The following table gives an explanation for the flood zone designations: They were formerly mapped and depicted as Zone C. X Zone (unshaded), representing the areas on the FIRM that are located outside the limits of the 500-year flooding. They were formerly mapped and depicted as Zone B. These areas are located outside the SFHA, but are depicted on the FIRM unless map scale limitations prevent detailed mapping of this area. X Zone (shaded), representing the coastal (or riverine) floodplain areas between the 100- year flood and 0.2% annual chance (500-year) flood. These areas are usually not subdivided, and BFEs are mapped. The AO Zone is also used in riverine flood mapping.ĪH Zones, representing coastal hazard areas associated with shallow flow or ponding, with water depths of 1 to 3 feet. These SFHAs generally are located in areas of sheet flow and runoff from coastal FLOOD HAZARD ZONES 3 FEMA COASTAL FLOOD HAZARD ANALYSIS AND MAPPING GUIDELINES FOCUSED STUDY REPORTS flooding where a BFE cannot be established. Depths are mapped from 1 to 3 feet, in whole-foot increments. The AE Zones also depict the SFHA due to riverine flood sources, but instead of being subdivided into separate zones of differing BFEs with possible wave effects added, they represent the flood profile determined by hydrologic and hydraulic investigations and have no wave effects.ĪO Zones, representing coastal hazard areas that are mapped with flood depths instead of base flood elevations. The AE Zone generally extends from the landward VE zone limit to the limits of the 100-year flood from coastal sources, or until it reaches the confluence with riverine flood sources. The hazard zone is mapped with base flood elevations (BFEs) that reflect the combined influence of stillwater flood elevations, primary frontal dunes, and wave effects 3 feet or greater.ĪE Zones, also within the 100-year flood limits, are defined with BFEs that reflect the combined influence of stillwater flood elevations and wave effects less than 3 feet. They are areas subject to high velocity water including waves they are defined by the 1% annual chance (base) flood limits (also known as the 100-year flood) and wave effects 3 feet or greater. VE Zones, also known as the coastal high hazard areas. The FIRM depiction of the Special Flood Hazard Area (SFHA) for coastal hazards, as determined by detailed studies of storm surge flooding, storm-induced erosion, and wave effects, is generally subdivided into six different zones, including: The results of the coastal flood study are described in the FIS report and delineated onto a Flood Insurance Rate Map (FIRM). Hazard zone mapping is the final product of the detailed analyses of a coastal flood study process undertaken by a Mapping Partner, performed either by the study contractor (SC), map revision requester, or Cooperating Technical Partner (CTP). Current FEMA Guidance for Flood Hazard Zones
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