Floodplains in Atlanta Region

This layer was developed by the Research & Analytics Division of the Atlanta Regional Commission and represents the 100-year and 500-year floodplain data as delineated on Flood Insurance Rate Maps (FIRMs) published by FEMA. Features captured from the paper FIRMs include floodplain boundaries, political boundaries, FIRM panel areas, and USGS 7.5-minute quadrangle boundaries. Potential applications of this "Q3" flood data include floodplain management, hazards analysis and risk assessment. In addition, the risk zones serve to establish premium rates for flood insurance offered through the National Flood Insurance Program. For more information, go to https://msc.fema.gov. Attributes: FIPS Standard 5-digit State and County FIPS codes. Definition source is from Federal Information Processing Standard (FIPS), National Institute of Standards & Technology (NIST); first 2 digits for state, last 3 digits for county. COMMUNITY Identifies a county, city, or other community responsible for flood plain management. Numeric value assigned by FEMA,(0..9999). FIRM_PANEL Eleven-digit alpha-numeric code identifies portion of community covered or not covered by a FIRM panel. Code comprises a unique alpha-numeric sequence based on FIPS and FEMA Community and Panel identification. QUAD USGS 7.5-minute quadrangle identifier. ZONE Flood hazard zone designation. Multiple Codes refer to "Q3 Flood Data Specifications" VALUES DESCRIPTION V An area inundated by 100-year flooding with velocity hazard (wave action); no Base Flood Elevation (BFEs) have been determined. VE An area inundated by 100-year flooding with velocity hazard (wave action); BFEs have been determined. A An area inundated by 100-year flooding, for which no BFEs have been determined. AE An area inundated by 100-year flooding, for which BFEs have been determined. AO An area inundated by 100-year flooding (usually sheet flow on sloping terrain), for which average depths have been determined; flood depths range from 1 to 3 feet. AOVEL An alluvial fan inundated by 100-year flooding (usually sheet flow on sloping terrain), for which average flood depths and velocities have been determined; flood depths range from 1 to 3 feet. AH An area inundated by 100-year flooding (usually an area of ponding), for which BFEs have been determined; flood depths range from 1 to 3 feet. A99 An area inundated by 100-year flooding, for which no BFEs have been determined. This is an area to be protected from the 100-year flood by a Federal flood protection system under construction. D An area of undetermined but possible flood hazards. AR An area inundated by flooding, for which BFEs or average depths have been determined. This is an area that was previously, and will again, be protected from the 100-year flood by a Federal flood protection system whose restoration is Federally funded and underway. X500 An area inundated by 500-year flooding; an area inundated by 100-year flooding with average depths of less than 1 foot or with drainage areas less than 1 square mile; or an area protected by levees from the 100-year flooding. X An area that is determined to be outside the 100- and 500-year floodplains. 100IC An area where the 100-year flooding is contained within the channel banks and the channel is too narrow to show to scale. An arbitrary channel width of 3 meters is shown. BFEs are not shown in this area, although they may be reflected on the corresponding profile. 500IC An area where the 500-year flooding is contained within the channel banks and the channel is too narrow to show to scale. An arbitrary channel width of 3 meters is shown. FWIC An area where the floodway is contained within the channel banks and the channel is too narrow to show to scale. An arbitrary channel width of 3 meters is shown. BFEs are not shown in this area, although they may be reflected on the corresponding profile. FPQ An area designated as a "Flood Prone Area" on a map prepared by USGS and the Federal Insurance Administration. This area has been delineated based on available information on past floods. This is an area inundated by 100-year flooding for which no BFEs have been determined. FLOODWAY Channel, river or watercourse reserved for flood discharge. Multiple Codes refer to "Q3 Flood Data Specifications". COBRA Undeveloped Coastal Barrier Area. Multiple Codes refer to "Q3 Flood Data Specifications". SFHA In/Out of flood zone designation, determined from data topology. VALUES DESCRIPTION IN An area designated as within a "Special Flood Hazard Area" (or SFHA) on a FIRM. This is an area inundated by 100-year flooding for which no BFEs or velocity may have been determined. No distinctions are made between the different flood hazard zones that may be included within the SFHA. These may include Zones A, AE, AO, AH, A99, AR, V, or VE. OUT An area designated as outside a "Special Flood Hazard Area" (or SFHA) on a FIRM. This is an area inundated by 500-year flooding; an area inundated by 100-year flooding with average depths of less than 1 foot or with drainage areas less than 1 square mile; an area protected by levees from 100-year flooding; or an area that is determined to be outside the 100- and 500-year floodplains. No distinctions are made between these different conditions. These may include both shaded and unshaded areas of Zone X. ANI An area that is located within a community or county that is not mapped on any published FIRM. UNDES A body of open water, such as a pond, lake ocean, etc., located within a community's jurisdictional limits, that has no defined flood hazard. SYMBOL Polygon shade symbols for graphic output, based on polygon codes. Multiple Codes refer to "Q3 Flood Data Specifications" PANEL_TYP Type of FIRM panel represented. Multiple Codes refer to "Q3 Flood Data Specifications". ST_FIPS State FIPS code CO_FIPS County FIPS code Source: Federal Emergency Management Agency (FEMA), Atlanta Regional Commission Date: 1998