Floods and Flash Floods
Except for fire, floods are the most common and widespread of all natural disasters (FEMA,2003). Of all of the hazards facing West Virginia, floods constitute the greatest threat to property and lives. The Standard Flood Insurance Policy (SFIP) defines a flood as a “general and temporary condition of partial or complete inundation of two or more acres of normally dry land area or of two or more properties (at least one of which is your property) from overflow of inland or tidal waters, from unusual and rapid accumulation or runoff of surface waters from any source, or from mudflow.”
Most communities in the United States can experience some kind of flooding after spring rains, heavy thunderstorms, or winter snow thaws. Floods can be slow- or fast-rising but generally develop over a period of days. Flooding has caused the deaths of more than
10,000 people in the United States since 1900, and property damage from flooding totals more than $1 billion each year.
Dam failures and flash floods can cause a very large amount of damage very suddenly. As mentioned earlier, West Virginia’s topography and development patterns make it particularly vulnerable to flash flooding. Flash floods usually result from intense storms dropping large amounts of rain within a brief period. Antecedent moisture, including both saturated or frozen soil conditions, can cause flash flooding from moderate rainfall events. Flash floods occur with little or no warning and can reach their peak in only a few minutes.
Flood A general and temporary condition of partial or complete inundation of two or more acres of normally dry land area or of two or more properties (at least one of which is your property) from overflow of inland or tidal waters, from unusual and rapid accumulation or runoff of surface waters from any source, or from mudflow.
Flash Flood A flood event occurring with little or no warning, where water levels rise at an extremely fast rate.
Floodplain Any land area, including watercourse, susceptible to partial or complete inundation by water from any source.
Floodway The channel of a river or other watercourse and adjacent land areas that must be reserved in order to discharge the 1-percent-annual-chance flood without cumulatively increasing the water surface elevation by more than a designated height.