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What Are the Main Features of a Flood?

Flooding is one of the most common natural disasters in the United States, occurring in nearly every state in the United States. A flood is typically temporary, and involves the submersion of two or more acres of land that is normally dry. Floods occur for a variety of reasons, including high volumes of rain, rapid thawing of ice, ice jams and water overflowing its banks. Floods, regardless of cause, can have a devastating impact on people and the environment.

  1. The Wave

    • The flood wave is the name given to the rise and fall of river levels. The highest point of the flood wave as it passes a particular location is referred to as its crest. The crest of the water moves downstream following the flow of the water. Initially the crest moves rather quickly; however, as the volume of water increases downstream, the crest slows which prolongs the duration of the flood.

    Types of Flooding

    • There are three main types of floods including riverine flooding, flash flooding and ice jam/debris flooding. Riverine flooding typically refers to floods caused by water that exceeds the volume that can be held within the body of water's banks, spilling over the banks onto adjacent land. Flash flooding can occur anywhere there is rain. This results from a high velocity of water pooling up in creeks and on roads. Flash flooding occurs quickly, but recedes rather quickly too.. Ice jam or debris flooding is caused by the jamming of ice or debris at a natural or man-made obstruction which in turn restricts the flow of water. For example, a jam might occur at the mouth of a lake, a turn in a river or at a bridge.

    Damage to Property

    • One of the major features of a flood is its capacity to destroy much of what lays in the water's path. Flooding adversely impacts drainage systems which might cause raw sewage to contaminate water systems. Homes, out buildings, businesses, vehicles and other personal property items can be damaged by flood waters. Flooding can contaminate water with toxic chemicals, debris and dead wildlife. Floods also damage the coastline, eroding shorelines and washing up debris. Overland flooding damages crops, adversely affecting the economy and food supply.

    Loss of Life

    • Flooding accounts for approximately one-third of fatalities in the United States related to weather. Flash flooding is particularly dangerous to both humans and animals. Water during a flash flood may flow fast and furious, often with little warning. Approximately 75 percent of fatalities occur after dark where it is difficult for people to gauge water hazards. Pets may be stranded at home due to flood waters that rise when owners are away from the home. Farm animals can also be adversely affected by flood water, as animals can lose their lives and contract illnesses due to contaminated water supplies.

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