Abstract ID: 3.13323 | Accepted as Talk | Talk/Oral | TBA | TBA

The livelihoods of millions globally rely on meltwater from glacierized catchments, which serve as essential sources of drinking water, agriculture, and hydropower. However, climate warming is significantly altering the water storage functions of these catchments, creating major challenges for water resource management in mountain regions. In recognition of the United Nations’ designation of 2025 as the International Year of Glacier Protection and the commitment to Sustainable Development Goal 6 (Clean Water and Sanitation), it is crucial to understand and address these changes while developing adaptive management strategies. Despite their importance, the relative contributions of glacier melt, snowmelt, precipitation, groundwater, and other endmember sources to streamflow remain poorly quantified in many glacierized regions. This knowledge gap hampers efforts to predict and manage water resources under changing climatic conditions. Isotope-based techniques provide a powerful means to distinguish and quantify these contributions, offering valuable insights into the current and future availability of water in glacierized catchments. As part of the International Atomic Energy Agency’s (IAEA) coordinated research project, Understanding Hydrological Processes in Glacierized Catchments under Changing Climate using Isotope-Based Methodologies, we developed a comprehensive database of isotopic signatures for key streamflow endmembers. 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. Our database includes stable isotopes of oxygen (δ¹⁸O) and hydrogen (δ²H) of endmembers, compiled from over 80 published studies worldwide and supplemented with our own collected data from study areas spanning South America, North America, Europe and Asia. This framework provides expected variations in isotopic signature of endmembers in different regions and supports the assessments of how contributions shift with seasonal and inter-annual climate variations. These insights are critical for evaluating changes in total discharge volumes and informing sustainable water management strategies to mitigate the impacts of climate change on mountain hydrology.