Oxbow lake facts for kids

An oxbow lake is a U-shaped body of water that used to be part of a river. Imagine a river flowing along with lots of curves and bends. These bends are called meanders. Sometimes, a river's bend gets cut off from the main river, forming a separate lake. This usually happens during floods or when a narrow part of the bend breaks through. The river then flows in a straighter path, and the old bend becomes an oxbow lake.

How Do Oxbow Lakes Form?

Water in a river moves at different speeds. The water in the middle of the river, away from the sides, flows the fastest. Near the banks, the water moves much slower. When a river flows around a bend, the water on the outside of the curve moves faster than the water on the inside.

Erosion and Deposition at Work

The fast-moving water on the outside of the bend has a lot of power. It starts to wear away the river bank, a process called erosion. This means it picks up and carries away bits of mud, sand, and rock. At the same time, the slower water on the inside of the bend drops off the mud, sand, and plant pieces it was carrying. This process is called deposition.

Because of erosion on the outside and deposition on the inside, the river bend slowly moves and gets bigger. It keeps moving farther and farther away from the main river channel.

The Cut-Off Point

Eventually, the neck of the meander (the narrow strip of land between two parts of the bend) becomes very thin. During a flood, the river might take a shortcut, breaking through this narrow neck. When this happens, the river flows in a new, straighter path. The old, U-shaped bend is then cut off from the main river. This isolated bend becomes an oxbow lake. Over time, these lakes can slowly fill up with sediment and become swamps or even dry land.

Images for kids

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  This picture of the Nowitna River in Alaska shows two oxbow lakes. The shorter one is at the bottom, and a longer, more curved one is in the middle-right. You can also see a third oxbow lake forming! The land in the center of the big bend is very narrow. Soon, the river might break through, creating a new, straighter path and another oxbow lake.

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  You can easily see the old paths and curves of the Songhua River in northeast China in this satellite photo.

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  Here are the early stages of an oxbow lake forming in the Gower Peninsula of southwest Wales.

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  A Horseshoe or oxbow lake near Hughes, Arkansas. The bumps in the border show how the river's path changed. When the river cut off its old channel, the border stayed the same.

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  The Oxbow, a famous painting of an oxbow lake on the Connecticut River by Thomas Cole.

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  Oxbow lakes on New Zealand's Taieri River have been turned into water meadows (fields that can be flooded).

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  This image shows a proposed oxbow lake on Titan, a moon of Saturn, based on images from the Cassini spacecraft.

See also

In Spanish: Brazo muerto para niños