Climate change is impacting water resources globally. In the US Mountain West, warming is pushing watersheds beyond historical hydroclimate conditions and altering snowpack, groundwater recharge, and stream baseflow. This project investigates intermittent groundwater discharge, i.e., flow that pulses following snowmelt and ceases during late summer low-flow conditions. Here we address three research questions to better understand shifting ecohydrological baselines: (1) What groundwater flow path distributions support intermittent flow? (2) What is the chemical signature of intermittent groundwater discharge? And (3) How do groundwater age and flow duration relate to landscape geomorphological characteristics? The study will be conducted in the Sagehen Creek Basin, CA, a well-instrumented Sierra Nevada watershed with long-term climate, streamflow, and groundwater records. We will sample five intermittent groundwater sites for age-dating using CFCs and SF6, analyze major ion chemistry and field water quality parameters, deploy in-situ loggers to record flow persistence or absence, and compute high-resolution terrain metrics to evaluate landscape controls. Pending results and analysis will provide insight into how climate-driven changes in recharge and snowpack influence groundwater flow paths, water quality, and the resilience of mountain groundwater systems.
