Editing Casiquiare canal

{{Short description|River in Venezuela}}
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{{Infobox river
| name               = Casiquiare canal
| native_name        = 
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<!---------------------- IMAGE & MAP -->
| image              = 
| image_size         = 300
| image_caption      = Map of the Cassiquiare canal based on [[Alexander von Humboldt]], 1799 observations
| map                = Casiquiarerivermap.png
| map_size           = 300
| map_caption        = Location of the Casiquiare (highlighted in purple) within the Amazon Basin
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| pushpin_map_size   = 300
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<!---------------------- LOCATION -->
| subdivision_type1  = Country
| subdivision_name1  = [[Venezuela]]
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<!---------------------- PHYSICAL CHARACTERISTICS -->
| length             = {{convert|340|km|mi|abbr=on}}<ref name=fao>{{cite book |last1=Ziesler |first1=R. |last2=Ardizzone |first2=G.D. |title=The Inland waters of Latin America |year=1979 |chapter-url=http://www.fao.org/docrep/008/ad770b/AD770B05.htm |publisher=[[Food and Agriculture Organization|Food and Agriculture Organization of the United Nations]] |isbn=92-5-000780-9 |chapter=Amazon River System |archive-url=https://web.archive.org/web/20141108152358/http://www.fao.org/docrep/008/ad770b/AD770B05.htm |archive-date=8 November 2014 |url-status=live}}</ref>
| width_min          = 
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| depth_min          = 
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| discharge1_location= [[Amazonas (Venezuelan state)|Amazonas]], [[Venezuela]] (near mouth)
| discharge1_min     = 
| discharge1_avg     = {{convert|2,574.3|m3/s|cuft/s|abbr=on}}<ref name="Rivers Network">{{cite web|url=https://www.riversnetwork.org|title=Rivers Network}}</ref>
| discharge1_max     = 
<!---------------------- BASIN FEATURES -->
| source1            = [[Orinoco|Orinoco River]]
| source1_location   = 
| source1_coordinates= {{coord|3|8|18|N|65|52|49|W|display=inline}}
| source1_elevation  = {{convert|110|m|abbr=on}}
| mouth              = [[Rio Negro (Amazon)|Rio Negro]]
| mouth_location     = 
| mouth_coordinates  = {{coord|2|0|5|N|67|5|54|W|display=inline,title}}
| mouth_elevation    = {{convert|79|m|abbr=on}}
| progression        = 
| river_system       = 
| basin_size         = {{convert|42,478|km2|mi2|abbr=on}}<ref name="Rivers Network">{{cite web|url=https://www.riversnetwork.org|title=Rivers Network}}</ref>
| tributaries_left   = 
| tributaries_right  = [[Siapa River|Siapa]], [[Yatua River|Yatua]]
| custom_label       = 
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}}

The '''Casiquiare river''' or '''canal''' ({{IPA|es|kasiˈkjaɾe}}) is a natural [[distributary]] of the upper [[Orinoco]] flowing southward into the [[Rio Negro (Amazon)|Rio Negro]], in [[Venezuela]], South America. As such, it forms a unique natural canal between the Orinoco and [[Amazon Basin|Amazon]] river systems. It is the world's largest river of the kind that links two major river systems, a so-called [[River bifurcation|bifurcation]]. The area forms a [[Drainage divide|water divide]], more dramatically at regional flood stage.

==Etymology==
The name ''Casiquiare'', first used in that form by Manuel Román, likely derives from the [[Ye'kuana language]] name of the river, ''Kashishiwadi''.<ref>Lauer, Matthew Taylor (2005) ''Fertility in Amazonia: Indigenous Concepts of the Human Reproductive Process Among the Ye'kwana of Southern Venezuela'', page 152</ref>

==Discovery==
[[File:Canal do Cassiquiare.jpg|thumb|300px|Casiquiare river or channel, connecting the rivers Orinoco and Negro in the Amazonas forest. The map was drafted based on Alexander von Humboldt 1799 survey of the area.]]
The first European to describe it was Spanish [[Jesuits|Jesuit]] missionary and explorer [[Cristóbal Diatristán de Acuña]] in 1639.

In 1744 a Jesuit priest named Manuel Román, while ascending the [[Orinoco River]] in the region of [[La Esmeralda, Venezuela|La Esmeralda]], met some [[Portugal|Portuguese]] slave-traders from the settlements on the [[Rio Negro (Amazon)|Rio Negro]]. The Portuguese insisted they were not in Spanish territory but on a tributary of the Amazon; they invited Román back with them to prove their claim. He accompanied them on their return, by way of the Casiquiare canal, and afterwards retraced his route to the Orinoco. Along the way, he made [[First contact (anthropology)|first contact]] with the [[Ye'kuana]] people, whom he enlisted to help in his journey. [[Charles Marie de La Condamine]], seven months later, was able to give to the ''[[Académie française]]'' an account of Father Román's voyage, and thus confirm the existence of this waterway, first reported by [[Cristóbal Diatristán de Acuña|Father Acuña]] in 1639.{{sfn|Church|1911a|p=787}}<ref name=Guss>Guss, David. M. (1990) ''To Weave and Sing: Art, Symbol, and Narrative in the South American Rainforest'', page 5</ref>

Little credence was given to Román's statement until it was verified, in 1756, by the [[Spain|Spanish]] Boundary-line Commission of José Yturriaga and [[José Solano y Bote|Solano]].{{sfn|Church|1911a|p=787}} In 1800 German scientist [[Alexander von Humboldt]]<ref name=EB1911Ori>{{cite EB1911 |wstitle=Orinoco |volume=20 |pages=275–276 |first=George Earl |last=Church |author-link=George Earl Church |date=1911b}}</ref> and French botanist [[Aimé Bonpland]] explored the river.<ref>{{ cite book | last=Daum | first=Andreas W.|author-link=Andreas Daum | year=2024 | title=Alexander von Humboldt: A Concise Biography | location=Trans. Robert Savage. Princeton, N.J. | publisher=Princeton University Press |pages=69 | isbn=978-0-691-24736-6 }}</ref> {{citation needed span|During a 1924–25 expedition, [[Alexander H. Rice Jr.]] of [[Harvard University]] traveled up the Orinoco, traversed the Casiquiare canal, and descended the Rio Negro to the Amazon at Manaus. It was the first expedition to use aerial photography and [[shortwave radio]] for mapping of the region.|reason=Rice's WP article indicates he explored the Casiquiare Canal in 1919, and the use of aerial photography and shortwave radio was on a later expedition elsewhere.|date=November 2024}} In 1968 the Casiquiare was navigated by an [[SRN6 hovercraft]] during a [[The Geographical Journal]] expedition.<ref>{{cite news |title= Graham Clarke|url= https://www.telegraph.co.uk/news/obituaries/1565257/Graham-Clarke.html|work= [[The Daily Telegraph]]|date= 2007-10-07|access-date=2008-07-14 }}</ref>

==Geography==
[[File:Rio Orinoco e Canal do Cassiquiare, Venezuela.jpg|thumb|300px|The Casiquiare (bottom left) is separated from the Orinoco]]
The origin of the Casiquiare, at the River Orinoco, is {{convert|9|mi|km|order=flip}} below the mission of [[La Esmeralda, Venezuela|La Esmeralda]] at {{coord|3|8|18.5|N|65|52|42.5|W|region:VE-X_type:landmark|display=inline}}, and about {{convert|123|m|ft}} above sea level. Its mouth at the Rio Negro, an affluent of the [[Amazon River]], is near the town of [[San Carlos de Río Negro|San Carlos]] and is {{convert|91|m|ft}} above sea level.{{sfn|Church|1911a|p=787}}

The general course is south-west, and its length, including windings, is about {{convert|200|mi|km|-1|order=flip}}. Its width, at its [[river bifurcation|bifurcation]] with the Orinoco, is approximately {{convert|300|ft|m|-1|order=flip}}, with a current towards the Rio Negro of {{convert|0.75|mph|m/s|1|order=flip}}. However, as it gains in volume from the very numerous [[tributary]] streams, large and small, that it receives en route, its velocity increases, and in the wet season reaches {{convert|5|mph|m/s|1|order=flip}}, even {{convert|8|mph|m/s|1|order=flip}} in certain stretches. It broadens considerably as it approaches its mouth, where it is about {{convert|1750|ft|m|order=flip|0}} wide. The volume of water the Casiquiare captures from the Orinoco is small in comparison to what it accumulates in its course.{{sfn|Church|1911a|p=787}} Nevertheless, the geological processes are ongoing, and evidence points to a slow and gradual increase in the size of Casiquiare. It is likely that [[stream capture]] is in progress, i.e. what currently is the uppermost Orinoco basin, including [[Cunucunuma River]], eventually will be entirely diverted by the Casiquiare into the Amazon basin.<ref>{{cite book|editor=Quinn, J.A. |editor2=S.L. Woodward | year=2015 | title=Earth's Landscape: An Encyclopedia of the World's Geographic Features | volume=1 | pages=141–142 | isbn=978-1-61069-445-2 | last1=Quinn | first1=Joyce Ann | last2=Woodward | first2=Susan L. }}</ref><ref>{{cite journal |last1=Stokes |first1=Maya |last2=Goldberg |first2=Samuel |last3=Perron |first3=J. Taylor |date=25 May 2018 |title=Ongoing River Capture in the Amazon |journal=Geophysical Research Letters |volume=45 |issue=11 |pages=5545–5552 |doi=10.1029/2018GL078129 |doi-access=free |hdl=1721.1/140798.2 |hdl-access=free }}</ref>

In flood time, it is said to have a second connection with the Rio Negro by a branch, which it throws off to the westward, called the [[Itinivini]], which leaves it at a point about {{convert|50|mi|km|-1|order=flip}} above its mouth. In the dry season, it has shallows, and is obstructed by sandbanks, a few rapids and granite rocks. Its shores are densely wooded, and the soil more fertile than that along the Rio Negro. The general slope of the plains through which the canal runs is south-west, but those of the Rio Negro slope south-east.{{sfn|Church|1911a|p=787}}

The Casiquiare is not a sluggish canal on a flat tableland, but a great, rapid river which, if its upper waters had not found contact with the Orinoco, perhaps by cutting back, would belong entirely to the Negro branch of the Amazon.{{sfn|Church|1911a|p=787}}

To the west of the Casiquiare, there is a much shorter and easier [[portage]] between the Orinoco and Amazon basins, called the isthmus of [[Pimichin]], which is reached by ascending the Temi branch of the [[Atabapo River]], an affluent of the Orinoco. Although the Temi is somewhat obstructed, it is believed that it could easily be made navigable for small craft. The isthmus is {{convert|10|mi|km|0}} across, with undulating ground, nowhere over {{convert|50|ft|m|order=flip|0}} high, with swamps and marshes. In the early 20th century, it was much used for the transit of large canoes, which were hauled across it from the Temi River and reached the Rio Negro by a little stream called the Pimichin.{{sfn|Church|1911a|p=787}}

==Hydrographic divide==
[[File:Atardecer (3080663).jpeg|thumb|300px|Sunset on the Casiquiare River, in the State of Amazonas (Venezuela)]]
The Casiquiare canal – Orinoco River hydrographic divide is a representation of the [[hydrography|hydrographic]] [[water divide]] that delineates the separation between the Orinoco Basin and the [[Amazon Basin]]. (The Orinoco Basin flows west&ndash;north&ndash;northeast into the [[Caribbean Sea|Caribbean]]; the Amazon Basin flows east into the western [[Atlantic Ocean|Atlantic]] in the extreme northeast of [[Brazil]].)

Essentially the river divide is a west-flowing, upriver section of Venezuela's Orinoco River with an outflow to the south into the Amazon Basin. This named outflow is the Casiquiare canal, which, as it heads downstream (southerly), picks up speed and also accumulates water volume.

The greatest manifestation of the divide is during floods. During flood stage, the Casiquiare's main outflow point into the Rio Negro is supplemented by an overflow that is a second, and more minor, entry river bifurcation into the Rio Negro and upstream from its major, common low-water entry confluence with the Rio Negro. At flood, the river becomes an area flow source, far more than a narrow confined river.

The Casiquiare canal connects the upper Orinoco, {{convert|9|mi|km|order=flip}} below the mission of Esmeraldas, with the Rio Negro affluent of the Amazon River near the town of San Carlos.{{sfn|Church|1911a|p=787}}

The simplest description (besides the entire area-floodplain) of the water divide is a "south-bank Orinoco River strip" at the exit point of the Orinoco, also the origin of the Casiquiare canal. However, during the Orinoco's flood stage, that single, simply defined "origin of the canal" is turned into a region, and an entire strip along the southern bank of the Orinoco River.

==See also==
*''[[Crypturellus casiquiare]]'', the barred tinamou.

==References==

===Sources===
*{{EB1911|wstitle=Amazon|volume=1|pages=783–790|first=George Earl|last=Church|author-link=George Earl Church|date=1911a}}
*VARESCHI, Volkmar. ''Orinoco arriba. A través de Venezuela siguiendo a Humboldt''. Caracas: Ediciones Lectura, 1959

===Notes===
{{Reflist}}

==External links==
{{Commons category|Casiquiare River}}
* [https://maps.google.com/maps?f=q&hl=en&q=03%C2%B008%2718.45%22+N+65%C2%B052%2742.51%22+W&ie=UTF8&t=k&om=1&ll=3.138459,-65.878476&spn=0.018255,0.042572 The point where the Casiquiare bifurcates from the Orinoco, on Google Maps]
* [http://www.wikimapia.org/#y=2482133&x=-66423340&z=9&l=0&m=a&v=2 Wikimapia satellite image displaying locations of both the beginning (principio) and the end (desague) of the Casiquiare Canal.]

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{{DEFAULTSORT:Casiquiare Canal}}
[[Category:Orinoco basin]]
[[Category:Tributaries of the Rio Negro (Amazon)]]
[[Category:Rivers of Venezuela]]
[[Category:Biosphere reserves of Venezuela]]
[[Category:River bifurcations]]
[[Category:Rivers of Amazonas (Venezuelan state)]]