GSA Annual Meeting in Phoenix, Arizona, USA - 2019

Paper No. 250-2
Presentation Time: 8:25 AM


BEFUS, Kevin M.1, BARNARD, Patrick L.2, FINZI HART, Juliette2, HAYDEN, Maya3, HOOVER, Daniel J.2, JONES, Jeanne M.4, VOSS, Clifford I.5 and WOOD, Nathan J.6, (1)Civil and Architectural Engineering, University of Wyoming, 1000 E University, Dept 3295, Laramie, WY 82071, (2)U.S. Geological Survey, Pacific Coastal and Marine Science Center, 2885 Mission Street, Santa Cruz, CA 95060, (3)Point Blue Conservation Science, Petaluma, CA 94954, (4)U.S. Geological Survey, Western Geographic Science Center, Menlo Park, CA 94025, (5)National Research Program, USGS, Menlo Park, CA 94025, (6)Western Geographic Science Center, U.S. Geological Survey, 1300 SE Cardinal Court, Suite 100, Bldg. 10, Vancouver, WA 98683

Sea level rise effects on the shoaling of coastal water tables remains an unquantified hazard along most coastlines. We used hundreds of overlapping, high-resolution groundwater models to predict equilibrium water table positions along the entire California coast. We modeled the water tables for sea levels from zero to five meters above present-day conditions. We found that areas with shallow water tables today were the least responsive to sea level rise but also are most at risk to marine inundation. The loss of such areas to marine conditions resulted in overall deeper water tables near the coast, which could stress groundwater-dependent ecosystems and restrict groundwater discharge to smaller areas. The magnitude of water table rise for increasing sea levels decayed exponentially with distance inland, but this decay did not follow analytical solutions based on flow properties and geometry. These water table rise predictions also guided a hazard-exposure analysis to determine the socioeconomic impacts of the hydrogeologic responses. Output products will be made broadly available to decision makers via two user-friendly, web-based platforms.