There are few places on Earth where flooding is not a concern. Any area where rain falls is vulnerable to floods, though rain is not the only cause.

A flood occurs when water inundates land that's normally dry, which can happen in a multitude of ways.

Excessive rain, a ruptured dam or levee, rapid melting of 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.

Most floods take hours or even days to develop, giving residents time to prepare or evacuate. Others generate quickly and with little warning. So-called