Levees and the National Flood Insurance Program: Improving Policies and Practices (2013)
Chapter: Appendix E: Flood Zone Designations
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Suggested Citation:
"Appendix E: Flood Zone Designations." National Research Council. 2013. Levees and the National Flood Insurance Program: Improving Policies and Practices. Washington, DC: The National Academies Press.
doi: 10.17226/18309.
Moderate to Low Risk Areas
In communities that participate in the NFIP, flood insurance is available to all property owners and renters in these zones:
| ZONE | DESCRIPTION |
| B and X (shaded) |
Area of moderate flood hazard, usually the area between the limits of the 100-year and 500-year floods. Are also used to designate base floodplains of lesser hazards, such as areas protected by levees from 100-year flood, or shallow flooding areas with average depths of less than one foot or drainage areas less than 1 square mile. |
| C and X (unshaded) |
Area of minimal flood hazard, usually depicted on FIRMs as above the 500-year flood level. |
High Risk Areas
In communities that participate in the NFIP, mandatory flood insurance purchase requirements apply to all of these zones:
| ZONE | DESCRIPTION |
| A | Areas with a 1% annual chance of flooding and a 26% chance of flooding over the life of a 30-year mortgage. Because detailed analyses are not performed for such areas; no depths or base flood elevations are shown within these zones. |
| AE | The base floodplain where base flood elevations are provided. AE Zones are now used on new format FIRMs instead of A1-A30 Zones. |
| A1-30 | hese are known as numbered A Zones (e.g., A7 or A14). This is the base floodplain where the FIRM shows a BFE (old format). |
| AH | reas with a 1% annual chance of shallow flooding, usually in the form of a pond, with an average depth ranging from 1 to 3 feet. These areas have a 26% chance of flooding over the life of a 30-year mortgage. Base flood elevations derived from detailed analyses are shown at selected intervals within these zones. |
| AO | River or stream flood hazard areas, and areas with a 1% or greater chance of shallow flooding each year, usually in the form of sheet flow, with an average depth ranging from 1 to 3 feet. These areas have a 26% chance of flooding over the life of a 30-year mortgage. Average flood depths derived from detailed analyses are shown within these zones. |
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SOURCE: FEMA’s Map Service Center, available online at https://msc.fema.gov/webapp/wcs/stores/servlet/info?storeId=10001&catalogId=10001&langId=-1&content=floodZones&title=FEMA%2520Flood%2520Zone%2520Designations [accessed August 6, 2012].
Suggested Citation:
"Appendix E: Flood Zone Designations." National Research Council. 2013. Levees and the National Flood Insurance Program: Improving Policies and Practices. Washington, DC: The National Academies Press.
doi: 10.17226/18309.
| AR | Areas with a temporarily increased flood risk due to the building or restoration of a flood control system (such as a levee or a dam). Mandatory flood insurance purchase requirements will apply, but rates will not exceed the rates for unnumbered A zones if the structure is built or restored in compliance with Zone AR floodplain management regulations. |
| A99 | Areas with a 1% annual chance of flooding that will be protected by a Federal flood control system where construction has reached specified legal requirements. No depths or base flood elevations are shown within these zones. |
High Risk - Coastal Areas
In communities that participate in the NFIP, mandatory flood insurance purchase requirements apply to all of these zones:
| ZONE | DESCRIPTION |
| V | Coastal areas with a 1% or greater chance of flooding and an additional hazard associated with storm waves. These areas have a 26% chance of flooding over the life of a 30-year mortgage. No base flood elevations are shown within these zones. |
| VE, V1 - 30 | Coastal areas with a 1% or greater chance of flooding and an additional hazard associated with storm waves. These areas have a 26% chance of flooding over the life of a 30-year mortgage. Base flood elevations derived from detailed analyses are shown at selected intervals within these zones. |
Undetermined Risk Areas
| ZONE | DESCRIPTION |
| D | Areas with possible but undetermined flood hazards. No flood hazard analysis has been conducted. Flood insurance rates are commensurate with the uncertainty of the flood risk. |
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