic as well as surface springs which are particularly cool, clean and oxygen-rich inflowing water. The springs are fed by aquifers that are recharged from precipitation and, along the eastern shoreline, also by Lake Prespa.

The lake sediment covers a record of the last 1.5 million years. To better understand the link between the atmosphere and the sediment, our goal is to estimate the water turnover time of Lake Ohrid and to give an isotopic overview about the lake system. Our measured stable isotope data provide background information about hydrogen and oxygen isotope variability of the lake. The stable isotope results together with tritium data present a prospect for estimating evaporation and mixing proportions. The noble gas results detail the layers of the estimated mixing processes. Nitrogen stable isotope data provides additional information about the locality and the type of potential pollution sources.

How to cite: Túri, M., Temovski, M., Kiss, G. I., Csige, I., and Palcsu, L.: New estimation to the turnover time of Lake Ohrid: an environmental isotope and noble gas study, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-13702, https://doi.org/10.5194/egusphere-egu23-13702, 2023.

EGU23-13728 | Orals | HS2.2.7

Groundwater flow system as determined by multi-tracer approach in Tokyo Metropolitan area, Japan 

Maki Tsujimura, Kosuke Nagano, Keisuke Sato, Taiga Suzuki, and Hiroko Asakura

We performed an intensive monitoring and sampling of groundwater in Tokyo Metropolitan area to investigate the groundwater flow system from upland to lowland areas. We took 83 groundwater samples at 39 locations, 25 stream water samples, 7 spring water samples from August 2018 through June 2021. We also observed the spatial distribution of hydraulic head in the groundwater. The stable isotopic composition of oxygen 18 and deuterium, SF6 concentration, and solute ions concentrations were determined on all water samples.

The SF6 age of groundwater in the upland area ranges from a few years to 40 years, whereas that in the lowland area ranges from 40 years to more than 80 years. The solute concentrations are characterized by Ca-HCO3 type in the upland, whereas that is categorized in Na-HCO3 or Na-Cl type. In addition, d18O of the groundwater in the upland ranges from -10.4 per mil to -8.8 per mil, whereas that in the lowland ranges from -9 per mil to -8 per mil.

The hydraulic head distribution shows that the unconfined groundwater flows from west to east directions in parallel with the topographical surface, and the confined groundwater flows from south-west toward north-east directions in parallel with the bedrock surface topography.

The results show that the groundwater flows from west toward east directions across the border of the upland and the lowland, and it flows across the boundary of the aquifers, meaning the unconfined groundwater recharges the confined groundwater in an area where a certain amount of unconfined groundwater is pumped up.

How to cite: Tsujimura, M., Nagano, K., Sato, K., Suzuki, T., and Asakura, H.: Groundwater flow system as determined by multi-tracer approach in Tokyo Metropolitan area, Japan, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-13728, https://doi.org/10.5194/egusphere-egu23-13728, 2023.

EGU23-14005 | Posters on site | HS2.2.7

Quantifying changes in stream-landscape connectivity: combining high-resolution data of non-perennial streams and environmental tracers 

Jana von Freyberg, Izabela Bujak, Andrea Rinaldo, and Ilja van Meerveld

Changes in hydrologic connectivity between streams and the surrounding landscape are among the most important factors that control the temporal variation in streamwater chemistry. In most headwater catchments, the dynamic expansion and contraction of the non-perennial stream network affects and reflects this hydrologic connectivity. Until now, however, the spatiotemporal variations of non-perennial stream networks have been mapped only sporadically and environmental tracer data to explore the dynamic connectivity for these streams are lacking.

Within the TempAqua project, we have monitored the temporal variation in environmental tracers (solutes, stable water isotopes) in precipitation, soil- and groundwater, as well as in stream water during rainfall events in the pre-Alpine Erlenbach catchment. We combine these measurements with novel, sub-hourly data on stream network expansion and contraction.

Our data show that the total flowing stream length increased rapidly, up to 10-fold, during individual rainfall events. Changes in solute concentrations in streamwater indicate that different water stores become dynamically connected to the stream and disconnect again during subsequent dry periods: at the beginning of an event, the dilution of sulphate and calcium suggest a surface runoff contribution of rainwater at the time of rapid expansion of the network and increasing discharge. As rainfall continues, the stream network expands further due to rising groundwater tables, which is indicated by increased nitrate and sulphate concentrations in the stream. The magnitude and importance of these processes depends more on antecedent wetness conditions than event magnitude.

Our observations shed light onto the short-term mechanisms by which non-perennial streams start to flow during rainfall events, and provide new knowledge to address emerging questions on the functional relationships between stream-landscape connectivity, hydrological responses and water quality in headwater catchments, and their vulnerability to global climate change.

How to cite: von Freyberg, J., Bujak, I., Rinaldo, A., and van Meerveld, I.: Quantifying changes in stream-landscape connectivity: combining high-resolution data of non-perennial streams and environmental tracers, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-14005, https://doi.org/10.5194/egusphere-egu23-14005, 2023.

EGU23-14684 | Posters on site | HS2.2.7

Inferring the dynamics of StorAge Selection functions from GR4J 

Alban de Lavenne, Julien Tournebize, Hocine Henine, and Vazken Andréassian

Models based on StorAge Selection (SAS) functions are useful tools for understanding of factors controlling transit time distribution (TTD) and catchment-scale solute export. SAS functions describe the sampling of different ages in catchment storage that produces river discharge. This sampling may vary over time, for instance according to soil moisture:  the young water fraction is generally higher in wet conditions and lower in dry conditions. 

In this work, we investigated how the dynamic of this sampling could be related to the different fluxes and model states of the hydrological model GR4J. Different coupling strategies are tested over the French Orgeval catchment (ORACLE observatory, 104 km²) using chloride concentrations as a conservative tracer. The modelling results allowed to verify that the groundwater contribution, and in particular that outside the topographic catchment (intercatchment groundwater flow), strongly influences the age of the river flow. This study thus opens perspectives to better constrain the modelling of groundwater contribution to the river flow within the GR4J model.

How to cite: de Lavenne, A., Tournebize, J., Henine, H., and Andréassian, V.: Inferring the dynamics of StorAge Selection functions from GR4J, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-14684, https://doi.org/10.5194/egusphere-egu23-14684, 2023.

The Upper Jurassic aquifer (UJA) within the South German Molasse Basin (SGMB) is the most important exploration horizon for geothermal energy supply in Bavaria. The UJA shows a heterogeneous geology with karstic features and deep fault-zones. The result is a complex hydrogeology consisting of different groundwater types which differ significantly in their hydrochemical and isotopic composition.

Despite the great interest in the Upper Jurassic aquifer for geothermal energy supply, leading to numerous scientific studies, the exact apparent groundwater age, the infiltration area and the regional flow system remain yet unknown.

In this study we are using a multi parameter approach for the determination of apparent groundwater age distributions with the innovative 14CDOC and 81Kr methods and combine them with hydrochemistry data and stable water isotopes (δ18O/δ2H).

Our results indicate that the UJA system consists of at least two groundwater components: an up to now unknown young meteoric water component from the Pleistocene/Holocene transition and an older Pleistocene component. The apparent 14CDOC ages increase from south to north and show some evidence that the infiltration area of the UJA is located in the southern part of the SGMB and a groundwater flow directed to the north.

How to cite: Winter, T. and Einsiedl, F.: Characterisation of the regional groundwater flow system in the South German Molasse Basin using apparent groundwater age distributions with 14CDOC and 81Kr, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-15240, https://doi.org/10.5194/egusphere-egu23-15240, 2023.

Diurnal fluctuations of hydrological processes, such as discharge and groundwater level, and of in-stream concentrations of various solutes have been observed in many catchments. The timing of minima and maxima of hydrometric and hydrochemical parameters during the 24 hour cycle can be used to elucidate the baseflow dynamics of catchment hydrological processes and of the mobilization of solutes into streams. In general, diurnal fluctuations of discharge and in-stream solute concentrations have been related to effects of evapotranspiration, temperature-controlled viscosity changes of water, freeze-thaw cycles and a temperature-dependent increase of biological activity during the day. The aim of this study was to better understand the seasonal and topography-driven release of dissolved organic carbon (DOC) during inter-event periods in a small forested headwater catchment within the Bavarian Forest National Park (Germany). We analyzed DOC concentrations and DOC absorbance metrics (as an indicator for DOC quality characteristics) at three topographically different positions of the headwater stream in high frequency by means of in-situ UV-Vis spectrometry over the period of two years. Our data show distinct seasonal differences in the amplitude of diurnal fluctuations of discharge as well as DOC concentrations that are accompanied by clear differences in DOC absorbance characteristics. The timing of diurnal minima and maxima of discharge and DOC concentrations changes over the seasons and along the stream. We present a comprehensive analysis of diurnal fluctuations of discharge, DOC concentrations and DOC quality metrics as influenced by season and topographical position and relate this to findings from other research studies. Disentangling the patterns and dynamics of diurnal variations of hydrological and biogeochemical variables is crucial for fully understanding catchment functioning and the export of carbon from terrestrial catchments as one component of the global carbon budget, particularly because extended drought (i.e., baseflow) periods are forecast to occur more often as a consequence of climate change.

How to cite: Hopp, L. and Blaurock, K.: Seasonal dynamics of diurnal fluctuations of in-stream dissolved organic carbon concentrations and quality metrics in a forested headwater catchment, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-15253, https://doi.org/10.5194/egusphere-egu23-15253, 2023.

EGU23-15677 | ECS | Orals | HS2.2.7

Architecture of seepage zones combined with their residence time to constrain hydrogeological models 

Ronan Abhervé, Clément Roques, Eliot Chatton, Laurent Servière, Jean-Raynald de Dreuzy, and Luc Aquilina

Hydrological predictions for ungauged basins at catchment and regional scales are still challenged by the lack of available data. Under the assumption that the perennial stream network is mostly fed by groundwaters, its spatial extent is controlled by the magnitude of the subsurface hydraulic conductivity (K) with respect to the actual recharge rate (R). In addition, the residence time of groundwater is directly controlled by the storage capacity of the aquifer system, i.e. the porosity (Ө). Here we propose a new inversion approach that jointly considers the spatial organization of observed hydrographic network and the residence times of groundwater measured at springs to infer the geometry of the aquifer system and its hydraulic properties.

We used a dataset gathered in an alpine catchment observatory (Natural conservation area of the Massif of Saint-Barthélemy, Pyrenees, France). The extent of the stream network has been mapped using field observation. Residence times have been obtained from concentrations of dissolved CFCs and SF6 gases measured at 6 spring locations distributed over the catchment. The average transit time is about 30 years for perennial springs with a significant variability across the watershed. The relatively high residence time is also confirmed by high Helium concentrations.

In our inversion scheme, we evaluate the accuracy of an ensemble of 3D hydrogeological models with different aquifer geometries and hydraulic properties. We found that topography and aquifer compartmentalization, through the decreasing trend in hydraulic conductivity, are key parameters in setting the spatial pattern of seepage areas and the distribution of transit times across the catchment. In addition, by running transient simulations of the model ensemble we further explore the accuracy of the models by comparing results with measurements of stream discharge and the intermittency of the hydrographic network. We found that intermittence seems to be connected to high transmissive shallow flow structures with low storage capacities (mostly organized within shallow soils and rockslides). However, perennial springs are sustained by deep groundwater flow paths within the bedrock. In perspective, we discuss the potential evolution of the extent, discharge magnitude and the transit time of seeping groundwater under changing recharge scenarios.

How to cite: Abhervé, R., Roques, C., Chatton, E., Servière, L., de Dreuzy, J.-R., and Aquilina, L.: Architecture of seepage zones combined with their residence time to constrain hydrogeological models, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-15677, https://doi.org/10.5194/egusphere-egu23-15677, 2023.

Current methods for tracing the surface infiltration of meteoric groundwaters rely on isotope geochemistry and dye tracers, which can be used to determine groundwater age and altitude at the point of infiltration. Temporal and spatial variability in atmospheric conditions, and water-rock interactions, can make the interpretation of isotopes uncertain. Low tracer recovery and long residence times often make dye tracers impractical. Here, we propose a new method of groundwater tracing based on fingerprinting of natural dissolved organics (derived from local flora and fauna). We validate our method at the Grimsel Test and Mont Terri underground rock laboratories in Switzerland, located within fractured crystalline rock (granite) and sedimentary systems, respectively. Based on a non-targeted approach using two-dimensional gas chromatography, we derive detailed organic fingerprints for groundwater, surface soils, and lakewater and river water samples from each location. These organic fingerprints are then compared to determine the near-surface infiltration environments feeding individual groundwater samples. Using principal component analysis, we show that individual groundwater samples can be identified as having derived from identifiable surface sources. Our research demonstrates that dissolved natural organic molecules, and their relative abundance, are sufficiently well-preserved in groundwater over timescales of several decades, that they can be used to discriminate the near-surface environment(s) through which meteoric groundwater has infiltrated. Organic fingerprinting could prove a powerful tool for an improved understanding of groundwater flow systems, particularly when used in combination with other complimentary tracing techniques.

How to cite: Stillings, M., Lunn, R., and Shipton, Z.: Fingerprinting dissolved organic compounds: A potential tool for identifying the surface infiltration environments of meteoric groundwaters, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-16229, https://doi.org/10.5194/egusphere-egu23-16229, 2023.

During prolonged drought periods surface water contributions via bank filtration to drinking water production sites located on alluvial aquifers can become increasingly relevant due to associated changes in the hydraulic boundary conditions. Considering the predicted increase of occurance probabilities for hot and dry summers in the humid climate zone, these sites might be prone to an increased risk related to anthropogenic emissions into the connected surface water bodies in the near future.

We studied these processes at two well fields (8 active wells in total) located on the alluvial aquifer of the river Kyll, Germany, about 1 km downstream of the community of Kordel and the city´s waste water treatment plant. For six months we sampled bi-weekly water quality parameters in the wells (horizontal distances to the river varied between 30 and 420 m) and at three locations at the river Kyll. Samples were analyzed for stable water isotopes, EC, pH, DO, DOC, major ions, metals and selected pharmaceutical products. Based on a mixing analysis using major ion data we quantified the mean surface water contribution for each well, varying between 40 and 95 %. Using a darcian modelling approach based on continuous pumping rates, hydraulic gradients, existing information on hydraulic conductivities and the possible geometric connectivity of each of the wells to the river we were able to infer potential residence time distributions for the estimated surface water contributions for each of the wells. Comparing these distributions with nutrient gradients and oxic conditions we find significant correlations with the 0.05 quantile shortest residence time estimations, only. Resulting residence times of surface water contributions within the alluvial aquifer range from several days to weeks instead of previously estimated months to years. Dynamics in stable water isotope patterns in rainfall, surface water and groundwater show as well changes in surface water and groundwater composition within two weeks following the changes in the rainfall isotopic composition. Contrary to nutrient dynamics, the trace organic compounds, i. e. pharmaceutical products did not show spatial or temporal patterns, but a constant, substance specific degradation which leads to the conclusion that trace organic compound retention occurs in the nutrient rich near proximity of the river bed, i.e. the hyporheic zone.

These results demonstrate how quantitative and qualitative surface water contributions to groundwater / drinking water wells can have an increased relevance under drought conditions than previously anticipated.

How to cite: Schuetz, T. and Förster, A.: Infering the relevance of bank filtration processes for drinking water production sites on alluvial aquifers under drought conditions using residence time distributions and water quality parameters, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-16851, https://doi.org/10.5194/egusphere-egu23-16851, 2023.

HS2.3 – Water quality at the catchment scale

EGU23-276 | ECS | Orals | HS2.3.1 | Highlight

Wildfire impacts on water: improving impact assessment though model adaptation 

Marta Basso, Jacob Keizer, Dalila Serpa, Marcos Mateus, and Diana Vieira

Wildfires are a threat to water security worldwide, due to the negative effect of the post-fire mobilization of sediments and associated nutrients and contaminants on the waterbodies located downstream of burned areas. Such impacts have been assessed in field studies and, more recently, also through modelling approaches. Models are valuable tools for anticipating the potential negative impacts of wildfires, allowing to test different environmental scenarios. The state of the art in post-fire model adaptation has shown that most studies simulate the hydrological and erosion response in the first post-fire year in situ, without considering the cascading effects on downstream waterbodies. In addition, few studies have evaluated the long-term impacts of wildfires, likely due to the limited available data. Among the existing gaps in post-fire modelling, ash transport has recently been identified as a priority. The lack of ash modelling studies has been ascribed to the limited understanding of ash behavior and the difficulties of incorporating ash-related processes into the structure of existing models.

As a way to fulfill these research gaps and advance the state of the art in post-fire hydrological modeling, the authors provided several contributions in recent years.

For instance, a watershed model has been coupled with a reservoir model to simulate the effects of fires on drinking water supplies, using the outputs of the main streams as inputs to the reservoir branches. As most simulations commonly end at the watershed outlet, a simple methodology was proposed to assess how the impacts on watercourses propagate to the drinking water supply inlet. The results showed that integrated modeling frameworks are critical for anticipating the off-site impacts of fires.

Post-fire management can also influence the impacts of fires beyond the first post-fire rainfall events, when the soil is exposed and ash and sediment transport is greatest. Another modelling exercise evaluates the long-term impacts of different post-fire management options, more specifically terracing, mulching and natural recovery, on water availability and quality.

As post-fire ash and sediment mobilization is typically limited to the duration of the rainfall events, which typically lasts for a few hours, hydrological models that run at a daily time-step can underestimate the environmental impacts of fires. To improve the knowledge of post-fire hydrological processes at event-based scale, two hydrological models (LISEM and MOHID) were calibrated, accounting for burn severity and initial soil moisture conditions before each specific rainfall event.

The work done in the past years is expected to be of added value for the post-fire modeling community, providing future directions on post-fire hydrological modelling studies.

 

How to cite: Basso, M., Keizer, J., Serpa, D., Mateus, M., and Vieira, D.: Wildfire impacts on water: improving impact assessment though model adaptation, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-276, https://doi.org/10.5194/egusphere-egu23-276, 2023.

EGU23-572 | ECS | Orals | HS2.3.1

Post-fire water contamination risk assessment in Portugal 

Niels Nitzsche, Joost Schuurman, Luís Dias, João Pedro Nunes, and Joana Parente

Wildfires in the Mediterranean basin, especially in Portugal, have increased in extent and frequency over the last few years. One of the many impacts of wildfires on humans and ecosystems is on the water quality of surface waters. Ashes and increased erosion rates might elevate the influx of nutrients, sediments, or other water quality-related components, possibly affecting the water supply. This study has three main objectives. (1) Identifying post-fire water contamination events in over 60 Portuguese reservoirs, through changepoint analysis of historical time series for (2) Testing the relationship between post-fire water contamination events with fire-, watershed-, reservoir-, and climatic drivers through logistic regression using generalized additive models. (3) The modelling and evaluation of post-fire water supply contamination risks in Portugal, using a deterministic approach. Results showed increases in TSS in 13.6% of all wildfires. Most changes fell into the unusually large fire seasons of 2003-2005 and 2017, while the most significant impacts could be seen in southern reservoirs after 2005. Fire size was identified as the main driver of post-fire water contamination, while reservoir and climate-related characteristics like water levels also played a significant role in TSS. Increased levels of suspended sediments were identified as a potential threat to the water supply, especially when large wildfires coincide with drought-induced low reservoir water levels. The modelling of past water contamination episodes shows a similar spatial distribution as the structural fire risk in Portugal, identifying the centre (and southern) regions as the most affected areas. This study may support numerous case and modelling studies and inform water managers about possible future threats.

How to cite: Nitzsche, N., Schuurman, J., Dias, L., Nunes, J. P., and Parente, J.: Post-fire water contamination risk assessment in Portugal, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-572, https://doi.org/10.5194/egusphere-egu23-572, 2023.

EGU23-1074 | ECS | Orals | HS2.3.1

Comparing Critical Source Areas for the Sediment and Nutrients of Calibrated and Uncalibrated Models in a Plateau Watershed in Southwest China 

Meijun Chen, Annette B. G. Janssen, Jeroen J. M. de Klein, Xinzhong Du, Qiuliang Lei, Ying Li, Tianpeng Zhang, Wei Pei, Carolien Kroeze, and Hongbin Liu

Controlling non-point source pollution is often difficult and costly. Therefore, focusing on areas that contribute the most, so-called critical source areas (CSAs), can have economic and ecological benefits. CSAs are often determined using a modelling approach, yet it has proved difficult to calibrate the models in regions with limited data availability. Since identifying CSAs is based on the relative contributions of sub-basins to the total load, it has been suggested that uncalibrated models could be used to identify CSAs to overcome data scarcity issues. Here, we use the SWAT model to study the extent to which an uncalibrated model can be applied to determine CSAs. We classify and rank sub-basins to identify CSAs for sediment, total nitrogen (TN), and total phosphorus (TP) in the Fengyu River Watershed (China) with and without model calibration. The results show high similarity (81%-93%) between the identified sediment and TP CSA number and locations before and after calibration both on the yearly and seasonal scale. For TN alone, the results show moderate similarity on the yearly scale (73%). This may be because, in our study area, TN is determined more by groundwater flow after calibration than by surface water flow. We conclude that CSA identification with the uncalibrated model for TP is always good because its CSA number and locations changed least, and for sediment, it is generally satisfactory. The use of the uncalibrated model for TN is acceptable, as its CSA locations did not change after calibration; however, the TN CSA number decreased by around 60% compared to the figures before calibration on both yearly and seasonal scales. Therefore, we advise using an uncalibrated model to identify CSAs for TN only if water yield composition changes are expected to be limited. This study shows that CSAs can be identified based on relative loading estimates with uncalibrated models in data-deficient regions.

How to cite: Chen, M., Janssen, A. B. G., de Klein, J. J. M., Du, X., Lei, Q., Li, Y., Zhang, T., Pei, W., Kroeze, C., and Liu, H.: Comparing Critical Source Areas for the Sediment and Nutrients of Calibrated and Uncalibrated Models in a Plateau Watershed in Southwest China, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-1074, https://doi.org/10.5194/egusphere-egu23-1074, 2023.

EGU23-2101 | ECS | Posters on site | HS2.3.1

Drinking water quality research of the soum centers and settled areas in south Gobi of Mongolia 

Altantungalag Danzan, Uuganbayar Purevsuren, and Gan-Erdene Dorjgotov

Groundwater is vital resource for both the local people and livestock of the Gobi region of Southern Mongolia where surface water distribution is limited. Apparently, whether the water is suitable for drinking purpose is significant issue to study. The purpose of this study is to assess the quality of water in local water supply wells and to identify  hydrochemical facies and origin of the micro elements of the water. In the study, totally 233 water samples were collected from the existing water wells located in 77 soum centers and settled areas of 10 provinces of southern Mongolia. The water samples were analyzed at the Central Geological Laboratory in Ulaanbaatar. Major cations (K+, Na+, Ca2+, Mg2+, SiO2) and anions (Cl-, HCO3-, SO4-, NO2-, NO3-, F-) were determined. In addition, total 12 trace metals (Be, B, Cr, Mn, Cu, As, Se, Sr, Mo, Cd, Ba, U) have been determined by the ICP-124. As a result, the groundwater of the target region is identified to be alkaline and as for the mineralization, it refers to fresh or brakishwater type. Hydrochemical facies are identified to be the types of Ca-HCO3, NaCl, Ca-Na-HCO3 and Ca-Mg-Cl. Moreover, the sources of major ions of the groundwater in the region is characterized by more dominance of water and rock unit interaction and less impact of recharge and evaporation. When compared to drinking water standard, the hardness, Na ion and Mg ion exceed the maximum allowable limits in the water samples taken from water wells of 28 soums, 24 soums and 47 soums, respectively. The concentration of arsenic was higher than drinking water standards of World Health Organization (WHO) in 21 soums of the study area and other metals including uranium, strontium and selenium in water exceeded drinking water standards in 9 soums centers water supply wells.

How to cite: Danzan, A., Purevsuren, U., and Dorjgotov, G.-E.: Drinking water quality research of the soum centers and settled areas in south Gobi of Mongolia, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-2101, https://doi.org/10.5194/egusphere-egu23-2101, 2023.

EGU23-2206 | Orals | HS2.3.1

A novel machine learning national model for diffuse source total phosphorus concentrations in streams 

Brian Kronvang, Jørgen Windolf, Henrik Tornberg, Jonas Rolighed, and Søren Larsen

Data on the diffuse source annual flow weighted total phosphorus (TP) concentrations from 349 Danish streams draining smaller catchments (< 50 km2) for the period 1990-2019 were used for developing a model in machine learning software (DataRobot version 6.2; DataRobot Inc. Boston MA, USA). The developed diffuse source TP-concentration model will substitute an older model that have been in place to calculate P-loadings to Danish estuaries from ungauged areas. A total of 207 streams with 3,144 annual observations of flow-weighted TP concentrations together with information on 19 explanatory variables was entered into the DataRobot software. DataRobot divides the input data into three layers: Training dataset (64%), validation dataset (16%) and hold out dataset (20%). Thereafter, DataRobot conducts a five-layer cross-validation and tests among 72 different model types before suggesting final best solutions.

In this case, the TP-concentration model was developed as an ‘eXtreme Gradient Boosted Trees Regressor with early stopping’ as suggested by the DataRobot software to be superior for modelling the annual flow-weighted TP concentration based on 13 explanatory variables. The most influencing explanatory variables in the final model are: 1) tile drainage in the catchments; 2) ; 3) period (two periods with different sampling regimes; 4) proportion of agricultural land; 5) importance of bank erosion; 6) deviation of annual runoff from long-term mean. The final TP-concentration model has a R2=0.69 for the training dataset, R2 = 0.71 for the validation dataset and R2 = 0.67 for the hold out dataset.

A validation of the new machine learning TP-concentration model on 142 independent streams with 1,261 annual observations was conducted to investigate the uncertainty of the model simulations. The validation showed the TP-concentration model to have a high explanatory power (R2=0.60) and with a very good simulation performance in the nine Danish georegions, as well as for the 30 year long time series of data. 

An application of the model for calculating flow-weighted TP-concentrations within nearly 3,200 catchment polygons (ID15’s) covering the Danish land area showed that the new developed machine learning TP-model is a valuable tool both for calculation of TP-loadings from ungauged areas to lakes and coastal waters as well as for linking catchment pressures to stream ecological status.   

How to cite: Kronvang, B., Windolf, J., Tornberg, H., Rolighed, J., and Larsen, S.: A novel machine learning national model for diffuse source total phosphorus concentrations in streams, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-2206, https://doi.org/10.5194/egusphere-egu23-2206, 2023.

EGU23-2722 | ECS | Posters on site | HS2.3.1

Influence of sanitary infrastructure on nutrient transport mechanisms in a headwater catchment 

Caroline Spill, Lukas Ditzel, and Matthias Gassmann

Sanitary infrastructures draining smaller villages are often not taken specifically into account when discussing catchment transport process. One reason is the limited data availability, as they are usually not part of (high frequency) monitoring strategies, although it has been shown, that they can have a significant impact on water quantity and quality. Especially in first- or second-order streams, they can contribute a big share to the discharge volumes. At the same time, the dilution effect of small streams is limited. This is critical, as e.g. wastewater treatment plants (WWTPs) often have to meet lower requirements compared to their bigger counterparts treating water from cities, meaning, that especially nutrient concentrations can be still high in the effluent.

We measured discharge and different water quality data in a headwater stream (2.77 km²), which is influenced by agriculture, a small village and point sources: two combined sewer overflows (CSOs) and one WWTP. In comparison to other studies, we decided to implement our measurements shortly after the point sources, to measure the nutrient signal with little influence of in-stream processes.

The WWTP always contributed a high share of water, especially during dry periods. However, the discharge from the WWTP was much higher, than one would expect based on the number of inhabitants. Water quality data from the WWTP suggest, that groundwater is infiltrating into the sewer system and is additionally treated within the WWTP. This could also explain the high number of CSO events: infiltrating groundwater leads to the exceedance of the sewer system design capacities even at medium-sized rainfall events. As a consequence, not only CSO events occur more often, but also cleaning processes within the WWTP seem to be interrupted, explaining the increasing ammonium and ortho-phosphorus concentrations during events. Especially during long-lasting events with several peaks, the hysteresis analysis shows the activation of different nutrient sources, indicating a complex interaction between the sanitary infrastructure and the catchment itself.

Our data shows, that even small point sources from villages can have a significant influence on water quantity and quality. Similar to agricultural or natural catchments, their individual influence varies depending on season and pre-event conditions and are not constant throughout the year.

How to cite: Spill, C., Ditzel, L., and Gassmann, M.: Influence of sanitary infrastructure on nutrient transport mechanisms in a headwater catchment, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-2722, https://doi.org/10.5194/egusphere-egu23-2722, 2023.

EGU23-2990 | Posters on site | HS2.3.1

Developing the real-time water quality program using machine learning and API. 

Gihun Bang, Na-Hyeon Gwon, Min-Jeong Cho, Ji-Ye Park, and Sang-Soo Baek

The importance of water quality monitoring (e.g., TOC, DO, Chl-a, TN, and TP) is increasing in part of agriculture, water treatment, and policy decision. As the computing power has been increased, we could develop the real-time water quality system. Our system can forecast the water quality after 2 days from now. To simulate the water quality of ND river, the random forest (RF) and artificial neural network (ANN) were adopted. Furthermore, the program provides a user-friendly system using a graphic user interface (GUI). Our prediction program consists of 3 major phases. Phase 1 utilizes an application programming interface (API) to load the data from national institutes (NI). Phase 2 is the simulation of flowrate of ND River. Phase 3 simulates the water quality using machine learning. RF models produced R2 values of 0.46, 0.8, 0.59, 0.46, 0.67 for chl-a, DO, TN, TOC, and TP respectively while ANN models resulted in R2 values of 0.22, 0.72, 0.53, 0.35, 0.63. Overall, DO shows the most accurate result while TN and TP showed reasonable simulation results, by showing over 0.5 of R2. Our study demonstrates that API service with machine learning is useful for simulating real-time water quality.

How to cite: Bang, G., Gwon, N.-H., Cho, M.-J., Park, J.-Y., and Baek, S.-S.: Developing the real-time water quality program using machine learning and API., EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-2990, https://doi.org/10.5194/egusphere-egu23-2990, 2023.

Intensive livestock production has raised enormous water quality concerns in Europe and elsewhere around the world. There is a need to examine long-term water quality trends and understand the drivers for the trends based on detailed catchment monitoring. Given orthophosphate-phosphorus (P) is highly relevant to eutrophication in freshwater lakes and rivers, we monitored its concentration and load trends in streamwater of a livestock-intensive catchment in western Norway for a 20-year period, using the approaches of continuous flow measurements and flow-proportional composite water sampling. Precipitation and catchment-level soil P balance, as well as field-level measurements of soil P status, were monitored to examine the drivers. Trend analyses showed that both annual mean P concentration (range: 0.05–0.14 mg L-1; mean: 0.08 mg L-1; p = 0.001) and annual P load (range: 0.35–1.46 kg ha-1; mean: 0.65 kg ha-1; p = 0.0003) increased significantly over the 20-year monitoring period. The mean concentrations were positively correlated with cumulative soil P surplus (R2 = 0.55, p = 0.0002). Although discharge of the streamflow significantly affected annual P load, the P surplus appeared to be an even more important factors. The study highlights that long-term P surplus plays a critical role in influencing orthophosphate-P concentration and loads in livestock-intensive regions. There is a big challenge to reduce the P surplus, which however may be achieved through integrated strategies such as reducing livestock density, manure refinement and transport to crop-intensive regions, improving livestock feeding management, and increasing crop P removal.

How to cite: Liu, J., Bechmann, M., and Øgaard, A. F.: Water quality trends and the drivers in livestock-intensive regions: Results from 20 years of catchment monitoring in Norway, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-3176, https://doi.org/10.5194/egusphere-egu23-3176, 2023.

EGU23-3184 | ECS | Orals | HS2.3.1

Shedding light on the organic matter black box: Using fluorescence spectroscopy to understanding microbial sources and pathways TLF 

Natasha Harris, Gareth Old, Mike Bowes, Peter Scarlet, David Nicholls, Linda Armstrong, Daniel Read, Ben Marchant, and James Sorensen

The river Thames catchment  passes through rural and urban centres covering many different environments and land uses. Therefore, it is exposed to a range of stresses from sewage pollution to run off from agriculture. As such, UKCEH has been conducting water quality monitoring of the Thames since 1997, which later expanded into the Thames Initiative. The Thames Initiative collects a wide range of chemical and biological data, at 19 sites across the Upper Thames Catchment and its tributaries. For 18 months, in 2012-13, fluorescence spectroscopy and PARAFAC analysis was used to identify 4 components of fluorescent organic matter (FOM). This research focusses on the role of the fourth component, C4, which represents a tryptophan like FOM(TLF). The study is looking at the peak’s temporal variability at all 19 sites within the Thames catchment, alongside nutrient and biological data. This will enable greater understanding TLF’s sources and pathways by analysing TLF’s interaction with other nutrients and pollutants.  There is robust research linking TLF to sewerage pollution and more widely anthropogenic activity. However, the understanding of TLF as a product of insitu production from microorganisms is still in relative infancy, particularly when looking for evidence in the field at a catchment level. In this study multiple variate linear modelling using forward stepwise regression techniques have been applied to the data at each site to investigate the sources of C4 across the catchment to understand both catchment and instream processes. The possible predictors available to each model were dissolved potassium (DK), total dissolved nitrogen (TDN), dissolved calcium (DCa), total bacterial counts(TBC) and chlorophyll a. The models used between 2-3 predictors (σ=2.53, μ =0.678). DK was the most common (18 models),  followed by TBC (11 models), then DCa and TDN (both 8 models) and finally chlorophyll a (2 Models). These results suggest a dominant source of C4 across the catchment is from the wastewater as dissolved potassium is a sewerage indicator.  Secondly the occurrence of TDN or dissolved  calcium suggest a more dominate baseflow path of the fluorescence at these sites, as found in previous analysis of these sites.  However, most novelty is the regular occurrence of TBC in the models. This suggests  the C4 component has a bacteriological element as well, which means it is likely there is an important contribution of TLF by insitu-production from microorganisms.

How to cite: Harris, N., Old, G., Bowes, M., Scarlet, P., Nicholls, D., Armstrong, L., Read, D., Marchant, B., and Sorensen, J.: Shedding light on the organic matter black box: Using fluorescence spectroscopy to understanding microbial sources and pathways TLF, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-3184, https://doi.org/10.5194/egusphere-egu23-3184, 2023.

EGU23-3930 | ECS | Posters on site | HS2.3.1

How much did the Nitrates Directive contribute to changes in surface water nitrate concentrations across German catchments? 

Tam Nguyen, Rohini Kumar, Pia Ebeling, Fanny Sarrazin, Andreas Musolff, and Jan Fleckenstein

Nitrate originating from agricultural lands is identified as one of the main causes of water pollution in Europe. As a result, the European Nitrates Directive (ND) was introduced in 1991 to protect water bodies from nitrate pollution by reducing diffuse nitrogen inputs. Despite decades having passed since its implementation, there are diverging observations of nitrate concentration changes in surface waters in Europe. Recent work suggested that the success of input reduction can be strongly blurred due to long water and nitrogen transit times and the built-up of nitrogen stores in catchment soils, making it difficult to evaluate the effectiveness of the ND. Therefore, it is still unclear to what extent the ND contributed to changes in surface water nitrate concentrations.  Such understanding could help to develop better management policies. In this study, we used previously calibrated nitrate export models for various German catchments (Nguyen et al., 2022) based on the principle of water transit times and observed inputs (baseline scenario). We then force these models with different N input trajectories that assume no implementation of the ND (hypothetical scenarios). Here, we will compare simulation results from the baseline scenario with hypothetical scenarios to evaluate the effectiveness of the ND implementation as well as its controlling factors. In addition, we will also check if different catchments respond differently to changes in N inputs to see whether different management strategies are needed for different catchments.

Nguyen, T. V., Sarrazin, F. J., Ebeling, P., Musolff, A., Fleckenstein, J. H., & Kumar, R. (2022). Toward understanding of long-term nitrogen transport and retention dynamics across German catchments. Geophysical Research Letters, 49, e2022GL100278. https://doi.org/10.1029/2022GL100278

How to cite: Nguyen, T., Kumar, R., Ebeling, P., Sarrazin, F., Musolff, A., and Fleckenstein, J.: How much did the Nitrates Directive contribute to changes in surface water nitrate concentrations across German catchments?, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-3930, https://doi.org/10.5194/egusphere-egu23-3930, 2023.

EGU23-4144 | ECS | Posters on site | HS2.3.1

Long-term dynamics of nitrogen export from European catchments 

Fanny Sarrazin, Tam Nguyen, Andreas Musolff, Pia Ebeling, Masooma Batool, Paromita Sarker, Yevheniia Anpilova, Jan Fleckenstein, Sabine Attinger, and Rohini Kumar

Since the beginning of the twentieth century, anthropogenic activities have severely altered the global nitrogen (N) cycle through the fixation of atmospheric N for the production of N fertilizers, the cultivation of N fixing crops, fossil fuel combustion, and the discharge of human and industrial wastewater into the environment. Both N diffuse sources (fertilizer application, biological N fixation and atmospheric N deposition) and point sources (wastewater) have led to the contamination and eutrophication of numerous water bodies worldwide and are still threatening human and aquatic ecosystem health today. This calls for both large-scale and long-term analyses of N dynamics to gain a better understanding of the changes in N export from streams in response to changes in N input following environmental policies and technological developments.

In this study, we investigate the long-term dynamics of N export from European river basins over the last 70 years, which is made possible by our recent development of novel gridded datasets of long-term N diffuse sources and point sources across Europe (Batool et al., 2022). To this end, we apply the mHM hydrological model coupled with the SAS-N model (Nguyen et al., 2022). The latter accounts for possible N accumulation in the soil (biogeochemical legacy), as well as in the subsurface (hydrological legacy) utilizing water travel time via StorAge Selection (SAS) functions. We quantify N export in major European river basins (e.g. Danube, Elbe, Rhine, Rhone, Seine) accounting for the uncertainties in input data and model parameters (Sarrazin et al., 2022). We identify distinct relationships between N inputs and simulated N export, resulting from different legacy behaviours across river basins. Overall, we find a decreasing contribution of point sources to total N export over the study period, due to improvements in wastewater treatment. Through learning from the past N export dynamics, our study ultimately contributes to informing the development of future management strategies to reduce N levels below target values.

Batool, M., Sarrazin, F. J., Attinger, S., Basu, N. B., Van Meter, K., & Kumar, R. (2022). Long-term annual soil nitrogen surplus across Europe (1850–2019). Sci. Data, 9, 612. https://doi.org/10.1038/s41597-022-01693-9

Nguyen, T. V., Sarrazin, F. J., Ebeling, P., Musolff, A., Fleckenstein, J. H., & Kumar, R. (2022). Toward understanding of long-term nitrogen transport and retention dynamics across German catchments. Geophys. Res. Lett., 49, e2022GL100278. https://doi.org/10.1029/2022GL100278

Sarrazin, F. J., Kumar, R., Basu, N. B., Musolff, A., Weber, M., Van Meter, K. J., & Attinger, S. (2022). Characterizing catchment-scale nitrogen legacies and constraining their uncertainties. Water Resour. Res., 58, e2021WR031587. https://doi.org/10.1029/2021WR031587

How to cite: Sarrazin, F., Nguyen, T., Musolff, A., Ebeling, P., Batool, M., Sarker, P., Anpilova, Y., Fleckenstein, J., Attinger, S., and Kumar, R.: Long-term dynamics of nitrogen export from European catchments, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-4144, https://doi.org/10.5194/egusphere-egu23-4144, 2023.

EGU23-4639 | Posters on site | HS2.3.1

Occurrence of Dissolved Organic Nitrogen (DON) in Low-relief Streams on the Eastern Shore of Virginia, USA 

Janet Herman, Benjamin Burruss, and Aaron Mills

The agricultural use of nitrogenous fertilizer in watersheds along the Atlantic Coast, USA, has fueled concerns and investigations into the upland-derived nitrate (NO3­-) discharging to coastal waters.  Past studies of low-relief, gaining streams in small watersheds on the Eastern Shore of Virginia, USA, have quantified the NO3-­-N flux to seaside lagoons and the Atlantic Ocean.  The contribution of dissolved organic nitrogen (DON) to the total nitrogen loading to coastal waters had not previously been evaluated.  This study quantified concentrations of DON, NO3­-, and total dissolved nitrogen (TDN) under baseflow conditions in 15 streams varying in watershed size and cropland use on the Eastern Shore of Virginia across a one-year period.  Mean concentrations of DON in streams ranged from 0.328 to 2.14 mg N L-1 and represented 12 to 70% of the TDN pool.  In 14 of the 15 streams, NO3- was the principal form of nitrogen ranging in mean concentrations from 0.094 to 6.06 mg N L­-1.  Instream DON concentrations were independent of NO3- concentrations, watershed area, and cropland use.  Unlike NO3-, DON varied seasonally with highest DON concentrations observed in spring.  DON ranged from 6 to 41% of the TDN in shallow groundwater with concentrations from 0.776 to 2.12 mg N L-1.  These concentrations were lower than the respective concentrations determined in overlying surface-water samples (0.001 to 0.773 mg N L-1) collected concurrently.  In a laboratory experiment, DON of 1.02 mg N L-1 was eluted in the effluent from an intact streambed sediment core using artificial groundwater influent containing NO3- only and represented nearly 60% of the TDN in the core effluent.  The results of this study establish DON as an important and dynamic constituent of the TDN pool in freshwater streams discharging from the Eastern Shore of Virginia, USA, to the coastal waters of the Atlantic Ocean.

How to cite: Herman, J., Burruss, B., and Mills, A.: Occurrence of Dissolved Organic Nitrogen (DON) in Low-relief Streams on the Eastern Shore of Virginia, USA, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-4639, https://doi.org/10.5194/egusphere-egu23-4639, 2023.

EGU23-4869 | Posters on site | HS2.3.1

Variation of dissolved phosphorus in groundwater of riparian zones in an agricultural area 

Dong-Chan Koh and Hong-Il Kwon

Phosphorus, which is one of important factors of surface water eutrophication, has been the main issue in surface water quality management. In recent years, there has been an increasing interest in phosphorus in groundwater as well as surface water. Increasing number of studies has reported groundwater with high concentrations of phosphorus and its effect on adjacent surface water. The multi-level monitoring wells were installed in riparian zones of an agricultural area to demonstrate processes of phosphorus in groundwater. A stream in the area is largely in gaining condition, but losing condition was found in the area with extensive groundwater pumping. In this study, the processes of increasing and decreasing phosphorus concentration in groundwater under anaerobic conditions were examined with redox sensitive species. The dominant redox processes in groundwater were identified using redox sensitive parameters, which varied from oxic to sulfate reduction. Phosphorus concentrations were low in oxic and denitrification dominant condition and high in iron reducing dominant condition. This result was consistent with many recent studies. It is expected that phosphorus concentrations were reduced by precipitation of secondary iron minerals in the aerobic condition and increased by dissolution of the secondary minerals in the anaerobic condition. However, phosphorus concentration in the groundwater tended to attenuate under the more reducing condition than iron-reducing dominant condition. In this study, we tried to interpret dissolved phosphorus concentration in relation to the redox sensitive species and to understand the attenuation processes of dissolved phosphorus under strongly reducing conditions.

How to cite: Koh, D.-C. and Kwon, H.-I.: Variation of dissolved phosphorus in groundwater of riparian zones in an agricultural area, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-4869, https://doi.org/10.5194/egusphere-egu23-4869, 2023.

EGU23-4890 | ECS | Orals | HS2.3.1

Can we trust our data sources? A case study presenting limits of spatial detail of sediment transport modelling 

Miroslav Bauer, Tomas Dostal, Josef Krasa, John Schwartz, and Karina Bynum

The paper discusses the limits of data sources that are widely available, used and applicable for soil erosion and sediment transport modelling. It emphasizes the accuracy and spatial detail of land use and stream topology data. These two inputs are critical in terms of sediment transport dynamics. The aim of the paper is to point out the error propagation into results at the small catchment scale if the data is used inappropriately. In contrast, we show how the quality and accuracy can be significantly improved by checking, verifying and modifying the directly available data sources to make them applicable at the scale of smaller catchment (tens of km2). The accuracy that can be achieved by directly measuring and describing the real situation in the field (land use, streams, crops) is discussed.

WaTEM/SEDEM (based on RUSLE and sediment transport capacity assessment) was selected as a modelling approach. The results will be interpreted using a case-study of the Oostanaula watershed, Tennessee, USA, approximately 10km2. Modelling utilized the most recent available DEM, land use and soil data in raster resolution 10x10 m.

Research has been supported by project TUDI (European Union's Horizon 2020 research and innovation programme under grant agreement No 101000224), LTA-USA 19019 (Ministry of Education of the Czech Rep.), TAČR SS02030027 and SS05010180 (Technology Agency of the Czech Republic)

How to cite: Bauer, M., Dostal, T., Krasa, J., Schwartz, J., and Bynum, K.: Can we trust our data sources? A case study presenting limits of spatial detail of sediment transport modelling, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-4890, https://doi.org/10.5194/egusphere-egu23-4890, 2023.

EGU23-4967 | Posters on site | HS2.3.1

Assessment of sediment and nutrient sources and their influence on eutrophication: case study from the Czech Republic 

Josef Krasa, Jakub Borovec, Barbora Jáchymová, Miroslav Bauer, and Tomáš Dostál

The purpose of a three-year project QK22020179 is to build a methodology to assess the importance of the impact of sediments deposited in the tributary parts of reservoirs on water quality. The project should describe the dynamics of phosphorus release or capture in sediments in relation not only to the environment of the reservoir, but also to the source basin, the mineralogical composition of the sediment, its granularity and chemistry, and the method of its supply to the reservoirs.

In 2022, the solution was concentrated in the catchment areas of the Bojkovice, Boskovice, Hamry, Seč, Stanovice and Lučina reservoirs. Sediment traps were installed in the inflow reservoirs, continuous models of sediment transport from the catchment were also compiled for the reservoirs, and key parts of the catchment area were defined as potential main sources of sediment. By analyzing the mineralogy and chemistry of the listed source areas, especially on the basis of data from agrochemical analysis of agricultural soils, potential links are now being created between the sediment properties in the inlet parts of the reservoirs and the source areas defined by the model.

The paper will present the current results and the overall methodology with the aim of obtaining feedback in the discussion, because the methodology of potential "fingerprinting" of sediment in catchments and defining the importance of its properties for the behavior of reservoirs in terms of eutrophication has not yet been developed in the Czech Republic, let alone successfully solved.

Research has been supported by projects QK22020179 and SS03010332.

How to cite: Krasa, J., Borovec, J., Jáchymová, B., Bauer, M., and Dostál, T.: Assessment of sediment and nutrient sources and their influence on eutrophication: case study from the Czech Republic, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-4967, https://doi.org/10.5194/egusphere-egu23-4967, 2023.

EGU23-5299 | ECS | Orals | HS2.3.1

The derivation of denitrification conditions in groundwater: Combined method approach and application for Germany 

Tim Wolters, Thomas Bach, Michael Eisele, Wolfram Eschenbach, Ralf Kunkel, Ian McNamara, Reinhard Well, and Frank Wendland

Denitrification in groundwater is an important process that helps to maintain environmental standards, yet there are very few studies that determine the spatial variation of denitrification conditions in aquifers on a regional scale. We introduce a procedure to derive spatially continuous estimates of denitrification conditions in groundwater based on the interpolation of measurements of the redox-sensitive parameters oxygen, nitrate, iron, manganese and DOC, combined with the quantification of denitrification using a 2D-hydrodynamic model based on first-order reaction kinetics. We applied this procedure to Germany, using measured values from more than 24,000 groundwater monitoring sites from 2007 to 2016. Annual concentrations of the five parameters at the monitoring sites were regionalized using an optimized, iterative inverse distance weighting procedure within 15 aquifer typologies for spatial delineation. The annual grids (2007–2016) of each parameter were then overlaid and a median over time was calculated. Discrete ranks were then assigned to the concentrations of each parameter based on their redox class, and ultimately, after overlaying the five parameters, a mean value was calculated describing the nitrate degradation conditions in groundwater. After assigning half-life times and reaction constants to those denitrification conditions, we quantified denitrification in groundwater using the hydrodynamic model WEKU.

To assess the plausibility of the derived denitrification in groundwater, we compared our results with the proportion of denitrified nitrate determined with the N2/Ar method at 820 groundwater monitoring wells in three German Federal States, which showed an overall good agreement. Accordingly, the method presented here is suitable to be used for the regionally differentiated derivation of denitrification conditions in groundwater. For regions with denitrifying groundwater conditions, the results provide an explanation for frequently observed discrepancies between high nitrate emissions from the soil and low nitrate concentrations in the groundwater of intensively used agricultural areas.

How to cite: Wolters, T., Bach, T., Eisele, M., Eschenbach, W., Kunkel, R., McNamara, I., Well, R., and Wendland, F.: The derivation of denitrification conditions in groundwater: Combined method approach and application for Germany, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-5299, https://doi.org/10.5194/egusphere-egu23-5299, 2023.

Current state-of-art studies have been largely focusing on analysing how headwater catchment characteristics influence the sensitivity of the water yield in response to climate change. However, there has been little research combining both hydrological analysis with in situ water quality assessment and understanding how extreme climate events could influence the water quality of the headwater catchment, especially under anthropogenic stress. Therefore, this research aims at understanding the mechanisms of how different types of droughts modify the water quality of an anthropogenically impacted catchment.

The research is performed on the Lauter river, which takes its source from two headstreams, the Scheidbach and the Wartenbach in the Palatinate Forest, Rhineland-Palatinate and flows between the French-German border and ultimately flow into the Rhine River. The discharge time series of 59 years and water quality data of 48 years are being analysed. We will present the methodology of the research and current updates on the progress. The research is planned to proceed in three steps, 1) understanding the water partitioning mechanism and defining different drought types by using the SWAT (The Soil & Water Assessment Tool), 2) studying the water quality behavior under different hydrologic scenarios by conducting in situ water quality monitoring experiments, 3) predicting the water quality trend under future climate change and anthropogenically impacted scenarios. Current results include water quantity trend analysis based on the daily flow rate data at the Salmbacher Passage measuring station on the Lauter river and a primary catchment modeling result with the SWAT.

Keywords: Drought, Water quality, SWAT model, Headwater catchment

How to cite: Liu, X. and de Jong, C.: Analysis of the impacts of droughts on the water quality of the transboundary German-French Lauter catchment with SWAT, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-5376, https://doi.org/10.5194/egusphere-egu23-5376, 2023.

EGU23-5516 | ECS | Orals | HS2.3.1

Comparison of spatio-temporal low-flow models for predicting remobilization of water pollutants 

Johannes Laimighofer, Alexander Pressl, Günter Langergraber, Gabriele Weigelhofer, and Gregor Laaha

Droughts are significant hydrological and environmental hazards that threaten the ecological functioning of water bodies. Low flow with increased water temperature leads to a cascade of hydrochemical processes. This is a particular cause of concern for regions like eastern Austria, where agricultural land use and the projected risk of low flows and increased water temperatures due to climate change are particularly high. Under these scenarios, nutrient release from river sediments may become the dominant factor for the water quality of Iotic ecosystems. The role of this remobilization-potential for water quality is assessed in the project DIRT based on a combination of laboratory experiments with at-site water quality monitoring and regionalized streamflow observations.

Here we focus on space-time models of low flow and stream temperature, which are crucial for upscaling the remobilization potential along the river network. We present a study that compares different models for spatio-temporal low flow regionalization at the monthly scale in eastern Austria.

We evaluate three different statistical models: (i) a tree-based boosting model, (ii) a simple linear regression model with 3-way interactions, and (iii) a combination of a non-linear boosting approach and Top-kriging. Our results show a very high performance for all models, with an overall R² of 0.88 and a median R² of 0.70. The best performance is reached by the combination of Top-kriging with a non-linear boosting approach. However, accuracy of the model is somewhat lower in headwater gauges, whereas non-headwater catchments are even better modeled by a simple spatio-temporal Top-kriging approach. In a next step, the model shall be integrated with laboratory experiments and water-quality monitoring to develop space-time models that can predict the remobilization of pollutants from river sediments.

How to cite: Laimighofer, J., Pressl, A., Langergraber, G., Weigelhofer, G., and Laaha, G.: Comparison of spatio-temporal low-flow models for predicting remobilization of water pollutants, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-5516, https://doi.org/10.5194/egusphere-egu23-5516, 2023.

EGU23-5599 | ECS | Orals | HS2.3.1

Surprising consistency in event-scale nitrate export patterns across catchments 

Carolin Winter, James W. Jawitz, Matthew J. Cohen, Pia Ebeling, and Andreas Musolff

High nitrate concentrations in groundwater and surface water threaten drinking water quality and the integrity of aquatic ecosystems. Discharge events can play a disproportionate role in nitrate mobilization and transport from source to stream, while observed inter-event variability in export patterns is often high. One approach for analyzing the variability of nitrate export is the relationship between nitrate concentrations and discharge. Such C-Q relationships applied across different time scales can inform about source availability (or limitation) of the specific solute and hydrological connectivity to the stream network. Recent studies revealed striking differences between long-term and event-scale C-Q relationships for nitrate, and further that inter-event variability in C-Q relationships decreases with event magnitude (Knapp et al., 2020; Musolff et al., 2021; Winter et al., 2022). This suggests that an integrated measure for nitrate export from long-term data may be insufficient to understand these mechanisms. Here, we hypothesize that event-specific nitrate export patterns systematically diverge from long-term patterns and converge towards chemostatic or dilution patterns at high-magnitude events, depending on the availability and hydrological connectivity of nitrate sources within the catchment. To verify this hypothesis, we analyzed C-Q relationships across 41 catchments in the U.S., using daily discharge and nitrate concentration data. We compared long-term and event-specific C-Q relationships for 5067 discharge events and described inter-event variability in relation to event magnitude. We found that the long-term C-Q relationship was more dynamic than the one averaged for individual events and that the variability of event-specific C-Q slopes significantly decreased with event magnitude, indicating that different mechanisms of source mobilization and transport operate at different time scales and event magnitudes. Notably, high-magnitude events converged towards chemostatic patterns and rarely showed evidence of dilution and thus source limitation, which might hint at substantial nitrogen legacies. The divergence between long-term and event-specific C-Q slopes increased with the share of agricultural area and fertilizer application in the catchment. The consistent patterns in long-term and event-scale nitrate export patterns across a large number of catchments allow us to relate these patterns with the availability, spatial distribution and hydrological connectivity of nitrate sources within the catchments. As such, our study is an important step towards understanding the relevant mechanisms for nitrate mobilization and transport during runoff events.

References

Knapp, J. L., Freyberg, J. von, Studer, B., Kiewiet, L., and Kirchner, J. W.: Concentration-discharge relationships vary among hydrological events, reflecting differences in event characteristics, Hydrol. Earth Syst. Sci. Discuss., 1–27, https://doi.org/10.5194/hess-24-2561-2020, 2020.

Musolff, A., Zhan, Q., Dupas, R., Minaudo, C., Fleckenstein, J. H., Rode, M., Dehaspe, J., and Rinke, K.: Spatial and Temporal Variability in Concentration-Discharge Relationships at the Event Scale, Water Resour. Res., n/a, e2020WR029442, https://doi.org/10.1029/2020WR029442, 2021.

Winter, C., Tarasova, L., Lutz, S. R., Musolff, A., Kumar, R., and Fleckenstein, J. H.: Explaining the Variability in High-Frequency Nitrate Export Patterns Using Long-Term Hydrological Event Classification, Water Resour. Res., 58, e2021WR030938, https://doi.org/10.1029/2021WR030938, 2022.

How to cite: Winter, C., Jawitz, J. W., Cohen, M. J., Ebeling, P., and Musolff, A.: Surprising consistency in event-scale nitrate export patterns across catchments, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-5599, https://doi.org/10.5194/egusphere-egu23-5599, 2023.

EGU23-5744 | Orals | HS2.3.1

Quantification of the reasons for the bird lake brownification in Finland 

Katri Rankinen, Virpi Junttila, Martyn Futter, José Enrique Cano Bernal, Daniel Butterfield, and Maria Holmberg

Browning of surface waters due to increased terrestrial loading of dissolved organic carbon is observed across the Northern Hemisphere. Brownification is often explained by changes in large scale anthropogenic pressures (acidification, climate and land use). We quantified the effect of environmental changes on observed brownification of an important bird lake Kukkia in Central Finland. Water bird densities have decreased there during last decades, probably due to brownification of the lake. We studied past trends of organic carbon loading from catchments based on observations since 1990’s. We created scenarios for atmospheric deposition, climate and land use change to simulate their quantitative effect on brownification of the lake by process-based models (PERSiST for hydrology, INCA-C for carbon loading and MyLake for carbon processes in the lake). Increase in forest cut area appeared to be the primary reason for brownification of the lake. Decrease in acidic deposition has resulted in a lower leaching of dissolved organic carbon, but the effect is small. Runoff and total organic carbon leaching from terrestrial areas to the lake is smaller than it would have been without observed increasing trend in temperature by two degrees. 

How to cite: Rankinen, K., Junttila, V., Futter, M., Cano Bernal, J. E., Butterfield, D., and Holmberg, M.: Quantification of the reasons for the bird lake brownification in Finland, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-5744, https://doi.org/10.5194/egusphere-egu23-5744, 2023.

The requirements under the present River Basin Management Plans (RBMP) for the EU Water Framework Directive (WFD) are to reduce the total nitrogen (TN) loadings to the Hjarbæk Estuary in Denmark from the present (2015-2019) annual loading of 1900 tonnes N to 662 tonnes N in 2027. The catchment area to the estuary represents a total of 1177 km2 and the catchment is drained by four major streams. The Danish national monitoring programme has established gauging stations covering 969 km2 of the catchment area the remaining 208 km2 being ungauged areas. Modelled data on N-leaching from the root zone on agricultural fields and surface water monitoring data on N-export losses are available from the 1980’ies and onward.

A detailed mapping of nitrogen (N) attenuation in the catchment have been conducted at a scale of ca. 15 km2 (ID15 sub-catchments) including mapping of both N-retention in groundwater and surface waters as well as N-delays in groundwater in Karst sub-catchments. The mapping shows large differences in N-retention in groundwater within the ID15 sub-catchment (<20 % to >80 %) and the same large variation is seen for N-retention in surface waters (<20 % to >80 %). An analysis of delays in the transport for N from fields to surface waters have shown that especially one of the four monitored catchments (Simested stream) experiences a long delay in N repsonses (> 10 years).  

A new portfolio of N mitigation measures to be adopted at source (e.g. catch crops, early seeding, set a side, afforestation) or during transport from field to surface water (several types of constructed wetlands, riparian buffers and restored wetlands) has been scientifically approved and made available for farmers by the Danish EPA and Agricultural Agency.

The huge N-reduction needed in the Hjarbæk coastal catchment (65%) will require management efforts where farmers and authorities utilize both source oriented and transport oriented mitigation measures. These solutions should be implemented in a targeted manner guided by the local N-retention maps, as well as using all available monitoring data to pinpoint high-risk areas for N-leaching from fields and N-exports from the four sub-catchments as well as the ungauged areas. In this presentation we will showcase examples on how both targeted and collective mitigation measures can optimally be dosed in the Hjarbæk coastal catchment to reach the targets set in the RBMP 3.   

How to cite: Windolf, J., Tornbjerg, H., Larsen, S., and Kronvang, B.: Use of high spatial resolution nitrogen attenuation mapping in groundwater and surface waters for planning how to reach nitrogen reduction goals in 3rd River Basin Management Plans: Hjarbæk coastal catchment, Denmark, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-5800, https://doi.org/10.5194/egusphere-egu23-5800, 2023.

EGU23-6014 | Orals | HS2.3.1 | Highlight

Land to water phosphorus transfer processes under climate change 

Per-Erik Mellander, Daniel Hawtree, Golnaz Ezzati, Conor Murphy, Jason Galloway, Leah Jackson-Blake, Magnus Norling, Phil Jordan, Simon Pulley, and Adrian Collins

Water quality in European rivers is degraded by nutrient loss to waters, and such problems can be exacerbated by climate change. Climate smart mitigation measures are needed and these require insight into the underlying processes of nutrient loss under future weather conditions. To address this, the aim of this study was to assess how a changing climate may alter phosphorus (P) mobilisation, delivery and impact in two hydrologically contrasting agricultural river catchments (ca 11 km2) in Ireland. As part of the WaterFutures project and the Agricultural Catchments Programme, The Simply P model was calibrated with 10 years of high frequency data of hydro-chemo-metrics for the two catchments. Five downscaled Global Climate Models (CNRM-CM5, EC-EARTH, HadGEM2-ES, MIROC5 and MPI-ESM-LR) were used to simulate two far-future climate scenarios, one intermediate emission pathway (RCP4.5) and one intensive emission pathway (RCP8.5). The scenarios were used to estimate P concentrations and loads for the coming century. A newly developed P Mobilisation index (ratios of concentration percentiles) and P Delivery index (ratios of mass load percentiles) was used to assess changes in P transfer for the modelled P concentrations and P loads.

In a hydrological flashy catchment, it was estimated that climate change alone may increase mean annual total P (TP) concentration from 0.120 mg/L monitored between 2010-2019 to 0.184 mg/L by 2070-2100. A corresponding increase in Delivery index by around 25% and 40% (for RCP4.5 and RCP8.5, respectively) but no change in Mobilisation index suggests that the impact is mostly due to enhanced hydrological connection and/or reduced P retention. The mean annual total reactive P (TRP) concentration was estimated to show minor decreases from 0.079 mg/L to 0.075 mg/L. A corresponding decrease in the Mobilisation index by around 5% and 10% (for RCP4.5 and RCP8.5, respectively) but an increase in Delivery index by 25% and 40% suggests a possible decrease in soil P detachment and/or solubilisation, limiting the increased delivery potential. The same analysis on data from a groundwater-fed catchment suggests that climate induced changes in TP and TRP concentrations were mostly related to delivery processes for TP.

The underlying processes for P losses associated with climate change are likely to be different for TP and TRP and for catchments with different hydrological controls. Such information helps to target more resilient land use mitigation methods and further design these for scenarios of future weather conditions and land use.

How to cite: Mellander, P.-E., Hawtree, D., Ezzati, G., Murphy, C., Galloway, J., Jackson-Blake, L., Norling, M., Jordan, P., Pulley, S., and Collins, A.: Land to water phosphorus transfer processes under climate change, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-6014, https://doi.org/10.5194/egusphere-egu23-6014, 2023.

EGU23-6212 | ECS | Orals | HS2.3.1

Reducing future coastal eutrophication under global change in Europe 

Aslıhan Ural-Janssen, Carolien Kroeze, and Maryna Strokal

Agricultural production and sewer systems have been the main contributors to nutrient losses to surface waters. A high load of nutrients by rivers causes coastal eutrophication and leads to harmful algal blooms. Several negative environmental impacts of eutrophication include the production of toxins by cyanobacteria, fish kills, increased production of algae, and reduction in coral reef communities and aquatic vegetation. Despite the environmental policies and targets in Europe, rivers transport large amounts of nutrients to coastal waters and thus, coastal eutrophication is still an issue. Half of the nitrogen (N) exports by the European rivers to coastal waters is from agricultural production. The losses can increase if effective actions are not taken to improve agricultural management. As a result, the risks of coastal eutrophication will likely increase in the future coupled with global change including socio-economic development and climate change.

This study aims to assess the future river export of N and phosphorous (P) and explore options to reduce associated coastal eutrophication in Europe under global change with a focus on sustainable agriculture and urbanization. We use the MARINA-Nutrients (Model to Assess River Inputs of Nutrients to seAs) model for 601 European basins to quantify river exports of N and P in the 21st century, and calculate an indicator for coastal eutrophication potential (ICEP) to evaluate their impacts on coastal waters. We develop scenarios based on existing storylines (e.g., Shared Socio-economic Pathways, Representative Concentration Pathways) to quantify the impacts of socio-economic and climate changes on future coastal pollution in Europe. In our scenarios, we reflect on environmental policies (e.g., Green Deal, reduced waste, and improved wastewater treatment) from optimistic views.

Model results show that under the current practice approximately one-third of the European basin area, including 59% of the total population, is responsible for over half of nutrient losses to European rivers. Over one-fourth of river exports of N and P ended up in the Atlantic Ocean and the Mediterranean Sea around 2017-2020, respectively. On the other hand, intensive agriculture and technological development will increase nutrient pollution in coastal waters. For example, river exports of N and P to coastal waters are projected to increase by approximately 20-30% by 2050 under a scenario with high global warming and high urbanization rates. The Atlantic Ocean is projected to receive the largest portion of nutrient losses in the future compared to other European seas in 2050. In our scenarios, we analyze optimistic options to reduce future coastal eutrophication in European coastal waters. during the presentation, we will show the effects of several optimistic options (e.g., recycling of organic waste) on reducing coastal eutrophication. We will discuss the possible implications of the Green Deal and European environmental policies for coastal water quality in Europe.

How to cite: Ural-Janssen, A., Kroeze, C., and Strokal, M.: Reducing future coastal eutrophication under global change in Europe, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-6212, https://doi.org/10.5194/egusphere-egu23-6212, 2023.

EGU23-6952 | ECS | Orals | HS2.3.1

The Derivation of Irish Water Quality via Sentinel-2 Imagery 

MinYan Zhao and Fiachra O'Loughlin

The water quality in Republic of Ireland is regulated under the water framework directive (WFD), which requires all EU countries achieve good ecological and chemical status before 2027. However, the Irish Environmental Protection Agency (EPA) reports in 2021 that just half of the rivers, lakes, estuaries, and coastal waters achieved satisfactory or higher status.

Water quality in Ireland is monitored by traditional methods, which cannot provide timely spatiotemporal information. While remote sensing (RS)-based water quality monitoring work have been carried out in many EU countries in accordance with WFD directive, the use of RS for water quality estimation in Ireland has not been fully explored.

To explore the feasibility of RS for Irish waters, Sentinel-2 surface reflectance has been used to assess several water quality parameters (chlorophyll-a, transparency, turbidity, suspended solids (SS), total nitrogen, total phosphorus, biological oxygen demand (BOD), dissolved oxygen, and chemical oxygen demand (COD)) from March 2017 to July 2022. These were compared with the Sentinel-2 surface reflectance data resulting in a total of 6509 corresponding data points.

Initially, empirical algorithms were used to derive water quality concentrations in rivers, lakes, estuaries, and coastal waters separately. Initial results indicate that the combination of green and blue bands was correlated to coastal waters’ chlorophyll-a (R2 = 0.27). For chlorophyll-a in transitional waters, the combination of red and red edge was highly correlated. However, no single band or combination were suitable for deriving chlorophyll-a in lakes. For SS, red and near infrared band are useful in detecting changes in coastal and transitional waters. Whereas, for lakes and rivers, blue and shortwave infrared band were best to derive SS. In addition to empirical algorithms, multiple machine learning methods have been used to derive water quality parameters from Sentinel-2 reflectance, with the aim of exploring if machine learning approaches can improve estimates compared with the empirical approaches.

How to cite: Zhao, M. and O'Loughlin, F.: The Derivation of Irish Water Quality via Sentinel-2 Imagery, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-6952, https://doi.org/10.5194/egusphere-egu23-6952, 2023.

EGU23-7069 | ECS | Orals | HS2.3.1

Post-drought nitrate mobilization in German catchments     

Felipe Saavedra, Andreas Musolff, Jana Von Freiberg, Ralf Merz, Kay Knoll, Christin Müller, Manuela Brunner, and Larisa Tarasova

Nitrate excess in rivers is caused by anthropogenic nitrogen sources, such as agriculture and wastewater. Diffuse sources stemming from agricultural fertilization can remain in the soil for long periods of time as a legacy and are mobilized through hydrological pathways that connect sources with rivers. Previous studies show that drought periods can increase nitrogen stored in the soil due to lower nitrate transport to streams and less nitrate uptake by plants due to dry conditions. This accumulation of nitrogen during drought and its subsequent transport under wet conditions during the post-drought period can result in high nitrate concentrations in rivers.

In our study, we analyze the nitrate response of 190 German rivers during hydrological post-drought conditions from 1978 to 2019. We define droughts as periods with more than 30 consecutive days of discharge deficit using a variable threshold method and post-droughts as 100-day periods following the termination of a drought. We particularly focus on post-drought periods in the winter season that display the most pronounced concentration anomalies. Our results show that during the winter post-drought period, 66% of the catchments export higher nitrate concentrations compared to non-drought conditions, with 19% of the catchments exporting significantly higher nitrate concentrations (Kruskal-Wallis test, p-value<0.05). Catchments that exhibit a significant increase in nitrate concentrations during winter post-drought periods tend to be characterized by higher annual precipitation and shallower aquifers, indicating that fast hydrological transport could be a key factor in the winter post-drought delivery of nitrate excess. A projected increase in the frequency of severe droughts due to climate change could lead to more frequent post-drought episodes with high nitrate concentrations in the future. Understanding the main drivers of post-drought transport of nitrate across catchments is crucial for focusing management efforts efficiently.

How to cite: Saavedra, F., Musolff, A., Von Freiberg, J., Merz, R., Knoll, K., Müller, C., Brunner, M., and Tarasova, L.: Post-drought nitrate mobilization in German catchments    , EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-7069, https://doi.org/10.5194/egusphere-egu23-7069, 2023.

EGU23-7478 | ECS | Posters on site | HS2.3.1

The controlling mechanism of nitrogen dynamics across a large river basin 

Hongkai Qi, Yi Liu, Xingxing Kuang, Xin Luo, and Jiu Jimmy Jiao

Investigating the dynamics and distribution of nitrogen (N) in river networks is essential for environmental management and pollution control. However, the controlling mechanisms of N dynamics across large watersheds are not well understood. In this study, we examined N concentration and stable isotopes (δ2H-H2O, δ18O-H2O, δ15N-NO3- and δ18O-NO3-) in river water and groundwater through field sampling from 284 sites across the Pearl River Basin, China. Preliminary results show that nitrate (NO3-) is the primary form of riverine dissolved inorganic nitrogen (DIN), and NO3- concentration is three times higher in the groundwater than in river water (mean of  330.5 ± 480.1 μmol/L v.s. 93.2 ± 65 μmol/L). The signature of δ15N-NO3- and δ18O-NO3- indicates that riverine nitrogen is primarily fromsoil organic N. The δ18O-NO3- values ranged from 2.76‰ to 7.52‰, indicating that nitrification is the dominant process in the N cycle of river water across the basin. Denitrification is not apparent in the water column because δ15N-NO3- does not show a negative correlation with NO3- concentration. We find that the source region has the highest NO3- concentration (187.1 ± 16 μmol/L) in river waters. The high cropland proportion (36.5% ± 5%) leads to higher soil N accumulation due to fertilization, and the highest oxidation-reduction potential (222.3 ± 7 mV) indicates the strongest oxidation environment for nitrification. As the nitrification process produces H+, which can consume carbonate and increase dissolved inorganic carbon (DIC), the highest DIC concentration (3139.3 ± 777.5 μmol/L) further proves the most robust nitrification process in the source regions. In conclusion, nitrification can control N dynamics and dominate NO3- distribution in river water in large watersheds.

How to cite: Qi, H., Liu, Y., Kuang, X., Luo, X., and Jiao, J. J.: The controlling mechanism of nitrogen dynamics across a large river basin, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-7478, https://doi.org/10.5194/egusphere-egu23-7478, 2023.

EGU23-7759 | ECS | Orals | HS2.3.1

Performance of a Parsimonious Phosphorus Model (SimplyP) in Two Contrasting Agricultural Catchments in Ireland 

Daniel Hawtree, Jason Galloway, Ognjen Zurovec, Leah Jackson-Blake, Magnus Norling, and Per-Erik Mellander

The Agricultural Catchment Program (ACP) has collected over a decade’s worth of high frequency data for a number of hydrologic and chemical indicators at agricultural catchments around the Republic of Ireland. This dataset provides an excellent foundation for conducting robust modelling studies assessing long term hydrochemical dynamics in agricultural sites, within the context of EU regulations around the protection of water quality.

To examine the risks of phosphorus (P) export from agricultural catchment in this context, the parsimonious phosphorus model SimplyP was applied to two ACP study sites. These sites are in close proximity and are of similar size to each other but have contrasting physical characteristics and hydrochemical dynamics. Site “A” is dominated by grasslands with heavy soils and is P export risky, while site “B” is primarily arable land-use on lighter soils and has a lower risk of P export.

In these catchments, SimplyP was used to simulate streamflow, sediment, and phosphorus (PP, TRP, TP) over the period of 2010 – 2019. The model is calibrated and validated independently three times to different objective functions (NSE, KGE, NSE log) to provide models focused on peak flows, balanced, and low flows, respectively. Model performance is evaluated over the entire calibration and validation period, as well as year-by-year assessments, which highlights the influence of meteorological and antecedent moisture conditions on model behaviour.

How to cite: Hawtree, D., Galloway, J., Zurovec, O., Jackson-Blake, L., Norling, M., and Mellander, P.-E.: Performance of a Parsimonious Phosphorus Model (SimplyP) in Two Contrasting Agricultural Catchments in Ireland, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-7759, https://doi.org/10.5194/egusphere-egu23-7759, 2023.

EGU23-7990 | Posters on site | HS2.3.1

Probabilistic modelling of water quality in the Ramganga River, India, informed by sparce observational data 

Miriam Glendell, Rajiv Sinha, Bharat Choudhary, Manudeo Singh, and Surajit Ray

Impaired water quality continues to be a serious problem in surface waters worldwide. Despite extensive regulatory water quality monitoring implemented by the Government of India over the past two decades, the spatial and temporal resolution of water quality observations, the range of monitored contaminants and data related to characterisation of point source effluents are still limited. In addition, discharge data for trans-boundary rivers is considered sensitive information and is not publicly available. Hence, quantifying, and mitigating pollutant loads and planning effective mitigation strategies are hindered by data paucity and there is an urgent need for the development of decision support tools (DST) that can account for these uncertainties.

In this study, we tested the application of a probabilistic DST based on Bayesian Belief Networks, to evaluate pollution risk from nutrients (phosphate, nitrate, ammonia), sediments and heavy metals (Cd, Cr, Cu, Pb, Zn) in the Ramganga river basin (30,839 km2), the first major tributary of the Ganga in the state of Uttar Pradesh, India, and is understood to be a significant source of pollution into the Ganga River, contributed from a range of industries, domestic sources and intensive farming practices. Bayesian belief networks are graphical causal models that enable to integrate observational data (both spatial and temporal) with data from literature and expert knowledge within a probabilistic framework, whilst accounting for uncertainty.

The objectives of this study were to 1) develop a parsimonious conceptual model of the system that allows harnessing diverse but limited data, 2) evaluate the important components of the system to inform further data collection and management strategies, and 3) simulate plausible management scenarios. We simulated the impacts of point source management interventions on pollution risk, including provision of sufficient municipal sewage treatment plant (STP) capacity, enhanced STP treatment levels and sufficient industrial wastewater effluent treatment capacity. We found a clear effect of enhanced STP interventions on improved regulatory standard compliance for nitrate (from 92% to 95%) and phosphate (from 33% to 41%). However, the effect of interventions on heavy metal pollution risk was not clear, due to considerable uncertainties related to the lack of reliable discharge data and the characterisation of industrial effluent quality. The parsimonious DST helped to collate the available understanding related to water quality impacts from multiple pollutants in the Ramganga river basin, while sensitivity analysis highlighted critical areas for further data collection.

How to cite: Glendell, M., Sinha, R., Choudhary, B., Singh, M., and Ray, S.: Probabilistic modelling of water quality in the Ramganga River, India, informed by sparce observational data, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-7990, https://doi.org/10.5194/egusphere-egu23-7990, 2023.

EGU23-9879 | ECS | Posters on site | HS2.3.1

High frequency monitoring of dissolved organic matter dynamics in urban headwaters: implications of monitoring resolution for process inference 

hongzheng zhu, Kieran Khamis, David M. Hannah, and Stefan Krause

Submersible optical sensor technology provides new opportunities for high frequency observations of riverine dissolved organic matter (DOM) and nutrients that cannot be achieved from traditional discrete sampling. High frequency data are essential to reveal the DOM transport, processing and transformation changes during storm events. However, previous studies have tended to focus on DOM mobilization and transport in rural catchments, largely neglecting urban headwater systems despite DOM behaviour being highly variable given complex interactions between varying sources and pathways in urban catchments. The few studies that have explored urban DOM dynamics have done so over relatively short timescales (e.g., seasonal) and have not systematically explored the impacts of monitoring resolution on DOM process interpretation. This is surprising given the dynamic nature of urban hydrological systems. To address this research gap, we collected high frequency water quality and hydro metrological data (5 min resolution, 10/21-10/22) for an urban headwater stream (Bourn Brook, Birmingham, UK). An in-situ multi-parameter sensor (Proteus, Eureka) was deployed for monitoring tryptophan-like fluorescence (TLF, Ex 275 nm/ Em 350 nm) and humic-like fluorescence (HLF, Ex 325 nm/ Em 470 nm). High temporal resolution data (5 minutes) were aggregated into 10,15, 30, 60,120,180 minutes datasets to explore the impacts on concentration-discharge (C-Q) patterns and hysteresis, thus aim to understand the effects of monitoring rate on interpretation of solute pathways and determine the sufficient temporal resolution to capture the salient urban DOM storm-driven dynamics. Our results highlight that at coarser monitoring frequency (>30 min), the “first-flush” of liable DOM is hard to detect, but the recession dynamic (usually consisting of more humic-like compounds) is still adequately captured. At monitoring frequencies > 30 min, both HLF and TLF displayed clockwise hysteresis indices, suggesting proximal DOM sources were delivered through the urban drainage system on the rising limb. However, figure of eight hysteresis was most commonly identified for both fluorescence peaks when sub-15 min data were investigated, which suggested a more complex relationship with multiple sources of DOM being mobilised during storm events. Furthermore, chemodynamic behaviour for both HLF and TLF was observed at monitoring frequencies >30 min; yet at higher monitoring frequencies TLF displayed chemostatic behaviour at high discharge. Our works not only emphasised the importance of conducting high frequency monitoring when designing urban water quality studies as coarser resolution monitoring will not fully capture the urban DOM dynamic, but also provides new insight into the importance of carefully considering monitoring frequency and provides guidance for adaptive monitoring approaches if installations are constrained by power requirements or data storage.

How to cite: zhu, H., Khamis, K., Hannah, D. M., and Krause, S.: High frequency monitoring of dissolved organic matter dynamics in urban headwaters: implications of monitoring resolution for process inference, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-9879, https://doi.org/10.5194/egusphere-egu23-9879, 2023.

EGU23-10405 | ECS | Posters on site | HS2.3.1

The influence of erosion sources on sediment-related water quality attributes 

Simon Vale, Hugh Smith, John Dymond, Rob Davies-Colley, Andrew Hughes, Arman Haddadchi, and Chris Phillips

Erosion of fine sediment and its delivery to streams pose significant issues for freshwater quality and  downstream receiving environments. Increased sediment delivery can lead to negative impacts due to changes to visual clarity (VC) and nutrient levels, which can degrade freshwater and marine environments. Most research on sediment in catchments focuses primarily on the total mass or quantity of sediment in relation to erosion, sediment transport, and deposition. In contrast, ‘quality’ aspects, notably particle size as it affects water quality, are not often evaluated, particularly in terms of their erosion source. This is problematic, as the physical qualities of sediment, which strongly affect environmental behaviour and influence water quality, may vary across catchments, geological parent materials, and erosion processes. Here, we assess the extent to which sources, defined spatially according to erosion process and geological parent material, may be discriminated, and classified by their sediment-related water quality (SRWQ) attributes. This involved 1) evaluating variability in SRWQ attributes across different sources; 2) reclassifying sources to the minimum number needed to adequately represent variation in attributes; and 3) assessing the potential influence of erosion sources on instream VC.

Erosion sources were sampled across two New Zealand catchments representing six types of erosion and eight parent materials. Sample measurements focused on particle size, organic matter content, and light beam attenuation (which is convertible to VC). Particle size attributes included three size fractions (<0.063mm, 0.063 – 2mm, and >2mm), particle size distribution (PSD) attributes (mean, D10, D50, and D90, based on both surface area (sur) and volume (vol) distributions). Organic matter related attributes included the percentage of particulate organic carbon (POC), particulate organic nitrogen (PON), inorganic suspended solids (InorgSS), and volatile suspended solids (VSS). Given its importance for predicting VC, light beam attenuation coefficient (beam- ) was measured and converted into beam-  to use as a SRWQ attribute.

The results indicate that SRWQ attributes show significant variation across erosion sources. The extent to which attributes differed between sources often related to whether there was a strong association between a specific erosion process and parent material. The 19 a priori source classifications were reduced to 5 distinct sources that combined erosion process and parent material (i.e., bank erosion – alluvium; mass movement – ancient volcanics; mass movement – sedimentary; surficial erosion; gully – unconsolidated sandstone). At low sediment concentration (SC), the impact of erosion source on VC became most evident ranging from 2.6 to 5.6 m at a SC of 5 g m-3. These findings showed how catchment sources of sediment, in addition to sediment concentration, influence VC, and highlight the need to consider quality as well as quantity of material supplied to stream networks when planning erosion control.

How to cite: Vale, S., Smith, H., Dymond, J., Davies-Colley, R., Hughes, A., Haddadchi, A., and Phillips, C.: The influence of erosion sources on sediment-related water quality attributes, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-10405, https://doi.org/10.5194/egusphere-egu23-10405, 2023.

EGU23-10487 | ECS | Posters on site | HS2.3.1

Predicting river water quality under different environmental factors and its significance with Machine Learning approach 

Sun Hee Shim, Hye Won Lee, and Jung Hyun Choi

River Water Quality (RWQ) is significantly influenced by natural and anthropogenic activities such as land use and land cover changes. Urbanization has led to an increase in impervious surfaces, which alters hydrological flow pattern and delivers non-point pollutants to the stream more efficiently. In addition, intensification of agricultural activities can result in the increased nutrient loads due to alternations in surface soil properties. Hence, it is necessary to understand the impact of surrounding environment with specific emphasis on geographical factors (e.g. climate change, land use patterns and landscape metrics) on the RWQ in order to develop sustainable water quality management strategies effectively. We collected pollutant concentration Biochemical Oxygen Demand (BOD), Total Phosphorus (T-P), and  Total Organic Carbon(TOC) from monitoring stations in the Nakdong River watershed. To utilize field monitoring data, we developed a Machine Learning (ML) models (DNN, XGBoost and Random Forest) to predict RWQ in accordance with different environmental factors. SHapley Additive exPlanations (SHAP) was used to illustrate the significance of land uses and landscape patterns on RWQ in Nakdong River. The results of this study can (1) demonstrate the relationship of water quality variables with land uses and landscape patterns, (2) identify pollution sources and factors that affect Nakdong River, and (3) support catchment managers and stakeholders in evaluating the benefits and risks of water management strategies in priority areas.

How to cite: Shim, S. H., Lee, H. W., and Choi, J. H.: Predicting river water quality under different environmental factors and its significance with Machine Learning approach, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-10487, https://doi.org/10.5194/egusphere-egu23-10487, 2023.

Landscape disturbance pressures in forested headwater regions can modify both the supply and transport of sediment from hillslopes to river networks. The effects of these pressures on phosphorus (P) mobility in rivers vary regionally depending upon the type and severity of the disturbance as well as interactions amongst other watershed scale controls such as climate, geology, hydrology and vegetation. The present study examines P dynamics in a gravel-bed river across multiple disturbances during environmentally sensitive periods of summer low-flow. Six study sites were selected to represent a gradient of sediment pressures from landscape disturbances (e.g., roads, harvesting, wildfire, sewage) in the Crowsnest River, Alberta. Interactions between fine bed sediments and soluble reactive phosphorus (SRP) were examined using equilibrium phosphorus concentrations (EPC0) and diffusive fluxes of SRP from the riverbed sediments. Diffusive fluxes at each site were estimated using gradients of SRP between pore-water in the bed and water column, determined from vertical distributions of SRP in the gravel matrix measured with pore-water peepers. SRP concentrations in pore-water were variable among depths and sites but were elevated downstream of the stream reach receiving primary sewage effluent outflow. Larger SRP concentration gradients were observed at sites that had either smaller substrate or increased biofilm activity. The EPC0 and diffusive pore-water flux data suggest that fine sediment in the riverbed acted as a source of SRP to the water column under low-flow conditions when the risk for eutrophication is higher and such conditions favor the growth of biofilms. EPC0 concentrations showed large inter- and intra-site variability indicating heterogeneous responses to disturbance. Furthermore, overlapping, and varying proportions of historic and contemporary harvesting, roads, road-stream or culvert crossings, and OHV use confounds the apportionment of landscape impacts. This study provides insight into the potential for the regulation of P by sediments in gravel-bed rivers following a range of landscape disturbance effects.

How to cite: Stone, M. and Watt, C.: Cumulative disturbance effects on phosphorus mobility in a gravel-bed river at the catchment scale, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-10511, https://doi.org/10.5194/egusphere-egu23-10511, 2023.

EGU23-10669 | Posters on site | HS2.3.1

Prediction and analysis of algal bloom trend in Yeongsan River using EFDC 

Hye Yeon Oh, Hye Won Lee, and Jung Hyun Choi

 Green algae, which is called water bloom, refers to a phenomenon in which cyanobacteria proliferate in large quantities and change the color of water to green. Algal bloom is one of the major water quality problems in freshwater ecosystems because it causes oxygen depletion in deep layer, oxygen supersaturation and toxicity in the surface layer, odor generation, fish death, and scum formation. Green algae are caused by hydraulic factors such as increased residence time due to the installation of hydraulic structures such as weirs, as well as physicochemical factors such as excessive influx of nutrients and rise in water temperature. One of Korea's four major rivers, the Yeongsan River, which originates in Damyang-gun, Jeollanam-do and flows into the West Sea, is experiencing water pollution problems, including algae, as the water quality and hydraulic environment change due to the construction and opening of weirs. Accordingly, Gwangju Metropolitan City, a large city where more than 80% of the population of the Yeongsan River basin resides, and Seungchon Weir, one of the two artificial weirs located in the Yeongsan River, were selected as the study area. In this study, the Environmental Fluid Dynamics Code (EFDC), a three-dimensional hydraulic and water quality dynamics model that can simulate various water quality indicators such as Chl-a, DO, T-N, and T-P, which was used to predict the trend of algal bloom in the study area.

How to cite: Oh, H. Y., Lee, H. W., and Choi, J. H.: Prediction and analysis of algal bloom trend in Yeongsan River using EFDC, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-10669, https://doi.org/10.5194/egusphere-egu23-10669, 2023.

EGU23-10753 | Orals | HS2.3.1

Modeling urban phosphorus export to receiving waters: magnitudes, speciation, and management implications 

Mahyar Shafii, Stephanie Slowinski, Yuba Bhusal, Md Abdus Sabur, Calvin Hitch, William Withers, Fereidoun Rezanezhad, and Philippe Van Cappellen

Understanding phosphorus (P) dynamics in urban landscapes is an emerging research topic as P export from urban landscapes towards aquatic ecosystems causes eutrophication-related challenges in these environments. We investigated P export and forms in four research sites in Ontario, Canada, including three urban catchments and a stormwater pond, all located within the Great Toronto Area in the drainage basin of Lake Ontario. We conducted P speciation laboratory analyses on runoff and suspended sediment samples to measure total P (TP), total dissolved P (TDP), dissolved reactive P (DRP), dissolved unreactive P (TDP–DRP), and PP (TP–TDP). Multiple linear regression (MLR) models were also developed to quantify annual loadings of these P species. Models indicated that P loadings in our sites were close to the lower limit of values reported in the literature, with the simulated range of 0.2—0.46 kg ha-1 yr-1 for TP export, 0.06—0.168 kg ha-1 yr-1 for TDP, 0.011—0.073 kg ha-1 yr-1 for DRP, 0.026—0.095 kg ha-1 yr-1 for DUP, and 0.163—0.288 kg ha-1 yr-1 for PP. In our MLR models, precipitation explained a large fraction of variability in loadings with the median of 58% across all models. Moreover, we realized that as the proportion of residential land within the drainage area increased, larger amounts of P loadings were exported at the catchment scale. Results also implied that pond served as a major P sink, with annual retention of 82, 93, 91, 94, and 77% for TP, TDP, DRP, DUP, and PP, respectively. Mass balance analyses based on sequential P extraction in the sediment core samples revealed that P retention was attributed to sedimentation in the ponds, as well as chemical precipitation of P with calcium mineral phases. In terms of P composition, most of P export in our sites (72—88%) were in particulate form. Besides, the ratio between dissolved forms and TP were the highest in the catchment with the largest amount green spaces. This study demonstrates that, as land-use characteristics impose variations in constituent loadings, urban P management options also have to be varying from a catchment to another. However, sediment removing practices such as the use of ponds will certainly be a reliable P retention approach as most of urban P could be sediment-bound. Furthermore, enhancing the formation of calcium phosphate and other redox-stable mineral phases could be explored as a best management practice in existing and new ponds for improving P retention.  

How to cite: Shafii, M., Slowinski, S., Bhusal, Y., Sabur, M. A., Hitch, C., Withers, W., Rezanezhad, F., and Van Cappellen, P.: Modeling urban phosphorus export to receiving waters: magnitudes, speciation, and management implications, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-10753, https://doi.org/10.5194/egusphere-egu23-10753, 2023.

Through precipitation, nutrients on the surface flow along the river and flow out to the coast. In order to effectively manage coastal water quality and ecosystem, it is essential to study the changes in terrestrial nutrient discharge to the coast through streamflow. However, research on long-term on estuarial or coastal water quality and river streamflow data remains limited particularly around the Korean Peninsula where long-term data for water quality and streamflow are available.
Here, this study aimed to investigate changes in inland nutrient fluxes the coastal regions around the Korean Peninsula and the contribution of changes of streamflow and water quality. The overarching question of this study is to which extent can changes in nutrient flux discharge be contributed by changes in streamflow or nutrient concentrations? First, we used observational data of rivers during the spring months (March through May) to assess changes in the nutrient fluxes over 2012–2021, which were springtime TN, TP and Chlorophyll-a nutrient fluxes from the inland to the coastal regions of the surrounding Korean Peninsula. Second, we conducted analytically a simple decomposition analysis of the relative contribution of changes in streamflow and nutrient concentration to the changes of nutrient fluxes model.
Results show that the change rate of annual spring nutrient (TN, TP, Chlorophyll-a) flux was more affected by streamflow flowrate (84, 51, 91%, respectively) than nutrient concentration (19, 48, 5%, respectively). In addition, the regional analysis of the nutrient flux on the Korean Peninsula (the western, northern, and eastern sides) showed the contribution of the western side was the largest to changes the total nutrient fluxes.
This study emphasized the importance of hydrological linkage between the water and nutrient cycles through an analytical approach, highlighting the potential impacts of changes of nutrient fluxes on off-shore ecological communities and aquacultural productivities.  

How to cite: Kim, Y. and Kam, J.: Observed Changes in Springtime Nutrient Flux Budget along the Korean Peninsula (2012-2021): Roles of Streamflow and Nutrient, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-10889, https://doi.org/10.5194/egusphere-egu23-10889, 2023.

EGU23-11646 | ECS | Posters virtual | HS2.3.1

Urban impact on water quality of a coastal catchment in Brazil 

Julia dos Santos da Silva, Patrícia Kazue Uda, Henrique Von Linsingen Pereira, and Priscilla Kern

Rapid and unplanned urban development has become critical to urban water resources in developing countries. In general, water quality degradation of rivers and ecosystems are result of lack of sewage treatment and urban management failures. In Brazil, the sanitary sewage system and the stormwater system are separated, and irregular connections of sewage to the pluvial network are common. In this context, it is fundamental to monitor water quality to understand how rivers are being modified by urbanization and, in the future, to propose measures for environmental recovery and for regulation of sanitation. Conceição Lagoon (CL), situated in the south of Brazil, is the largest lagoon system (21 km2) of Santa Catarina state. Similar to other regions in Brazil, water quality is degraded as a result of the urbanization of its basin. Thus, this study analyzed the influence of urbanization on the water quality of the largest sub-basin affluent to CL, the João Gualberto (JG) Basin (9.92 km2). Five field work were conducted, with measurements in loco and laboratory analysis, in two sample sites: upstream of urbanization (contribution area equal to 0.17 km2) and downstream of urbanization (contribution area equal to 6.07 km2). Were analyzed parameters capable of indicating contamination by sewage; chlorophyll-a; total coliforms (TC); fecal coliforms (FC); biochemical oxygen demand (BOD); total phosphorus; dissolved oxygen (DO); pH; ammonia, nitrate and nitrite. In addition, flow measurements to calculate the nutrient loads arriving in the lagoon and the trophic index (TRIX), which characterizes the trophic conditions of water bodies. Results were evaluated in regards to the resolution of CONAMA 357/05, which defines the maximum concentrations of water quality parameters for water bodies in Brazil. Chlorophyll-a concentrations were generally low. In regards to fecal coliforms, high values of 2419.6 MPN for TC were found at all points, with a maximum of 21.8 MPN of FC in upstream and 1046.2 MPN in downstream. Lower values of BOD, phosphorus, nitrite, ammonia and nitrate were obtained for the most upstream monitored point, and the highest values for downstream. The downstream of the river exceeded the limits in 0.110 mg/L N-NO2, 11.548 mg/L N-NO3 and 0.18 mg/L P, considered as the main sources of nutrients for the eutrophication process. DO values decreased from upstream to downstream, remaining within the limit such as for the pH. Differences in concentration of all parameters analyzed, at the upstream and downstream points, indicate domestic sewage releases, as it passes through urbanization. In relation to TRIX, the river presented an oligotrophic state in its upstream and eutrophic state for its downstream. The research allowed to confirm the JG river, the main tributary of the lagoon, contributes to the release of loads of nutrients and, consequently, to the eutrophication process of CL, expanding the understanding of the influence of surface runoff from the basin on the hydrodynamics of the lagoon.

How to cite: dos Santos da Silva, J., Kazue Uda, P., Von Linsingen Pereira, H., and Kern, P.: Urban impact on water quality of a coastal catchment in Brazil, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-11646, https://doi.org/10.5194/egusphere-egu23-11646, 2023.

EGU23-11746 | ECS | Orals | HS2.3.1

Quantifying the Downstream Impact of Implementing Irrigation in a Semi-Arid Mediterranean Basin in NE of Spain 

Víctor Altés, Miquel Pascual, Maria José Escorihuela, and Josep Maria Villar

Irrigation in arid and semi-arid regions is key to maintain the productivities and the well-being of farmers. However, irrigation is an important source of pollution to rivers due to the impact of agricultural drainage [1], which may contain high levels of salts, nutrients and other pollutants. In the present study we quantified the impact of implementing irrigation in a 10,000 ha semi-arid basin of the Noguera Ribagorçana river (Ebro Basin, NE Spain). Water quality data obtained during 20 years (2002-2022) in four different sampling points in the river (three before, and one after the main agricultural drainage returns of the basin, which drains 4,366 ha) were analyzed, focusing on nitrate concentration (NO3-, ppm), phosphate concentration (PO43-, ppm), and electrical conductivity of the water (EC, dS/m). In 2002, less than 4,000 ha were under irrigation and during the studied period, a total of 5,571 hectares were brought under irrigation progressively over time, with the implementation of a new irrigation district in the area. Results showed a significative difference in the concentration of NO3- in the river water before and after the main agricultural drainage return of the new irrigation district. However, phosphorous concentration and electrical conductivity showed no significative differences between the sampling points before and after the main agricultural drainage returns. On the other hand, NO3- values at the sampling point after the main agricultural drainage return have increased over time as it did the irrigated area. Thus, along the 18 km of the Noguera Ribagorçana river observed in this study, NO3- levels have increased on average from 1.7 ppm at the first sampling point to 10.9 ppm at the last sampling point, after the returns of agricultural drainage in the basin. Therefore, we could state that implementing irrigation in 5,571 ha represents an increase of 9.2 ppm of NO3- in the water of the Noguera Ribagorçana river in the studied area.

[1] Blann, K. L.; Anderson, J. L.; Sands, G. R.; Vondracek, B. Effects of Agricultural Drainage on Aquatic Ecosystems: A Review. Crit. Rev. Environ. Sci. Technol. 2009, 39 (11), 909–1001. https://doi.org/10.1080/10643380801977966.

 

How to cite: Altés, V., Pascual, M., Escorihuela, M. J., and Villar, J. M.: Quantifying the Downstream Impact of Implementing Irrigation in a Semi-Arid Mediterranean Basin in NE of Spain, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-11746, https://doi.org/10.5194/egusphere-egu23-11746, 2023.

EGU23-12117 | ECS | Posters on site | HS2.3.1

Watershed Characteristics and Water Quality in Suburban River in Tokyo: Asakawa River 

Masato Oda, Koji Kodera, Yoichi Morimoto, and Yoshihiro Igari

1. Introduction

In the Asakawa River, a suburban river in Tokyo, there are issues of water quality such as wastewater problems or substance runoff from forest ecosystem. To understand the water quality and characteristics of the river basin, not only field surveys but also comprehensive studies combining various methods are required. This study aims to clarify the characteristics of the Asakawa River watershed based on the results of field surveys, water quality analysis, and statistical analysis using the results.

2. Method

To understand the watershed characteristics and water quality of the Asakawa River, data analysis, field survey, water quality analysis, statistical analysis, and comparison with previous studies were conducted. Data analysis was conducted to obtain population trends and population density by township from the census results, changes in the watershed land use ratio from the National Land Numerical Data, and population trends by sewage treatment method from the Hachioji City Basic Plan for Domestic Wastewater Treatment 2014. Field surveys were conducted with monthly observations during a 17-month period from June 2020 to October 2021, and self-recording instrument observations from November 2021 to January 2022. Water quality analysis was conducted for total organic carbon and major dissolved constituents in July 2020, October 2020, January 2021 and September 2021. Ammonium ion, nitrite, nitrate and phosphate were measured of the samples of September,2021 . In the statistical analysis section, a cluster analysis was performed using the September 2021 data, which has the largest number of measured items. Comparison with previous studies was made between the electrical conductivity values of Ogura (1980) and Ota and Omori (2004) and the electrical conductivity values of the present field observations.

3. Results and Discussion

Monthly observations showed an increase in electrical conductivity (EC) during the winter months. The pH was low in winter, due to groundwater, and high in summer, possibly due to algal carbonate assimilation. In summer, pH was higher, because of carbon assimilation by algae. Nitrate ions were detected upstream in many locations, probably due to nitrogen saturation in the forest ecosystem. High concentrations of nitrate were detected in the Yamadagawa Riv., where wastewater from a sewage treatment plant flows in. It indicates that the wastewater from the plant has not been completely treated. Ammonium and nitrite were also detected upstream, indicating the effluent from the septic tank may have had an effect. Cluster analysis produced five clusters. In the Yudonogawa Riv., the upstream and downstream observation points were classified into different clusters, suggesting that water quality changes as the river flows downstream.

4. Conclusion

From this study, four issues in the Asakawa Riv. watershed were identified: the pollution caused by septic tank effluent in upper stream, nitrate runoff due to nitrogen saturation in the forest ecosystem upstream, pollution caused by the inflow of sewage treatment plant effluent into the small tributary named Yamadagawa Riv. and pollution caused by domestic wastewater from the Yudonogawa Riv. watershed which locates in southern part of its basin. To solve these problems, improvement of the watershed environment is required.

How to cite: Oda, M., Kodera, K., Morimoto, Y., and Igari, Y.: Watershed Characteristics and Water Quality in Suburban River in Tokyo: Asakawa River, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-12117, https://doi.org/10.5194/egusphere-egu23-12117, 2023.

EGU23-12436 | ECS | Orals | HS2.3.1

Impact of deforestation on catchment hydrology and nitrogen losses 

Mufeng Chen, Angela Lausch, Seifeddine Jomaa, Salman Ghaffar, Burkhard Beudert, and Michael Rode

Forest status in natural catchment is substantially important for hydrology and water quality, but it has been increasingly altered by human activities and climatic factors. Due to recent rapid changes in forest cover, there is an urgent need for hydrological water quality models which can adapt to these changing environmental conditions. The objective of this study was to analyse the impact of rapid continuous forest decline on nitrogen losses in a temperate mountain range catchment using a dynamic setting of the HYPE (HYdrological Predictions for the Environment) model. The modified model was applied to the Große Ohe catchment, Germany, which has experienced severe forest dieback (caused by bark beetle infestations) and its recovery over the last three decades. The model was validated by using also additional 25 years data from an internal gauge station (Forellenbach) and two soil measurement sites. Three scenarios, namely, no forest change, deforestation with subsequent regeneration, and deforestation without regeneration, were compared to identify key factors influencing catchment discharge and nitrogen export due to deforestation and regeneration. Results showed that the model performed well at the Große Ohe catchment scale, with Nash-Sutcliffe Efficiency values of 0.77 and 0.57 for discharge and IN concentration, respectively, and percentage BIAS values of -11.6% and 0.5%, respectively, during the validation period. Similar good performances were also observed at other scales. The simulation results proved that the improved model was able to (1) well capture the timing of peak flows and the seasonal dynamics of inorganic nitrogen (IN) concentration, and more importantly, (2) reflect the first increasing and then decreasing trend of discharge and IN concentration, in accordance with the deforestation and forest regeneration, respectively. By comparing scenarios, after experienced forest dieback without regeneration, the discharge and IN concentration exports were 24.9% and 160%, respectively, greater than those of scenario without forest change. However, the discharge and IN concentration exports were only 3.63% and 39.6% greater, respectively, with the help of continuous regeneration, indicating that forest regeneration is important for restoring hydrological and water quality status in the catchment. Compared to non-change scenario, the deforestation scenario exhibited decreased annual plant uptake of 34.7%, and strong increase in annual denitrification and N mineralization suggesting that the increased nitrogen export was likely induced by the reduction in vegetation uptake and the increased availability of soil nitrogen from tree residues. Overall, the adapted mechanistic modelling under the changing catchment forest conditions can strongly support forest management in terms of water quality.

How to cite: Chen, M., Lausch, A., Jomaa, S., Ghaffar, S., Beudert, B., and Rode, M.: Impact of deforestation on catchment hydrology and nitrogen losses, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-12436, https://doi.org/10.5194/egusphere-egu23-12436, 2023.

EGU23-13252 | ECS | Posters on site | HS2.3.1

Stoichiometry on the edge - Humans induce strong imbalances of reactive C:N:P ratios in streams 

Alexander Wachholz, Joni Dehaspe, Pia Ebeling, Rohini Kumar, Andreas Musolff, Felipe Saavedra, Carolin Winter, Soohyun Yang, and Daniel Graeber

Anthropogenic nutrient inputs lead to severe degradation of surface water resources, affecting aquatic ecosystem health and functioning. Ecosystem functions such as nutrient cycling and ecosystem metabolism are not only affected by the over-abundance of a single macronutrient but also by the stoichiometry of the reactive molecular forms of dissolved organic carbon (rOC), nitrogen (rN), and phosphorus (rP). So far, studies mainly considered only single macronutrients or used stoichiometric ratios such as N:P or C:N independent from each other. We argue that a mutual assessment of reactive nutrient ratios rOC:rN:rP relative to organismic demands enables us to refine the definition of nutrient depletion versus excess and to understand their linkages to catchment-internal biogeochemical and hydrological processes. Here we show that the majority (94%) of the studied 574 German catchments show a depletion or co-depletion in rOC and rP, illustrating the ubiquity of excess N in anthropogenically influenced landscapes. We found an emerging spatial pattern of depletion classes linked to the interplay of agricultural sources and subsurface denitrification for rN and topographic controls of rOC. We classified catchments into stoichio-static and stochio-dynamic catchments based on their degree of intra-annual variability of rOC:rN:rP ratios. Stoichio-static catchments (4036% of all catchments) tend to have higher rN median concentrations, lower temporal rN variability and generally low rOC medians. Our results demonstrate the severe extent of imbalances in rOC:rN:rP ratios in German rivers due to human activities. This likely affects the inland-water nutrient retention efficiency, their level of eutrophication, and their role in the global carbon cycle. Thus, it calls for a more holistic catchment and aquatic ecosystem management integrating rOC:rN:rP stoichiometry as a fundamental principle.

How to cite: Wachholz, A., Dehaspe, J., Ebeling, P., Kumar, R., Musolff, A., Saavedra, F., Winter, C., Yang, S., and Graeber, D.: Stoichiometry on the edge - Humans induce strong imbalances of reactive C:N:P ratios in streams, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-13252, https://doi.org/10.5194/egusphere-egu23-13252, 2023.

EGU23-14138 | ECS | Posters on site | HS2.3.1

Spatial vs temporal variability in German river water quality 

Linus S. Schauer, James W. Jawitz, Matthew J. Cohen, and Andreas Musolff

River water quality is degraded by a multitude of diffuse and point sources impeding ecosystem functioning and constituting a severe risk for human water security all over the world. Monitoring campaigns are the basis of evaluating water quality by characterizing probability of concentrations in time and space, allowing to identify solute source zones and flow paths. This knowledge can then aid in the development of effective water quality management strategies. However, it is not clear, whether current monitoring approaches provide sufficient information to allow to soundly characterize concentration probability over time and localize pollution sources in space. We propose a space-time variance framework to characterize spatial and temporal variation in river water quality and analyze its interplay. Specifically, we assess for discharge and two contrasting solutes (anthropogenic: NO3-, biogenic: DOC) by analyzing time series data across 1386 stations in Germany (Ebeling et al. 2022) . Variability is quantified by using the Coefficient of Variation (CV) of mean temporal and spatial variation of subsets of catchments. We find a large span of both spatial and temporal CV for discharge, NO3- and DOC. Overall, variability of discharge was considerably higher in time and space than the variation of NO3- and DOC. Differences between CVs of NO3- and DOC were smaller than expected from their different landscape sources. Apart from analyzing national to continental-scale data records, we plan to analyze archetypal patterns of solutes by utilizing a stochastic modelling approach. Ultimately, the aim is to inform stakeholders whether monitoring strategies such as synoptic sampling are viable approaches and to disentangle anthropogenic and natural drivers to illuminate their role for spatial and temporal variation in river ecosystems.

Ebeling, P., Kumar, R., Lutz, S. R., Nguyen, T., Sarrazin, F., Weber, M., Büttner, O., Attinger, S., and Musolff, A.: QUADICA: water QUAlity, DIscharge and Catchment Attributes for large-sample studies in Germany, Earth Syst. Sci. Data, 14, 3715–3741, https://doi.org/10.5194/essd-14-3715-2022, 2022.

How to cite: Schauer, L. S., Jawitz, J. W., Cohen, M. J., and Musolff, A.: Spatial vs temporal variability in German river water quality, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-14138, https://doi.org/10.5194/egusphere-egu23-14138, 2023.

1. Introduction
There are many volcanoes in the Japanese archipelago, and their formation factors and magma composition vary from volcano to volcano. Due to these differences in characteristics, it is expected that the water quality of rivers and springs around volcanoes will also differ. Based on the results of the measurement and analysis of river water quality in volcanic areas such as Mt.Tokachi, Mt.Asama, Mt.Kusatsu-Shirane, Mt.Ontake, Mt.Hakone, and Shinmo-dake where surveys and water sampling were conducted, we compared water quality in the water environment around each volcano and tried to understand the relationship between the characteristics of volcanoes and water quality.

2. Overview of the target area and survey/analysis methods
The target volcanoes were Mt.Tokachi, Mt.Kusatsu-Shirane, Mt.Asama, Mt.Ontake, Mt.Hakone, and Mt.Shinmoe. Each of these sites was surveyed several times to several dozen times, with frequency ranging from monthly to half a year, for several years. Water temperature, pH (RpH), electrical conductivity (EC), flow rate, COD, etc., as well as TOC (total organic carbon) and major dissolved constituents were measured in the field.

3. Results
The electrical conductivity (EC) values were generally low in the rivers around Ontake, and some rivers in Mt.Kusatsu-Shirane showed EC similar to that of the surrounding hot spring water due to the influence of the underground hydrothermal system. Mt.Tokachi, Mt.Kusatsu-Shirane, Mt.Hakone, and Mt.Shinmoe, and especially Mt.Kusatsu-Shirane and Mt.Hakone have rivers with values exceeding 3,000μS/cm. Since EC is affected by the recent eruption history, surrounding land use, wind-transported salt, and other factors, we will examine the effects of each of these factors to determine the influence of geological formation age and underground eruptive activity on the surface water quality of the volcanoes. The results suggest the possibility that the geological formation age and subterranean eruptive activity may have an impact on the surface water quality.

4. Conclusion
Based on the results of surface water quality analysis at volcanoes, we compared the characteristics of the water environment between volcanoes and attempted to understand the relationship between volcanic activity and surface water quality. The relationship between final volcanic activity (magmatic eruptions) at volcanoes and EC values around volcanic bodies shows a certain correlation, but it is suggested that the quality of surface water is affected by volcanic activity depending on the development of hydrothermal systems at each volcano and the most recent volcanic activity. In the future, we would like to explore methods for comparative research between volcanoes, paying attention to the effects of land use and wind-blown salt around volcanoes, and focusing more deeply on the relationship between dissolved constituents and volcanic activity.

How to cite: Igari, Y., Kodera, K., and Horiuchi, M.: Study on Comparative Assessment of Water Environment around Volcanoes Focusing on Surface Water Quality -Case studies in volcanic areas around Japan-, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-15467, https://doi.org/10.5194/egusphere-egu23-15467, 2023.

Many surface water lakes in northern Europe have seen a rise in their organic matter content. When the water is used for human consumption, this has an indirect effect on human health, by increasing the risk of pathogens appearance and of biofilm formation after water treatment. Besides, organic matter negatively affects the color, odor and taste of water, which displeases the consumers. In order to ensure a good drinking water quality at the tap, its treatment should thus be adapted to the organic matter content.

In this study we (i) characterize the trend and seasonality patterns of organic matter in the Gileppe Lake over the last 20 years and (ii) unravel mechanisms causing the observed fluctuations using time series statistical modelling. The water reservoir created by the Gilleppe dam in the North of Wallonia has an available volume of 3.100.000 m³. It is used to supply a hydro-electric power plant, and to provide drinking water to the city of Verviers and its surroundings. The water producer « Société Wallonne des Eaux (SWDE) » extracts an annual volume of around 14 million m³ to that end. The SWDE has been measuring the quality of the extracted water since 1991, at an increasing frequency. These measurements include parameters related to organic matter content such as total organic carbon (TOC), color and chemical oxygen demand.

The TOC concentrations in the Gileppe lake indicate there has been a rise in organic matter in the Gileppe lake since the 90’s, as the concentration was 3,7 mg/l in October 1997, and increased to 10,4 m/l in October 2019. The TOC also has a seasonal variability, with the highest concentration peaks being reached during the autumn.

We characterize the evolution of the potential drivers of the increasing trend and the seasonality: climate (precipitation, T°), land use (mainly forest cover area and type) and anthropogenic pressure (presence of septic tanks, wastewater release, agricultural runoff). We then investigate if, according to the literature, the evolution of these variables could explain of the observed organic matter trends and seasonality.

How to cite: Verstraeten, E., Alonso, A., and Vanclooster, M.: Characterizing the drivers of organic matter fluctuations in surface water lakes: the case of the Gileppe water reservoir in Wallonia (Belgium), EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-15570, https://doi.org/10.5194/egusphere-egu23-15570, 2023.

Keywords

Freshwater pollution, climate change, water quality monitoring, emerging contaminants, diffuse agricultural pollution, catchment monitoring.

Abstract

Despite the implementation of river basin management plans across EU, river water quality is in decline with agriculture, forestry and hydromorphological pressures now the dominant pressure for river waters in Ireland.  The number of high quality river sites reflecting natural, undisturbed conditions declined from 31.6% of river sites monitored in 1990 to just 1.1% of monitored sites in 20211

Climate change increases in heavy rainfall events in conjunction with flooding will lead to increased suspended solid and nutrient loadings in rivers2 with a substantial upsurge in the intensity of winter rainfall together with increasing frequency in heavy rainfall events3 in Ireland4 leading to increased pollution of freshwater systems and a surge in transient pollution events.

‘Reliable high quality information on the environmental quality of surface waters’ is critical for  agencies to make evidence based decisions on appropriate management measures to restore water quality at European scale5.  However current water quality monitoring programmes in Ireland rely heavily on grab water samples which is inadequate at detecting transient pollution6

Are transient pollution events contributing to increased solids, nutrients loads and emerging contaminants affecting aquatic species in these declining Q5 sites?  This research aims to investigate by applying field assessments, sensor technology and automatic sampling to two river stations in the North West of Ireland; on the River Unshin a high ecological status water body and on the River Owenmore, a moderate ecological status water body.  As the pathway from land to waters for multiple diffuse agricultural pollutants, including phosphorus, sediment and pesticide are similar7 and turbidity can be used as an indicator for suspended sediment8, a baseline turbidity survey is being carried out to identify a ‘trigger level’ above which the collection of water samples is initiated. 

Other research has shown no simple relationship between discharge, turbidity and precipitation9 but initial baseline data obtained shows some correlation with turbidity and increased flows.

References

(1)          Trodd, W.; O’Boyle, S.; Gurrie, M. 2022.

(2)          Whitehead, P.; Butterfield, D.; Wade, A., SC070043/SR1; Environment Agency: Bristol, 2008; p 115.

(3)          Murphy, C.; Broderick, C.; Matthews, T. K. R.; Noone, S.; Ryan, C. EPA Research Report 277; Maynooth University, 2019; p 76. https://www.epa.ie/publications/research/climate-change/research-277-irish-climate-futures-data-for-decision-making.php (accessed 2023-01-09).

(4)          O’Connor, P.; Meresa, H.; Murphy, C., Weather 2022. https://doi.org/10.1002/wea.4288.

(5)          Kristensen, P.; Bogestrand, J. Surface Water Quality Monitoring — European Environment Agency January 1996; European Topic Centre on Inland Waters; Publication; National Environmental Research Institute: Denmark, 1996; p 82. https://www.eea.europa.eu/publications/92-9167-001-4 (accessed 2023-01-09).

(6)          Regan, F.; Jones, L.; Ronan, J.; Crowley, D.; Mcgovern, E.; Mchugh, B.; 2018.

(7)          Thomas, I.; Bruen, M.; Mockler, E.; Werner, C.; Mellander, P.-E.; Reaney, S. M.; Rymsezewicz, A.; McGrath, G.; Eder, E.; Wade, A.; Collins, A.; Arheimer, B.; EPA RESEARCH PROGRAMME 2021–2030; EPA Research Report 396; University College Dublin: Dublin, 2021; p 64. https://www.epa.ie/publications/research/water/Research_Report_396.pdf.

(8)          Uhrich, M. A.; Bragg, H. M.; Water-Resources Investigations Report, 2003; p 2. https://doi.org/10.3133/wri034098.

(9)          Wang, K.; Steinschneider, S. Water Resources Research 2022, 58 (10), e2021WR031863. https://doi.org/10.1029/2021WR031863.

How to cite: Cronin, L., Regan, F., and Lucy, F. E.: Detection of transient pollution events in an Irish river catchment in the context of increasing frequency and intensity of rainfall events due to climate change, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-15993, https://doi.org/10.5194/egusphere-egu23-15993, 2023.

EGU23-16201 | ECS | Orals | HS2.3.1

Rapid Phosphate Monitoring in Irish Freshwater Systems Using a Novel Microfluidic Colorimetric System 

Rachel Bracker, Lisa Cronin, Aironas Grubliauskas, Louis Free, Joyce O’Grady, Sean Power, Karen Daly, Nigel Kent, Fiona Regan, and Blánaid White

The discharge of phosphorus associated with wastewater has decreased significantly in Europe over the past 25 years1, however the problem of diffuse pollution persists2.  Studies have shown that regulatory monitoring can miss elevated spikes in phosphorus concentrations3 and high frequency monitoring is required4. Such programmes are resource intensive, requiring effective tools which enable appropriate water quality data collection and quality assurance5.

A low cost, portable, and rapid phosphate detection system is needed to enable the quick detection of phosphate in areas affected by high phosphate levels6. A new system is being developed by evolving a colorimetric detection system using microfluidic lab-on-a-disc technology which has previously been demonstrated7. It utilizes a micro-spectrometer and the molybdenum blue method, and has been built with the intent of requiring limited training.

The range of the system is 5-400 µg/L, which encompasses the threshold value of 35 µg/L P for Irish rivers and groundwaters8. The system is extremely portable due to its compact size and weighing less than 2 kg. With a run time of 15 minutes per ten samples, it enables the in-situ detection of phosphate for rapid on-site monitoring.

To test the system, rivers in the northwest of Ireland were identified. Three of these rivers have historical orthophosphate readings in the range of 5 - 47 µg/L and two others were reported considerably higher at 84 µg/L.  

With this microfluidic phosphate detection system, rapid in-situ detection and reliable, real-time monitoring of phosphorus in freshwater systems can be achieved. 

References:

1)European waters -- Assessment of status and pressures 2018 — European Environment Agency. https://www.eea.europa.eu/publications/state-of-water (accessed 2022-06-13).

2)Biddulph, M.; Collins, A. l.; Foster, I. d. l.; Holmes, N. The Scale Problem in Tackling Diffuse Water Pollution from Agriculture: Insights from the Avon Demonstration Test Catchment Programme in England. River Research and Applications 2017, 33 (10), 1527–1538. https://doi.org/10.1002/rra.3222.

3)Fones, G. R.; Bakir, A.; Gray, J.; Mattingley, L.; Measham, N.; Knight, P.; Bowes, M. J.; Greenwood, R.; Mills, G. A. Using High-Frequency Phosphorus Monitoring for Water Quality Management: A Case Study of the Upper River Itchen, UK. Environ Monit Assess 2020, 192 (3), 184. https://doi.org/10.1007/s10661-020-8138-0.

4)Bowes, M. J.; Palmer-Felgate, E. J.; Jarvie, H. P.; Loewenthal, M.; Wickham, H. D.; Harman, S. A.; Carr, E. High-Frequency Phosphorus Monitoring of the River Kennet, UK: Are Ecological Problems Due to Intermittent Sewage Treatment Works Failures? Environ. Monit. 2012, 14 (12), 3137–3145. https://doi.org/10.1039/C2EM30705G.

5)Quinn, N. W. T.; Dinar, A.; Sridharan, V. Decision Support Tools for Water Quality Management. Water 2022, 14 (22), 3644. https://doi.org/10.3390/w14223644.

6)Park J.; Kim, K. T.; Lee; W. H. Recent advances in information and communications technology (ICT) and sensor technology for monitoring water quality. 2020, Water, 12 (2)

7)O’Grady, J., Kent N., Regan, F. (2021). Design, build and demonstration of a fast, reliable  portable phosphate field analyser. Case Stud. Chem. Environ. Eng., 2020, 4, 100168

8)Tierney, D.; O’Boyle, S. Water Quality in 2016: An Indicators Report; Environmental Protection Agency, Ireland: Wexford, 2018; p 48.

How to cite: Bracker, R., Cronin, L., Grubliauskas, A., Free, L., O’Grady, J., Power, S., Daly, K., Kent, N., Regan, F., and White, B.: Rapid Phosphate Monitoring in Irish Freshwater Systems Using a Novel Microfluidic Colorimetric System, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-16201, https://doi.org/10.5194/egusphere-egu23-16201, 2023.

EGU23-16398 | ECS | Orals | HS2.3.1

Main drivers of the seasonal and annual changes in phosphorus content in the Guadaira river (South of Spain) 

Manuel Jesús Jurado-Ezqueta, Eva Contreras, Cristina Hidalgo, Laura Serrano, and María José Polo

High amounts of nutrients favor the growth of algae that consume oxygen from the aquatic environment causing eutrophication. In the case of phosphorus, it comes mainly from two sources: fertilizers washed from agricultural areas by runoff water and urban and industrial development. In the first case, the phosphorus loads do not have a clear point of entry into the water channels, whereas in the second one, the phosphorus loads can be generated from point sources, such as discharges from the wastewater treatment plants (WWTP) but also from non-point sources, such as urban areas runoff in episodes of intense rainfall. 
The main purpose of this work is to analyze the content of phosphorus in water for more than 40 years and inquiry into the origin of the sources that may have produced the phosphorus loads. For this purpose, the Guadaira river basin (South of Spain), where agricultural land uses converge with numerous human activities resulting in high pressures on water quality, was selected. 
The results highlight that the phosphates threshold value established for good/moderate state (0.32 mg PO4/l) is exceeded by 96% of the measurements during the period 1981-2022 in a water quality control point located downstream of the main WWTP, which threat the wastewater of Seville, and that in addition collects the contributions from the other WWTPs and agricultural lands located in the basin. The episodes of sediment contribution that occurred during the period 1981-2022 were analyzed at this control point, and from the 184 episodes found, 30 episodes may have been due to runoff (which also may have originated from agricultural areas or from the overflow of water collectors) (type 1 episodes) and 79 may have been due to urban spills (type 2). 80% of both types of episodes were found to be higher than 1.5 mg/l being able to reach concentration values of up to 14 mg/l. Most of the episodes of dry months were categorized as type 2, reaching the highest concentration values (8-17 mg/l), while type 1 episodes were mostly present in rainy months.

Finally, despite the increase of the stable population (+0.52% ∼ +1.42% per year between 2000 and 2012) and tourism (average ≈ +3.23% per year), the WWTP improvement has achieved a decrease in the mean phosphorus concentrations of -0,2% per year. Despite the investment in the WWTP of the basin is necessary to improve its operation and efficiency as well as its adaptation to the increase in population and tourism to ensure better water quality of the water resources.

Acknowledgements: This work has been funded by the project TransDMA – Adaptation of the Water Framework Directive to the Andalusian reality: The Guadalquivir estuary as an integrated management model, promoted by the Ministry of Economy, Knowledge, Business and University and co-financed by the operational program FEDER 2014-2020 in Andalusia.

How to cite: Jurado-Ezqueta, M. J., Contreras, E., Hidalgo, C., Serrano, L., and Polo, M. J.: Main drivers of the seasonal and annual changes in phosphorus content in the Guadaira river (South of Spain), EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-16398, https://doi.org/10.5194/egusphere-egu23-16398, 2023.

EGU23-16608 | Posters on site | HS2.3.1

Robustness of the nitrate transfer model NIT-DRAIN in an artificially drained agricultural area 

Hocine Henine, Samy Chelil, Cedric Chaumont, and Julien Tournebize

Nitrate leaching due to excessive agricultural fertilization affects the quality of both surface and ground water. The presence of subsurface drains in agricultural areas introduces significant modifications to the hydrological behavior and results in the increase of nutrients and fertilizers losses from farmland to surface water. The recent development of the NIT-DRAIN conceptual model allows the simulation of nitrate transfer at the agricultural drainage system outlet and the estimation of the initial prewinter nitrogen pool (PWNP), equivalent to the remaining nitrogen pool at the start of winter season. This model was applied to three representative drained agricultural areas in France (La Jaillière, 1 ha; Gobard, 36 ha and Rampillon, 355 ha). The hourly drainage discharge and nitrate concentration data are recorded over a period of several years. The objective of this study is to evaluate of the spatiotemporal robustness of the NIT-DRAIN model, by testing the functioning of the model regarding a single or a generic set of model parameters for the three study sites.

The results showed that the model estimation of the PWNP is more precise at the small scale (Jailliere site). At the large scale, the PWNP estimation is slightly different from the measurement (<10kgN/ha). The model calibration for each study site shows high model performance for nitrate fluxes and concentrations, with Nash-Sutcliffe criterion greater than 0.6. These performances are preserved when calibrating a generic set of parameters to all the three sites. These results validate the robustness of the NIT-Drain model. This study present a simplified and operational approach for the quantification of PWNP applied to the subsurface drained agricultural lands by measuring nitrate concentration at outlet instead of soil core sampling.

How to cite: Henine, H., Chelil, S., Chaumont, C., and Tournebize, J.: Robustness of the nitrate transfer model NIT-DRAIN in an artificially drained agricultural area, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-16608, https://doi.org/10.5194/egusphere-egu23-16608, 2023.

Due to rising water quality-related issues, a periodic and continuous monitoring system is mandatory for inland water bodies. Water quality estimation is essential for water resource management and the sustainability of riverine ecosystems. Existing in-situ, field-based, and wet laboratory estimations, although precise and accurate, account for the lack of spatial and temporal variability and represent point sampled assessment. With a high temporal resolution and fine spatial resolved scaling, remote sensing data, including the Landsat-8,9 series, and Sentinel-2 series, consecutively provide high-spatio-temporal resolution observations for real-time analysis. The Google server and cloud-based Google Earth Engine (GEE) platform support image collections, atmospherically-radiometrically corrected imagery, and large-data processing. Taking the inland waterbodies of Delhi as the study area, this study is carried out in GEE to (i) design, inquire and pre-process all Landsat and Sentinel series observations that coincide with in situ measurements; (ii) extract the spectra to develop empirical models for water quality parameters and (iii) visualize the results graphically using geospatial distribution maps, time-series charts, and create a web-application. Water quality parametric analyses were conducted for Optically Active constituents (OAC), i.e., chlorophyll-a, suspended solids, and turbidity. Validation with an independent site location is the next area of study for estimating the predicted and observed values. Spectral characteristics show correlation and similarity with the field data and active optical constituents. Besides visualizing long-term spatial and temporal variabilities through thematic maps and time-series charts, anomalies such as eutrophication at specific sites can also identify using the models developed. An online application is in progress to allow users to explore and analyze water quality trends using the latest Landsat-9 dataset. Integrating remotely-sensed images, in situ measurements, and cloud computing can offer new opportunities to implement effective monitoring programs and understand water quality dynamics.

How to cite: Galodha, A., Lall, B., Ahammad, S. Z., and Anees, S.: Spatio-temporal, geospatial, and time series analysis of water quality estimation using Landsat 8,9, Sentinel-2, and MODIS series for the region of India: A Google Earth Engine based web-application, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-16876, https://doi.org/10.5194/egusphere-egu23-16876, 2023.

EGU23-17358 | ECS | Orals | HS2.3.1

Modeling the impact of land-use and climate change on water quality of a deep dam reservoir 

Yu-I Lin, Mei-Siang Yu, Hue-Shien Chang, and Shu-Yuan Pan

Te-Chi Reservoir is an multipurpose reservoir, which supplies drinking water for a population of ~2,800,000 and generate hydroelectric power in the Taichung city, Taiwan. In the past 10 years, this reservoir experienced several events of algal blooms and extreme drought. According to the historical water quality data, the frenauency of the trophic state for the reservoir has increased in the recent years. The N/P ratios of the reservoir are generally greater than 15, indicating that the limited nutrient of eutrophication is phosphorous. In this study, we developed an integrated model to predict the water quality of the reservoir using an input of 10-year observational data. A hydrological stream flow model (i.e., SWAT) was integrated with the simple phosphorous (P) input-output models (i.e., the Vollenweider model) to simulate the change of the trophic state and the concentration of P in the reservoir. We first investigated the hydrological variability impact on the P load in past three year when the extreme weather (drought) happened.The results showed that the concentraion of total phosphorous (TP) was significantly influenced by the inflow of the river to the reservoir and the precipitation (rainfall). The simulated concentrations of TP in dry seasons were typically higher than that in the wet seasons. During the drought, the internal loading, such as resuspension, played a significant source of P for the reservoir. We also investigated the sources and loads of key water pollutants, especially nitrogen and phosphorous, from the spatial aspect in the watershed of the reservoir. The results indicated that the TP loads of each sub-catchment area ranged from 2.76 to 4.12 kg/h. Furthermore, in order to understant the feasibility of establishment of riparian buffer strip, the effect of the land use change on water quality was simulated. This study demonstrated the application of the integrated SWAT-Vollenweider model for a reservior to identify the drivers of pollutants for managing its watershed to mitigate the potential of eutrophication.

How to cite: Lin, Y.-I., Yu, M.-S., Chang, H.-S., and Pan, S.-Y.: Modeling the impact of land-use and climate change on water quality of a deep dam reservoir, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-17358, https://doi.org/10.5194/egusphere-egu23-17358, 2023.

Chromium (VI) [Cr(VI)] is abundantly used for several industrial applications especially in stainless steel production and as an anti-corrosive agent in ceramics, textile industries and tanneries. Despite its versatile uses, Cr (VI) is a major environmental threat and is a known carcinogen. Therefore, proper precaution must be implemented while working with Cr (VI) or while disposing it after use. Due to improper handling and lack of proper care, Cr(VI) is still found in industrial wastewaters or landfill sites. The Cr(VI) in landfills can leach into the ground during rainfall and can risk the contamination of the groundwater causing a health catastrophe when consumed. This study focuses on effective Cr(VI) remediation by the process of adsorption. Magnetite particles synthesized by co-precipitation method at various temperatures (room temperature of 25οC, 60οC and 90οC) are used as an absorbent for achieving maximum removal efficiency of Cr(VI) from water. An initial concentration of 10mg/l at pH 7.2 and time of contact 10 minutes is taken as the starting parameters for Cr(VI) for the batch adsorption studies. The surface morphology, chemical composition and the magnetic properties of the magnetite particles are determined from FESEM (Field Emission Scanning Electron Microscope), EDS (Energy-Dispersive  Spectroscopy) and VSM (Vibrating Sample magnetometer) characterization methods, respectively. The synthesis of the magnetite particles at various temperatures can affect both its physical (mainly pore size, shape, texture etc.) and magnetic properties and therefore can pose significant changes on the adsorption efficiency. The effect of the magnetite particle dose, pH of Cr(VI), time of contact between the magnetite particles and Cr(VI) and the effect of the change in the concentration of Cr(VI) are predicted in this study. A special focus is given on determining the variation in the magnetic properties of the magnetite particles due to different temperatures of synthesis. In case of any such noteworthy change in the magnetic properties, the alteration in the individual adsorption capacities of the iron-oxide particles are highlighted in this study. Langmuir and Freundlich isotherm models are used to predict the adsorption mechanisms.

Keywords: Adsorption; Magnetite particles; Characterization; Magnetic properties; Langmuir and Freundlich isotherms.

How to cite: Ganguly, S. and Ganguly, S.: Adsorption of Hexavalent Chromium by magnetite particles synthesized at various temperatures: effect of magnetic properties of the particles on individual adsorption mechanisms, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-160, https://doi.org/10.5194/egusphere-egu23-160, 2023.

EGU23-1646 | Orals | HS2.3.2

Hydrological driver for leptospiroses abundance in a small tropical catchment ? Example from the New Caledonian leptospirosis hot-spot 

Pierre Genthon, Roman Thibeaux, Nazha Selmaoui-Folcher, Caroline Tramier, Malia Kainiu, Marie-Estelle Soupé-Gilbert, Kavya Wijesuriya, and Cyrille Goarant

Leptospirosis is a zoonosis caused by pathogenic Leptospira shed in the urine of mammals, able to survive in water and soils and remobilized during rainy events. Pathogenic Leptospira (PL) concentrations were measured together with hydrological variables in the upper Thiem river, near the Touho village, a hot spot for leptospirosis in the main island of New Caledonia (a small tropical island itself a hot spot for leptospirosis). Two hundred twenty-six water samples were collected at the outlet of as 3 km2 sub-watershed, which is frequented by invasive mammals (rodents, deer and wild pigs) known to be animal reservoirs for leptospirosis. The main features of our results highlight that (i) samples collected at the beginning of a rain event occurring after a dry period may contain high PL concentrations (ii) PL concentrations at the heart of a wet period exhibit significant correlation with rainfall, water level and suspended matter concentration (SMC) (iii) elevated PL concentration may be observed a few days after the main flood event and within weakly turbid waters, (iV) the largest PL concentrations were observed in the middle and at the end of a wet rain season. Comparison of PL concentrations with hydrological data (rainfall, water level, SMC, soil moisture) reveals that they cannot be explained by a linear combination of hydrological variables. Indeed, nonlinear machine learning models provided a fair fit to observed data (99% of explained variance on their decimal logarithm and a mean ratio of 2.5 between raw observed data and modeled values). Comparison of identical machine learning models of water levels, SMC and PL concentration shows that the remaining error in PL concentration data does not only result from the limited dataset but rather from the intrinsic characteristics of the Leptospira signal. Our results may help to refine recommendations for leptospirosis control towards local populations. Further studies in larger watersheds draining in more populated areas will be conducted to confirm and extend these findings

How to cite: Genthon, P., Thibeaux, R., Selmaoui-Folcher, N., Tramier, C., Kainiu, M., Soupé-Gilbert, M.-E., Wijesuriya, K., and Goarant, C.: Hydrological driver for leptospiroses abundance in a small tropical catchment ? Example from the New Caledonian leptospirosis hot-spot, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-1646, https://doi.org/10.5194/egusphere-egu23-1646, 2023.

EGU23-1765 | Orals | HS2.3.2

DNA tracer degradation and adsorption in environmental matrices 

Liping Pang, Laura Heiligenthal, Aruni Premaratne, Kyrin Hanning, Phillip Abraham, Richard Sutton, John Hadfield, and Craig Billington

Synthetic DNA tracers are a promising tool for tracking water contamination pathways. However, quantitative data are lacking on their degradation and adsorption in environmental matrices. Laboratory experiments were conducted to exam the degradation of multiple DNA tracers in stream water, groundwater, and domestic and dairy-shed effluent, and adsorption to stream sediments, soils, coastal sand aquifer media and alluvial sandy gravel aquifer media. The selected DNA tracers were double stranded 302 base pair (bp) and 352 bp in lengths. Their internal amplicons used for qPCR detection were almost the same, but the 352 bp tracers had longer non-amplified flanking regions.

Overall, 352 bp tracer degradation was significantly slower than that of the 302 bp tracers (p = 0.018). Results of thermodynamic analysis indicated that the 352 bp tracers had greater tracer stability. These findings are consistent with our previous field observations that 352 bp tracer reductions were consistently lower than 302 bp tracer reductions in stream water, groundwater, and soils. These findings suggest that longer non-amplified flanking regions may better protect DNA tracers from environmental degradation. In general, the DNA tracers degraded more quickly in the stream water and effluent samples than in the groundwater samples, and fast DNA tracer degradation was associated with high bacterial concentrations.

The two sets of DNA tracers differed little in their adsorption to stream sediment-stream water or aquifer media-groundwater mixtures (p > 0.067). However, the 352 bp tracers adsorbed significantly less to soil-effluent mixtures than the 302 bp tracers (p = 0.005). Compared to their adsorption to the aquifer media-groundwater and stream sediment-stream water mixtures, DNA tracer adsorption to soil-effluent mixtures was relatively less. A plausible explanation is that DNA tracers may compete with like-charged organic matter for adsorption sites, thus were less adsorbed to environmental media in the presence of organic matter.

Our study findings provide insights into the fate of DNA tracers in the aquatic environment and may assist with the future design of DNA tracers for environmental studies. The DNA tracer degradation rates established in this study for a range of environmental conditions could be used to inform the design of future field investigations, such as injection concentrations, sampling distances and experimental durations.

How to cite: Pang, L., Heiligenthal, L., Premaratne, A., Hanning, K., Abraham, P., Sutton, R., Hadfield, J., and Billington, C.: DNA tracer degradation and adsorption in environmental matrices, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-1765, https://doi.org/10.5194/egusphere-egu23-1765, 2023.

EGU23-3673 | Posters on site | HS2.3.2

Temporal stability of Escherichia coli and enterococci concentrations in sandy bottom sediment of a Pennsylvania creek 

Yakov Pachepsky, Dana Harriger, Christina Panko Graff, Matthew Stocker, and Jaclyn Smith

Fecal indicator bacteria (FIB), Escherichia coli, and enterococci are used to define regulatory thresholds for microbial water quality of streams and bodies of water and water body waters used for recreation and irrigation. Bottom sediments serve as secondary habitats for FIB that can enter water columns and alter microbial water quality, notwithstanding waste management at surrounding lands. Therefore, monitoring of indicator bacteria in bottom sediments is important. The discovery of persistent spatial patterns of environmental variables has been beneficial in environmental monitoring. Such patterns often termed temporal stability manifestation, helped substantially decrease the number of monitoring locations by estimating the spatial variation across the observation area according to the established spatial patterns. Temporal stability of indicator bacteria concentrations was observed in water columns of streams and ponds but was so far never researched for bottom sediments.

This work aimed to investigate the temporal stability of E. coli and enterococci concentrations along a reach of the Conococheague creek in the  USGS Conococheague-Opequon Subbasin). Three monitoring sites - TP, I81, and SS  were established where the creek collected the surface runoff from the forested headwater, agricultural, and mixed urban and agricultural areas, respectively. Sediment samples were taken collected weekly continuously for three years. FIB concentrations were measured by membrane filter method for E. coli using the mTec agar and enterococci using the mEI agar. The temporal stability was quantified using the mean relative differences (MRD) of concentrations. To obtain the relative differences for each location, the ratios of logarithms of concentration at each location and the average logarithm of concentrations across all locations were decreased by one for each observation time. MRDs were the relative differences for each location averaged over all observation times.

The sediment was sandy. Annual amplitudes of concentrations of both FIB in sediments were about three orders of magnitude in the range from 1 to 7000 colony forming units (g dry weight)-1. The sine function with the maximum in July and minimum in February gave a reasonable approximation of the annual dynamics at all locations over three years. The MRD values were equal to -0.198± 0.023, -0.012±0.019, and 0.210±0.021 for E. coli and -0.160±0.023, 0.000±0.017, and 0.165±0.024 for enterococci (mean standard error) at TP, I81, and SS locations, respectively. When converted to absolute values, concentrations were on average about 60% higher at SS than at I81, and 60% lower at TP than at I81. Values of MRD over warm (April-September) and cold (October-March) seasons followed the same pattern as the above annual values, with the range of MRD slightly larger over the cold season and somewhat smaller over the warm season as compared with the annual values.

Qualitative metrics also indicated the prevalence of specific spatial patterns. In particular, E. coli (enterococci) concentrations at TP, I81, and SS were smaller than at two other sites in 65% (63%),  28%(24%), and 6%(13%)  of observation times, respectively. 

Overall, three years of observations showed that persistent spatial patterns were present and manifested themselves against the backdrop of persistent temporal oscillatory annual patterns.

How to cite: Pachepsky, Y., Harriger, D., Panko Graff, C., Stocker, M., and Smith, J.: Temporal stability of Escherichia coli and enterococci concentrations in sandy bottom sediment of a Pennsylvania creek, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-3673, https://doi.org/10.5194/egusphere-egu23-3673, 2023.

EGU23-3691 | Posters on site | HS2.3.2

Occurence of selected hydroxy derivatives of polycyclic aromatic hydrocarbons in wastewater treatment plant 

Katarzyna Styszko, Justyna Pamuła, Elżbieta Sochacka-Tatara, and Agnieszka Pac

Evidence of the causal-empirical link between man-made chemicals present in industrial and household products, often leakage into the environment, and the effects on public health is growing, although still limited. These include, among other things, air pollutants in the environment associated with the highest prevalence of asthma, as well as respiratory and cardiovascular diseases in urban populations. There is strong evidence of health risks posed by human exposure to organic air pollutants such as PAH (polycyclic aromatic hydrocarbons) from combustion processes (solid fuels, coal and biomass) and communication. Generally, PAHs are formed during incomplete combustion and pyrolysis of organic material in a wide range of temperatures, up to over 1200 ° C. After entering the body, PAHs are transported to the alveoli and then spread throughout the body with the blood. The biological effects that PAHs cause in the human body are short-term, chronic, or long-term health effects, i.e. carcinogenicity, immunotoxicity, or developmental toxicity, genotoxicity. After entering the human body, PAHs undergo a complicated metabolism process and are excreted in the form of OH-PAHs with urine and faeces.

The purpose of the study was to analyse selected OH-PAHs in influent and effluent wastewater from the wastewater treatment plant (WWTP). Analysed PAH metabolites are: 1- and 2-hydroxynaphthalene, 2- and 9-hydroxyfluorene, 9-hydroxyphenenthrene, 1-hydroxypyrene, and 3-hydroxybenzo(a)pyrene. The wastewater samples came from the largest WWTP in Kraków. OH-PAH concentration levels were determined by gas chromatography with mass spectrometry (GC-MS), preceded by the extraction of analytes into the solid phase and their derivatization.

The concentrations of the analyzed compounds were at the level of ng/L. Regardless of the season of sampling for analysis (summer and winter), the highest concentrations, even up to 400 ng/L, were found in 2-hydroxynaphthalene and 9-hydroxyfluorene in influents. 1-hydroxypyrene, which according to literature reports is considered a marker of exposure to PAHs, was observed for influent and effluent samples only in winter at the level of only a few ng/L.

 

Keywords: Hydroxy derivatives of polycyclic aromatic hydrocarbons, Biomarker, Wastewater

Acknowledgments: A Research project financed by program “Initiative for Excellence – Research University” for the AGH University of Science and Technology. The research was supported  by Research Subsidy AGH 16.16.210.476.

How to cite: Styszko, K., Pamuła, J., Sochacka-Tatara, E., and Pac, A.: Occurence of selected hydroxy derivatives of polycyclic aromatic hydrocarbons in wastewater treatment plant, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-3691, https://doi.org/10.5194/egusphere-egu23-3691, 2023.

EGU23-4369 | ECS | Orals | HS2.3.2

Navigating the Danube: A data-driven approach to evaluate the impact of inland shipping on faecal pollution 

Ahmad Ameen, Sophia D. Steinbacher, David Lun, Gerhard Lindner, Julia Derx, Regina Sommer, Katalin Demeter, Rita Linke, Günter Blöschl, Alfred P. Blaschke, Alexander K. T. Kirschner, and Andreas H. Farnleitner

Introduction: Inland navigation has seen explosive growth over the past few decades, leading to increasing concerns about its environmental and health impacts. Coastal waters are usually monitored for wastewater contamination by maritime traffic, but little is known about faecal pollution caused by the inland waterways transport in large rivers. The Danube River in Europe is a very popular destination for cruise ship trips. The extent to which the faecal pollution in the Danube is caused by shipping traffic in general and the growing number of cruise ships specifically is still largely unknown. The Danube River Information Service (DoRIS) has been established to track ship traffic and provide data for monitoring in Austria. This database allows the estimation of the faecal pollution potential of ships with a high level of spatial and temporal resolution for the first time.

Methodology: An approach was developed to investigate the potential contribution of various ship categories to faecal pollution in the Danube River (Lower Austria) by combining water quality monitoring data with ship traffic data. The ship traffic data was extracted from DoRIS using a Python-based programming language code and sorted into three categories (cruise, passenger, and freight ships). Water quality monitoring was conducted at 11 transects along a 223-kilometre Danube River reach in Lower Austria. In collaboration with local authorities, each river transect was sampled at 5 points across the profile for one year at monthly intervals. The faecal indicator bacterium E. coli along with physio-chemical water quality parameters was analyzed for all samples. Theoretical faecal impact scenarios were developed using data on average daily ship traffic and factors such as ship type, onboard wastewater treatment facilities, onboard passenger capacity, and seasonal fluctuations of cruise tourism. To evaluate the influence of local and regional shipping traffic on the faecal pollution dynamics, a statistical correlation analysis was performed using data from the entire river reach and ship berthing stations.

Results: The faecal impact scenario analysis, revealed that the shipping industry had the same degree of maximum pollution potential as treated municipal wastewater. In case of improper onboard wastewater treatment, faecal pollution can be substantial. According to water quality monitoring, 94% of the samples had low to moderate faecal pollution, while none were classified as high. As a result, no significant increase in E. coli concentrations was detected throughout the 223 km long river stretch. However, at one of the 11 river transects, significant variations in the E. coli concentration were detected. After conducting a correlation analysis using statistical parameters for the whole river reach, we found no significant correlation between E. coli concentrations and any of the investigated ship counting metrics or ship types. Nonetheless, E. coli concentration was found to be significantly higher at one of the cruise ship berthing stations.

Acknowledgement: The research was funded by Amt der Niederösterreichischen Landesregierung, Abteilung Wasserwirtschaft (WA2) and the GFF Niederösterreich mbH (LS19-016 Future Danube). We would like to thank collaboration partners from the government of Lower Austria and the Austrian shipping inspectorate.

How to cite: Ameen, A., Steinbacher, S. D., Lun, D., Lindner, G., Derx, J., Sommer, R., Demeter, K., Linke, R., Blöschl, G., Blaschke, A. P., Kirschner, A. K. T., and Farnleitner, A. H.: Navigating the Danube: A data-driven approach to evaluate the impact of inland shipping on faecal pollution, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-4369, https://doi.org/10.5194/egusphere-egu23-4369, 2023.

EGU23-4946 | ECS | Orals | HS2.3.2

Risk assessment of waterborne virus in Lake Geneva: the present and the future 

Chaojie Li, Émile Sylvestre, Tim Julian, and Tamar Kohn

The presence of waterborne enteric viruses in lake recreational water sites is not desired, as they may have a negative impact on human health. However, their concentrations, fate and transport in lakes remain poor understood. To date, the health risks posed by enteric viruses in surface water was typically assessed via monitoring of fecal indicators, such as E. coli, whereas a direct assessment of fate and transport of waterborne viruses is less common. In this study, we propose a coupled water quality and quantitative microbial risk assessment (QMRA) model to study the transport, fate and infection risk of four common enteric viruses, using Lake Geneva as a study site. The measured virus load in raw sewage entering the lake was characterized, fitted with different distributions and then used as the source term in the water quality simulations. A Eulerian transport model was employed to model virus transport while considering spatially and temporally varying inactivation of viruses. Eventually, the probability of infection was quantified by linking the virus concentrations at a popular beach with QMRA. The model framework was then applied to model current situations as well as future scenarios under climate change. In the simulations of year 2019, it was found that environmental stressors noticeably reduce the infection probability exerted by viruses with low background inactivation in summer, but effects in the winter are minor. Norovirus appeared to be the most abundant species and also led to the highest infection probability, which was at least 10 times greater than that of the other viruses studied. In addition, the model highlighted the role of the wind field in conveying the contamination plume and hence in determining infection probability. The simulations for the future revealed an increase of virus inactivation rates in summer times due to higher water temperature as well as increased radiation levels due to reduced cloud coverage. The enhanced inactivation in summer could compensate for the higher virus loading caused by population growth. In contrast, in winter minor temperature changes and inconsequential radiation variation would not offset the increased virus loading. However, even in the winter cases the future infection risks would not undergo significant change compared with the current situation.  The proposed model framework is flexible and could be relatively easily refined and adapted for other locations and scenarios. This study highlights the potential of combining water quality simulation and virus-specific risk assessment for a safe water resources usage and management.

How to cite: Li, C., Sylvestre, É., Julian, T., and Kohn, T.: Risk assessment of waterborne virus in Lake Geneva: the present and the future, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-4946, https://doi.org/10.5194/egusphere-egu23-4946, 2023.

EGU23-5660 | Orals | HS2.3.2 | Highlight

Regional Scale Modelling of Pharmaceutical Pollution in Rivers by Integrating Rural and Urban Sources 

Francesco Bregoli, Leo Posthuma, Nikola Rakonjac, Caterina Zillien, Peter Vermeiren, Erwin Roex, Sjoerd van der Zee, Erwin Meijers, and Ad Ragas

Contaminants of emerging concern (CECs) can threaten aquatic ecosystems and human health. Both rural and urban areas are main sources of CECs to the environment. In rural areas, veterinary pharmaceuticals (VPs) are used to prevent diseases and protect the health of farm animals. The excrements of medicated animals are spread as manure to agricultural lands, where, after rainfall, VPs can be mobilized and reach surface waters through runoff. In urban areas, pharmaceuticals excreted by humans are collected in sewage systems and are only partially removed in wastewater treatment plants (WWTPs). Eventually, pharmaceuticals can reach surface waters through discharge of WWTP effluent. Currently, most of the predictive models only consider one source type, e.g. WWTPs or agricultural land. This limits their prediction performance since many CECs are being emitted by multiple source types. Therefore, the aim of this study is to integrate urban and rural sources of CECs in one regional water quality assessment.

Here, we predicted the concentration of CECs in the Eem river basin, the Netherlands, given land-use data combined with hydrological modeling. This allows for integrated evaluation of rural and urban emissions. These emissions were predicted with models developed within the context of the SUSPECt project (https://cec-partnership.nl/web/index.php/projects/suspect). CECs exposures were predicted with the Dutch National Water Quality Model where WWTPs emissions were included as point sources and rural emissions as diffuse sources. The temporal resolution of the model hydrology is seasonal. This is key to analyze the temporal variation of concentration due to manuring of agricultural lands which mainly occurs in Spring.

Predicted concentrations were successfully compared to measured concentrations taken in the SUSPECt project and from the database of the KIWK project (www.kennisimpulswaterkwaliteit.nl) for 6 compounds: carbamazepine and fipronil (only urban sources) and trimethoprim, sulfamethoxazole, permethrin and dexamethasone (urban and rural sources).

How to cite: Bregoli, F., Posthuma, L., Rakonjac, N., Zillien, C., Vermeiren, P., Roex, E., van der Zee, S., Meijers, E., and Ragas, A.: Regional Scale Modelling of Pharmaceutical Pollution in Rivers by Integrating Rural and Urban Sources, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-5660, https://doi.org/10.5194/egusphere-egu23-5660, 2023.

EGU23-7060 | ECS | Orals | HS2.3.2

Estimating Pathogen Removal in Bank Filtration – A Methodology for the Construction of Surrogate Models to Assist Decision Making 

Dustin Knabe, Aronne Dell'Oca, Alberto Guadagnini, Monica Riva, and Irina Engelhardt

Induced bank filtration is a known method for sustainable drinking water production in regions with limited groundwater resources. However, this method is at risk from surface water contaminations, e.g., by pathogens. Numerical models simulating pathogen fate in groundwater are typically too complex to be used as standard tools by waterworks managers or environmental agencies. To mitigate this problem, we present a methodology for the construction of easy-to-use reduced order models as surrogates for complex numerical reactive transport models for pathogens and pathogen indicators in induced bank filtration.

First, a streamlined one-dimensional numerical model was set up for the reactive transport of pathogens and pathogen indicators in induced bank filtration. Processes in the model include advection-dispersion, inactivation, attachment to and detachment from the sediment as well as straining and the presence of a clogging layer. Model parameters are divided into two groups: Group A includes site specific parameters for which values are typically available (with limited uncertainty) for management- and engineer-level users (e.g., grain size, distance of extraction well to the river); Group B includes process parameters which are typically affected by high uncertainty (e.g., inactivation and detachment coefficients).

We rely on an extensive dataset for coliforms and somatic coliphages collected over a 16-month period at an active induced bank filtration site. Stochastic inversion is used to assess uncertainty for model parameters of Group B (constrained on the dataset), while those of Group A are set to the values of the specific site. Principal component analysis (PCA) is applied to reduce the dimensionality of model parameter space and correlation amongst the uncertain parameters of Group B. A surrogate model is then constructed through generalized polynomial chaos expansion (gPCE). In this, the value range of Group A parameters is based on typical scenarios for induced bank filtration sites, while the range of the PCA-reduced Group B parameters is set to the uncertainty identified in the stochastic inversion.

The surrogate model allows to evaluate, at significantly reduced computational cost, the removal of coliforms and somatic coliphages in induced bank filtration based on user-defined values for parameters of Group A, but also including the uncertainty stemming from parameters of Group B. The surrogate model estimates for removal are in good agreement with observed removals for coliforms and somatic coliphages at the monitored site and with other (albeit limited) datasets from induced bank filtration sites found in the published literature. At this stage, the obtained surrogate model can be considered as a prototype. The assessment of its full potential requires additional extensive validation against other field sites. In general, surrogate models together with the overall methodological framework we propose, can be seen as a promising tool to assist informed decisions about pathogen transport at induced bank filtration sites.

How to cite: Knabe, D., Dell'Oca, A., Guadagnini, A., Riva, M., and Engelhardt, I.: Estimating Pathogen Removal in Bank Filtration – A Methodology for the Construction of Surrogate Models to Assist Decision Making, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-7060, https://doi.org/10.5194/egusphere-egu23-7060, 2023.

EGU23-7243 | ECS | Posters on site | HS2.3.2

Quantifying in-situ decay-rates of faecal indicators and pathogenic viruses in a river section in Germany. 

Malte Zamzow, Wolfgang Seise, Hans-Christoph Selinka, and Frank Schumacher

For assessing the health risk at recreational waters resulting from wastewater discharges from urban catchments, knowledge about the dynamics of the ratio between faecal indicator bacteria and pathogenic viruses is essential. Differences in wastewater concentrations, decay rates, and relevant exposure concentrations may influence how reliable concentrations of faecal indicator bacteria truly reflect existing health risk. Full-scale experiments on decay rates of pathogenic viruses in natural surface waters, especially fresh waters, are largely missing.

In the present study, we quantified the decay rates of faecal indicator bacteria and pathogenic viruses in a natural surface water. To this end, we performed two Lagrangian sampling campaigns after combined sewer overflows (CSO) along a river section in Berlin, Germany. During the campaigns the same body of contaminated water was resampled while travelling through the city. Organic micro-pollutants (Gabapentine, Acesulfame), and inorganic ions (Cl-, SO42-) were analysed to function as conservative tracer substances. Wastewater and stormwater amounts were estimated in each sample. Furthermore, all samples were analysed for humane Norovirus GII, Adenovirus 40/41, somatic coliphages, f-specifc coliphages, intestinale enterococci, and E.coli. Decay rates were derived by relating the pathogens to the estimated fraction of wastewater. The observation time was 5 and 2 days for the first and second CSO event, depending on the flow of the river. Decay rates indicate a significant variability between organisms but also between sampling campaigns as a result of different physical-chemical conditions. While the oxygen was completely consumed in the wastewater plume of the first event, this was not the case during the second event, which still allowed pathogen removal by grazing of heterotrophic zooplankton. Our results contribute to the general understanding of pathogens and faecal indicators in surface waters.

How to cite: Zamzow, M., Seise, W., Selinka, H.-C., and Schumacher, F.: Quantifying in-situ decay-rates of faecal indicators and pathogenic viruses in a river section in Germany., EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-7243, https://doi.org/10.5194/egusphere-egu23-7243, 2023.

EGU23-7290 | Orals | HS2.3.2

Coupling targeted monitoring, pathway-oriented data intensive modelling and fate process-based modelling to estimate emission loads and concentrations of trace pollutants in the Danube River Basin 

Ottavia Zoboli, Marianne Bertine Broer, Oliver Gabriel, Jos van Gils, Sibren Loos, Steffen Kittlaus, and Matthias Zessner

The number of trace pollutants released by anthropogenic activities is increasing exponentially, their distribution in the environment is often ubiquitous and tracking their fate in river systems via monitoring would require a prohibitive financial effort due to high analytical costs. In this context, models are an irreplaceable tool to identify and quantify emissions loads and to estimate concentration levels in unmonitored catchments. Within the Interreg project Danube Hazard m3c, a novel combined approach has been applied in the Danube River Basin. Firstly, the pathway-oriented MoRE model (Modeling of Regionalized Emissions) was applied at the mesoscale in seven largely diverse river catchments (sub catchments of 40-650 km2) located in four different countries. This semi-empirical and relatively data intensive model could be robustly applied thanks to a rarely available data basis, which was achieved via a targeted and harmonized measurement campaign carried out in multiple environmental and engineered compartments for selected trace pollutants representative of larger groups of substances with comparable patterns of diffuse and point emissions, namely agricultural biocides, industrial chemicals, pharmaceuticals and contaminants of both natural and anthropogenic origin. The high parametrization efforts of the MoRE model yield a quite accurate analysis of emission pathways (e.g. wastewater treatment plant discharges, groundwater and interflow, soil erosion) and estimation of contaminants concentration in the rivers. In a second step, the system understanding gained through MoRE was utilized to improve the performance of the DHSM (Danube Hazardous Substance Model, based on the EU SOLUTIONS model), also applied in the same seven catchments for comparison. This second tool is a source-oriented fate process-based model, with only limited regional data requirements (primarily hydrological data) and which thus requires a much easier parametrization. The parallel application of the two models in the test catchments revealed major differences in the identification of emission pathways, e.g. diffuse emissions of industrial chemicals (PFOS and PFOA) and pharmaceuticals, and in the estimation of emission loads of metals from hotspots, e.g. from mining sites. As last step, the improved version of DHSM was applied to the whole Danube River Basin to quantify the relevance of different sources and pathways of emissions for the selected indicator contaminants and to estimate the risk of exceedance of the environmental quality standards in unmonitored surface water bodies. An early application of the DHSM for 17 target contaminants revealed Danube River Basin-wide emissions ranging between 0.1 and about 4,000 tonnes per year, with the share of point sources ranging between < 1% to >95%. This contribution focuses on the enhanced system understanding and improved modelling performance gained through the novel combined application of both approaches and will include final updated and validated basin-wide emission estimates.

How to cite: Zoboli, O., Broer, M. B., Gabriel, O., van Gils, J., Loos, S., Kittlaus, S., and Zessner, M.: Coupling targeted monitoring, pathway-oriented data intensive modelling and fate process-based modelling to estimate emission loads and concentrations of trace pollutants in the Danube River Basin, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-7290, https://doi.org/10.5194/egusphere-egu23-7290, 2023.

EGU23-7592 | ECS | Posters virtual | HS2.3.2

The fate of urease inhibitors in two agricultural soils 

Sophia Schmalhorst, Sandra Kühn, Martin Kaupenjohann, and Sondra Klitzke

Urease inhibitors (UI) are organic trace substances, which are applied along with urea fertilizers to reduce NH3 emissions from agricultural fields. Due to the recent amendment to the German fertilizer act (DüngG) which now dictates the use of UI, increasing amounts of these substances will be applied to arable soils.  So far, little is known about the fate of UI in soils and there is only few data on the leaching of UI from soil to groundwater, especially with respect to field data. However, first studies have proven traces of UI in surface and ground waters, raising concern among drinking water suppliers. Therefore, the aim of this study was to investigate the fate of two different UI, i.e. N-(2-Nitrophenyl) phosphoric acid triamide (2-NPT) and N-(n-Butyl)thio-phosphoric triamide (NBPT) in two agricultural soils, addressing the following questions:

  • How long do UI remain in the topsoil following application?
  • Which portion will be translocated to deeper soil layers?

 

On two agriculturally used fields in the state of Brandenburg (Germany) with sandy soils, which differ in their topsoil total carbon concentration (Berge 0.96 %, Ribbeck 1.39 %) and pH (Berge 5.9, Ribbeck 7.6), 2-NPT (as urea prills) and NBPT (as a mixture with urea solution) were applied along with urea. Soil samples were taken from the topsoil at 0-5 cm depth (using a soil sampling ring with a volume of 100 cm³) and from 5-15 cm and 15-30 cm depth (using a Pürckhauer sampler) of 4 different plots each prior to the application of the substances. Afterwards, samples from the topsoil were taken 1, 3, 6, 8, 10, 12, 14 and 21 days following the application. On the last day of the sampling period, samples from 5-15 cm and 15-30 cm depth were taken in addition. Samples were stored at -18°C until analysis.

Based on recovery tests by spiking the study soils with UI, the field-moist samples (sieved to 2 mm) were extracted according to the following procedure: 20 ml extraction solution (50 Vol.-% Acetonitrile/50 Vol.-% H20 for 2-NPT and 0.1 M KCl for NBPT) were added to 10 g soil, then shaken on a horizontal shaker (30 min, 120 rpm). After centrifugation (30 min, 3830 g), the supernatant was filtered through cellulose acetate filters (0.45 µm) and transferred to vials. The extracts were adjusted to neutral pH using dilute NaOH solution and stored in the refrigerator until measurement by HPLC-MS.

The concentration on 1 day of 2-NPT in the Berge topsoil amounted to 353 ± 151 µg/kg and in the Ribbeck topsoil 302 ± 148 µg/kg. NBPT was not found in any of the two soils. Whilst 2-NPT was no longer detectable in the Ribbeck topsoil after 10 days, 2-NPT decreased much slower in the Berge topsoil, reaching concentrations of 15.4 ± 15.7 µg/kg after 21 days. None of the inhibitors could be detected in deeper soil layers. Results will be discussed in the context of the site-specific soil parameters and the local precipitation data.

How to cite: Schmalhorst, S., Kühn, S., Kaupenjohann, M., and Klitzke, S.: The fate of urease inhibitors in two agricultural soils, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-7592, https://doi.org/10.5194/egusphere-egu23-7592, 2023.

Natural and constructed wetlands are now frequently used across the United States for mitigating nitrate losses to both surface and groundwater. Though the use of wetlands as a treatment approach for nitrate in runoff is well known, other active contaminants regularly co-occur with nitrate, potentially affecting the efficacy of nitrate-N removal. For example, veterinary pharmaceuticals have been observed in runoff originating from fields that receive livestock facility animal waste. In 2022, two mesocosm experiments were conducted to evaluate the combined effects of 4 common-use veterinary antibiotics (VAs) (chlortetracycline, sulfamethazine, lincomycin, monensin) on nitrate-N reduction efficiency. We hypothesized veterinary antibiotics would significantly impact nitrate-N removal through changes in denitrification processes within wetland ecosystems. To test this hypothesis, we simulated two pulse-flow storm events (2.5mg N03-N/L, 7.5 mg N03-N/L) and quantified the combined effects of trace-level antibiotics (1.0 mg/L) on the nitrogen cycle in fully saturated treatment wetlands. Results from previous experiments we conducted suggest nitrate reduction rates in treatments receiving antibiotics (CA= -1.04, FTWA= -1.31) remove nitrate more efficiently than those without (C= -0.01, FTW= -0.52). Plant uptake of VAs was also assessed, with results indicating that accumulation of VA compounds in wetland plants occurs and is primarily limited to the below ground biomass (Above ground= 0.59mg per plant, Below ground=206.66mg per plant) and the antibiotic species. Findings from these experiments will provide new insight into whether antibiotic residues in wetland environments affect proposed mitigation strategies for controlling nitrogen losses from fertilized crops and managing nitrate contamination of ground and surface water.

How to cite: Russell, M.: Assessing the impact of Veterinary Antibiotic species on Treatment Wetland Nutrient Removal at the Mesocosm Scale, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-8135, https://doi.org/10.5194/egusphere-egu23-8135, 2023.

Irrigation ponds provide a substantial amount of water for crop production.  An increasingly large body of evidence has linked microbial impairment of these resources to foodborne outbreaks. Therefore, monitoring the microbial quality of irrigation ponds is especially prudent for food safety and reducing the incidences of illnesses and deaths resulting from contamination events. Escherichia coli (E. coli) is used worldwide as an indicator for microbial contamination of water resources as concentrations are usually indicative of pathogen presence and/or cases of illnesses.

Algae and cyanobacteria (collectively henceforth referred to as phytoplankton can comprise large fractions of the overall biomass in waterbodies. Phytoplankton are important in water quality monitoring because they directly affect water quality metrics such as dissolved oxygen and pH as well as potentially producing toxic compounds. The interaction between E. coli concentrations and phytoplankton in environmental waters has received relatively little attention and has not been studied in ponds providing water for irrigation. The objective of this work was to see if phytoplankton can be used as predictors of E. coli concentrations in irrigation ponds.

Two irrigation ponds in Maryland, USA were sampled and sensed eleven times on the permanent spatial grid during the 2017 and 2018 growing seasons. A YSI sonde was used to measure water quality variable (WQV) concentrations of pH, dissolved oxygen (DO), specific conductance (SPC), temperature(C) , turbidity (NTU), phycocyanin, Chlorophyll a (CHL),and dissolved organic matter (FDOM). Total carbon (TC), and total nitrogen (TN) were measured in the laboratory. Phytoplankton functional groups (PFG) were green algae, diatoms, cyanobacteria, and dinoflagellates. Identification and enumeration of PFG was performed with laboratory microscopy.  The random forest (RF) algorithm was used to predict E. coli concentrations and rank variables by importance using three predictor sets including water quality variables (WQV)+PFG, PFG only, and WQV only on the 2017, 2018, and 2017+2018 datasets.

For both ponds, the WQV predictor set alone provided the best model performance metric results (R2= 0.671 and 0.812, and RMSE= 0.321 and 0.374 log concentrations for Ponds 1 and 2, respectively). The combined phytoplankton and WQV predictor sets provided very close results to the WQV results alone and in all the phytoplankton variables alone as predictors showed the worst performance. The top predictors in the PFG+WQV for Pond 1 were CHL, TN, pH, NTU, and FDOM which was similar to the WQV only set. Flagellates ranked among the most important predictors in the PFG+WQV (6th) and PFG predictor sets (1st). In Pond 2, the top predictors in the PFG+WQV were TC, C, pH, DO, and TN. Diatoms were found to be the leading predictor in the PFG-only dataset in Pond 2.

Results of this work indicate that in studies of water bodies the effect of phytoplankton on E. coli concentrations is well represented by the water quality variables, and concentrations of the phytoplankton groups per se do not add information for improvement of the prediction of microbial water quality evaluated by E. coli concentrations using the usually very efficient machine learning predictive random forest algorithm.  

How to cite: Stocker, M., Smith, J., and Pachepsky, Y.: Can data on major phytoplankton functional group concentrations improve the estimation of E. coli concentrations in agricultural pond waters?, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-8294, https://doi.org/10.5194/egusphere-egu23-8294, 2023.

EGU23-8436 | Posters virtual | HS2.3.2

Spatiotemporal variability of microcystin concentrations in water of an irrigation pond in Maryland, USA 

Jaclyn Smith, Matthew Stocker, and Yakov Pachepsky

Cyanotoxins in agricultural irrigation waters pose a potential human and animal health risk. Cyanotoxins can be transported to crops and soil during irrigation where they can remain in the soils for extended periods and be absorbed by root systems. While studies have reported spatial and temporal distributions for cyanotoxins in various freshwater sources, little has been reported for agricultural irrigation ponds. This research aimed to determine if persistent spatial and temporal patterns of the cyanotoxin microcystin occur in agricultural irrigation ponds. The study was performed at a working irrigation pond in Maryland, USA, during the 2022 summer sampling campaign consisting of 6 sampling dates over a fixed spatial 10-location grid. Concentrations of microcystin were determined using ELISA microcystin-ADDA kits. Ten water quality parameters were obtained using fluorometry and in-situ sensing. Relative differences (RDs) between a sampling location’s microcystin concentration and average concentrations across the pond were computed for each sampling date. Mean relative differences (MRDs) were computed for each sampling location for all sampling dates. Positive (negative) MRDs were found in locations where concentrations were predominantly larger (smaller) than the pond’s average. Persistent spatial patterns of microcystin concentrations were established. The pond’s flow conditions and bank proximity to sample locations were indicative of the MRD values signs and amplitude. The highest absolute values of the Spearman correlation coefficients were found between microcystin and pH (-0.777), and microcystin and phycocyanin (0.669). The lowest absolute values for correlation coefficients were found for colored dissolved organic matter (0.226) and chlorophyll-a (0.289). Correlations between microcystin relative differences and water quality relative differences were generally low and not statistically significant. Results of this work show that microcystin concentrations can exhibit stable spatial and temporal patterns in irrigation ponds, indicating that water quality sampling for cyanotoxins and placement of water intake should not be arbitrary. Research of the spatiotemporal organization of other cyanotoxin concentrations as well as understanding the degree of site-specificity of cyanotoxin concentration relationships with water quality parameters presents an interesting research avenue.

How to cite: Smith, J., Stocker, M., and Pachepsky, Y.: Spatiotemporal variability of microcystin concentrations in water of an irrigation pond in Maryland, USA, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-8436, https://doi.org/10.5194/egusphere-egu23-8436, 2023.

EGU23-9942 | ECS | Orals | HS2.3.2

The fate of nitrification and urease inhibitors in simulated bank filtration 

Muhammad Zeeshan, Marco Scheurer, Christina Förster, Christine Kuebeck, Aki Sebastian Ruhl, and Sondra Klitzke

Nitrification and urease inhibitors (NUI) are used in conjunction with nitrogen (N) fertilizers on agricultural soils to improve the efficiency of N fertilizers and reduce the emission of greenhouse gases. After application, NUI might transfer to aquatic environments through leaching or surface runoff. Nowadays, NUI such as 1,2,4-triazole, 3,4-dimethylpyrazole (3,4-DMPP) and dicyandiamide (DCD) are frequently found in surface waters with concentrations in the magnitude of µg/L. The fate of NUI in bank filtration (BF) is currently poorly known. BF is a sustainable water treatment system providing high quality water by efficiently removing numerous organic micropollutants from the source water. Herein, sorption and degradation of NUI in simulated BF under near-natural conditions was investigated. Besides, the effect of NUI on the microbial biomass of slowly growing microorganisms and the role of microbial biomass on NUI removal was investigated. Duplicate sand columns (length 1.7 m), fed with surface water were spiked with a pulse consisting of four nitrification (1,2,4-triazole, DCD, 3,4-DMPP and 3-methylpyrazole) and two urease inhibitors (n-butyl-thiophosphoric acid triamide and n-(2-nitrophenyl) phosphoric triamide). The average spiking concentration of each NUI was 5 µg/L. The flow velocity was adjusted to 0.2 m/d. Breakthrough curves of tracer (sodium chloride) and the NUI appeared at same time; therefore, sorption may be ruled out. Additionally, experimental and modeled breakthrough curves of NUI suggested no retardation for any of the inhibitors. Therefore, biodegradation was identified as the main elimination pathway for all substances and was highest in zones of high microbial biomass. N-butyl-thiophosphoric acid triamide was completely removed within a hydraulic retention time (HRT) of 24 hours and proved to be a highly degradable substance. Nitrification inhibitors showed 50% mass recovery (except for 3,4-DMPP) after an HRT of 4 days. A slight effect of NUI on microbial biomass was observed. This study highlights that hydraulic retention time and microbial biomass are key indicators for the degradation of NUI.

How to cite: Zeeshan, M., Scheurer, M., Förster, C., Kuebeck, C., Ruhl, A. S., and Klitzke, S.: The fate of nitrification and urease inhibitors in simulated bank filtration, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-9942, https://doi.org/10.5194/egusphere-egu23-9942, 2023.

EGU23-10140 | Orals | HS2.3.2

Understanding the impacts of dogs and birds on faecal pollution of bathing waters in Dublin Bay 

Guanghai Gao, John O'Sullivan, Aisling Corkery, Liam Reynolds, Niamh Martin, Laura Sala-Comorera Sala-Comorera, Gregory O’Hare, and Wim Meijer

Dublin Bay is a shallow bay located on the east coast of Ireland in Irish Sea. The water body is bounded to the west by Dublin City and to the east by the Irish Sea, with its northern and southern extents being defined by Howth Head and Dalky, respectively.  The southern side of the Bay includes the designated bathing waters of Sandymount Strand and the non-designated (but monitored) bathing waters of Merrion Strand. The water quality of these bathing areas remains vulnerable to numerous microbial pollution inputs, and these continue to present risks to recreational and economic activities that underpin much of the ecosystem service provision in the area, particularly during the bathing water that extends from June to September each year. Microbial pollutants are known to derive from agricultural diffuse sources in upland catchments and from point discharges from the wastewater drainage network, specifically during wet weather events when combined sewer overflows (CSOs) are active.  However, while accepted as being problematic in the overall pollution ‘mix’, concentrations of faecal indicator bacteria (FIB) from the faeces of dogs (dog fouling) and from local bird communities are less well understood – Dublin Bay was designated a 'biosphere reserve' by UNESCO in 2015 and remains home to numerous species of seabirds, many of which are present in internationally important numbers.

Here we present an assessment of the significance of FIB inputs from dogs and birds in their contribution to total faecal pollution in Dublin Bay.  The extent of dog fouling was assessed through five daily ‘beach sweeps’ on both Sandymount and Merrion Strands from 2019 to 2021. Eighty-one dog fouling events (30 and 51 on Sandymount and Merrion Strands, respectively) were observed, equating to an average of six fouling ‘events’ per day at Sandymount and 10 ‘events’ per day at Merrion. Laboratory testing was undertaken to determine average Escherichia coli (E. coli) and enterococci concentrations in the dog faeces.  BirdWatch Ireland (an independent bird protection organisation in Ireland) data from the Dublin Bay Birds Project (2013 to 2016) was used to quantify E. Coli and enterococci pollution loadings to Dublin Bay bathing waters deriving from the presence of both migratory and non-migratory bird populations during the bathing water season.

A coupled hydrodynamic and water quality model was integrated with sediment-bacteria interaction model which was further developed to simulate the inputs from dogs and birds. The model was then calibrated and validated with extensive water quality and ADCP (current speed and direction) measurements collected in nearshore areas around Dublin Bay to simulate the transport and fate of FIB in the study area.  The model included the freshwater (river) inputs carrying diffuse agricultural pollutants to the Bay, and the known point source pollution releases from within wastewater drainage network.  A dynamic decay rate, which included the effects of  temperature and light intensity was included in the model.

This research (Acclimatize) was part funded by the European Regional Development Fund through the Ireland Wales Cooperation Programme.

How to cite: Gao, G., O'Sullivan, J., Corkery, A., Reynolds, L., Martin, N., Sala-Comorera, L. S.-C., O’Hare, G., and Meijer, W.: Understanding the impacts of dogs and birds on faecal pollution of bathing waters in Dublin Bay, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-10140, https://doi.org/10.5194/egusphere-egu23-10140, 2023.

EGU23-10824 | Orals | HS2.3.2

Wildfire Threats to Groundwater Supplies: Implications for Pathogen and Particulate Contaminant Transport in Porous Media 

Monica Emelko, Omar Chowdhury, Xiaohui Sun, Allie Kennington, Philip Schmidt, Uldis Silins, and Micheal Stone

Climate change-associated wildfires are increasing in frequency and severity, causing increasingly variable or deteriorated water quality, and challenging in-plant treatment processes beyond design and operational response capacities, to the point of service disruptions. Recent work has shown that the wildfire impacts on drinking water treatability can extend far downstream and be long-lasting. Notably, very little information regarding the impacts of severe wildfire on groundwater supplies is currently available.

Wildfire transforms fuels (i.e. biomass, soil organic matter). Pyrogenic carbonaceous material formed after wildfire includes particulate ash and biochar, which often contains toxic polyaromatic hydrocarbons, dioxins and furans, as well as some heavy metals. These mobile materials may be incorporated into soil profiles (change the soil properties, e.g., hydrophobicity, pH), redistributed, or removed from a burned site by wind and water erosion to source water. While surface water treatment technologies may have some capacity to remove these contaminants from surface water, the subsurface fate and mobility of these toxic particles has not been documented and is not understood. Moreover, the implications of potential changes in dissolved organic carbon on pathogen transport in these systems has not been documented. Because groundwater-based drinking water supplies do not typically require treatment beyond disinfection, it is possible that contaminated particles could enter drinking water wells after wildfire. Moreover, NOM-associated changes in water quality may increase the risk of pathogen transport through the subsurface.

Here, the impacts of wildfire on the transport E. coli and Cryptosporidium parvum oocysts in various porous media environments (e.g., particle properties, solution chemistry, organic matter character) were evaluated. Column tests were conducted using laboratory prepared wildfire ash-impacted water and wildfire impacted surface water collected after the 2017 Kenow Wildfire in Waterton, Alberta, Canada. These investigation demonstrate that under certain conditions potential post-fire shifts in water quality can substantially enhance particle/microbe transport in porous media, thereby underscoring the need to evaluate microbial risks to groundwater supplies after severe wildfire.

How to cite: Emelko, M., Chowdhury, O., Sun, X., Kennington, A., Schmidt, P., Silins, U., and Stone, M.: Wildfire Threats to Groundwater Supplies: Implications for Pathogen and Particulate Contaminant Transport in Porous Media, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-10824, https://doi.org/10.5194/egusphere-egu23-10824, 2023.

EGU23-11053 | Orals | HS2.3.2

Protection of groundwater against microbial contamination 

Jack Schijven, Harold van den Berg, and Saskia Rutjes

A novel microbial risk analysis of groundwater as part of the Dutch guideline document for Quantitative Microbial Risk Assessment (QMRA) of drinking water consumption encompasses 1) vulnerability assessment of groundwater production sites, 2) calculating the protection zone against microbial contamination to remain below an infection risk of 1/10,000 persons/year, 3)  assessment of contamination sources within the protection zone, and 4) QMRA for identified contamination sources. Protection zones are based on a standard virus contamination scenario and may be computed using a required minimal travel time, a hydrological model that includes a first order decay term for virus inactivation and attachment, or the computational tool QMRAwell. QMRAwell is designed for unconfined and (semi)confined sandy aquifers with a forced groundwater gradient due to pumping. QMRAwell can also be used to conduct  QMRA.

How to cite: Schijven, J., van den Berg, H., and Rutjes, S.: Protection of groundwater against microbial contamination, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-11053, https://doi.org/10.5194/egusphere-egu23-11053, 2023.

EGU23-11264 | ECS | Posters on site | HS2.3.2

Occurrence and Distribution of PFAS in the River and Groundwater at Two Danube Sites 

Ali AA Obeid, Thomas James Oudega, Ottavia Zoboli, Claudia Gundacker, Alfred Paul Blaschke, Matthias Zessner, Ernis Saracevic, Nicolas Devau, Margaret E. Stevenson, Nikola Krlovic, Meiqi Liu, Zsuzsanna Nagy-Kovács, Balázs László, Gerhard Lindner, and Julia Derx

Per- and Polyfluoroalkyl Substances (PFAS) are chemicals used for many domestic and industrial purposes related to their physicochemical properties. However, those same properties make them mobile and persistent in the environment, and on top of that, they are toxic and can affect human health in the short and long term, as they are bio-accumulative. Many processes govern the transport of PFAS in the surface waters and groundwater, e.g., sorption, biodegradation, co-transport, and transformation. Monitoring PFAS at different locations can help understand these processes and provide datasets to calibrate and validate reactive transport models simulating PFAS fate and transport. This study compares PFAS presence and distribution in river water and groundwater at two Danube river sites. One site is characterized by a steady water level in the river and natural flow from the river to the groundwater, with a clogging layer at the aquifer-river interface. In contrast, the other site has a more dynamic water level in the river, several pumping wells affecting water infiltration rates, and lacks a clogging layer.

Samples were collected monthly for 12 months at the static study site and 8 months at the dynamic study site. Targeted analysis for 32 PFAS compounds has been carried out using liquid chromatography mass spectrometry (LCMS). The concentrations of the compounds were generally less than 20 ng/l, and most of the compounds were lower than the limit of quantification/detection. The results show that 3H-perfluoro-3-[(3-methoxypropoxy) propanic acid] (ADONA) had the highest concentration at the two sites, both in the river and groundwater. The longer chain PFAS exhibited a slight reduction in concentration from the river towards groundwater due to, most likely, sorption, while the shorter chain did not. The 6:2 FTS precursor was detected in the river but not in the groundwater. For some substances, the concentrations were higher in the groundwater compared to the river, indicating either background water influence, a transformation of PFAS, different transport routes (e.g., accumulation over time), or longer flow paths. Longer chain lengths, greater than 9 carbon atoms, were never detected above the limit of quantification in the river and groundwater. More PFAS compounds were detected at the dynamic study site than at the static one, even though, it is located further downstream, indicating nearby PFAS sources or/and influents along the river course. It is worth mentioning that large wastewater treatment plants are discharging their effluent downstream of the static site, in addition to sewer overflows from large cities in between. The PFAS concentrations in the river and groundwater during one high-flow event showed little difference compared to the ones during basic monthly monitoring at both study sites, however, another high flow event is needed to confirm this observation.

How to cite: Obeid, A. A., Oudega, T. J., Zoboli, O., Gundacker, C., Blaschke, A. P., Zessner, M., Saracevic, E., Devau, N., Stevenson, M. E., Krlovic, N., Liu, M., Nagy-Kovács, Z., László, B., Lindner, G., and Derx, J.: Occurrence and Distribution of PFAS in the River and Groundwater at Two Danube Sites, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-11264, https://doi.org/10.5194/egusphere-egu23-11264, 2023.

Karst aquifers are vulnerable to contaminations due to their specific characteristics which allow for a rapid recharge and high velocities within the saturated zone. Contaminants such as pathogenic bacteria, viruses, and antibiotic resistance genes (ARG) can enter the groundwater and reach springs at high concentrations (Auckenthaler et al., 2002). This poses a potential threat, especially considering that drinking water treatment is less effective against microbial contaminations (Auckenthaler & Huggenberger, 2003) or missing, particularly in developing countries. Potential input of such contaminants is related for example to spills and leaks of waste water or application of manure. Many small-scale laboratory studies have been performed to understand the mobility of virus and bacteria, yet only little is known from large scale field tracer tests.

We performed tracer tests using different non-pathogenic bacteria, bacteriophages, and extracellular DNA as surrogates for pathogens and ARGs together with uranine within the catchment of the Gallusquelle karstic spring. The average flow velocities in the groundwater system were about 30 and 87 m/h during our tracer tests. Tracers were injected as instantaneous input (10 minutes input time). Periodical sampling for the biological tracers started with the first detection of uranine about 80 to 90 hours after injection. Bacterial and eDNA tracers were analysed using qPCR methods while bacteriophages were additionally analysed using a culture-based method (plaque assay) to count active phages. First data indicates that all tracer materials were successfully injected into the groundwater and detected at the Gallusquelle spring. Results of the first tracer test suggest that all used tracer materials were transported over at least 3 km within the system. Furthermore, active bacteriophages of the second tracer test were transported over 9 km from a stormwater detention basin to the spring within 90 hours. 1D-transport modelling revealed much lower mass recovery for these active phages compared to the soluble tracer uranine (about 1% as maximum compared to approximately 31% for uranine).

 

Auckenthaler, A., Raso, G. & Huggenberger, P. (2002): Particle transport in a karst aquifer: natural and artificial tracer experiments with bacteria, bacteriophages and microspheres. Water Sci. Technol., 46, 131-138

Auckenthaler, A. & Huggenberger, P. (2003): Schlussfolgerungen und Empfehlungen. In: Auckenthaler, A. & Huggenberger, P. [eds.]: Pathogene Mikroorganismen im Grund- und Trinkwasser. Birkhäuser Verlag, Basel, 184 S.

How to cite: Serbe, R., Schiperski, F., Stelmaszyk, L., Stange, C., and Scheytt, T.: Transport of bacteria, bacteriophages, and extracellular DNA as surrogates for pathogens and antibiotic resistance genes in a karst aquifer (Gallusquelle, South-West Germany), EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-11903, https://doi.org/10.5194/egusphere-egu23-11903, 2023.

EGU23-12147 | Posters on site | HS2.3.2

Upscaling bacterial overland transport – a multi-parametric approach 

Julia Derx, Rita Linke, Regina Sommer, Peter Strauss, Alba Hykollari, Alexander Faltejsek, Jack Schijven, Alfred Paul Blaschke, Alexander Kirschner, and Andreas Farnleitner

Water contaminated with human and animal enteric pathogens puts public health at serious risk. All countries and regions of the world require highly robust and effective water management and treatment systems to guarantee safe water and protect public health. To this end, we need accurate predictions of the origin of pathogens , how they move through the environment and where they end up.

This study is part of a four-year project and aims to develop new bacterial overland transport - BOT models to provide answers to the above questions. The project takes a holistic, quantitative approach to transfer BOT model parameters onto large scales. Small-scale precipitation experiments are conducted in the laboratory and larger-scale experiments are conducted using a rainfall simulation under real environmental conditions. The state-of-the-art combination of quantitative, microbiological, and molecular methods and parameters will provide the scientific basis for more accurate predictions of BOT, which eventually may be extended to viruses and protozoa in the future.

How to cite: Derx, J., Linke, R., Sommer, R., Strauss, P., Hykollari, A., Faltejsek, A., Schijven, J., Blaschke, A. P., Kirschner, A., and Farnleitner, A.: Upscaling bacterial overland transport – a multi-parametric approach, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-12147, https://doi.org/10.5194/egusphere-egu23-12147, 2023.

EGU23-13821 | Orals | HS2.3.2

Nitrification and urease inhibitors - From fields to drinking water resources? 

Ursula Karges, Christine Kübeck, Tim aus der Beek, Sebastian Sturm, Richard Beisecker, Theresa Seith, Muhammad Zeeshan, and Sondra Klitzke

Applications of nitrification and urease inhibitors (NUI) with nitrogen fertilisers on agricultural soils are intended to improve the efficiency of nitrogen fertilisers and also to prevent nitrogen emissions from the fertilisers. However, the deliberate release of chemicals into the environment carries a certain degree of risk due to spreading in the water systems. Both sensitive ecosystems and water supplies may be affected. Processes that need to be considered for a reliable assessment regarding the fate and distribution of these substances in the different compartments are manifold. So far, reliable predictions in literature are scarce and regulatory approaches are based on limited information on substance fate.

Yet, two out of the ten NUIs currently approved in Germany, have been found in surface waters, prompting further investigation. In this context, no analytical method has been established so far for some of the other NUIs, thus there is no information available on the occurrence of these substances. In order to gain transparency on the actual environmental fate and implications for drinking water production of these NUI has been analyzed In addition to legal approval procedure different processes and scenarios relevant to their fate were investigated in the INHIBIT project.

Following a comprehensive literature review, experimental investigations were carried out to further evaluate the environmental behaviour of these substances on an empirical basis. Initially, a multi-method was developed for the simultaneous determination of 1H-1,2,4-triazole (triazole), dicyandiamide (DCD), 3,4-Dimethylpyrazol-phosphate (DMPP), 3-Methylpyrazole (3-MP), N-(n-butyl)thiophosphoric triamide (NBPT) and N-(2-nitrophenyl)phosphoric triamide (2-NPT) in soil pore water. Experiments conducted in this research project provided essential empirical information on the hydrolysis stability, degradation behaviour and sorption tendency in soils for selected NUI. In addition, vessel, column, lysimeter and practical field application tests were carried out to obtain empirical information on the leaching risk of these substances via the transport pathway unsaturated zone-leachate-groundwater. Furthermore, the indirect input pathway via infiltrating surface waters (bank filtration) was investigated. Studies were carried out on different soils and using different parameters in order to depict different site conditions.

Results indicated a high hydrolysis stability for the nitrification inhibitors (NI) DCD, DMPP, 3-MP and triazole. The hydrolysis stability of the urease inhibitors (UIs) NBPT and 2-NPT is strongly pH-dependent. While NBPT is particularly unstable in an acidic environment, 2-NPT shows the lowest stability in a more alkaline environment. Sorption tendency to soils of all compounds was low. Microbial degradation of NI in soils was lower compared to urease inhibitors (UIs). Overall, the NI triazole, DCD, 3-MP and DMPP were found to be potentially relevant substances for drinking water production. The NI active substances DCD and triazole were additionally monitored in several surface waters and were frequently detected, in some cases at very high concentrations of several µg/L. These findings underline the relevance of these substances for water resources.

How to cite: Karges, U., Kübeck, C., aus der Beek, T., Sturm, S., Beisecker, R., Seith, T., Zeeshan, M., and Klitzke, S.: Nitrification and urease inhibitors - From fields to drinking water resources?, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-13821, https://doi.org/10.5194/egusphere-egu23-13821, 2023.

EGU23-14533 | Orals | HS2.3.2

Fate and transport modelling of microbial water quality: impacts of climate change and socioeconomic development 

Ekaterina Sokolova, Viktor Begion, M. M. Majedul Islam, and Mia Bondelind

Anthropogenic activities in a watershed may pose human health risks due to faecal contamination of surface waters. Thus, socioeconomic development is important when predicting future microbial water quality. Moreover, climate change alters meteorological conditions, thereby affecting flow regimes as well as fate and transport of microorganisms. In this study, possible risks due to socioeconomic development and climate change were assessed for the drinking water source Lake Vomb in Sweden by means of water quality modelling. The hydrological model ArcSWAT and the hydrodynamic model MIKE 3 FM were used to simulate fate and transport of two microorganisms, i.e., Cryptosporidium and E. coli, from the watershed to the water intake. The hydrological model and the hydrodynamic model were calibrated and validated using observed data on water flow and water temperature, respectively. The water quality in the watershed and in the lake was simulated for a baseline scenario and for future scenarios in the second half of this century. The future scenarios were formulated based on Representative Concentration Pathways (RCPs) and Shared Socioeconomic Pathways (SSPs). The modelling results illustrated the effects of climate changes and of socioeconomic development. The results were also interpreted in the context of infection risks to drinking water consumers using quantitative microbial risk assessment. This study clearly illustrates that socioeconomic development is important to include when investigating future microbial water quality.

How to cite: Sokolova, E., Begion, V., Islam, M. M. M., and Bondelind, M.: Fate and transport modelling of microbial water quality: impacts of climate change and socioeconomic development, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-14533, https://doi.org/10.5194/egusphere-egu23-14533, 2023.

EGU23-15047 | Orals | HS2.3.2

Transfer patterns of pharmaceuticals used in agriculture into streams under Mediterranean climate at the catchment-scale 

Nico Hachgenei, Guillaume Nord, Lorenzo Spadini, Nicolas Robinet, Christine Baduel, and Céline Duwig

Livestock-breeding relies on a large array of pharmaceuticals. Many of them may pose a risk to aquatic life if they reach surface water bodies.  Depending on their physicochemical properties, some pharmaceuticals present strong sorption coefficients and are thus not expected to reach surface water bodies under most conditions. Mediterranean climate is characterized by a dry summer followed by intense storm events. We studied the effect of this climatic condition on the risk of transfer of pharmaceutical residues to streams at the catchment-scale. The study area is the 42km2 Claduègne catchment in the French Ardèche department. It is characterized by extensive agricultural land-use under Mediterranean climate.

Surveys with local livestock farmers were conducted in order to identify the commercial pharmaceutical products and the active ingredients systematically used in the study area as well as their application rate, frequencies and seasonal patterns. Stream water was analyzed on high frequency (up to 3h-1) during flood events and compared to some samples outside of flood events. A total of 32 liquid water samples were collected and analyzed for 3 veterinary pharmaceuticals systematically used in the study area as well as 14 molecules of various use. They were concentrated via solid phase extraction and analyzed using high performance liquid chromatography (HPLC) coupled to a tandem mass spectrometer. The concentration values where below the limits of detection (0.1 - 1 ng L-1) most of the time, but peaked at high concentrations for short periods during flood events. The concentration reached up to 355 times the Predicted No Effect Concentration (PNEC) for Fenbendazole FBZ, the antiparasitic used in pork in the region. This indicates that rapid transfer processes during flood events represent an elevated risk of transfer of these molecules toward streams. Parallel transit time modelling revealed high event water fractions during flood events in the studied catchment.

We conclude that under these climatic conditions, special care should be taken after treatment application to avoid pastures that are hydrologically connected to surface water bodies. In addition, the results suggest that low-frequency monitoring is not sufficient to detect these high concentration levels that exist during very short durations of a few hours or less.

How to cite: Hachgenei, N., Nord, G., Spadini, L., Robinet, N., Baduel, C., and Duwig, C.: Transfer patterns of pharmaceuticals used in agriculture into streams under Mediterranean climate at the catchment-scale, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-15047, https://doi.org/10.5194/egusphere-egu23-15047, 2023.

EGU23-16837 | ECS | Orals | HS2.3.2

Modelling multitudes of pharmaceuticals in the global river system at high spatial resolution 

Heloisa Ehalt Macedo, Bernhard Lehner, Jim Nicell, Usman Khan, Eili Klein, and Günther Grill

Treated and untreated domestic wastewaters that are discharged into surface waters often contain a variety of chemical substances, including residuals of pharmaceuticals that are not fully metabolized by the human body. These substances may be harmful to the health of aquatic ecosystems and to humans who rely on them as a source of water supply. Despite growing concerns and their frequent detection in wastewaters and surface waters, the concentrations of pharmaceuticals are not regularly monitored in water bodies. As an alternative to comprehensive monitoring campaigns that tend to be very resource intensive, contaminant fate models may be used to provide information to support the development of targeted local monitoring schemes in regions of highest exposure to pharmaceuticals in the environment as well as the prioritization of substances for further investigation.

In this work, a global contaminant fate model (called HydroFATE) was developed with the objective of estimating the concentration of contaminants of emerging concern (including pharmaceuticals) in the global river network at a high spatial resolution (500 m). The contaminant emission is calculated based on consumption per capita and population density. Then, the contaminant loads of treated or untreated wastewaters are reduced in the model either by centralized or decentralized wastewater treatment, by natural attenuation in soils and runoff, and/or by decay processes in rivers and lakes. HydroFATE’s structure is based on a vector routing structure, which besides its spatial precision being higher than in global pixel-based models, it is also fast to process. This key aspect allows for more complex analyses, including repeated execution of multiple substances and different scenarios in a short period of time, making HydroFATE a capable tool to inform on the prioritization of substances.

The model’s performance was validated by comparing predicted concentrations in river reaches worldwide against literature reports of measured concentrations of 22 broadly consumed antibiotics for which at least sparsely monitored data existed. The sensitivity of the model’s predictions was tested by altering key model parameters. This validation process showed that HydroFATE is generally able to predict aquatic concentrations measured worldwide to within one order of magnitude, which is judged to be sufficient for the intended purposes of the model.

Finally, HydroFATE was applied to estimate the concentrations of the 40 most widely used antibiotics in households worldwide and to compare these concentrations, both individually and cumulatively, to established no-effect thresholds of environmental exposure. It was estimated that a total of 8,500 tonnes of antibiotics per year are discharged into the river system. We found that 6.0 million km of rivers worldwide may have environmental exposure levels that exceed the no-effect concentration of antibiotic pollution during low streamflow conditions, with the largest extent of these rivers being in Southeast Asia, the most densely populated region in the world. The main contributors of exposure were found to be the widely and heavily used antibiotics amoxicillin, ceftriaxone, and cefixime.

How to cite: Ehalt Macedo, H., Lehner, B., Nicell, J., Khan, U., Klein, E., and Grill, G.: Modelling multitudes of pharmaceuticals in the global river system at high spatial resolution, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-16837, https://doi.org/10.5194/egusphere-egu23-16837, 2023.

EGU23-17381 | ECS | Orals | HS2.3.2

Understanding the connectivity of pharmaceutical pollution in river catchments 

Julia Costescu, Louise Bracken, Laura Turnbull-Lloyd, Sim Reaney, and Damian Crilly

The near ubiquitous presence of pharmaceutical compounds in environmental waters represents an emerging cause for concern, but gaps remain in our understanding of how human and veterinary pharmaceuticals enter and travel through river catchments. A more holistic approach is needed in order to develop effective management strategies that conform to the catchment-based approach, although this is complicated by the patchy nature of available monitoring data for river water and by the significant seasonal variation in concentrations which makes comparisons even within datasets tenuous. Here, an exploration of pharmaceutical concentrations across the Aire catchment in the UK aims to provide insight into how the underlying connectivity of the catchment system, conceptualized as a source-pathway-receptor model, may determine observed patterns of contamination. To account for temporal variations of inputs and flow, samples collected on two separate occasions (corresponding to low and high flow conditions, respectively) were used to create two spatial snapshots for contamination with nine representative compounds. The snapshots were then used to explore spatial patterns in the catchment and what factors – topographic, physico-chemical, or related to potential sources and pathways for pharmaceutical pollution – may influence them. For the first snapshot, conducted in low flow conditions, none of the locations had concentrations above the limit of detection for five of the nine target analytes (Atenolol, Diclofenac, Erythomycin, Iopromide and Sulphadiazine). Results for the detected compounds have emphasized the difference in spatial patterns based on use category: as opposed to the veterinary use compound (Cypermethrin), the human use compounds (Carbamazepine, Lidocaine and Sucralose) showed significant correlation to contributing area, as well as to population served by the wastewater treatment plants upstream of the sampling sites and corresponding estimates for amounts of prescribed active ingredient. Sucralose also produced strong correlations to Carbamazepine and Lidocaine, supporting its use as a proxy for contamination with human pharmaceuticals, alongside the more frequently cited Carbamazepine. Ultimately, this research will inform the development of a graph representation of the system, used to assess the relative contribution of different pathways as they connect to the river channel and to inform as to the best intervention points within the catchment.

How to cite: Costescu, J., Bracken, L., Turnbull-Lloyd, L., Reaney, S., and Crilly, D.: Understanding the connectivity of pharmaceutical pollution in river catchments, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-17381, https://doi.org/10.5194/egusphere-egu23-17381, 2023.

Heavy metal pollution in the riverine system is a major concern as it is a primary source of fresh water and has the potential to cause minuet to severe health impacts in humans. Excess heavy metal contamination in the riverine system may introduce potentially toxic elements into the aquifers via recharge or vice versa. The present study is aimed to understand the heavy metal pollution and the human health risk assessment of surface and groundwater in the Upper Yamuna River Basin (UYRB) and its spatial distribution.  For the study, twenty-eight river water and forty-eight groundwater samples were collected in May 2022 and analyzed for 15 heavy metals. Except for a few metals in groundwater (As, Fe, Mn, and Al) and surface water (As, Al, Mn), the rest were in compliance with the BIS and WHO acceptable limits. The mean metal concentration in groundwater were observed in the order of Cd < Cu < Cr < Ni < Co < Mo < Li < As < Al < Ba < B < Mn < Sr < Zn < Fe, whereas in surface water it followed the order of Cd < Cu < Cr < Ni < Co < Mo < Zn < Li < As < Ba < Al < Mn < Fe < B < Sr. The non-carcinogenic (HI) value for groundwater in adults ranged between 0.3 – 15.4 with an average of 3.95, while it ranged between 0.3 – 7.4 with an average of 2.4 for river water.  Similarly, the average incremental lifetime cancer risk (ILCR) value for adults in groundwater is 1.4 × 10-3 and 9 × 10-4 for river water. The health risk implication in children were found to be higher than the adults. The higher HI and ILCR values may be associated with the high arsenic concentration compared to their standard acceptable limit. Even though the HI and ILCR values exceeded the standard values, the heavy metal pollution (HPI) index values for all the samples were below the permissible limit. It may be due to the lower concentration or the absence of major concerned metals (Cd, Cu, Cr, Ni, etc.). Heavy metals are varyingly distributed in the basin, whereas, the lower catchment, which is the major urban center of the country is found to have comparatively higher concentrations of heavy metals and related health risks.

Keywords: Heavy metal, Yamuna river, Human health assessment, Pollution index

How to cite: Rajan, S. and Raju, N. J.: Heavy metal contamination in surface and groundwater and its human health risk assessment in the Upper Yamuna River Basin, India, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-704, https://doi.org/10.5194/egusphere-egu23-704, 2023.

EGU23-906 | ECS | Posters virtual | HS2.3.3

Land Use Practices and their Resulting Impacts on Surface Water Quality 

Emily Nottingham and Tiffany Messer

Contaminants of emerging concern (CECs) are becoming a major source of water impairment throughout the world. Land use practices within urban and rural areas have shown to be sources of CECs. Contaminants enter the environment through direct application or waste disposal with runoff and soil leaching depositing CECs into streams and lakes. Therefore, this study sought to characterize the nutrients, heavy metals, pesticides, human pharmaceuticals, and personal care products appearing in streams across varying Kentucky landscapes. Field sampling included using both Polar Organic Chemical Integrative Samplers and water grab samples from March-October 2022 at four stream sites in an oil and gas, urban, mining, and agricultural regions of the Commonwealth. Preliminary results exhibited occurrence of contaminants varied by location, season, and flood conditions. The urban site resulted in the highest concentrations of chloride, nitrate-N, caffeine, and cotinine (by-product of Nicotine), particularly in the spring months. The watershed with the most active mines showed the highest concentrations of strontium along with significantly larger concentrations of sulfate that were above the ecotoxicology limits (200 mg/L) and EPA secondary drinking water standards (250 mg/L). The watershed associated with the most oil and gas wells showed the highest concentrations of barium. This site also showed higher concentrations of human pharmaceuticals (e.g., Carbamazepine, Codeine, Diltiazem, Diphenhydramine, Fluoxetine), likely a result of an older wastewater infrastructure and straight-pipes that discharged untreated water into the sampled stream. Finally, the agricultural site showed the highest concentrations of aluminum, iron, and lead and had higher sediment loads during flood events in the spring months, which likely resulted in the concentrations of these three metals being above the chronic criteria for aquatic organisms. Additionally, the agricultural site had the highest concentrations of both lincomycin and sulfonamide, common antibiotics used to treat livestock. This study is the necessary first step in reaching the UN’s Sustainable Development Goals by developing a comprehensive understanding of land use impacts on contaminant presence and concentration in surface waters. Further, findings from this project will be incorporated into the design and placement of best management practices to limit the impact of CECs.

How to cite: Nottingham, E. and Messer, T.: Land Use Practices and their Resulting Impacts on Surface Water Quality, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-906, https://doi.org/10.5194/egusphere-egu23-906, 2023.

EGU23-2267 | ECS | Orals | HS2.3.3 | Highlight

Comparative assessment of PFAS concentrations in emission pathways, surface and groundwater in the upper Danube Basin 

Meiqi Liu, Ernis Saracevic, Nikola Krlovic, Ottavia Zoboli, Steffen Kittlaus, Gerhard Rab, Ali Obeid, Thomas Oudega, Julia Derx, and Matthias Zessner

Recent years have seen increasing interest in Per- and Polyfluoroalkyl Substances (PFAS) in the urban water cycle. PFAS are human-manufactured chemicals that have been employed globally in industrial and household products with outstanding chemical stability and mobility. This study set out a one-year monitoring scheme as a basis to better understand the sources, transport and fate of PFAS at a large catchment scale. The monitoring results will further assist the development of a contamination distribution model.

Nine Danube tributary sites including regions with low and high pollution risk were selected, based on the existing monitoring results from other research and inventories of hotspots like industries and landfills, to investigate the appearance of pollutants along the surface water of the catchment. Two locations on the Danube mainstream were targeted for more frequent monitoring of surface water and connected groundwater, furthermore, bank-filtration models will be built for these sites. In the case of point sources, five municipal wastewater treatment plants, four direct industrial dischargers and four legacy landfill sites were selected to identify the impact of these hotspots. Surface runoff at three small catchments dominated by either arable land, grassland or forests, together with samples of atmospheric deposition at three city sites were collected to cover potential diffuse pathways of PFAS transport in the catchment.

At the current stage, two-thirds of the sampling has been carried out for the Danube locations and the rest of the sites are approaching completion. Targeted analysis method using liquid chromatography mass spectrometry (LCMS) was employed, to assess the presence of thirty-two different PFAS compounds.

Despite the fact of being restricted in the EU, PFOA and PFOS were still detected in most samples. Additionally, short-chain perfluoroalkyl carboxylic (PFCA) and sulfonic (PFSA) acids were prominently detected in 110 surface and groundwater samples, while 97% of the total concentration exceeds the newly proposed EQSD(Environmental Quality Standards Directive) of 4.4 ng/L to EU in 2022. What stands out in the results is that, at a site downstream of an industrial hotspot region in the upper part of the catchment, samples show a total PFAS concentration greater than 2700 ng/L, a significant proportion of which came from two replacement compounds, ADONA and GenX. This “signal” is still observed far downstream. In contrast to most of the tributaries, ADONA and GenX were detected in all samples from the two Danube sites and accounted for the largest proportion of the total concentration. Analysis of twelve groundwater samples below one landfill site observed a median total concentration of 110 ng/L, meanwhile three landfill leachate samples were analysed showing amounts greater than 720 ng/L. In addition to the compounds mentioned above, the presence of 6:2 fluorotelomer sulfonate (FTS), Perfluorooctanesulfonamide (FOSA) and sulfonamidoacetic acid (FOSAA) were not negligible in these samples. Wastewater samples are still under evaluation and details will be shown at the conference.

The monitoring results indicate the significant contribution of hotspot regions and point sources to the PFAS contamination in the river, but at the same time, diffuse inputs must not be ignored.

How to cite: Liu, M., Saracevic, E., Krlovic, N., Zoboli, O., Kittlaus, S., Rab, G., Obeid, A., Oudega, T., Derx, J., and Zessner, M.: Comparative assessment of PFAS concentrations in emission pathways, surface and groundwater in the upper Danube Basin, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-2267, https://doi.org/10.5194/egusphere-egu23-2267, 2023.

EGU23-2642 | ECS | Orals | HS2.3.3

Chemical characterization of urban waters aimed for managed aquifer recharge in the Hesbaye chalk aquifer (Liège, Belgium) 

Robin Glaude, Nataline Simon, Philippe Orban, and Serge Brouyère

Managed Aquifer Recharge (MAR) is a viable method that has gained recognition for storing alternative waters in aquifers for subsequent recovery or environmental benefits. It has the potential to increase the supply of fresh water and protect aquifers from overexploitation and degradation, but it might also carry the risk of contaminating groundwater since the recharge water used may contain a wide range of organic and inorganic contaminants. Therefore, it is important to carefully assess the quality of these alternative sources of water (such as runoff water) used for MAR and implement appropriate treatment measures to remove or neutralize any contaminants that may be present. The purpose of this research is to conduct a preliminary feasibility study of MAR as a potential mitigation measure in the Hesbaye chalk aquifer since this major source of drinking water for the region of Liège (Belgium) is threatened both in terms of quantity and quality. In the first phase of the study, the quality of runoff waters collected from stormwater basins along national roads and in a national airport area was analysed and certain contaminants of emerging concerns were detected at concentrations close to drinking water limits or environmental safety guidelines. In particular, contaminations with PFAS compounds have been detected in stormwater basins in the airport area with maximum values reaching up 490, 330 and 250 ng/L for PFECHS, PFPeA and 6:2 FTS respectively. Other contaminants of emerging concerns such as alkylphenols and organophosphate flame retardants have been detected as well. In a second phase, estimates of expected recharge rates were determined through in-situ experimentation using a small infiltration pond with a pressure sensor and innovative active-DTS measurements with buried optical fiber cables to monitor the infiltration of water into the loess (eolian loam) sediments overlaying the Hesbaye chalk aquifer. Finally, these input data have been used to perform 1D transport modelling simulations in order to make a preliminary evaluation of the risk of groundwater deterioration in the case where these raw runoff waters are infiltrated without pre-treatment. Column infiltration tests are planned to get a better estimation of the soil attenuation capacity in the unsaturated zone. This study is unique in that i) it explores the feasibility of MAR in a country in which the method is not well-developed yet, ii) the use of airport runoff water as a potential source of recharge water is novel and has not been widely examined in previous MAR studies and iii) aquifer-soil treatment in loess sediments overlaying a chalky fractured aquifer is a unique hydrogeological setting to perform MAR operations.

How to cite: Glaude, R., Simon, N., Orban, P., and Brouyère, S.: Chemical characterization of urban waters aimed for managed aquifer recharge in the Hesbaye chalk aquifer (Liège, Belgium), EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-2642, https://doi.org/10.5194/egusphere-egu23-2642, 2023.

Oxytetracycline (OTC) is frequently detected antibiotic in surface water because it is widely used for both humans and animals; however, it is difficult to be completely removed by conventional wastewater treatment due to its recalcitrant nature. By using photo-Fenton-like process, OTC could be degraded or transformed, while only a few studies were conducted to detect its transformation products (TPs). In this study, a UHPLC (Ultra-high-performance liquid chromatography) system coupled with a Triple TOF 5600+ mass spectrometer (AB SCIEX Co., Redwood City, CA, USA) was used to identify the TPs of OTC during the heterogeneous photo-Fenton process. The heterogeneous photo-Fenton-like process was performed with MIL-100(Fe) and 50 mg/L of H2O2 under visible light, then 12 kinds of TPs were observed. The peak area of OTC (m/z 461) decreased immediately as the reaction wend, and 8 kinds of TPs were observed only after 1 min-reaction. OTC transformed initially and mainly by decarbonylation of C1 (m/z 433), hydroxylation of the aromatic ring (m/z 477a) and C11a (m/z 477b), and demethylation at low N-C bonds (m/z 447). m/z 477a and 475 were predominantly observed because the aromatic ring is one of the most favorable target site to be oxidized by ·OH. Additionally, keto/enol at C11a-C12 is another favorable oxidation site forming m/z 477b; further hydroxylation generated m/z 493, and additional secondary alcohol oxidation led to the formation of m/z 491. A methyl group at C4 abstraction (m/z 447) was degraded further into m/z 429 by dehydration of C6-C5a, abstraction of hydrogen at C5 turned into m/z 459, and m/z 441 was formed by dehydration at C6.

How to cite: Park, J.-A.: Transformation products of oxytetracycline by heterogeneous photo-Fenton-like process, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-3028, https://doi.org/10.5194/egusphere-egu23-3028, 2023.

Modelling environmental concentrations of pesticides at landscape-level is of growing interest for pesticide registration and product stewardship, including higher-tier studies in risk assessment, mitigation measures, monitoring support and decision making. Typically, processes such as runoff, drainage, and leaching are well represented in existing modelling concepts at point and landscape scale. However, the modelling of off-target spray drift is often neglected or simplified at the landscape-level scale due to its high computational costs. Attempts at implementing spray drift into landscape-level modelling often rely on an external calculation of drift curves with pesticide masses added directly to the channel network. Although this approach enables the estimation of drift entries based on the proximity of source areas to water bodies, it may be insufficient in representing the spatial distribution of spray drift depositions in the landscape.

Our modelling approach aims to enable computationally efficient landscape-level spray drift predictions, which account for short term and local weather conditions. Therefore, a spray drift model for ground application was developed, by combining a mechanistic droplet model with a 3D Gaussian puff model. The mechanistic droplet model predicts the trajectory and mass balance of individual representative droplets, based on environmental conditions and application operations. This trajectory is then combined with a 3D Gaussian puff model to predict pesticide concentrations in the landscape, which are used to predict pesticide deposition rates. The model considers important spray drift predictors such as weather conditions, drop size distribution, physio‑chemical properties of the active ingredient, and operational conditions. The model showed realistic and expected behavior for variations in important input parameters (e.g., different nozzle types, wind speed). Furthermore, validation against two spray drift field studies showed good agreement between simulated and observed values.

To increase the understanding of pesticide transport pathways at the landscape-level, it is planned to combine the spray drift model in a modular fashion with a high-resolution SWAT+ (Soil and Water Assessment Tool) model of an agriculturally dominated catchment in Germany. Moreover, the spray drift model is expected to be a useful tool in the elucidation of monitoring data and the assessment of ecotoxicological risks for non-target organisms.

How to cite: Fuchs, M., Gebler, S., and Lorke, A.: Estimating high resolution exposure at landscape-level – on the development of a 3‑dimensional Gaussian puff droplet drift model, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-5361, https://doi.org/10.5194/egusphere-egu23-5361, 2023.

Water and sediment transport minerals, micro-plastics, heavy-metals, pathogens, DNA, RNA, and emerging contaminants through river networks. We would like to use point observations of these concentrations to determine where and how much of these are entering the network. However, downstream samples are mixtures of all the potential upstream sources. Separating out the contribution of an individual source requires "unmixing" the network's waters or sediments.

Here, we describe a very efficient approach to perform such an unmixing, identifying the contribution from each nested sub-catchment in a drainage basin. First, we abstract the sub-catchments defined by our sampling sites into a directed acyclic graph. Each node (sub-catchment) in the graph is defined as having an upstream area, which we know, and a tracer source concentration, whose value we want to find. If we assume that when two rivers meet their tracers' fluxes are combined conservatively then downstream concentrations are the mixture of all upstream concentrations, weighted by upstream area.

To solve for the source concentration of each sub-catchment we define a convex optimisation problem, minimising the relative difference in the predicted and observed tracer concentration at each sample site. Due to its convexity, this optimisation problem can be solved in less than a second for networks of a 100 nodes. Uncertainties can be estimated using a Monte-Carlo style approach. We have made an open-source, Python implementation of this algorithm available on GitHub. This implementation requires as input (1) a spreadsheet containing sample site locations and observed tracer concentrations and (2) a D8 flow-direction raster map. This is a powerful approach for locating and quantifying the sources of conservatively mixed tracers or pollutants in drainage networks.

How to cite: Lipp, A. and Barnes, R.: Identifying tracer and pollutant sources in drainage networks from point observations using an efficient convex unmixing scheme, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-5368, https://doi.org/10.5194/egusphere-egu23-5368, 2023.

Atrazine is one of the most frequently found pesticides in groundwater and surface water. Under natural light, the half-life of this herbicide in aqueous medium is around 250 days. Atrazine has shown the potential to alter food webs, decrease diversity, and can interfere with species composition. In the current study, electrocoagulation powered by solar energy was used to eliminate atrazine from the aqueous solution. Aluminum and copper electrodes were used to investigate the effect of different operating parameters such as contact time (10-60 min), applied voltage (5-25 V), initial pH (3-11) of the feed water, types and concentration of supporting electrolyte like NaCl, Na2SO4 (100-500 mg/L) on the removal of atrazine. The loss of electrode mass and sludge generation were also evaluated. The effect of the initial concentration of atrazine was observed in the range of 3-15 mg/L. The pH of feed water solutions in all the experiments increased, indicating the necessity for neutralization after electrocoagulation.

The possible mechanisms of atrazine removal were explored using several techniques such as X-ray Diffraction (XRD), Fourier Transform Infra-Red (FTIR) spectroscopic analysis. The particle size, surface structure, and shape of dried sludge particles were analyzed using a scanning electron microscope. The energy consumption and operating cost calculations of the electrocoagulation process infer that this technique is not energy-demanding. Kinetic analysis demonstrated that atrazine removal followed first-order rate kinetics. Removal of atrazine from real river water matrices was also assessed in the current research. Current work indicated that solar-powered electrocoagulation is a promising approach for the elimination of atrazine in the treatment of water and wastewater in decentralized mode. 

How to cite: Biswas, B. and Goel, S.: Atrazine removal from river water using direct current and solar-powered electrocoagulation, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-6156, https://doi.org/10.5194/egusphere-egu23-6156, 2023.

EGU23-6590 | ECS | Posters on site | HS2.3.3

Multi-element compound-specific isotope analysis of chlordecone during abiotic transformation reactions 

Maria Prieto-Espinoza, Laure Malleret, and Patrick Höhener

Chlordecone (CLD; C10Cl10O) is an organochlorine pesticide extensively used between 1960s and 1990s in the French West Indies (FWI). Its massive use led to soil and river pollution which prompted its ban in 1993. CLD has a bis-homocubane structure and various chlorine atoms making it highly recalcitrant in the environment. To date, several environmental compartments of the FWI continue facing the legacy of CLD pollution. This study aims at improving the monitoring of the degradation (or recalcitrance) extent of CLD in the soils of the FWI following in situ chemical reduction (ISCR). Multi-element compound-specific isotope analysis (ME-CSIA) was used to identify changes of stable isotopes of CLD (i.e., 13C/12C and 37Cl/35Cl) produced during distinct abiotic reductive transformation reactions. Reductive transformation of CLD was tested in abiotic microcosms in the presence of either zero-valent iron, ascorbic acid, vitamin B12, or persulfate activated by microwave irradiation. CLD transformation was evidenced by the detection of several hydrochlordecones (after losses of one or two chlorine atoms) under all conditions. Enrichment of the 13C isotopes of CLD relative to 12C revealed distinct signatures during transformation reactions of CLD to maximum Δδ13C of +7.2 ‰. A novel stable Cl isotope analysis was performed by liquid chromatography quadrupole time-of-flight mass spectrometry (LC-QToF-MS). Ongoing Cl isotope analysis may establish a multi-element assessment in which abiotic CLD degradation pathways may be distinguished based on stable C-Cl signatures. Altogether, our results may provide an improved strategy to elucidate CLD degradation in contaminated soils of the FWI.

How to cite: Prieto-Espinoza, M., Malleret, L., and Höhener, P.: Multi-element compound-specific isotope analysis of chlordecone during abiotic transformation reactions, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-6590, https://doi.org/10.5194/egusphere-egu23-6590, 2023.

EGU23-6720 | ECS | Posters on site | HS2.3.3

Trends in pit-latrine usage in Malawi and their unintended impacts on groundwater quality 

Rebekah Hinton, Limbikani Banda, Christopher Macleod, Mads Troldborg, and Robert Kalin

Providing adequate and equitable sanitation to all by 2030 is central to achieving Sustainable Development Goal 6 (SDG6). Pit-latrines provide a low-cost, accessible form of sanitation, there has, therefore, been a significant increase in the rapidly growing Malawian population using pit latrines, largely driven by a reduction in open defecation. Whilst open defecation reduction is critical in managing waterborne pathogens and other contaminants, pit latrines can also result in both microbial and nutrient contamination of groundwater; faecal contamination of groundwater, resulting in contaminated boreholes, has already been documented in Malawi.

To forecast the level of pit-latrine usage in Malawi, we evaluate the trends in Malawian sanitary provision using linear modelling to estimate that currently 500,000 people gain access to sanitation in Malawi every year, requiring approximately 93,000 new pit-latrines to be constructed annually to accommodate this shift. The associated increase in pit-latrine density creates a heightened threat of borehole contamination and a key public health concern.

We also examine the nature of pit-latrine management and usage, presenting the results of a national survey of over 200,000 sanitary facilities. Whilst pit-latrines are usually associated with faecal contaminants, we found that 82.3% of pit-latrines had materials other than faecal waste deposited including rubbish, plastics, and oils; these present a danger of micropollutant contamination. Furthermore, we find that sustainable practises to manage waste deposited in pit-latrines, such as pit-latrine emptying, have low adoption.

Pit-latrine usage is already causing groundwater contamination in Malawi, this will only be exacerbated by our projected increase in pit-latrine usage as Malawi manages a growing population and actively pushes to eliminate open defecation.

This research is thanks to research and collaboration with the Government of Malawi with funding by the Scottish Government under the Scottish Government. Climate Justice Fund Water Futures Programme.

How to cite: Hinton, R., Banda, L., Macleod, C., Troldborg, M., and Kalin, R.: Trends in pit-latrine usage in Malawi and their unintended impacts on groundwater quality, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-6720, https://doi.org/10.5194/egusphere-egu23-6720, 2023.

EGU23-7315 | ECS | Orals | HS2.3.3

Predicting multi-species disinfection byproduct formation at small catchment scale using fluorescence spectroscopy data analyzed by machine learning 

Boris Droz, Elena Fernandez-Pascual, Goslan Emma, Jean O'Dwyer, Simon Harrison, Connie O'Driscoll, and John Weatherill

In Ireland, 82% of public water supplies originate from surface water sources which often contain elevated concentrations of dissolved organic matter (DOM) from a range of allochthonous (e.g., leaf leachate, manure) and autochthonous (e.g., macrophytes, biofilms, algae) catchment sources. During disinfection, this DOM may react with chlorine to produce potentially carcinogenic disinfection byproducts (DBPs) such as trihalomethanes (THMs), haloacetic acids (HAAs) and a range of nitrogen-containing species such as haloacetonitriles (HANs) and halonitromethanes (HNMs). As a result, Ireland has the highest reported number of total THM exceedances, (e.g., concentrations in excess of 100 μg L-1) in potable water across European Union member states. Removal of DOM precursors from raw water prior to chlorination has shown to be effective in mitigating DBP formation. However, significant infrastructural challenges remain in Ireland with many small treatment plants requiring costly upgrades. Hence, there is an urgent need for low-cost proactive monitoring tools to quantify DOM composition and concentration of source water to aid in the production of safe drinking water.

The overall aim of the present study is to better understand the spatiotemporal dynamics of DOM precursors and associated DBP formation at the scale of small river catchments (e.g., <50 km2) typical of drinking water source areas. To achieve this, we investigated two sub-catchments (34 km2 and 18 km2) of the River Lee basin, Republic of Ireland, which serve water treatment plants known to be at risk of THM exceedances. High resolution field sampling and measurement of DBP precursors (DOC, DIC, DON, NH4+, Cl and Br) and DOM optical properties using UV-vis and fluorescence excitation−emission matrix (EEM) spectroscopy were combined with 214 three-day batch chlorination experiments from 36 monitoring points (including 12 groundwater) from February to November 2021. A machine learning ensemble including bagging tree, generalized boosted regression and neural networks models was developed to explore and predict DBP formation potential using EEM parameters, including parallel factor analysis (PARAFAC) components and the measured DBP concentrations from the batch chlorination experiments. Therefore, we could predict with on average of 13% and 6% precision and error, respectively, the concentration of twenty DBPs produced from chlorination including four THMs, nine HAAs, four HANs, one HNM and two haloketone species. In addition, DOM molecular size distribution was measured on 25 samples by size exclusion – organic carbon – nitrogen detection (LC-OCD-OND) to explore the composition of DOM sources. Our findings highlight potential opportunities for DBP risk reduction through proactive online monitoring of source water using fluorescence EEM spectroscopy. This knowledge will help to organize appropriate mitigation strategies at the catchment level as well as aid in treatment process optimization using fluorescence EEM spectroscopy which surpasses the capabilities of traditional online UV-vis spectroscopy. Overall, the findings of our research will help to decrease the number of total THM exceedances in Ireland and better protect consumer health in relation to drinking water chemical quality around the world.

How to cite: Droz, B., Fernandez-Pascual, E., Emma, G., O'Dwyer, J., Harrison, S., O'Driscoll, C., and Weatherill, J.: Predicting multi-species disinfection byproduct formation at small catchment scale using fluorescence spectroscopy data analyzed by machine learning, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-7315, https://doi.org/10.5194/egusphere-egu23-7315, 2023.

EGU23-7659 | ECS | Posters on site | HS2.3.3

Agropollutants fate in the fields scale 

Shulamit Nussboim, Orah F. Rein Moshe, Johnathan B. Larrone, Elazar Volk, Chaya Sud-Tesler, and Lea Wittenberg

Pesticides are used worldwide to support food security for the growing world population. In Israel thousands of tons of pesticides are applied every year and find their way to the entire catchment: soil, surface water, interflow and groundwater. In addition, the treated waste water applied for irrigation convey pharmaceuticals that are distributed in the catchments as well. Previous studies focused one or a few pollutants, which limit the scope of the chemical features on the pollutants fate. Other research focused a certain flowpaths: the stream and tributaries, or groundwater pollutants. This study provides a wide scope of the all 3 main flowpaths (surface water, interflow, groundwater) and the fate of over 70 pesticides in the field scale, including time series in short temporal resolution for groundwater and interflow.

The study took place during irrigation (Apr 2021) and during winter 2022, focusing two winter storms (Jan 2022). The study fields border the Kishon, the 2nd largest coastal stream in Israel. Both fields have subsurface drainage system to address high water level and bad drainage soils. The subsurface drainage system provides direct approach to the subsurface water. Water collected from the pipe outlet of the system represent subsurface, but also from manholes, which are the approach to the subsurface system. Groundwater was collected from piezometers to deep and shallow aquifers in both fields, according to accepted protocol for ground water sampling, utilizing a metal bailor. Surface water was collected from field surface, applying RCU-Runoff Collector Units and also from secondary and primary surface drainage trenched in the field. All water were collected in glass bottles, and were analyzed by LC/MS.

In this study the spatial distribution in the field scale was demonstrated, including the vertical direction. Samples that were collected from surface water, interflow and groundwater show the dominant flowpath of each compound, where the chemical characteristics were critical to obtain the compound pathway. For example, imidacloprid was applied only a few weeks before the storm and found in high concentration in surface water. Interflow water collected from subsurface drainage system show imidacloprid concentrations which are order of magnitude lower for the entire winter. On the other hand, diflufenican was applied more than two years ago was found in high concentration in surface water, as a result of low degradability and low mobility, yet subsurface concentrations were negligible. Both compounds were in high concentration near the application area (onion section of the field).  Time series (interflow, groundwater) were key data, where taken before, during and after water enter soil column during irrigation or a rain event. All data clustering analysis, showing pairs of compounds vs each other was operated. A clear clustering, in most cases, fit the spatial distribution establishing 4 groups: 1. surface runoff from field and all trenches 2. Subsurface water pipe (and manholes in most cases) 3. Groundwater 4. Stream

This research provides a large data base, including temporal and spatial point of view which are innovative and provide a comprehensive scope for field-scale processes.

How to cite: Nussboim, S., Rein Moshe, O. F., Larrone, J. B., Volk, E., Sud-Tesler, C., and Wittenberg, L.: Agropollutants fate in the fields scale, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-7659, https://doi.org/10.5194/egusphere-egu23-7659, 2023.

EGU23-7699 | Orals | HS2.3.3 | Highlight