Confluence

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Confluence of the Bhagirathi and Alaknanda Rivers to produce the Ganges at Devprayag, India
The same confluence viewed from upstream at a different time; note the swirl of sediment from the Alaknanda.

In geography, a confluence (also: conflux) occurs where two or more flowing bodies of water join together to form a single channel.[1] A confluence can occur in several configurations: at the point where a tributary joins a larger river (main stem); or where two streams meet to become the source of a river of a new name (such as the confluence of the Monongahela and Allegheny rivers at Pittsburgh, forming the Ohio); or where two separated channels of a river (forming a river island) rejoin at the downstream end.

Contrasting water color at confluences[edit]

River confluences often reveal differences in color between the two streams. According to Lynch, "the color of each river is determined by many things: type and amount of vegetation in the watershed, geological properties, dissolved chemicals, sediments and biologic content -- usually algae." Lynch also notes that color differences can persist for miles downstream before they finally blend completely.[2]

Confluences and humankind[edit]

Since rivers often serve as political boundaries, confluences sometimes demarcate three abutting political entities, such as nations, states, or provinces, forming a tripoint. Various examples are found in the list below.

A number of major cities, such as Lyon, Khartoum, and St. Louis, arose at confluences; further examples appear in the list. Within a city, a confluence often forms a visually prominent point, so that confluences are sometimes chosen as the site of prominent public buildings or monuments, as in Koblenz, Lyon, and Winnipeg. Cities also often build parks at confluences, sometimes as projects of municipal improvement, as at Portland and Pittsburgh. In other cases, a confluence is an industrial site, as in Philadelphia or Mannheim. Often a confluence lies in the shared floodplain of the two rivers and nothing is built on it, for example at Manaus, described below.

Notable confluences[edit]

The White Nile and Blue Nile merge at Khartoum; satellite view

Africa[edit]

Asia[edit]

The confluence of the Jialing and the Yangtze in Chongqing. The Yangtze flows left to right across the bottom of the image.
  • The Jialing flows into the Yangtze at Chongqing in China. The confluence forms a focal point in the city, marked by Chaotianmen Square, built 1998.[3] Visitors to the square behold a vast panorama of ships, bridges, skyscrapers, and people.[4]
  • In the Far East, the Amur forms the international boundary between China and Russia. The Ussuri, which also demarcates the border, flows into the Amur at a point midway between Fuyuan in China and Khabarovsk in Russia. The point of the confluence is located in a rural area, part of China, where a commemorative park, Dongji Square, has been built; it features an enormous sculpture representing the Chinese character for "East".[5] The Amur-Ussuri border region was the location of the Sino-Soviet border conflict of 1969; the borderline near the confluence was settled peacefully by treaty in 2008.[6]

Australia[edit]

The Seine becomes a single channel at the west end of the Île de la Cité in Paris. The Pont Neuf can be seen.

Europe[edit]

Seine

  • The Seine divides in the historical center of Paris, flowing around two river islands, the Île Saint-Louis and the Île de la Cité. At the downstream confluence, where the river becomes a single channel again, the Île de la Cité is crossed by the famous Pont Neuf, adjacent to an equestrian statue of King Henri IV and the historically more recent Vert Galant park. The site has repeatedly been portrayed by artists including Monet,[7] Renoir,[8] and Pissarro.[9]
  • Further upstream, the Marne empties into the Seine at Charenton-le-Pont, just southeast of the Paris city limits. The site is dominated by the Huatian Chinagora, a four-star hotel under Chinese management. See Gallery for image.
The Mosel flows into the Rhine at Koblenz.

Rhine

  • The Main River flows into the Rhine just south of Mainz, in Germany (see Gallery below for image).
  • The Mosel flows into the Rhine further north at Koblenz. The name "Koblenz" itself has its origin in the Latin name "Confluentes". In German, this confluence is known as the "Deutsches Eck" ("German corner") and is the site of an imposing monument to German unification featuring an equestrian statue of Kaiser Wilhelm I.
  • Upstream in Switzerland, a small town also named Koblenz (for the same reason) is where the Aare joins the Rhine.

Danube basin

The triple confluence in Passau; from left to right, the Inn, the Danube, and the Ilz.

Other

North America[edit]

The confluence of the Allegheny and Monongahela at Pittsburgh, forming the Ohio
The Ohio flows into the Mississippi at Cairo.
The Rideau Falls in Ottawa, where the Rideau River tumbles into Ottawa River at its mouth.

Mississippi basin

Atlantic watersheds

Pacific watersheds

The confluence of the Rio Negro (black) and the Rio Solimões (turbid) near Manaus, Brazil.

South America[edit]

Confluences not of two rivers[edit]

Confluence of canals
This simplified diagram shows how a section of the Industrial Canal in New Orleans also serves as the channel for the Gulf Intracoastal Waterway and the Mississippi River-Gulf Outlet Canal. At the bottom, a portion of the Intracoastal is also shown to be "confluent" with the Mississippi River.

Occasionally "confluence" is used to describe the meeting of tidal or other non-riverine bodies of water, such as two canals[11] or a canal and a lake.[12] A one-mile (1.6 km) portion of the Industrial Canal in New Orleans accommodates the Gulf Intracoastal Waterway and the Mississippi River-Gulf Outlet Canal; therefore those three waterways are confluent there.

The term confluence also applies to the merger of the flow of two glaciers.[13] For sample images, see Gallery below.

Gallery[edit]

All images can be expanded by clicking on them, and are discussed in the list given above.

See also[edit]

External links[edit]

  • [8] A collection of full-size, vivid photographs of confluences, most of them mentioned in the list above.

References[edit]

  1. ^ "Conflux - Definition of conflux by Merriam-Webster". merriam-webster.com. 
  2. ^ David Lynch (2014) "The Confluence of Rivers"; Earth Science Picture of the Day, at [1].
  3. ^ http://www.topchinatravel.com/china-attractions/chaotianmen-square.htm
  4. ^ See pictorial coverage at Google Maps: [2]
  5. ^ See Bruno Maçães, "Signs and Symbols on the Sino-Russian Border", published in The Diplomat. On line at [3].
  6. ^ See [4].
  7. ^ See [5] for image.
  8. ^ See [6].
  9. ^ See [7].
  10. ^ Kogovšek, Janja; Petrič, Metka; Zupan Hajna, Nadja; Pipan, Tanja. "Planinska jama" [Planina Cave]. In Šmid Hribar, Mateja; Golež, Gregor; Podjed, Dan; Kladnik, Drago; Erhartič, Bojan; Pavlin, Primož; Ines, Jerele. Enciklopedija naravne in kulturne dediščine na Slovenskem [Encyclopedia of Natural and Cultural Heritage in Slovenia] (in Slovenian). Retrieved 17 May 2012. 
  11. ^ The U.S. Army Corps of Engineers refers to the confluence of the Assawoman Canal with the Bethany Loop Canal in Delaware. See: "CENAP-OP-R-Quarterly Report, 2004-05-12". Philadelphia Engineer District. Retrieved 2006-03-11. 
  12. ^ Engineers in New Orleans refer to the confluence of the 17th Street Canal and Lake Pontchartrain. See: "Interim Closure Structure at 17th St. Canal". Task Force Guardian. Archived from the original on 2006-06-25. Retrieved 2006-03-11. 
  13. ^ Vladimir Kotlyakov and Anna Komarova (2006) Elsevier's Dictionary of Geography: in English, Russian, French, Spanish and German. Elsevier. Passage cited may be accessed on Google Books.