Oregon Sea Grant

Sea level rise will increase coastal hazards of flooding and erosion. Along the active tectonic margin of California, the diversity in coastal morphology complicates coastal hazard evaluations. We apply new methodologies using statewide data to evaluate potential erosion hazards from two climate scenarios. The erosion method relates shoreline change to coastal geology then applies changes in total water levels in exceedance of the toe elevation to predict future erosion hazards. Erosion along the seacliff backed shorelines was highest in the geologic units of Cretaceous marine (K) and Franciscan complex (KJf). 100-year future flood elevations were estimated using two different methods, a base flood elevation approach extrapolated from existing FEMA flood maps, and a total water level approach based on calculations of astronomical tides and wave run-up. While actual future hazards may vary from predicted, this methodology provides coastal managers with a planning tool and actionable information to guide adaptation strategies.