Floods are one of the most destructive natural hazards associated with thunderstorms. In most years, flooding causes more deaths and damage than any other hydro meteorological phenomena. In many years it is common for three-quarters of all federally declared disaster declarations to be due, at least in part, to flooding.

Flood and Flash Flood Occurrence
Flooding and flash flooding are not restricted to specific areas of the country. Certain geographical locations may be more prone to annual flooding or a flash flood from a sudden rainfall.

For many years, people have built homes and businesses on flood plains, low lying land adjacent to rivers and streams.

This increases the probabilities of property damage and loss of life from a flash flood's quick moving, often unexpected, wall of water or the slower inundation of a flood.

Flash Floods
A flash flood is typically caused by sudden, excessive rainfall that sends a river, stream or other body of water rapidly out of its banks. Often this occurs in a short amount of time, only several hours or even less.

They can also be caused by ice jams on rivers in conjunction with a winter or spring thaw, or occasionally even a dam break.

The constant influx of water finally causes a treacherous overflow to begin, powerful enough to sweep vehicles away, roll boulders into roadways, uproot trees, level buildings, and drag bridges off their piers. Most frightening is the rapidity with which the water rises.

Torrential rains associated with land falling tropical systems sometimes produce flash floods.

In the western United States, the soil is generally dry, sandy and unable to absorb large amounts of water. Heavy rains from showers and thunderstorms can quickly fill dry stream and river beds, sending torrents of water downstream.

In order to get the statistics on the flood fatalities please refer to the site below. This has an excellent graph; all vehicle related deaths are shown in red.

http://weather.gov/oh/hic/flood_stats/recent_individual_deaths.html

If you are ever in a situation where you think you have to drive through water on the pavement, don’t do it. It is always hard to tell how deep the water is and your life is not worth taking the risk. Nearly half of all flash flood deaths are auto related. Even 6 inches of fast moving flood water can knock you off your feet and at a depth of 2 feet will float your car.

http://ks.water.usgs.gov/Kansas/pubs/fact-sheets/fs.024-00.html

During the 20th century, floods were the number-one natural disaster in the United States in terms of number of lives lost and property damage. They can occur at any time of the year, in any part of the country, and at any time of the day or night. Most lives are lost when people are swept away by flood currents, whereas most property damage results from inundation by sediment-laden water. Flood currents also possess tremendous destructive power, as lateral forces can demolish buildings and erosion can

undermine bridge foundations and footings leading to the collapse of structures. The accompanying map and table locate and describe 32 of the most significant floods of the 20th century. 

The sort of flooding that most people are familiar with occurs when an unusually large number of rainstorms hit an area in a fairly short period of time. In this case, the rivers and streams that divert the water to the ocean are simply overwhelmed.

FEMA News Photo
In 1993, the Mississippi River was so heavily flooded that it rose above the level of major bridges, such as this one in Quincy, Illinois.

The rule for being safe in a flooding situation is simple: Head for higher ground and stay away from flood waters!