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<br />Guidelines and Specifications/or Flood Hazard Mapping Partners [April 2003] <br /> <br />. It may be possible to supplement existing cross-section and structural data with additional <br />and/or updated cross sections at selected locations. <br /> <br />The topographic data and the base map data used for the FIRM must be compatible. Like <br />features in both data sources must align. If suitable existing topographic data are not available, it <br />will be necessary to develop new topographic and/or survey data. Appendix A provides the <br />requirements for developing new topographic data and performing cross-section and structure <br />surveys. <br /> <br />Makina Map Product Decisions <br /> <br />FEMA prefers to produce all new and updated FIRMs in digital fomlat. In some rare instances, <br />it may be cost-prohibitive to convert a manually produced FIRM to digital format. In such cases, <br />the FEMA Lead in coordination with the Project Management Team, may decide to produce the <br />updated FIRM using manual cartographic methods or create a "partial digital" FIRM whereby <br />only the FIRM panels affected by new or updated flood data are produced digitally, leaving the <br />other panels unrevised. The first decision, therefore, is to decide whether to produce an entire <br />FIRM digitally, produce part of the FIRM digitally, or produce the FIRM manually. <br /> <br />Base Map <br /> <br />tor t lood Map Projects that WIll result III the production of a digital FIRM suitable digital base <br />map must be available to compile the results of the project. This is critical because of the <br />expense involved in acquiring a suitable base map if none is available and because FEMA's <br />primary mission does not include the production of base cartographic data. Lack of a suitable <br />base map will likely prevent the publication of the re:vised flood data. The Available Data <br />Inventory template provided in Appendix I, Subsection 1.1.6 of these Guidelines shall be used to <br />summarize existing base map data that may be available to the Project Team. <br /> <br />If the FIRM will be produced digitally, a community-supplied base map that meets FEMA <br />criteria is the first choice for base map. USGS Digital Orthophoto Quadrangles (DOQs) are the <br />second choice and the default base map if suitable community data are not available. If neither <br />suitable community base map data nor USGS DOQs are available for a FIRM scheduled to be <br />produced digitally, the FEMA lead shall provide the community with information on base map <br />sources, including information on partnering with the USGS to initiate DOQ production for that <br />community. DOQ production normally takes 12 to 14 months, so coordination with USGS shall <br />be initiated with that time frame and the new digital FIRM production schedule in mind. <br /> <br />FEMA criteria for base maps are discussed in Section 1.4. Detailed information on FEMA base <br />map standards are provided in Subsection 1.4.3.1. <br /> <br />Map Format <br /> <br />FIRMs may be prepared in the FEMA Community-Based (i.e., single-jurisdiction) or <br />Countywide Format. These formats are described in Appendix K of these Guidelines. FEMA <br />prefers the Countywide Format. In some instances, such as when it will be cost-prohi.bitive to <br />produce a Countywide FIRM (e.g., only a relatively small portion of the county is affected by <br />new flood data, or when a suitable county base map is not available), the FEMA Lead, in <br /> <br />1-41 <br /> <br />Section ],3 <br />