Distributary

A river does not always stay in one single path. Sometimes, a main stream will split and branch into new paths. These branching streams are called distributaries. A distributary is the opposite of a tributary. A tributary is a smaller stream that flows into a larger river. A distributary is a stream that branches off from a main channel.

You often find these branching paths in river deltas. This happens where a river reaches a lake or an ocean. The water divides into many smaller networks to spread out.

How these branches work can change the whole river. Sometimes, a small branch can take a lot of water. If it takes enough water, it might even become the main route. In North America, these branching rivers are often called braided rivers. In Australia, people use the word anabranch for a stream that leaves and then rejoins the river. Some branches never rejoin the main path at all.

In Louisiana, the Atchafalaya River is a major distributary of the Mississippi River. Because it has a steeper route to the Gulf of Mexico, it captures more water from the Mississippi. To manage this, the Army Corps of Engineers finished a dam called the Old River Control Structure in 1963. This dam helps keep the main flow of the Mississippi moving toward ports like New Orleans.

Many famous rivers around the world have these branches. In South America, the Casiquiare canal is a very special inland distributary. It connects the Orinoco and Amazon river systems. It is the largest river on Earth that links two major systems.

In Europe, the Rhine river has three main distributaries called the IJssel, the Waal, and the Nederrijn. The Nile river in Africa has two main branches called the Rosetta and the Damietta. Long ago, a writer named Pliny the Elder said the Nile had seven branches. These branches helped shape the land of the Nile Delta.

Distributaries can also appear far away from the ocean. They can form on alluvial fans, which are flat areas made of river deposits. In California, the Kings River creates a large alluvial fan. Its branches flow north to the Pacific Ocean or south to Tulare Lake. In Idaho, the Teton River splits into the North Fork and South Fork. These two channels join back together miles apart. In Wyoming, North Two Ocean Creek splits into the Pacific Creek and Atlantic Creek. These two branches eventually flow into different oceans.

These water paths create many different kinds of land. In Papua New Guinea, the Fly River splits into many branches near the Gulf of Papua.

This creates wide and marshy deltas. Some rivers, like the Okavango River in Africa, end in a large inland delta. These branches do not flow into an ocean at all. They simply end in a large area of land. Whether they flow to the sea or into a desert, distributaries show how water moves across our world.