Branco River
Template:About Template:Infobox river The Branco River (Template:Langx; Engl: White River) is the principal affluent of the Rio Negro from the north.
Basin
The river drains the Guayanan Highlands moist forests ecoregion.<ref>Template:Citation</ref> 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.<ref name=WDL1>Template:Cite web</ref> 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.<ref name=Quinn2015>Template:Cite book</ref>
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 Template:Convert long, up to its Uraricoera confluence. It has numerous islands, and, Template:Convert 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.<ref name="River Discharge and Reservoir Storage Changes Using Satellite Microwave Radiometry"/>
| Year | Discharge (m3/s) | Year | Discharge (m3/s) | ||||
|---|---|---|---|---|---|---|---|
| Min | Mean | Max | Min | Mean | Max | ||
| 1998 | 5,664 | 16,435 | 2011 | 454 | 5,008 | 16,815 | |
| 1999 | 1,792 | 9,538 | 22,576 | 2012 | 2,135 | 8,381 | 17,944 |
| 2000 | 2,506 | 9,725 | 28,697 | 2013 | 1,377 | 6,493 | 13,229 |
| 2001 | 788 | 6,551 | 17,791 | 2014 | 1,117 | 6,384 | 15,489 |
| 2002 | 1,271 | 5,219 | 18,760 | 2015 | 772 | 3,983 | 10,416 |
| 2003 | 640 | 4,375 | 13,320 | 2016 | 435 | 4,316 | 11,677 |
| 2004 | 756 | 4,244 | 11,959 | 2017 | 2,258 | 7,437 | 16,449 |
| 2005 | 729 | 7,868 | 19,893 | 2018 | 777 | 6,653 | 17,912 |
| 2006 | 2,457 | 9,899 | 22,644 | 2019 | 625 | 5,205 | 15,859 |
| 2007 | 845 | 7,271 | 15,118 | 2020 | 1,567 | 7,216 | 16,564 |
| 2008 | 2,739 | 7,630 | 17,280 | 2021 | 1,712 | 8,828 | 23,180 |
| 2009 | 486 | 4,318 | 10,735 | 2022 | 1,810 | 9,087 | 23,631 |
| 2010 | 278 | 2,754 | 8,040 | 278 | 6,469 | 28,697 | |
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.<ref name=ARussel>The Alfred Russel Wallace page: On the Rio Negro. Template:Webarchive Retrieved 10 October 2017.</ref> It is traditionally considered a whitewater river,<ref>Template:Cite journal</ref><ref>Template:Cite book</ref> although the major seasonal fluctuations in its physico-chemical characteristics makes a classification difficult and some consider it clearwater.<ref name=Villamizar2013>Template:Cite web</ref><ref name=Souza2014>Template:Cite journal</ref> 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.<ref name=ARussel/> Furthermore, its chemistry and color may contradict each other compared to the traditional Amazonian river classifications.<ref name=Villamizar2013/> The Branco River has pH 6–7 and low levels of dissolved organic carbon.<ref name=Souza2014/>
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.<ref name = "Humboldt">Template:Cite web</ref> 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.<ref name=Souza2014/>
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.<ref>Template:Cite book</ref> 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.<ref name=Quinn2015/>
Citations
Notes
References
- Encyclopædia Britannica Online.com: "Branco River" . retrieved 19 September 2009.