Rio Negro (Amazon)

For other uses, see Rio Negro (disambiguation).

The Rio Negro (Spanish: Río Negro [ˈri.o ˈneɣɾo] "Black River"), or Guainía as it is known in its upper part, is the largest left tributary of the Amazon River (accounting for about 14% of the water in the Amazon basin), the largest blackwater river in the world,^[8] and one of the world's ten largest rivers by average discharge. Despite its high flow, the Rio Negro has a low sediment load (5.76 million tonnes per year on average in Manaus).^[4]

Rio Negro Guainía River
Sunset over the Rio Negro, upstream from Manaus
Map showing the Rio Negro in the Amazon Basin
Native name	Rio Negro (Portuguese) Río Negro (Spanish)
Location
Countries	Colombia Venezuela Brazil
Physical characteristics
Source	highlands of Colombia
• location	Guainía Department, Amazon region, Colombia
• coordinates	1°56′50″N 70°1′55″W (approximately)
• elevation	250 m (820 ft) (approximately)
Mouth	Amazon River
• location	Manaus, Amazonas State, Brazil
• coordinates	3°08′00″S 59°54′30″W
• elevation	8 m (26 ft)[1]
Length	Rio Negro–Guainía 2,250 km (1,400 mi)[2]
Basin size	714,577.6 km2 (275,900.0 sq mi)[3]
Width
• average	2,450 m (8,040 ft)[4]
Depth
• average	20 m (66 ft) (Serrinha); 24 m (79 ft) to 31 m (102 ft) (Manaus)[3]
• maximum	60 m (200 ft) (Manaus)[4]
Discharge
• location	Manaus
• average	(Period: 2015–2019)34,573 m3/s (1,220,900 cu ft/s)[4]
• minimum	4,240 m3/s (150,000 cu ft/s)[3]
• maximum	64,380 m3/s (2,274,000 cu ft/s)[3]
Discharge
• location	Paricatuba (Anavilhanas)
• average	(Period: 2008–2019)34,444 m3/s (1,216,400 cu ft/s)[5]
• minimum	7,633 m3/s (269,600 cu ft/s) (2009/10)[5]
• maximum	65,510 m3/s (2,313,000 cu ft/s) (2014/06)[5]
Discharge
• location	Serrinha, 0°28′57.4716″S 64°49′36.6492″W
• average	(Period: 1997–2015)16,845.5 m3/s (594,890 cu ft/s)[6]
• minimum	5,000 m3/s (180,000 cu ft/s)[7]
• maximum	30,000 m3/s (1,100,000 cu ft/s)[7]
Discharge
• location	São Felipe, 0°22′11.8056″N 67°18′42.9948″W
• average	(Period: 1997–2014)8,314.5 m3/s (293,620 cu ft/s)[6]
• minimum	1,200 m3/s (42,000 cu ft/s)[7]
• maximum	15,500 m3/s (550,000 cu ft/s)[7]
Discharge
• location	Cucuí
• average	(Period: 1997–2014)5,113.1 m3/s (180,570 cu ft/s)[6]
• minimum	400 m3/s (14,000 cu ft/s)[7]
• maximum	10,500 m3/s (370,000 cu ft/s)[7]
Basin features
Progression	Amazon → Atlantic Ocean
River system	Amazon River
Tributaries
• left	Casiquiare, Cauaburi, Marauiá, Macucuaú, Padauari, Demini, Jufari, Branco, Jauaperi, Camanaú, Baependi, Apuaú, Cuieiras, Tarumã Mirim, Tarumã Açu
• right	Guainía (Upper Negro), Xié, Içana, Uaupés, Curicuriari, Marié, Tea, Uneiuxi, Aiuanã, Urubaxi, Ararirá, Cuiuni, Caurés, Unini, Jaú, Puduari

Geography

Rio Negro watershed (Interactive map)

Upper course

The source of the Rio Negro lies in Colombia, in the Department of Guainía where the river is known as the Guainía River.^[9] The young river generally flows in an east-northeasterly direction through the Puinawai National Reserve, passing several small indigenous settlements on its way, such as Cuarinuma, Brujas, Santa Rosa and Tabaquén. After roughly 400 km (250 mi) the river starts forming the border between Colombia's Department of Guainía and Venezuela's Amazonas State. After passing the Colombian community of Tonina and Macanal the river turns southwest. Maroa is the first Venezuelan town the river passes. 120 km (75 mi) further downstream the river receives the Casiquiare canal from the left (north), forming a unique link between the Orinoco and the Amazon river basin. Henceforth the river is called Rio Negro.

Middle course

The river now continues in a southeastern direction passing the Venezuelan town of San Carlos de Río Negro, its largest settlement on the river, and Colombia's San Felipe. In this stretch the river is constantly fed with tributaries from both sides, and it quickly grows in size creating large river islands, a common feature for all rivers in the Amazon basin. After forming the border between Colombia and Venezuela for 260 km (160 mi) the Rio Negro reaches the Piedra del Cocuy, an igneous rock formation from the Precambrian era, belonging to the Guyana Shield. Here the Tripoint of Colombia, Venezuela and Brazil is found in the middle of the river and it now completely enters Amazonas State, Brazil. After passing Cucuí, the river continues south, only temporarily turning west for several kilometers. In Missão Boa Vista the Içana River joins the Rio Negro and in São Joaquim the Uaupes River, the largest tributary of the Rio Negro, also enters from the right hand side. The Rio Negro now turns markedly towards the east, forming several rapids and small islets on its way. It then passes Sao Gabriel da Cachoeira an important commercial city. After several more rapids and imposing views of the Adormecida mountain chain the river leaves the Guyana shield it traversed in its upper and middle course.

Lower course

The confluence of the Amazon River and the Rio Negro at Manaus, Brazil.

After the Marié River enters the Rio Negro the river continues its eastward course forming many large islands and becoming very wide at several locations. It passes local communities such as Santa Isabel do Rio Negro. During the wet season, the river floods the country far and wide here, sometimes to a width of 30 km (19 mi), for long distances. During this season, from April until October, it is a succession of lagoons, full of long islands and intricate channels with a lot of water wildlife. Near Carvoeiro the last major tributary of the Rio Negro, the Branco River joins the Rio Negro and the river temporarily forms the border between the state of Roraima and Amazonas State, Brazil. The river now takes a more southeastern course, becoming again very wide in many stretches before reaching the biggest city on its course Manaus.

The Anavilhanas National Park, a 350,018 ha (864,910 acres) conservation unit that was originally an ecological station created in 1981, protects part of the Anavilhanas river archipelago in this part of the river.^[10] Below the archipelago, it meets the Solimões River to form the Amazon River, creating a phenomenon known as the Meeting of Waters.

Major tributaries

List of the major tributaries of the Rio Negro (from the mouth upwards)^{[11][3][12][13]}

Left tributary	Right tributary	Length		Basin size		Average discharge
		km	mi	km2	sq mi	m3/s	cu ft/s
Rio Negro		2,362	1,468	719,216	277,691	30,640.8	1,082,070
Lower Rio Negro
Taruma-Açu		139	86	1,372	530	52.3	1,850
Cuieiras				3,441	1,329	144.2	5,090
Apuaú				3,799.1	1,466.8	153.6	5,420
	Puduari			3,411.5	1,317.2	128.6	4,540
Camanaú				11,832.2	4,568.4	408	14,400
	Jaú	400	250	18,896.6	7,296.0	869.2	30,700
Jauaperi		554	344	39,823.5	15,375.9	1,336.8	47,210
	Unini	530	330	27,433	10,592	1,501.4	53,020
Branco		1,430	890	190,789.2	73,664.1	5,400	190,000
Jufari		311	193	12,590.5	4,861.2	446.6	15,770
	Cauarés			7,332.3	2,831.0	296	10,500
Demini				39,769.6	15,355.1	1,357.9	47,950
	Cuiuni	400	250	11,776.1	4,546.8	491.6	17,360
Igarapé Adairá				3,294.9	1,272.2	101.1	3,570
	Ararirá			3,425	1,322	114.6	4,050
Ererê				3,251	1,255	115.7	4,090
Padauari				17,384	6,712	606.8	21,430
Daraá				3,053.3	1,178.9	114.9	4,060
	Urubaxi	250	160	6,855.9	2,647.1	311.6	11,000
	Aiuanã			4,590.7	1,772.5	185.2	6,540
	Uneiuxi			12,474.7	4,816.5	488.3	17,240
	Teá			6,365.9	2,457.9	201.4	7,110
Marauiá				6,712	2,592	255.3	9,020
Igarapé Inambu				4,618.8	1,783.3	140.6	4,970
Cauaburi				12,139.3	4,687.0	442.9	15,640
Middle Rio Negro
	Marié	800	500	25,378	9,799	1,226.8	43,320
	Curicuriari			14,202.2	5,483.5	916.8	32,380
	Uaupés	1,375	854	64,370.4	24,853.6	4,344.9	153,440
	Içana	696	432	35,675.3	13,774.3	2,278.9	80,480
	Xié			8,222	3,175	488.1	17,240
Upper Rio Negro
Casiquiare		354	220	42,478	16,401	2,575.8	90,960
	Guainía	617	383	28,899.5	11,158.2	2,432.7	85,910

Discharge

Rio Negro at Manaus (1970–2023):^[14]

Year	Average discharge (m3/s)
2023	20,000
2022	33,000
2021	35,000
2020	30,000
2019	32,600
2018	29,300
2017	31,200
2016	25,000
2015	34,000
2014	40,000
2013	32,600
2012	29,700
2011	23,200
2010	20,500
2009	32,000
2008	33,000
2007	29,500
2006	25,500
2005	28,200
2004	33,000
2003	31,600
2002	29,400
2001	31,000
2000	31,700
1999	28,000
1998	20,500
1997	29,000
1996	30,000
1995	27,400
1994	38,000

(continues)

Year	Average discharge (m3/s)
1993	33,700
1992	23,000
1991	25,500
1990	29,500
1989	34,500
1988	30,800
1987	44,000
1986	40,300
1985	34,000
1984	32,400
1983	27,800
1982	32,000
1981	27,700
1980	26,500
1979	34,200
1978	38,700
1977	36,000
1976	36,300
1975	42,000
1974	50,800
1973	40,400
1972	40,800
1971	39,000
1970	30,000
1926	17,500

Average discharge

Period	Discharge	Ref.
Encontro das Águas
1979–2015	30,640.8 m3/s (1,082,070 cu ft/s)	[11]
1971–2000	29,615.7 m3/s (1,045,870 cu ft/s)	[12]
Manaus 3°8′19.3704″S 60°1′39.522″W
2015–2019	34,573 m3/s (1,220,900 cu ft/s)	[4]
1980–2006	35,943 m3/s (1,269,300 cu ft/s)	[15]
1973–1992	28,400 m3/s (1,000,000 cu ft/s)	[16]
1971–2000	29,607.4 m3/s (1,045,580 cu ft/s)	[12]
Paricatuba 3°4′53.2848″S 60°14′0.4812″W
2008–2019	34,444 m3/s (1,216,400 cu ft/s)	[5]
1971–2000	29,518.2 m3/s (1,042,430 cu ft/s)	[12]
Barcelos 0°58′59.6964″S 62°51′32.3892″W
1971–2000	19,545.2 m3/s (690,230 cu ft/s)	[12]
Serrinha 0°28′57.4716″S 64°49′36.6492″W
1997–2015	16,845.5 m3/s (594,890 cu ft/s)	[6]
1980–2006	18,082 m3/s (638,600 cu ft/s)	[15]
1971–2000	16,611.9 m3/s (586,640 cu ft/s)	[12]
São Gabriel da Cachoeira 0°8′2.9616″S 67°5′38.2956″W
1971–2000	13,150.7 m3/s (464,410 cu ft/s)	[12]
São Felipe 0°22′11.8056″N 67°18′42.9948″W
1997–2014	8,314.5 m3/s (293,620 cu ft/s)	[6]
1980–2006	7,984 m3/s (282,000 cu ft/s)	[15]
1971–2000	8,244.8 m3/s (291,160 cu ft/s)	[12]
Cucuí 1°11′16.7316″S 66°50′23.46″W
1997–2014	5,113.1 m3/s (180,570 cu ft/s)	[6]
1980–2006	4,940 m3/s (174,000 cu ft/s)	[15]
1971–2000	5,065.1 m3/s (178,870 cu ft/s)	[12]

History

The river was named by the Spanish explorer Francisco de Orellana, who first came upon it in 1541. By the middle of the 17th century, Jesuits had settled along its banks in the midst of numerous tribes: Manau, Aruák, and Trumá Indians. After 1700 slaving along the river was common, and Native American populations were greatly diminished after contact with Eurasian diseases.^[9] In 1800 German scientist Alexander von Humboldt^[17] and French botanist Aimé Bonpland explored the river.^[18] During 1852-1854 Richard Spruce and Alfred Russel Wallace made numerous observations and botanical collections.^[19]During a 1924–25 expedition, Alexander H. Rice Jr. of Harvard University traveled up the Orinoco, traversed the Casiquiare canal, and descended the Rio Negro to the Amazon at Manaus. It was the first expedition to use aerial photography and shortwave radio for mapping of the region. In 1968 the Rio Negro was navigated by an SRN6 hovercraft during a National Geographic expedition.^[20]This area was the filming location for Survivor:The Amazon in 2003.

Fauna and flora

Rio Negro near Manaus

Victoria amazonica

While the name Rio Negro means Black River, its waters are similar in colour to strong tea, which is typical of blackwater rivers. The dark color comes from humic acid due to an incomplete breakdown of phenol-containing vegetation from sandy clearings. The river was named because it looks black from a distance.

Much has been written on the productivity of the Rio Negro and other blackwater rivers. The older idea that these are "hunger rivers" is giving way, with new research, to the recognition that the Rio Negro, for example, supports a large fishing industry and has numerous turtle beaches. If explorers did not find many Indigenous peoples along the Rio Negro during the 17th century, it is likely that their populations were reduced because of new infectious diseases and warfare rather than low river productivity.

Rio Negro has a very high species richness. About 700 fish species have been documented in the river basin, and it is estimated that the total is 800–900 fish species, including almost 100 endemics and several undescribed species.^[21] Among these are many that are important in the aquarium trade, including the cardinal tetra.^[21] As a result of the Casiquiare canal, many aquatic species are found both in the Rio Negro and Orinoco. 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.^[22]

In media

The sixth season of Survivor, Survivor: The Amazon was filmed in Rio Negro in 2003.

Notes

1. Tannenbaum, Frank (29 August 2012). TEN KEYS LAT AMER. Knopf Doubleday Publishing Group. ISBN 9780307826565. Retrieved 9 April 2018 – via Google Books.
2. Ziesler, R.; Ardizzone, G.D. (1979). "Amazon River System". The Inland waters of Latin America. Food and Agriculture Organization of the United Nations. ISBN 92-5-000780-9. Archived from the original on 8 November 2014.
3. "Amazon basin water resources observation service".
4. Rogério Ribeiro, Marinho; Naziano Filizola, Junior; Jean Michel, Martinez; Tristan, Harmel (2022). "Suspended sediment transport estimation in Negro River (Amazon Basin) using MSI/Sentinel-2 data". Revista Brasileira de Geomorfologia. 23. doi:10.20502/rbg.v23i1.2076.
5. Rogério Ribeiro, Marinho; Paulo Rodrigo, Zanin; Naziano Pantoja, Filizola Junior (2021). "The Negro River in the Anavilhanas Archipelago: Streamflow and geomorphology of a complex anabranching system in the Amazon". Earth Surface Processes and Landforms. 47 (4): 1108–1123. doi:10.1002/esp.5306.
6. Jamie, Towner (2019). "Assessing the performance of global hydrological models for capturing peak river flows in the Amazon basin" (PDF).
7. Juan Gabriel, Leon; Stèphane, Calmont; F., Seyler; Marie-Paule, Bonnet; Mathilde, Cauhopé; Frédéric, Frappart; Naziano, Filizola; Pascal, Fraizy (2010). "Rating curves and estimation of average water depth at the upper Negro River based on satellite altimeter data and modeled discharges". Journal of Hydrology. 328 (3–4): 481–496. doi:10.1016/J.JHYDROL.2005.12.006.
8. "Waters". Amazon Waters. 28 May 2014. Retrieved 10 October 2017.
9. Penn, James R (2001). Rivers of the World: A Social, Geographical and Environmental Sourcebook. Santa Barbara: ABC Clio.
10. PARNA de Anavilhanas (in Portuguese), ISA: Instituto Socioambiental, retrieved 2016-04-30
11. "PLANO ESTADUAL DE RECURSOS HÍDRICOS DO AMAZONAS, (PERH/AM) - RT 03 - DIAGNÓSTICO, PROGNÓSTICO E CENÁRIOS FUTUROS DO RECURSOS HÍDRICOS DO ESTADO - TOMO III" (PDF). Jan 2019. Archived from the original (PDF) on 2021-05-06. Retrieved 2021-10-03.
12. "Amazon".
13. Emilio, Mayorga; Miles, G. Logsdon; Maria Victoria, R. Ballester; Jeffrey, E. Richey (2005). "Estimating cell-to-cell land surface drainage paths from digital channel networks, with an application to the Amazon basin". Journal of Hydrology: 167-182. doi:10.1016/j.hydrol.2005.03.023.
14. "SGB-CPRM".
15. Josyane, Ronchail (2011). "Assessment of different precipitation datasets and their impacts on the water balance of the Negro River basin". Journal of Hydrology. 404 (3–4): 304–322. Bibcode:2011JHyd..404..304G. doi:10.1016/j.jhydrol.2011.04.037.
16. Théry, Hervé; Maurence, Pascale (1997). HYDROLOGIE DU BASSIN AMAZONIEN (PDF). ISBN 2-7011-1532-9.
17. Church, George Earl (1911b). "Orinoco" . In Chisholm, Hugh (ed.). Encyclopædia Britannica. Vol. 20 (11th ed.). Cambridge University Press. pp. 275–276.
18. Daum, Andreas W. (2024). Alexander von Humboldt: A Concise Biography. Trans. Robert Savage. Princeton, N.J.: Princeton University Press. p. 69. ISBN 978-0-691-24736-6.
19. Huber, Otto and Wurdack, J. J. (1984), History of botanical exploration in Territorio Federal Amazonas, Venezuela (Smithsonian contributions to botany; City of Washington: Smithsonian Institution Press) iii, 83 p.
20. "Graham Clarke". The Daily Telegraph. 2007-10-07. Retrieved 2008-07-14.
21. Hales, J., and P. Petry (2013). Rio Negro. Freshwater Ecoregions of the World. Retrieved 12 February 2013
22. 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.

References

• Goulding, M., Carvalho, M. L., & Ferreira, E. J. G. (1988). Rio Negro, Rich Life in Poor Water : Amazonian Diversity and Foodchain Ecology as seen through Fish Communities. The Hague: SPB Academic Publishing. ISBN 90-5103-016-9
• Saint-Paul, U., Berger, U., Zuanon, J., Villacorta Correa, M. A., García, M., Fabré, N. N., et al. (2000). "Fish communities in central Amazonian white- and blackwater floodplains," Environmental Biology of Fishes, 57(3), 235–250.
• Sioli, H. (1955). "Beiträge zur regionalen Limnologie des Amazonasgebietes. III. Über einige Gewässer des oberen Rio Negro-Gebietes." Arch. Hydrobiol., 50(1), 1-32.
• Wallace, A. R. (1853). A narrative of travels on the Amazon and Rio Negro, with an account of the native tribes, and observations on the climate, geology, and natural history of the Amazon Valley. London: Reeve.
• Wright, R. (2005). História indígena e do indigenismo no Alto Rio Negro. São Paulo, Brazil: UNICAMP & Instituto Socioambiental. ISBN 85-7591-042-6.