What do the different flood zones mean? Flood Zone Designations

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The following table gives an explanation for the flood zone designations:

BFE = Base Flood Zone Elevation

SFHA = Land areas that are at high risk for flooding are called Special Flood Hazard Areas (SFHAs), or floodplains. These areas are indicated on Flood Insurance Rate Maps (FIRMs)

Zone

Zone Name

Description

100 Area in SFHA This is an area inundated by 100-year flooding for which BFEs or velocity may have been determined. No distinctions are made between the different flood hazard zones that may be included within the SFHA.
100IC 100-year Flood Discharge Contained in Channel An area where the 100-year flooding is contained within the channel banks and the channel is too narrow to show to scale. An arbitrary channel width of 3 meters is shown.
A Zone A An area inundated by 100 year flooding, for which no BFEs have been established.
A99 Zone A99 An area inundated by 100-year flooding, for which no BFEs have been determined. This is an area to be protected from the 100-year flood by a Federal flood protection system under construction.
AE Zone AE An area inundated by 100-year flooding, for which BFEs have been determined.
AH Zone AH An area inundated by 100-year flooding (usually an area of ponding), for which BFEs have been determined; flood depths range from 1 to 3 feet.
ANI Area Not Included An area that is located within a community or county that is not mapped on any published FIRM.
AO Zone O An area inundated by 100-year flooding (usually sheet flow on sloping terrain), for which average depths have been determined; flood depths range from 1 to 3 feet.
AR Zone AR An area inundated by flooding, for which BFEs or average depths have been determined.
B Zone B An area inundated by 500-year flooding; an area inundated by 100-year flooding with average depths of less than 1 foot or with drainage areas less than 1 square mile; or an area protected by levees from 100-year flooding.
BE Zone BE An area inundated by 500-year flooding; an area inundated by 100-year flooding with average depths of less than 1 foot or with drainage areas less than 1 square mile; or an area protected by levees from 100-year flooding.
BX Zone BX An area inundated by 500-year flooding; an area inundated by 100-year flooding with average depths of less than 1 foot or with drainage areas less than 1 square mile; or an area protected by levees from 100-year flooding.
C Zone C An area that is determined to be outside the 100- and 500-year floodplains.
CE Zone CE An area that is determined to be outside the 100- and 500-year floodplains.
CX Zone CX An area that is determined to be outside the 100- and 500-year floodplains.
D Zone D An area of undetermined but possible flood hazards.
FW Floodway An area that includes the channel of a river or other watercourse (Usually adjacent to Zone AE).
FWIC Floodway Contained in Channel An area where the floodway is contained within the channel banks and the channel is too narrow to show to scale. An arbitrary channel width of 3 meters is shown. BFEs are not shown in this area, although they may be reflected on the corresponding profile
IN Area In SFHA This is an area inundated by 100-year flooding for which BFEs or velocity may have been determined. No distinctions are made between the different flood hazard zones that may be included within the SFHA.
NM Area Not Mapped An area that is located within a community or county that is not mapped on any published FIRM.
OUT Area Not Mapped An area designated as outside a “Special Flood Hazard Area” (or SFHA) on a FIRM. This is an area inundated by 500-year flooding; an area inundated by 100-year flooding with average depths of less than 1 foot or with drainage areas less than 1 square mile
UNDES Area of Undesignated Flood Hazard A body of open water, such as a pond, lake ocean, etc., located within a community’s jurisdictional limits, that has no defined flood hazard.
V Zone V An area inundated by 100-year flooding with velocity hazard (wave action); no BFEs have been determined.
VE Zone VE An area inundated by 100-year flooding with velocity hazard (wave action); BFEs have been determined.
X Zone X An area that is determined to be outside the 100- and 500-year floodplains.
X5 Zone X (500-year) An area inundated by 500-year flooding; an area inundated by 100-year flooding with average depths of less than 1 foot or with drainage areas less than 1 square mile; or an area protected by levees from 100-year flooding.
X500 Zone X (500-year) An area inundated by 500-year flooding; an area inundated by 100-year flooding with average depths of less than 1 foot or with drainage areas less than 1 square mile; or an area protected by levees from 100-year flooding.
X500IC 500-year Flood Discharge Contained in Channel An area where the 500-year flooding is contained within the channel banks and the channel is too narrow to show to scale. An arbitrary channel width of 3 meters is shown.
A(1-30) Zone A1-30 Areas subject to inundation by the 1-percent-annual-chance flood event determined by detailed methods., for which base flood elavations have been established.
V(1-30) Zone V(1-30) Coastal area inundated by 100-year flooding with velocity hazard (wave action); no BFEs have been determined.
Z Area of Unknown Flood Hazard An area of Data Discrepancy or an Unclaimed Area. Internal TFHC designation.
N Area Not Mapped An area that is located within a community or county that is not mapped on any published FIRM (Usually a community not participating in NFIP). Internal TFHC designation.
AR/A Zone AR/A An area inundated by flooding, for which BFEs or average depths have not been determined.
AR/AE Zone AR/AE An area inundated by flooding, for which BFEs or average depths have been determined.
AR/AE Zone AR/AH An area inundated by flooding, for which BFEs or average depths have been determined.

 

 

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