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The Many Effects of Flooding

The Many Effects of Flooding

Floods can be destructive to humans and the natural environment, but they also help to drive biodiversity and are essential to the functioning of many ecosystems.

Grades

2 - 12

Subjects

Earth Science, Climatology, Geography, Physical Geography

Image

1931 Yangtze River Flood

In 1931, water overwhelmed the banks of the Yangtze and Huai Rivers, resulting in the Central China flood. Killing at least hundreds of thousands and potentially millions of people, it was one of the worst flooding events in recorded history. Here, people near the Yangtze River are shown.

Photograph from Adrienne Livesey, Elaine Ryder, and Irene Brien
In 1931, water overwhelmed the banks of the Yangtze and Huai Rivers, resulting in the Central China flood. Killing at least hundreds of thousands and potentially millions of people, it was one of the worst flooding events in recorded history. Here, people near the Yangtze River are shown.
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Rivers are very important. Humans rely on rivers for food and water. But rivers can destroy things too. Rivers can flood, or rise over their banks. The water can run onto the nearby land.

Many times, floods can be deadly. They can kill humans and wildlife. But floods are not always bad. Some ecosystems need floods every once in a while.

Floods Can Cause Harm

Flooding can be bad for wildlife. The water can drown animals. They can destroy habitats too. For example, a flood in India in 2012 killed many one-horned rhinos (Rhinoceros unicornis).

Floodwater can pick up dirt from riverbanks. This makes the water dirty. Too much dirt can clog rivers and streams. This keeps the river from flowing.

Floods can carry pollution. This can include pieces of trash. Sometimes, floodwater carries pollution to the sea. This can harm marine life.

In addition, floodwater can carry disease. Some deadly diseases live in water. These include hepatitis A and cholera.

Some Floods Are Helpful

Not everything about floods is bad. Sometimes, floods are helpful. They bring new life to ecosystems.

Floodwater carries nutrients to the nearby land. Over time, the water dries up. It leaves behind particles of dirt and mud. These particles are called sediment. Sometimes, sediment can be good. It can improve the dirt. This helps plants grow.

Floods are important to some animals. Some animals see floods as a sign that it is time to mate. For other animals, floods are a sign that it is time to migrate. To migrate means move from one habitat to another.

Helping Fish, Boosting Water Supplies

Small floods can be good for fish. Floods leave sediment on riverbeds. Baby fish can grow in it. The flood waters also carry nutrients. Small animals in the water eat these nutrients.

Floods can help refill freshwater supplies. They can keep lakes from drying up. Floods also help marshes and swamps. Many animals depend on marshes and swamps. In dry seasons, they might dry up. But floods help refill the wetlands. They keep the ecosystem going.

Floods are a part of nature. They can be helpful. But they can also be harmful. Floods can destroy living things and the environment. But some ecosystems need floods to survive.

Media Credits

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Director
Tyson Brown, National Geographic Society
Author
National Geographic Society
Production Managers
Gina Borgia, National Geographic Society
Jeanna Sullivan, National Geographic Society
Program Specialists
Sarah Appleton, National Geographic Society, National Geographic Society
Margot Willis, National Geographic Society
Producer
Clint Parks
other
Last Updated

January 22, 2024

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