Tocantins River
Encyclopedia
The Tocantins 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 2,640 km. It is not really a branch of the Amazon River
, although usually so considered, since its waters flow into the Atlantic Ocean
alongside those of the Amazon. 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 Araguaia River
, has its extreme southern headwaters on the slopes of the Serra dos Caiapós. The Araguaia flows 1,670 km 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 waterfall
s and rapids, or winds violently through rocky gorges, until, at a point about 160 km above its junction with the Tocantins, it saws its way across a rocky dyke for 20 km 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 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.
, one of the world's largest. When the second phase of the Tucuruí project is completed, there will be a system of locks
that will make a long extension of the river navigable. The construction works on the locks have been stalled for many years due to lack of funding, but it is possible that they will be included in a massive development program launched by the Brazilian government in 2007, in which case they could be operational within about four years.
plateaus, from 300 to 600 m elevation above sea-level, through which the rivers have eroded their deep beds. Around the estuary of the Tocantins the great plateau has disappeared, to give place to 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.
River
A river is a natural watercourse, usually freshwater, flowing towards an ocean, a lake, a sea, or another river. In a few cases, a river simply flows into the ground or dries up completely before reaching another body of water. Small rivers may also be called by several other names, including...
in Brazil
Brazil
Brazil , officially the Federative Republic of Brazil , is the largest country in South America. It is the world's fifth largest country, both by geographical area and by population with over 192 million people...
, 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 2,640 km. It is not really a branch of the Amazon River
Amazon River
The Amazon of South America is the second longest river in the world and by far the largest by waterflow with an average discharge greater than the next seven largest rivers combined...
, although usually so considered, since its waters flow into the Atlantic Ocean
Atlantic Ocean
The Atlantic Ocean is the second-largest of the world's oceanic divisions. With a total area of about , it covers approximately 20% of the Earth's surface and about 26% of its water surface area...
alongside those of the Amazon. It flows through four Brazilian states (Goiás
Goiás
Goiás is a state of Brazil, located in the central part of the country. The name Goiás comes from the name of an indigenous community...
, Tocantins
Tocantins (state)
Tocantins is one of the states of Brazil. . The state was formed in 1988 out of the northern part of Goiás, and construction began on the capital, Palmas, in 1989, in contrast to most of the other cities in the state which date back to the Portuguese colonial period...
, Maranhão
Maranhão
Maranhão is a northeastern state of Brazil. To the north lies the Atlantic Ocean. Maranhão is neighbored by the states of Piauí, Tocantins and Pará. The people of Maranhão have a distinctive accent...
and Pará
Pará
Pará is a state in the north of Brazil. It borders the Brazilian states of Amapá, Maranhão, Tocantins, Mato Grosso, Amazonas and Roraima. To the northwest it also borders Guyana and Suriname, and to the northeast it borders the Atlantic Ocean. The capital is Belém.Pará is the most populous state...
) and gives its name to one of Brazil's newest states, formed in 1988 from what was until then the northern portion of Goiás.
Course
It rises in the mountainous district known as the Pireneus, west of the Federal District, but its western tributaryTributary
A tributary or affluent is a stream or river that flows into a main stem river or a lake. A tributary does not flow directly into a sea or ocean...
, the Araguaia River
Araguaia River
The Araguaia River or, in Portuguese, Rio Araguaia is one of the major rivers of Brazil, and the principal tributary of the Tocantins. It has a total length of approximately 2,627 km. Araguaia means "river of macaws" in the Tupi language....
, has its extreme southern headwaters on the slopes of the Serra dos Caiapós. The Araguaia flows 1,670 km before its confluence
Confluence (geography)
In geography, a confluence is the meeting of two or more bodies of water. It usually refers to the point where two streams flow together, merging into a single stream...
with the Tocantins, to which it is almost equal in volume. Besides its main tributary, the Rio das Mortes
Rio das Mortes
The Rio das Mortes is a river of Mato Grosso state in western Brazil. It has a length of 278 km.-References:*...
, the Araguaia has twenty smaller branches, offering many miles of canoe
Canoe
A canoe or Canadian canoe is a small narrow boat, typically human-powered, though it may also be powered by sails or small electric or gas motors. Canoes are usually pointed at both bow and stern and are normally open on top, but can be decked over A canoe (North American English) or Canadian...
navigation. In finding its way to the lowlands, it breaks frequently into waterfall
Waterfall
A waterfall is a place where flowing water rapidly drops in elevation as it flows over a steep region or a cliff.-Formation:Waterfalls are commonly formed when a river is young. At these times the channel is often narrow and deep. When the river courses over resistant bedrock, erosion happens...
s and rapids, or winds violently through rocky gorges, until, at a point about 160 km above its junction with the Tocantins, it saws its way across a rocky dyke for 20 km in roaring cataracts.
Two other tributaries, called the Maranhão
Maranhão River
-References:*...
and Paranatinga
Paranatinga
Paranatinga is a town and municipality in the state of Mato Grosso in the Central-West Region of Brazil.-References:...
, 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.
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 damTucurui dam
The Tucuruí Dam is a concrete gravity dam on the Tocantins River located on the Tucuruí County in the State of Pará, Brazil. The main purpose of the dam is hydroelectric power production and navigation. It is the first large-scale hydroelectric project in the Brazilian Amazon rainforest. The...
, one of the world's largest. When the second phase of the Tucuruí project is completed, there will be a system of locks
Lock (water transport)
A lock is a device for raising and lowering boats between stretches of water of different levels on river and canal waterways. The distinguishing feature of a lock is a fixed chamber in which the water level can be varied; whereas in a caisson lock, a boat lift, or on a canal inclined plane, it is...
that will make a long extension of the river navigable. The construction works on the locks have been stalled for many years due to lack of funding, but it is possible that they will be included in a massive development program launched by the Brazilian government in 2007, in which case they could be operational within about four years.
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 sandstoneSandstone
Sandstone is a sedimentary rock composed mainly of sand-sized minerals or rock grains.Most sandstone is composed of quartz and/or feldspar because these are the most common minerals in the Earth's crust. Like sand, sandstone may be any colour, but the most common colours are tan, brown, yellow,...
plateaus, from 300 to 600 m elevation above sea-level, through which the rivers have eroded their deep beds. Around the estuary of the Tocantins the great plateau has disappeared, to give place to a part of the forest-covered, half submerged alluvial plain
Alluvial plain
An alluvial plain is a relatively flat landform created by the deposition of sediment over a long period of time by one or more rivers coming from highland regions, from which alluvial soil forms...
, which extends far to the north-east and west. The Pará River
Pará River
The Pará River is the southern arm of the mouth of the Amazon River. It flows round the west and south of the island of Marajó. It takes some water from the main Amazon, however much of its power comes from the Tocantins River flowing from the south. The state capital of Pará, Belém, is located on...
, 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
Marajó
Marajó is an island located at the mouth of the Amazon River in Brazil. It is part of the state of Pará.- Geography :With a land area of 40,100 km² , which compares to the size of Switzerland, it is the largest island to be completely surrounded by freshwater in the world...
into the river Para, it is only through tortuous, natural canals, which are in no sense outflow channels of the Amazon.