Collaborative Research: Groundwater-surface water interactions in tropical alpine catchments and their influence on sources and stability of water supply during glacial recession

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Alpine watersheds and the ice and snow they contain are one of the most important sources of fresh water in the world, and mountain regions that are dominated by glaciers are especially sensitive to climate change. Melting glaciers in the semi-arid tropics currently provide a large component of annual runoff and buffer highly seasonal precipitation regimes, but ongoing glacier recession is predicted to make alpine runoff smaller in volume and more temporally variable, stressing water resources. Previous research suggests that groundwater aquifers in proglacial catchments are an important storage reservoir during dry seasons, and will likely play a dominant role in streamflow generation under future non-glacierized conditions. Despite their importance, little is known about fundamental hydrogeologic processes governing the interaction of surface water and groundwater in proglacial catchments. The investigators on this grant will study the interactions between surface water and groundwater reservoirs in proglacial meadow landforms in the Andes of Peru, estimate their storage volumes, and quantify contributions to streamflow. The research plan integrates a creative combination of field methods to directly quantify groundwater-surface water interactions (GWSWI) in remote, data-poor glacierized catchments and describe the relative hydrologic influence of groundwater storage and melting glaciers. The objectives of the proposed project are to: (1) measure gains and losses of water between stream channel reaches and groundwater stored in proglacial meadows, moraines, talus slopes, and alluvial fans in wet and dry seasons; (2) measure and map subsurface structures, properties, and water content of meadow aquifers and estimate storage volumes; and (3) determine the impact of GWSWI on surface water chemistry and on hydrochemical mixing models used to estimate glacial melt.The proposed research addresses unknown aspects of proglacial watershed hydrology, and the results will expand the current state of knowledge about groundwater storage and its interaction with surface water resources in tropical glacierized catchments and alpine watersheds. Conclusions from this study could transform alpine hydrologic modeling, which typically ignores or simplifies groundwater storage. The results of the proposed research will be broadly relevant to hydrologists, glaciologists, and physical and human geographers, as well as to water resource managers, development planners, agricultural engineers, municipalities and local governments, indigenous communities, and industrial sectors (hydroelectric and mining). Tropical glacierized mountain ranges are undergoing rapid environmental and demographic shifts and are especially susceptible to climate change and water stress, and this project will contribute to the understanding and prediction of water resources vital to human livelihoods. Education and outreach programs will enhance long-term connections with local community groups, local governments, and Peruvian researchers, and this effort will continue to engage the broader community of water users in the Andes.This project is co-funded by the Hydrologic Sciences and the International Science and Engineering Programs.