Distributary

A river can split apart.

One big river can turn into many small streams. These streams flow away from the main river. This is called a distributary.

This often happens near the sea. It can also happen near a big lake. Some streams split and then join back together. Other streams flow away and never rejoin.

Sometimes, a small stream takes a lot of water. It can even become the main river! This can change how the land looks.

In some places, these streams flow into the desert. In other places, they flow into the ocean. It is a busy way for water to move.

A river can split into many parts. These parts are called distributaries.

A distributary is a stream that branches off from a main river. This is the opposite of a tributary. A tributary is a stream that flows into a larger river.

Distributaries often appear in river deltas. A delta is where a river meets an ocean or a lake.

In the Rhine-Meuse-Scheldt delta, several streams branch off. In Louisiana, the Atchafalaya River is a big distributary of the Mississippi River.

It takes much water from the Mississippi. A dam helps control this flow. This protects the ports of New Orleans and Baton Rouge.

Some distributaries do not rejoin the main river. Others do rejoin it later. In Australia, a stream that leaves and then returns is called an anabranch. In North America, these are often called braided rivers. Some streams flow into the sea. Others flow into dry deserts or inland lakes. The Okavango River is a special example. Its many branches end in a large inland delta.

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.

A distributary is a stream channel that branches off from a main river channel. This process is known as river bifurcation, which means the river splits into two or more paths. Distributaries are the exact opposite of tributaries. A tributary is a smaller stream that flows into a larger river to add water. In contrast, a distributary takes water away from the main channel and moves it elsewhere.

These branching channels are most common in river deltas. A delta forms when a river approaches a large body of water, such as an ocean or a lake. As the river slows down, it divides into complex networks of distributaries to spread its water out. This spreading often creates wide, marshy areas or new landforms.

However, distributaries do not always appear at the coast. They can also form inland on alluvial fans. An alluvial fan is a fan-shaped deposit of sediment made by a river. They can also occur when a tributary splits just before it meets a larger stream.

Sometimes, the way a distributary behaves can change the entire river system. A minor distributary might divert so much water that it eventually becomes the main route. In North America, these types of branching rivers are often called braided rivers. In Australia, people use the term anabranch for a distributary that leaves the main course and then rejoins it later. Some branches, however, never rejoin the original river. In English-speaking countries, these individual paths are often called arms or channels. For example, the Fraser River in Canada has the North, Middle, and South Arms.

The Atchafalaya River in Louisiana provides a famous example of how distributaries can shift power. It is a major distributary of the Mississippi River. Because the Atchafalaya has a steeper route to the Gulf of Mexico, it has captured more of the Mississippi's flow over several decades. To manage this, the Army Corps of Engineers completed the Old River Control Structure in 1963. This dam regulates the water to prevent the Atchafalaya from taking the entire Mississippi flow. Doing so protects the important ports of Baton Rouge and New Orleans.

Distributaries can also create unique connections between different parts of the world. The Casiquiare canal in South America is a remarkable inland distributary of the upper Orinoco. It flows southward into the Rio Negro. This creates a natural canal between the Orinoco and Amazon river systems. It is the largest river on Earth that links two major river systems. In Europe, the Rhine river uses distributaries like the IJssel, the Waal, and the Nederrijn to navigate the Rhine–Meuse–Scheldt delta.

In many parts of the world, these channels define the local geography. In China, the Huai River splits into three distinct streams. One stream even travels 168 kilometers to enter the Yellow Sea. In Africa, the Nile River has two main branches called the Rosetta and the Damietta. Ancient history tells us that the Nile once had seven distributaries. In Papua New Guinea, major rivers like the Fly River split into many branches. This creates wide, many-branched deltas near the Gulf of Papua.

Finally, some distributaries lead to very different destinations than others. Most rivers flow toward the sea, but some end in closed systems. The Okavango River in Africa ends in a large inland delta. Its distributaries do not flow into any other body of water. In Australia, many rivers from the Great Dividing Range form distributaries that flow into deserts. These often only flow during times of high water. They eventually end in shallow lakes or simply disappear into the sand. Whether they reach the ocean or end in a desert, distributaries are essential to how water shapes our planet.