Frequently Asked Questions

Digital Flood Data and Mapping

What are FEMA's Digital Mapping Specifications?

FEMA has published three digital map product specifications:

  1. FEMA-37
    "Guidelines and Specifications for Study Contractors," January 1995

    The "Guidelines and Specifications for Study Contractors" provides guidance on how to prepare and submit restudies. Appendix 4, Aerial Mapping and Surveying Specification, and Appendix 7, Digital Product Delivery Specification.

  2. FIA-21
    "Standards for Digital Flood Insurance Rate Maps," October 1993

    The "Standards for Digital Flood Insurance Rate Maps" provides guidance to producers and users of FEMA's Digital Flood Insurance Rate Map data, including specifications and content.

  3. "Q3 Flood Data Specifications," Draft May 1998

    The "Q3 Flood Data Specifications" provides guidance to producers and users of FEMA's Q3 Flood Data products including specifications and content. This draft document is available in electronic format (WordPerfect 5.1 and ASCII text), on CD-ROM, or through FEMA's Internet pages.

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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.

DFIRMs
A Digital Flood Insurance Rate Map (DFIRM) includes all digital data required to create the hardcopy Flood Insurance Rate Map to FEMA FIA-21 standards and specifications (see the "Standards for Digital Flood Insurance Rate Maps"). 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 NFIP.

Q3 Flood Data
Q3 Flood Data are developed by digitizing existing hardcopy Flood Insurance Rate Maps (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 Geographic Information Systems 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.

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Is digital data available for my community? How do I obtain digital data?

Digital Flood Insurance Rate Maps (DFIRMs) have been produced for a small number of communities.

Nearly 1,300 counties now have Q3 Flood Data. Approximately 880 counties were chosen for the initial production phase to provide digital data coverage in areas of high population density or growth, significant risk (from hurricanes or other flood events), or a history of repetitive losses. Approximately 400 additional counties were produced in response to declared disasters.

A listing of the Q3 Flood Data counties may be obtained from FEMA's Map Service Center (1-800-358-9616) or by linking to their Q3 Flood Data Availability Map. The list is also published in FEMA's draft "Q3 Flood Data Users Guide".

Q3 Flood Data products are provided in a public domain data transfer format (DLG) as well as proprietary formats (ARC/INFO¨ and MapInfo¨). Internet users may download Q3 Flood Data standards and metadata files by accessing FEMA's Map Service Center.

CD-ROMs with the Q3 Flood Data files may be ordered from FEMA's Map Service Center at the following address:

Map Service Center
P.O. Box 1038
Jessup, Maryland 20794-1038
Telephone: (800) 358-9616
Fax: (800) 358-9620

To order products by phone or fax, call the Map Service Center toll free Monday through Friday from 8:00 a.m. to 8:00 p.m. (eastern time). Additional information, including cost is available on FEMA's Map Service Center site.

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How can I get a list of available GIS and desktop mapping software?

Software retailers should be able to recommend PC-based desktop mapping software. Larger workstation Geographic Information Systems (GIS) software is a more specialized market and is usually sold directly by the manufacturer or through consultants. GIS or survey trade publications have advertisements for most of the popular packages.

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Are the Flood Insurance Rate Map-Digital Line Graphs (FIRM-DLG) still available?

No. The digital Q3 Flood Data replaces the Flood Insurance Rate Map-Digital Line Graphs data product.

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Are the digital Q3 Flood Data compatible with other digital Flood Insurance Rate Map data products?

Yes. FEMA intends to produce consistent, quality assured data for use in floodplain management, hazards analysis, and risk assessment.

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When will Digital Flood Insurance Rate Map-Digital Line Graph (DFIRM-DLG) data be available in my area?

The Digital Flood Insurance Rate Map-Digital Line Graph (DFIRM-DLG) requires a more rigorous development cycle, including a community review of the hardcopy DFIRM prior to release. Therefore, it is difficult to estimate when an individual area of the country will be produced and distributed.

 

Need additional help?

FEMA Map Assistance Center
Call 1-877-FEMA-MAP
Email a Map Specialist

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Last Modified: Friday, 12-Oct-2007 11:29:10 EDT

Fast Facts

Additional FAQ Topics

Digital Flood Data and Mapping
General Information
Flood Insurance
Flood Map Policy and Program
Flood Map Process
Flood Revision
Flood Study Data
Frequently Used Terms
Q3 Flood Data