Solimões River
Name in Brazil for the upper Amazon River
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Solimões (Portuguese pronunciation: [soliˈmõjs]) is the name often given to the upper stretch of the Amazon River in Brazil, from its confluence with the Rio Negro near Manaus upstream to the tri-border area shared by Brazil, Peru, and Colombia. The Solimões flows for about 1,600 to 1,700 kilometres (990 to 1,060 miles) through a floodplain that reaches roughly 40 to 80 kilometres (25 to 50 miles) wide in places.[1]


Use of the name Solimões for the upper Amazon is mostly confined to Brazilian speakers of Portuguese; the rest of the world refers to both the upper and lower portions of the river simply as the Amazon.
Etymology
The name Solimões derives from an Amazonian Indigenous people whom Spanish and Portuguese chroniclers encountered during the era of European exploration; lacking detailed knowledge of the river, chroniclers used local names to distinguish its stretches.[2] This people, recorded as living along the river between the present-day municipalities of Coari and Anamã, were called the Yurimaguas by 16th-century chroniclers; the Jesuit missionary Samuel Fritz undertook their conversion in that period.[3] Their name appears in a number of variant spellings across chroniclers' accounts, including Soriman,[citation needed] Joriman,[4] Sorimão,[5] and Sorimões.[3] In Portuguese these forms were further rendered as Solimão and Soliemoens, giving rise to the modern name of the river and of the region it drains.
The precise reasoning behind the name remains uncertain. One proposed derivation traces Sorimão, Sorimões, and Solimões to the Latin word sublimatum, in reference to a poison the Yurimaguas were said to apply to the tips of arrows and darts.[2] Seventeenth-century chroniclers, including Cristóbal de Acuña in 1641, described the Yurimaguas as one of the more warlike peoples along the river, with densely populated settlements along its banks, and their poisoned arrowheads have been cited as a possible source of the river's name.[2]
Geography
The Amazon/Solimões river just above its confluence with the Rio Negro is already by far the largest river in the world, even though its two largest tributaries — the Negro and the Madeira River — have not yet contributed to its flow volume.
The Solimões portion of the Amazon River lies entirely within the Brazilian state of Amazonas, and part of the state is often referred to as the "Solimões region." Along its course the river passes the municipalities of Tabatinga, São Paulo de Olivença, Amaturá, Santo Antônio do Içá, Tonantins, Jutaí, Fonte Boa, Tefé, Coari, Codajás, Anamã, Anori, and Manacapuru before reaching Manaus, where its confluence with the Rio Negro marks the point at which the river again takes the name Amazon. The ecoregion of the Solimões River drainage basin is entirely tropical rainforest.
Course and hydrology
The Solimões is an anastomosed river, meaning it is divided into long, relatively stable channels that rejoin farther downstream.[6] The course of the river and the extent of its floodplains are largely controlled by tectonic lineaments, with northwest–southeast and southwest–northeast trends predominating, alongside less common north–south and west–east trends.[6] Where these lineaments intersect, they form low-lying, roughly diamond-shaped depressions that are occupied by floodplains, in places reaching up to 40 kilometres (25 miles) wide.[6] The elevated terrain surrounding the river corresponds geologically to the Cretaceous-age Alter do Chão sedimentary formation.[6]
Studies of the river's Quaternary history indicate that a landscape of terra firme interspersed with extensive várzea forest already existed around the Solimões roughly 250,000 years ago.[7] A newer generation of terra firme is thought to have formed approximately 35,000 to 45,000 years ago as river channels cut down through the landscape, considerably reducing the extent of várzea forest.[7]
Tributaries
Going downstream from Tabatinga to Manaus, the Solimões receives numerous tributaries, several of which are themselves major Amazonian rivers.
| Tributary | Receiving river | Country/countries | Length | Source coordinates |
|---|---|---|---|---|
| Javari River | Solimões (right bank) | Peru – Brazil | 1,050 km (650 mi) | 7°08′S 73°49′W |
| Curuçá River | Javari | Brazil | 530 km (330 mi) | 6°42′S 72°42′W |
| Ituí River | Javari | Brazil | 480 km (300 mi) | 6°54′S 72°10′W |
| Jandiatuba River | Solimões (right bank) | Brazil | 500 km (310 mi) | 6°05′S 70°41′W |
| Putumayo River (Içá) | Solimões (right bank) | Colombia – Ecuador – Peru – Brazil | 1,610 km (1,000 mi) | 1°15′N 76°55′W |
| Igara Paraná River | Putumayo | Colombia | 430 km (270 mi) | 0°24′S 73°39′W |
| Jutaí River | Solimões (right bank) | Brazil | 1,050 km (650 mi) | 6°18′S 70°49′W |
| Zinho River | Jutaí | Brazil | 430 km (270 mi) | 5°21′S 67°55′W |
| Bia River | Jutaí | Brazil | 470 km (290 mi) | 5°48′S 68°22′W |
| Mutum River | Jutaí | Brazil | 320 km (200 mi) | 6°00′S 68°50′W |
| Juruá River | Solimões (right bank) | Peru – Brazil | 3,100 km (1,900 mi) | 10°09′S 73°15′W |
| Gregório River | Juruá | Brazil | 350 km (220 mi) | 8°59′S 72°04′W |
| Japurá River (Caquetá) | Solimões (left bank) | Colombia – Brazil | 2,820 km (1,750 mi) | 1°55′N 76°40′W |
| Apaporis River | Japurá-Caquetá | Colombia – Brazil[a] | 770 km (480 mi) | 1°00′N 72°20′W |
| Cahuinari River | Japurá-Caquetá | Colombia | 400 km (250 mi) | 0°35′S 72°54′W |
| Yarí River | Japurá-Caquetá | Colombia | 530 km (330 mi) | 2°37′N 74°55′W |
| Caguán River | Japurá-Caquetá | Colombia | 470 km (290 mi) | 2°38′N 74°59′W |
| Tefé River | Solimões (right bank) | Brazil | 450 km (280 mi) | 5°44′S 66°32′W |
| Coari River/Lake Coari | Solimões (right bank) | Brazil | 530 km (330 mi) | 6°12′S 66°31′W |
| Badajós River | Solimões | Brazil | 220 km (140 mi) | 3°44′07″S 62°17′15″W |
| Purus River | Solimões (right bank) | Peru – Brazil | 3,379 km (2,100 mi) | 10°50′S 72°28′W |
| Ipixuna River | Purus | Brazil | 370 km (230 mi) | 7°59′S 63°27′W |
| Tapauá River | Purus | Brazil | 640 km (400 mi) | 7°10′S 67°45′W |
| Mucuim River | Purus | Brazil | 350 km (220 mi) | 8°51′S 64°28′W |
| Ituxi River | Purus | Brazil | 640 km (400 mi) | 10°07′S 67°35′W |
| Sepatini River | Purus | Brazil | — | 8°47′S 67°02′W |
| Pauini River | Purus | Brazil | 450 km (280 mi) | 8°26′S 69°38′W |
| Acre River | Purus | Peru – Brazil – Bolivia | 680 km (420 mi) | 10°56′S 70°31′W |
| Iaco River | Purus | Peru – Brazil | 480 km (300 mi) | 10°57′S 71°0′W |
| Chandless River | Purus | Peru – Brazil | 370 km (230 mi) | 10°57′S 71°35′W |
| Manacapuru River | Solimões (left bank) | Brazil | 171 km (106 mi) | 3°16′42″S 60°51′10″W |
- The Apaporis River does not flow through Brazil, but its lower course forms a natural boundary of less than 50 km (31 mi) between Colombia and Brazil.