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Digital Flood Mapping Products

Requirements

This page is provided to distribute information about Federal Emergency Management Agency (FEMA) digital mapping products, with primary emphasis on the requirements for the Digital Flood Insurance Rate Map (DFIRM) and DFIRM Database. From this page, map producers (i.e., FEMA contractors, participants in the Cooperating Technical Partners (CTP) Program that have taken on map production assignments), mapping partners that are not participating in the CTP Program, and other stakeholders can access information about the FEMA requirements for DFIRM and DFIRM Database components. The information on DFIRM base map specifications, DFIRM graphic specifications, and DFIRM Database requirements on these pages is provided to support the FEMA product and process requirements detailed in FEMA's Guidelines and Specifications for Flood Hazard Mapping Partners (hereinafter referred as "the Guidelines").

Paper to Digital Transition

Beginning on or after October 1, 2009, FEMA will provide a single paper flood map and Flood Insurance Study (FIS) to each mapped community. FEMA will convert all other distribution of maps and FIS reports for digital delivery. FEMA will continue to provide free digital map products and data to Federal, State, Tribal, and local NFIP stakeholders. FEMA announced this change in the Federal Register (PDF, 43KB), Vol. 23, No. 76, issued on October 23, 2008. Read more about the digital transition.

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Digital Q3 Flood Data Product

The digital Q3 Flood Data product was an early digital mapping product developed by FEMA. FEMA created the digital Q3 Flood Data products by scanning (producing raster or grid data files) paper versions of effective FIRMs and vectorizing (converting to lines and areas) select data features into a countywide format.

The digital Q3 Flood Data product was designed to serve FEMA's needs for disaster response activities, NFIP activities, risk assessment, and floodplain management. The product was 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. These products are being replaced on a county-by-county basis by DFIRMs and DFIRM Databases.

Additional information on the Q3 Flood Data product, including a series of Frequently Asked Questions, sample Q3 Flood Data products for 10 counties, a User Guide, and product specifications, is accessible through the Product Information page on the FEMA Map Service Center Website.

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DFIRM Base Map Specifications

The FEMA base map specifications are detailed in Volume 1, Subsection 1.4.3.1 of the Guidelines. Subsection 1.4.3.1 outlines the minimum standards for base map data, including accuracy, resolution, currency, completeness, availability, restrictions on use, contents, and documentation. Additional information is provided in Appendix A, Subsection A.1.1 of the Guidelines.

Base map data supplied by communities or other non-Federal sources (e.g., State agencies, regional agencies) that meet FEMA criteria are the first choice for DFIRM production. Digital Orthophoto Quarter Quadrangles produced by the U.S. Geological Survey are the second choice and the default base map when suitable community data are not available.

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DFIRM Graphic Specifications

The specifications for the graphic elements shown on the DFIRMs are detailed in Appendix K of the Guidelines. Appendix K provides information on base map elements, flood hazard information, map legend, title block, line weights, colors, dashing, and text fonts used in producing DFIRMs. Issues such as how the DFIRMs are paneled and the specifications for the DFIRM Map Index are also addressed.

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DFIRM Database Requirements

Information about the spatial database used to store the Geographic Information System (GIS)-based attributes of the DFIRMs is provided in Appendix L of the Guidelines. Appendix L includes information on database design considerations, technical content, and metadata requirements. Appendix L also describes the tables and fields contained in the DFIRM Database.

The DFIRM Database is designed to facilitate access to, as well as collection, storage, and processing of, data developed by FEMA for the NFIP. The DFIRM Database will enable FEMA, FEMA contractors, and FEMA mapping partners to share data necessary for hydrologic and hydraulic (H&H) modeling and DFIRM production. In addition, the DFIRM Database will enable maps to be rapidly updated and revised in the future.

The use of GIS as a component of the DFIRM Database allows the mapping and engineering data elements to be linked to physical features, georeferenced, and overlaid as needed. This, in turn, allows the database to support a wide variety of existing and visionary FEMA engineering and mapping products, such as automated H&H modeling and mapping; Web-based publishing of digital map products; and direct links between base maps, work maps, H&H modeling, and mapping elements.

The DFIRM Database content will vary based on the data available and/or developed for a particular flood study/mapping project. All DFIRMs will contain certain standard features:

In addition to the elements listed above, some DFIRM Databases may contain pertinent backup engineering data needed by FEMA, FEMA contractors, and FEMA mapping partners for FEMA-contracted flood studies/mapping projects, community-initiated map revisions, or map maintenance activities. The DFIRM Database includes information needed for core NFIP functions such as insurance rating and compliance monitoring. The DFIRM Database includes sufficient data to allow users to reproduce the Flood Profiles and water–surface elevations. Additionally, the DFIRM Database stores original products and intermediate products of high value and/or wide applicability. The DFIRM Database does not include all intermediate data developed in the course of conducting the flood study/mapping project. Some of the DFIRM Database features may be stored in GIS mapping layers or related tables, but not shown on the paper DFIRM product.

The DFIRM Database specifications contain the following additional defined spatial and non-spatial data items and tables:

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Additional DFIRM Database Information

FEMA provides the following for use by FEMA contractors and other map producers:

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Sample DFIRMs

Three full-size sample DFIRMs are accessible through the FEMA Library. They include a DFIRM Map Index and two different versions of a prototype DFIRM panel. The sample DFIRM panel is presented as a black-and-white DFIRM with a vector base map and a color DFIRM with a Digital Orthophoto Quadrangle (DOQ) base map.

This prototype of Flood County, USA, is a hypothetical example of a DFIRM product. The prototype was prepared for a single FIRM panel. Normally, the DFIRM will include all the digital data for an entire community or county.

This group of single panel samples, suitable for plotting, consists of several DFIRMs. A sample Map Index, a sample black-and-white DFIRM, and a sample color DFIRM. The black-and-white DFIRM was produced using a vector base map. The color DFIRM was produced using a DOQ as the base map, and is available in 2 resolutions, 300 and 600 DPI. All community names and numbers, as well as the map numbers, are hypothetical.

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For More Information

If you have additional questions about digital mapping products or need additional assistance:

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Return to the FEMA Guidance Documents and Other Published Resources page

Last Modified: Thursday, 11-Dec-2008 11:45:52 EST