HS2.1.4 | Mountain hydrology under global change: monitoring, modelling and adaptation
EDI
Mountain hydrology under global change: monitoring, modelling and adaptation
Convener: Marit Van TielECSECS | Co-conveners: Andrea MomblanchECSECS, David Haro Monteagudo, Daniel Viviroli
Orals
| Mon, 15 Apr, 08:30–12:30 (CEST)
 
Room 2.31
Posters on site
| Attendance Mon, 15 Apr, 16:15–18:00 (CEST) | Display Mon, 15 Apr, 14:00–18:00
 
Hall A
Posters virtual
| Attendance Mon, 15 Apr, 14:00–15:45 (CEST) | Display Mon, 15 Apr, 08:30–18:00
 
vHall A
Orals |
Mon, 08:30
Mon, 16:15
Mon, 14:00
Despite only representing about 25% of continental land, mountains are an essential part of the global ecosystem and are recognised to be the source of much of the world’s fresh water supply. A considerable part of the world’s population depends on this water supply, around 26% live directly in the mountains and 40% live downstream of rivers originating in the mountains. The large elevation ranges and the heterogeneity of elevation-dependent hydro-meteorological conditions make mountains particularly sensitive to climate variability and change, but therefore also unique areas for identifying and monitoring the effects of global change.
This session aims to bring together the scientific community doing hydrology research on mountain ranges across the globe to share results and experiences. Therefore, this session invites contributions addressing past, present and future changes in mountain hydrology due to changes in either climate and/or land use, how these changes affect local and downstream territories, and adaptation strategies to ensure the long-term sustainability of mountain ecosystem services, with a special focus on water cycle regulation and water resources generation. Example topics of interest for this session are:
• Sources of information for evaluating past and present hydrological conditions (in either mountain surface and/or ground water systems).
• Methods for differentiating climatic and anthropogenic drivers of hydrological change in the mountains.
• Modelling approaches to assess mountain hydrological change.
• Evolution, forecasting and impacts of extreme events.
• Case studies on adaptation to changing mountain water resources availability.

Orals: Mon, 15 Apr | Room 2.31

Chairpersons: Marit Van Tiel, Daniel Viviroli
08:30–08:35
08:35–08:55
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EGU24-7718
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solicited
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On-site presentation
Walter Immerzeel and Francesca Pellicciotti

The peak water concept has emerged to represent the trajectory of future water resources from glacierised basins, and has been widely adopted by the glaciology community. This is based on the notion that runoff from glaciers will increase up to a point in the near future and then decrease, because the melt rates of glaciers per unit area increase due to higher temperatures, while glaciers shrink. There is a point in the future that the glacier area becomes so small that the increase in melt rate per unit area cannot compensate for the area loss, and the absolute amount of glacier melt water starts to decrease. This peak water concept has been featured by several prominent papers and by the IPCC. However, we hypothesize that this peak water concept is an oversimplification of reality and can mask the real trajectory of changes in water resources from mountain catchments. It is only a valid concept for a single glacier, and the effect largely disappears when a mountainous catchment consists of multiple glaciers with different size, thickness, and mass balance sensitivity as result of extensive debris cover, for example. Moreover, and more importantly, it ignores climate change impacts on the non-glacierised part of the mountainous catchment, such as the buffering by snow and groundwater storages and the role of vegetation, and shifts in the partitioning between “green” (evapotranspiration) and “blue” (river runoff) water in particular. In this talk, we show a few examples of such oversimplifications, and argue for a broader and holistic perspective on the impacts of climate change on mountain water resources.

How to cite: Immerzeel, W. and Pellicciotti, F.: The peak water myth, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7718, https://doi.org/10.5194/egusphere-egu24-7718, 2024.

Mountain hydrology in High Mountain Asia
08:55–09:05
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EGU24-3373
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ECS
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On-site presentation
Atul Kumar, Suraj Mal, and Udo Schickhoff

The rise in annual mean temperature due to anthropogenic climate change is causing faster melting and thinning of glaciers leading to the formation of new glacial lakes and the expansion of existing ones in the Himalayan region. This exponential growth of glacial lakes increases the availability of freshwater resources and escalates the risk of future Glacial Lake Outburst Floods (GLOFs).
In the present study, Glacial lake inventories for the Upper Ganga basin were generated at the sub-basin level for 1990, 2000, 2010 and 2020 using Landsat (TM and OLI) images and semi-automated methods to understand the evolution of glacial lakes, altitudinal, orientational and typology changes. We were able to map 2,554 (area: 170.15 sq. km) glacial lakes in 1990, 2,783 (area: 191.03 sq. km) in 2000, 2,834 (area: 201.44 sq. km) in 2010, and 3,118 (area: 210.87 sq. km) in 2020. Between 1990 and 2020, the total number of glacial lakes increased by 564 (22.08%) and the total area increased by 40.72 sq. km (23.93%). In the year 2020, glacial lakes were found in 31 sub-basins of the Upper Ganga basin, out of 31 sub-basins, Arun sub-basin had the maximum number of glacial lakes (n: 734 & area: 61.66 sq. km).
The mean elevation of glacial lakes increased from 5,044.81 m asl (1990) to 5,052.30 m asl (2020), showing an increase of 7.49 m asl. In 2020, the majority of the glacial lakes were distributed in the elevation zone of 5,000-5,500 m asl (n:1,404 & area: 113.79 sq. km). In the upper Ganga basin, majority of the glacial lakes were south-facing (491) in 2020.
End moraine-dammed (M(e)) lakes dominate among differnt types of glacial lakes. In 1990, there were 2,081 (M(e)) lakes, which increased to 2,413 in 2020, indicating towards increasing risk of future Glacial Lake Outburst Floods (GLOFs) in the Upper Ganga basin. 
Therefore, the present study provides vital insights into the glacial lake dynamics of the Upper Ganga basin at the sub-basin level and will help in identifying potentially dangerous glacial lakes and developing robust policies to mitigate the impact of future GLOF events.

How to cite: Kumar, A., Mal, S., and Schickhoff, U.: Spatio-temporal evolution of glacial lakes in the Upper Ganga basin, Central Himalayas, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3373, https://doi.org/10.5194/egusphere-egu24-3373, 2024.

09:05–09:15
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EGU24-19825
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ECS
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On-site presentation
Phillip Schuster, Alexander Georgi, Azamat Osmonov, and Tobias Sauter

The impacts of climate change and the retreat of mountain glaciers will significantly affect the headwaters of high mountain river systems. Accurate predictions of future water availability are essential to mitigate local impacts. Despite the availability of various glacio-hydrological modeling tools and high-quality input datasets, their effective application in less developed countries facing severe climate change impacts remains limited. Accessible and cost-effective tools are particularly scarce, hindering engagement with water management stakeholders, especially at the local level.

We present MATILDA, an open-source toolkit for glacierized catchments that allows users to acquire and process public data, apply well-established glacio-hydrological modeling routines, and estimate climate change impacts on the catchment of their choice. The workflow integrates Google Earth Engine, several state-of-the-art online data sources, and calibration algorithms. Published as a Jupyter book, it can be executed in an online Python environment, allowing users to generate scenario-based hydrological projections and analyze trends in runoff contributions, requiring only runoff observations.

The workflow is outlined and discussed in terms of practical application, sensitivity and uncertainty, limitations, and possible improvements. With a view to two regional studies in the Tian Shan Mountains, we evaluate MATILDA’s practical potential to support water management decisions in high mountain areas. The first study assesses the impacts of glacier change on lake levels and local agriculture in the endorheic Issyk-Kul basin in Kyrgyzstan. The second study focuses on the Chirchik River Basin in Uzbekistan and it's crucial role for hydropower production and fresh water supply for the Tashkent metropolitan area.

How to cite: Schuster, P., Georgi, A., Osmonov, A., and Sauter, T.: Assessing Climate Change Impacts on Glacierized Catchments in Central Asia Using an Open Source Toolkit, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19825, https://doi.org/10.5194/egusphere-egu24-19825, 2024.

09:15–09:25
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EGU24-18462
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On-site presentation
Hester Biemans, Arthur Lutz, Wouter Smolenaars, Khalid Jamil, Fulco Ludwig, Sanita Dhaubanjar, and Walter Immerzeel

The high mountains of Asia store large volumes of water in their glaciers and snowpacks. Twelve large river basins, fed with meltwater from these mountains, are home to almost 2 billion people. In their floodplains, a significant fraction of the global food is produced (34% and 23% of the global rice and wheat production respectively). This makes the snow and ice in the High Mountains of Asia a very important water reserve on which both water- and food security for a huge population depend.However, the water supply from the mountains faces many threats. Glaciers and snowpacks are melting at unprecedented rates, and large parts of these reserves are likely to disappear by the end of the 21st century. At the same time, the dependence of downstream populations on mountain water resources is increasing, mainly due to increasing water needs, continuing groundwater depletion and changes in (monsoon) precipitation.Agriculture in the predominantly irrigated floodplains in Asia is very intensive, with often 2 or even 3 crops grown per year. In some of these agricultural areas, irrigation water supply is largely depending on the seasonal availability of meltwater. Any changes in meltwater supply could therefore have large impacts on the crop production, but science has only just started understanding the impacts of melting glaciers and snowpacks on food and water security of downstream populations.In this presentation we will look back on our recent work in which we quantified the current en future dependence of downstream crop production on water from the mountains in the Indus and Ganges basins. We also describe remaining challenges, and look ahead to the upcoming (ERC) 3POLE2SEA project,  that aims to quantify these upstream-downstream linkages in all twelve river basins river basins originating from the High Mountains of Asia. We expect that the 12 river basins have very different upstream-downstream dependencies, resulting in different current and future risks for water and food security, and therefore need different responses for effective adaptation. We explain how our research can contribute to making agriculture in one of the largest food producing areas in the world more resilient to changes in the mountains.

How to cite: Biemans, H., Lutz, A., Smolenaars, W., Jamil, K., Ludwig, F., Dhaubanjar, S., and Immerzeel, W.: Impacts of melting glaciers and snowpacks in High Mountain Asia on downstream water and food security , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18462, https://doi.org/10.5194/egusphere-egu24-18462, 2024.

09:25–09:35
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EGU24-3551
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ECS
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On-site presentation
Yunfei Wang and Aizhong Ye

Runoff from the Tibetan Plateau (TP), known as the Asian water tower, is crucial to regional hydrological processes and the availability of water for large population living downstream. Climate change, especially marked atmospheric warming and altered precipitation patterns, have significantly affected the cryospheric hydrological process in the TP, particularly runoff. However, it is still unclear to what extent precipitation and temperature contribute to runoff change on the TP and the regional variability is not well understood. In this study, a large-scale, high-resolution, and well-calibrated distributed hydrological model was employed to simulate the long-term runoff of the TP over the past six decades (1961-2019). Then, spatiotemporal characteristics of runoff were analyzed. Furthermore, the impacts of precipitation and temperature on runoff variation were quantitatively estimated. The results found that the annual runoff decreased from southeast to northwest, and has been increasing over the past six decades. Notably, precipitation is a more important contributor than temperature across the plateau, contributing 72.08 % and 27.92 % to the runoff change, respectively. Besides, the influence of precipitation and temperature on runoff varies among basins, with the Daduhe Basin and the Inner Basin being the most and least influenced by precipitation, respectively. This research analyses historical runoff changes and provides insights into the contributions of climate change to runoff on the TP, which helps understand the hydrological response to climate change in mountain regions.

How to cite: Wang, Y. and Ye, A.: The quantitative attribution of climate change to runoff increase over the Tibetan Plateau, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3551, https://doi.org/10.5194/egusphere-egu24-3551, 2024.

09:35–09:45
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EGU24-9575
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On-site presentation
Lander Van Tricht, Harry Zekollari, Matthias Huss, Inne Vanderkelen, Marit van Tiel, Loris Compagno, Philippe Huybrechts, and Daniel Farinotti

Glaciers in the Tien Shan act as natural reservoirs, storing freshwater in the form of snow and ice and releasing it during dry periods. This water source serves various purposes and is particularly crucial during dry periods, where it serves agriculture, hydropower, industry, and human consumption. Here, we use GloGEMflow to simulate the future evolution of all glaciers in the Tien Shan under CMIP6 SSP climate scenarios. In all climate scenarios, our results reveal an exceptionally pronounced retreat of the glaciers, surpassing the projected glacier loss for most regions of the world. By 2040, we project a loss of 30% of the glacier mass from 2020, which increases to 60% by 2100 under low emission scenarios (SSP1-1.9, SSP1-2.6) up to 90% under moderate to high emission scenarios (SSP3-7.0 and SSP5-8.5). This drastic retreat is driven by the unique climate of the Tien Shan, with most precipitation occurring during spring and early summer. Rising temperatures not only accelerate glacier melt but also reduce snow accumulation. Regardless of the scenario, we project that peak water from the glacier runoff will occur before 2050. By 2100, total annual glacier runoff decreases by 35% compared to the 2015-2020 mean level. The annual glacier runoff peak shifts from summer, when water demand is highest, to spring, presenting challenges for both agricultural and industrial sectors. We also examine and combine the simulated glacial runoff with information on water availability and demand from the ISIMIP framework. This helps to grasp and evaluate how important glacial meltwater is in the Tien Shan region. Our research provides essential insights for creating adaptive policies to handle water resources effectively at both local and regional level.

How to cite: Van Tricht, L., Zekollari, H., Huss, M., Vanderkelen, I., van Tiel, M., Compagno, L., Huybrechts, P., and Farinotti, D.: Future glacier mass loss in the Tien Shan strongly impacts summer water availability , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9575, https://doi.org/10.5194/egusphere-egu24-9575, 2024.

Mountain hydrology in the Andes
09:45–09:55
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EGU24-6606
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ECS
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On-site presentation
Gavin McNamara, Caroline Aubry-Wake, Lauren Somers, Jeffrey McKenzie, John W. Pomeroy, and Robert Hellström

Glacier melt is known to provide an important source of water to streamflow in glacierized tropical regions, especially during the dry season. Groundwater also contributes a significant amount to streamflow. However, the linkage between the two is often unclear: How much groundwater originates from glacier melt? More broadly, how will groundwater and surface water contributions to streamflow change as glaciers retreat and climate changes? We developed a glacio-hydrological model in the Cold Region Hydrological Modelling platform to explore the complex interactions among the cryosphere, surface water, and groundwater in Peru's Cordillera Blanca, specifically in the Quilcayhuanca valley. The model uses meteorological observations from the valley and is parameterized using numerous data sources and process-based studies in the valley. Our findings reveal that during the dry season, 24 % of streamflow is routed through the groundwater reservoir, increasing to 40 % during the lowest flows. In a simulation without glaciers, streamflow discharge decreases by 34 % during the wet season and by 54 % during the dry season, with the groundwater contribution to streamflow decreasing by 55 % and 52 % for the wet and dry seasons, respectively. This simplified approach suggests that approximately half of the annual groundwater contribution to the stream originates from glacier wastage. We conducted sensitivity scenarios to evaluate the basin's resilience to the range of possible changes in precipitation, temperature and glacier cover expected by 2100. In a nearly deglaciated basin, the sensitivity to the range of tested temperature (+0 to 5 °C) produced a streamflow ranging from -60 to -49 % of current conditions in the dry season, and the range of tested precipitation (-20 % to +20 %) produced a streamflow ranging between -78 to -35 % of current conditions, indicating a larger sensitivity to potential changes in precipitation. Expected ratio changes were smaller during the wet season but followed a similar pattern. In the most likely scenarios by 2100, under RCP 8.5, wet season streamflow is predicted to decrease by 17 to 27 %, and dry season streamflow by 28 to 52 %. Despite a substantial decline in snow and ice contributions under climate change and deglaciation, the groundwater zone's contribution to streamflow shows relatively minor changes, demonstrating the low sensitivity of the groundwater system to climate shifts and glacier variations.

How to cite: McNamara, G., Aubry-Wake, C., Somers, L., McKenzie, J., Pomeroy, J. W., and Hellström, R.: Exploring the connectivity between glacier melt, groundwater and climate change in the Cordillera Blanca, Peru, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6606, https://doi.org/10.5194/egusphere-egu24-6606, 2024.

09:55–10:05
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EGU24-13616
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On-site presentation
James McPhee, Diego Hernandez, Maria Courard, Alonso Mejías, Zelalem Tesemma, Alain Pietroniro, and John Pomeroy

La Niña years are historically associated with precipitation deficits in central Chile. However, since the onset of the so-called Chile Megadrought in 2010, the teleconnection between the El Niño-Southern Oscillation phases and the hydroclimate in central Chile has either weakened or disappeared. This study investigates the hydrological response of high mountain watersheds to La Niña (LN) and megadrought conditions (MD) in the Andes of central Chile (30°S – 35°S) through physically-based simulation of processes at the watershed scale. It is shown that during LN years, winters and summers are colder, but spring seasons are warmer, while in MD years the summers are warmer. In addition, the hydrologic response to LN and MD is distinct and amplified during MD in terms of flow deficit.  Simulation results for five snow-dominated basins within the central Andes suggest lower efficiency in the transformation of precipitation to snowmelt flow (-3.7% and 1.6% with respect to the long-term average, for MD and LN, respectively), accompanied by higher evaporation (8.7% and 6.1%) and lower flow (-9.3% and -3.4%) relative to annual precipitation. Also, snow accumulation deficits at the end of winter propagate (-36.2% and -17.7%) with respect to the deficit of solid precipitation (-29.7% and -17.5%) and total precipitation (-26% and -19.3%), and during the MD the duration of snow is shorter compared to LN (-16.3 and -10.6 days). Thus, the key role played by snow processes and their variability in the hydrological response to droughts in central Chile is highlighted. The findings presented here are expected to inform ongoing discussion on adaptation strategies to climate change, as the observed climate during the megadrought (2010-?) is strikingly similar, on average, to GCM projections for this region toward the end of the 21st century.

How to cite: McPhee, J., Hernandez, D., Courard, M., Mejías, A., Tesemma, Z., Pietroniro, A., and Pomeroy, J.: Hydrological implications of the Chile Megadrought in high mountain basins and lessons for climate adaptation., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13616, https://doi.org/10.5194/egusphere-egu24-13616, 2024.

10:05–10:15
Coffee break
Chairpersons: David Haro Monteagudo, Marit Van Tiel
10:45–10:50
Mountain hydrology in the European Alps
10:50–11:10
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EGU24-4133
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ECS
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solicited
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On-site presentation
Anna Herzog, Klaus Vormoor, and Axel Bronstert

In alpine catchments, evapotranspiration (ET) is regularly considered a minor component of the hydrological system and is therefore only rudimentarily regarded in modelling studies and climate change projections. The focus is usually on snow and glacier related processes, projecting a rapid retreat of glaciers in central Europe within the next few years and decreasing snow volumes at lower elevations due to climate warming. This leads to a reduction in the dominance of snow and glacier related processes. Changes in vegetation characteristics due to climate- and/or land use change will presumably lead to a relative increase in the importance of other processes such as ET, interception and soil moisture, which will affect spatial and temporal variations in discharge generation.

To identify spatial and temporal patterns of changing process importance, a case study of the Fundusbach catchment in Tyrol, Austria is conducted using the fully distributed and physically based model WaSiM-ETH. As the process representation within all hydrological models is affected by parameter equifinality, substantially different parameter combinations and therefore process representations can lead to similar values of performance criteria when looking at discharge only. To address this issue, elevation dependent, spatial and temporal parameter sensitivity analysis is coupled with a multi-objective calibration. This approach aims to improve the spatial and elevation dependent process representation within the model domain. Instead of calibrating on different output variables, additional field and remote sensing data are used to constrain the parameter space of individual submodels and thus the process behaviour. In a final step, the constrained model is calibrated against discharge. Based on this reference model, scenario analyses are carried out to investigate individual process responses to changes in climate and land use.

The results show, that integrating additional field data and constraining the calibration parameter space considerably improves the process representation within the model. Furthermore, first results show, that changes of the land cover do not influence the overall discharge regime, but ET and soil moisture. Increasing amounts of shrub cover limit infiltration and evaporation, while interception and soil moisture increase. Most process responses intensify with increasing elevation and reflect the spatial patterns of land cover.

How to cite: Herzog, A., Vormoor, K., and Bronstert, A.: Shifting hydrological process importance in alpine catchments: Combined effects of climate and land cover change on alpine evapotranspiration, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4133, https://doi.org/10.5194/egusphere-egu24-4133, 2024.

11:10–11:20
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EGU24-10041
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ECS
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On-site presentation
Klaus Vormoor, Till Francke, Anna Herzog, and Axel Bronstert

Snowmelt or ice melt typically control diurnal streamflow cycles during rain-free periods in high-altitude alpine catchments. Evapotranspiration-controlled streamflow cycles are less prominent, but can occur simultaneously (Mutzner et al., 2015). In general, the importance of evapotranspiration for the water balance of alpine catchments is likely to increase due to changing atmospheric boundary conditions and (related) changes in land cover. In this study, we focus on controls of diurnal streamflow cycles in the Fundusbach catchment (13 km²) in the Ötztal Alps (Austria). In addition to the official gauge at the catchment outlet, we have installed three further gauges along the longitudinal river profile. Here, we are recording the variability in water level/discharge at high temporal resolution (15 min) since June 2022. We have also adapted the deterministic spatially distributed hydrological model WaSiM with hourly and high spatial resolution (25 x 25 m²) for the Fundusbach catchment. Based on this model and the observation data, we are able to

  • determine the diurnal streamflow dynamics and their change along the longitudinal profile,
  • analyze the seasonal dynamics of diurnal streamflow patterns, and thus,
  • draw conclusions about the spatially and temporally changing control variables of the diurnal streamflow cycles (data- and model-attributed) for rain-free periods outside winter.

Results show that (i) the diurnal streamflow variability decreases along the longitudinal profile, (ii) the amplitude of meltwater driven runoff cycles decreases exponentially over the year, whereby (iii) evapotranspiration-driven cycles always seem to attenuate meltwater-driven cycles. At later points in the snow-free season, the signal of the evapotranspiration-induced streamflow cycles can occasionally be inferred directly from the measurement data. For these days, catchment evapotranspiration amounts can be determined from runoff data as the integral between the daily maximum (during nighttime) and minimum (during daytime). The results also indicate an altitude-dependency of the control processes along the longitudinal profile, which needs to be further investigated.

Reference:

Mutzner, R., Weijs, S.V., Tarolli, P., Calaf, M.C., Oldroyd, H.J., Parlange, M.B. (2015): Controls on the diurnal streamflow cycles in two subbasins of an alpine headwater catchment. Water Resour. Res., 51, 3403-3418. doi.org/10.1002/2014WR016581.

How to cite: Vormoor, K., Francke, T., Herzog, A., and Bronstert, A.: Control processes of diurnal streamflow cycles along the longitudinal profile of an alpine river, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10041, https://doi.org/10.5194/egusphere-egu24-10041, 2024.

11:20–11:30
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EGU24-2269
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ECS
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On-site presentation
Xinyang Fan, Florentin Hofmeister, Bettina Schaefli, and Gabriele Chiogna

Groundwater plays a pivotal role in the water cycle but its interplay with hydrological processes has often been neglected or overly simplified in hydrological models of high-elevation catchments. This may increase uncertainties in future projections and impede a holistic understanding of the hydrological changes. High Alpine catchments, in fact, display complex surface and subsurface processes and lack of observations. Here, we investigate the role of alpine groundwater in the hydrologic response by partitioning the observed streamflow variations to glacier recessions, snowmelt, rainfall, and for the first time - groundwater fluxes at the Martell valley in Italy since the 2000s. To examine the dynamic interactions of these components in detail, we adopt a modeling framework that combines the physics-based model WaSiM (with an integrated groundwater module) with meteorological inputs obtained from the weather model WRF. Extensive field observations (meteorology, hydrology, geomorphology, piezometric levels, stable water isotopes) are collected to constrain the hydrological model parameters and for model evaluation. This study quantifies the contribution of groundwater in moderating the intensity and timing of hydrological extremes (high and low flows) in the selected high-elevation catchment and emphasizes the significance of groundwater in sustaining water availability in this sensitive environment subject to climate change.

How to cite: Fan, X., Hofmeister, F., Schaefli, B., and Chiogna, G.: Role of groundwater during hydrological extremes in the glaciated and snow-fed high Alpine catchment under climate change, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2269, https://doi.org/10.5194/egusphere-egu24-2269, 2024.

11:30–11:40
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EGU24-17858
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ECS
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On-site presentation
Filip Paul Boanca, Magdalena Seelig, Clemens Karwautz, Winkler Gerfried, and Christian Griebler

Springs are vital water sources, and their vulnerability to environmental changes, particularly climate change, is of growing concern. The collaborative research project ECOSPRING, funded by the Austrian Academy of Sciences, focuses on the assessment of microbial communities and water quality patterns in selected springs all over Austria. Here, we will focus on understanding the response and vulnerability to hydrological events and climate change.

The first aim of the project is to characterize the springs based on their temporal dynamics in terms of physical-chemical characteristics. A detailed analysis of the dynamics in discharge, temperature, pH, EC, stable isotopes, essential nutrients, and major ions will provide valuable insights into the geological imprint and prevailing hydrological conditions, as well as on catchment areas.

Microbes are an integral component of aquatic ecosystems and can serve as sensitive indicators for environmental conditions. We will compare the microbial community composition in relation to the hydrogeological and physicochemical conditions.

Our research activities target two spatial scales, from a local perspective, with 14 springs in the province of Styria studied monthly, to a regional approach by sampling around 100 springs distributed all over Austria twice, in winter/spring and summer/autumn marking the expected hydrological extremes.

In the initial stages of our research, we gathered data from 15 selected springs of Styria. These springs exhibit a wide and dynamic spectrum in their physical-chemical properties. Together with records of discharge, springs could be categorized into stable, intermediate, and highly dynamic systems. Our preliminary results indicate a connection between these fluctuating physical-chemical conditions and the composition of the spring water microbiome. The underlying mechanisms driving these observed patterns are yet not fully understood and await further investigations.

In summary, this research project seeks to enhance our understanding of the vulnerability of spring waters to anthropogenic pressures such as climate change. The findings will provide a knowledge base for future water resources management and contribute to the sustainable use of these vital resources.

How to cite: Boanca, F. P., Seelig, M., Karwautz, C., Gerfried, W., and Griebler, C.: Temporal dynamics of water quality and microbial community composition in alpine springs, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17858, https://doi.org/10.5194/egusphere-egu24-17858, 2024.

Mountain hydrology in Africa
11:40–11:50
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EGU24-11621
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ECS
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On-site presentation
Karima Nifa, Abdelghani Boudhar, Haytam Elyoussfi, Youssra Eljabiri, Mostafa Bousbaa, Bouchra Bargam, and Abdelghani Chehbouni

This study thoroughly compared two types of neural networks, namely Long Short-Term Memory (LSTM) and Gated Recurrent Unit (GRU) recurrent neural networks (RNNs), within the context of hydrological modeling for predicting runoff in the Oum Er Rabia sub-basins. By assessing their performance on both daily and monthly scales, we aimed to understand the dynamics of runoff, which is crucial in water resources management. The combined analysis of predictions at both time scales provides a comprehensive perspective, using daily outputs for short-term decisions and monthly predictions for longer-term planning.

Using a hydroclimatic time series dataset from 2000 to 2019, incorporating key factors such as snow cover area, temperature, and rainfall that influence hydrological processes and significantly impact flow patterns, the research evaluates the predictive accuracy of the models at both scales. The results reveal nuanced differences in predictive accuracy, with average Kling-Gupta Efficiency (KGE) values for LSTM and GRU at daily and monthly scales, respectively, being 0.64, 0.52, and 0.46, 0.54. These findings provide insights into the strengths and limitations of each architecture in the mountainous region of Morocco.

The study enhances our understanding of the applicability of LSTM and GRU architectures in hydrological modeling, aiding practitioners in selecting models tailored to specific needs. By establishing a robust framework for short-term decision-making and long-term planning in water resource management, this research contributes to advancing predictive modeling and promoting sustainable water use while mitigating flood risks. The knowledge acquired paves the way for improved decision support in the critical area of water resource management.

How to cite: Nifa, K., Boudhar, A., Elyoussfi, H., Eljabiri, Y., Bousbaa, M., Bargam, B., and Chehbouni, A.: Exploring Neural Network Performance in Hydrological Modeling in a Mountainous Region of Morocco: A Case Study on LSTM and GRU Architectures for Runoff Prediction, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11621, https://doi.org/10.5194/egusphere-egu24-11621, 2024.

11:50–12:00
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EGU24-14594
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ECS
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On-site presentation
Mohamed El Garnaoui, Abdelghani Boudhar, Ismail Karaoui, and Abdelghani Chehbouni

In North African countries where water scarcity and limited data prevail, employing predictive hydrological modeling is crucial to gain accurate insights into current and future water reserves. Hence, these models parameters exhibit instability in this context due to the climate variability observed through basins. Therefore, our efforts focus on using a combination of measured data, remote sensing information, and reanalysis data for calibration and validation, to check the improvement in the result accuracy. Through this study, we simultaneously investigate the spatiotemporal stability of the HBV model in several sub-catchments of Oum Er-Rbia Basin, by improving the performance of a bucket-type conceptual model. We created a Nested Cross-Validation (NCV) framework to assess spatiotemporal stability. The framework uses optimal parameters from a donor catchment of the Hydrologiska Byråns Vattenbalansavdelning (HBV) model as inputs for target catchment parameter ranges. In particular, we evaluated HBV's capacity for prediction over time and space, as well as its impact on model parametrization throughout the regionalization process in the setting of sparse data catchments. As results, the HBV model is spatially transferable from one basin to another, with NSE ranging from  0.5 to 0.8 and KGE values between 0.1 to 0.9, meaning a moderate to high performance. The HBV optimum parameter sets exhibit unpredictable behavior over space. On the contrary, their inter-annual behavior is nearly identical. It also detected a decrease in the model's predictive skills over time, which can be explained by the research area's tendency to dry out year after year. Furthermore, employing KGE for calibration rather than NSE improves model predictive performance significantly. The model  calibration process with the KGE outperformed those with the NSE metric, especially when simulating high flows. Furthermore, the findings demonstrate a significant relationship between high model performance and high values of several optimal parameter sets throughout the calibration and validation periods.

Keywords: HBV model, poorly gauged basin, arid and semi-arid region, KGE, NSE.

How to cite: El Garnaoui, M., Boudhar, A., Karaoui, I., and Chehbouni, A.: HBV Performance under complex and poorly gauged context, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14594, https://doi.org/10.5194/egusphere-egu24-14594, 2024.

Mountain hydrology in other regions
12:00–12:10
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EGU24-10334
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ECS
|
On-site presentation
Sarah Hanus, Peter Burek, Mikhail Smilovic, Jan Seibert, and Daniel Viviroli

Mountainous areas play a crucial role in global water resources. Orographic precipitation provides mountains with disproportionately high precipitation, which can be stored seasonally or over many years as snow and ice. Therefore, mountains are often referred to as ‘water towers’, emphasising their vital contribution to water provision for human use. Nevertheless, on a global scale, knowledge about their relevance for lowlands is limited, especially beyond long-term annual averages (Viviroli et al., 2020). Therefore, this study aimed to first assess differences in the water supply of mountains and lowlands in large river basins globally. Second, the share of mountain runoff in lowland water abstractions was evaluated with a focus on monthly averages and intra- and interannual variability to identify hotspots of mountain importance.

Our study is based on global simulations of the large-scale hydrological model CWatM (Burek et al., 2020) at a resolution of 5arcmin (~10km) from 1990 to 2019. The model simulates water availability, water demand and water use. A glacier representation was added to depict mountain water resources more realistically (Hanus et al., submitted). We compared water availability and demand in mountain and lowland areas within each river basin to identify the distinct patterns regarding water quantity, seasonality and interannual variability in mountains. Additionally, we derived the share of mountain runoff in lowland surface water abstractions to explore the relevance of mountains for human water use.

The analysis of around 600 river basins globally confirmed that precipitation and runoff are disproportionally higher in mountain areas in most river basins, whereas water demand is comparatively low. Additionally, we found mostly a larger intra-annual variability and lower interannual variability in mountain runoff compared to lowland runoff.

The estimated share of mountain runoff in lowland surface water abstractions is largest in High Mountain Asia, western North America, parts of South America and Southern Europe. In 250 basins, the maximum monthly relative mountain runoff share in lowland surface water abstractions exceeds 10%, and 25% of the world population lives in the lowlands of these basins. In comparison, only 7% of the world's population lives in lowlands of basins where the long-term mean annual share of mountain runoff in lowland surface water abstractions exceeds 10%. Thus, the relevance of mountains for lowland water supply becomes more apparent when distinguishing between different months compared to long-term annual averages.

Burek, P., Satoh, Y., Kahil, T., Tang, T., Greve, P., Smilovic, M., Guillaumot, L., Zhao, F., and Wada, Y.: Development of the Community Water Model (CWatM v1.04) – a high-resolution hydrological model for global and regional assessment of integrated water resources management, Geosci. Model Dev., 13, 3267–3298, https://doi.org/10.5194/gmd-13-3267-2020, 2020.

Viviroli, D., Kummu, M., Meybeck, M., Kallio, M., & Wada, Y.: Increasing dependence of lowland populations on mountain water resources. Nature Sustainability3(11), 917-928, https://doi.org/10.1038/s41893-020-0559-9, 2020.

How to cite: Hanus, S., Burek, P., Smilovic, M., Seibert, J., and Viviroli, D.: What is the monthly share of mountain water in lowland water abstractions?, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10334, https://doi.org/10.5194/egusphere-egu24-10334, 2024.

12:10–12:20
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EGU24-4160
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On-site presentation
Matthew Miller, Natalie Day, Jesse Dickinson, John Engott, Casey Jones, Jacob Knight, Patrick Longley, Samuel Lopez, Melissa Masbruch, Morgan McDonnell, Olivia Miller, Noah Schmadel, Fred Tillman, and Daniel Wise

The lack of comprehensive water supply prediction capacity in most areas of the U.S. poses challenges in evaluating water availability. In order to improve water availability prediction and assessment, in 2019, the U.S. Geological Survey initiated planning efforts to intensively study five medium-sized basins throughout the U.S. over the next decade, including the Upper Colorado River Basin (UCOL). Research in the UCOL aims to provide insight into how past, present, and future snow conditions – including amount, timing, melt, and transitions from snow- to rain-dominated systems – impact water supply (quantity and quality) and the ability to meet demand. A specific emphasis is placed on how these processes affect water budget components and dissolved solids concentration and loading in the UCOL. A fully integrated groundwater-surface water hydrologic model (GSFLOW), and temporally dynamic dissolved solids models (SPARROW) that explicitly represent the groundwater contribution to dissolved solids loading to streams are being applied to meet the study objective. Comprehensive information on water diversion and groundwater pumping has been compiled and is being explicitly represented in the models to better represent human demand.  Temporal and spatial patterns in predicted water quantity and quality conditions are being evaluated in the context of past and projected future changes, summarized over 30-year time periods, in snow metrics.  Historical trends in multiple snow metrics, water budget components, groundwater levels, and dissolved solids provide context for evaluations of current conditions and motivation for further investigation and modeling. The tools and concepts developed in the UCOL will contribute to ongoing work in the other regional study basins as well as a forthcoming national water availability assessment. 

How to cite: Miller, M., Day, N., Dickinson, J., Engott, J., Jones, C., Knight, J., Longley, P., Lopez, S., Masbruch, M., McDonnell, M., Miller, O., Schmadel, N., Tillman, F., and Wise, D.: Water Availability Assessment in the Upper Colorado River Basin, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4160, https://doi.org/10.5194/egusphere-egu24-4160, 2024.

12:20–12:30

Posters on site: Mon, 15 Apr, 16:15–18:00 | Hall A

Display time: Mon, 15 Apr 14:00–Mon, 15 Apr 18:00
Chairpersons: Daniel Viviroli, David Haro Monteagudo
Mountain groundwater
A.14
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EGU24-6691
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ECS
Groundwater recharge from the Moroccan Atlas mountains and implications on current and future water resources
(withdrawn after no-show)
Yassine Ait Brahim, Hamza Berrouch, and Lhoussaine Bouchaou
A.15
|
EGU24-3824
Jeffrey Munroe, Matthew Morriss, Greg Carling, Debra Finn, Lusha Tronstad, and Scott Hotaling

The global cryosphere is rapidly changing in response to climate warming.  Rock glaciers may be more resilient to climate change than their surface ice and snow counterparts.  However, unlike surface ice features, rock glaciers are comprised of complex mixtures of ice and locally sourced rock, which may be tightly connected to local hydrologic conditions.  This close hydrogeologic connection appears to underlie substantial variability in the environmental conditions of streams associated with rock glaciers, even within the same geographic region.  Here, we analyze 13 years of field data (2011-2023) from 10 rock glaciers and 13 related ice features from four mountain ranges in Wyoming and Utah, USA, to characterize the environmental and geochemical landscape of their outflows.  Specifically, we compare water temperature, geochemistry, conductivity, and isotopic signatures (δ18O and δD) across mountain ranges and ice features.  We find an average surface water temperature of 0.97 ± 1.1 °C across all 10 rock glacier sites from all 13 years; -0.80 ± 0.82 °C at five glacier fed sites, and 1.21 ± 1.88 °C at six snowmelt fed sites.  Preliminary data from two summers of observations also reveal a consistent positive trend in specific conductivity of two rock glacier-fed streams, typical of water transitioning from snowmelt-dominated to ice-melt dominated sources.  Our results highlight the considerable variability in these ecosystems, even within mountain ranges, and underscore the need for wider sampling to better contextualize and monitor them in the future.  This context is critical when considering whether rock glaciers will promote resiliency of coldwater habitat under climate change, and the degree to which their contribution to alpine hydrologic systems may affect biodiversity and drinking water quality as contributions from snow and glacier ice decrease.

How to cite: Munroe, J., Morriss, M., Carling, G., Finn, D., Tronstad, L., and Hotaling, S.: Characterizing the environmental and geochemical landscape of rock glacier outflows in the Intermountain West, USA, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3824, https://doi.org/10.5194/egusphere-egu24-3824, 2024.

A.16
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EGU24-13828
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ECS
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Poulomee Coomar, Suhail Lone Ahmed, Gh Jeelani, Saibal Gupta, and Abhijit Mukherjee

The upper Indus River basin aquifers spanning over the Himalayan, Karakoram, Hindu Kush ranges is a vast water scares region, which have escaped the notice of the groundwater scientists until recently. The work presented here aims to decipher the processes of groundwater-rock interactions in the shallow Trans-Himalayan Indus River basin aquifers of India. Located on the Indus-Tsangpo suture zone, the area provides a unique opportunity to study water-rock interaction processes in one of the coldest and highest inhabited regions of the world.

Alkaline to circumneutral groundwater are collected from wells mostly located in the meta basics and associated volcanoclastic of the Dras Volcanics (DV) and the granitoids and their extrusive equivalents of the Ladakh Plutonic Complex (LPC). Waters mostly belong to Ca-HCO3 and Ca-Mg-HCO3 facies. Ca-Na-HCO3 occurs as minor facies. Among bivalent cations Ca and Mg shows high degree of correlation, with a low Ca/Mg ratio. Ca-Mg-HCO3 relations suggest bivalents come from Ca-Mg pyroxenes and calcite of the meta-basalts, and calcic plagioclase. Ca-Mg pyroxenes are sourced from the DV, while Ca-feldspars only from the LPC, given the ones in DV are albitised. Decreasing trends of calcite saturation with Ca/Mg ratio hints secondary calcite precipitation. Among monovalent ions, Na + K versus SO42- + Cl- relations suggests, waters owe their Na content to silicates or cation exchange reactions when the ratio >1, and to inputs from saline springs or compounds when the ratio falls below unity. Nearly 60% of samples have Na in excess of Cl- (Na*), but only a minority of them correlates well with dissolved silica. However, thermodynamic calculations suggest waters are mostly in equilibrium with kaolinite, along with some Ca -, Na – smectites and in disequilibrium with all sorts of feldspars suggesting both Na- and K-feldspar weathering from both meta-basics and felsic lithologies. The absence of Na*-Si correlativity indicates simultaneous Na addition through ion-exchange processes or dissolution of non-halite hydrothermal precipitates; borax, trona, burkeite, being the most common. Lack of co-relation between Cl- and SO42- suggest dissimilarity in their provenance.  High Ca/ SO42- ratio precludes inputs from gypsum or anhydrite, so SO42- can only stem from sulphide oxidation or dissolution of sulphates like thenardite or jarosite, which are known to occur in vicinity of local hot springs.

 

How to cite: Coomar, P., Ahmed, S. L., Jeelani, G., Gupta, S., and Mukherjee, A.: Geological controls on groundwater chemistry in the Himalayan Indus River basin aquifers, India, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13828, https://doi.org/10.5194/egusphere-egu24-13828, 2024.

A.17
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EGU24-3961
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ECS
Sebastian Gnann, Jane Baldwin, Mark Cuthbert, Tom Gleeson, Wolfgang Schwanghart, and Thorsten Wagener

Topography affects the distribution and movement of water on Earth, but exciting puzzles remain and new discoveries regarding topographic controls continue to surprise us. In this contribution, we discuss some open questions regarding the influence of topography on the terrestrial water cycle based on a combination of literature review and data synthesis. How will changes in water and energy supply along elevation gradients translate into changes in actual evaporation, and how will this be modulated by plant physiological responses and topographically driven moisture redistribution? What role does groundwater play in sourcing the world's water towers, and how will this role change with melting of snowpacks and glaciers? What is the relative importance of topography (vs. climate and geology) in driving groundwater flow dynamics across scales, and how does topography influence inter-catchment groundwater flow or mountain block recharge? A key feature emerging from these questions is the presence of numerous interacting gradients and contrasts that explain many of the patterns we observe. Studying these interactions, and thus answering at least some of the questions posed above, has the potential to improve our understanding of hydrological systems and how they may evolve in the wake of global change.

How to cite: Gnann, S., Baldwin, J., Cuthbert, M., Gleeson, T., Schwanghart, W., and Wagener, T.: Open questions regarding the influence of topography on the terrestrial water cycle, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3961, https://doi.org/10.5194/egusphere-egu24-3961, 2024.

A.18
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EGU24-18832
Matevž Vremec, Magdalena Seelig, Simon Seelig, Raoul Collenteur, Thomas Wagner, Jutta Eybl, and Gerfried Winkler

Alpine spring runoff patterns recorded at gauging stations offer a unique observational window into the hydrological state of Alpine water systems. These systems play a crucial role in supplying water to downstream areas and are particularly sensitive to changes in temperature and precipitation. Using a dataset of spring discharge monitored at 29 stations by the Austrian Hydrographic Service, spanning 24 years, we conducted a trend analysis on both the quantity and timing of mean and extreme flows. The springs, which were clustered into groups based on the Pardé coefficient and autocorrelation analysis, are distributed over the whole area of the Austrian Alps with mean catchment elevation reaching up to 2500 m above sea level. The trend analysis was performed using the Mann-Kendall test and the Theil-Sen slope on seasonally and annually computed statistics describing the quantity and timing of the occurrence of mean and extreme flows. The results indicate that at springs with a nival flow regime (i.e., flow dominated by snow melt), winter discharge increased. However, during the summer period, differences emerged between two characteristic spring groups: (i) springs at higher-elevation catchments, mainly distributed in the west of the Austrian Alps, with a positive trend in summer, and (ii) springs in the eastern part of the Northern Alps, that displayed a decrease in summer discharge. Notably, differences in the trends for timing of maximum and minimum flows were also evident between these two groups. Furthermore, we compared the hydrological trends to precipitation trends in the spring areas to assess relationships between meteorological and hydrological patterns. These findings provide valuable insights into how the spring runoff patterns have evolved in the Austrian Alps over the past 24 years.

How to cite: Vremec, M., Seelig, M., Seelig, S., Collenteur, R., Wagner, T., Eybl, J., and Winkler, G.: Changing discharge patterns of springs characterized by nival flow regimes in the Austrian Alps, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18832, https://doi.org/10.5194/egusphere-egu24-18832, 2024.

A.19
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EGU24-17796
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ECS
Magdalena Seelig, Simon Seelig, Matevž Vremec, Thomas Wagner, and Gerfried Winkler

Spring catchments in Austria are frequently located in alpine regions that are strongly exposed to the effects of global warming. To predict their impact on spring flow, the delineation of hydrological catchments establishes the link between atmospheric input, catchment characteristics, and aquifer properties. This study proposes a delineation methodology that combines a lumped-parameter model with the analysis of stable isotope data. The model includes a semi-distributed snow module (CemaNeige) and a rainfall-runoff model (GR4J), which were applied iteratively to a set of potential catchments of varying extent and location to simulate spring flow. Constraining the models by spring flow data and remote sensing of snow cover distribution allowed us to differentiate plausible catchments from implausible ones. The mean catchment elevation was estimated based on stable hydrogen and oxygen data collected monthly at the springs. The proposed methodology was tested at two karst springs draining geologically complex catchments in different mountain ranges of the Northern Calcareous Alps, where the hydrological catchments deviate strongly from the orographic ones. The catchments lie mainly in mountainous plateau regions that are characterized by high altitudes and long-lasting snow cover. The model results and isotope analysis are in line with additional, independent information based on tracer experiments, structural geology, and speleology. The proposed methodology provides a quantitative, model-based approach to delineate plausible spring catchments in high alpine and complex hydrogeological settings. It thus forms the knowledge base for sustainable management of alpine freshwater resources under a changing climate.

How to cite: Seelig, M., Seelig, S., Vremec, M., Wagner, T., and Winkler, G.: A model-based methodology for the delineation of complex alpine spring catchments, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17796, https://doi.org/10.5194/egusphere-egu24-17796, 2024.

A.20
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EGU24-4092
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ECS
Marit Van Tiel, Caroline Aubry-Wake, and Lauren Somers and the Mountain cryosphere-groundwater interactions working group

Both the mountain cryosphere -- comprising glaciers, snow, and permafrost -- and groundwater play crucial roles in shaping the hydrological cycle. However, their connectivity is not well understood. Understanding the importance of sub-surface meltwater flowpaths and the role of groundwater in mountain regions is critical to untangle 1) the fate of meltwater in the hydrological cycle and 2) the sensitivity of groundwater to a changing meltwater supply due to climate change.

Here, we synthesize studies which investigated the dynamics of meltwater flow through mountain aquifers. In general, snow-groundwater connectivity is better described than glacier-groundwater connectivity. However, estimations of meltwater recharge fluxes vary considerably across studies, which is not only a function of inherent catchment characteristics but also of the different methods used for the assessments. Estimates of the source contributions of mountain groundwater range between 2-60% for glacier melt and between 40-80% for snowmelt. These large numbers suggest that cryosphere-groundwater connectivity and the consequent delay in meltwater flow needs to be part of our conceptual understanding of the mountain water cycle. Still, there is a clear lack of understanding at which spatio-temporal scales this connection operates.

As glaciers retreat and snowpack diminishes, the relative importance of groundwater as catchment storage is expected to increase. This increase may however be partly compromised by declining recharge from the mountain cryosphere and changed recharge dynamics, with yet unknown effects on catchment-scale hydrological processes. We suggest a roadmap for future work to better quantify mountain cryosphere-groundwater connectivity and to predict climate change impacts on mountain water supplies.

How to cite: Van Tiel, M., Aubry-Wake, C., and Somers, L. and the Mountain cryosphere-groundwater interactions working group: Cryosphere-groundwater connectivity in the mountain water cycle - where does meltwater go?, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4092, https://doi.org/10.5194/egusphere-egu24-4092, 2024.

Droughts
A.21
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EGU24-11313
Pascal Buri, Michael McCarthy, Simone Fatichi, Philipp Brun, Dirk Karger, Liangzhi Chen, Massimiliano Zappa, Evan S. Miles, Thomas E. Shaw, and Francesca Pellicciotti

During dry and hot years in the Swiss Alps, melt water from glaciers can moderate streamflow deficits caused by reduced precipitation and enhanced evapotranspiration rates. However, little is known about how glacier melt water contribution to streamflow varies sub-seasonally and in space, especially further downstream from glacierized catchments, where additional streamflow contributions are modulated primarily by rainfall and the biosphere (vegetation, soils).

We study distributed catchment hydrology in Switzerland using a land surface model that constrains energy and mass fluxes using advanced physical representations of both cryospheric and biospheric processes at a 250 m spatial resolution. We simulate catchment runoff in Switzerland during the past 6 years, including two recent severe drought years (2018 and 2022), characterized by particularly warm summers and reduced precipitation. The model is forced with hourly observed meteorological data based on the weather station network SwissMetNet and the precipitation product RhiresD, and uses state-of-the-art land cover, soil characteristics, glacier area and debris thickness as initial conditions.

The spatially explicit simulations allow, when temporally aggregated, to trace upstream contributions of individual water balance components for any downstream point in the catchment. We use the model to quantify the amount and timing of glacier melt and how it affects downstream runoff composition, especially during drought conditions, along the river network. We do this across regions from the Swiss Alps’ headwaters to the lowlands in a spatially continuous way.

When comparing runoff composition during moderate summer months to periods of drought conditions in the Swiss Alps, our simulations show both an increase in intensity and downstream propagation of ice melt contribution to total runoff. During extreme drought periods, ice melt makes up >70% of streamflow (~doubling the contributions during more moderate periods) in some of the Alps’ headwater regions (>1500 m a.s.l.), and still exceeds 10% of streamflow contribution downstream of the pre-alpine region.

Quantifying the timing and amount of glacier melt contributions to downstream water resources under recent drought conditions improves our understanding of potential cryosphere-biosphere interactions and their impacts under future extreme scenarios, when cryospheric runoff contributions may be reduced or completely lost.

How to cite: Buri, P., McCarthy, M., Fatichi, S., Brun, P., Karger, D., Chen, L., Zappa, M., Miles, E. S., Shaw, T. E., and Pellicciotti, F.: Spatially distributed streamflow buffering by glaciers during recent droughts in Switzerland, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11313, https://doi.org/10.5194/egusphere-egu24-11313, 2024.

A.22
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EGU24-14340
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ECS
Pranisha Pokhrel, Sonu Khanal, Jasper Griffioen, Thom A. Bogaard, and Walter Immerzeel

The Karnali basin (40,000 sq km) in western Nepal is a pristine river basin with large potential for the development of hydropower and irrigation. The Karnali river sustains the biodiversity in the national parks downstream and supports the livelihoods of thousands of people. Any changes in the flow regime of the Karnali may therefore have far reaching consequences. This study focuses on analyzing the hydrological response of the Karnali to (multi-year) droughts. The objective is to understand how long the storages in the hydrological system, e.g. glaciers, snow, ground and soil water can buffer prolonged droughts. The hydrological model SPHY, calibrated with long-term river flow observations, is used for this purpose. We created synthetic drought time series by sampling from a 30-year historical forcing dataset based on ERA5. We then used these time series to force the SPHY model and we analyzed the change in streamflow composition as a function of drought duration. This study provides important insights in the buffering capacity of the river basin in a changing climate.

How to cite: Pokhrel, P., Khanal, S., Griffioen, J., Bogaard, T. A., and Immerzeel, W.: Hydrological response to droughts in the Karnali basin of Nepal, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14340, https://doi.org/10.5194/egusphere-egu24-14340, 2024.

Climate change impacts on mountain hydrology
A.23
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EGU24-6458
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ECS
Luca Lombardo, Juraj Parajka, Peter Valent, and Alberto Viglione

The worsening of global climate change has increased both the frequency and intensity of extreme weather events, significantly impacting the dynamics of flooding. This convergence of factors results in intensified and prolonged precipitation, leading to river overflow and catastrophic floods. Elevated temperatures and rapid snowpack melting further contribute to the increase of flood risk. These impacts are particularly pronounced in mountainous regions, where the combination of steep terrain and increased precipitation amplifies the risk of flash and snowmelt generated floods.

The CLIM2FLEX project aligns with this intricate and evolving context, aiming to assess, under potential climate scenarios, the variations in the frequency and intensity of river floods generated by various mechanisms. Within the project framework, a crucial aspect involves constructing a modeling chain, complete with a hydrological module. This component is dedicated to translating climate inputs into continuous discharge time series, enhancing the project's capacity for in-depth analysis and dynamic modeling.

To do so, the main idea is to use a "new version" of the "TUWmodel" conceptual hydrological model to account for the inter-basin transfer of water and flood waves propagation (from upstream catchments to downstream catchments) through the implementation of a new routing routine based on the introduction of a Nash-Cascade module. Different calibration strategies are used at gauged sites to estimate the best model parameters. A machine learning based regionalization approach (HydroPASS) is then applied to infer model parameters at ungauged sites for hydrological streamflow predictions. 

The focus of this study encompasses the entire Great Alpine Region (GAR), posing significant modeling challenges. The region is predominantly characterized by mountainous terrain, consisting mainly of small catchments. Here, the effects of snow accumulation-melting cycles, as well as the presence of glaciers and other small-scale features, play a particularly crucial role.

The presentation at EGU will delve into preliminary findings concerning the applicability and reliability of the proposed hydrological modeling chain structure, along with the anticipated future steps in the research.

How to cite: Lombardo, L., Parajka, J., Valent, P., and Viglione, A.: A distributed rainfall-runoff model for the investigation of climate change effects on river floods in the European Alps, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6458, https://doi.org/10.5194/egusphere-egu24-6458, 2024.

A.24
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EGU24-14840
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ECS
Jiayong Shi, Juraj Parajka, Jianyun Zhang, Guoqing Wang, and Zhenxin Bao

This study presents a comprehensive analysis of the hydrological changes in the Yellow River source region, a key component of the Qinghai-Tibet Plateau's Three-River Source Region. During the period 1960-2020, we observed a significant increase in precipitation but paradoxically, a slight decrease in runoff. The region, characterized by its critical positioning at the boundary of permanent and seasonal permafrost, has undergone substantial environmental changes due to global warming. By integrating historical data and multi-source remote sensing, our research dissects the complex interactions between the altered permafrost, snow cover, and vegetation dynamics. We specifically examine how these changes influence the regional hydrological cycle, particularly focusing on the mechanisms leading to reduced runoff despite increased precipitation. Our findings provide novel insights into the impacts of climate change on high-altitude hydrological systems. They hold significant implications for water resource management and ecological conservation in the face of ongoing climatic shifts. This study contributes to the broader understanding of hydrological responses to environmental changes in sensitive mountainous regions.

How to cite: Shi, J., Parajka, J., Zhang, J., Wang, G., and Bao, Z.: Increased Precipitation Yet Decreased Runoff: Unveiling Hydrological Shifts in the Yellow River Source Region Through Permafrost, Snow, and Vegetation Dynamics, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14840, https://doi.org/10.5194/egusphere-egu24-14840, 2024.

A.25
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EGU24-20504
David Williams, Corrine Knapp, Bryan Shuman, Bart Geerts, Melissa Bukovsky, Brent Ewers, Shannon Albeke, Sarah Collins, Jeff Hamerlinck, Martha Inouye, Jewell Lund, Fabian Nippgen, and Ginger Paige

Observation networks established in complex mountain landscapes promise to address critical gaps in understanding of socio-hydrological systems and their process interactions operating at local to regional scales. Knowledge of vulnerabilities and risks founded on observed biophysical and socioeconomic conditions and responses is required to represent realistic scenarios in model simulations of climate change impacts on managed water resources. Socio-hydrological observatories often lack design coordination that consequently constrains the ability to link processes and detect feedbacks across scales and domain boundaries. The goal of the 5-year (2022-2027) project WyACT (Wyoming Anticipating Climate Transitions) is to build adaptive capacity in headwater mountain communities in the Greater Yellowstone Area of of the Rocky Mountains founded on observations, simulation modeling, and driven stakeholder needs and participation. A key feature of WyACT is the development, from the ground up, of a regional observatory network that explicitly coordinates observations of socioeconomic, hydrological, and ecological responses to climate-driven stressors. WY-SEaSON (Wyoming Socio-Environmental Systems Observatory Network) will quantify and monitor the range of responses of snowpack and soil moisture, streamflow, aquatic ecosystems, vegetation stress and fire risk, economic risk perception, and preferred adaptation pathways to a changing climate in a key headwaters region that feeds three major river drainages in western North America. This presentation highlights the structure of WY-SEaSON including the operating principles, goals, mission, and design with examples of emerging and integrated observations.

How to cite: Williams, D., Knapp, C., Shuman, B., Geerts, B., Bukovsky, M., Ewers, B., Albeke, S., Collins, S., Hamerlinck, J., Inouye, M., Lund, J., Nippgen, F., and Paige, G.: Detecting Climate Change Impacts on Socio-Hydrological Systems in the Rocky Mountains, USA, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20504, https://doi.org/10.5194/egusphere-egu24-20504, 2024.

A.26
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EGU24-5178
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ECS
|
Lucas Alcamo, Timo Schaffhauser, Jingshui Huang, and Markus Disse

Water is a strategic and highly contested resource in Central Asia. This is exasperated by a highly uneven distribution of this resource within the region as most of the water originates from the high-mountainous regions. In this study we evaluate the current water resources of the highly mountainous headwaters of the Syr Darya River. Trends in hydrometeorological data are investigated and the dominant hydrological processes are studied using hydrologic modeling. The Syr Darya is one of the two tributaries of the Aral Sea, which has been of high interest due to its drastic decrease. The headwaters investigated in this study include the Naryn and Karadarya Rivers, which originate in the mountainous regions of Kyrgyzstan and flow into the Ferghana Valley where they form the Syr Darya River. The discharge regime is dominated by nivo-glacial processes and therefore highly susceptible to climate change.

Streamflow and climatological data spanning from 1889 until 2018 is statistically analyzed and evaluated with regard to trends and change points. For example, at the gauge in Naryn City, an increase in streamflow can be observed, while precipitation peaks tend to shift to earlier months. The observed temperature increase is above the global average.

For a more comprehensive understanding of the water resources of the region the fully revised version of the Soil Water Assessment Tool (SWAT+) is used to represent the hydrological cycle of the catchments. The model is calibrated using daily streamflow gauges at several locations. In addition, evapotranspiration is calibrated using remotely sensed data from the Global Land Evaporation Amsterdam Model (GLEAM). The model is driven by three different sets of reference data from three ensembles of General & Regional Circulation Models (GCM and RCM, respectively). In detail, we used one RCM, (REMO) and the two sets of GCMs from ISIMIP2 (Inter-Sectoral Impact Model Intercomparison Project) and ISIMIP3. The ISIMIP data is based on the 5th and 6th phase of the Coupled Model Intercomparison Project (CMIP5 and CMIP6), respectively. The different driving climatological data sets are investigated with respect to multiple variables essential for an understanding of the water resources, such as streamflow, evapotranspiration, snow and soil moisture. Besides, observed trends and signals are investigated with respect to their dominant physical controls.

How to cite: Alcamo, L., Schaffhauser, T., Huang, J., and Disse, M.: Water Resources Assessment of the Mountainous Upper Syr Darya Catchment, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5178, https://doi.org/10.5194/egusphere-egu24-5178, 2024.

Hydrological modelling
A.27
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EGU24-16220
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ECS
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Justine Berg, Pascal Horton, Martina Kauzlaric, Alexandra von der Esch, and Bettina Schaefli

The Himalayan Mountain range has a substantial glacier cover, supplying melt water to local communities in the drier season for irrigation and human consumption. Effects of climate change on glacier retreat and therefore melt water availability are expected to be severe. An accurate representation of glacier processes is thus of great importance to predict water availability under future climate projections. Hydrological models focus mostly on processes occurring in non-glacierised areas with often overly simplified glacier parametrization. This can lead to uncertainties in streamflow predictions, especially in highly glacierized catchments. Coupling a glacier model to a hydrological model can resolve some of these uncertainties by a more accurate description of glacier-related processes including ice melt, and providing the extent of glacier retreat, which is essential to quantify changes under a transient climate. In this study, we test the hypothesis that coupling the glacier model GloGEM with the hydrological modelling framework Raven can lead to an increase in predictive skills through a better glacier parametrization. The chosen hydrological modelling framework Raven allows for testing multiple hydrological model structures, accounting for uncertainties along the full modelling chain. The relevance of coupling a glacier model with a hydrological model is analysed in a test basin with in-situ measurements of glacier mass balance and streamflow. Modelling results from coupled and non-coupled model runs are evaluated with the available streamflow data.

How to cite: Berg, J., Horton, P., Kauzlaric, M., von der Esch, A., and Schaefli, B.: Changes in predictive skills through coupling a hydrological modelling framework with a glacier model , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16220, https://doi.org/10.5194/egusphere-egu24-16220, 2024.

Posters virtual: Mon, 15 Apr, 14:00–15:45 | vHall A

Display time: Mon, 15 Apr 08:30–Mon, 15 Apr 18:00
Chairpersons: David Haro Monteagudo, Daniel Viviroli
vA.6
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EGU24-5085
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ECS
Tanja Schäfer, Elke Bozau, and Alexander Hutwalker

Dam reservoirs were used for the continuous water supply to the ore mines in the Upper Harz Mountains. The first reservoirs were built in the 16th century. The dam heights reach up to 15 m and the stored water volumes are between 10,000 and 600,000 m3. There are about 70 of such lakes around Clausthal-Zellerfeld now. Hydrogeochemical data of the lakes have been investigated for about ten years (Bozau et al., 2015). A data management system combining GIS and hydrochemical data is prepared to facilitate data collection and interpretation.

The specific electrical conductivity (SEC) of the lake water ranges between approx. 30 and 280 µS/cm and can be used for the classification of these lakes. SEC lower than 50 µS/cm are typical for lakes mainly filled by rain water. SEC higher than 200 µS/cm are found in lakes near urban and anthropogenic influences. Due to the long dry periods of the last years an increase of the SEC is seen in the majority of lakes especially between spring 2015 and 2023. Because of extraordinary high precipitation in autumn 2023 this trend stagnates or even decreases in some lakes, but is still observable in the comparison between autumn 2015 and autumn 2023.

Especially those lakes with catchment areas strongly changed by forest decline are expected to show higher values of the SEC. In order to investigate this, spatial comparison with forest damage maps is planned. Furthermore, the concentrations of main ions will be investigated in addition to SEC values. Nitrate and potassium concentrations of the lake water should be the most sensitive indicators for forest decline and anthropogenic influences. A first evaluation of organic trace components (Bozau et al., 2022) did not confirm the classification based on the SEC.

 

Bozau, E., Licha, T., Stärk, H.-J., Strauch, G., Voss, I., Wiegand, B. (2015): Hydrogeochemische Studien im Harzer Einzugsgebiet der Innerste. Clausthaler Geowissenschaften, 10, 35-46.

Bozau, E., Licha, T., Warner, W. (2022): Natürliche und anthropogene hydrochemische Parameter der Oberharzer Bergbauteiche. FH-DGGV-Tagung, Jena, März 2022.

How to cite: Schäfer, T., Bozau, E., and Hutwalker, A.: Reservoir lakes in the Upper Harz Mountains (Germany): GIS Implementation and hydrochemical development, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5085, https://doi.org/10.5194/egusphere-egu24-5085, 2024.

vA.7
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EGU24-15204
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ECS
Sagar Gupta, Nikunj K. Mangukiya, Ashutosh Sharma, Sumit Sen, Ankit Agrawal, Domenico De Santis, Christian Massari, and Silvia Barbetta

Understanding natural processes, particularly the water cycle, is inherently challenging due to their unpredictable and complex nature. This complexity is especially pronounced when employing hydrological models, where simplifications introduce various uncertainties. Failing to acknowledge and address these uncertainties can introduce biases into the model outcomes, potentially influencing subsequent decision-making processes. This issue is particularly pertinent in the Indian Himalayan Regions, where significant contributions come from melting of snow and glaciers.  The uncertainties in both model inputs and structures are exacerbated in this region, which is further compounded by the scarcity of reliable data. Consequently, there is a critical need to systematically quantify the diverse sources of uncertainty to ensure accurate and reliable hydrological predictions. This study focuses on the snow-dominant Alaknanda basin within the Indian Himalayan Region (IHR), encompassing three gauging stations. The SWAT+ hydrological model and Modular Assessment of Rainfall-Runoff Models Toolbox (MARRMoT) framework (Trotter et al., 2022) are employed to assess parameter and model structure uncertainties, respectively. The SWAT+ model, calibrated with the Latin Hypercube Sampling (LHS) algorithm, achieved Nash-Sutcliffe Efficiency (NSE) values of 0.56, 0.79, and 0.61. Parameter uncertainty is further examined using diverse parameter sets generated through the LHS algorithm. Furthermore, with the application of 47 lumped conceptual models within MARRMoT framework, assessment of model structure uncertainty underscores the varying importance of processes, particularly snow storage, soil moisture, and routing storage in the study region. The findings reveal that the inclusion of additional storage components in the model leads to a decline in performance, accompanied by an increase in complexity and uncertainties. Notably, the study concludes that, for the investigated region, the contribution of parameter uncertainty surpasses that of model structure uncertainty. These insights emphasize the need for a nuanced understanding of both parameter and structural uncertainties to enhance the reliability of hydrological predictions in data-scarce and complex regions like the IHR.

References:

Trotter, L., Knoben, W. J. M., Fowler, K. J. A., Saft, M., & Peel, M. C. (2022). Modular Assessment of Rainfall–Runoff Models Toolbox (MARRMoT) v2. 1: an object-oriented implementation of 47 established hydrological models for improved speed and readability. Geoscientific Model Development, 15(16), 6359–6369.

 

How to cite: Gupta, S., Mangukiya, N. K., Sharma, A., Sen, S., Agrawal, A., Santis, D. D., Massari, C., and Barbetta, S.: Uncertainties Analysis of the Hydrological Modelling in Himalayan Region: A Case Study of Alaknanda River Basin, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15204, https://doi.org/10.5194/egusphere-egu24-15204, 2024.

vA.8
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EGU24-18725
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ECS
Kavya Mammali, Sanjeev Kumar Jha, and Nicholas Kouwen

Studying the hydrological responses of the Indian Himalayan Region (IHR) is crucial given the rise in the frequency of floods and other natural disasters. The hydrological processes in this area are more complicated due to the extreme weather pattern and varied topography. Streamflow forecasting is made more difficult by the extremely low number of stream gauge stations and the absence of accurate stream flow data. The problem of lack of observational data in ungauged watersheds can be resolved by transferring model parameters from similar gauged basins (Regionalisation). According to the traditional regionalization procedures using rainfall-runoff models, donor and recipient catchments must be similar in a variety of ways, including slope, size, drainage pattern, area, etc. It is extremely difficult to locate a catchment with all those similarities. In this study, we use a fully distributed hydrological model WATFLOOD for developing a streamflow forecast of the Alakananda River basin where the stream flow observation is very limited for the calibration of the hydrological model. WATFLOOD is working based on Grouped Response Unit (GRU). The requirement that has to be satisfied for regionalization using the WATFLOOD model is that land cover classes of the ungauged watershed should be represented in the gauged watershed irrespective of their spatial distribution. Also, there should be as many as possible gauged sub-watersheds that represent each land cover class. We identified a similar watershed that has similar land cover classes and sufficient stream flow gauges to represent each of the land cover classes. The three-step calibration process of the WATFLOOD model for both river basins is carried out to transfer the parameters. The results of ongoing work will be presented at the conference.

How to cite: Mammali, K., Jha, S. K., and Kouwen, N.: Towards developing a streamflow forecasting system for data-poor mountainous watershed: an approach using parameter transfer, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18725, https://doi.org/10.5194/egusphere-egu24-18725, 2024.