SPATIOTEMPORAL TRENDS IN MOUNTAIN AQUIFER RECHARGE

High-elevation mountain aquifers play a major role in recharging adjacent valley aquifers. Mountain Aquifer Recharge (MAR) consists of precipitation and streamflow infiltration into mountain aquifers, indirectly recharging valley aquifers. Therefore, understanding of MAR dynamics is a critical element of water resources planning. However, little is known about the magnitude of MAR and its variability in response to changes in climate. We improved upon existing recession-based storage-discharge functions to estimate MAR in 280 watersheds in the western United States. We conducted a sensitivity analysis of MAR estimates using Variogram Analysis of Response Surfaces (VARS), and validated MAR estimates by comparing with in-situ well observations and ParFlow-CLM simulations. Finally, we explored the relationships between the MAR estimates and physical characteristics of study watersheds. These datasets provide valuable insights into the role of mountain aquifers in hydrology, and enable improved management of water resources. Our improved MAR estimation technique can also be applied to any anthropogenically unaffected watershed.