Collaborative Research: Determining the eco-hydrogeologic response of tropical glacierized watersheds to climate change: An integrated data-model approach

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Recent rapid glacier retreat, especially in tropical regions such as the Ecuadorian Andes, raises important questions about water resources. Understanding the current effects of glacier retreat on water supply in these regions can shed light on future water security threats in snow and ice-covered mountainous watersheds worldwide. Glaciers are the "water towers" of the mountains: they store ice during wet periods and gradually release meltwater during dry periods. However, whether groundwater aquifers serve as extended reservoirs and whether plants also take up significant glacial meltwater remain unresolved questions. These uncertainties make it difficult to predict the future reliability of water supply in mountainous watersheds, as glacier melt first accelerates and then eventually disappears, and as plants move to higher elevations in response to warming temperatures. This project will develop a new and general computational watershed model that will incorporate chemical and isotopic data for tracing water flow source regions, as well as measurements from innovative low-cost, open-source environmental monitoring technologies. Results from the model can inform communities that rely on stream discharge from ice and snow-covered mountainous watersheds about present with regard to future water resources vulnerabilities, and can facilitate adaptation strategies as glacier retreat accelerates. The recession of glaciers will curtail their ability to modulate river discharge and its variability. Studies of this hydrologic consequence typically classify meltwater and groundwater as distinct contributors to streamflow, but this oversimplifies the potentially complex relationships among glaciers, their underlying groundwater systems, and ecohydrologic pathways. The investigators propose to assess these relationships using an integrated data-model approach in four rapidly changing, glacierized Ecuadorian watersheds, two each at Volcán Chimborazo and Volcán Cayambe. This work will produce a new isotope-enabled watershed model with reactive transport, to which data assimilation will be introduced in order to condition uncertain simulations in data-sparse watersheds with robust environmental tracers. Open-source data loggers and sensors for measuring model input data will further advance critical-zone process understanding beyond data-intensive sites to remote settings that are undergoing some of the most rapid environmental change in the world. This work will shed light on less-studied volcanic ranges that potentially facilitate greater infiltration of meltwater through their fractured bedrock, as well as expand the established water-resources focus on glacier retreat to also consider vegetation shift when examining the hydrologic response of glacierized mountainous watersheds to glacier retreat.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.