Editing Tocantins River

{{Short description|River in Brazil}}
{{Infobox river
| name               = Tocantins River
| native_name        ={{native name|pt|Rio Tocantins}}
| name_other         = ''Pyti'' ([[Parkatêjê language|Parkatêjê]])<ref name="Romanço-Parkatêjê"/>{{rp|59}}
| name_etymology     = 
<!---------------------- IMAGE & MAP -->
| image              = Flavio Andre PonteFernandoHenriqueCardoso Palmas TO.jpg
| image_size         = 300
| image_caption      = Tocantins River and Fernando Henrique Cardoso bridge
| map                = Tocantins watershed.png
| map_size           = 300
| map_caption        = Map of the Araguaia/Tocantins Watershed
| pushpin_map        = 
| pushpin_map_size   = 300
| pushpin_map_caption= 
<!---------------------- LOCATION -->
| subdivision_type1  = Country
| subdivision_name1  = [[Brazil]]
| subdivision_type2  = 
| subdivision_name2  = 
| subdivision_type3  = 
| subdivision_name3  = 
| subdivision_type4  = 
| subdivision_name4  = 
| subdivision_type5  = 
| subdivision_name5  = 
<!---------------------- PHYSICAL CHARACTERISTICS -->
| length             = {{convert|2,640|km|mi|abbr=on}} 
| width_min          = 
| width_avg          = 
| width_max          = 
| depth_min          = 
| depth_avg          = 
| depth_max          = 
| discharge1_location=mouth 
| discharge1_min     = 
| discharge1_avg     = {{convert|11,796|m3/s|cuft/s|abbr=on}}
| discharge1_max     = 
<!---------------------- BASIN FEATURES -->
| source1            = [[Serra da Mesa Dam|Serra da Mesa Reservoir]]
| source1_location   = [[Minaçu]], [[Goiás]]
| source1_coordinates= {{coord|13|50|03|S|48|18|16|W|type:landmark|display=inline}}
| source1_elevation  = {{Convert|443|m|ft|abbr=on}}
| mouth              = [[Marajó Bay]]
| mouth_location     = [[Igarapé-Miri]], [[Pará]]
| mouth_coordinates  = {{coord|1|45|S|49|10|W|display=inline,title}}
| mouth_elevation    = {{Convert|0|m|ft|abbr=on}}
| progression        = 
| river_system       = [[Tocantins basin]]
| basin_size         = {{convert|764,183|km2|mi2|abbr=on}}
| tributaries_left   =[[Paranã River|Paranã]], [[Do Sono River (Tocantins)|Sono River]] 
| tributaries_right  =[[Araguaia River]], [[Itacaiúnas River]] 
| custom_label       = 
| custom_data        = 
| extra              = 
}}
The '''Tocantins River''' ({{langx|pt|Rio Tocantins|link=no}} {{IPA|pt|ˈʁi.u tokɐ̃ˈtʃĩs, tu-}}, [[Parkatêjê dialect|Parkatêjê]]: ''Pyti'' [pɨˈti])<ref name="Romanço-Parkatêjê">{{cite book |last=Araújo |first=Leopoldina |date=2019 |title=Romanço Parkatêjê |location=Belém |isbn=978-85-910871-4-3}}</ref>{{rp|59}} 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 {{Convert|2450|km|abbr=on}}. 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 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 river (river type)|clearwater rivers]] in South America.<ref>{{cite news | author=Perez, M.S. | url=https://www.americanscientist.org/article/where-the-xingu-bends-and-will-soon-break | title=Where the Xingu Bends and Will Soon Break | publisher=American Scientist | access-date=1 October 2017 }}</ref>

== Course ==
It rises in the mountainous district known as the [[Pirineus State Park|Pireneus]], west of 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 {{Convert|1670|km|abbr=on}} 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 the lowlands, it breaks frequently into waterfalls and [[rapids]], or winds violently through rocky gorges, until, at a point about {{Convert|160|km|abbr=on}} above its junction with the Tocantins, it saws its way across a rocky [[dike (geology)|dyke]] for {{Convert|20|km|abbr=on}} in roaring cataracts.{{Cn|date=March 2021}}
[[File:Rio Tocantins e embarcações.JPG|thumb|Boats on the Tocantins]]
Two other tributaries, called the [[Maranhão River|Maranhão]] and [[Paranatinga]], collect an immense volume of water from the highlands which surround them, especially on 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.{{Cn|date=March 2021}}

==Fauna==

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]].<ref name=Provete>Provete, D.B. (2013). ''[http://diogoprovete.weebly.com/uploads/1/7/3/6/17367099/tocantins_river.pdf Tocantins River.]'' 1237-1239</ref>

The Tocantins River Basin has a high [[Species richness|richness]] of fish species, although it is relatively low by [[Amazon basin]] standards.<ref name=Provete/> More than 350 fish species have been registered, including more than 175 [[Endemism|endemics]].<ref name=FEW>Hales, J., and P. Petry: ''[http://www.feow.org/ecoregions/details/324 Tocantins - Araguaia]''. Freshwater Ecoregions of the World. Retrieved 26 May 2014</ref> The most species rich families are [[Characidae]] (tetras and allies), [[Loricariidae]] (pleco catfish and allies) and [[Rivulidae]] (South American killifish).<ref name=FEW/> While most species essentially are of Amazonian origin, there are also some showing a connection with the [[Paraná River|Paraná]] and [[São Francisco river]]s. 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.<ref>Garavello, J.C.; Garavello, J.P.; and Oliveira, A.K. (2010). ''[http://www.scielo.br/pdf/bjb/v70n3/14.pdf Ichthyofauna, fish supply and fishermen activities on the mid-Tocantins River, Maranhão State, Brazil.]'' Braz. J. Biol., vol. 70(3): 575-585</ref> There are several fish species that [[Fish migration|migrate]] along the Tocantins to spawn, but this has been restricted by the dams.<ref name=Provete/><ref name=FEW/> Following the construction of the massive [[Tucuruí Dam]], 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.<ref name=Provete/><ref>Lambert de Brito Ribeiro, M. C.; Petrere Junior, M.; and Juras, A. A. (2006). "Ecological integrity and fisheries ecology of the Araguaia—Tocantins River Basin, Brazil." ''Regulated Rivers: Research & Management'', vol. 11(3-4): 325–350</ref>

The [[São Domingos, Goiás|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 taxon|undescribed]] ''[[Cetopsorhamdia]]'' species and  ''[[Eigenmannia vicentespelaea]]''.<ref name=Romero2001>Romero, Aldemaro, editor (2001). ''The Biology of Hypogean Fishes.'' Developments in Environmental Biology of Fishes. {{ISBN|978-1402000768}}</ref><ref>Caserta Tencatt; L. F.; and M. Elina Bichuette (2017). Aspidoras mephisto, new species: The first troglobitic Callichthyidae (Teleostei: Siluriformes) from South America. PLoS ONE 12(3): e0171309.</ref> The last 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]]'').<ref name=Romero2001/>

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.<ref>{{citation |title=South America: Eastern extreme of the Amazon basin in Brazil (NT0170)
 |last=Sears |first=Robin |publisher=WWF: World Wildlife Fund
 |url=http://www.worldwildlife.org/ecoregions/nt0170|access-date=2017-03-25}}</ref>

== Dams ==
Downstream from 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.<ref name=Provete/> When the second phase of the Tucuruí project was completed on November 30, 2010, a system of [[Lock (water transport)|locks]] called Eclusas do Tucuruí was established with the goal of making a long extension of the river navigable.{{Cn|date=March 2021}}

In total there are seven dams on the river ([[Serra da Mesa Dam|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.<ref name=Provete/>

== Geology ==
The flat, broad valleys, composed of sand and clay, of both the Tocantins and its Araguaia branch are overlooked by steep bluffs. They are the margins of the great [[sandstone]] plateaus, from {{convert|300|to|600|m|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 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.{{Cn|date=March 2021}}

== Discharge ==
The Tocantins River records a mean discharge rate of {{Convert|13598|m3/s|abbr=on}} and a specific discharge rate of {{Convert|14.4|L/s/km2|abbr=on}}. The [[Subbasin|sub-basins]] have the following specific discharge rates: Tocantins ({{Convert|11|L/s/km2|abbr=on|disp=or}}), Araguaia ({{Convert|16|L/s/km2|abbr=on|disp=or}}), Pará ({{Convert|17|L/s/km2|abbr=on|disp=or}}) and Guamá ({{Convert|21|L/s/km2|abbr=on|disp=or}}).{{Cn|date=March 2021}}
[[File:Tocantins River.jpg|thumb|The banks of the Tocantins are rocky in some places]]

==References==
{{Reflist}}

== External links ==
{{NIE Poster|Tocantins, Rio|Tocantins River}}
* [https://web.archive.org/web/20060519081942/http://www.transportes.gov.br/bit/mapas/mapclick/hidro/bctoca.htm ''Basin map (in Portuguese)'']
*{{GEOnet2|32FA87CBE1D93774E0440003BA962ED3|Rio Tocantins }}

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[[Category:Rivers of Goiás]]
[[Category:Rivers of Maranhão]]
[[Category:Rivers of Pará]]
[[Category:Rivers of Tocantins]]