Flood Facts for Kids

Flooding in a street

View of flooded New Orleans in the aftermath of Hurricane Katrina. New Orleans, because it is on a river delta and experiences hurricanes, has historically been very vulnerable to flooding. Katrina's extreme rainfall and poor infrastructure maintenance led to a levee breach which flooded large portions of the city.

A flood is an overflow of water on normally dry ground. The most common causes of floods are overflowing river, a dam break, snowmelt, or heavy rainfall. Less common causes are tsunamis, storm surges.

The most deadly flooding was in 1931 in China and killed between 2,000,000 and 4,000,000 people. Bangladesh is the most flood-prone area in the world.

During a flood, people try to move themselves and their most precious belongings to higher ground quickly. The process of leaving homes in search of a safe place is called flood evacuation.

Pollution of drinking water
Types of Floods
Causes of floods
Flood safety planning
- Control
Interesting facts about Floods
Related pages
Images for kids
See also

Pollution of drinking water

Autumn Mediterranean flooding in Alicante, Spain, September of 1997

During a flood, most water becomes polluted and not safe to drink. If people drink this dirty water, they may suffer from diseases such as typhoid and cholera, hepatitis and other such diseases. People can get ready to survive a flood by filling many containers with fresh and clean drinking water and storing other emergency supplies like medicine and food.

Types of Floods

Contemporary picture of the flood that struck the North Sea coast of Germany and Denmark in October 1634

"Regular" flooding in Venice, Italy

Flooding of a creek due to heavy monsoonal rain and high tide in Darwin, Northern Territory, Australia

Flood in Jeddah, covering the King Abdullah Street in Saudi Arabia

Areal

In spring time, the floods are quite typical in Ostrobothnia, a flat-lying area in Finland. A flood-surrounded house in Ilmajoki, South Ostrobothnia.

Floods can happen in flat or low-lying areas when rainfall or snowmelt happens faster than it can either infiltrate or run off. The extra water gathers in the lowest-lying areas and can sometimes become dangerously deep. Endorheic basins may experience areal flooding when precipitation happens faster than evaporation.

Riverine (Channel)

Floods occur in all types of river and stream channels, from the smallest ephemeral streams in humid zones to normally-dry channels in arid climates to the world's largest rivers. They can happen slowly or quickly (flash flooding).

Erosion, long periods of rain, quickly melting snow, monsoons, or tropical cyclones can cause floods near rivers with large catchment areas. These usually happen more slowly since the river is larger and can carry more water.

Rapid flooding events, including flash floods, usually happen near smaller rivers, rivers with steep valleys, rivers that flow for much of their length over areas where water doesn't soak into the ground, or normally-dry channels. Intense thunderstorms or a sudden release of water from begin a dam, landslide, or glacier cause rapid flooding.

Estuarine and coastal

Storm surges during high tides at sea cause flooding in estuaries and coastal areas. Waves go above the flood defenses. Sometimes tsunami or tropical cyclones are also the cause of flooding in these areas.

Causes of floods

Rainfall is the most common cause of flooding. Quick downpours can cause flash flooding, which
Snow melt is another cause of flooding.
Tsunamis and Storm Surge are less common ways that floods happen.
Low pressure systems or storms can cause coastal flooding.
If a dam breaks, it will suddenly release a large amount of water that will flood the riverbanks and areas near the river.
Drains that are not well maintained can clog and cause flooding.

Flood safety planning

Aftermath of flooding in Colorado, 2013

In the United States, the National Weather Service gives out the advice "Turn Around, Don't Drown" for floods. This means avoiding flooding areas rather than trying to cross them. Most cities have community-safety facilities and services including hospitals; emergency operations centers; and police, fire, and rescue services in areas that are prone to flooding.

Engineers who build large buildings, roads, and bridges plan for floods when they build their structures. They build the structures to be able to withstand floods as people are leaving the area.

In the United States, the Federal Emergency Management Agency, or FEMA, has a written plan for helping people in areas that have been flooded.

Control

Main page: Flood control

In many countries around the world, people have built defenses against flooding like detention basins, levees, bunds, reservoirs, and weirs. When these fail, emergency crews can come to the area with sandbags or portable inflatable tubes to redirect water.

Near the coast, sea walls, beach nourishment (putting sand on top of the beach to expand its width), and barrier islands help control flooding.

Near rivers and streams, erosion control measures can be taken to try to slow down or reverse the natural forces that cause many waterways to meander over long periods. Flood controls, such as dams, can be built and maintained over time.

In areas prone to urban flooding, drainage systems can be improved to direct water away from areas that are used regularly by citizens. Property owners can landscape their property to make sure water flows away from their buildings or homes. They can also use rain barrels, sump pumps, and check valves.

Beavers can be beneficial for flood control reasons. Beavers build and maintain beaver dams which will reduce the height of flood waves moving down the river.

Interesting facts about Floods

In the United States, flooding causes more death and damage than tornadoes, hurricanes, or lightning.
Many people like to live near water because water is good for agriculture and transport. They know the risk of flooding and are willing to take it.
It takes only six inches of quickly moving water to cause someone to fall and possibly drown.
Often, flood water may be contaminated (like sewage or harmful chemicals) or contain harmful debris, like branches, sticks, or poles.
The 1931 China floods were the deadliest series of floods on record.
A single acre of wetland can hold 330,000 gallons of water when saturated to a depth of one foot, enough to flood thirteen average-sized homes up to a person's thighs.
Floods can also be helpful. Ancient Egyptians relied on the Nile River‘s yearly flooding to aid their crops’ growth.

Images for kids

Flood due to Cyclone Hudhud in Visakhapatnam
A dog sitting on top of 2 feet of mud deposited by flooding in the 2018 Kerala floods in India. Flooding not only creates water damage, but can also deposit large amounts of sediment.
Flooding near Key West, Florida, United States from Hurricane Wilma's storm surge in October 2005
Flooding in a street of Natal, Rio Grande do Norte, Brazil in April 2013
Minor flooding in a parking lot off Juniper Street Atlanta on Christmas Eve from thunderstorms caused by an El Nino event. The same El Nino caused recorded highs for January in Atlanta.
Flash flooding caused by heavy rain falling in a short amount of time.
Dozens of villages were inundated when rain pushed the rivers of northwestern Bangladesh over their banks in early October 2005. The Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA's Terra satellite captured the top image of the flooded Ghaghat and Atrai Rivers on October 12, 2005. The deep blue of the rivers is spread across the countryside in the flood image.