In a flood, water covers the land and washes into buildings

In a flood, water covers the land and washes into buildings

A flood is a great flowing or overflowing of water onto land that is not usually covered by water.

A flood happens when too much rain falls, brought by storms and strong winds, and which can't be absorbed by the soil.

Rivers burst their banks and the water spills onto the land. Strong winds blowing across the sea make huge waves that surge onto the land and flood coastal areas.

River Floods

Rivers floods happen when rivers and streams cannot carry away all the extra water that falls as rain or comes from melting snow. The water rises in the rivers and streams and overflows onto normally dry land. Floods destroy farmland, wash away people's houses and drown people and animals. Towns and cities are flooded too.

Coastal flooding

Waves surging onto the land during a storm is known as coastal flooding

Waves surging onto the land during a storm is known as coastal flooding

Coastal flooding can be caused by strong winds blowing waves onto the land. Hurricanes and major storms produce most coastal floods. Very high tides and tsunamis also flood the coasts.

In many countries, large groups of people live along the coasts and for these people coastal flooding can be very serious. Thousands of people have been drowned in coastal flooding in many parts of the world. 

Flash floods

In a flash flood, streams and rivers rise quickly.

In a flash flood, streams and rivers rise quickly.

A flash flood is a quick flood caused by a sudden cloudburst or thunder storm. Huge amounts of water fall in a short time and in cities and towns the drains overflow and roads become flooded. 

Flash floods also happen in mountainous areas, where steep slopes cause the water to travel at high speeds.

The rushing water erodes the soil, washing it away down the slopes. Flash floods often occur rapidly and with little warning.

Humans may also cause floods.  

Floods also sometimes occur when artificial structures such as dams fail.

Floods can happen if a dam wall breaks. ©iStock

Floods can happen if a dam wall breaks. ©iStock

If the dam is poorly designed or built in a place where earthquakes and landslides occur, the dam may break and the water will flood the land.

One dam failure in the United States of America occurred in 1972 when a dam used to store waste from a coal mine as well as water, collapsed after three days of rain. The flood drowned 118 people and caused $65 million in damages.

The dangers of a flood

When floodwaters rise slowly people have time to get ready and escape. They can move themselves and some of their property to higher ground, or build barriers to keep the water out of their homes. Sometimes the water rises quickly and people and cars get caught in the flood. Water gets into buildings causing damage, things are washed away, and people have to leave their homes.

Read about the different types of floods and flooding, watch animations:

http://www.floodsite.net/juniorfloodsite/html/en/student/thingstoknow/hydrology/floodtypes.html

Watch a video about how floods occur