Potential inundation due to rising sea levels in the San Francisco Bay Region

An increase in the rate of sea level rise is one of the primary impacts of projected global climate change. To assess potential inundation associated with a continued acceleration of sea level rise, the highest resolution elevation data available were assembled from various sources and mosaicked to cover the land surfaces of the San Francisco Bay region. Next, to quantify extreme water levels throughout the bay, a hydrodynamic model of the San Francisco Estuary was driven by a projection of hourly water levels at the Presidio. This projection was based on a combination of climate model outputs, an empirical model, and observations, and incorporates astronomical, storm surge, El Niño, and long-term sea level rise influences. Based on the resulting data, maps of areas vulnerable to inundation were produced, corresponding to specific amounts of sea level rise and recurrence intervals, including tidal datums. These maps portray areas where inundation will likely be an increasing concern. In the North Bay, wetlands and some developed fill areas are at risk. In Central and South bays, a key feature is the landward periphery of developed areas that would be newly vulnerable to inundation. Nearly all municipalities adjacent to South Bay face this risk to some degree. For the bay as a whole, as early as mid-century under this scenario, the one-year peak event nearly equals the 100-year peak event in 2000. Maps of vulnerable areas are presented and some implications discussed. Results are available for interactive viewing and download at http://cascade.wr.usgs.gov/data/Task2b-SFBay.