WATER TABLE RISE AND ASSOCIATED HAZARDS FOR CALIFORNIA WITH HIGHER SEA LEVEL

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.