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What are Tributaries?

Mary McMahon
Mary McMahon
Mary McMahon
Mary McMahon

Tributaries are the branches of a river, starting high up in a watershed and slowly working their way down to join other tributaries and eventually the mainstream, which drains to the sea. Tributaries come in a wide range of shapes and sizes, and the study of tributaries is a topic of interest for some biologists, because it is possible to use tributaries to follow pollution and various living organisms like invasive exotics back to their source. You can see tributaries on a map; look for the characteristic opening of a river on the sea, and then trace it inland. All of the small branches which appear are tributaries.

The word “tributary” comes from the same root as “tribute.” Both words come from the Latin tribuere, when means “to allot or distribute.” In a sense, tributaries could be said to be bringing tributes from the far reaches of a watershed to the river.

Some tributaries are little more than a trickle of water.
Some tributaries are little more than a trickle of water.

Rivers are designed to drain watersheds, areas of land which are surrounded by hills and mountains, creating a basin. Watersheds are also sometimes called “drainage basins.” The network of tributaries which combines to form a river is linked to numerous sources of water in a watershed, from areas which flood in the winter to glaciers which melt in the summer. Without tributaries and rivers, watersheds would slowly flood.

As tributaries meet up with each other, they become larger.
As tributaries meet up with each other, they become larger.

Some tributaries are little more than trickles in the land, while others are sizable rivers and creeks in their own right. All of them drain water, along with any substances which might have dissolved in the water, such as silt, decaying organic material, and pollution from places like farms, sewage treatment plants, and companies built along the banks of the tributary.

As tributaries meet up with each other, they become progressively larger, until they reach the main trunk of the river. Along the way, sediment settles out of the water, leaving a rich fertile layer of silt behind, along with any other materials which the tributary might have picked up. Eventually, the water reaches the ocean, where it will flow along with global currents, evaporate, and eventually start the cycle all over again.

Many nations have faced serious water pollution as a result of growing industrialization and human populations. Biologists often use tributaries to identify the sources of pollution; for example, if a river experiences an algae bloom, biologists might try to isolate the section of the river where the bloom is occurring before testing tributaries in that section to try and find the source of nutrients which is causing the bloom. Traveling along the tributary might reveal something like a leaking manure pit at a hog farm, or fertilizer runoff from a farm.

Frequently Asked Questions

What exactly are tributaries?

Tributaries are smaller streams or rivers that flow into a larger one, contributing to its volume. They are essential components of a watershed, where all water converges into a single main watercourse. Tributaries help distribute water throughout the ecosystem, supporting biodiversity and facilitating nutrient transport.

How do tributaries affect the ecosystems they flow through?

Tributaries play a crucial role in ecosystems by providing habitats for various aquatic species. They contribute to the ecological diversity by connecting different habitats and allowing species to migrate and disperse. Additionally, they are vital for nutrient cycling, sediment transport, and maintaining water quality within the watershed.

Can tributaries have their own tributaries?

Yes, tributaries can indeed have their own tributaries, creating a complex network of waterways within a watershed. This hierarchical system can extend several layers deep, with small streams feeding into larger ones, which in turn merge into even larger rivers, eventually leading to major water bodies like oceans.

What is the difference between a tributary and a distributary?

A tributary adds water to a larger stream or river, whereas a distributary, often found in river deltas, carries water away from the main river and distributes it into separate channels. Distributaries are common in areas where rivers meet the sea or a lake, dispersing water and sediments across a wide area.

How do human activities impact tributaries?

Human activities such as urban development, agriculture, and deforestation can significantly impact tributaries. Pollution, water diversion, and habitat destruction can alter water quality and flow, threatening the health of the ecosystem. Efforts to protect and restore tributaries are crucial for maintaining biodiversity and water resources.

Why is it important to preserve tributaries?

Preserving tributaries is vital for maintaining the integrity of the water cycle and ensuring the health of aquatic ecosystems. They are critical for flood control, groundwater recharge, and providing water for human use. Protecting tributaries also supports biodiversity, recreational activities, and the overall resilience of the environment against climate change.

Mary McMahon
Mary McMahon

Ever since she began contributing to the site several years ago, Mary has embraced the exciting challenge of being a AllThingsNature researcher and writer. Mary has a liberal arts degree from Goddard College and spends her free time reading, cooking, and exploring the great outdoors.

Learn more...
Mary McMahon
Mary McMahon

Ever since she began contributing to the site several years ago, Mary has embraced the exciting challenge of being a AllThingsNature researcher and writer. Mary has a liberal arts degree from Goddard College and spends her free time reading, cooking, and exploring the great outdoors.

Learn more...

Discussion Comments

lilly3456

Rivers don't always begin in hills or mountains. It is true that rivers start at a higher elevation then where the water ends up since water does flow downhill with gravity, but that higher elevation doesn't have to be as high as a hill or mountain. The rivers can also begin from a ground spring or from rain events (those head waters tend to only be visible when water is being collected), just as it can start from snowmelt.

momothree

@anon127923: Rivers begin in hills or mountains, where snowmelt collects and forms small streams called gullies. Gullies can grow larger as they collect more water, then becoming streams themselves. When one stream meets with another stream, they merge together. The smaller stream is the tributary. It takes many different tributary streams to form a river.

anon127923

you should include how rivers form tributaries.

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    • Some tributaries are little more than a trickle of water.
      By: Helen Hotson
      Some tributaries are little more than a trickle of water.
    • As tributaries meet up with each other, they become larger.
      By: Galyna Andrushko
      As tributaries meet up with each other, they become larger.