Floods—facts And Information - National Geographic

(Heavy Rainfall Can Cause Huge Earthquakes)

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What is a flash flood?

A flood occurs when water overruns land that's normally dry, which can happen in many ways.

Excessive rain, a ruptured dam or levee, rapidly melting snow or ice, or even an unfortunately placed beaver dam can overwhelm a river, spreading over the adjacent land, called a floodplain. Coastal flooding occurs when a large storm or tsunami causes the sea to surge inland.

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Most floods take hours or even days to develop, giving residents time to prepare or evacuate. 

(Watch a Wall of Water Race Up a River)

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