157 Exploring Groundwater Recharge and Management: Managed Aquifer Recharge and Other Innovative Tools for Water Supply Development and Operations

Growing demand for water has highlighted the need to understand aquifer recharge to improve groundwater management and production methods. This session explores groundwater recharge and innovative water supplies and infrastructure. Topics include evapotranspiration, vadose zone processes, brackish groundwater desalination, managed aquifer recharge, stormwater management, and others.

Tuesday, 21 October 2025
8:00 AM - 12:00 PM
HBGCC, 209

Where Did the Water Go? Evaluating Groundwater Recharge and Evapotranspiration Dynamics in Snow-Dominated, Forested Upland Watersheds of the Upper Lake Mary Area, Arizona

Paper number: 157-13
Program: Technical Sessions
Time: 11:15 AM – 11:30 AM

Authors

Abstract

In northern Arizona, forested upland recharge areas play a critical role in sustaining regional groundwater supplies, yet hydrologic processes remain poorly understood due to high rates of evapotranspiration (ET) and complex subsurface conditions. This study quantifies groundwater recharge using a water balance approach. These findings will enhance groundwater modeling efforts, inform forest management, and guide water policy in karst-influenced, semi-arid environments largely dictated by winter precipitation. The study area and surrounding region provides aquifer recharge through fractured zones, faults, and karst features. Post-colonial forest management practices have led to increasingly dense canopy cover, reducing the soil moisture. In this edition of the long-term paired watershed study in the Flagstaff Upper Lake Mary area,  additional instrumentation in the form of LI-COR ET instruments mounted on portable trailer towers and METER LI-COR Terros 11 volumetric water probes are installed into the study watersheds to improve instrumentation and compare measured values for a water balance to modeled values. This study examines (1) How to use volumetric soil moisture data to convert modeled PET to AET in a water limited system. (2) Do soil moisture measurements differ significantly between the external COSMOS station and in-situ TDR sensors? (3) Can groundwater transit time from the highly fractured ephemeral channels to nearby city wells be quantified? Using ET towers and TDR probes installed at three depths, data was collected across the seven sub-watersheds receiving varying levels of forest treatment in the upper Lake Mary paired watershed study. Results indicate a statistically significant difference between PET and AET measurements, enabling improved recharge estimates and providing confirmation of shallow subsurface connectivity via dye transport.

Geological Society of America Abstracts with Programs. Vol. 57, No. 6

doi: 10.1130/abs/2025AM-414716

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