Development regulations need a thorough and accurate mapping of Special Flood Hazard Areas (SFHAs) and related flood hazard data. Most communities in the National Flood Insurance Program (NFIP) have a Flood Insurance Rate Map (FIRM) provided by the Federal Emergency Management Agency (FEMA).
Three types of areas are shown on FIRMs:
- Areas with detailed mapping of the SFHA (shown as AE, VE, etc., Zones)
- Areas with approximate mapping of the SFHA (shown as A, V, etc. Zones)
- Areas shown as being outside the SFHA (depicted as B, C, D and X Zones)
The difference between detailed mapping and approximate mapping for FIRMs is that detailed maps include the base flood elevations needed to set minimum protection levels for new buildings. In most riverine situations, NFIP detailed mapping also includes floodway delineations. In coastal areas, detailed mapping may include delineation of a velocity or VE Zone.
Flood hazard areas that were not mapped as SFHAs during the preparation of the community’s FIRM (i.e., B, C, D, and X Zones) have no floodplain management requirements under the NFIP.