Inundation feature set representing areas vulnerable to a 77 inch rise in sea level for the San Francisco Bay Region. This is a derivative feature set, assembled by the Metropolitan Transportation Commission (MTC), created by merging county-specific, land-only inundation feature sets. The source, county-level feature sets were produced for Adapting to Rising Tides (ART), a program led by the San Francisco Bay Conservation and Development Commission (BCDC), in September 2017. The sea level rise (SLR) scenario used to produce this data represents 77 inches (a little less than six and one-half feet) of water level above the current mean higher high water (MHHW) tidal datum. This is also considered equivalent to 36 inches of SLR plus a 100-year extreme tide. The polygons contain the extent and depth of land-only inundation (in feet) flooding of the bayside shoreline. Depth of flooding were created by subtracting a land surface Digital Elevation Model (DEM) from the water surface DEM representing the SLR scenario (MHHW + SLR). Extent of flooding were created by employing a two rule assessment to determine if an area is inundated. It must be below the assigned water surface DEM elevation value, and it must be connected to an adjacent area that was either flooded or open water. This method applies an "eight-side rule" for connectedness, where the area is considered "connected" if any of its cardinal or diagonal directions is connected to a flooded area or open water. Hydraulic connectivity assessment removes areas from the inundation zone if they are protected by levees or other topographic features that prevent inland inundation. This assessment also removed areas that are low lying but inland and not directly connected to an adjacent inundated area. The 77 inch SLR scenario can be used to approximate all extreme tide/sea level rise combinations that produce a water level in the range of MHHW + 74 inches to MHHW + 80 inches, including: - 77 inches of SLR; - 1-year extreme tide event coupled with 66 inches of SLR; - 2-year extreme tide event coupled with 60 inches of SLR; - 5-year extreme tide event coupled with 54 inches of SLR; - 10-year extreme tide event coupled with 52 inches of SLR; - 25-year extreme tide event coupled with 48 inches of SLR; - 50-year extreme tide event coupled with 42 inches of SLR, and - 100-year extreme tide event coupled with 36 inches of SLR. **In 2019, The San Francisco Bay Conservation and Development Commission released additional data to add East Contra Costa and Solano areas to the existing, 2017 data that focused on San Francisco Bay. This update did not include all the sea level scenarios produced in 2017. The 77-inch scenario was one of the ones for which data for East Contra Costa and Solano was not produced.** Source Data Produced: September 2017 MTC Publication Date: June 2019 Status: Progress: Complete Maintenance and Update Frequency: None planned Contact Information: Contact Organization: Metropolitan Transportation Commission Contact Person: Data & Visualization Contact Address: Address Type: mailing and physical Address: 375 Beale Street, Suite 800 City: San Francisco State or Province: California Postal Code: 94105 Country: United States of America Contact Voice Telephone: (415) 778-6700 Contact Electronic Mail Address: dataviz@bayareametro.gov Hours: 9:00 AM - 5:00 PM (PST) Monday through Friday

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