The Branco River ( pt, Rio Branco; Engl: ''White River'') is the principal Tributary, affluent of the Rio Negro (Amazon), Rio Negro from the north.
Basin
The river drains the Guayanan Highlands moist forests ecoregion.
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 River, Uraricoera and the Takutu River, Takutu.
The latter almost links its sources with those of the Essequibo River, 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.
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 long, up to its Uraricoera confluence. It has numerous islands, and, above its mouth, it is broken by a bad series of rapids.
Discharge
Average, minimum and maximum discharge of the Branco River at near mouth. Period from 1998 to 2022.
Water chemistry
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]
On the Rio Negro.
Retrieved 10 October 2017. It is traditionally considered a Whitewater river (river type), whitewater river, although the major seasonal fluctuations in its physico-chemical characteristics makes a classification difficult and some consider it Clearwater river (river type), clearwater.
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 Amazon basin, 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.][
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River capture
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.[
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Citations
Notes
References
Encyclopædia Britannica Online.com: "Branco River"
. retrieved 19 September 2009.
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Rivers of Roraima
Tributaries of the Rio Negro (Amazon)
Boa Vista, Roraima
Guayana Highlands