Junction of the Yukon and Koyukuk Rivers, Alaska

An anabranch is a section of a

river A river is a natural flowing watercourse, usually freshwater, flowing towards an ocean, sea, lake or another river. In some cases, a river flows into the ground and becomes dry at the end of its course without reaching another body of wate ...

stream A stream is a continuous body of water, body of surface water Current (stream), flowing within the stream bed, bed and bank (geography), banks of a channel (geography), channel. Depending on its location or certain characteristics, a stream ...

that diverts from the main

channel Channel, channels, channeling, etc., may refer to: Geography * Channel (geography), in physical geography, a landform consisting of the outline (banks) of the path of a narrow body of water. Australia * Channel Country, region of outback Austral ...

stem Stem or STEM may refer to: Plant structures * Plant stem, a plant's aboveground axis, made of vascular tissue, off which leaves and flowers hang * Stipe (botany), a stalk to support some other structure * Stipe (mycology), the stem of a mushro ...

of the

watercourse A stream is a continuous body of surface water flowing within the bed and banks of a channel. Depending on its location or certain characteristics, a stream may be referred to by a variety of local or regional names. Long large streams are ...

and rejoins the main stem downstream. Local anabranches can be the result of small islands in the watercourse. In larger anabranches, the flow can diverge for a distance of several kilometers before rejoining the main channel.

Word usage and related terms

The term ''anabranch'', in its

hydrological Hydrology () is the scientific study of the movement, distribution, and management of water on Earth and other planets, including the water cycle, water resources, and environmental watershed sustainability. A practitioner of hydrology is calle ...

meaning, is used more frequently in

Australia Australia, officially the Commonwealth of Australia, is a Sovereign state, sovereign country comprising the mainland of the Australia (continent), Australian continent, the island of Tasmania, and numerous List of islands of Australia, sma ...

than in the rest of the English-speaking world. The term ''anabranching river'' describes a

with many anabranches, whilst an anastomosing river is an organic-rich subset of this

type. The term

braided river A braided river, or braided channel, consists of a network of river channels separated by small, often temporary, islands called braid bars or, in English usage, ''aits'' or ''eyots''. Braided streams tend to occur in rivers with high sediment l ...

describes

s which are divided by small

islands An island (or isle) is an isolated piece of habitat that is surrounded by a dramatically different habitat, such as water. Very small islands such as emergent land features on atolls can be called islets, skerries, cays or keys. An island ...

into multiple channel threads within a single main channel, but the term does not describe the multiple channels of an anabranching river. A

distributary 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 distributar ...

is a branch of a

that does not rejoin the main channel; these are common on and near

river delta A river delta is a landform shaped like a triangle, created by deposition (geology), deposition of sediment that is carried by a river and enters slower-moving or stagnant water. This occurs where a river enters an ocean, sea, estuary, lake, res ...

s. A

bayou In usage in the Southern United States, a bayou () is a body of water typically found in a flat, low-lying area. It may refer to an extremely slow-moving stream, river (often with a poorly defined shoreline), marshy lake, wetland, or creek. They ...

is often an anabranch. An anabranch that gets cut off from the main channel becomes an

oxbow lake An oxbow lake is a U-shaped lake or pool that forms when a wide meander of a river is cut off, creating a free-standing body of water. In South Texas, oxbows left by the Rio Grande are called '' resacas''. In Australia, oxbow lakes are call ...

, known in Australia as a

billabong Billabong ( ) is an Australian term for an oxbow lake, an isolated pond left behind after a river changes course. Billabongs are usually formed when the path of a creek or river changes, leaving the former branch with a dead end. As a result ...

Examples

* The

Magdalena River The Magdalena River ( es, Río Magdalena, ; less commonly ) is the main river of Colombia, flowing northward about through the western half of the country. It takes its name from the biblical figure Mary Magdalene. It is navigable through much of ...

, in Colombia, bifurcates in

El Banco El Banco (literally meaning River bank in Spanish) is a Colombian Municipality and town located in the southernmost part of the Magdalena Department by the Magdalena River. Climate El Banco has a tropical monsoon climate An area of tropical m ...

in two branches: Brazo de Loba (Shewolf Branch in Spanish) and Brazo de Mompox. The first one, Brazo de Loba is the main navigable channel and is 177 km long. Brazo de Mompox is thus the anabranch. There are several other branches that join those two main branches, interconnected by swamps ("ciénagas"), the main ones being Quitasol, Chicagua and La Victoria. Between Brazo de Loba and Brazo de Mompox is the island of Mompox or Margarita Island, a sunken geological block of 2.200 square km between the faults of Chicagua and El Romeral. * In the

Fraser River The Fraser River is the longest river within British Columbia, Canada, rising at Fraser Pass near Blackrock Mountain in the Rocky Mountains and flowing for , into the Strait of Georgia just south of the City of Vancouver. The river's annual d ...

delta of

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

Canada Canada is a country in North America. Its ten provinces and three territories extend from the Atlantic Ocean to the Pacific Ocean and northward into the Arctic Ocean, covering over , making it the world's second-largest country by tot ...

North Arm Fraser River North is one of the four compass points or cardinal directions. It is the opposite of south and is perpendicular to east and west. ''North'' is a noun, adjective, or adverb indicating direction or geography. Etymology The word ''north'' is ...

Middle Arm Fraser River Middle or The Middle may refer to: * Centre (geometry), the point equally distant from the outer limits. Places * Middle (sheading), a subdivision of the Isle of Man * Middle Bay (disambiguation) * Middle Brook (disambiguation) * Middle Creek ( ...

, and

South Arm Fraser River South is one of the cardinal directions or compass points. The direction is the opposite of north and is perpendicular to both east and west. Etymology The word ''south'' comes from Old English ''sūþ'', from earlier Proto-Germanic ''*sunþaz ...

each fall into

Georgia Strait The Strait of Georgia (french: Détroit de Géorgie) or the Georgia Strait is an arm of the Salish Sea between Vancouver Island and the extreme southwestern mainland coast of British Columbia, Canada and the extreme northwestern mainland coast ...

separately. On the other hand,

Annacis Island Annacis Island is a narrow island under the jurisdiction of City of Delta in Lower Mainland, British Columbia, located just downstream of the south arm of the Fraser River bifurcation between Lulu Island to the north and the Delta peninsula to t ...

splits (South Arm) Fraser River into the (main)

Annieville Channel North Delta (founded as Annieville) is a largely middle-class commuter town situated in the Lower Mainland, of British Columbia, Canada. The community is the most populous of the three communities (North Delta, Ladner, and Tsawwassen) that make ...

and the (smaller) Annacis Channel, which rejoin below the island. * In western

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 ...

the Great Darling Anabranch is the ancestral path of the

Darling River The Darling River ( Paakantyi: ''Baaka'' or ''Barka'') is the third-longest river in Australia, measuring from its source in northern New South Wales to its conflu ence with the Murray River at Wentworth, New South Wales. Including its longes ...

, dividing south of

Menindee Menindee (frequently but erroneously spelled "Menindie" ) is a small town in the far west of New South Wales, Australia, in Central Darling Shire, on the banks of the Darling River, with a sign-posted population of 980 and a population of 551. ...

and extending for 460 km before joining the

Murray River The Murray River (in South Australia: River Murray) (Ngarrindjeri: ''Millewa'', Yorta Yorta: ''Tongala'') is a river in Southeastern Australia. It is Australia's longest river at extent. Its tributaries include five of the next six longest r ...

. The anabranch contains flowing water only in wetter years. * In the Lower Simpson Desert, in

South Australia South Australia (commonly abbreviated as SA) is a state in the southern central part of Australia. It covers some of the most arid parts of the country. With a total land area of , it is the fourth-largest of Australia's states and territories ...

, Kallakoopah Creek is an anabranch of the

Warburton River The Warburton River (or Warburton Creek) is a freshwater stream in the far north of South Australia that flows in a south westerly direction and discharges into the eastern side of Lake Eyre. It is one of the state's largest rivers, and is part ...

that flows during major Warburton floods of over 5 m in depth. The Kallakoopah is approximately 400 km long and members of the Lake Eyre Yacht Club and others have used it to sail a circular route to

Lake Eyre Lake Eyre ( ), officially known as Kati Thanda–Lake Eyre, is an endorheic lake in east-central Far North South Australia, some north of Adelaide. The shallow lake is the depocentre of the vast endorheic Lake Eyre basin, and contains the ...

by traveling down the Kallakoopah and returning via the Warburton. * The Bahr el Zeraf in southern

Sudan Sudan ( or ; ar, السودان, as-Sūdān, officially the Republic of the Sudan ( ar, جمهورية السودان, link=no, Jumhūriyyat as-Sūdān), is a country in Northeast Africa. It shares borders with the Central African Republic t ...

splits from the Bahr al Jabal section of the

White Nile The White Nile ( ar, النيل الأبيض ') is a river in Africa, one of the two main tributaries of the Nile, the other being the Blue Nile. The name comes from the clay sediment carried in the water that changes the water to a pale color. ...

and flows for 240 km (150 mi), before rejoining the White Nile proper upriver from

Malakal Malakal is a city in South Sudan. It is the capital of Upper Nile State, South Sudan, along the White Nile River. It also serves as the headquarter of Malakal county and it used to be the headquarter of Upper Nile Region from 1970s to late 1990s. ...

. * Approximately 15 km out of

Charters Towers Charters Towers is a rural town in the Charters Towers Region, Queensland, Australia. It is by road south-west from Townsville on the Flinders Highway. During the last quarter of the 19th century, the town boomed as the rich gold deposits under ...

(

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_ ...

) is a section of the

Burdekin River The Burdekin River is a river located in North and Far North Queensland, Australia. The river rises on the northern slopes of Boulder Mountain at Valley of Lagoons, part of the western slope of the Seaview Range, and flows into the Coral Sea a ...

known as 'the anabranch'. This strip of water is separate from the main flood way, and is typically dry during the sunnier months. Once there is consistent rain, it will meet up with the river again and flood with fresh water. It is well known for barramundi fishing. * Probably because waterways played an important role in infrastructure, anabranches and the resulting river islands are often found in old cities as with the

Île de la Cité Île de la Cité (; English: City Island) is an island in the river Seine in the center of Paris. In the 4th century, it was the site of the fortress of the Roman governor. In 508, Clovis I, the first King of the Franks, established his palace ...

in Paris.

References

{{Authority control Fluvial landforms Rivers Water streams Geomorphology