Orinoco

Water Map of the Orinoco River basin (see correction instructions)

Bridge over the Orinoco River at Ciudad Bolívar, Venezuela ( 2004)

The Orinoco is equipped with a water flow of 35,000 m³ / s, the fourth largest river in the world and the second largest in South America. There the flow is, however, in terms of its length (from the headwaters of the Río Guaviare ) is the Orinoco River system than 2010 km and about 3010 km, equal to three streams exceeded (Amazonas, Paraná, Rio São Francisco). The still high volume of the Orinoco is explained by the high rainfall in almost the entire, comprehensive about one million square kilometers of catchment area ranging from 1000 mm / yr to about 4000 mm / yr. The river basin lies just north of the equator, is partially framed by the Andes and other mountain ranges (Sierra Nevada del Cocuy: 5330 m) and covered by tropical rainforest and wet savannas. It lies about two-thirds on Venezuelan territory and about one-third on the Columbia.

Course

The headwaters of the Orinoco located in the southwestern highlands of Guiana in the Sierra Parima in the Venezuelan state of Amazonas, near the border of the Brazilian state of Amazonas. His subsequent course describes a wide, sweeping westward arc around the Guiana Shield around northward to the Atlantic. Usually four sections can be distinguished:

Alto Orinoco

For this Paragua also mentioned, generally west-northwest -directed upper barrel section, there are lengths to (800 km from 710 km to 850 km are plausible ). The Orinoco rises in only 1,047 meters at the Cerro Delgado Chalbaud and then flows through the mainly by steep hilly highlands of Guiana in alternating narrow and basin -shaped valley portions. They are at some distance from the rock walls prominent mesas up to 2000 meters above projects such as the Cerro Duida near the former mission station Esmeralda.

The bottom here is part of a network of Talsandebenen, which is penetrated by individual granitic hills and rock formations. The Orinoco leads to the confluence sediment- rich tributaries from the higher mountains cloudy water and forms here at its ramifications not only islands, but also - in headwaters of rivers very rare - Flussbifurkation; it is considered the most important river branching world. The Brazo Casiquiare attracts the waters of the Orinoco ( 1400 m³ / s) between 12% at low water and more than 25 % at high water and grows in the course to the left source of the Rio Negro, which in turn flows into the Amazon. The Alto Orinoco then gets down river again increasingly features of a blackwater river.

The uppermost part is one of the verkehrsfernsten parts of South America and is settlement of the indigenous Yanomamo people. Large parts of the area are under the protection of the largest Venezuelan National Parks Parima Tapirapeco and the National Park Duida - Marahuaca. At a branched rapids river flows from the right of the Río Ventuari provided with a water supply of more than 2,000 m³ / s the Orinoco doubled ( Rhine at Emmerich: about 2,330 m³ / s).

Medio Orinoco

The middle section of the river begins with the mouth of the Orinoco largest tributary, the springing in the Colombian Andes Río Guaviare. It exceeds the upper Orinoco not only significantly in length ( approximately 1760 km ), but also on water management ( 7,400 m³ / s, including the recently introduced resulted Río ATABAPO, compared to 4,750 m³ / s of the Orinoco ). Not without reason is therefore made it (often from Colombian side ) that the Guaviare is the main stream of the Orinoco River system, which (according to other sources 2560-2800 miles) reached with him a length of around 3,000 kilometers.

This confluence of the section of the Orinoco, on the flow unto it from the left in quick succession tributaries from the Andes begins. In addition, it forms over a length of 270 kilometers, to the confluence of its third largest tributary, the Río Meta, the border between Venezuela and Colombia. This section also contains the largest rapids on the Orinoco, after 145 kilometers the Raudales de Maipures, after another 55 kilometers, the Raudales de Atures. The town of Puerto Ayacucho below the rapids is the upper endpoint of the continuous navigation path on the Orinoco. A bit further down opens the Río Meta; he is much further upstream navigable and therefore the more important traffic route. To some extent, already spoken of the lower Orinoco from here, but partly only from the mouth of the Río Apure, which concludes the series of Andean tributaries. The Orinoco is here to become a lehmgelben white water river.

Bajo Orinoco

The beginning of the lower Orinoco is marked by the still (2010) under construction bridge Puente between Mercosur and Caicara Cabruta. The stream here has a water flow of 22,250 m³ / s

In the last race of the Orinoco receives its tributaries again mainly from the right side, from the very rainy highlands of Guyana. In the catchment area of ​​4,800 m³ / s second largest Orinoco tributary, the river Caroní, is the highest waterfall in the world, Angel Falls, and the Caura River, the other major tributary of the lower Orinoco, forms with the Salto Pará the most powerful waterfall in Venezuela. The rivers from the mountains of Guayana are again mostly dark colored ( by tannins from plant residues and humic acids ).

The population density is much higher than above in this section; here are the two major cities of Ciudad Bolívar ( the oldest bridge over the Orinoco, the Puente de Angostura ) and Barcelona at the mouth of Caroní ( with the Puente Orinoquia ). Until Ciudad Bolívar, with its significant Erzveradeanlagen in Puerto Ordaz and Palua ocean-going vessels can ascend the Orinoco.

Orinoco Delta

The estuary is one of the world's largest with an area of ​​about 19,000 square kilometers and a width of 370 kilometers. By far the most important tributary, the Rio Grande flows to the east; the westernmost Stromarm, the Río Mañano, was forwarded by the Volcan Dam largely the Caño Macareo, the central main arm. Other interventions with risks to the habitats of the species- rich amphibian delta landscape brings the development of local oil reserves with it. The delta is inhabited by the people of the Warao.

A term for their language course for paddling (boot area) to have been borrowed from the name Orinoco.

Nature Spatial development of the river system

The course of the river Orinoco could evolve its present form only after the Andes had begun to unfold in front of the westward drifting, much older continental nuclei ( cratons ) South America or to raise en bloc. The northern part of the craton, the Guiana Shield, bulges since the beginning of the Tertiary on over today's lowlands of the Amazon and Orinoco. Originally it still separated by a sea that connected the upper Amazon basin for a while with today's Caribbean Sea, by the young Andean chains with their often little solidified rocks. From there the rivers filled with extensive alluvial fans on the inlet and collect since then along the line where the alluvial fans against the heaving Guiana Shield encounter. This leading around to the base of the bulge drainage line represents the present arcuate course of the Orinoco

The Guiana Shield is overlain by also very old and resistant sandstones whose insular remnants tower over the hills as striking mesas. For these rocks, the rivers can dissipate only a little material, so they, in contrast to the strong sediments leading Andean tributaries, have the character of clear water rivers or black water rivers. The river networks in the Guiana Shield reflect, often with abrupt changes of direction often resist paths of former drainage directions.

The same applies to the headwaters of the Río ATABAPO ( tributary of the Río Guaviare, the valley line of the middle Orinoco upward continuing ), the former headwaters has been lost to the source river Guainía of Río Negro and has left it a dry valley. It is known as the Isthmus del Pimichin as an alternative connection between the Amazon and Orinoco (formerly Boat Transport, parallel gravel road).

The annual rainfall in the Orinoco take of about 3,600 mm in the south to about 1000 mm at the root from Delta, and then increase again to 2,400 mm on the short distance to the coast. In perhumiden climate of southern Orinocobeckens tropical rain forests dominate with few open islands, to the north is wide grasslands of the humid savannah extend.

Exploration of the Orinoco

The first map in which the Orinoco was located, dates back to 1529 and dates back to Diego Ribeiro. But it was only in the 18th century, the first great expedition under the leadership of José Solano took place. From the upper Orinoco they penetrated to the Rio Negro.

1800 took the German explorer Alexander von Humboldt and Aimé Bonpland, the French botanist on an expedition from the mouth of the Río Apure to the upper Orinoco Valley. They collected important data on the flora and fauna of the river basin. The data authorized by today and has always been contemplated vesting of the Río Guaviare to the rank of major hydrological flow Humboldt presented here as an expression of " geographical ignorance " long lasting effect denied. Nevertheless, Humboldt was the one who took the existence of Flussbifurkation first and could explain the hydrological peculiarities of the Orinoco understandable.

The source of the Orinoco was found in November 1951 by Venezuelan and French researchers.

Reception

The national colored, still not entirely enclosed dispute over Hauptquellast of the Orinoco is already being addressed by Jules Verne.

The width of the river reflects the song Orinoco Flow by Enya, which came in some charts in 1988 at # 1.