The sea level rise maps depict low-lying areas and inundation above mean higher high water (MHHW) levels resulting from projected sea level rise. Maps were generated using NOAA’s Sea Level Rise Viewer application (https://coast.noaa.gov/slr/), which uses a modified bathtub approach or linear superposition method to identify inundated areas. The maps take into account local tidal variability and the hydroconnectivity of inundated areas. Inundation is shown as it would appear during MHHW—the average of the higher high water height of each tidal day observed over the National Tidal Datum Epoch {~19 years} (excludes wind driven tides). Low-lying areas depict hydrologically “unconnected” areas that may flood; a more detailed analysis of these areas is required to determine whether they flood given the chosen sea level rise (SLR) value. Both hydrologically connected and unconnected areas are determined solely by how well the elevation data capture the area’s hydraulics.

Sources: National Oceanic and Atmospheric Administration (NOAA) National Ocean Service (NOS). 2010. Technical Considerations for Use of Geospatial Data in Sea Level Change Mapping and Assessment. NOAA NOS Technical Report. Silver Spring, MD: NOAA NOS.