Glossary of Flood Terms

100-year flood:
The flood having a 1% or greater annual probability of occurring.

500-year flood:
The flood having a 0.2% or greater annual probability of occurring.

Base Flood: The flood having a one percent chance of being equaled or exceeded in any given year (also called the “100-year flood” and the “regulatory flood”).

Base Flood Elevation (BFE):
The water-surface elevation associated with the base flood.

Community Number:
A 6-digit designation identifying each NFIP community. The first two numbers are the state code. The next four are the FIMA-assigned community number. An alphabetical suffix is added to a community number to identify revisions in the Flood Insurance Rate Map for that community.

Flood Insurance Rate Map (FIRM): An official map of Walton County issued by the Federal Emergency Management Agency which delineated both the areas of special flood hazard and the risk premium zones applicable to the community.

Flood Insurance Study (FIS):
The official hydrology and hydraulics report provided to Walton County by FEMA. The study contains an examination, evaluation, and determination of flood hazards, and, if appropriate, corresponding water surface elevations, or an examination, evaluation, and determination of mudslide (i.e., mudflow) and other flood-related erosion hazards. The study may also contain flood profiles, as well as the FIRM, and other related data and information.

Floodplain: Any land area susceptible to being inundated by flood waters from any source.

Freeboard: The additional height usually expressed as a factor of safety in feet above a flood level, for purposes of floodplain management. “Freeboard” tends to compensate for the many unknown factors that could contribute to flood heights greater than the height calculated for a selected size flood and flood way conditions, such as wave action, blockage of bridge or culvert openings, and the hydrological effect of urbanization of the watershed.

Free of Obstruction: Any type of lower area enclosure or other construction element will not obstruct the flow of velocity water and wave action beneath the lowest horizontal structural member of the lowest floor of an elevated building during a base flood event. This requirement applies to the structures in velocity zones (V-Zones) and in Coastal A zones.

Panel: Panel number is numerical designation used to identify the FIRM Map associated with a given area. The first six digits of the Panel number is the community number.

Panel Date:
This is the date recorded in the FEMA FMSIS database, which is associated with the given Panel Number.

Repetitive Loss Property: A property for which two or more National Flood Insurance Program losses of at least $1,000 each have been paid within any 10 year period since 1978.

Special Flood Hazard Area (SFHA):
An area designated as within a "Special Flood Hazard Area" (or SFHA) on the Walton County FIRM. This is an area inundated by 1% annual chance 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. These may include Zones A, AE, or VE.