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22-537: The Araguaia River comes from Goiás-Mato Grosso south borders. From there it flows northeast to a junction with the Tocantins near the town of São João. Along its course, the river forms the border between the states of Goiás , Mato Grosso , Tocantins and Pará . Roughly in the middle of its course the Araguaia splits into a fork (with the western stream retaining the name Araguaia and the eastern one being called

44-598: A connection with the Paraná and São Francisco rivers . The Tocantins and these two rivers flow in different directions, but all have their source in the Brazilian Plateau in a region where a low watershed allows some exchange between them. There are several fish species that migrate along the Tocantins to spawn, but this has been restricted by the dams. Following the construction of the massive Tucuruí Dam ,

66-420: A high richness of fish species, although it is relatively low by Amazon basin standards. More than 350 fish species have been registered, including more than 175 endemics . The most species rich families are Characidae (tetras and allies), Loricariidae (pleco catfish and allies) and Rivulidae (South American killifish). While most species essentially are of Amazonian origin, there are also some showing

88-703: Is a river in Brazil , the central fluvial artery of the country. In the Tupi language , its name means " toucan 's beak" ( Tukã for "toucan" and Ti for "beak"). It runs from south to north for about 2,450 km (1,520 mi). While sometimes included in definitions of the Amazon basin, the Tocantins is not a branch of the Amazon River , since its waters flow into the Atlantic Ocean via an eastern channel of

110-599: Is navigable to Pará . Other important tributaries include the Bonito , Garcas , Tapirape and the Formoso or Cristalino on the west, and the Pitombas , Claro , Vermelho , Tucupa and Chavante on the east. It was explored in part by Henri Coudreau in 1897. From 1972 to 1974 this region was the scene of a conflict between left-wing guerrilla movements and forces supporting the then military dictatorship . Among

132-562: Is spoken by 12 individuals in Terra Indígena Mãe Maria ( Bom Jesus do Tocantins , Pará ). It is closely related to Kỳikatêjê , spoken by another Timbira group in the same reservation. Parkatêjê has been described and documented by Leopoldina Araújo and, more recently, by other researchers from the Federal University of Pará . Parkatêjê (and Kỳikatêjê) differ from all other Timbira varieties in lacking

154-672: Is the only known cave-adapted knifefish and one of only two known non-catfish in caves of the South American mainland (the other is the characid Stygichthys typhlops ). In its lower reaches, the Tocantins separates the Tocantins–Araguaia–Maranhão moist forests ecoregion to the east from the Xingu–Tocantins–Araguaia moist forests ecoregion to the west. It acts as a barrier that prevents dispersal of flora and fauna between these ecoregions. Downstream from

176-697: The Araguaia Tocantins Basin ) covers approximately 9.5% of Brazil's national territory. This area is an integral part of the Amazon biome ; however, the Araguaia River is not a tributary of the Amazon. "Araguaia" means "River of the macaws " in the native Tupi language . Its principal tributary is the Rio das Mortes , which rises in the Serra de São Jerônimo , near Cuiabá , Mato Grosso, and

198-596: The Amazon Delta , alongside those of the Amazon proper. It flows through four Brazilian states ( Goiás , Tocantins , Maranhão , and Pará ) and gives its name to one of Brazil's newest states, formed in 1988 from what was until then the northern portion of Goiás . The Tocantins is one of the largest clearwater rivers in South America. It rises in the mountainous district known as the Pireneus , west of

220-745: The Javaés River ). These later reunite, forming the Ilha do Bananal , the world's largest river island. The vein of the Javaés forms a broad inland where it pours back into the main Araguaia, a 100,000 hectare expanse of igapós or flooded forest, blackwater river channels, and oxbow lakes called Cantão , protected by the Cantão State Park . It is one of the biologically richest areas of the eastern Amazon, with over 700 species of birds, nearly 300 species of fish, large populations of species such as

242-596: The giant otter , the black caiman , the pirarucú , one of the world's largest freshwater fish, and the Araguaian river dolphin (or Araguaian boto), all occurring within a large area. A large portion of the Araguaia's course is navigable all year, but the river below the Cantão wetlands is interrupted by rapids. The middle and lower basin of the river is in the Xingu–Tocantins–Araguaia moist forests ecoregion. The combined watershed of Araguaia and Tocantins rivers (named

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264-460: The Araguaia basin has been extreme during the last four decades. As a consequence, strong linear erosion has produced thousand of gullies just in the upper Araguaia basin, and the river mainstem suffered strong sedimentation and fluvial metamorphism (changes in its channel pattern). Tocantins River The Tocantins River (Portuguese: Rio Tocantins Portuguese pronunciation: [ˈʁi.u tokɐ̃ˈtʃĩs, tu-] , Parkatêjê : Pyti [pɨˈti])

286-518: The Araguaia confluence, in the state of Pará, the river used to have many cataracts and rapids, but they were flooded in the early 1980s by the artificial lake created by the Tucuruí Dam , one of the world's largest. When the second phase of the Tucuruí project was completed on November 30, 2010, a system of locks called Eclusas do Tucuruí was established with the goal of making a long extension of

308-565: The Federal District, but its western tributary, the Araguaia River , has its extreme southern headwaters on the slopes of the Serra dos Caiapós . The Araguaia flows 1,670 km (1,040 mi) before its confluence with the Tocantins, to which it is almost equal in volume. Besides its main tributary, the Rio das Mortes , the Araguaia has twenty smaller branches, offering many miles of canoe navigation. In finding its way to

330-597: The flow of the river changed. Some species have been adversely affected and there has been a substantial reduction in species richness in parts of the river. The São Domingos karst in the upper Tocantins basin is home to an unusually high number of cavefish species (more than any other region in the Americas): Ancistrus cryptophthalmus , several Ituglanis species, Pimelodella spelaea , Aspidoras mephisto , an undescribed Cetopsorhamdia species and Eigenmannia vicentespelaea . The last

352-476: The following specific discharge rates: Tocantins (11 L/s/km or 1.0 cu ft/s/sq mi), Araguaia (16 L/s/km or 1.5 cu ft/s/sq mi), Pará (17 L/s/km or 1.6 cu ft/s/sq mi) and Guamá (21 L/s/km or 1.9 cu ft/s/sq mi). Parkat%C3%AAj%C3%AA dialect Parkatêjê , or Pará Gavião , is a Timbira variety of the Jê language family of Brazil . It

374-492: The lowlands, it breaks frequently into waterfalls and rapids , or winds violently through rocky gorges, until, at a point about 160 km (99 mi) above its junction with the Tocantins, it saws its way across a rocky dyke for 20 km (12 mi) in roaring cataracts. Two other tributaries, called the Maranhão and Paranatinga , collect an immense volume of water from the highlands which surround them, especially on

396-419: The margins of the great sandstone plateaus, from 300 to 600 metres (980 to 1,970 ft) elevation above sea-level, through which the rivers have eroded their deep beds. Around the estuary of the Tocantins the great plateau has disappeared, having been replaced by a part of the forest-covered, half submerged alluvial plain , which extends far to the north-east and west. The Pará River , generally called one of

418-547: The most important settlements on the banks of the Araguaia River are (in a downstream order): Several parts of the river's course are protected by national parks and other reserves like the Emas National Park and the Araguaia National Park . The Araguaia has "beaches" - bright sandy banks that seam the stream from May to October. Deforestation and expansion of cattle ranching and agriculture in

440-502: The mouths of the Amazon, is only the lower reach of the Tocantins. If any portion of the waters of the Amazon runs round the southern side of the large island of Marajó into the river Para, it is only through tortuous, natural canals, which are in no sense outflow channels of the Amazon. The Tocantins River records a mean discharge rate of 13,598 m /s (480,200 cu ft/s) and a specific discharge rate of 14.4 L/s/km (1.32 cu ft/s/sq mi). The sub-basins have

462-469: The river navigable. In total there are seven dams on the river ( Serra da Mesa dam , Cana Brava dam, São Salvador dam, Peixe Angical dam, Luiz Eduardo Magalhães (Lajeado) dam, Estreito dam, and Tucuruí dam), of which the largest are the Tucuruí and the Serra da Mesa dam. The flat, broad valleys, composed of sand and clay, of both the Tocantins and its Araguaia branch are overlooked by steep bluffs. They are

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484-490: The south and south-east. Between the latter and the confluence with the Araguaia, the Tocantins is occasionally obstructed by rocky barriers which cross it almost at a right angle. The Tocantins basin (which includes the Araguaia River ) is the home of several large aquatic mammals such as Amazonian manatee , Araguaian river dolphin and tucuxi , and larger reptiles such as black caiman , spectacled caiman and yellow-spotted river turtle . The Tocantins River Basin has

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