What types of digital flood map data are available from FEMA?


FEMA prepares digital data in two product specifications: Digital Flood Insurance Rate Maps (DFIRMs) and Q3 Flood Data.


A DFIRM includes all digital data required to create the hardcopy Flood Insurance Rate Map (FIRM) (see FIA-21, "Standards for Digital Flood Insurance Rate Maps" October 1993). It includes base map information, graphics, text, shading, and other geographic and graphic data. DFIRM specifications are consistent with those required for mapping at a scale of 1:24,000, or larger.

DFIRMs generally are produced in a countywide format. They include information from the unincorporated areas of a county and all the incorporated communities within that county.

Hardcopy maps printed from the DFIRMs are reviewed and approved by each community. They are the official basis for implementing the regulations and requirements of the National Flood Insurance Program.

Q3 Flood Data

Q3 Flood Data are developed by digitizing existing hardcopy FIRMs to create a thematic overlay of flood risks. This product is generally produced in a countywide format. Q3 Flood Data files contain only certain features from the existing hardcopy maps.

Q3 Flood Data do not replace the existing hardcopy maps. They are designed to support planning activities, some Community Rating System (CRS) activities, insurance marketing, mortgage portfolio review, FEMA's Response and Recovery activities, and to assist in floodplain management activities at a local level. Base Flood Elevations are not included so its use is limited.

Q3 Flood Data do not include a base map, are not used to produce a new version of the hardcopy FIRM, and are not reviewed by communities. They are for use with desk-top mapping and GIS technology.

FEMA and ESRI signed a Project Impact National Partnership agreement making flood hazard maps available for all areas where FEMA has prepared Q3 flood data.

Last Updated: 2007-01-05 11:38:55.0

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