A distributary, or a distributary channel, is a stream that branches off and flows away from a main stream channel. Distributaries are a common feature of river deltas. The phenomenon is known as river bifurcation. The opposite of a distributary is a

tributary A tributary, or affluent, is a stream or river that flows into a larger stream or main stem (or parent) river or a lake. A tributary does not flow directly into a sea or ocean. Tributaries and the main stem river drain the surrounding drainag ...

, which flows ''towards'' and joins another stream. Distributaries are often found where a stream approaches a

lake A lake is an area filled with water, localized in a basin, surrounded by land, and distinct from any river or other outlet that serves to feed or drain the lake. Lakes lie on land and are not part of the ocean, although, like the much lar ...

or an

ocean The ocean (also the sea or the world ocean) is the body of salt water that covers approximately 70.8% of the surface of Earth and contains 97% of Earth's water. An ocean can also refer to any of the large bodies of water into which the wo ...

. They can also occur inland, on alluvial fans, or where a tributary stream bifurcates as it nears its

confluence In geography, a confluence (also: ''conflux'') occurs where two or more flowing bodies of water join to form a single channel. A confluence can occur in several configurations: at the point where a tributary joins a larger river ( main stem); ...

with a larger stream. In some cases, a minor distributary can divert so much water from the main channel that it can later become the main route.

Related terms

Common terms to name individual river distributaries in

English-speaking countries The following is a list of English-speaking population by country, including information on both native speakers and second-language speakers. List * The European Union is a supranational union composed of 27 member states. The total ...

are ''arm'' and ''channel''. These terms may refer to a distributary that does not rejoin the channel from which it has branched (e.g., the North, Middle, and South Arms of the Fraser River, or the West Channel of the Mackenzie River), or to one that does (e.g. Annacis Channel and Annieville Channel of the Fraser River, separated by Annacis Island). In Australia, the term '' anabranch'' is used to refer to a distributary that diverts from the main course of the river and rejoins it later. In North America an anabranching river is called a ''braided stream''.

North America

Louisiana Louisiana , group=pronunciation (French: ''La Louisiane'') is a U.S. state, state in the Deep South and South Central United States, South Central regions of the United States. It is the List of U.S. states and territories by area, 20th-smal ...

, the Atchafalaya River is an important distributary of the

Mississippi River The Mississippi River is the second-longest river and chief river of the second-largest drainage system in North America, second only to the Hudson Bay drainage system. From its traditional source of Lake Itasca in northern Minnesota, it ...

. Because the Atchafalaya takes a steeper route to the

Gulf of Mexico The Gulf of Mexico ( es, Golfo de México) is an ocean basin and a marginal sea of the Atlantic Ocean, largely surrounded by the North American continent. It is bounded on the northeast, north and northwest by the Gulf Coast of the United S ...

than does the Mississippi, over several decades the Atchafalaya has captured more and more of the Mississippi's flow, after the Mississippi meandered into the Red River of the South. The Old River Control Structure, a dam which regulates the outflow from the Mississippi into the Atchafalaya, was completed by the Army Corps of Engineers in 1963. The dam is intended to prevent the Atchafalaya from capturing the main flow of the Mississippi and stranding the ports of

Baton Rouge Baton Rouge ( ; ) is a city in and the capital of the U.S. state of Louisiana. Located the eastern bank of the Mississippi River, it is the parish seat of East Baton Rouge Parish, Louisiana's most populous parish—the equivalent of countie ...

and

New Orleans New Orleans ( , ,New Orleans

John McPhee John Angus McPhee (born March 8, 1931) is an American writer. He is considered one of the pioneers of creative nonfiction Creative nonfiction (also known as literary nonfiction or narrative nonfiction or literary journalism or verfabula) is ...

, The Control of Nature In

British Columbia British Columbia (commonly abbreviated as BC) is the westernmost Provinces and territories of Canada, province of Canada, situated between the Pacific Ocean and the Rocky Mountains. It has a diverse geography, with rugged landscapes that include ...

, Canada, the Fraser River has numerous sloughs and side-channels which may be defined as distributaries. This river's final stretch has three main distributaries: the North Arm and the South Arm, and a few smaller ones adjoining them. Examples of inland distributaries: * Teton River—a tributary of Henrys Fork in

Idaho Idaho ( ) is a state in the Pacific Northwest region of the Western United States. To the north, it shares a small portion of the Canada–United States border with the province of British Columbia. It borders the states of Montana and W ...

—splits into two distributary channels, the North Fork and South Fork, which join Henrys Fork miles apart. *

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National Landmark within Wyoming's Teton Wilderness on the

Continental Divide A continental divide is a drainage divide on a continent such that the drainage basin on one side of the divide feeds into one ocean or sea, and the basin on the other side either feeds into a different ocean or sea, or else is endorheic, no ...

where North Two Ocean Creek splits into two distributaries, Pacific Creek and Atlantic Creek, which ultimately flow into their respective oceans. * Kings River (California) has deposited a large alluvial fan at the transition from its canyon in the Sierra Nevada mountains to the flat Central Valley. Distributaries flow north into the Pacific Ocean via the

San Joaquin River The San Joaquin River (; es, Río San Joaquín) is the longest river of Central California. The long river starts in the high Sierra Nevada, and flows through the rich agricultural region of the northern San Joaquin Valley before reaching ...

and south into an endorheic basin surrounding Tulare Lake. * The Qu'Appelle River, in

Saskatchewan Saskatchewan ( ; ) is a province in western Canada, bordered on the west by Alberta, on the north by the Northwest Territories, on the east by Manitoba, to the northeast by Nunavut, and on the south by the U.S. states of Montana and North ...

and

Manitoba , image_map = Manitoba in Canada 2.svg , map_alt = Map showing Manitoba's location in the centre of Southern Canada , Label_map = yes , coordinates = , capital = Win ...

, is a distributary of the South Saskatchewan River. Its flow is controlled by the Qu'Appelle River Dam. This dam forms the southern arm of Lake Diefenbaker.

South America

The Casiquiare canal is an inland distributary of the upper Orinoco, which flows southward into the Rio Negro, forming a unique natural

canal Canals or artificial waterways are waterways or engineered channels built for drainage management (e.g. flood control and irrigation) or for conveyancing water transport vehicles (e.g. water taxi). They carry free, calm surface fl ...

between the Orinoco and Amazon river systems. It is the largest river on the planet that links two major river systems.

Europe

*The IJssel, the Waal and the Nederrijn (Lower Rhine) are the three principal distributaries of the

Rhine The Rhine ; french: Rhin ; nl, Rijn ; wa, Rén ; li, Rien; rm, label=Sursilvan, Rein, rm, label=Sutsilvan and Surmiran, Ragn, rm, label=Rumantsch Grischun, Vallader and Puter, Rain; it, Reno ; gsw, Rhi(n), including in Alsatian dialect, Al ...

. These are formed by two separate bifurcations within the Rhine–Meuse–Scheldt delta. *The Akhtuba River is a major distributary of the Volga. The bifurcation occurs close to, but before, the Volga Delta. * The

Tärendö River The Tärendö River (Swedish: ''Tärendö älv'', Meänkieli: ''Täränönväylä'') is a small distributary river to the Kalix River in Norrbotten, Sweden. It is the second largest bifurcation in the world (second only to the Casiquiare canal, So ...

in northern Sweden is an inland distributary, far from the mouth of the river. It begins at the Torne River and ends at the Kalix River. * The Little Danube in

Slovakia Slovakia (; sk, Slovensko ), officially the Slovak Republic ( sk, Slovenská republika, links=no ), is a landlocked country in Central Europe. It is bordered by Poland to the north, Ukraine to the east, Hungary to the south, Austria to the ...

branches off from the

Danube The Danube ( ; ) is a river that was once a long-standing frontier of the Roman Empire and today connects 10 European countries, running through their territories or being a border. Originating in Germany, the Danube flows southeast for , ...

near Bratislava, and flows into the Vah before rejoining the main river near Komárno. The area in the middle is the largest freshwater island in Europe. * The Abbey River,

Limerick Limerick ( ; ga, Luimneach ) is a western city in Ireland situated within County Limerick. It is in the province of Munster and is located in the Mid-West which comprises part of the Southern Region. With a population of 94,192 at the 2016 ...

, in

Ireland Ireland ( ; ga, Éire ; Ulster Scots dialect, Ulster-Scots: ) is an island in the Atlantic Ocean, North Atlantic Ocean, in Northwestern Europe, north-western Europe. It is separated from Great Britain to its east by the North Channel (Grea ...

is a distributary arm of the

River Shannon The River Shannon ( ga, Abhainn na Sionainne, ', '), at in length, is the longest river in the British Isles. It drains the Shannon River Basin, which has an area of , – approximately one fifth of the area of the island of Ireland. The Sha ...

. It rejoins the Shannon to form an island upon which King John's Castle is built.

Asia

Eastern Asia

The

Huai River The Huai River (), formerly romanized as the Hwai, is a major river in China. It is located about midway between the Yellow River and Yangtze, the two longest rivers and largest drainage basins in China, and like them runs from west to east ...

in China splits into three streams. The main stream passes through the Sanhe Sluice, goes out of the Sanhe river, and enters the

Yangtze River The Yangtze or Yangzi ( or ; ) is the longest river in Asia, the third-longest in the world, and the longest in the world to flow entirely within one country. It rises at Jari Hill in the Tanggula Mountains (Tibetan Plateau) and flow ...

through Baoying Lake and Gaoyou Lake. On the east bank of

Hongze Lake Hongze Lake or Lake Hungtse () is the fourth largest freshwater lake in China, in Jiangsu Province, China and is encompassed by the prefecture-level cities Suqian (Sihong County and Siyang County) and Huai'an (Xuyi County and Hongze County). Lak ...

, another stream goes out of Gaoliangjian Gate and enters the Yellow Sea at the

port A port is a maritime facility comprising one or more wharves or loading areas, where ships load and discharge cargo and passengers. Although usually situated on a sea coast or estuary, ports can also be found far inland, such as ...

of Bidan through Subei Guan'gai Zongqu, the main

irrigation Irrigation (also referred to as watering) is the practice of applying controlled amounts of water to land to help grow crops, landscape plants, and lawns. Irrigation has been a key aspect of agriculture for over 5,000 years and has been dev ...

channel of Northern Jiangsu); its total length is 168 kilometers. The third stream leaves the Erhe lock on the northeast bank of Hongze Lake, passes the Huaishuhe River to the north of Lianyungang city, and flows into Haizhou Bay through the Hongkou.

Indian Subcontinent

* Kollidam River is a distributary of the Kaveri River. * Himalayan rivers including Ganges, Brahmaputra and Indus plus many tributaries form inland distributaries over vast alluvial fans as they transition from the mountain region to the flat Indo-Gangetic Plain. These areas are highly flood-prone, for example the 2008 Bihar flood on the Kosi River. * Padma River is the main distributary of the Ganges in

Bangladesh Bangladesh (}, ), officially the People's Republic of Bangladesh, is a country in South Asia. It is the List of countries and dependencies by population, eighth-most populous country in the world, with a population exceeding 165 million pe ...

. * Hoogli River is a Ganges distributary that flows through

India India, officially the Republic of India ( Hindi: ), is a country in South Asia. It is the seventh-largest country by area, the second-most populous country, and the most populous democracy in the world. Bounded by the Indian Ocean on the ...

, whereas most of the Ganges- Brahmaputra complex enters the sea through

. * Nara River is a distributary of the Indus River.

Africa

* The Nile River has two distributaries, the Rosetta and the Damietta branches. According to

Pliny the Elder Gaius Plinius Secundus (AD 23/2479), called Pliny the Elder (), was a Roman author, naturalist and natural philosopher, and naval and army commander of the early Roman Empire, and a friend of the emperor Vespasian. He wrote the encyclopedic ...

it had in ancient times seven distributaries (east to west): ** The Pelusiac ** The Tanitic ** The Mendesian ** The Phatnitic ** The Sebennytic ** The Bolbitine ** The Canopic :See History of the Nile Delta. * The Okavango River ends in many distributaries in a large inland delta called the Okavango Delta. It is an example of distributaries that do not flow into any other body of water.

Oceania

Australia

A number of the rivers that flow inland from Australia's Great Dividing Range form distributaries, most of which flow only intermittently during times of high river levels and end in shallow lakes or simply peter out in the deserts. Yarriambiack Creek, which flows from the Wimmera River into Lake Coorong, and Tyrrell Creek, which flows from the Avoca River into

Lake Tyrrell Lake Tyrrell (also known as Lake Tyrrell Wildlife Reserve) is a shallow, salt-crusted depression in the Mallee district of north-west Victoria, in Australia. The name 'Tyrrell' is derived from the local Wergaia word for 'sky', the Boorong A ...

, are two distributaries in Victoria. The

Narran River Narran River, a watercourse of the Barwon catchment within the Murray–Darling basin, is located in the Southern Downs district of Queensland and Orana district of New South Wales, Australia. The river rises south west of Dirranbandi, as a ...

flows from the

Balonne River The Balonne River, part of the Murray-Darling Basin system, is a short yet significant part of the inland river group of South West Queensland, Australia. Course and features The river is a continuation of the Condamine River. After flowing ...

Queensland ) , nickname = Sunshine State , image_map = Queensland in Australia.svg , map_caption = Location of Queensland in Australia , subdivision_type = Country , subdivision_name = Australia , established_title = Before federation , established_ ...

into

Narran Lake The Narran Wetlands, also known as the Narran Lakes, contained within the Narran Lake Nature Reserve, comprise a series of protected ephemeral lakes and swamps fed by the Narran River in the north-west of New South Wales, Australia. The reserv ...

New South Wales ) , nickname = , image_map = New South Wales in Australia.svg , map_caption = Location of New South Wales in AustraliaCoordinates: , subdivision_type = Country , subdivision_name = Australia , established_title = Before federation , es ...

Papua New Guinea

Many of Papua New Guinea's major rivers flow into the Gulf of Papua through marshy, low-lying country, allowing for wide, many-branched deltas. These include the Fly River, which splits into three major and several minor rivers close to its mouth. The Bamu River splits into several channels close to its mouth, among them the ''Bebea'', ''Bina'', ''Dibiri'', and ''Aramia''. The

Kikori River The Kikori River is a major river in southern Papua New Guinea on the island of New Guinea. The river has a total length of and flows southeast into the Gulf of Papua, with its delta at the head of the gulf. The settlement of Kikori lies on t ...

also splits into a multitude of channels as it crosses the plains close to the Gulf of Papua. The Purari River splits into three major channels as it approaches its mouth.

New Zealand

New Zealand's second-longest river, the Clutha River, splits into two arms, the '' Matau'' and the '' Koua'', some 10 kilometres from the South Island's Pacific Coast. A large island, Inch Clutha, lies between the two arms. Many of the rivers crossing the Canterbury Plains in the central South Island are braided rivers, and several of these split into separate branches before reaching the coast. Notable among these is the Rangitata River, the two arms of which are separated by the low-lying

Rangitata Island Rangitata Island is a long lens-shaped island in the delta of the braided Rangitata River in Canterbury, New Zealand, approximately halfway between Timaru and Ashburton, New Zealand. The island is approximately long and about wide at its w ...

References

Citations

* {{Rivers, streams and springs * River morphology ja:流路形状#派川