National Flood Hazard Layer - Rest Service

The National Flood Hazard Layer (NFHL) is a compilation of GIS data that comprises a nationwide digital Flood Insurance Rate Map. The GIS data and services are designed to provide the user with the ability to determine the flood zone, base flood elevation, and floodway status for a particular location. It also has information about the NFIP communities, map panels, cross sections, hydraulic structures, Coastal Barrier Resource System, and base maps such as road, stream, and public land survey data. Through flood studies, FEMA produces Flood Insurance Study Reports, FIRM Panels, and FIRM Databases. FIRM Databases that become effective are incorporated into the NFHL. Updates to the NFHL are issued through Letters of Map Revision (LOMRs) and Letters of Map Amendment (LOMAs). Continuously updated, the NFHL serves as a Digital Flood Insurance Rate Map representing the current effective flood data for those communities where maps have been digitized. NFHL data can be viewed with widely available GIS software, including freely available programs that work with GIS shapefiles. For more information on the NFHL, see the online resources referenced herein. Using base maps: The minimum horizontal positional accuracy for base map hydrographic and transportation features used with the NFHL is the NSSDA radial accuracy of 38 feet. Letter of Map Amendment (LOMA) point locations are approximate. The location of the LOMA is referenced in the legal description of the letter itself. LOMA points can be viewed in the NFHL Interactive Map on the FEMA GeoPlatform.

The National Flood Hazard Layer (NFHL) data incorporates all Flood Insurance Rate Map (FIRM) databases published by the Federal Emergency Management Agency (FEMA), and any Letters of Map Revision (LOMRs) that have been issued against those databases since their publication date. It is updated on a monthly basis. The FIRM Database is the digital, geospatial version of the flood hazard information shown on the published paper FIRMs. The FIRM 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 FIRM Database is derived from Flood Insurance Studies (FISs), previously published 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 FEMA. The NFHL is available as State or US Territory data sets. Each State or Territory data set consists of all FIRM Databases and corresponding LOMRs available on the publication date of the data set. The specification for the horizontal control of FIRM Databases is consistent with those required for mapping at a scale of 1:12,000. This file is georeferenced to the Earth's surface using the Geographic Coordinate System (GCS) and North American Datum of 1983.

The National Flood Hazard Layer (NFHL) is a geospatial database that contains current effective flood hazard data. FEMA provides the flood hazard data to support the National Flood Insurance Program. You can use the information to better understand your level of flood risk and type of flooding. The NFHL is made from effective flood maps and Letters of Map Change (LOMC) delivered to communities. New and revised data is being added continuously.  For more information National Flood Hazard Layer.

FEMA provides access to the National Flood Hazard Layer through a Web Map Service. The National Flood Hazard Layer is a computer database that contains FEMA's flood hazard map data. The data depict flood hazard information and supporting data used to develop the information. The primary hazard classifications are the 1 percent-annual-chance flood event, the 0.2 percent-annual-chance flood event, and areas of minimal flood hazard. Flood hazard and supporting data are developed using specifications for horizontal control consistent with 1:12,000-scale mapping. If you plan to display maps from the National Flood Hazard Layer with other map data for official purposes, ensure that the other information meets FEMA's standards for map accuracy. The NFHL data are from FEMA's Digital Flood Insurance Rate Map (DFIRM) databases. New data are added continually. The NFHL also contains changes to DFIRM data made by Letters of Map Revision (LOMRs). The service provides map images geo-referenced to the earth's surface using the North American Datum of 1983, Geodetic Reference System 80 coordinate system. The service also provides information that complements the National Flood Hazard Layer. In areas for which data are not available from the National Flood Hazard Layer, an older set of flood hazard data, named the "Q3" data, may be available. The service also provides information about the availability of flood data and maps, the national map panel scheme, river subbasins, and point locations for Letters of Map Amendment (LOMA) and Letters of Map Revision Based on Fill (LOMR-Fs). These complementary data are positioned less accurately than are the National Flood Hazard Layer data. The service organizes the data in layers. The layers display information at map scales appropriate for the data. Status information and river subbasins are displayed at map scales smaller than 1:300,000, regional overviews at map scales between 1:300,000 and 1:32,000, and detailed flood hazard maps at map scales of 1:32,000 and larger. The "Scalehint" item in the Capabilities file for the Web Map Service encodes the scale range for maps for a layer. Flood hazard areas identified on the Flood Insurance Rate Map are identified as a Special Flood Hazard Area (SFHA). SFHA are defined as the area that will be inundated by the flood event having a 1-percent chance of being equaled or exceeded in any given year. The 1-percent annual chance flood is also referred to as the base flood or 100-year flood. SFHAs are labeled as Zone A, Zone AO, Zone AH, Zones A1-A30, Zone AE, Zone A99, Zone AR, Zone AR/AE, Zone AR/AO, Zone AR/A1-A30, Zone AR/A, Zone V, Zone VE, and Zones V1-V30. Moderate flood hazard areas, labeled Zone B or Zone X (shaded) are also shown on the FIRM, and are the areas between the limits of the base flood and the 0.2-percent-annual-chance (or 500-year) flood. The areas of minimal flood hazard, which are the areas outside the SFHA and higher than the elevation of the 0.2-percent-annual-chance flood, are labeled Zone C or Zone X (unshaded). Flood Zone Definitions from the FEMA Flood Map Service Center. Data Download: https://www.floodmaps.fema.gov/NFHL/status.shtml

FEMA provides access to the National Flood Hazard Layer through a Web Map Service. The National Flood Hazard Layer is a computer database that contains FEMA's flood hazard map data. The data depict flood hazard information and supporting data used to develop the information. The primary hazard classifications are the 1 percent-annual-chance flood event, the 0.2 percent-annual-chance flood event, and areas of minimal flood hazard. Flood hazard and supporting data are developed using specifications for horizontal control consistent with 1:12,000-scale mapping. If you plan to display maps from the National Flood Hazard Layer with other map data for official purposes, ensure that the other information meets FEMA's standards for map accuracy. The NFHL data are from FEMA's Digital Flood Insurance Rate Map (DFIRM) databases. New data are added continually. The NFHL also contains changes to DFIRM data made by Letters of Map Revision (LOMRs). The service provides map images geo-referenced to the earth's surface using the North American Datum of 1983, Geodetic Reference System 80 coordinate system. The service also provides information that complements the National Flood Hazard Layer. In areas for which data are not available from the National Flood Hazard Layer, an older set of flood hazard data, named the "Q3" data, may be available. The service also provides information about the availability of flood data and maps, the national map panel scheme, river subbasins, and point locations for Letters of Map Amendment (LOMA) and Letters of Map Revision Based on Fill (LOMR-Fs). These complementary data are positioned less accurately than are the National Flood Hazard Layer data. The service organizes the data in layers. The layers display information at map scales appropriate for the data. Status information and river subbasins are displayed at map scales smaller than 1:300,000, regional overviews at map scales between 1:300,000 and 1:32,000, and detailed flood hazard maps at map scales of 1:32,000 and larger. The "Scalehint" item in the Capabilities file for the Web Map Service encodes the scale range for maps for a layer. Flood hazard areas identified on the Flood Insurance Rate Map are identified as a Special Flood Hazard Area (SFHA). SFHA are defined as the area that will be inundated by the flood event having a 1-percent chance of being equaled or exceeded in any given year. The 1-percent annual chance flood is also referred to as the base flood or 100-year flood. SFHAs are labeled as Zone A, Zone AO, Zone AH, Zones A1-A30, Zone AE, Zone A99, Zone AR, Zone AR/AE, Zone AR/AO, Zone AR/A1-A30, Zone AR/A, Zone V, Zone VE, and Zones V1-V30. Moderate flood hazard areas, labeled Zone B or Zone X (shaded) are also shown on the FIRM, and are the areas between the limits of the base flood and the 0.2-percent-annual-chance (or 500-year) flood. The areas of minimal flood hazard, which are the areas outside the SFHA and higher than the elevation of the 0.2-percent-annual-chance flood, are labeled Zone C or Zone X (unshaded). Flood Zone Definitions from the FEMA Flood Map Service Center. Data Download: https://www.floodmaps.fema.gov/NFHL/status.shtml

The National Flood Hazard Layer (NFHL) is a compilation of GIS data that comprises a nationwide digital Flood Insurance Rate Map. The GIS data and services are designed to provide the user with the ability to determine the flood zone, base flood elevation, and floodway status for a particular location. It also has information about the NFIP communities, map panels, cross sections, hydraulic structures, Coastal Barrier Resource System, and base maps such as road, stream, and public land survey data. Through flood studies, FEMA produces Flood Insurance Study Reports, FIRM Panels, and FIRM Databases. FIRM Databases that become effective are incorporated into the NFHL. Updates to the NFHL are issued through Letters of Map Revision (LOMRs) and Letters of Map Amendment (LOMAs). Continuously updated, the NFHL serves as a Digital Flood Insurance Rate Map representing the current effective flood data for those communities where maps have been digitized. NFHL data can be viewed with widely available GIS software, including freely available programs that work with GIS shapefiles. For more information on the NFHL, see the online resources referenced herein. Using base maps: The minimum horizontal positional accuracy for base map hydrographic and transportation features used with the NFHL is the NSSDA radial accuracy of 38 feet. Letter of Map Amendment (LOMA) point locations are approximate. The location of the LOMA is referenced in the legal description of the letter itself. LOMA points can be viewed in the NFHL Interactive Map on the FEMA GeoPlatform.