Adapting To Rising Tides Bay Area Sea Level Rise and Shoreline Analysis Maps

The regional flooding and shoreline overtopping analysis maps provided in the ART Bay Shoreline Flood Explorer website capture permanent and temporary flooding impacts from sea level rise scenarios from 0- to 108-inches above MHHW (mean higher high water) and storm surge events from the 1-year to the 100-year storm surge. The process used to develop the maps included discussions with key stakeholders in each county, who reviewed the preliminary maps and provided on-the-ground verification and supplemental data to improve the accuracy of the maps. The maps and information produced through this effort can inform adaptation planning, assist in managing climate change risks, and help identify trigger points for implementing adaptation strategies to address sea level rise and flooding hazards, at both local and regional scales. The Flood Explorer maps were produced using the latest LiDAR topographic data sets, water level outputs from the FEMA San Francisco Bay Area Coastal Study (which relied in hydrodynamic modeling using MIKE21) and the San Francisco Tidal Datums Study. The 2010/2011 LIDAR applied (collected by USGS and NOAA at a 1-m resolution) was further refined through the stakeholder review process and integration of additional elevation data where available. The Flood Explorer also includes the regional shoreline delineation developed by the San Francisco Estuary Institute to represent coastal flooding and overtopping throughout the Bay Area. In sum, the maps include: 1) Flooding at ten total water levels that capture over 90 combinations of future sea level rise and storm surge scenarios; 2) Shoreline overtopping maps for all ten total water levels that depict where the Bay may overtop the shoreline and its depth of overtopping at that specific location. Coupled with the flood maps, the overtopping data can help identify vulnerable shoreline locations and their respective flow paths that could lead to inland flooding, and; 3) Hydraulically disconnected low-lying areas that represent areas that may be vulnerable to flooding due to their low elevation. These areas are not directly within flooding locations, but could be connected to flood waters through culverts and storm drains that are not captured in this analysis.