This vector dataset depicts the 1% annual flood boundary (otherwise known as special flood hazard area or 100 year flood boundary) for its specified area. The data set was generated by heads-up-digitizing flood insurance rate maps available from FEMA's Map Service Center. These maps are for informational use only and should not be used for engineering or insurance purposes. Contact your local floodplain administrator for more information.

This dataset contains the scanned, paper flood insurance rate maps (FIRMs) developed by FEMA and available from the Mapping Service Center.

This dataset contains the scanned, paper flood insurance rate maps (FIRMs) developed by FEMA and available from the Mapping Service Center.

The National Flood Hazard Layer (NFHL) data incorporates all Digital Flood Insurance Rate Map(DFIRM) databases published by FEMA, and any Letters Of Map Revision (LOMRs) that have been issued against those databases since their publication date. The DFIRM Database is the digital, geospatial version of the flood hazard information shown on the published paper Flood Insurance Rate Maps(FIRMs). The primary risk classifications used are the 1-percent-annual-chance flood event, the 0.2-percent-annual-chance flood event, and areas of minimal flood risk. The NFHL data are derived from Flood Insurance Studies (FISs), previously published Flood Insurance Rate Maps (FIRMs), flood hazard analyses performed in support of the FISs and FIRMs, and new mapping data where available. The FISs and FIRMs are published by the Federal Emergency Management Agency (FEMA). The specifications for the horizontal control of DFIRM data are consistent with those required for mapping at a scale of 1:12,000. The NFHL data contain layers in the Standard DFIRM datasets except for S_Label_Pt and S_Label_Ld. The NFHL is available as State or US Territory data sets. Each State or Territory data set consists of all DFIRMs and corresponding LOMRs available on the publication date of the data set.

This dataset contains the scanned, paper flood insurance rate maps (FIRMs) developed by FEMA and available from the Mapping Service Center.

,

A) This data describes the Special Flood Hazard Areas (SFHA's) pursuant to the Federal Emergency Management Agency's (FEMA's) Flood Insurance Rate Map (FIRM) for the City and County of San Francisco. B) These map products were created by FEMA and you can find more information on their creation on the following page: https://www.fema.gov/flood-maps/products-tools/products C) These maps are updated periodically in light of new information if flooding conditions change for a jurisdiction. This occurs on an as needed basis and is coordinated through the D) In order to use this dataset it is important to know what each zone designation means. You can find these designations below -- Zone AE, AO, and VE (AREAS WITH HIGH FLOOD RISK (SPECIAL FLOOD HAZARD AREAS; REGULATIONS APPLY): Properties within SFHAs are subject to flooding during the 1-percent-chance flood, a flood with a 1 percent chance of occurrence in any given year (also referred to as the Base Flood or 100-year flood). Zone D (AREA OF UNDETERMINED FLOOD RISK): In San Francisco, Zone D is an area of possible, but undefined, flood risk for waterfront piers operated by the Port of San Francisco. Zone X Shaded or Unshaded (AREA OF LOW OR MINIMAL FLOOD RISK): "Shaded" Zone X represents areas of moderate or low flood risk – these areas are subject to inundation during a flood having a 0.2-percent-annual-chance of occurrence, or during the 1-percent-annual-chance flood with depth less than 1 foot. "Unshaded" Zone X represents areas of minimal flood risk or areas that FEMA did not study or map. E) For regulatory implications of map, see: https://onesanfrancisco.org/San-Francisco-Floodplain-Management-Program For more detailed information on specific properties impacted by FIRM Map, see: https://sfplanninggis.org/PIM/

The Digital Flood Insurance Rate Map (DFIRM) Database depicts flood risk information and supporting data used to develop the risk data. The primary risk classifications used are the 1-percent-annual-chance flood event, the 0.2-percent-annual-chance flood event, and areas of minimal flood risk. The DFIRM Database is derived from Flood Insurance Studies (FISs), previously published Flood Insurance Rate Maps (FIRMs), flood hazard analyses performed in support of the FISs and FIRMs, and new mapping data, where available. The FISs and FIRMs are published by the Federal Emergency Management Agency (FEMA). The file is georeferenced to earth's surface using the UTM projection and coordinate system. The specifications for the horizontal control of DFIRM data files are consistent with those required for mapping at a scale of 1:12000.

For this revision, STARR conducted over 38 miles of revised Coastal Hazard Analysis that included computing wave runup. STARR utilized 79 transects in this study. No new detailed riverine studies were conducted as part of this countywide FIS. For riverine areas, floodplain boundaries were remapped as part of the countywide update to reflect more recent or more detailed topographic and base map data for the county. The floodplain mapping updates consisted of a mixture of redelineation and rectification (refinement) of existing flood boundaries based on the best topographic data and aerial photography available at the time of the study. Redelineation was limited to areas were new, quality topographic data was available and Base Flood Elevations were previously defined. Redelineation was completed on the detailed study areas of the Naselle River, Salmon Creek and South Fork Naselle River. The detailed study reaches along Ward, Wilson and Whitcomb Creeks near the City of Raymond and the Willapa River near Lebam are not covered by new topographic data and was converted to digital format by digitizing the effective FIRMs and refined by making small adjustments to fit the floodplains to new aerial photography. Approximately 4.3 stream miles, including portions of Naselle River and Salmon Creek were studied with base level methods (Zone A). The boundary of the 1-percent-annualchance flood for the South Fork Naselle River near its confluence with Cement Creek was refined by making adjustments to fit the floodplains to new aerial photography and the new topographic data. Those approximate method reaches not covered by new topographic data were converted to digital format by digitizing the effective FIRMs and refined by making small adjustments to fit the floodplains to new aerial photography to ensure that they overlay the water course they represent. These areas include portions of Salmon Creek and Willapa River.