Misplaced Pages

#756243

45-753: The Tocantins is one of the largest clearwater rivers in South America. It rises in the mountainous district known as the 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 1,670 km (1,040 mi) before its confluence with the Tocantins, to which it

90-483: A capacity of 45 cubic kilometres (36,000,000 acre⋅ft) with a live volume of 32 cubic kilometres (26,000,000 acre⋅ft). The 405 by 58 metres (1,329 ft × 190 ft) Phase I power house is concrete and is fitted with an intake and penstocks . Phase I's power house contains 12 x 350 MW (470,000 hp) Francis turbine generators . An auxiliary water intake and auxiliary powerhouse also houses 2 x 22.5 MW (30,200 hp) generators. The dam

135-538: 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 ,

180-577: A friend died alongside her. Silva was a staunch protester of tropical damming, working as a regional coordinator for the Movement of Dam-Affected Peoples, and spent much of her time exposing the fact that while hydroelectric power is lauded as a sustainable energy source, the Tucuruí Dam's location meant it was not environmentally friendly. Prior to the Dam's construction, farming and mining, supported by

225-654: A low conductivity , relatively low levels of dissolved solids , typically have a neutral to slightly acidic pH and are very clear with a greenish colour. Clearwater rivers often have fast-flowing sections. The main clearwater rivers are South American and have their source in the Brazilian Plateau or the Guiana Shield . Outside South America the classification is not commonly used, but rivers with clearwater characteristics are found elsewhere. Amazonian rivers fall into three main categories: clearwater, blackwater and whitewater . This classification system

270-532: A ranch in Piratininga, São Paulo as a protest to the destruction of lands as a result of the Tucuruí Dam's construction. Through a process referred to as grilagem (translates to land-grabbing from Portuguese), which could be compared to a more violent form of gaining squatters rights in other countries, the protesters were able to occupy the land. The term ecosystem services refers to he varied benefits an ecological region provides humanity. The construction of

315-571: A result. The Tocantins watershed was, historically, an important access point for freshwater amongst the humans and animals living in the region. As a result of construction, however, the water quality of the Tocantins River Basin has been jeopardized due to discharge of industrial effluents, residues of agricultural uses, and untreated sewage disposal. The main portion Tucuruí Dam is a 78-metre-high (256 ft) and 6.9-kilometre-long (4.3 mi) concrete-gravity dam. The addition of

360-552: 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 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

405-505: A series of street demonstration organized by the Movement of Dam Affected People, Movimento dos Trabalhadores Rurais Sem Terra , and Via Campesina resulted in protesters occupying the Tucuruí plant for two days. The occupation resulted in a small win for protesters, as government officials agreed to meet with representatives if the Movement of Dam Affected People to end the protest. In 2007 Movimento dos Trabalhadores Rurais Sem Terra occupied

450-433: A single river, depending on season or heavy rains. The difference in chemistry and visibility between the various black, white and clearwater rivers result in distinct differences in flora and fauna. Although there is considerable overlap in the fauna found in the different river types, there are also many species found only in one of them. Many blackwater and clearwater species are restricted to relatively small parts of

495-729: 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 installed capacity of the 25-unit plant is 8,370 megawatts (11,220,000 hp). Phase I construction began in 1980 and ended in 1984 while Phase II began in 1998 and ended in 2010. The dam

SECTION 10

#1732765084757

540-448: 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 160 km (99 mi) above its junction with the Tocantins, it saws its way across

585-440: Is designed to support two 210 by 33 metres (689 ft × 108 ft) wide navigation locks. The Tucuruí Dam brought power to 13 million people and 60% of the power is transferred to industries which create just under 2,000 jobs. Between 25,000 and 35,000 people were removed from the future reservoir zone in the early 1980s. 14,000 people were relocated by the government. 3,750 of these people moved to new islands created by

630-670: 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

675-542: Is typically neutral to slightly acidic , but the pH can range between 4.5 and 8. In the Amazon basin, clearwater rivers flowing through regions with sediments of Tertiary age are typically highly acidic, while those flowing through sediments of Carboniferous age are closer to neutral or slightly basic . As suggested by the name, clearwater rivers are highly transparent with a typical visibility of 1.5–4 m (5–13 ft). There can be large variations, even within

720-684: 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 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

765-529: The Brazilian Plateau or the Guiana Shield . Examples of clearwater rivers originating in the Brazilian Plateau include Tapajós , Xingu , Tocantins , several large right-bank tributaries of the Madeira (notably Guaporé , Ji-Paraná and Aripuanã ) and Paraguay (although heavily influenced by its whitewater tributaries). The Tapajós and Xingu alone account for 6% and 5%, respectively, of

810-478: The $ 1.35 billion Phase II began in June 1998. This phase called for the construction of the new power house for 11 x 375 MW (503,000 hp) Francis turbines and the completion of the navigation lock-system. The new power house is located to the left of the old one and the locks are on the north side of the dam's abutments. Phase II was expected to be completed in 2006 but is behind schedule. The second power house

855-502: The Amazon, as different blackwater and clearwater systems are separated (and therefore isolated) by large whitewater sections. These "barriers" are considered a main force in allopatric speciation in the Amazon basin. Many species of fish, which often are threatened (especially by dams ), are only known from clearwater rivers. Large sections with rapids are home to specialized, rheophilic fish, as well as aquatic plants such as Podostemaceae . There are major differences in

900-464: 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

945-456: The Mojú and Caraipé earth-fill dikes increases the total length to 12,515 metres (41,060 ft). The main dam's Creager-type service spillway is the second largest in the world with a maximum capacity of 110,000 cubic metres per second (3,900,000 cu ft/s). It is controlled by 20 floodgates measuring 20 by 21 metres (66 ft × 69 ft). The reservoir impounded by the dam has

SECTION 20

#1732765084757

990-568: The Tucuruí Dam either jeopardized or destroyed a plethora of the ecosystem services the region provided before the hydroelectric dam's construction. Cultural/heritage services are those that contribute to the success of a particular community's culture and way of life. Prior to the dam's construction, multiple indigenous groups' identity was tied to the Tocantins River area in the Brazilian state of Pará which would come to be destroyed by

1035-451: The amount of macrophytes and this is mainly related to light: heavily shaded clearwater rivers have few, while those flowing through more open regions often contain many. Clearwater rivers have relatively low productivity compared to whitewater rivers, resulting in a comparably low insect abundance. Tucuru%C3%AD Dam The Tucuruí Dam (Tucuruí means "grasshopper's water", translated from Tupí language ; Portuguese : Tucuruí )

1080-482: The bid to construct the dam. Construction on Phase I began on November 24, 1975. Phase I called for the construction of the main dam, its dikes, the power house, spillway and upper portion of the navigation locks. On February 1, 1977, concrete-pouring began on site and in September 1978, the river diversion began. On September 6, 1984, the reservoir began filling and 206-days later it was at normal pool. Construction

1125-415: The dam and most of the funding was procured by Eletronorte and Brazilian institutions such as Eletrobrás, BNH, Banco do Brasil , Caixa Econômica Federal and FINAME. A smaller portion of funding came from Canadian, European and American institutions. In 1975, the consortium formed by the Brazilian companies Engevix and Themag were hired to draw up the basic and executive designs. In 1976, Camargo Correa won

1170-659: The dam. Since the dam's construction, a number of indigenous reserves, like those of the Parakanã, Pucuruí and Montanha have been flooded and the reserves of the Mãe Maria, Trocará, Krikati and Cana Brava have been cut through by transmission lines. While cultural/heritage services refers to the spaces humans inhabit, habitat services refers to animals. The river was once home to 280 species of fish, but only 178 species remain. Additionally, aquatic mammals, such as manatees, river dolphins, and amazon dolphins which once flourished in

1215-613: The entire Tocantins River Basin. In 1973, Brazilian President Emílio Médici was asked to assign funding for a dam on the Tocantins. Two options were available: the Tucuruí Dam and Santo Antonio Dam (unrelated to the Santo Antonio Dam on the Madeira river ). In 1973, the Engevix-Ecotec consortium carried out feasibility studies and the Santo Antonio Dam was ruled out in 1974. Later in 1974, the Tucuruí Dam

1260-593: 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

1305-442: 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). Clearwater river (river type) A clearwater river is classified based on its chemistry, sediments and water colour. Clearwater rivers have

1350-597: The lands which came to be flooded by the Dam, was the main way of life for peoples like the Parakan, Asurini and ParkatÍjÍ. Before construction of the dam began a study was conducted to analyze the impact the project would have on local communities in which it was determined that 900 tons of the 1,500 tons of fish that these communities relied upon for survival would no longer be accessible. Without agency in Brazilian society, these tribes were reliant upon others to advocate for their needs. This, of course, did not occur. In 2007

1395-483: The latter river type. Nevertheless, although clearwater rivers can have extremely low nutrient levels similar to blackwater, some such as the Tapajós, Xingu and Tocantins have nutrient levels that are intermediate between black and whitewater. The exact chemistry of clearwater rivers varies, but it is often very similar to rainwater, low in major nutrients with sodium as the relatively dominating chemical. The water

Tocantins River - Misplaced Pages Continue

1440-419: 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

1485-499: 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

1530-464: The region are not expected to survive spillways and other impacts the dam created, threatening the continued success of these species. Supporting services are one which help stabilize a particular ecosystem. In the wake of the dam's completion the region it inhabits underwent eutrophication, the process of soil becoming too nutrient rich, making it a breeding ground for malaria carrying mosquitos and ideal habitat for excessive aquatic plant life growth as

1575-479: The reservoir which lack adequate infrastructure. Construction of the dam attracted migrants which, along with the reservoir, significantly increased malaria and AIDS cases. The completion of Phase I in 1984 led to a large amount of unemployment among its 20,000 employees and subsequent migration from the area. The flooded area is in the Tocantins-Araguaia-Maranhão moist forests ecoregion,

1620-467: 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

1665-414: The upper Zambezi River , certain upland streams in major river basins of South and Southeast Asia, and many streams of northern Australia. In South America, clearwater rivers typically have their source and flow through regions with sandy soils and crystalline rocks . These are generally ancient, of Precambrian origin, and therefore heavily weathered, allowing relatively few sediments to be dissolved in

1710-538: The water in the Amazon basin . Examples of clearwater rivers originating in the Guiana Shield include the upper Orinoco (above the inflow of the blackwater Atabapo and whitewater Inírida – Guaviare ), Ventuari , Nhamundá , Trombetas , Paru , Araguari and Suriname . Outside South America the classification is not commonly used, but rivers with clearwater characteristics are found elsewhere, such as

1755-412: The water. This results in the low conductivity , relatively low levels of dissolved solids and clear colour typical of clearwater rivers. Sand and kaolinite are the typical sediments transported by clearwater rivers, similar to blackwater, but unlike whitewater that also transports high levels of illite and montmorillonite , resulting in a significantly higher fertility of places influenced by

1800-411: Was announced. While anti-dam protests result from a plethora of concerns, the chief concern of activists in this case was the displacement of individuals as a result of the dam's construction and operation. The Tucuruí Dam has displaced 32,000 people, completely wiping out some communities. The dam's most infamous protester, Dilma Ferreira Silva, was brutally assassinated on March 22, 2019. Her husband and

1845-648: Was approved during the President Ernesto Geisel administration. The dam was built primarily as a source of hydroelectricity and second for navigation between the upper and lower Tocantins River . The electricity was and is primarily supplied to industrial interests from the aluminum industry like Brazil's Companhia Vale do Rio Doce . Communities in Northeast Brazil would also benefit as well, such as Belém , São Luiz , Marabá , and later Eastern Amazonia. The World Bank refused to fund

Tocantins River - Misplaced Pages Continue

1890-508: Was completed 3 years behind schedule on November 10, 1984. The navigation lock that is part of the dam's design was only partially completed during Phase I with only the upper portion. The construction costs were predicted to be $ 3.6 billion but rose to over 5.5 billion by construction's end. Including interest during construction, the total cost for Phase I was $ 7.5 billion. Until 1999, Phase I produced an average of 21,428 terawatt-hours (77,140 PJ) of electricity per year. Construction on

1935-501: Was completed in April 2007 but construction on the navigation locks is behind schedule. Eletrobras is a Brazilian hydroelectric power company based in Rio de Janeiro. The 52% state owned electrical company generates enough energy to support about one third of Brazil's annual energy consumption. Protests to the dam's construction and continued operation have been rampant since the project

1980-402: Was featured in the 1985 film The Emerald Forest . The initial reconnaissance of the Tocantins River was carried out by the U.S. Bureau of Reclamation and USAID in 1964. The Amazon Energy Studies Coordination Committee was formed in 1968 and begin hydroelectric project studies in 1969. Before the committee closed, Eletrobrás commissioned further studies, called the "Tocantins Studies", on

2025-460: Was first proposed by Alfred Russel Wallace in 1853 based on water colour, but the types were more clearly defined according to chemistry and physics by Harald Sioli  [ de ] from the 1950s to the 1980s. Although many Amazonian rivers fall clearly into one of these categories, others show a mix of characteristics and may vary depending on season and flood levels. The main clearwater rivers are South American and have their source in

#756243