Assessing Coastal Aquifer Response to Projected Sea Level Rise in California

Abstract:

The rate of global sea-level rise (SLR) has been increasing over the past century, primarily due to global warming and associated melting of polar icecaps. Recent projections indicate that sea level could rise globally by more than 1 m by 2100. Potential impacts of SLR in coastal regions are a concern, especially in California which has a ~1,800 km long coastline and where >70% of the population live in coastal counties. However, information on potential impacts of SLR-driven groundwater inundation in California is limited. In this study, we examined potential impacts of SLR-driven groundwater inundation in select low-lying areas of California, including Arcata, Stinson Beach, and Malibu Lagoon, under +1 m and +2 m SLR scenarios. The results indicate that Arcata, Stinson Beach, and Malibu Lagoon will be impacted by SLR-driven inundation to different extents. For example, ~15% of present-day dry land in Malibu Lagoon will be inundated with groundwater and the lagoon will be expanded by >100% relative to present-day area under the +2 m SLR scenario. In addition, the area with shallow water table ≤2 m from the ground surface will increase substantially with SLR at Malibu Lagoon. SLR-driven groundwater inundation could be problematic in some low-lying coastal regions. Therefore, improved understanding of potential response of coastal aquifers to SLR could help in preparing for mitigation and adaptation.