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For other uses, see Orinoco (disambiguation).

The Orinoco (Spanish pronunciation: [oɾiˈnoko]) is one of the longest rivers in South America at 2,250 kilometres (1,400 mi).[citation needed]

Its drainage basin, sometimes known as the Orinoquia,[3] covers 989,000 km2 (382,000 sq mi), with 76% of it in Venezuela and the remainder in Colombia. It is the fourth largest river in the world by discharge volume of water. The Orinoco River and its tributaries are the major transportation system for eastern and interior Venezuela and the Llanos of Colombia. The environment and wildlife in the Orinoco's basin are extremely diverse.

Etymology

The river's name is derived from the Warao term for "a place to paddle", itself derived from the terms güiri (paddle) and noko (place) i.e. a navigable place.[4][5]

History

Map of the Lower Orinoco, 1897

The mouth of the Orinoco River at the Atlantic Ocean was documented by Christopher Columbus on 1 August 1498, during his third voyage. Its source at the Cerro Delgado–Chalbaud, in the Parima range, was not explored until 453 years later, in 1951. The source, near the Venezuelan–Brazilian border, at 1,047 metres (3,435 ft) above sea level (2°19′05″N 63°21′42″W / 2.31806°N 63.36167°W / 2.31806; -63.36167), was explored in 1951 by a joint French-Venezuelan expedition.

The Orinoco, as well as its 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, starting at the principal outlet in the delta, the Boca de Navios, Diego de Ordaz sailed up the river to the Meta. Antonio de Berrio sailed down the Casanare to the Meta, and then down the Orinoco River and back to Coro. In 1595, after capturing de Berrio to obtain information while conducting an expedition to find the fabled city of El Dorado, the Englishman Sir Walter Raleigh sailed down the river, reaching the savanna 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.[6]

The sources of the Orinoco River, located at Cerro Carlos Delgado Chalbaud (2º19’05” N, 63º21’42” W), were discovered in 1951 by the French-Venezuelan expedition that went back and explored the Upper Orinoco course to the Sierra Parima near the border with Brazil, headed by Venezuelan army officer Frank Risquez Iribarren.[7][8]

The first bridge across the Orinoco River, the Angostura Bridge at Ciudad Bolívar, Venezuela, was completed in 1967.[9]

In 1968, an expedition was set off by National Geographic and Hovercraft from Manaus (Brazil) to Port of Spain (Trinidad). Aboard a SR.N6 hovercraft, the expedition members followed the Negro river upstream to where it is joined by the Casiquiare canal, on the border between Colombia and Venezuela. After following the Casiquiare to the Orinoco River they hovered thru perilous rapids of the rivers Maipures and Atures. The Orinoco was then traversed down to its mouths in the Gulf of Paria and then to Port of Spain. The primary purpose of the expedition was filming for the BBC series The World About Us episode "The Last Great Journey on Earth from Amazon to Orinoco by Hovercraft", which aired in 1970, and demonstrated the abilities of a hovercraft, thereby promoting sales of this British invention.

The first powerline crossing of the Orinoco River was completed in 1981 for an 800 kV TL single span of 1,200 metres (3,900 ft) using two towers 110 metres (360 ft) tall.[10]

In 1992, an overhead power line crossing for two 400 kV-circuits was completed just west of Morocure (between the cities of Ciudad Bolívar and Ciudad Guayana), north of the confluence of Routes 1 and 19. It had three towers, and the two spans measured 2,161 metres (7,090 ft) and 2,537 metres (8,323 ft), respectively.[10][11][12][13]

In 2006, a second bridge, known as the Orinoquia Bridge, was completed near Ciudad Guayana, Venezuela.[citation needed]

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 very roughly correspond to the longitudinal zonation of a typical large river:

  • Upper Orinoco – 286 kilometres (178 mi) long, from its headwaters to the Raudales de Guaharibos rapids, flows through mountainous landscape in a northwesterly direction
  • Middle Orinoco – 805 kilometres (500 mi) long, divided into two sectors, the first of which ca. 515 kilometres (320 mi) long has a general westward direction down to the confluence with the Atabapo and Guaviare rivers at San Fernando de Atabapo; the second flows northward, for about 290 kilometres (180 mi), along the Venezuelan–Colombian border, flanked on both sides by the westernmost granitic upwellings of the Guiana Shield which impede the development of a flood plain, to the Atures rapids near the confluence with the Meta River at Puerto Carreño
  • Lower Orinoco – 959 kilometres (596 mi) long with a well-developed alluvial plain, flows in a northeast direction, from Atures rapids down to Piacoa in front of Barrancas
  • Delta Amacuro – 200 kilometres (120 mi) long that empties into the Gulf of Paría and the Atlantic Ocean, a very large delta, some 22,500 km2 (8,700 sq mi) and 370 kilometres (230 mi) at its widest.
Orinoco in Mariusa National Park (Delta Amacuro)
Orinoco at its confluence with the Caroní River (lower left)[14]
Rapids of the Orinoco, near Puerto Ayacucho airport, Venezuela
Orinoco in Amazonas State, Venezuela
Orinoco in Amazonas State, Venezuela

At its mouth, the Orinoco River 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 River 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 River, 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.

The stream gradient of the entire river is 0.05% (1,047 m over 2,250 km). Downstream of Raudales de Guaharibos the gradient is 0.01% (183[15]/1,964), which is also the gradient from Ciudad Bolivar to the ocean (54/435).

Major rivers in the Orinoco Basin

  • Apure: from Venezuela through the east into the Orinoco
  • Arauca: from Colombia to Venezuela east into the Orinoco
  • Atabapo: from the Guiana Highlands of Venezuela north into the Orinoco
  • Caroní: from the Guiana Highlands of Venezuela north into the Orinoco
  • Casiquiare canal: in SE Venezuela, a distributary from the Orinoco flowing west to the Negro River, a major affluent to the Amazon
  • Caura: from eastern Venezuela (Guiana Highlands) north into the Orinoco
  • Guaviare: from Colombia east into the Orinoco
  • Inírida: from Colombia southeast into the Guaviare.
  • Meta: from Colombia, border with Venezuela east into the Orinoco
  • Ventuari: from eastern Venezuela (the Guiana Highlands) southwest into the Orinoco
  • Vichada: from Colombia east into the Orinoco
See also: Casiquiare canal-Orinoco River hydrographic divide

Discharge

Average, minimum and maximum discharge at Ciudad Bolívar and Ciudad Guayana (Lower Orinoco):

Year Discharge (m3/s)
Ciudad Bolívar Ciudad Guayana
Min Mean Max Min Mean Max
2000 4,799 33,415 67,667 71,080
2001 3,438 25,695 59,527 60,493
2002 3,868 34,002 74,367 66,561
2003 3,287 34,728 74,367 77,802
2004 4,071 35,717 74,208 66,367
2005 5,439 31,980 64,800 57,471
2006 6,521 35,901 77,422 71,446
2007 3,949 34,477 71,527 65,611
2008 4,754 32,378 70,536
2009 7,419 26,041 59,671 67,992
2010 3,067 35,286 75,807 40,101 86,581
2011 6,368 37,957 74,367 40,189 92,258
2012 7,805 38,685 77,909 44,049 74,566
2013 5,581 32,041 65,850 36,484 62,151
2014 4,364 31,632 71,214 36,018 66,050
2015 5,725 29,476 71,136 33,742 65,903
2016 3,514 35,474 78,398 39,841 83,098
2017 7,520 34,302 77,315 8,936 39,057 85,997
2018 4,693 36,467 82,611 6,637 40,870 87,303
2019 4,846 32,017 72,203 34,620 70,248
2020 4,570 28,915 63,638 6,018 31,551 54,640
2021 7,279 39,378 74,873 9,199 42,786 79,487
2022 6,463 39,094 75,912 9,679 42,663 85,238
2023 8,377 32,523 68,742 8,774 36,380 81,831

[16][17]

Monthly average discharge (m3/s) at Ciudad Bolívar (2018 to 2023):

Month 2018 2019 2020 2021 2022 2023 1926–2023
JAN 11,009 8,955 13,667 19,108 11,067 14,528 11,637
FEB 7,593 6,414 7,142 9,554 6,463 9,412 6,840
MAR 4,693 4,846 4,570 7,279 10,187 8,377 5,521
APR 6,862 5,634 5,080 16,378 13,860 10,036 7,347
MAY 27,262 17,343 11,688 33,363 28,156 19,290 20,295
JUN 46,541 36,447 29,204 63,086 50,344 41,963 39,205
JUL 73,295 57,240 42,542 68,208 68,499 59,398 57,550
AUG 82,611 72,203 57,742 74,873 75,912 68,742 69,207
SEP 70,591 69,859 63,638 68,441 73,589 67,129 66,502
OCT 50,838 48,298 50,060 53,294 54,020 52,622 51,206
NOV 34,852 34,644 36,926 36,518 45,509 23,332 35,752
DEC 21,457 22,317 24,718 22,437 31,527 15,450 22,974
Mean 36,467 32,017 28,915 39,378 39,094 32,523 32,836

[16]

Monthly average discharge (m3/s) at Ciudad Guayana (1996 to 1998):

Month 1996 1997 1998 1943–1998
JAN 17,627 24,386 10,919 16,661
FEB 14,486 17,144 7,583 10,108
MAR 15,334 15,767 8,906 7,702
APR 12,514 12,615 12,411 10,609
MAY 23,670 25,152 32,751 26,317
JUN 45,781 43,142 49,062 45,179
JUL 61,177 55,597 63,659 58,412
AUG 67,639 61,275 67,756 64,975
SEP 65,933 53,825 66,416 63,244
OCT 57,912 38,742 54,189 53,201
NOV 45,267 28,372 38,345 40,805
DEC 36,094 21,116 30,130 29,229
Mean 38,620 33,094 36,844 35,537

[18]

Average discharge at Ciudad Bolívar (complete time series from 1926 to 2023):

Year m3/s Year m3/s Year m3/s
1926 23,376 1959 30,333 1992 28,571
1927 37,476 1960 31,818 1993 35,204
1928 32,838 1961 27,830 1994 35,110
1929 32,653 1962 32,930 1995 29,360
1930 30,610 1963 32,560 1996 35,992
1931 33,766 1964 27,736 1997 28,757
1932 33,302 1965 27,643 1998 35,000
1933 32,792 1966 29,220 1999 34,925
1934 34,137 1967 34,323 2000 33,415
1935 31,168 1968 32,280 2001 25,695
1936 31,260 1969 32,606 2002 34,002
1937 29,962 1970 34,600 2003 34,728
1938 37,383 1971 33,673 2004 35,717
1939 28,292 1972 36,177 2005 31,980
1940 25,232 1973 27,597 2006 35,901
1941 28,200 1974 26,344 2007 34,477
1942 31,540 1975 29,313 2008 32,378
1943 38,403 1976 37,290 2009 26,041
1944 34,878 1977 30,705 2010 35,286
1945 33,395 1978 32,514 2011 37,957
1946 36,363 1979 32,885 2012 38,685
1947 30,426 1980 35,018 2013 32,041
1948 31,818 1981 38,080 2014 31,632
1949 32,745 1982 36,224 2015 29,476
1950 32,096 1983 36,130 2016 35,474
1951 38,220 1984 31,493 2017 34,302
1952 33,858 1985 30,380 2018 36,467
1953 36,177 1986 35,040 2019 32,017
1954 38,310 1987 34,090 2020 28,915
1955 31,076 1988 30,472 2021 39,378
1956 36,734 1989 29,638 2022 39,094
1957 29,128 1990 33,442 2023 32,523
1958 28,108 1991 31,770 2024

[19][20][21]

Ecology

The boto and the giant otter inhabit the Orinoco River system.[22] The Orinoco crocodile is one of the rarest reptiles in the world. Its range in the wild is restricted to the middle and lower Orinoco River Basin.[23]

More than 1000 fish species have been recorded in the river basin and about 15% are endemic.[24] Among the fish in the river 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 80% of the fresh water species.[25] 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.[26] Because the Casiquiare includes both blackwater and clear- to whitewater sections, only relatively adaptable species are able to pass through it between the two river systems.[27]

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 city of San Felix on a mountain named 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.[28]

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.[29]

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 boundary.[30]: 155  Maturin forms the eastern subbasin and Guarico forms the western subbasin.[30]: 156  The El Furrial oil field was discovered in 1978, producing from late Oligocene shallow marine sandstones in an overthrusted foreland basin.[30]: 155 

Recreation and sports

Since 1973, the Civil Association Nuestros Rios son Navegables organize the Internacional Rally Nuestros Rios son Navegables, a motonautical round trip of over 1,200 kilometers through the Orinoco, Meta and Apure Rivers. Starting out from Ciudad Bolívar or San Fernando de Apure, is the longest fluvial rally in the world with the participation of worldwide competitors, more than 30 support boats, logistics teams, thousands of tourists and fans travel. The boats had an average speed of 120 miles per hour.

Since 1988, the local government of Ciudad Guayana has conducted a swim race in the rivers Orinoco and Caroní, with up to 1,000 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 grown in importance, and it has a large number of competitors.[31] The 26th meet was held in 2016.[32]

In culture

The Irish singer and songwriter Enya wrote and sang the song "Orinoco Flow", which she released in 1988.[33] Jule Verne's novel Superbe Orénoque has the river as its central theme.

See also

Notes

  1. ^ Orinoco River at GEOnet Names Server
  2. ^ a b c José Rafael, Córdova; Marcelo González, Sanabria. "La geografía del agua" (PDF).
  3. ^ "Orinoquia, Orinoquía". Diccionario panhispánico de dudas. Royal Spanish Academy. 2005. Retrieved 2023-01-07.
  4. ^ "Orinoco River". Encyclopaedia Britannica. Retrieved 11 April 2020.
  5. ^ "Orinoco". Diccionario Etimológico Español en Línea. Retrieved 11 April 2020.
  6. ^ 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.
  7. ^ Alberto Contramaestre Torres. Expedición a las fuentes del Orinoco. Caracas, 1954.
  8. ^ Pablo J. Anduce. Shailili-Ko. Descubrimiento de las fuentes del Orinoco. Caracas: Talleres Gráficos Ilustraciones S.A., 1960.
  9. ^ 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 13 April 2015.
  10. ^ a b "Experience". SAE Power Lines. Archived from the original on 2 August 2015. Retrieved 13 October 2015.
  11. ^ "Critical Path" (PDF). PEI. June 2005. pp. 105–111, page 107. Archived from the original (PDF) on 23 September 2006.
  12. ^ "Pylons of the Orinoco High-Voltage Crossing". International Database for Civil and Structural Engineering. Archived from the original on 4 March 2016. Retrieved 13 October 2015.
  13. ^ "Orinoco Powerline Crossing". Skyscraper Source Media Inc. Archived from the original on 5 March 2016.
  14. ^ "Ciudad Guayana, Venezuela : Image of the Day". earthobservatory.nasa.gov. 2006-01-23. Retrieved 2009-10-31.
  15. ^ "Raudal de Guaharibos rapids, Estado Amazonas, Venezuela". ve.geoview.info. Retrieved 2021-07-21.
  16. ^ a b "Actualidad Hidrometeorológica".
  17. ^ "The Flood Observatory".
  18. ^ NATURAL CONDITIONS OF THE ORINOCO RIVER DELTA (PDF).
  19. ^ José L., López; José R., Córdova; Bartolo, Castellanos; Santiago, Yépez; Alain, Laraque. "THE EXTRAORDINARY FLOOD OF THE ORINOCO RIVER IN 2018" (PDF).
  20. ^ "Actualidad Hidrometeorológica".
  21. ^ "The Flood Observatory".
  22. ^ WWF: Orinoco River Basin, South America. Retrieved 24 May 2014
  23. ^ Thorbjarnarson, John B.; Hernández, Gustavo (1993). "Reproductive ecology of the Orinoco crocodile (Crocodylus intermedius) in Venezuela. I. Nesting ecology and egg and clutch relationships". Journal of Herpetology. 27 (4): 363–370. doi:10.2307/1564821. JSTOR 1564821.
  24. ^ Reis, R. E.; Albert, J. S.; Di Dario, F.; Mincarone, M. M.; Petry, P.; Rocha, L. A. (2016). "Fish biodiversity and conservation in South America". Journal of Fish Biology. 89 (1): 12–47. doi:10.1111/jfb.13016. PMID 27312713.
  25. ^ Hales, J., and P. Petry: Orinoco Llanos. Orinoco Delta & Coastal Drainages. Retrieved 24 May 2014.
  26. ^ "Paracheirodon axelrodi, Cardinal Tetra". Seriously Fish. Retrieved 24 May 2014.
  27. ^ Staeck, W.; Schindler, I. (2015). "Description of a new Heros species (Teleostei, Cichlidae) from the Rio Orinoco drainage and notes on Heros severus Heckel, 1840" (PDF). Bulletin of Fish Biology. 15 (1–2): 121–136. Archived (PDF) from the original on 2022-10-09.[permanent dead link]
  28. ^ "Venezuela's Magnetic Mountain" Popular Mechanics, July 1949
  29. ^ Forero, Juan (1 June 2006). "For Venezuela, A Treasure In Oil Sludge". The New York Times. Vol. 155, no. 53597. pp. C1–C6. Archived from the original on 20 December 2016.
  30. ^ a b c 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
  31. ^ "Antecedentes y Sumario Paso a Nado Internacional de Los Rios Orinoco/Caroni" Paso Nado Internacional de Los Rios Orinoco y Caroní" [Antecedents and Summary of the International Swim Meet of the Orinoco and Caroni Rivers] (in Spanish). Archived from the original on 17 December 2007.
  32. ^ "26 edición Paso a Nado de Ríos Orinoco y Caroní 2016". Roberto Muñoz Natación Venezuela. Archived from the original on 9 November 2016.
  33. ^ Moore, Rick (2020-11-18). "Behind the Song: "Orinoco Flow (Sail Away)" by Enya". American Songwriter. Retrieved 2023-12-27.

References

  • Stark, James H. 1897. Stark's Guide-Book and History of Trinidad including Tobago, Granada, and St. Vincent; also a trip up the Orinoco and a description of the great Venezuelan Pitch Lake. Boston, James H. Stark, publisher; London, Sampson Low, Marston & Company. (This book has an excellent description of a trip up the Orinoco as far as Ciudad Bolívar and a detailed description of the Venezuelan Pitch Lake situated on the western side of the Gulf of Paria opposite.)
  • MacKee, E.D., Nordin, C.F. and D. Perez-Hernandez (1998). "The Waters and Sediments of the Rio Orinoco and its major Tributaries, Venezuela and Colombia." United States Geological Survey water-supply paper, ISSN 0886-9308 /A-B. Washington: United States Government Printing Office.
  • Rawlins, C.B. (1999). The Orinoco River. New York: Franklin Watts.
  • Triana, S. Pérez. Down the Orinoco in a Canoe
  • Weibezahn, F.H., Haymara, A. and M.W. Lewis (1990). The Orinoco River as an ecosystem. Caracas: Universidad Simon Bolivar.

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