Flood Zones

Definitions of FEMA Flood Zones


About Flood Zones


Flood zones are geographic areas that FEMA has defined according to varying levels of flood risk and type of flooding. These zones are depicted on the published Flood Insurance Rate Map (FIRM).
Coastal Floodzones
Special Flood Hazard Areas (SFHA) - High Risk
Special Flood Hazard Areas represent the area subject to inundation by 1% annual chance flood. Structures located within the SFHA have a 26% chance of flooding during the life of a standard 30-year mortgage. Federal floodplain management regulations and mandatory flood insurance purchase requirements apply in these zones.

AE - Areas subject to inundation by the 1% annual chance flood event determined by detailed methods. Base Flood Elevations (BFEs) are shown by the number next to the zone. Federal floodplain management regulations and mandatory flood insurance purchase requirements apply in these zones.
Coastal High Hazard Areas (CHHA) - High Risk
Coastal High Hazard Areas (CHHA) represent the area subject to inundation by 1% annual chance flood, extending from offshore to the inland limit of a primary frontal dune along an open coast and any other area subject to high velocity wave action from storms or seismic sources. Structures located within the CHHA have a 26-percent chance of flooding during the life of a standard 30-year mortgage. Federal floodplain management regulations and mandatory purchase requirements apply in these zones.

VE - Areas along coasts subject to inundation by the 1-percent-annual-chance flood event with additional hazards due to storm-induced velocity wave action. BFEs derived from detailed hydraulic coastal analyses are shown by the number next to the zone. Federal floodplain management regulations and mandatory purchase requirements apply in these zones.
LiMWA
Some areas also have a Limit of Moderate Wave Action (LiMWA) shown on the FIRM. The LiMWA is the location where the 1% annual chance wave height equals 1.5 feet. FEMA began showing the LiMWA on Flood Insurance Rate Maps to communicate the higher risk that exists in the area because the 1.5 foot breaking wave in the LiMWA zone can potentially cause foundation failure.

Non-Special Flood Hazard Area (NSFHA) - Moderate and Minimal Risk Areas
Areas of moderate or minimal hazard are studied based upon the principal source of flood in the area. However, buildings in these zones could be flooded by severe, concentrated rainfall coupled with inadequate local drainage systems. Local stormwater drainage systems are not normally considered in a community's flood insurance study. The failure of a local drainage system can create areas of high flood risk within these zones. Flood insurance is available, but is not required by regulation in these zones. Nearly 25% of all flood claims filed are for structures located within these zones.
  • X (Shaded) (X500) - Moderate risk areas within the 0.2%-annual-chance floodplain. No BFEs or base flood depths are shown within these zones.
  • X (Unshaded) - Minimal risk areas outside the 1% and 0.2%-annual-chance floodplains. No BFEs or base flood depths are shown within these zones.
View a video animation of the flood zones and the LiMWA.