Climate & Health – Flood Vulnerability

Source Description

The National Flood Hazard Layer (NFHL) is a digital database that contains flood hazard mapping data from FEMA’s National Flood Insurance Program (NFIP). This map data is derived from Flood Insurance Rate Map (FIRM) databases and Letters of Map Revision (LOMRs).The NFHL is for community officials and members looking to view effective regulatory flood hazard information in a Geographic Information Systems (GIS) application.

Screenshot of the National Flood Hazard Layer (NFHL) for Downtown Boston. The NFHL image displays the different flood hazard areas (shown in the blue and yellow shaded areas), as well as Flood Insurance Rate Map (FIRM) panels and Letter of Map Amendments (LOMAs) for the geographic area.

The NFHL provides users with the ability to determine the flood zone, base flood elevation and floodway status for a particular geographic location. It also has National Flood Insurance Program (NFIP) community information, map panel information, cross section and hydraulic structure information, Coastal Barrier Resource System information (if applicable) and base map information, such as road, stream and public land survey data. A full list of the layers available in the NFHL may be found in the NFHL GIS Services User Guide.

The NFHL dataset represents the current effective flood risk data for those parts of the country where maps have been modernized. It is a compilation of effective Flood Insurance Rate Map (FIRM) databases and Letters of Map Revision (LOMR). The NFHL is updated as new data reaches its designated effective date and becomes valid for regulatory use under the NFIP.