Branco River

The river drains the Guayanan Highlands moist forests ecoregion.{{citation|title=South America: Southern Venezuela, northern Brazil, western Guyana, and eastern Colombia (NT0124)|publisher=WWF: World Wildlife Fund|last=Sears|first=Robin|url=http://www.worldwildlife.org/ecoregions/nt0124|access-date=2017-04-01|archive-date=2020-09-22|archive-url=https://web.archive.org/web/20200922120359/https://www.worldwildlife.org/ecoregions/nt0124|url-status=live}}

It is enriched by many streams from the Tepui highlands which separate Venezuela and Guyana from Brazil. Its two upper main tributaries are the Uraricoera and the Takutu.{{cite web|title=Map of the Branco or Parimé River and of the Caratirimani Uararicapará Majari, Tacutú and Mahú Rivers|url=http://www.wdl.org/en/item/816|publisher=World Digital Library|access-date=27 April 2013|archive-date=14 December 2013|archive-url=https://web.archive.org/web/20131214135611/http://www.wdl.org/en/item/816/|url-status=live}} The latter almost links its sources with those of the Essequibo; during floods headwaters of the Branco and those of the Essequibo are connected, allowing a level of exchange in the aquatic fauna (such as fish) between the two systems.{{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 | page=142 |publisher=Bloomsbury Academic | isbn=978-1-61069-445-2 }}

File:Gaiola Anacorda, Branco River, Acre River, 1912.jpg

The Branco flows nearly south, and finds its way into the Negro through several channels and a chain of lagoons similar to those of the latter river. It is {{convert|350|mi|km}} long, up to its Uraricoera confluence. It has numerous islands, and, {{convert|235|mi|km}} above its mouth, it is broken by a bad series of rapids.

Average, minimum and maximum discharge of the Branco River at near mouth. Period from 1998 to 2022.

As suggested by its name, the Branco (literally "white" in Portuguese) has whitish water that may appear almost milky due to the inorganic sediments it carries.The Alfred Russel Wallace page: [http://people.wku.edu/charles.smith/wallace/S011.htm On the Rio Negro.] {{Webarchive|url=https://web.archive.org/web/20150602232906/http://people.wku.edu/charles.smith/wallace/S011.htm |date=2015-06-02 }} Retrieved 10 October 2017. It is traditionally considered a whitewater river,{{cite journal | author1=Venticinque |author2=Forsberg |author3=Barthem |author4=Petry |author5=Hess |author6=Mercado |author7=Cañas |author8=Montoya |author9=Durigan |author10=Goulding |display-authors=3 | year=2016 | title=An explicit GIS-based river basin framework for aquatic ecosystem conservation in the Amazon | journal=Earth Syst. Sci. Data | volume=8 |issue=2 | pages=651–661 | doi=10.5194/essd-8-651-2016 |bibcode=2016ESSD....8..651V |doi-access=free }}{{cite book| editor1=Val, A.L.|editor2=V.M.F. de Almeida-Val|editor3=D.J. Randall | year=2013 | title=Fish Physiology: The Physiology of Tropical Fishes | page=27 | isbn=978-0-12350-445-6 }} although the major seasonal fluctuations in its physico-chemical characteristics makes a classification difficult and some consider it clearwater.{{cite web |author1=Ríos-Villamizar, E.A. |author2=M.T.F. Piedade |author3=J.G. da Costa |author4=J.M. Adeney |author5=J. Junk |year=2013 |title=Chemistry of different Amazonian water types for river classification: A preliminary review |url=https://www.researchgate.net/publication/271427552 |access-date=2017-12-11 |archive-date=2021-02-14 |archive-url=https://web.archive.org/web/20210214122732/https://www.researchgate.net/publication/271427552_Chemistry_of_different_Amazonian_water_types_for_river_classification_A_preliminary_review |url-status=live }}{{cite journal | author1=de Souza kodra, A. |author2=M.N. Fernandes |author3=W.L. Paxiúba Duncan | year=2014 | title=Effect of clearwater on osmoregulation of cururu ray, Potamotrygon sp. (Chondrichthes; Potamotrogonidae), an endemic species from blackwater river | journal=Scientia Amazonia | volume=3 | issue=1 | pages=15–24 }} Especially the river's upper parts at the headwaters are clear and flow through rocky country, leading to the suggestion that sediments mainly originate from the lower parts. Furthermore, its chemistry and color may contradict each other compared to the traditional Amazonian river classifications. The Branco River has pH 6–7 and low levels of dissolved organic carbon.

Alfred Russel Wallace mentioned the coloration in "On the Rio Negro", a paper read at the 13 June 1853 meeting of the Royal Geographical Society, in which he said: "[The Rio Branco] is white to a remarkable degree, its waters being actually milky in appearance". Alexander von Humboldt attributed the color to the presence of silicates in the water, principally mica and talc.{{cite web| url = http://ebooks.adelaide.edu.au/h/humboldt/alexander/travels/chapter25.html| title = Alexander von Humboldt, Personal Narrative of Travels to the Equinoctial Regions of America During the Years 1799-1804, (chapter 25). Henry G. Bohn, London, 1853.| access-date = 2015-05-13| archive-date = 2016-03-03| archive-url = https://web.archive.org/web/20160303230636/https://ebooks.adelaide.edu.au/h/humboldt/alexander/travels/chapter25.html| url-status = dead}} There is a visible contrast with the waters of the Rio Negro at the confluence of the two rivers. The Rio Negro is a blackwater river with dark tea-colored acidic water (pH 3.5–4.5) that contains high levels of dissolved organic carbon.

Until approximately 20,000 years ago the headwaters of the Branco River flowed not into the Amazon, but via the Takutu Graben in the Rupununi area of Guyana towards the Caribbean.{{Cite book|url=http://urlib.net/8JMKD3MGP3W34P/3LSDRJB|title=Evolução quaternária do Rio Branco - norte da Amazônia - com base em dados orbitais e geológicos.|last=Cremon|first=É. H.|year=2016|publication-place=Tese (Doutorado em Sensoriamento Remoto) - Instituto Nacional de Pesquisas Espaciais (INPE), São José dos Campos}} Currently in the rainy season much of the Rupununi area floods, with water draining both to the Amazon (via the Branco River) and the Essequibo River.

{{reflist|24em}}

• [http://www.britannica.com/EBchecked/topic/77606/Branco-River Encyclopædia Britannica Online.com: "Branco River"] . retrieved 19 September 2009.

{{Commons category|Rio Branco (Rio Negro tributary)}}

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Category:Rivers of Roraima

Category:Tributaries of the Rio Negro (Amazon)

Category:Boa Vista, Roraima

Category:Guayana Highlands