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FS 3.128

Upstream-downstream connectivity and impacts in the world’s water towers

Session includes ...

FS 3.230: Global change in high mountain environments: impacts on upstream water resources and downstream implications

Session status: Accepted

Content last updated: 2025-08-15 10:25:32

Online available since: 2025-01-13 20:50:18

Details

Full Title
FS 3.128: Upstream-downstream connectivity and impacts of global change in the world’s water towers
Scheduled
Talks:
2025-09-17, 10:00 - 12:00 (LT), SOWI – HS 1
Posters:
2025-09-17, 15:00 - 16:00 (LT), SOWI – Garden
Talks:
2025-09-17, 10:00 - 12:00 (LT), SOWI – HS 1

Posters:
2025-09-17, 15:00 - 16:00 (LT), SOWI – Garden
Convener
Drenkhan, Fabian
Co-Convener(s)
Lutz, Arthur; Viviroli, Daniel; van Tiel, Marit; Scott, Christopher A.; Schaffhauser, Timo; Somers, Lauren; and van Tiel, Marit
Assigned to Synthesis Workshop
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Thematic Focus
#IMC25, Adaptation, Cryo- & Hydrosphere, Hazards, Socio-Ecology, Water Resources
Keywords
Mountains, Climate change, Downstream impacts, Knowledge gaps, Adaptation

Description

Mountains, often referred to as the world’s “water towers”, play an important role in global hydrology and for the provision of water resources. This role is being altered by climate change, impacting amount, timing and quality of mountain runoff. While substantial research has focused on changes in snow and glaciers, a holistic perspective is just emerging that interconnects changes in mountains and related impacts far downstream, where mountain runoff is vital for human use and ecosystems across many regions. For this Focus Session we welcome all contributions at catchment, regional and global scales including reviews that provide new insights to and/or showcase novel methods to assess key environmental changes and corresponding impacts on interlinked mountain-lowland water systems and opportunities under climate and socioeconomic change. These can include, but are not limited to, surface and groundwater supply, disaster risks, human water use, sediments, water quality, aquatic ecosystems, sea-level rise, human culture, economy and well-being, as well as transboundary water management. At the end of this session we would like to synthesize the presented scientific progress and remaining knowledge gaps, and discuss ways forward to enhance our understanding for urgently needed climate change adaptation.

Note: As this session was merged from two other sessions, Fabian Drenkhan and Arthur Lutz are both conveners.

Registered Abstracts

ID: 3.10568

|Ostberg, Mackenzie

Ostberg, Mackenzie

Community Vulnerability to Changing Mountain Snowpacks in Canada

Ostberg, M.

Pearce, T.; Shea, J.; Wigglesworth, J.; and Hruby, D.

Abstract/Description

Climate change impacts in mountain regions, including decreasing mountain snowpack, are expected to continue and, in some instances, accelerate in the future, requiring communities to undertake adaptations. This research examined community vulnerability to changing mountain snowpacks through a mixed-methods case study of McBride and Dunster villages located in the upper Robson Valley, British Columbia, Canada. Our work is distinct from other mountain climate change studies because it explores the interactions among multiple environmental and societal forces that influence sensitivity to changing mountain snowpack and the capacity to adapt. Local lived experiences were gathered through 25 semi-structured interviews and a focus group with a total of 37 community members and thematically analyzed alongside community documents, local news, and quantitative data on snowpack and streamflow changes. Analysis revealed that residents are sensitive to decreases in mountain snowpack due to their reliance on spring run-off for freshwater. Low water availability has impacted food security, wildfire and structural suppression, and human health and well-being, while the local capacity to adapt has been undermined by the centralization of government services and resulting exodus of local people, along with their knowledge and skills. Despite a long history of coping with fluctuations in weather, recent changes, including low precipitation years related to the Southern El Niño Oscillation and heat waves, are considered by many residents to be outside tolerable ranges. Supporting adaptation is rooted in increasing local social capital and cohesion, which requires directing financial and human resources back into northern communities along with decision-making power.

ID: 3.11234

|Pellegrini, Giacomo

Pellegrini, Giacomo

Integrating hydrological, sediment dynamics and geomorphic assessments for sustainable floodplain management in the Camarones River Basin (Colombia)

Pellegrini, G.

Nardini, A. G. C.; and Mao, L.

Abstract/Description

Mountainous regions are major sediment suppliers, shaping river’s downstream geomorphic and hydrological processes. Sediment supply and geomorphic processes are particularly active in tropical environments owing to intense seasonal precipitations. These processes affect fluvial ecosystems status and increase flood risks, especially when the basins are affected by deforestation and in-channel sediment mining. In tropical regions, data scarcity complicates sediment dynamics assessment, while anthropogenic pressures affect downstream hydro-sedimentological processes and ecosystem services. This study develops in the Camarones river, which drains a 598 km² basin in northern Colombia, including parts of the steep Sierra Nevada Range, and discharges into the Camarones lagoon, a nationally protected area on the Caribbean Sea. The study aims at integrating catchment-scale hydrological and sediment budget modelling with reach-scale fluvial geomorphological assessment and field measurements of sediment transport dynamics. Hydrological modelling is conducted using HEC-GeoHMS, sediment budget estimations are performed with CASCADE, while in situ measurements of sediment transport, hydraulic variables are carried out with a mix of techniques (drone surveys, Bunte traps, Arduino and water level pressure sensors, manual Wolman surveys) within a simplified approach inspired to the River Styles Framework®. Preliminary findings highlight the potential of this integrated approach to analyze and understand sediment dynamics across multiple scales and under projections of climate change, with the aim of providing sustainable floodplain management guidelines. This research is a key component of a larger initiative funded by GCBC (UK), which explores socio-ecological perspectives on sustainable floodplain management and climate change impacts on river ecosystems and biodiversity (NATIVE project).

ID: 3.11457

|Nuñez Mejia, Santiago

Nuñez Mejia, Santiago

The paradox of choice: Evaluating climate change projections for hydrological impact models considering uncertainty and spatiotemporal aspects.

Nuñez Mejia, S.

Crespo, P.; Willems, P.; and Ochoa-Sánchez, A.

Abstract/Description

Many climate change projections are available or under development on a global, regional, and local scale. This diversity can be explained by the increases in computational power and the rising pressure as we experience the hydrological impacts of climate change worldwide. While many studies propose methodologies to evaluate General Circulation Models (GCMs) or to intercompare downscaling methods, there is a knowledge gap for hydrological impact modellers when they need to choose between using available projections or developing new ones to use as input in water resources models. To this end, we propose a methodology to evaluate the spatial and temporal aspects of precipitation and temperature projections used for hydrological modelling. Due to the broad range of temporal scales of interest, it evaluates sub-daily to yearly projections. This methodology is applied in a high mountain tropical catchment with complex orography as case study. We focus on high mountains because they are considered uncertainty hotspots due to the high spatial variability, sparse observations and reduced performance of common techniques. Our method is guided by the cascade of uncertainty concept which represents the uncertainty introduced in each step of the impact modelling chain. In the first step of the method, each projection is treated as a streamline of the cascade because it uses a limited number of scenarios, GCMs, downscaling methods and reference observational products. In a next step, precipitation and temperature indicators at hydrologically relevant scales are quantified during the historical period to evaluate the representation of the present climate in the catchment of interest. Finally, indicators during the future scenario are included to identify the signal of climate change and to detect the projected changes in the water cycle and the possible implications for water resources over a catchment prior to the development of a hydrological model. Although the selection of the best projection is neither feasible nor foreseen, this methodology aims to guide a coherent selection of available products or to identify the need to develop new ones for specific hydroclimate aspects before we continue adding layers to the already big cascade of uncertainty.

ID: 3.12215

|Fyffe, Catriona

Fyffe, Catriona

Investigating the drivers of past and future change in the cryosphere and downstream water resources in a tropical Andean basin

Fyffe, C.

Potter, E.; Shaw, T. E.; Miles, E.; McCarthy, M.; Castro, J.; Loarte, E.; Medina, K.; and Pellicciotti, F.

Abstract/Description

The Peruvian Andes contain glaciers which have undergone considerable mass loss over the past three decades and which face significant changes under future warming. Meltwater from snow and glaciers is important for water resources in this region, particularly in the dry season, and changes in the cryosphere could impact runoff regimes, downstream ecosystems and water users. To determine the drivers of past changes in the mountain water cycle, and investigate its likely future response under climate change, we run the fully distributed, hourly glacier-hydrological model TOPKAPI-ETH over the upper Rio Santa catchment in the Cordillera Blanca. We run the model from 1987 to present and then to 2100 in the future, forced in the past by bias-corrected WRF simulations, which are also used for statistical downscaling of 12 CMIP5 model projections which form a future climate ensemble. The ability of the model to replicate past glacier changes is assessed through comparison against historical glacier outlines, and we also evaluate model outputs against glacier mass balance, snow cover and gauged runoff datasets.

We find that past ENSO fluctuations have a significant impact on both glacier mass balance and the hydrological functioning of the catchment. Warmer El Niño air temperatures result in more negative glacier mass balances, but particularly negative mass balances are also found in low precipitation years which are not related to ENSO. Ice melt and on-glacier snowmelt is increased in El Niño years, resulting in an increase in discharge in highly glaciated sub-catchments. However, off-glacier snowmelt is decreased and discharges further downstream do not change significantly due to water loss from increased evapotranspiration. Despite the majority of the glaciers in the catchment facing overall negative cumulative mass balances over the past 30 years, there are exceptions, with positive balances found for the highest elevation glaciers. We also investigate the long term changes in the catchment runoff regime, demonstrating that the timing of ‘peak water’ in the dry season varies per sub-catchment depending on the degree of glacier recession. Our model outputs also allow us to explore the future changing resilience of the water cycle to predicted climate extremes.

ID: 3.12479

|Biemans, Hester

Biemans, Hester

The impact of melting glaciers and snowpacks on crop production in Asia.

Biemans, H.

Gulpen, M.; Mertzanis, N.; Lutz, A.; Khanal, S.; Immerzeel, W.; and Khaniya, M.

Abstract/Description

The high mountains of Asia, often called ‘the Third Pole’, 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 ‘Third Pole’ a very important region globally in terms of water reserves on which both water- and food security for a huge population heavily depend.
The water supply from the Third Pole mountains faces many threats. Glaciers and snowpacks are melting at unprecedented rates, and large parts of these reservoirs are likely to disappear by the end of the 21st century. The dependence of downstream populations on mountain water resources is however increasing, mainly due to increasing water needs, continuing groundwater depletion and changes in (monsoon) precipitation.
In this presentation we will show how some of the intensive agricultural systems in Asian river basins depend on the stable and reliable flow of meltwater in specific seasons, when precipitation is absent. We will show how we quantify the links between the water stored in the High Mountains of Asia and the water- and food security of the people living downstream, evaluate how those links will change in the future, and use this understanding to support adaptation design. More in general, this presentation emphasizes the need for a more integrated, holistic approach to assess the impact of changes in the mountains on downstream water users.

ID: 3.12697

|Janzing, Joren

Janzing, Joren

Networking: how the river network shapes spatiotemporal drought behavior

Janzing, J.

Wanders, N.; Verhoeve, S.; and Brunner, M.

Abstract/Description

Streamflow droughts evolve in space and time. Such spatiotemporal evolution of streamflow drought is not just driven by changing hydrometeorological conditions, but also by the river network: the drought signal from different tributaries interact as these tributaries merge. However, little is known about the exact role the river network plays in shaping such spatiotemporal drought relationships. Here, we use large-scale hydrological model simulations over Europe to study the role of the river network in shaping spatiotemporal drought relationships in different hydroclimates such as mountain and lowland regions. We apply complex network theory to study drought connections between different river branches. In particular, we focus on the spatiotemporal relationships between upstream and downstream rivers, between droughts in snow and rainfall-dominated rivers and between different river basins. We find that the stream order is important for the drought connectivity between different river branches, whereas the hydroclimatic context can determine where in a basin the drought signal emerges first. As the river network influences the temporal characteristics of the drought signal, this can also influence larger-scale spatiotemporal drought connections between different river basins. Finally, as hydroclimatic conditions are changing due to climate change, we show that such changes can also lead to changes in drought connectivity over time. Our results have implications for water management, as a better understanding of the role of the river network in shaping spatiotemporal drought behavior can help with projecting drought impacts and designing drought impact relief strategies.

ID: 3.12698

|Khaniya, Manoj

Khaniya, Manoj

A coupled cryosphere-hydrology-crop model for the integrated assessment of water and food security in the Third Pole region

Khaniya, M.

Mertzanis, N.; Gulpen, M.; Smolenaars, W.; Khanal, S.; Lutz, A.; Immerzeel, W.; and Biemans, H.

Abstract/Description

The High Mountains of Asia, i.e., the Third Pole, are among the most important water reserves in the world because of the downstream dependency, for both direct human consumption and food production, on the upstream glaciers and snow. With changing climate and subsequent alteration of snow and glacier dynamics, the region has already been identified as one of the most vulnerable, necessitating detailed understanding of the impacts of these changes. Moreover, the trajectory of socio-economic development will also play a crucial role in the interplay between future water availability, demand, and food production. As such, with the aim of quantifying the consequences of both climate change and socio-economic development in the Third Pole region at a high spatial and temporal resolution, here we couple the widely used Spatial Processes in HYdrology (SPHY) model with the Lund-Potsdam-Jena managed Land (LPJmL) model. The idea behind this one-way coupling is to improve upon the poorly represented cryosphere processes in the latter by using the SPHY model outputs from the upstream mountain sub-basins while concurrently simulating the downstream hydrology, irrigation and crop growth with LPJmL. The coupled model further incorporates spatially explicit representation of multi-cropping, along with the extensive irrigation and inter-basin transfer canals for a realistic modeling of local agriculture and irrigation. As a first application result, an initial assessment of the importance of meltwater in different parts of the region and the contribution of mountain water to irrigated agriculture is presented. An overview of the current spatio-temporal status of water availability, demand and use, along with the crop-specific water requirement and yield is also provided. Future applications of the model are expected to increase our understanding of the diverse upstream-downstream relationships over the Third Pole region and help support adaptation design through the identification of vulnerability hotspots in different basins.

ID: 3.13062

|Célleri, Rolando

Célleri, Rolando

Vulnerabilities to Water Supply in the Southern Andes: Land Use, Climate, and Infrastructure Issues

Célleri, R.

Abstract/Description

Lowland areas depend on water flowing from distant headwater regions, while Andean cities and communities are situated at these headwaters. As a result, they rely on water sourced from small catchment areas, making them particularly vulnerable to shifts in the hydrological cycle and changes in land use. Tropical Andean ecosystems, such as paramo and cloud forests, have historically provided a reliable water supply for downstream communities. However, recent shifts in land cover, land use practices, and erratic weather patterns are increasingly threatening this water supply. This study highlights some of the most urgent challenges to water security in tropical Andean communities, focusing on issues like deforestation, wetland drainage, road construction, rainfall-triggered landslides, and the construction of future dams. The city of Cuenca in the southern Andes will serve as a case study. Additionally, aging water infrastructure combined with rapid urban growth is driving an increased demand for water. This dual pressure is leading to significant conflicts among water users. Addressing these challenges requires an interdisciplinary approach to water and land use management.

ID: 3.13116

|Vreugdenhil, Mariette

| Schwaizer, Gabriele

Vreugdenhil, Mariette| Schwaizer, Gabriele

A Digital Twin for Austria for Alpine Hydrology and Future Hazards

Vreugdenhil, M.

Nagler, T.; Parajka, J.; Hasliner, B.; Massart, S.; Villegas, C.; Reimer, C.; Tanhapour, M.; Sleziak, P.; and Schwaizer, G.

Abstract/Description

Climate change is altering the Austrian Alps, including changing snow- and rainfall, which affects river discharge and has implications for water supply, hydropower, agriculture, tourism, and industry. The heterogeneity of mountains asks for high resolution methods to monitor and accurately predict changes in the water cycle in the Alps. In addition, recent studies have shown improvements in hydrological modelling of river discharge by adding soil moisture and snow cover data on top of precipitation and temperature to constrain the model. Both monitoring of water cycle components and hydrological modelling require reliable data at high resolution easily available to users with quality indicators. Recently, the European Centre for Medium-Range Weather Forecasts (ECMWF) has created the Climate Change Adaptation Digital Twin (ClimateDT), which will provide past, present, and future predictions on land surface variables at 5 km spatial resolution from 1990 to 2050 with different scenarios. Furthermore, the Copernicus Sentinel satellites provide high resolution observations providing information of the current state of the land surface, including soil moisture and snow from Sentinel-1 and Sentinel-3, respectively. Remote sensing of snow cover extent and soil moisture in mountainous areas is challenging due to shadowing effects and the many processes occurring simultaneously depending on location and height. We will present the first steps in creating a Digital Twin for Austria to monitor the water cycle in the Alps with first results of the ClimateDT products and Sentinel-based snow cover extent and soil moisture. ClimateDT soil moisture and snow depth are evaluated with the Sentinel based products. Furthermore, temperature, precipitation and soil moisture are validated with in situ observations from meteorological stations. The accuracy assessment will provide insights in the quality of the ClimateDT model for monitoring the water cycle. The work is carried out within the FFG funded Digital Twin Austria Alpine Hydrology and Future Hazards project with the goal to use the ClimateDT, along with Copernicus satellite-based data of snow extent and soil moisture, for hydrologic modelling of river discharge and to assess current and future water-related risks in the Austrian Alps.

ID: 3.13183

|Shirsat, Tejal

Shirsat, Tejal

Linking Basin Hydrology to Local Water Security in a Transboundary Glacierized Himalayan River Basin

Shirsat, T.

Boyer, E.; Hadjimichael, A.; Kulkarni, A.; Taloor, A. K.; and Scott, C.

Abstract/Description

Hindukush Himalayan (HKH) region known as the Water Tower of Asia, plays a critical role in assuring water security for billions of people and threatened ecosystems in the Indian sub-continent. Impacts of synoptic-scale changes in climatic conditions, and increasing socio-economic requirements impact the water security in the HKH. Moreover, lack of adequate considerations of local water management practices and values limits our ability to truly understand water security and devise effective solutions. In this regard, the present study aims to connect the basin-scale hydrology to water security in the Chenab River Basin at the local scale of an administrative unit by integrating qualitative and quantitative methods. The Chenab River is a major tributary of the Indus River that originates in the Lahaul range of the Western Himalayas. In this study, we analyzed the hydrological regime of the Chenab River basin having a drainage area of 28,900 km2 and an elevation range of 287 to 7044 m. The basin consists of 2,802 glaciers covering 2,864 km2, implying heavy reliance of the basin’s water security on glaciers and snowpack. The Spatial Processes in Hydrology (SPHY) model was used to estimate basin hydrological regime and contributions of water balance components i.e. snowmelt, glacier melt, rainfall runoff and baseflow/groundwater in the present. The basin hydrology is later linked to local water security by integrating model outputs with household surveys to understand the reliance of downstream villages on the local water resources. This assessment will advance understanding of the basin’s hydrological dynamics and responses at local and regional scales and provide essential insights for holistic water management in this hydrologically and institutionally complex basin.

ID: 3.13951

|León Menacho, Vladimir Alfonso

León Menacho, Vladimir Alfonso

Constructed Wetlands for bioremediation of Acid Rock Drainage in the Peruvian Andes: Implementation, monitoring and replicability

León Menacho, V. A.

Aguirre Falcón, K.; Asensi Dasi, E.; Hernández Crespo, C.; and Martín Monerris, M.

Abstract/Description

Climate change-accelerated glacial retreat and weathering of rocks with metallic sulphides generate acid rock drainage (ARD), characterised by high concentrations of H⁺, SO₄²-, Fe and other heavy metals. This natural geochemical process is a critical environmental problem in the Peruvian Andes, where ARD impacts water quality and hydrological connectivity from mountain ecosystems to downstream river systems. The community of Canrey Chico, in the Ancash region, is a unique case where ARD directly affects the local population, causing environmental and socio-economic risks due to the use of river water for agricultural and livestock activities. In response to this problem, and under a participatory approach, a Bioremediation Pilot Plant was implemented for research purposes. This plant includes constructed wetlands (CW) with different configurations, both full-scale and prototypes. The objectives of this study were: (1) design and implement CW systems, (2) monitor effluent quality for potential agricultural and livestock reuse, and (3) assess the potential for replicability of these solutions in other areas affected by ARD. The implemented CW are unique systems in terms of the water they treat. They have been designed and implemented with the participation of local people, who have traditional knowledge and an interest in improving water quality. In addition, research is being carried out to optimise these systems. As a result, a significant reduction in the concentration of SO₄²- (27±12%) and heavy metals (Fe: 88±5%, Al: 96±2%, Co: 98±1%, Cd: 79±22%, Zn: 96±2%, Cu: 90±10%, Ni: 98±1%, Be: 71±18%), as well as an increase in pH to 6.37±0.15, which allows the potential reuse of water as established by national legislation. These systems can be optimised and replicated in hydrographic units affected by ARD in the Andes and in other regions of the world with similar problems, depending on the type of water use and the needs of the population.

ID: 3.5063

|Lone, Suhail

Lone, Suhail

Isotope derived snowmelt routing in mountainous basins of western Himalaya, India

Lone, S.

Jeelani, G.

Abstract/Description

Himalayan cryospheric waters are a vital freshwater source for billions of people living in upstream and downstream regions, thereby playing a crucial role in sustaining the economic stability of the region. However, these critical water resources face significant threats from climate change, potentially disrupting the region’s economic stability. In this study, we used stable water isotopes (δ¹⁸O and δ²H) to investigate the isotopic evolution of cryospheric water and identify the primary sources of streamflow in snow and glacier dominated high-altitude catchments within the Indus River Basin. Newly deposited snow displayed a notable altitude effect, while surface snow exhibited a reverse altitude effect due to evaporation and sublimation processes. Post-depositional changes in snow led to significant isotopic homogenization of δ¹⁸O and δ²H, with isotopic exchange between firn and percolating meltwater resulting in greater enrichment of heavy isotopes in successive snow layers. Bayesian stable isotope mixing model in R indicated that snowmelt contributed significantly to streamflow in the Indus (63±1.2%) and Shyok (58±1.7%) catchments, while glacier melt dominated contributions in the Nubra (64±2.3%) and Suru (60±2.7%) catchments. Groundwater (baseflow) was found to play a critical role in sustaining river and stream flows during winter and spring, ensuring local water availability. The higher slope and intercept of the snow and glacier melt lines compared to global and local meteoric water lines indicated minimal evaporation. The findings suggest that the region’s spatially diverse, rugged topography and microclimates largely dictate the varying contributions of different sources to river flow. With a warming climate causing decreased solid precipitation, continuous glacier mass loss, and earlier snowmelt, the perennial flow of rivers is likely to be inconsistent, posing significant risks to the region’s economic and political stability.

ID: 3.9956

|Viviroli, Daniel

Viviroli, Daniel

Cascading downstream impacts of climate change in the world’s water towers

Viviroli, D.

Drenkhan, F.; Scott, C. A.; Somers, L.; and van Tiel, M.

Abstract/Description

Mountains, often called the world’s “water towers” due to their important role in global hydrology and water resources including supply for human uses and ecological processes, are interconnected with lowlands in a system that encompasses both natural resources and society. Climate change in mountain regions affects the amount, timing and quality of mountain runoff, with important downstream consequences. While mountain streamflow and corresponding climate change impacts always travel downstream, these impacts can cascade not only spatially and temporally but also causally across a wide set of social-ecological systems. Additionally, upstream-downstream teleconnections can also have important impacts that shape upstream water tower systems, for example, through infrastructure development based on priorities for downstream users.

We synthesize key environmental changes in mountain regions worldwide into an overview and point at their consequences. These include shifts in surface and groundwater availability, disaster risks, water quality, human water use, sediment transport, aquatic ecosystems, and even sea-level rise. We link these dynamics to social processes, considering culture, economy, and well-being in local and transboundary contexts. Additionally, we highlight feedback mechanisms where downstream activities shape upstream water dynamics, including infrastructure (e.g., hydropower), land and water use (roads, mining, tourism), and conservation (glacier protection, low-impact recreation). Our review underscores the importance of an integrated framework for advancing the understanding of interconnected mountain-lowland systems to inform sustainable water management and policy development in rapidly changing mountain regions and beyond.

ID: 3.11532

|Hanus, Sarah

| Viviroli, Daniel

Hanus, Sarah| Viviroli, Daniel

Global variability and future changes in mountain runoff contributions to lowland water use

Hanus, S.

Burek, P.; Smilovic, M.; Seibert, J.; Wada, Y.; and Viviroli, D.

Abstract/Description

Mountains play a crucial role in global water resources by generating disproportionally high runoff and delaying its release through snow and ice storage. This study quantifies the contribution of mountain runoff to lowland surface water withdrawal (LSWW) across all river basins larger than 10,000 km² worldwide, focusing on seasonal and interannual variability in the recent past. Additionally, we explore projected changes in lowland-mountain water interactions under climate and socio-economic scenarios.
Our results show that 15% of annual LSWW depend entirely on mountain runoff, with monthly variations ranging from 9% to 23%, highlighting strong seasonal reliance. An additional 51% of annual LSWW can originate from either mountains or lowlands. Under the SSP5-8.5 scenario, the absolute volume of lowland water withdrawal reliant on mountain runoff is expected to rise due to socioeconomic developments. At the same time, its relative share may decline on average in many basins as lowland precipitation increases. However, LSWW exhibits substantial interannual variability, with mountain runoff being most critical in years with low lowland runoff. While relative interannual runoff variability is lower in mountain regions than in lowlands in 70% of river basins, the absolute magnitude of runoff fluctuations is higher in mountain regions in nearly 70% of basins.
Our findings highlight the complex and evolving relationship between mountain runoff and lowland water use and reveal a large heterogeneity across river basins worldwide. Understanding these dynamics is essential for ensuring water security in both mountain and lowland regions as global environmental and socio-economic conditions change.

Submitted Abstracts

ID: 3.5063

Isotope derived snowmelt routing in mountainous basins of western Himalaya, India

Suhail Lone
Jeelani, Gh

Abstract/Description

ID: 3.5368

The Ecosystems boost the Water Security in the Central Provinces of Panama

Alberto Pascual

Abstract/Description

The Santa Maria Watershed, has an extension a territory occupies a total area of 3326 km², with a length total of 168 km, representing 4.56% of the land of Panama. Identified as one of the country’s priority catchments it represents a water source for more than 200,000 people living in 15 Local Governments.

The water that’s flow in the system of rivers is generated by physical, chemical and biological characteristics from mountain, grassland and wetland ecosystems, from the source of the river in the upper part, passing through the urban centers and until it drains into the sea, there are multiple landscapes that intervene, are linked and depend of each biome for work together.

ID: 3.9794

Hydroclimatic role of the Alps as a source of precipitation on European agricultural land

Nike Chiesa Turiano
Tuninetti, Marta; Laio, Francesco; Ridolfi, Luca

Abstract/Description

The Alps are vital in generating both perennial and seasonal runoff through snow and ice melting, providing a fundamental water supply to downstream ecosystems and human activities, particularly agriculture. However, the relevance of mountains as water reservoirs for lowlands stands also in their role as evapotranspiration sources. 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. The recycling and downstream effects of changes in ET are not only hydrological but extend to economic and socio-political dimensions. Understanding these interactions is vital to addressing challenges in water resource management and agriculture sustainability. While the dependency of lowland agricultural production on surface and groundwater deriving from snow and glacier cover over the Alps has been widely studied, research on the atmospheric link between the Alps and European agricultural land remains limited. This study addresses this gap by examining the geographical destination of evapotranspired water from the Alps and identifying quantitative water vapor links between alpine and agricultural regions with particular attention to crop-growing seasons and precipitation patterns. To effectively evaluate the fate of evapotranspired water, we employed the yearly reconciled outputs of 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.

ID: 3.9956

Cascading downstream impacts of climate change in the world’s water towers

Daniel Viviroli
Drenkhan, Fabian; Scott, Christopher A.; Somers, Lauren; van Tiel, Marit

Abstract/Description

ID: 3.10568

Community Vulnerability to Changing Mountain Snowpacks in Canada

Mackenzie Ostberg
Pearce, Tristan; Shea, Joseph; Wigglesworth, Jennifer; Hruby, David

Abstract/Description

ID: 3.11234

Integrating hydrological, sediment dynamics and geomorphic assessments for sustainable floodplain management in the Camarones River Basin (Colombia)

Giacomo Pellegrini
Nardini, Andrea Gianni Cristoforo; Mao, Luca

Abstract/Description

ID: 3.11457

The paradox of choice: Evaluating climate change projections for hydrological impact models considering uncertainty and spatiotemporal aspects.

Santiago Núñez-Mejia
Crespo, Patricio; Willems, Patrick; Ochoa-Sánchez, Ana

Abstract/Description

ID: 3.11532

Global variability and future changes in mountain runoff contributions to lowland water use

Sarah Hanus
Burek, Peter; Smilovic, Mikhail; Seibert, Jan; Wada, Yoshihide; Viviroli, Daniel

Abstract/Description

ID: 3.11656

Will rock glaciers buffer alpine streams against climate change?

Scott Hotaling
McGrath, Dan; Khatiwada, Ashlesha; Gianniny, Gordon; Pomeranz, Justin; Caskey, Simeon; Finn, Debra; Tronstad, Lusha

Abstract/Description

Climate change is dramatically impacting mountain ecosystems around the world. Perhaps the most visceral of these impacts is the ongoing recession of glaciers and perennial snowfields. However, surface glaciers and snowfields are not the only perennial ice features in mountain landscapes. Many forms of subsurface ice (e.g., rock glaciers) are also present and play an important, albeit understudied, role in water availability and aquatic ecosystem integrity in mountain systems. Theory predicts that surface ice features that are exposed to ambient conditions will recede faster than subsurface ice that is insulated by debris cover. A limited amount of evidence supports this expectation. Since 2015, we have been monitoring high-alpine streams in the Teton Range, USA fed by three different sources—surface glaciers, rock glaciers, and seasonal snowpack—to understand the fate of aquatic ecosystems amidst climate change and how different sources may yield differing rates of change. In 2014 and 2022, LiDAR data was also generated for the Teton Range. By pairing our 10+ years of aquatic monitoring data with physical change inferred from LiDAR, we were able to gain rare insight into the links between physical change to ice sources and downstream ecosystems. Specifically, we found that rock glaciers in the Teton Range have been resistant to climate-induced ice loss while surface ice features have seen dramatic declines. However, these physical changes have not been mirrored in nearby streams. For instance, streams fed by seasonal snowpack and small perennial ice features have warmed rapidly during the summer while streams fed by surface glaciers and rock glaciers have remained largely unchanged.

ID: 3.12215

Investigating the drivers of past and future change in the cryosphere and downstream water resources in a tropical Andean basin

Catriona Fyffe
Potter, Emily; Shaw, Thomas E.; Miles, Evan; McCarthy, Mike; Castro, Joshua; Loarte, Edwin; Medina, Katy; Pellicciotti, Francesca

Abstract/Description

ID: 3.12479

The impact of melting glaciers and snowpacks on crop production in Asia.

Hester Biemans
Gulpen, Marijn; Mertzanis, Nikos; Lutz, Arthur; Khanal, Sonu; Immerzeel, Walter; Khaniya, Manoj

Abstract/Description

ID: 3.12697

Networking: how the river network shapes spatiotemporal drought behavior

Joren Janzing
Wanders, Niko; Verhoeve, Steye; Brunner, Manuela

Abstract/Description

ID: 3.12698

A coupled cryosphere-hydrology-crop model for the integrated assessment of water and food security in the Third Pole region

Manoj Khaniya
Mertzanis, Nikos; Gulpen, Marijn; Smolenaars, Wouter; Khanal, Sonu; Lutz, Arthur; Immerzeel, Walter; Biemans, Hester

Abstract/Description

ID: 3.13062

Vulnerabilities to Water Supply in the Southern Andes: Land Use, Climate, and Infrastructure Issues

Rolando Célleri

Abstract/Description

ID: 3.13116

A Digital Twin for Austria for Alpine Hydrology and Future Hazards

Mariette Vreugdenhil
Nagler, Thomas; Parajka, Juraj; Hasliner, Beat; Massart, Samuel; Villegas, Carina; Reimer, Christoph; Tanhapour, Mitra; Sleziak, Patrik; Schwaizer, Gabriele

Abstract/Description

ID: 3.13183

Linking Basin Hydrology to Local Water Security in a Transboundary Glacierized Himalayan River Basin

Tejal Shirsat
Boyer, Elizabeth; Hadjimichael, Antonia; Kulkarni, Anil; Taloor, Ajay Kumar; Scott, Christopher

Abstract/Description

ID: 3.13556

Assessment of Climate Change Impacts on Run-of-River Hydropower Production in Madi River Basin, Nepal

Shiksha Bastola

Abstract/Description

Hydropower remains the dominant renewable energy source globally, yet its production, particularly in Run-of-River (RoR) projects, is highly sensitive to climate change (CC) due to its dependence on streamflow availability. This study assesses the impacts of CC on hydropower generation, identifying both risks and opportunities. A comprehensive framework integrating high-resolution climate data development, hydrological modeling, and hydropower assessment is utilized to evaluate future hydropower production under changing climatic conditions.
Daily gridded observational data (0.05° × 0.05° resolution) from 1981 to 2010 were developed and used to downscale and bias-correct 18 Global Climate Models (GCMs) from CMIP6 for both historical (1981–2010) and future (2015–2100) periods. The Soil and Water Assessment Tool (SWAT) hydrological model is employed to simulate future streamflow, which is then used to estimate hydropower production at two operational and two planned RoR projects in the Madi River Basin, Nepal. Two future time periods—Near Future (NF: 2025–2054) and Far Future (FF: 2055–2084)—are analyzed under two Shared Socioeconomic Pathways (SSP245 and SSP585).
Results indicate that under the baseline design discharge, winter months show a significant increase in flow, while total annual production exhibits only a slight rise. However, when revised design discharge based on future climate projections is considered, monsoon-season hydropower production is projected to increase substantially compared to the baseline, with a similar trend in non-monsoon months. These findings suggest that hydropower developers must reassess design specifications to optimize power generation and revenue.
The study highlights the necessity of integrating climate resilience into hydropower planning and operations. Findings on production variability provide valuable insights for policymakers and stakeholders to enhance climate adaptation strategies. Additionally, the proposed methodology is adaptable for data-scarce regions, facilitating climate impact assessments and supporting sustainable hydropower development in developing nations.

ID: 3.13951

Constructed Wetlands for bioremediation of Acid Rock Drainage in the Peruvian Andes: Implementation, monitoring and replicability

Vladimir Alfonso León Menacho
Aguirre Falcón, Kiara; Asensi Dasi, Enrique; Hernández Crespo, Carmen; Martín Monerris, Miguel

Abstract/Description

FS 3.127: Mountain futures – Assessing challenges and co-producing solutions to mountain-social-ecological futures

FS 3.129: Responses of Mountain Ecosystems in Asia to recent climate change

FS 3.128

Upstream-downstream connectivity and impacts in the world’s water towers

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