GROUNDWATER BASIN CHARACTERIZATION AND PRELIMINARY HYDROGEOLOGIC INTERPRETATIONS USING CALIFORNIA'S STATEWIDE AIRBORNE ELECTROMAGNETIC SURVEY DATASET

In 2021, the California Department of Water Resources (DWR) launched the Statewide Airborne Electromagnetic (AEM) Survey Project to enhance the understanding of large-scale aquifer structures across California’s groundwater basins and support SGMA implementation. Data collection concluded in 2023, yielding over 25,000 kilometers of AEM data and several thousand digitized well logs across 95 groundwater basins. To ensure accessibility, all data were published promptly, and DWR developed visualization tools for public access without the need for costly software.

The AEM Survey has provided a valuable dataset that builds upon existing local, state, and federal subsurface characterization knowledge and understanding and will be integrated into DWR's ongoing California's Groundwater - Bulletin 118 Basin Characterization program. Preliminary analyses using the AEM and related datasets demonstrate the potential to refine hydrogeologic architecture, improve texture models, and identify key features such as incised valley fills and volcaniclastic sediments. Additionally, the data help define recharge locations and detect high-salinity fluids from seawater intrusion, informing sustainable groundwater management strategies.