Glossary of Terms
The flood having a one-percent chance of being equaled of exceeded in magnitude in any given year. It is not a flood occurring every 100 years.
Base Flood Elevation (BFE)
The height (above sea-level) that flood waters will reach at a given location in the event of the 100-year flooding event.
Community Rating System (CRS)
A National Flood Insurance Program that provides incentives for NFIP communities to complete activities that reduce flood hazard risk. When the community completes specified activities, the insurance premiums of NFIP policyholders in these communities are reduced.
A tool used by NFIP to ensure compliance with community floodplain management ordinances, and to determine the proper insurance premium rate.
A rapid rise in water levels associated with heavy rainfall, or failure of dam. These fast moving waters can move boulders, tear out trees, and destroy buildings.
A general and temporary condition of partial or complete inundation of normally dry land areas from : (a) the overflow of inland or tidal waters; (b) the unusual and rapid accumulation of runoff of surface water from any surface.
Flood Insurance Rate Map (FIRM)
The insurance and floodplain management map issued by FEMA that identifies areas of 100-year flood hazard in a community. In some areas the map also shows base flood elevations and 500-year floodplain boundaries and occasionally, regulatory floodway boundaries. These maps are usually located at the Town/City Hall.
Flood Insurance Study (FIS)
An engineering study performed by FEMA to identify flood hazard areas, flood insurance risk zones, and other flood data in a community.
A flood is imminent or occurring. Take immediate action to protect lives/property
Conditions are in place for a flood event but location and magnitude are still uncertain. Prepare for flooding.
Any land area susceptible to inundation by floodwaters from any source.
Geographical Information Systems (GIS)
A system of computers, spatial data, and personnel to help store, manipulate, and analyze and display geographically referenced information. Generally it is used to map physical features on the earth.
Sustained actions taken to reduce or eliminate long-term risk from hazards and their effects.
An intense tropical cyclone, formed in the atmosphere over warm ocean areas, in which wind speeds reach 47 miles-per-hour or more and blow in a large spiral around a relatively calm center or “eye”. Hurricanes develop over the North Atlantic Ocean, northeast Pacific Ocean, or the South Pacific Ocean east of 160 degrees longitude. Hurricane circulation is counter-clockwise in the northern hemisphere and clockwise in the southern hemisphere.
Letter of Map Amendment
Report that must be submitted to FEMA to change a FIRM in order to move a property out of the 100 year floodplain.
The water from rainfall that is not absorbed by the ground that flows in the local drainage system, and ultimately rivers and streams.
Flooding of or produced by a river.
Special Flood Hazard Area (SFHA)
An area that has a one percent chance of being flooded in any given year. Also called the 100-year floodplain, this area is shaded on the Flood Insurance Rate Map into FIRM Zones.
Flooding that has occurred where there has been development within stream floodplains. Urbanization in floodways increases the magnitude and frequency of floods by destroying the floodways and natural wetlands that serve as natural basins for flood waters.
The geographic area that contributes surface water from rain, or melting snow to a particular stream or river system.
Flood hazard areas identified on the Flood Insurance Rate Map are identified as a Special Flood Hazard Area (SFHA). SFHA are defined as the area that will be inundated by the flood event having a 1-percent chance of being equaled or exceeded in any given year. The 1-percent annual chance flood is also referred to as the base flood or 100-year flood. SFHAs are labeled as Zone A, Zone AO, Zone AH, Zones A1-A30, Zone AE, Zone A99, Zone AR, Zone AR/AE, Zone AR/AO, Zone AR/A1-A30, Zone AR/A, Zone V, Zone VE, and Zones V1-V30. Moderate flood hazard areas, labeled Zone B or Zone X (shaded) are also shown on the FIRM, and are the areas between the limits of the base flood and the 0.2-percent-annual-chance (or 500-year) flood. The areas of minimal flood hazard, which are the areas outside the SFHA and higher than the elevation of the 0.2-percent-annual-chance flood, are labeled Zone C or Zone X (unshaded).