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<br />Guidelines and Specifications for Flood Hazard Mapping Partners [April 2003] <br /> <br />. The amount of existing or anticipated development potentially affected by tht: flooding <br />source; <br /> <br />. The flood insurance risk zone designation of the subject area on the effective FIRM; <br /> <br />. The number of actual flooding events that confirm or contradict the mapped flood <br />hazards on the effective FIRM; and <br /> <br />. The cost of performing the Flood Map Project. <br /> <br />Tables 1-1 and 1-2 provide guidance for selecting the most appropriate method for riverine and <br />coastal environs, respectively, based on the first three criteria listed above. The selected methods <br />may then be changed by the FEMA Lead in coordination with the Project Management Team, <br />based on the cost. For example, a flooding source proposed for a detailed study may be changed <br />to redelineation of floodplain boundaries using updated topographic data if available ftmding so <br />dictates. <br /> <br />The following subsections briefly describe each of the methods listed in Tables 1-1 and 1-2. <br /> <br />Use Effective Information-Riverine <br /> <br />This is the least expcnsivc mcthod of updating data for riverine areas. No new-analyses or <br />floodplain mapping are required; rather, the effective NFIP data are used "as-is." Mapped flood <br />hazard areas on the effective NFIP map that are not being updated through a de:tailed or <br />approximate study or redelineation are "carried over" to the updated FIRM, For Flood Map <br />Projects that entail converting a manually produced FIRM to a digital FIRM (i.e., digital <br />conversion), the effective information must be digitized and fitted to the selected base map. In <br />some instances, FEMA or the community may identify the need to create a digital FIRM for a <br />community or county where no study is ongoing. This may be to advance FEMA's goal of <br />converting its entire flood map inventory to a digital format; to use a more accurate, up-to-date <br />base map, or to provide the community with the increased capability of GIS-based digital FIRM <br />data. <br /> <br />Use Effective Information-Coastal <br /> <br />This is the least expensive method of updating data for coastal areas. No new analyses or <br />floodplain mapping are required; rather, the effective NFIP data are used "as-is." Mapped flood <br />hazard areas on the effective NFIP map that are not being updated through a coastal re-analysis <br />or redelineation are "carried over" to the updated FIR1vl. For Flood Map Projects that entail <br />converting a manually produced FIRM to a digital FIRM, the effective information must be <br />digitized and fitted to the selected base map. <br /> <br />1-35 <br /> <br />Section ],3 <br />