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. NFHL digital data covers over 90 percent of the U.S. population. New and revised data is being added continuously. If you need information for areas not covered by the NFHL data, there may be other FEMA products which provide coverage for those areas.In the NFHL Viewer, you can use the address search or map navigation to locate an area of interest and the NFHL Print Tool to download and print a full Flood Insurance Rate Map (FIRM) or FIRMette (a smaller, printable version of a FIRM) where modernized data exists. Technical GIS users can also utilize a series of dedicated GIS web services that allow the NFHL database to be incorporated into websites and GIS applications. For more information on available services, go to the NFHL GIS Services User Guide.You can also use the address search on the FEMA Flood Map Service Center (MSC) to view the NFHL data or download a FIRMette. Using the “Search All Products” on the MSC, you can download the NFHL data for a County or State in a GIS file format. This data can be used in most GIS applications to perform spatial analyses and for integration into custom maps and reports. To do so, you will need GIS or mapping software that can read data in shapefile format.FEMA also offers a download of a KMZ (keyhole markup file zipped) file, which overlays the data in Google Earth™. For more information on using the data in Google Earth™, please see Using the National Flood Hazard Layer Web Map Service (WMS) in Google Earth™.

FEMA provides access to the National Flood Hazards Layer (NFHL) through web mapping services. The maps depict effective flood hazard information and supporting data. The primary flood hazard classification is indicated in the Flood Hazard Zones layer.The NFHL layers include:Flood hazard zones and labelsRiver Miles MarkersCross-sections and coastal transects and their labelsLetter of Map Revision (LOMR) boundaries and case numbersFlood Insurance Rate Map (FIRM) boundaries, labels and effective datesCoastal Barrier Resources System (CBRS) and Otherwise Protected Area (OPA) unitsCommunity boundaries and namesLeveesHydraulic and flood control structuresProfile and coastal transect baselinesLimit of Moderate Wave Action(LiMWA)Not all effective Flood Insurance Rate Maps (FIRM) have GIS data available. To view a list of available county and single-jurisdiction flood study data in GIS format and check the status of the NFHL GIS services, please visit the NFHL Status Page.Preliminary & Pending National Flood Hazard LayersThe Preliminary and Pending NFHL dataset represents the current pre-effective flood data for the country. These layers are updated as new preliminary and pending data becomes available, and data is removed from these layers as it becomes effective.For more information, please visit FEMA's website.To download map panels or GIS Data, go to: NFHL on FEMA GeoPlatform.Preliminary & Pending DataPreliminary data are for review and guidance purposes only. By viewing preliminary data and maps, the user acknowledges that the information provided is preliminary and subject to change. Preliminary data are not final and are presented in this national layer as the best information available at this time. Additionally, preliminary data cannot be used to rate flood insurance policies or enforce the Federal mandatory purchase requirement. FEMA will remove preliminary data once pending data are available.Pending data are for early awareness of upcoming changes to regulatory flood map information. Until the data becomes effective, when it will appear in FEMA's National Flood Hazard Layer (NFHL), the data should not be used to rate flood insurance policies or enforce the Federal mandatory purchase requirement. FEMA will remove pending data once effective data are available.To better understand Preliminary data please see the View Your Community's Preliminary Flood Hazard Data webpage.FEMA GeoPlatformFEMA's GIS flood map services are available through FEMAs GeoPlatform, an ArcGIS Online portal containing a variety of FEMA-related data.To view the NFHL on the FEMA GeoPlatform go to NFHL on FEMA GeoPlatform.To view the Preliminary and Pending national layers on the FEMA Geoplatform go to FEMA's Preliminary & Pending National Flood Hazard Layer.Technical InformationFlood 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 NFHL with other map data for official purposes, ensure that the other information meets FEMA’s standards for map accuracy.The minimum horizontal positional accuracy for base map hydrographic and transportation features used with the NFHL is the NSSDA radial accuracy of 38 feet. United States Geological Survey (USGS) imagery and map services that meet this standard can be found by visiting the Knowledge Sharing Site (KSS) for Base Map Standards (420). Other base map standards can be found at https://riskmapportal.msc.fema.gov/kss/MapChanges/default.aspx. You will need a username and password to access this information.The NFHL data are from FEMA’s FIRM databases. New data are added continually. The NFHL also contains map changes to FIRM data made by LOMRs.The NFHL is stored in North American Datum of 1983, Geodetic Reference System 80 coordinate system, though many of the NFHL GIS web services support the Web Mercator Sphere projection commonly used in web mapping applications.Organization & DisplayThe NFHL is organized into many data layers. The layers display information at map scales appropriate for the data. A layer indicating the availability of NFHL data is displayed at map scales smaller than 1:250,000, regional overviews at map scales between 1:250,000 and 1:50,000, and detailed flood hazard maps at map scales of 1:50,000 and larger. The "Scalehint" item in the Capabilities file for the Web Map Service encodes the scale range for a layer.In addition, there are non-NFHL datasets provided in the GIS web services, such as information about the availability of flood data and maps, the national map panel scheme, and point locations for LOMA and LOMR-Fs. The LOMA are positioned less accurately than are the NFHL data.Layers in the public NFHL GIS services:Use the numbers shown below when referencing layers by number.0. NFHL Availability1. LOMRs2. LOMAs3. FIRM Panels4. Base Index5. PLSS6. Toplogical Low Confidence Areas7. River Mile Markers8. Datum Conversion Points9. Coastal Gages10. Gages11. Nodes12. High Water Marks13. Station Start Points14. Cross-Sections15. Coastal Transects16. Base Flood Elevations17. Profile Baselines18. Transect Baselines19. Limit of Moderate Wave Action20. Water Lines21. Coastal Barrier Resources System Area22. Political Jurisdictions23. Levees24. General Structures25. Primary Frontal Dunes26. Hydrologic Reaches27. Flood Hazard Boundaries28. Flood Hazard Zones29. Submittal Information30. Alluvial Fans31. Subbasins32. Water Areas

2017 FEMA Flood Zone for Macon-Bibb County. Through FEMA's flood hazard mapping program, Risk Mapping, Assessment and Planning (MAP), FEMA identifies flood hazards, assesses flood risks and partners with states and communities to provide accurate flood hazard and risk data to guide them to mitigation actions. Flood hazard mapping is an important part of the National Flood Insurance Program (NFIP), as it is the basis of the NFIP regulations and flood insurance requirements. FEMA maintains and updates data through Flood Insurance Rate Maps (FIRMs) and risk assessments. FIRMs include statistical information such as data for river flow, storm tides, hydrologic/hydraulic analyses and rainfall and topographic surveys. For more information regarding FEMA's flood hazard mapping program visit https://www.fema.gov/national-flood-insurance-program-flood-hazard-mapping.

A collection of citywide Geographic Information System (GIS) layers that show areas of potential flooding scenarios under varying sea level rise conditions. Please see the New York City Stormwater Resiliency Plan for more information about the methodology applied to develop the maps. Please direct questions or comments to StormwaterResiliency@cityhall.nyc.gov. This collection contains the following NYC Stormwater Flood Maps: NYC Stormwater Flood Map - Extreme Flood (3.66 inches/hr) with 2080 Sea Level Rise NYC Stormwater Flood Map - Moderate Flood (2.13 inches/hr) with 2050 Sea Level Rise NYC Stormwater Flood Map - Moderate Flood (2.13 inches/hr) with Current Sea Levels NYC Stormwater Flood Map - Limited Flood (1.77 inches/hr) with Current Sea Levels https://www1.nyc.gov/assets/orr/pdf/publications/stormwater-resiliency-plan.pdf Source Data: http://nyc.gov/stormwater-map

This feature layer was derived from the FEMA National Flood Hazard Layer (NFHL), available from the FEMA National Mapping Information Platform. This feature set includes the following layers: Zone A-The flood insurance rate zone that corresponds to the 100-year floodplains that are determined in the FIS by approximate methods. Because detailed hydraulic analyses are not performed for such areas, no base flood elevations or depths are shown within this zone.Zone AE-The flood insurance rate zone that corresponds to the 100-year floodplains that are determined in the FIS by detailed methods. In most instances, whole-foot base flood elevations derived from the detailed hydraulic analyses are shown at selected intervals within this zone.Zone AH-The flood insurance rate zone that corresponds to the 100-year shallow flooding (usually areas of ponding) where average depths are between 1 and 3 feet. Whole-foot base flood elevations are derived from detailed hydraulic analyses are shown at selected intervals within this zone.Zone X-The flood insurance rate zone that corresponds to areas outside the 500-year floodplain, areas within the 500- year floodplain, and areas of 100-year flooding where average depths are less than 1 foot, areas of 100-year flooding where the contributing drainage area is less than 1 square mile, and areas protected from 100-year flood by levees. No base flood elevations or depths are shown within this zone.Regulatory Floodway-A floodplain management tool that is the regulatory area defined as the channel of a stream, plus any adjacent floodplain areas, that must be kept free of encroachment so that the base flood discharge can be conveyed without increasing the BFEs more than a specified amount. The regulatory floodway is not an insurance rating factor. For more information on FEMA Flood Zone definitions, visit the FEMA National Mapping Information Platform.

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 scaleof 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.

Digital flood-inundation maps for an approximate 2.5-mile (mi) reach of the Clear Fork Mohican River that extends approximately from State Route 97 to the downstream corporate boundary for Bellville, Ohio, were created by the U.S. Geological Survey (USGS) in cooperation with the Muskingum Watershed Conservancy District. The flood-inundation maps show estimates of the areal extent and depth of flooding corresponding to selected water levels (stages) at the USGS streamgage on the Clear Fork Mohican River at Bellville (station number 03131982). The maps can be accessed through the USGS Flood Inundation Mapping Science Web site at http://water.usgs.gov/osw/flood_inundation/. Near-real-time stages at this streamgage can be obtained from the USGS National Water Information System at http://waterdata.usgs.gov/oh/nwis/uv/?site_no=03131982 or the National Weather Service (NWS) Advanced Hydrologic Prediction Service (AHPS) at http://water.weather.gov/ahps2/hydrograph.php?wfo=cle&gage= ...

North Carolina Effective Flood zones: In 2000, the Federal Emergency Management Agency (FEMA) designated North Carolina a Cooperating Technical Partner State, formalizing an agreement between FEMA and the State to modernize flood maps. This partnership resulted in creation of the North Carolina Floodplain Mapping Program (NCFMP). As a CTS, the State assumed primary ownership and responsibility of the Flood Insurance Rate Maps (FIRMs) for all North Carolina communities as part of the National Flood Insurance Program (NFIP). This project includes conducting flood hazard analyses and producing updated, Digital Flood Insurance Rate Maps (DFIRMs). Floodplain management is a process that aims to achieve reduced losses due to flooding. It takes on many forms, but is realized through a series of federal, state, and local programs and regulations, in concert with industry practice, to identify flood risk, implement methods to protect man-made development from flooding, and protect the natural and beneficial functions of floodplains. FIRMs are the primary tool for state and local governments to mitigate areas of flooding. Individual county databases can be downloaded from https://fris.nc.gov Updated Jan 17th, 2025.

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 State Plane coordinate system. The specifications for the horizontal control of DFIRM data files are consistent with those required for mapping at a scale of 1:12,000.

This data consists of a composite inundation hazards layer for counties from TX to ME, which have a flood exposure snapshot. The dataset was developed from a union of FEMA flood hazard, USACE hurricane evacuation study, NOAA sea level rise of 3-ft above MHHW, and NOAA Shallow Coastal flooding georeferenced digital data. The source and date have been preserved for each source dataset in the attribution. A unique identifier for each hazard, a total number of hazards and hazard description list in the attribution provide coastal risk exposure for each polygon

This layer is sourced from maps.coast.noaa.gov.

This map service presents spatial information developed as part of the National Oceanic and Atmospheric Administration (NOAA) Office for Coastal Management’s Coastal Flood Exposure Mapper. The purpose of the online mapping tool is to provide coastal managers, planners, and stakeholders a preliminary look at exposures to coastal flooding hazards. The Mapper is a screening-level tool that uses nationally consistent data sets and analyses. Data and maps provided can be used at several scales to help communities initiate resilience planning efforts. Currently the extent of the Coastal Flood Exposure Mapper covers U.S. coastal areas along the Gulf of Mexico and Atlantic Ocean. NOAA provides the information “as-is” and shall incur no responsibility or liability as to the completeness or accuracy of this information. NOAA assumes no responsibility arising from the use of this information. For additional information, please contact the NOAA Office for Coastal Management (coastal.info@noaa.gov).

© NOAA Office for Coastal Management

Flood zones are geographic areas that FEMA has defined according to varying levels of flood risk. Each Zone reflects the severity or type of flooding in the area. These zones are depicted on a community FEMA Flood Insurance Rate Map (FIRM) or Flood Hazard Boundary Map. For more information go to: U.S. Department of Homeland Security, FEMA Map Service Center at http://www.msc.fema.gov Version 2.0

The Digital Flood Insurance Rate Map (DFIRM) Database depicts flood risk Information And supporting data used to develop the risk data. The primary risk; classificatons 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 1:12,000.

Understanding the relationship between flood inundation and floodplains is critical for ecosystem and community health and well-being, as well as targeting floodplain and riparian restoration. Many communities in the United States, particularly those in rural areas, lack inundation maps due to the high cost of flood modeling. Only 60% of the conterminous United States has Flood Insurance Rate Maps (FIRMs) through the U.S. Federal Emergency Management Agency (FEMA). This EnviroAtlas dataset provides an estimate of the 100-year floodplain for the conterminous United States at 30-meter resolution to fill the gaps in the FIRM. The model hit rate for the CONUS was 0.79 compared to the FIRM, indicating that the model captured 79% of the 100-year floodplain identified by FEMA. This product provides complete coverage for the CONUS by identifying floodplains in areas without FIRMs, while also identifying floodplains in tributaries sometimes excluded by FEMA. This dataset was produced by the US EPA to support research and online mapping activities related to EnviroAtlas. EnviroAtlas (https://www.epa.gov/enviroatlas) allows the user to interact with a web-based, easy-to-use, mapping application to view and analyze multiple ecosystem services for the contiguous United States. The dataset is available as downloadable data (https://edg.epa.gov/data/Public/ORD/EnviroAtlas) or as an EnviroAtlas map service. Additional descriptive information about each attribute in this dataset can be found in its associated EnviroAtlas Fact Sheet (https://www.epa.gov/enviroatlas/enviroatlas-fact-sheets) or journal article (https://doi.org/10.1016/j.scitotenv.2018.07.353). This dataset is useful for evaluating the potential value of ecosystem services provided by floodplains. The overall goal of EnviroAtlas is to employ and develop the best available science to map indicators of ecosystem services production, demand, and drivers for the nation. These data are not meant to replace or supplement FEMA Flood Insurance Rate Maps. This dataset is associated with the following publication: Woznicki, S., J. Baynes, S. Panlasigui, M. Mehaffey, and A. Neale. Development of a spatially complete floodplain map of the conterminous United States using random forest. SCIENCE OF THE TOTAL ENVIRONMENT. Elsevier BV, AMSTERDAM, NETHERLANDS, 647: 942-953, (2018).

description: 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 Lambert Conformal Conic projection and the Arkansas State Plane NAD83 North Zone coordinate system. The specifications for the horizontal control of Base Map data files are consistent with those required for mapping at a scale of 1:12,000 and 1:24,000.; abstract: 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 Lambert Conformal Conic projection and the Arkansas State Plane NAD83 North Zone coordinate system. The specifications for the horizontal control of Base Map data files are consistent with those required for mapping at a scale of 1:12,000 and 1:24,000.

Heavy rainfall occurred across Louisiana during March 8-19, 2016, as a result of a massive, slow-moving southward dip in the jet stream, which moved eastward across Mexico, then neared the Gulf Coast, funneling deep tropical moisture into parts of the Gulf States and the Mississippi River Valley. The storm caused major flooding in north-central and southeastern Louisiana. Digital flood-inundation maps for a 4.3-mile reach within the community of Monroe near Black Bayou in Ouachita Parish, LA was created by the U.S. Geological Survey (USGS) in cooperation with Federal Emergency Management Agency (FEMA) to support response and recovery operations following a March 8-19, 2016 flood event. The inundation maps depict estimates of the areal extent and depth of flooding corresponding to 4 high-water marks (HWM) identified and surveyed by the USGS following the flood event.

The Digital Flood Insurance Rate Map (DFIRM) Database depicts flood risk Information And supporting data used to develop the risk data. The primary risk; classificatons 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 1:12,000.

Heavy rainfall occurred across Louisiana during March 8-19, 2016, as a result of a massive, slow-moving southward dip in the jet stream, which moved eastward across Mexico, then neared the Gulf Coast, funneling deep tropical moisture into parts of the Gulf States and the Mississippi River Valley. The storm caused major flooding in north-central and southeastern Louisiana. Digital flood-inundation maps for a 3.8-mile reach west of the community of Natchitoches near Sibley Lake in Natchitoches Parish, LA was created by the U.S. Geological Survey (USGS) in cooperation with Federal Emergency Management Agency (FEMA) to support response and recovery operations following a March 8-19, 2016 flood event. The inundation maps depict estimates of the areal extent and depth of flooding corresponding to 4 high-water marks (HWM) identified and surveyed by the USGS following the flood event.

Normally, any FIRM that has associated flood profiles has cross sections. The S_XS table contains information about cross section lines. These lines usually represent the locations of channel surveys performed for input into the hydraulic model used to calculate flood elevations. Sometimes cross sections are interpolated between surveyed cross sections using high accuracy elevation data. Depending on the zone designation (Zone AE, Zone A, etc.), these locations may be shown on Flood Profiles in the FIS report and can be used to cross reference the Flood Profiles to the planimetric depiction of the flood hazards. This information is used in the Floodway Data Tables in the FIS report, as well as on the FIRM panels.

This layer is a component of Region Preliminary Data.