There is a high level of confidence and scientific consensus that climate change is the primary driver of the melting and thawing of the cryosphere and that the cryosphere changes are happening at unprecedented rates. While the bulk of literature in this space is about physical changes in the cryosphere, increasingly, a body of literature has evolved that also recognizes the contribution of the cryosphere to human societies, particularly that of high mountain communities. On the lines of the ecosystem services framework, the cryosphere services framework has been used to classify the different goods and services that the cryosphere provides to human societies. These services include supply services (irrigation, water supply, etc.), socio-cultural services (sports, tourism, spiritual, etc.), regulation (regulating climate and water systems), and habitat services. While the cryosphere provides a whole range of goods and services for mountain communities, as mentioned above, not all of these are well documented. Significantly, how these services are being impacted due to the melting and thawing of the cryosphere is poorly understood. Even within the services, some, like material services (e.g., supply of water for irrigation and agriculture), and disservices such as disasters, are better documented than non-material services like the spirituality of landscapes. A part of the reason lesser attention is given to human aspects of the cryosphere change is the lack of inter-disciplinary perspectives in cryosphere studies, as well as the use of critical epistemologies from social sciences which can be used to examine how politics, power, and intersectionality influence societal responses to changes in the cryosphere. I will use this session to argue for enhanced interdisciplinary collaborations to understand human impacts and adaptive responses to cryosphere change.
How to cite: Mukherji, A.: Interdisciplinary perspectives are needed to understand the human impacts of cryosphere change, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-19613, https://doi.org/10.5194/egusphere-egu25-19613, 2025.
Water is the foundation of healthy communities, ecosystems, and economies. Clean, reliable water is critical for drinking, producing water-intensive commodities, thermoelectric power generation, and maintaining healthy ecosystems and economies. Rural areas disproportionately provision natural resources such as freshwater to downstream cities, which are primary locations of economic productivity, prosperity, and populations. Increasing and unprecedented pressure on water resources from climate change, population growth, water use, land cover, and pollution, creates a critical need to understand the dependency of downstream economies on upstream locations that provision freshwater supplies. Previous studies have substantiated upstream-downstream dependencies at continental- and country scales, which are too spatially coarse for meaningful basin-scale decision-making. This research presents a spatially explicit basin-scale water tower model (initially developed by Viviroli et al., 2007) that quantifies upstream-downstream dependence by spatially connecting downstream water users (e.g., public water supply) to upstream locations of runoff generation in addition to comparing the impact of different spatial resolution hydrologic datasets. We focus on the Potomac River watershed in the Mid-Atlantic Region of the United States of America, which provides ~75% of surface water supplies in the Washington, D.C. metropolitan area. Recent research suggests near-term scenarios with water scarcity throughout the watershed due to population growth, increased water demand, and increased aridity due to climate-driven increases in atmospheric demand. This basin-scale, gridded water tower model identifies spatially explicit locations and land cover within the watershed that disproportionately largely supply fresh water to the Washington, D.C. metropolitan area, underscoring its reliance on rural hinterlands. Our findings provide insights for basin-scale integrated water resource management planning by highlighting the potential impacts of land use changes and climate change on these critical water generation areas. We highlight the importance of decision-ready science in water resource management, particularly in domains such as water allocation, infrastructure planning, and ecosystem restoration. By leveraging geospatial data science and comparing high-resolution hydrologic datasets, this research provides actionable insights to guide decision-makers in developing strategies that ensure the long-term sustainability of water resources.
How to cite: Sjöstedt, E., Kearns, M., Rushforth, R., and Zegre, N.: Linking Downstream Water Use with Upstream Water Production - Insight from a High-Resolution Water Tower Model of the Potomac River Watershed, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-12099, https://doi.org/10.5194/egusphere-egu25-12099, 2025.
The Alps have been recognised as hotspot areas for European climate change impacts. The ongoing and future changes in air temperature and precipitation impact the hydrological cycle not only for what concerns snowmelt and rainwater magnitude and timing but also for evapotranspiration fluxes. Evapotranspiration (ET) plays a major role in the water balance of alpine catchments as it pumps back to the atmosphere 60-80% of the precipitation and regulates precipitation recycling. Its importance is not limited to the alpine region but goes far beyond the Alps influencing the atmospheric moisture transport and impacting the water availability in downwind areas.
The recycling and downstream effects of changes in ET are not only hydrological but extend to economic and socio-political dimensions, particularly when countries rely on precipitation originating in foreign countries. Understanding these dynamics is crucial to addressing challenges in water resource management, land use, agriculture sustainability, and energy production.
While hydrological effects due to the decreases in snow and glacier cover over the Alps have been widely studied both at catchment and regional scales, studies on the downwind effects of the variations in ET at regional and continental scales are still few. This study addresses this knowledge gap by assessing both the geographical region of origin of the water that precipitates on the Alps and the areas where the evapotranspiration water from the Alps precipitates (constituting the so-called green water for these are., In doing this, we pay particular attention to precipitation recycling processes and the green water corresponding to agricultural lands, highlighting water vapor-mediated links between alpine and agricultural areas.
To effectively evaluate the destination of evapo-transpired water we employed the water vapor tracking model UTrack over the 2008-2017 mean year. Due to the spatial variability and the critical role of local factors in shaping ET within the alpine environment, we coupled UTrack with the high-resolution ERA5-Land dataset. This approach provides insights into the relationship between alpine water cycles and downstream hydrological dependencies.
How to cite: Chiesa Turiano, N., Tuninetti, M., Laio, F., and Ridolfi, L.: Hydroclimatic role of the Alps as sinks and sources of moisture, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-3737, https://doi.org/10.5194/egusphere-egu25-3737, 2025.
Mountains are important water sources, storing water, releasing it in a buffered fashion and distributing it to the low-lying forelands. At the same time climate change is most pronounced in mountain regions, putting pressure on the water resources there. Understanding these changes requires better monitoring to robustly predict the changes in the mountain water cycle. In particular crucial is the seasonal supply of water by precipitation and the links with the evaporative source region, which again might depend on local changes there. To trace these pathways, automated water sampling devices are essential. To do so, we have developed an automated rain water sampler, that is robust to work under harsh conditions, can take 165 samples every 5min, is remotely accessible and provides samples of high analytical quality without atmospheric exchange.
From May to August 2022, we deployed 6 samplers across one of the most pronounced orographic precipitation gradients, the Himalayas in Nepal. The samplers were installed along the Kaligandaki River corridor, from ~ 100 m to 3700 m asl., from the border with India in the south to the dry region north of the mountain range. The sampling period was chosen to cover the sharp transition of the two contrasting seasons, pre-monsoon and monsoon. All samplers operated simultaneously for the full time with little technical downtime and we collected six unique high-resolution rainfall stable water isotope timeseries with roughly 1000 new samples. All measurements plot on the first order along the global meteoric water line. Temporally, the results show for all 6 stations a market trend with positive isotopic signatures during pre-monsoon and a very quick transition to negative signatures with the onset of monsoon. The pre-monsoon isotopic signatures are all in the range +30 to +40‰ in δ2H and all 6 stations at all elevations follow the same variability. Monsoon samples are in the range between -50 to -150‰ in δ2H. Unlike during pre-monsoon we observe a market separation of the isotopic signatures according to the elevation of the station. The lower station in the Gangetic Plains depicts signatures of around -50‰ δ2H, while the highest station features the lowest signatures of -150‰ δ2H. We attribute this market changes to the source signature of the evaporative source region. The pre-monsoon shows clear continental recycling signature and is sourced during the hot and moist pre-monsoon season from the Gangetic Foreland, Vapor during this season is transported in erratic and well mixed storm events toward the mountains. While the monsoon moisture is sourced far offshore in the Indian Ocean. The change between the two systems is very clear depicted in the isotopic signature. We accompany these analyses by lagrangian back trajectory analysis to determine the sources regions.
These findings show how variable the seasonal isotope input signatures in the Himalayan hydrological system are which has important consequences for tracing endmember signatures as well as the interpretation of climatological archives such as tree-rings or ice-cores and predicting future changes in the Himalayan water cycle with respect to the evaporative source regions.
How to cite: Andermann, C., Sachse, D., Sodemann, H., Adhikari, B. R., Gajurel, A., Queißer, T., Reich, M., Teagai, K., Brunello, C., and Hovius, N.: Arrival of monsoon, rainfall isotopic determination of the pre-monsoon - monsoon transition, tracing moisture sources across the Himalayas, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-17559, https://doi.org/10.5194/egusphere-egu25-17559, 2025.
Mountains cover approximately one-quarter of the Earth's land surface, with a significant proportion of the global population residing in their vicinity. Orography plays a pivotal role in shaping weather processes across multiple spatial and temporal scales. When combined with factors such as land-cover heterogeneity and mesoscale atmospheric processes, it generates substantial spatial variability in mountain weather, as exemplified by the Tropical Andes. This study focuses on the diurnal dynamics of convective cloud entities, particularly small-scale cells associated with moderate convective rainfall, over the eastern slopes of the Tropical Andes. The analysis is based on high-resolution observations from a scanning X-band rain radar and numerical simulations performed using the WRF model. The results reveal that the formation of convective clouds in the lowland regions of the study area is modulated by varying advection velocities. A nocturnal enhancement in the formation of convective cells was observed, with advection velocities around 10 m/s. In contrast, during the period between 12:00 and 16:00, these cells exhibited rapid advection, with velocities reaching approximately 20 m/s. We will present the thermodynamic mechanisms driving the cloud formation, as well as the link with mesoscale convective systems.
How to cite: Urdiales Flores, D., Koukoula, M., Jan de Vries, A., Araya, J., Dominguez, F., Célleri, R., and Peleg, N.: Exploring the formation of convective clouds in the Tropical Eastern Andes, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-13473, https://doi.org/10.5194/egusphere-egu25-13473, 2025.
The Alps serve as Europe's water tower, making perialpine regions heavily dependent on their water balance and susceptible to climate and management induced changes in water availability. In recent decades, the Alps have experienced an increasing number of droughts, leading to severe impacts on hydropower production, drinking and irrigation water allocation, ecosystem health, and tourism. These trends necessitate a comprehensive understanding of future drought patterns in the region.
To evaluate and analyze alpine droughts, regional climate model data from a single-model large ensemble comprising 50 members from 1990 to 2099 is used. The ensemble approach enables both future projections and the quantification of natural climate system variability, thereby enhancing the robustness of the results. This is particularly crucial when analyzing extreme events such as droughts, as it increases confidence in the observed signals while reducing uncertainty in the projections.
Given the heterogeneous landscape and climatic conditions of the study area, our methodology needs high-resolution spatial data specifically optimized for the considered terrain. The approach combines advanced downscaling techniques with a terrain-specific bias-correction method to generate reliable estimates of precipitation patterns and other critical climate parameters.
The resulting dataset is designed to serve diverse research needs, from hydrological studies to engineering applications and tourism geography. These high-resolution climate projections provide a broad range of hydroclimatic services and will contribute to the development of drought early warning and prediction systems, the implementation of optimized cross-sectoral drought risk management strategies and the enhancement of regional adaptation capabilities to drought conditions.
This comprehensive approach bridges the gap between climate modeling and practical applications, providing stakeholders with robust scientific foundations for decision-making in drought management and adaptation planning.
The presented study is conducted in the frame of the A-DROP project, funded through the INTERREG Alpine Space Programme.
How to cite: Pentenrieder, M., Ludwig, R., and Castelli, M.: Modeling Alpine Droughts: Bias-Correction and Downscaling of a Climatic Single-Model Large Ensemble, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-15863, https://doi.org/10.5194/egusphere-egu25-15863, 2025.
In recent years, Alpine regions have experienced several winters with little snow. This lack of snow - also referred to as snow drought - can have serious hydrological consequences, as highlighted by the prolonged hydrological drought in northern Italy in 2022. This event illustrates the important link between a snow drought in the upper reaches and a hydrological drought in the lower reaches of the catchment. Snow storage is expected to decrease in response to rising temperatures, which may lead to a potential increase in the number and spatial extent of snow droughts . However, it is not yet clear whether a decline in snow storage and the occurrence of low-snow years are solely caused by rising temperatures or whether changes in other, dynamic mechanisms, such as weather patterns leading to persistent dry spells, also play an important role.
Here, we use two national daily gridded snow products for Switzerland and Austria to quantify (1) changes in catchment snow storage, i.e. snow water equivalent (SWE), since 1961and attributing these changes to SWE deficit contributions from low to high elevation bands; (2) changes in seasonal accumulation and melt characteristics; and (3) the occurrence, dynamics, and meteorologic drivers of low-snow years, i.e. years with annual maximum SWE below the 30th percentile, across various elevation bands.
Our results show a median loss of total annual catchment snow storage of approx. 20 % across 251 catchments in Switzerland and Austria over the period 1962-2023 , with a marked regime shift at the end of the 1980s. All elevation ranges experience a loss in snow storage, but most of the snow loss (approx. 60%) can be attributed to the loss in middle elevation snow storage (1200-2100m). Further, we observe a clear increase in the fraction of area under low snow conditions in all elevation bands, especially since the late 1980s. Thereby, low snow years are connected to below normal winter precipitation, especially at higher elevations (>2100m). At lower and middle elevations, warm winter temperature anomalies are additionally important to explain the occurrence of low snow years. A better understanding of the observed trends and the dynamical drivers of low snow years will help us to better constrain future projections of snow storage and associated hydrological impacts.
How to cite: Wood, R. R. and Brunner, M. I.: Loss in snow storage: attribution to elevation bands and meteorological drivers in the Alps, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-16243, https://doi.org/10.5194/egusphere-egu25-16243, 2025.
The livelihoods of millions of people worldwide depend on meltwater from glacierized catchments, which are critical resources for drinking water, agriculture, and power production. However, climate warming profoundly affects the water storage and transfer functions of these catchments, posing significant challenges to water resource management in mountain regions. In alignment with the United Nations’ designation of 2025 as the International Year of Glacier Protection and the pursuit of Sustainable Development Goal 6 (Clean Water and Sanitation), there is an urgent need to understand and address these changes and develop adaptive strategies.
The relative contributions of glacier melt, snow melt, precipitation, groundwater, and other sources to streamflow remain poorly understood in many glacierized regions. This knowledge gap complicates efforts to predict and manage water resources amid expected climatic changes. Isotope-based methodologies provide a powerful tool to quantify these contributions, offering valuable insights into the current and future status of water resources in glacierized catchments.
As part of the coordinated research project initiative titled “Understanding Hydrological Processes in Glacierized Catchments under Changing Climate using Isotope-Based Methodologies (F33031)” by the International Atomic Energy Agency (IAEA), a key objective is to develop a comprehensive database of isotopic signatures for the various endmembers contributing to streamflow. These endmembers, which vary depending on the specific catchment, include for example glacier melt, snowmelt, precipitation, groundwater and outflow from rock-glaciers and ice-cored moraines.
This research aims to establish a global reference framework to support the development and application of isotope-based methodologies, enabling a standardized approach to understanding flow paths and their contributions to streamflow. By elucidating these dynamics, the framework will help assess how contributions evolve with seasonal and inter-annual climatic variations. These insights are essential for accurately evaluating changes in total discharge volumes and implementing sustainable water management strategies to address the impact of climate change on mountain hydrology.
How to cite: Sapper, S. E., Vital, M., Dàvila Roller, L., Fernandoy, F., Gorritty, M., Jeonghoon, L., Masse-Dufresne, J., Nishonov, B., Persoiu, A., Saidaliyeva, Z., Shahgedanova, M., Tao, P., Temovski, M., Vreča, P., Wade, J. A., and Vystavna, Y.: Advancing isotope-based understanding of water resources in glacierized catchments to adapt to a changing climate, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-15431, https://doi.org/10.5194/egusphere-egu25-15431, 2025.
Mountain meltwater sustains a sixth of the global population. However, water security in mountainous regions, along with the livelihoods of millions of people, is now under threat due to a warming climate causing a reduction of snow input and increased ice ablation in these environments.
Mountain water resources are often mapped via the modelling of snowfall, snowpack, glacier mass balance and runoff in the mountain cryosphere. Model skill is, however, fundamentally limited by the quality and availability of key observational data which are too sparse, inaccurate and infrequent to constrain models adequately. As a result, mountain water resources are systematically underestimated by 50-100% in all of the world’s major mountain ranges.
In order to address these challenges, we aim to fill gaps in observations in precipitation, glacial thickness and meltwater runoff to test and improve skill in water resources modelling in the Alps, Austria and the Himalayas, India. Using new observations, the innovative modelling approach couples a glacier model, a snowmelt model and a hydrological model for an improved representation of mountain water resources both now and in the future. The use of isotopic tracers will be used to further help parameterise the model and identify biases in the modelled water resources, helping to provide a more robust approach to the prediction of water resources up to the end of the 21st century under climate change scenarios.
How to cite: Rickards, N., Baron, H., and Reynolds, A.: An innovative modelling approach for the quantification of mountain water resources , EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-19201, https://doi.org/10.5194/egusphere-egu25-19201, 2025.
The unique topographical and climatic conditions of the Himalayan region along with fewer hydrometeorological stations, add complexity to the hydrological modeling of this region. This study addresses the constraints of calibrating a hydrological model in a data-scarce watershed by substituting reanalysis surface runoff data (RSRD) for discharge data. In this study, we calibrated a distributed hydrological model, WATFLOOD, using ERA-5 surface runoff data. We assess water balance components in nine land use classifications across different locations in the study area. We also evaluate six separate water balance components over time using simulated data from different land use classes. Our results indicate that the WATFLOOD model can successfully replicate the water balance in the Himalayan region (CC = 0.8 and NSE = 0.75). Since the observation data is not easily accessible, RSRD can be utilized to calibrate the hydrological model. We validated our results with observed data available at one station for a short period. Our results reveal the drawbacks of calibrating a hydrological model with RSRD. The annual fluctuation of water balance components above and below ground in each land cover class varies in response to wet and dry years. The less variation of Total Upper Zone Storage (TUZS) and Lower Zone Storage (LZS) in dry and wet years shows that these water balance components are independent of the rainfall in the region. The proposed hydrological model has the potential to help manage water resources in highland locations with limited data.
Keywords: WATFLOOD model, Reanalysis Surface Runoff, Alaknanda River basin, Western Himalayan region
How to cite: Mammali, K. and Kumar Jha, S.: Calibration of a physically based distributed hydrological model: a case study of the Alaknanda River basin, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-18454, https://doi.org/10.5194/egusphere-egu25-18454, 2025.
Tropical montane catchments play a critical role in regional hydrological processes. However, rainfall-runoff dynamics and their change across spatial scales remain understudied. Understanding these processes is essential for water resource management in the face of climate change and human activities. To address this knowledge gap, we conducted a multi-scale study of six sub-catchments in a lake-dominated tropical Andean system (~3200 – 4400 m a.s.l.), ranging from 6.19 km² to 90.7 km² over 10 years. We applied a multi-criteria approach including hydrometric data analysis, simple mixing models (MM) to determine geographical sources of streamflow contributions, mean transit time (MTT) estimations, and regression analyses to identify the key drivers of catchment behavior. Our results showed that runoff coefficients exhibited higher values on the headwater catchments suggesting that lakes regulate discharge primarily at small scales. Mixing model results showed that streamflow contributions stemmed from rainfall, wetland soil water, and groundwater from varying depths, with smaller catchments heavily influenced by wetlands and larger ones relying on groundwater recharge. Notably, groundwater contributions were higher below 3442 m a.s.l. suggesting a significant discharge area at this elevation. Discharge MTTs ranged from a few weeks in the smallest catchments to more than one hundred weeks in the largest, while groundwater MTTs extended from one hundred up to two hundred weeks, reflecting contributions from deeper zones. Regression analyses revealed that mean catchment slope, among other factors, significantly influenced hydrological behavior. This study demonstrates the value of a multimethod, multiscale approach for understanding rainfall-runoff dynamics in tropical montane systems. Our findings emphasize the regulatory role of headwater lakes at small scales and the previously underestimated role of deep groundwater contributions in larger catchments, providing a foundation for improved hydrological modeling and sustainable water management strategies in the tropical Andes.
How to cite: Ramón, J., Crespo, P., and Timbe, E.: Unveiling Rainfall-Runoff Dynamics Across Spatial Scales: Insights from a Tropical Montane Andean Catchment, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-567, https://doi.org/10.5194/egusphere-egu25-567, 2025.
The food and water security of 90 million people depends on the Andean Mountain water tower, which is at risk in several regions because climate change is altering water storage in high altitude wetlands (bofedales), lakes, snow and glacier ice. These features play a crucial role in delaying water release, particularly in many semiarid regions with pronounced seasonal drought, sustaining baseflows and water quality. Changing water availability impacts both high Andean pastoralist systems and other productive systems downstream, including bigger cities in the inter-Andean valleys. Here we outline the hydrological and geomorphological relationships between glaciers, lakes and wetlands, and the way in which catchment features such as moraines, talus slopes and sandar interact with catchment hydrology in the tropical Andes of Peru. We present a geomorphological map of catchment features in the Cordillera Vilcanota, Cusco region, Peru, and explore how these features can impact hydrogeological processes. We explore the ways in which well mapped and dated catchment features can give a damming or groundwater/surface water exchange mechanism for bofedal development. Such analysis enables an improved understanding of the timeframe for the formation of wetlands and for them to provide their key ecosystem services of water retention capacity, buffering drought, providing forage for alpaca and herding, and carbon storing and sequestration.
How to cite: Davies, B., Gribbin, T., King, O., Matthews, T., Baiker, J., Becker, R., Buytaert, W., Carrivick, J., Drenkhan, F., Garcia, J.-L., Montoya, N., Perry, B., and Ely, J.: Landsystems of the tropical high Peruvian Andes: glaciers, lakes, wetlands and water resources in the Cordillera Vilcanota , EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-5766, https://doi.org/10.5194/egusphere-egu25-5766, 2025.
In the southwestern United States, the Upper Colorado River Basin (UCRB) faces substantial water availability challenges. Snowmelt dominates hydrology in the basin, with much of the streamflow originating as meltwater. Snowmelt either becomes surface runoff or groundwater recharge, but this partitioning is not well constrained. Furthermore, groundwater recharge from snowmelt can discharge back into streams becoming an important component of streamflow. On average, over half of the streamflow in the UCRB is estimated to originate from groundwater discharge to streams, highlighting the importance of baseflow in sustaining surface water. Yet we have not quantified past spatio-temporal variability of baseflow and its contributions to streamflow, nor do we understand variations in streamflow and baseflow sources under shifting hydroclimates. Here we describe the development and application of linked models of baseflow and streamflow to characterize sources and transport pathways of both baseflow and streamflow in the UCRB at a seasonal timestep from 1986-2020, including the lagged delivery of groundwater to streams over longer timescales. Results suggest that baseflow yields are greatest in headwater catchments during spring, and that a majority of baseflow is derived from water that takes over one season to move through the subsurface to streams. We also find that although streamflow and its sources vary seasonally, on average across the basin, about half of streamflow is from baseflow, which is particularly important for sustaining streams outside the snowmelt season and at lower elevations.
How to cite: Miller, O., Miller, M., Longley, P., McDonnell, M., Wise, D., and Schmadel, N.: Quantifying seasonal snow and groundwater contributions to streamflow across the Upper Colorado River Basin, 1986-2020, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-1541, https://doi.org/10.5194/egusphere-egu25-1541, 2025.
Groundwater springs are essential water sources in hilly and mountainous regions. India’s springs are facing water scarcity due to groundwater overuse with increasing population growth and climate change. This study explores groundwater springs in Assam's Dima Hasao district, focusing on spring emergence, spring water chemistry, suitability for drinking and irrigation, and potential groundwater recharge zones, where these parameters are not well documented. Inventory parameters include GPS coordinates, rock type, slope measurement of the catchment, spring type, nature of discharge, and surrounding land use land cover. Instruments used for field observations were a GPS device GARMIN etrex10, a bucket of a specific volume, a stopwatch, and an on-site water testing kit-Hanna instrument. The springs found mainly emerge from fracture zones, joint planes, and contact zones between residual soil and bedrock with varying elevations, classified as fracture and depression springs. All springs that were evaluated at 52 sites are non-thermal springs. Discharge rates ranged from 0 to 12 liter/minute. As per Meinzer's classification, springs are ranked as sixth, seventh, and eighth magnitude. For chemical analysis, the concentration parameters were determined using a flame photometer, spectrophotometer, and volumetric titration methods as required for different parameters. Precipitation is found as the primary factor controlling the water chemistry. Water types identified included Ca-Mg-Cl-SO4, mixed Ca-Mg-Cl, and Ca-Mg-HCO3, indicating mixed temporary and permanent hardness. Stable isotope analysis of hydrogen and oxygen using Liquid-Triple Isotopic Water Analyzer (L-TIWA) revealed that recycled moisture contributed to the local precipitation with a few secondary evaporative effects. Water Quality Indices based on chemical parameters showed that 24% of samples needed treatment before consumption. Significant faecal contamination was noted which was determined from the microbial analysis i.e., most probable number determination. Adequate treatment of spring water is essential because of the microbial contamination. All springs are suitable for irrigation as per irrigation indices. Groundwater Potential Zones (GPZs) were created by integrating six layers using AHP and GIS techniques, classified from very poor to very high potential. The occurrence of springs in the area is compared with the GPZs and results have shown that sixth, seventh, and eighth-magnitude springs were located in predicted very high, high, moderate, and poor potential zone areas. The findings from this study were crucial for springshed management. Considering seasonal variations in spring water discharge and quality, mapping groundwater and groundwater springs potential zones, and constructing artificial recharge structures can contribute to effective water management in the hills of Dima Hasao and similar regions facing climate impacts. The study highlights the importance of regularly monitoring spring resources in Assam hills, artificial recharge to maintain spring discharge amidst climate change, and aiding policymakers in crafting sustainable management plans to meet the UN’s sustainable development goals XIII (climate change action).
Keywords: Spring, groundwater, groundwater potential, springshed management, water quality indices
How to cite: Gogoi, M. and Choudhury, R.: Inventory of Groundwater Springs in the Hills of Assam, India: An Approach to Springshed Development, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-1104, https://doi.org/10.5194/egusphere-egu25-1104, 2025.
The trans-boundary Indus River basin aquifers span 16 million hectors across six countries. Although extensive research on groundwater quality and quantity has been conducted in its middle and lower reaches, the high-altitude aquifers have gone unnoticed until recently. The goal of the submitted work is to understand the groundwater – aquifer matrix reactions responsible for observed water chemistry, through geochemical mass – balancing and 87Sr/86Sr isotopic systematics. Located at average altitude of 3500 m these shallows of the Indus Basin are devoid of any significant anthropogenic interferences, and provide a unique opportunity to study the processes of water – rock interaction.
Mildly reducing to oxidizing Ca – HCO3, Ca – Mg – HCO3 waters were collected from a variety bedrock (from ultrabasic to acidic and from carbonate to siliciclastic) and over-burden aquifers (fluvial, fluvio – glacial, aeolian, lacustrine). Sodium normalised mixing diagrams suggest a dual pathway of carbonate and silicate weathering. Thermodynamic calculations show waters are nearly saturated in calcite, oversaturated in Fe oxy(hydr)oxides, and in equilibrium with kaolinite. Groundwater Sr varies from 57 to 3416 μg/L and 87Sr/86Sr ratios from 0.7075 to 0.7275. Groundwater Sr/Ca and 87Sr/86Sr ratios are significantly higher than those of typical carbonates, suggesting a dominance of silicate weathering. Scattering in Sr–solute relationships, lack of a linear trend between 1/Sr and 87Sr/86Sr and correlations of 87Sr/86Sr with other solutes and indicators of silicate weathering (SiO2/TDS, Na + K/total cationic charge) points towards derivation of solutes from multiple silicate sources. Mass – balancing suggests, a variety of silicate minerals (serpentine, olivine, chlorite, pyroxene, and biotite, plagioclase and alkali feldspars) have weathered to kaolinite, vermiculite and illite. Groundwater 87Sr/86Sr ratios in granitoid, siliciclastic, and ophiolitic aquifers matches well with their aquifer matrix values establishing them as their solute sources. Strong mismatch between aqueous and solid phase 87Sr/86Sr signatures in basaltic aquifers suggests solutes in them is derived from more radiogenic Himalayan sources.
How to cite: Coomar, P., Lone, S., Jeelani, G., Upadhyay, D., Gupta, S., and Mukherjee, A.: Lithological control on groundwater chemistry in the Trans-Himalayan Indus River basin aquifers, India, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-17501, https://doi.org/10.5194/egusphere-egu25-17501, 2025.
Mountains are vital freshwater sources for nearly half of the global population but face increasing threats from climate change and human pressure. Understanding the impacts of these changes in mountain catchments is essential for developing effective mitigation strategies and conserving their unique ecosystems. Our study investigates the effect of climatic changes and large-scale teleconnection patterns (Arctic Oscillation, North Atlantic Oscillation) on streamflow dynamics in headwater mountain catchments under varying degrees of human pressure. The study is based on time series analysis of streamflow records, meteorological data, and teleconnection indices from 1971 to 2020, and employs trend analysis, wavelet analysis, and paired catchment observations.
Our findings reveal a significant increase in air temperature in the region (+0.4°C decade-1) over the past 5 decades. While total precipitation remained stable, annual snowfall totals declined by 69 mm decade-1. Air temperature and precipitation changes varied with altitude and season: temperature changes were more pronounced in summer at lower altitudes, while precipitation shifts were most evident in winter at higher altitudes.
Snow depths remained relatively unchanged, but snow cover duration decreased by up to 4 days per decade. These climatic shifts resulted in a notable increase in annual low flows (up to 11.5% per decade), as well as winter low, average, and high flows. The impact of teleconnection patterns on streamflow varied over time and was more pronounced at longer time scales (≥1 year).
Streamflow changes were more pronounced in semi-natural catchments compared to human-altered catchments. Climatic-driven streamflow trends were most evident in winter, while land use changes (windthrow) and human activities drove year-round trends. Precipitation and discharge exhibited stronger coherence across all time scales in human-altered catchments, suggesting greater susceptibility of these catchments to precipitation extremes. The amplification of the annual precipitation cycle and semi-annual snow cover cycle at higher altitudes, coupled with the intensification of the semi-annual streamflow cycle, underscores the impact of ongoing climatic changes. The observed streamflow variability reflects the intricate interplay of climate change, large-scale atmospheric oscillations, extreme events, and human activities.
How to cite: Rajwa-Kuligiewicz, A. and Bojarczuk, A.: Streamflow variability in the Tatra Mountains, Western Carpathians: Combined effects of climate change, teleconnection patterns, extreme events, and human pressure, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-12025, https://doi.org/10.5194/egusphere-egu25-12025, 2025.
The cryosphere in mountain areas serves as a critical water resource, supplying melt water to downstream communities in spring as well as summer months for irrigation and human consumption. Effects of climate warming on the cryosphere and therefore melt water availability are expected to be substantial for many mountain ranges worldwide. An accurate representation of glacier processes is thus crucial to predict future water availability in catchments that are currently at least partially glacier-covered. Hydrological models often focus on meltwater-streamflow transformation processes occurring in non-glacierized areas with sometimes an overly simplified representation of glacier dynamics and melt. This can lead to uncertainties in streamflow predictions, especially in highly glacierized catchments and for longer time horizons. Coupling a glacier model with a hydrological model can address some of these uncertainties by a more accurate representation of glacier-related processes including ice melt and changes in glacier extent, which are essential to quantify streamflow changes under a transient climate. This study couples the global glacier model GloGEM with the semi-distributed hydrological modelling framework Raven to enhance the representation of these glacier dynamics. The implemented one-way coupling (from the glacier model to the streamflow model) aims to reduce uncertainties and improve predictions of streamflow and water availability under transient climate conditions. The relevance of using a global-scale glacier model for local-scale hydrological modelling is evaluated in 15 glaciated catchments in Switzerland. Initial results indicate that the coupled model enhances streamflow predictions and provides a more accurate representation of glacier melt contributions to streamflow. These improvements influence model parameters, particularly snow-related ones, which previously compensated for deficiencies in the modelled glacier melt, thereby leading to changes in snowmelt contributions to streamflow. This study assesses how these shifts in glacier and snowmelt contributions under future climate scenarios impact water availability.
How to cite: Berg, J., Horton, P., Kauzlaric, M., von der Esch, A., and Schaefli, B.: Integrating a Global Glacier Model into Local Hydrological Modelling: Impacts on Future Water Availability, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-8857, https://doi.org/10.5194/egusphere-egu25-8857, 2025.
Western Patagonia's vast freshwater ecosystem, where glacial and non-glacial waters converge, is increasingly threatened by climate change, disrupting runoff patterns and endangering water resources. Here, we present estimates of past and future glacio-hydrological changes for 2,236 catchments in Western Patagonia, projecting impacts through the 21st century under contrasting climate change scenarios. Leveraging recent advances in the development of regional and global datasets, we applied a hybrid approach combining Long Short-Term Memory (LSTM) neural networks with process-based glacier modelling (Open Global Glacier Model). We evaluated the approach’s ability to predict streamflow in ungauged basins (PUB) and regions (PUR) through 10-fold cross-validation, and compared the results with those from a pure LSTM model and two process-based hydrological models. Additionally, we assessed how the different model predictions extrapolate spatially and project over time. The results show that the hybrid modelling approach outperformed all conventional approaches in more than 70% of the catchments considering PUB and PUR evaluations. Using this approach, we estimated a regional discharge of nearly 20,000 m³ s⁻¹ (2000-2019), with an average glacial contribution of 20%. By the end of the century, we project marked shifts in river seasonality under climate change scenarios. Under a high emissions scenario, the northern region (>46°S) is projected to experience the largest reductions in runoff, with dry season runoff decreasing by almost 50%. In contrast, glacierised basins in the southern regions are projected to show slight increases, with average relative changes of 20%. The results highlight the potential of hybrid modelling to provide new information for climate change adaptation in Western Patagonia.
How to cite: Aguayo, R., Zekollari, H., Hanus, S., Baez-Villanueva, O. M., Mendoza, P., and Maussion, F.: Divergent spatial runoff trends in Western Patagonia projected by hybrid glacio-hydrological modelling, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-12458, https://doi.org/10.5194/egusphere-egu25-12458, 2025.
The development of flood adaptation and mitigation strategies to climatic changes requires frameworks to predict potential future design floods (e.g. the 1% Annual Exceedance Probability (AEP)) and their associated uncertainty. We present a modelling framework that predicts potential future flood hazards from probabilistic climate scenarios. The framework assesses the drivers of change and the predictive uncertainty and is implemented for the Central Himalayan Karnali River.
The modelling framework applies a continuous hydrological model within a Generalised Likelihood Uncertainty Estimation (GLUE) with climate projections of the latest generation of climate models (12 CMIP6 models). We then conduct a Flood Frequency Analysis (FFA) to estimate the probabilities of extreme flows and use a bootstrapping approach to estimate the uncertainty related to the internal variability.
We project an intensification of flood hazards with time and emissions. The 1% AEP flood magnitude is projected to increase by 23% (medium-emission scenario SSP245) and 26% (high-emission scenario SSP585) in the near-future (2020 – 2059), and by 40% (SSP245) and 79% (SSP585) in the far-future (2060 – 2099) compared to the baseline period (1975 – 2014). Consequently, the flood magnitude of the baseline 1% AEP event is projected to occur once every 11 years (SSP245) and 3 years (SSP585) in the far-future. This intensification is to >90% driven by rainfall-runoff increases and is, thus, attributed to changes in the precipitation characteristics. The baseflow and glacier melt contributions remain similar while snowmelt contributions decrease due to an earlier onset of the melting season.
We analyse the standard deviation (SD) to assess the uncertainty contribution of the modelling components. The hydrological model is a main source of uncertainty, but its contribution is independent of time, emissions and event frequency (SD: 21 – 24%). The uncertainty related to the climate projections increases with time and emissions from 14 – 18% in the baseline period to 22 – 28% (SSP245) and 29 – 32% (SSP585) in the far-future. The uncertainty introduced by the FFA is generally independent of time and emissions and increases with the event frequency from 8-9% for the 10% AEP event to 11 – 16% for the 1% AEP event. However, we detect that the uncertainty increases with the increasing flow difference between the rarest and more frequent events and is, thus, sensitive towards the projected precipitation extremes.
We conclude that flood hazards intensify with GHG emissions in the Central Himalayan River system because of changes in the monsoon precipitation characteristics. The projections of potential future hazards to guide flood adaptation and mitigation strategies need to consider the uncertainty in the climate projections, the internal variability, and the hydrological simulations.
How to cite: Pink, I., Reaney, S., Bovolo, I., and Hardy, R.: Increased rainfall-runoff drives flood hazard intensification of Central Himalayan Rivers, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-10581, https://doi.org/10.5194/egusphere-egu25-10581, 2025.
Glaciers are vital resources for regulating water availability in mountainous regions, but their reducing size due to climate change threatens this crucial role, particularly during increasingly frequent and severe snow droughts. The exceptional 2022 and 2023 snow-drought episodes in the Italian Alps provide a critical opportunity for examining the role of glacier melt in mitigating drought impacts and analyse glacier response to these extreme events. This study thus investigates the impact of the 2022-2023 snow droughts on glacier melt contribution to summer streamflow in the Italian Alps, focusing on the Aosta Valley and Lombardy regions. We utilize glacier mass balance data collected from ablation stakes scattered over different glaciers and streamflow data from the Dora Baltea and Adda rivers to validate glacier melt estimates by S3M Italy, a spatially distributed operational cryospheric model. Once validated, we use glacier melt simulations generated using the S3M Italy to analyse how glacier melt contribution to streamflow during the snow droughts of 2022 and 2023 compared to the median of 2011-2023. Our findings reveal a substantial increase in glacier melt contribution to streamflow during 2022 and 2023 snow droughts. In both regions, the contribution of glacial melt to streamflow nearly doubled or tripled compared to average values from 2011-2023. Both 2022 and 2023 droughts resulted in an earlier onset of the melt season; however, 2022 was characterized by an earlier melt peak, while 2023 showed a prolonged melt season. These results emphasize the significant contribution of glacier melt to streamflow during severe drought events, highlighting the importance of considering glacial dynamics in developing robust water management strategies for alpine environments. The increasing frequency and severity of droughts underscore the urgency of this need.
How to cite: Leone, M., Avanzi, F., Morra di Cella, U., Gabellani, S., Cremonese, E., Isabellon, M., Monti, A., Scotti, R., Pogliotti, P., and Colombo, R.: The 2022 - 2023 snow drought in the Italian Alps doubled glacier contribution to summer streamflow, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-1165, https://doi.org/10.5194/egusphere-egu25-1165, 2025.
Streamflow in central European mountain catchments is strongly influenced by snow. Rising air temperatures are causing a shift from snowfall to rainfall, a decrease in snow storage, and earlier snowmelt. Therefore, the question emerged of whether these changes could contribute to changes in catchment transit times and thus lead to acceleration of the water cycle. This study aims to quantify 1) whether the increasing number of partial snowmelt periods during winter resulting from increasing rainfall compared to snowfall affects the partitioning of the snowmelt runoff into soil and groundwater components, 2) how it affects selected hydrological signatures in late spring and early summer, and 3) examine the influence of catchment elevation on the above processes. To investigate changes in the runoff components, we used long-term simulations from 68 mountain catchments in Czechia covering the period from 1965 to 2019, using a conceptual, bucket-type catchment model. The model was evaluated against observed daily runoff and snow water equivalent (SWE). We analysed temporal trends in the fraction of fast (event) and slow (baseflow) runoff responses, calculated as monthly or seasonal fractions of the individual components to total runoff (Qfast/Qtot; Qslow/Qtot). The statistical significance of temporal trends was evaluated using the Mann-Kendall test. The elasticity index was calculated to describe how sensitive the fractions are to changes in SWE and snowmelt volume. Additionally, we investigated how the catchment characteristics, particularly elevation and geographic region, influenced these relationships to provide a more comprehensive understanding of water cycle dynamics across different mountains in Czechia. The preliminary results indicate that snow-poor years are characterized by a higher fraction of fast-response runoff during the winter months. In contrast, years with high maximum SWE lead to higher groundwater recharge which also contributed to higher low flows during late spring and early summer. Ultimately, the influence of SWE on the selected hydrological signatures becomes more pronounced with elevation.
How to cite: Fabečić, M., Acheampong, J. N., and Jeníček, M.: Accelerating Water Cycle in Mountain Catchments: The Role of Snow in Runoff Dynamics, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-6352, https://doi.org/10.5194/egusphere-egu25-6352, 2025.
Groundwater resources are increasingly affected by climate change, in which rising temperatures and altered precipitation patterns lead to shifts in recharge rates, thereby impacting water availability. Traditional hydrological data such as stream and piezometric levels provide valuable point information, however the spatial extent to which these data are relevant is not generally straightforward to determine. The limits of point measurements are particularly true in alluvial aquifers with pronounced spatial heterogeneity, as well as in mountain groundwater systems that experience significant seasonal variations in water storage. Time-lapse gravimetry (TLG), a spatially integrative hydrogeophysical method, may help to fill data gaps and evaluate spatial and temporal variability in these systems.
This study examines the spatial and temporal variability of water storage changes using time-lapse gravity data (TLG) and traditional hydrological data in the unconfined alluvial aquifer system of the pre-alpine Röthenbach catchment (Bern canton, Switzerland). We compare monthly TLG surveys with complimentary data, including time-series of groundwater head, river discharge, groundwater levels and recharge, in order to: a) test the limits of TLG in resolving groundwater storage changes, b) characterize the spatial variability in the water storage dynamics of the catchment, and c) develop a new conceptual model for this hydro-system. Our approach reveals the relationship between local gravity changes and the hydrological processes within the study catchment and provides valuable insights into the potential of TLG for hydrological and hydrogeological investigations.
How to cite: Gutiérrez-Soleibe, F., Mohammadi, N., and Halloran, L. J. S.: Gravimetry as a groundwater monitoring solution: combining hydrological and gravimetric measurements to understand a pre-alpine alluvial aquifer, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-11997, https://doi.org/10.5194/egusphere-egu25-11997, 2025.
There is a growing understanding that groundwater has an important volume in mountainous areas, controlling hydrological budgets and fluxes towards lowland basins. However, the observation of this reservoir is challenging, with less boreholes in steep and remote catchments. In the last decade, attempts to monitor groundwater via seismic waves velocity monitoring (a technique called seismic interferometry) have emerged, opening interesting avenues for mountain hydrology. Indeed, the deployment of seismic stations at high elevation is logistically more feasible and offers a good proxy for subsurface water. Here, I present three seismic deployment campaigns, aimed at monitoring groundwater dynamics in different mountainous conditions. These studies are located in 1. A catchment in the Nepal Himalayas 2. On a steep ridge in Taiwan and 3. In Alpine conditions in Switzerland. Suggestions for calibrating the method and going from seismic velocity changes to groundwater volumes are discussed with the hope to build more bridges between seismologists and mountain hydrogeologists.
How to cite: Illien, L., Andermann, C., Sens-Schönfelder, C., Cook, K., Turowski, J., Roques, C., Makus, P., Steinmann, R., Teagai, K., Armitage, J., and Hovius, N.: Mountain groundwater monitoring with seismic ambient noise: what to do next ?, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-5685, https://doi.org/10.5194/egusphere-egu25-5685, 2025.
High-mountain water storage in the form of ice, snow, and groundwater is crucial for predicting water routing to rivers. While snow and ice volumes are diminishing considerably in mountains as a result of global warming, subsurface storage volumes and transfer mechanisms remain largely elusive.
Earthquakes can act as natural experiments by changing aquifer properties and causing a hydrological response in streams. These responses can provide indications of aquifer parameters that are impossible to acquire without intrusive measurements. A range of effects including changes in streamflow, spring discharge and water table were reported. These observations can be explained by mechanisms involving water release from new sources by changing hydrological conductivity, e.g. opening new cracks or un-clogging existing conduits. The way that hydrological systems respond to seismic event can provide valuable insights into the underlying aquifers properties.
On the 25th of April 2015, which represents the end of the dry season, when rivers levels are low, a 7.8 Mw earthquake occurred in Gorkha, in central Nepal, rupturing a 140 km segment propagating from west to south-east. We observed that rivers draining the rupture area responded by a marked increase in rivers discharge. We analyzed 26 river gauging stations covering the wider rupture area. Stations within the rupture area recorded an instantaneous rise in river water level, lasting for 1-2 days after the earthquake. Stations outside the rupture area also exhibited delayed but noticeable responses, surprisingly only in the east. The 16 stations showing a marked stream flow response are spread over an area of 90,000 km², from middle to eastern Nepal.
To identify the factors influencing the patterns of response, we compared disturbed hydrographs with precipitation data, watershed characteristics, and changes in boundary conditions. For watersheds located at the western end of the rupture zone, the co-seismic response is transient while at the eastern end the response is sustained until the onset of monsoon. The time delay recorded at the outlets of large watersheds corresponds to the time required for water to travel from the seismic affected areas to the outlet.
To estimate the additional groundwater release induced by the earthquake, we applied a low-pass filter to the hydrographs. Then, we analyzed the recession curve parameters before and after the earthquake to investigate the modification of the aquifer permeability by the event.
During the dry season, rivers are predominantly groundwater fed. In the absence of recharge from precipitation, the volume of groundwater stored in aquifers decreases, leading to a decline in water table levels. Since the event occurred at the end of this period, the excess of water likely source from deep groundwater. Our estimates indicate that the event released around 1.3-1.5 km3 of additional groundwater. Furthermore, the sustained rise in water levels following (and induced by) the earthquake, suggests the presence of an important deep groundwater reservoir in the Himalayan mountain range.
Earthquakes provide valuable opportunities to investigate the dynamics of fractured bedrock aquifers in high mountains such as the Himalayas.
How to cite: Biais, Z., Andermann, C., Steer, P., Longuevergne, L., and Adhikari, B. R.: Investigating aquifer properties in the Himalayas through stream flow response to the 2015 Gorkha earthquake, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-13395, https://doi.org/10.5194/egusphere-egu25-13395, 2025.
Water temperature is one of the main drivers of water quality in rivers. Due to climate change and anthropogenic land use changes, mean river water temperature has risen during the past 30 years, and extreme water temperatures over several consecutive days, so called riverine heatwaves, occur more often. Existing research on water temperature extremes has focussed on single rivers with few water temperature measurement stations, and the occurrence and spatio-temporal variability of riverine heatwaves across Europe has not been studied yet. Therefore, we aim to (1) improve the understanding of small-scale water temperature variability and its hydro-climatic drivers by conducting an extensive 3-year field campaign in an alpine catchment and to (2) study the large-scale variability of riverine heatwaves by analysing water temperature data over Europe.
To understand small-scale water temperature variability, we measure water temperature, discharge, air temperature, and relative humidity at 15 locations within the alpine Dischmá catchment (Switzerland) along a strong elevational gradient. With this data, we describe the variability of water temperature at different time scales, assess the impact of lakes, glacier ice, snowmelt, refreezing, shading, and groundwater on water temperature, and quantify the relative importance of hydrological, atmospheric and cryospheric drivers for the development of seasonal water temperature anomalies. Preliminary results show a dampening influence of groundwater influx on the diurnal water temperature amplitude, and raise questions as to whether diurnal valley winds may cool the river.
To study large-scale water temperature variability, we compile a dataset of water temperature and discharge data across Europe. Using this dataset, we analyse changes in the occurrence of riverine heatwaves over the past 30 years. Further, we track riverine heatwaves in space, observing longitudinal propagation within one river system and the spread of riverine heatwaves across different catchments.
An improved understanding of both small- and large-scale river water temperature variability will support efforts to counteract the negative ecological and economic impacts of warming rivers.
How to cite: Grundmann, M., Astagneau, P., and Brunner, M.: Alpine river temperature drivers and riverine heatwaves across Europe, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-3220, https://doi.org/10.5194/egusphere-egu25-3220, 2025.
The water temperature of streams in montane catchments is a key harbinger of ecosystem health and water resource quality for nearby and downstream communities, a dependency that is ever increasing and sensitive to change, in the western United States and worldwide. In recent decades, representative snowfall-dominated, montane catchments such as the Sagehen Experimental Forest (hereafter, “Sagehen”), located in the eastern Sierra Nevada mountains of California, have been studied to better understand how disturbances ranging from climate-induced events, i.e., drought, wildfire, and extreme precipitation events; to human-caused events, i.e., forestry experimentation, affect stream flow and stream water temperature (SWT). Sagehen, like many catchments in the mountain West, experiences cold, wet winters and warm, dry summers, with both the quantity and timing of snow and rain being vitally important for sustaining spring and summer streamflow and buffering SWT for ecosystem resiliency. Alarmingly, climate projections for Sagehen indicate an earlier snowmelt season and more rain-on-snow events, both of which are likely to result in unknown consequences. Additionally, rising global temperatures may exacerbate the risk of hard-to-predict disturbances (i.e., wildfires and insect infestations) and resulting impacts on hydrologic systems. Stream hydrologic response, including SWT, to such events remains poorly understood due to limitations such as lack of field data and/or lack of years-long records.
To address this knowledge gap, we leverage a 12-year dataset of streamflow and SWT observations collected across Sagehen to first calibrate and then compare statistical and machine learning models for SWT. Currently, performance metrics using TempEst-NEXT, a CONUS-scale, statistical SWT forecasting model show a RMSE of 4.09°C, R2 of 0.88, NSE of 0.43 and percent bias (PBIAS) of 48% for mean daily SWT. Performance metrics for the machine-learning neural network model using daily SWT, air temperature and snow input show a strong validation period RMSE of 0.71°C, R2 of 0.98, NSE of 0.98, and PBIAS of 0.11%. Using this unique dataset, which encompasses both dry and wet periods, droughts and extreme precipitation events, as well as forest treatments, we consider the following objectives: 1) examine how climatic factors have influenced SWT response during the period of record and how response may change in the future using climate scenarios, and 2) identify what, if any, physical patterns can be discerned from observations, modeling results, and model comparisons. Preliminary analysis of daily SWT in Sagehen shows that summer 2020 had the highest daily mean SWT for the 12-year record, followed by summer 2021, and 2022. In terms of SWT variability, preliminary analysis has identified a possible relation between SWT variability and slope-face, where SWT is most buffered on the main stem, followed by the north-facing, then south-facing tributaries. Pending model analysis and cross-comparison is expected to illuminate differences in model prediction of SWT for the Sagehen basin for both the near-term and the future. Broadly, this research is expected to provide new insights on the evolution of hydrology in a montane catchment as it responds to climate variability and disturbance events.
How to cite: Corona, C., Philippus, D., Johnson, H., and Hogue, T. S.: Modeling Stream Water Temperatures for A Montane Catchment Using Observations, Statistical Models and Machine Learning, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-7617, https://doi.org/10.5194/egusphere-egu25-7617, 2025.
High-altitude non-glacial grasslands and peri-urban new-growth forests are still two poorly studied ecosystems that represent present and future conditions in the Alps. Hence, studying the functioning of these environments is crucial, especially if land surface models’ capability of representing the ecosystems’ processes is assessed.
The data are collected at two eddy covariance sites located in the Northwestern Alps, respectively on a high-altitude grassland (2550 m a.s.l.) and in a forest (650 m a.s.l. with a 25 m high mast). The data are characterised by time series spanning 365 days per year, since 2018 for the grassland site and since 2021 for the forest site.
The ecosystem and soil information (energy fluxes and actual evapotranspiration, ETa, soil moisture) obtained from measurements is combined with simulation results obtained with the land surface CLM model (The Community Land Model, NCAR, US). A rather good agreement is found between observations and simulations.
A particular focus on dry conditions in 2022 on the forest site is also presented. The results show that soil moisture, pressure head, and net radiation are more important than vapor pressure deficit, wind speed, and air temperature as ETa drivers. During the drought, despite the low soil moisture, both cases of water- and energy-limited conditions occurred. A weak effect of the drought on ETa is observed, likely due to the deep root system. The cosmic ray neutron sensor (CRNS) measurements revealed a good agreement with capacitive probes profile (CPS) ones.
This work was supported by the NODES project, funded under MUR – M4C2 1.5 of the PNRR with resources from the European Union - NextGenerationEU (Grant agreement no. ECS00000036), as well as the MUR PRIN project SUNSET (202295PFKP_003).
How to cite: Hamza, T., Gisolo, D., Gentile, A., Canone, D., and Ferraris, S.: Ecohydrological monitoring of two Alpine ecosystems representing possible broader future conditions in the Alps, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-11799, https://doi.org/10.5194/egusphere-egu25-11799, 2025.
ABSTRACT: The shift from rural to urban living has resulted in natural revegetation of abandoned rural areas located in mountainous regions. These land-use changes, combined with recent temperature and precipitation trends, affect water resources and sediment yields. Consequently, surface runoff, water infiltration, and sediment production/transport are impacted. Studies of this impact in mountainous areas are limited and partial, restricted to small basins. Therefore, this study examines the changes in both water and sediment fluxes in the northern draining region of the Ebro Basin. For the study, the SWAT+ hydrological model was employed. SWAT+ is a semi-distributed, deterministic, continuous basin model that operates on a daily time step. The model requires several inputs: a Digital Elevation Model (DEM), reservoir locations, land use map and index, soil type map and properties, as well as climatic data. The Ebro basin was divided into eight sub-basins and a hydrological model was developed for each. Calibration and validation processes were conducted in two steps: firstly, hydrological calibration and validation was performed and afterwards the process was repeated for the sediments. Firstly, hydrological calibration and validation were conducted at available and relevant gauging stations within the sub-basins. In total, over 30 stations were used as control points. The precision of the calibration and validation was evaluated using the Nash-Sutcliffe Efficiency (NSE). Secondly, sediment calibration was conducted using available reservoir bathymetry data or sediment yield estimates from scientific literature. The sediment calibration aimed to reproduce values of the same order of magnitude as those derived from bathymetry or literature data. The resulting hydrologic and sedimentologic model was re-run and NSE, maintaining or improving the NSE values obtained from the hydrological calibration. NSE values, thus, ranged from 0.53 to 0.95 depending on the gauging station. The mean NSE for the entire basin under study was 0.75, indicating that a well-established hydrologic and sedimentologic model was achieved. Future work will involve, firstly, applying climate change scenarios from CMIP6 and comparing the current results to observe the response to climate change. Secondly, generating downscaled land-use change maps to accurately represent the evolution of land-use change in each sub-basin. This approach will allow for the analysis of the impacts of climate change alone and in combination with land-use change.
ACKNOWLEDGMENTS: This work is funded by the European Research Council (ERC) through the Horizon Europe 2021 Starting Grant program under REA grant agreement number 101039181 - SEDAHEAD.
How to cite: Ortiz-Elorza, A. and Juez, C.: Impacts of Global Change on hydrologic and sedimentologic dynamics in the Northern Ebro Basin, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-4225, https://doi.org/10.5194/egusphere-egu25-4225, 2025.
Mountains play a critical role in water provision and use in the lowlands, with the timing and magnitude of runoff being key determinants of water availability. Climate change is projected to alter runoff dynamics globally. This will affect the interplay between mountain and lowland runoff and, thus, lowland water availability. While many studies have focused on runoff changes in individual river basins, occasionally contrasting lowlands and mountains, we lack information about how the magnitude and timing of mountain and lowland runoff differ across river basins worldwide and how these characteristics may change in the future. Moreover, studies examining future changes in the relevance of mountain runoff for future lowland water use beyond decadal averages are rare.
Therefore, in this study we examined differences in runoff magnitude, seasonality and interannual variability between lowlands and mountains in all large river basins globally, both in the past and under future projections. A key focus was to determine whether future changes might lead to increasing similarity between lowland and mountain runoff characteristics. We then investigated future changes in the seasonality and interannual variability of lowland surface water abstractions (LSWA) and the share stemming from mountain runoff. This second part of the study builds upon previous work (Hanus et al., 2024a) by exploring future changes in the relevance of mountain runoff for meeting lowland water demand including interannual variability.
To improve the representation of mountain runoff, we used global hydrological simulations from the Community Water Model (CWatM, Burek et al., 2020) coupled with the Open Global Glacier Model (OGGM; Maussion et al., 2019) (Hanus et al., 2024b). Future simulations were conducted until the end of the century using a low-emission (SSP1-2.6) and high-emission (SSP5-8.5) scenario.
Our results show that mountains have a lower interannual variability, a later seasonality timing and higher specific runoff magnitude compared to lowlands. In contrast, the strength of seasonality is higher or lower in the mountains depending on the region. The projected directions for the change of these runoff signatures are agreed upon in most river basins between mountains and lowlands. Only in Central Europe are all of the analysed runoff signatures projected to become more similar between mountains and lowlands.
Focusing on interannual variability, our analysis shows that the contribution of mountain runoff to lowland surface water abstractions varies substantially between years. For example, for the Po River basin, the long-term average mountain runoff contribution to LSWA in July is 58%, whereas it can reach 76% in one year. Notably, the sign in runoff anomaly agrees in most years among the lowlands and mountains in the river basins, with minimal future changes. Still, anomaly strength is mostly higher in the lowlands. The reliance of lowland water use on mountain runoff is generally the largest in years with a negative lowland runoff anomaly, even if the mountain runoff anomaly is also below average.
Overall, our study demonstrated that mountain runoff is an important water source in many world regions, especially in specific years with low lowland runoff.
How to cite: Hanus, S., Burek, P., Smilovic, M., Seibert, J., Wada, Y., and Viviroli, D.: Projected changes in the seasonality and interannual variability of lowland and mountain runoff and potential consequences for global water use, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-6638, https://doi.org/10.5194/egusphere-egu25-6638, 2025.
Climate change is projected to create substantial challenges for water resources, especially in regions like the Mediterranean, recognized as a climate change hotspot with multiple interconnected risks. This study aims to introduce a climate change impact assessment framework for the Platanovrisi mountainous river basin, Greece, which is part of the Nestos/Mesta river basin. The GR2M hydrological model was calibrated–validated using observed rainfall, temperature and streamflow data, and applied to assess climate change impacts, which were evaluated based on projections from three climate models (i.e., GFDL-ESM4, MPI-ESM1-2-HR and IPSL-CM6A-LR) and two Shared Socioeconomic Pathways (SSP) scenarios (i.e., SSP1-2.6 and SSP5-8.5). The results indicated that between 2015 and 2050, annual precipitation and discharge are projected to decrease by 13%–23% and 32%–47%, respectively, while the average temperature is expected to rise by approximately 13% (around 1°C) compared to the historical period of 1974–2014. In addition, notable changes were observed in annual and seasonal water flow regimes, with a net reduction in river flow during winter and spring, and a mild increase in autumn and summer. These changes could pose challenges for hydropower generation, irrigation water storage and agriculture, and maintenance of ecological flows. The study also highlighted significant sensitivity and variability in rainfall, evapotranspiration, and river flows depending on the selected climate model and scenario. The results can provide valuable guidance for practitioners and decision-makers to develop adaptation and mitigation strategies for sustainable water resources management in the face of climate change.
How to cite: Kourtis, I. M., Papadopoulou, C.-A., Trabucco, A., Peano, D., Sangelantoni, L., Mellios, N., Laspidou, C., Papadopoulou, M. P., and Tsihrintzis, V. A.: Climate change impact assessment in a mountainous rural basin in Greece, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-15781, https://doi.org/10.5194/egusphere-egu25-15781, 2025.
The impacts of climate change and glacier retreat are changing the hydrology of high mountain river systems, with critical implications for water management. In regions such as Central Asia, where resources and data availability are limited, accessible modeling tools are essential to support informed decision-making.
We apply MATILDA, an open-source glacio-hydrological modeling toolkit, to assess the water balance of the endorheic Issyk-Kul basin in Kyrgyzstan under changing climate conditions from 1982 to 2100. Using a semi-distributed approach, the study simulates hydrological dynamics for the tributaries of Issyk-Kul on a catchment basis. The calibration includes snow water equivalent reanalysis data, glacier mass balance observations and 31 historical discharge records, mainly from the Soviet era.
To estimate historical and future glacier evolution of the more than 800 glaciers in the basin, MATILDA is coupled with the advanced Global Glacier Evolution Model (GloGEM). This approach allows to improve the representation of glacier changes in the simulations compared to simplified glacier routines and to evaluate their suitability for hydrological modeling in high mountain catchments. The presented results of the first phase of the study focus on climate change impacts on the general water balance, runoff contributions from the cryosphere, and the resulting lake level.
By integrating public data and open source routines, the study demonstrates the potential of MATILDA to support water management in glacierized basins facing climate change.
How to cite: Schuster, P., Osmonov, A., Sauter, T., von der Esch, A., and Georgi, A.: Assessment of the Water Balance of the Glacierized Issyk-Kul Basin in Kyrgyzstan under Climate Change, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-20264, https://doi.org/10.5194/egusphere-egu25-20264, 2025.
We study impacts of prospective climate change within the Northern Po river valley, largely snow/ice fed, largely exploited for irrigation, and needing extensive water management. Using a weather driven, semi distributed hydrological model Poli-Hydro, we simulate water budget in the area, including dynamics of the cryosphere, and thereby provide river flows, including withdrawals for irrigation, and return flow thereby. In regulated catchments proper operation rules are developed to account for modified flows downstream. We then explore management, and failure under demand, and set up management strategies, focusing upon design of a (micro?) reservoirs’ system, and operation. Then, forcing the model with IPCC-AR6 scenarios of climate, we project hydrological scenarios, and we thereby stress test the management strategy to verify critical response under climate change. We then propose adaptation strategies via re-framing of reservoirs, and management strategy thereby.
How to cite: Stucchi, L., Bocchiola, D., Morgese, S., and Prando, E.: Climate change impact and water strategies for Po River until 2100, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-18556, https://doi.org/10.5194/egusphere-egu25-18556, 2025.
Posters virtual: Fri, 2 May, 14:00–15:45 | vPoster spot A
EGU25-4321 | Posters virtual | VPS11
Performance of data-driven approaches for estimating flow hydrographs from rainfall hyetographs in small mountain catchments.Fri, 02 May, 14:00–15:45 (CEST) | vPA.1
Data driven algorithms have been largely proven to be accurate tools for modelling many hydrological variables including aggregated river flows. Many studies have tested the suitability of a wide range of data-driven algorithms for predicting the recorded flows with times-steps ranging from a few minutes to monthly or even seasonal observations fed on a wide variety of inputs. They existing works often achieve brilliant performance indicators. In this work we pay our attention to a well-known hydrological process which is the flow hydrograph generation from rainfall hyetographs based on the mass conservation law within the catchment. Our assumption is that given many different physically based theories can provide accurate estimates of the expected flow hydrograph just providing the recorded hyetograph and a set of physical parameters of the catchment, data-driven approaches should also be able to successfully estimate the flow recorded hydrographs. For testing that hypothesis, we have selected two small mountain catchments (rivers Aragón in Canfranc and Valira Oriente in Andorra catchments in the Pirineos mountains in Spain and Andorra) easily parametrizable with no water depletion. We have checked the performance of different data-driven algorithms for predicting the 15-minutes recorded hydrographs fed on 15-minutes rainfall records and the set of physical variables involved in the Green-Ampt infiltration model. Over this process we have faced several issues and observed the data-driven algorithms are unable to provide the performance indicators commonly achieved in the published works.
How to cite: Zubelzu, S., Patricio, M. Á., Berlanga, A., and Molina, J. M.: Performance of data-driven approaches for estimating flow hydrographs from rainfall hyetographs in small mountain catchments. , EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-4321, https://doi.org/10.5194/egusphere-egu25-4321, 2025.
EGU25-19528 | Posters virtual | VPS11
Comparison of a Semi-Distributed Empirical Model and a Distributed Physical Model in a Snow-Covered Mediterranean Catchment Under Climate Change ScenariosFri, 02 May, 14:00–15:45 (CEST) | vPA.2
The catchments of the Quéntar and Canales reservoirs are two adjoining valleys on the north-western side of the Sierra Nevada in Spain. Canales drains the northern slope of the river Genil, with 15 linear km of peaks above 3000 meters, culminating in the highest in the Iberian Peninsula, Mulhacen, at 3479 meters. With 83 km2 above 2000 m, this river exhibits a clear nival hydrological regime. In contrast, the Quéntar basin, which collects water from the Padules and Aguas Blancas rivers, drains a smaller area with a maximum altitude of 2336 m and only 7 km2 above 2000 m. Its regime is pluvio-nival, with a much more marginal influence of snow.
To understand and predict the hydrological behaviour of these catchments under climate change scenarios, we have calibrated two different hydrological models. These models will provide the predictive tools needed to calculate river temperature and substances, particularly nitrogen (N) and phosphorus (P). The first model, SWAT (Soil and Water Assessment Tool), is a well-known conceptual semi-distributed parametric model based on linear reservoir equations that simulates snow using a modified degree-day model. The second model, NIVAL, is a distributed model based on physical processes, featuring a specific snow module that relies on mass and energy balance, specifically designed for use in the Sierra Nevada.
The two models differ significantly in terms of preparation, calibration and performance. SWAT's advantages are those of any distributed model: fast computation, easy calibration (facilitated by automatic algorithms) and a reduced need for input data. These features make SWAT a practical choice for many applications. On the other hand, NIVAL offers a more detailed representation of the hydrological processes and greater robustness to changes in scenarios outside the calibration range. This makes NIVAL particularly valuable for studying individual processes and hypothetical future scenarios.
It was expected that the flow adjustment in SWAT would be less accurate than in NIVAL, especially in the Canales basin due to the significant snow influence. However, the calibration and validation of both models on daily flows for both basins yielded very similar results in the most common statistics. For instance, the Nash-Sutcliffe Efficiency (NSE) values were around 0.63/0.70, the Kling-Gupta Efficiency (KGE) was 0.70/0.74, and the Percent Bias (PBIAS) was 2.49/19.08 for the Canales and Quéntar cases. These results demonstrate that SWAT is a reliable option for calculating total flows in historical scenarios.
Nevertheless, NIVAL's detailed process representation makes it more reliable for studying individual processes or hypothetical future scenarios. The next step in this research is to compare these models against various climate change scenarios to assess the differences in their predictions. This will help us understand the strengths and limitations of each model and improve our ability to predict and manage water resources in snow-covered Mediterranean catchments under changing climate conditions.
Aknowledments: This research has been supported by Grant TED2021-130744B-C22 funded by MICIU/AEI /10.13039/501100011033 and by the European Union Next GenerationEU/ PRTR
How to cite: Herrero, J., Galván, L., Fernández de Villarán, R., Gulliver, Z., López-Padilla, S., Pulido-Velázquez, D., and Rueda, F.: Comparison of a Semi-Distributed Empirical Model and a Distributed Physical Model in a Snow-Covered Mediterranean Catchment Under Climate Change Scenarios, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-19528, https://doi.org/10.5194/egusphere-egu25-19528, 2025.
