Rio Negro (Amazon)

Rio Negro in Brazil

The position and course of the Rio Negro

The east-west course of the Amazon with the dark Rio Negro ( above) in the satellite image

The Rio Negro (Spanish: Río Negro; port. and span for " Black River " ) is equipped with a water flow of approximately 28,400 m³ / s and a length of 2,253 kilometers ( with Rio Uaupés 2400 km ) after the Rio Madeira is the second largest tributary the world. Although it occupies only 60 square of the longest rivers of the earth, lead only six rivers more water than he. Its headwaters located in the southwest of the hill country of Guyana. The Rio Negro flows, traversing the Equator, southeasterly direction through Brazil and empties below Manaus in the Amazon.

River

Headwaters

The Rio Negro is formed from the confluence of the headwaters of the Río Guainía, which is regarded as the headwaters of the Río Negro since 1884, and the Río Casiquiare, by the northward branches as Brazo Casiquiare by Venezuela flowing upper Orinoco and the most significant milestone Flussbifurkation Earth forms.

The source region of the Río Guainía located in the southeast of Colombia in the province Guainía, from where he initially flows east to ease in later to the south and to form the border of Colombia and Venezuela. The river basin is very rich in precipitation and sparsely populated. The river is low cut in the granites and migmatites of the hilly here Guiana Shield. Occasionally the uppermost Río Negro to the border to Brazil also known as Río Guainía.

The Río Casiquiare branches with a water flow of about 250 m³ / s from the area of ​​a large alluvial fan from the upper Orinoco. Many, especially coming from the left tributaries let the first only about 100 meters wide river grow quickly. The largest is the rapids rich Río Siapa (also Shukuminakëu "River of budgies ") with a length of over 410 kilometers in length. This clear water river carries more water at the mouth and can be taken as Hauptquellast the Río Casiquiare in terms of water volume. He is known as the settlement area of indigenous peoples such as the Yanomamo and also for its rich variety of aquatic fauna. In the catchment area of the second largest tributary, the river Pacimoni, there is another bifurcation that creates a water connection directly to the middle Rio Negro.

In San Carlos de Rio Negro, even in Venezuela, but close to the borders with Colombia and Brazil, to Rio and Rio Guainía Casiquiare unite the Rio Negro.

Both source rivers appear to be approximately equal.

Course as Rio Negro

The Rio Negro flows the next kilometers south and crossed the border to Brazil and the state of Amazonas. The opening of the 1375 km long Rio Uaupés at the equator can be almost exactly the Rio Negro record whose eastern direction of flow. The Rio Uaupés has taken another path to the mouth, but is surpassed in water supply from the Rio Negro. After the confluence of power, especially above São Gabriel da Cachoeira forms ( Portuguese: cataract ), numerous rapids. Approximately 200 km downstream 250 km before Manaus slowed, and branches out of the Rio Negro. The current reaches a width of about 20 kilometers and passes through the national park Jau an extensive flood plains, a consequence of the backlog by the below -lying sediment compartments of the leading- here Rio Branco ( White Water River ), where the Rio Negro narrowed to barely 1.5 km width. Then, the current turns to the southeast and it gradually expands again to about 27 kilometers width, interspersed with islands and levees of Anavilhanas archipelago, this time caused by the backflow of highly sediments depositing Amazon. In Manaus, the river is concentrated by high banks along 2.7 kilometers wide and crossed by the nearly 3,600 -meter-long Ponte Rio Negro. Near the southern suburbs of Manaus, the Rio Negro joins the Amazon, the (known as Encontro das Aguas ) leads within Brazil up to this junction the name Rio Solimões.

Black water

The Rio Negro appears because of its high content of humic and fulvic acids, the ( 720,114 km ²) have been washed from the already heavily leached, sandy soils of the terra firme rain in its catchment area, black (black water river). Black water is indeed highly colored, but transparent, because it contains no particles. In the nutrient-poor waters almost no plants grow, yet many dead plants get there and decompose. Due to the lack of nutrients are in the Rio Negro hardly mosquito larvae and therefore practically no malaria. In the upper reaches of the Rio Negro receives from the Guiana Shield and clear water rivers. Below the confluence of the Rio Branco, the water is turbid and brownish.

After the junction of the Rio Negro its black water can be distinguished more than 30 kilometers from the milky - brown waters of the Amazon.

Headwaters and largest tributaries

The Rio Negro has two source rivers:

  • Right frontal flow: Río Guainía Right tributary Río Aquio
  • Left tributary of Río Conorochite
  • Left tributary of Río Siapa
  • Left tributary of Río Pasimoni

One of the largest tributaries of the Rio Negro ( from the confluence of the two sources ) include ( downstream ):

  • Rio Xie
  • Rio Icana
  • Rio Uaupés
  • Rio Curicuriari
  • Rio Marié
  • Rio Tea
  • Rio Urubaxi
  • Rio Ararirá
  • Rio Cuiuni
  • Rio Caures
  • Rio Unini
  • Rio Jaú
  • Rio Padurari
  • Rio Cauaburi
  • Rio Marauiá
  • Rio Padauiri
  • Rio Demini
  • Rio Jufari
  • Rio Branco
  • Rio Jauaperi
  • Rio Camananaú
  • Rio Apuaú
  • Rio Cuieiras
Amazon River Casiquiare canal Meeting of Waters Branco River Town Municipality Madeira River Amazonas (Brazilian state) Manaus Iranduba Bridge Congo River Rand McNally
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