More than 16% of Earth's population relies on seasonal snowpack and glaciers for water supply, yet the mechanisms of groundwater recharge and streamflow in high elevation mountain ranges are poorly understood. Quantifying groundwater recharge is essential for groundwater management particularly in irrigated agricultural regions relying on streamflow and recharge from mountain watersheds. Precipitation (snow and rain) in California's Sierra Nevada is the dominant natural recharge mechanism for the Central Valley, a vitally important agricultural region. Frequent drought and changes in snowpack in the Sierra Nevada are expected to change recharge rates, posing challenges to water security, sustainable water management, and agriculture production. This project will integrate several research methods to investigate the most important drivers of groundwater recharge in the Kaweah River watershed in southern Sierra Nevada, and will quantify groundwater response to climate variability, droughts, and changes in vegetation. The project aims to improve hydrologic sciences education and problem-solving skills for groups underrepresented in STEM disciplines by engaging undergraduate and graduate students in research, and developing online learning modules focused on hydrologic processes of mountain catchments. The project will train high school teachers and design online educational resources for STEM teaching in high schools. By involving the Kaweah River watershed citizens in data collection, the project will increase public awareness of complex factors that affect water resources in California.
Although groundwater recharge supplies 66.5% of streamflow in arid and semi-arid mountain catchments, understanding of mountain system aquifer recharge rates and groundwater flow paths from mountains to valley aquifers is limited. This project will investigate groundwater recharge in a mountain-valley aquifer system in the Kaweah River watershed of California’s Sierra Nevada through field data collection, laboratory analysis and numerical modeling. A suite of hydrometric observations and hydrochemical tracers will measure catchment water balance dynamics, residence times of surface water and groundwater, and bedrock groundwater’s contribution to streams. An integrated hydrologic model informed by multiple sources of observations, will constrain groundwater flow paths from mountain to valley aquifers, and improve recharge estimation. Quantifying recharge and understanding the degree of connectivity between the mountain and valley aquifer system will provide understanding of the hydrologic contributions from mountain-valley systems for sustainable water resources. Results will inform development of a computationally efficient groundwater module of the Soil Moisture and Runoff simulation Toolkit (SMART), a semi-distributed hydrologic modeling framework. The novel SMART-G computational framework will investigate surface water-groundwater interactions in mountain watersheds, and predict impacts of climate variability and land cover changes on water resources. The project will engage undergraduate students in research and develop educational materials to prepare skilled workforce in hydrologic sciences. The project will train high school teachers to prepare students in STEM requirements for university admission, and involve citizen scientists to increase public awareness about water resources. Modeling tools will be disseminated worldwide and will inform policy and groundwater management decisions at the local and state level.
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.
