Orinoco

For other uses, see Orinoco (disambiguation).
Orinoco River
Río Orinoco
Countries Colombia, Venezuela
District South America
Source
 - location Cerro Delgado-Chalbaud, Parima Mountains, Venezuela
 - elevation 1,047 m (3,435 ft)
 - coordinates 02°19′05″N 63°21′42″W / 2.31806°N 63.36167°W / 2.31806; -63.36167
Mouth Delta Amacuro
 - location Atlantic Ocean, Venezuela
 - elevation 0 m (0 ft)
 - coordinates 8°37′N 62°15′W / 8.617°N 62.250°W / 8.617; -62.250Coordinates: 8°37′N 62°15′W / 8.617°N 62.250°W / 8.617; -62.250 [1]
Length 2,140 km (1,330 mi)
Basin 880,000 km2 (339,770 sq mi)
Discharge
 - average 33,000 m3/s (1,165,384 cu ft/s)
Orinoco's watershed

The Orinoco is one of the longest rivers in South America at 2,140 kilometres (1,330 mi). Its drainage basin, sometimes called the Orinoquia, covers 880,000 square kilometres (340,000 sq mi), with 76.3 percent of it in Venezuela and the remainder in Colombia. The Orinoco and its tributaries are the major transportation system for eastern and interior Venezuela and the llanos of Colombia. The Orinoco is extremely diverse and hosts a wide variety of flora and fauna.

History

Map of Lower Orinoco 1897

The mouth of the Orinoco at the Atlantic Ocean was documented by Columbus on 1 August 1498, during his third voyage. Its source at the Cerro Delgado-Chalbaud, in the Parima range, was not explored until 1951, 453 years later. The source, near the Venezuelan-Brazilian border, at 1,047 metres (3,435 ft) above sea level (02°19′05″N 63°21′42″W / 2.31806°N 63.36167°W / 2.31806; -63.36167 ), was explored in 1951 by a joint Venezuelan–French team.

The Orinoco Delta, and tributaries in the eastern llanos such as the Apure and Meta, were explored in the 16th century by German expeditions under Ambrosius Ehinger and his successors. In 1531 Diego de Ordaz, starting at the principal outlet in the delta, the Boca de Navios, sailed up the river to the Meta. Antonio de Berrio sailed down the Casanare to the Meta, and then down the Orinoco and back to Coro. In 1595 after capturing de Berrio for information the Englishmen Walter Raleigh in an expedition to find the fabled city of El Dorado sailed own the river reaching the savannah country.

Alexander von Humboldt explored the basin in 1800, reporting on the pink river dolphins. He published extensively on the river's flora and fauna.[2]

The first bridge across the Orinoco was the Angostura Bridge at Ciudad Bolívar, Venezuela, completed in 1967.[3] In 2006 a second bridge was completed near Ciudad Guayana, Venezuela, known as the Orinoquia Bridge.

The first powerline crossing of the Orinoco was completed in 1981 for an 800 kV TL single span of 1,200 meters using two towers 110 m tall.[4] In 1992, an overhead power line crossing for two 400 kV-circuits was completed just west of Morocure (between the cities of Ciudad Bolivar and Ciudad Guayana), north of the confluence of Routes 1 and 19. It had three towers, and the two spans measured 2,161 m and 2,537 m respectively.[4][5][6][7]

Geography

The course of the Orinoco forms a wide ellipsoidal arc, surrounding the Guiana Shield; it is divided in four stretches of unequal length that roughly correspond to the longitudinal zonation of a typical large river:

View of the Orinoco River in Mariusa National Park (Delta Amacuro)
Orinoco River at its confluence with the Caroní River (lower left)[8]
Rapids of the Orinoco River, near Puerto Ayacucho airport, Venezuela
The Orinoco River, here in Amazonas State, Venezuela
Orinoco River, in Amazonas State, Venezuela

At its mouth, the Orinoco forms a wide delta that branches off into hundreds of rivers and waterways that flow through 41,000 km2 (16,000 sq mi) of swampy forests. In the rainy season, the Orinoco can swell to a breadth of 22 kilometres (14 mi) and a depth of 100 metres (330 ft).

Most of the important Venezuelan rivers are tributaries of the Orinoco, the largest being the Caroní, which joins it at Puerto Ordaz, close to the Llovizna Falls. A peculiarity of the Orinoco river system is the Casiquiare canal, which starts as an arm of the Orinoco, and finds its way to the Rio Negro, a tributary of the Amazon, thus forming a 'natural canal' between Orinoco and Amazon.

Major rivers in the Orinoco Basin

Ecology

The boto (also called the "Amazon river dolphin") and the giant river otter inhabit the Orinoco River system.[9] The Orinoco crocodile is one of the rarest reptiles in the world. Its range in the wild is restricted to the Orinoco River Basin.

More than 1000 fish species have been recorded in the river basin.[9] Among these are species found in brackish or salt water in the Orinoco estuary, but also many restricted to fresh water. By far the largest orders are Characiformes and Siluriformes, which together account for more than half the fresh water species.[10] Some of the more famous are the black spot piranha and the cardinal tetra. The latter species, which is important in the aquarium industry, is also found in the Rio Negro, revealing the connection between this river and the Orinoco through the Casiquiare canal.[11]

Economic activity

The river is navigable for most of its length, and dredging enables ocean ships to go as far as Ciudad Bolívar, at the confluence of the Caroní River, 435 kilometres (270 mi) upstream. River steamers carry cargo as far as Puerto Ayacucho and the Atures Rapids.

El Florero iron mine

In 1926 a Venezuelan mining inspector found one of the richest iron ore deposits near the Orinoco delta, south of the town of San Felix on a mountain name El Florero. Full-scale mining of the ore deposits began after World War II, by a conglomerate of Venezuelan firms and US steel companies. At the start in the early 1950s, about 10,000 tons of ore-bearing soil was mined per day.[12]

Tar sands

The Orinoco river deposits also contain extensive tar sands in the Orinoco oil belt, which may be a source of future oil production.[13]

Eastern Venezuelan basin

Union of the Orinoco with the Caroní River.

Encompassing the states of Anzoategui-Guarico and Monagas states, the Interior Range forms the northern boundary and the Guayana Shield the southern.[14]:155 Maturin forms the eastern subbasin and Guarico the western.[14]:156 The El Furrial oil field was discovered in 1978, producing from late Oligocene shallow marine sandstones in an overthrusted foreland basin.[14]:155

Recreation and sports

Since 1988, the local government of Ciudad Guayana has conducted a swim race in the rivers Orinoco and Caroní, with up to 1000 competitors. Since 1991, the "Paso a Nado Internacional de los Rios Orinoco-Caroní" has been celebrated every year, on a Sunday close to 19 April. Worldwide, this swim-meet has gained in importance, and it has a large number of competitors.[15]

Notes

  1. ↑ Orinoco River at GEOnet Names Server
  2. ↑ Helferich, Gerard (2004) Humboldt's Cosmos: Alexander von Humboldt and the Latin American Journey that Changed the Way We See the World, Gotham Books, New York, ISBN 1-59240-052-3.
  3. ↑ Scott, R. (2001). In the Wake of Tacoma: Suspension Bridges and the Quest for Aerodynamic Stability. American Society of Civil Engineers. p. 184. ISBN 9780784470732. Retrieved 2015-04-13.
  4. 1 2 "Experience". SAE Power Lines.
  5. ↑ "Critical Path" (PDF). PEI (magazine). June 2005. pp. 105–111, page 107. Archived from the original (PDF) on 23 September 2006.
  6. ↑ "Pylons of the Orinoco High-Voltage Crossing". International Database for Civil and Structural Engineering. Archived from the original on 13 October 2015.
  7. ↑ "Orinoco Powerline Crossing". Skyscraper Source Media Inc. Archived from the original on 13 October 2015.
  8. ↑ "Ciudad Guayana, Venezuela : Image of the Day". earthobservatory.nasa.gov. Retrieved 2009-10-31.
  9. 1 2 WWF: Orinoco River Basin, South America. Retrieved 24 May 2014
  10. ↑ Hales, J., and P. Petry: Essequibo. Orinoco Delta & Coastal Drainages. Retrieved 24 May 2014.
  11. ↑ Seriously Fish: Paracheirodon axelrodi, Cardinal Tetra. Retrieved 24 May 2014
  12. ↑ "Venezuela's Magnetic Mountain" Popular Mechanics, July 1949
  13. ↑ Forero, Juan (1 June 2006) "For Venezuela, A Treasure In Oil Sludge" New York Times Vol. 155 Issue 53597, pC1-C6
  14. 1 2 3 Prieto, R., Valdes, G., 1992, El Furrial Oil Field, In Giant Oil and Gas Fields of the Decade, 1978-1988, AAPG Memoir 54, Halbouty, M.T., editor, Tulsa: American Association of Petroleum Geologists, ISBN 0891813330
  15. ↑ "Antecedentes y Sumario Paso a Nado Internacional de Los Rios Orinoco/Caroni" Paso Nado Internacional de Los Rios Orinoco y Caroní Official website in Spanish, translation of title: "Antecedents and Summary of the International Swim Meet of the Orinoco and Caroni Rivers"

See also

References

External links

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