Madeira River
The Madeira River is a major waterway in South America
South America
South America is a continent situated in the Western Hemisphere, mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere. The continent is also considered a subcontinent of the Americas. It is bordered on the west by the Pacific Ocean and on the north and east...

, approximately 3,250 km (2,020) miles long The Madeira is the biggest tributary of the Amazon
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...

. A map from Emanuel Bowen
Emanuel Bowen
Emanuel Bowen was an English map engraver, who worked for George II of England and Louis XV of France as a geographerHe published a 'Complete Atlas of Geography,' 1744-7; an 'English Atlas, with a new set of maps,' 1745; a 'Complete Atlas .....

 in 1747, held by the David Rumsey Map Collection
David Rumsey Historical Map Collection
The David Rumsey Historical Map Collection is one of the world's largest private map collections. It has some 150,000 maps and cartographic items...

, refers to the Madeira by the pre-colonial, indigenous name Cuyari:

"The River of Cuyari, called by the Portuguese Madeira or the Wood River, is formed by two great rivers, which join near its mouth. It was by this River, that the Nation of Topinambes passed into the River Amazon."


The mean inter-annual precipitations on the great basins vary from 750 to 3000 mm (29.5 to 118.1 in), the entire upper Madeira basin receiving 1705 millimetres (67.1 in). The greatest extremes of rainfall are between 490 to 7000 mm (19.3 to 275.6 in). At its head, the Madeira on its own is still one of the largest rivers of the world, with a mean inter-annual discharge of 18000 m3/s, i.e. 536 cubic kilometres (128.6 cu mi)/yr, approximately half the discharge of the Congo River
Congo River
The Congo River is a river in Africa, and is the deepest river in the world, with measured depths in excess of . It is the second largest river in the world by volume of water discharged, though it has only one-fifth the volume of the world's largest river, the Amazon...

. The mean inter-annual contribution of the Bolivian Andes is 4170 m3/s, i.e. 132 cubic kilometres (31.7 cu mi)yr, representing 25% of the discharge of the entire upper Madeira basin. On the further course towards the Amazon, the mean discharge of the Madeira increases up to 31200 m3/s.


Between Guajará-Mirim
Guajará-Mirim is a municipality in the Brazilian state of Rondônia. It is located at an altitude of 128 meters. Its population was 41,467 and its area is 24,856 km².It lies along the Mamoré River, just across the Bolivian border town of Guayaramerín...

 and the falls of Teotônio, the Madeira receives the drainage of the north-eastern slopes of the Andes
The Andes is the world's longest continental mountain range. It is a continual range of highlands along the western coast of South America. This range is about long, about to wide , and of an average height of about .Along its length, the Andes is split into several ranges, which are separated...

 from Santa Cruz de la Sierra
Santa Cruz de la Sierra
Santa Cruz de la Sierra, commonly known as Santa Cruz, is the capital of the Santa Cruz department in eastern Bolivia and the largest city in the country...

 to Cuzco
Cusco Region
Cusco is a region in Peru. It is bordered by the Ucayali Region on the north; the Madre de Dios and Puno regions on the east; the Arequipa Region on the south; and the Apurímac, Ayacucho and Junín regions on the west...

, the whole of the south-western slope of 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...

ian Mato Grosso
Mato Grosso
Mato Grosso is one of the states of Brazil, the third largest in area, located in the western part of the country.Neighboring states are Rondônia, Amazonas, Pará, Tocantins, Goiás and Mato Grosso do Sul. It also borders Bolivia to the southwest...

 and the northern slope of the Chiquitos sierras. In total, the catchment area is 850,000 km2, almost equal in area to France
The French Republic , The French Republic , The French Republic , (commonly known as France , is a unitary semi-presidential republic in Western Europe with several overseas territories and islands located on other continents and in the Indian, Pacific, and Atlantic oceans. Metropolitan France...

 and Spain
Spain , officially the Kingdom of Spain languages]] under the European Charter for Regional or Minority Languages. In each of these, Spain's official name is as follows:;;;;;;), is a country and member state of the European Union located in southwestern Europe on the Iberian Peninsula...

 combined. The waters flow into the Madeira from many large rivers, the principal of which, (from east to west), are the Guaporé
Guaporé may refer to:*Guaporé River in Brazil/Bolivia*Guaporé, Rio Grande do Sul in Brazil*The former name of Rondônia...

 or Itenez, the Baures
Baures is a town in Iténez Province, Beni Department, in northern Bolivia. It is the capital of Baures Municipality..-External links:*...

 and Blanco
Blanco River
The Blanco River is a river in the Hill Country of Texas in the United States.-Course:The primary source for the river is a series of springs in northern Kendall County. The river flows generally eastward for through Kendall County, Blanco County and Hays County...

, the Itonama or San Miguel, the Mamoré
The Mamoré is a large river in Bolivia and Brazil, which unites with the Beni to form the Madeira, one of the largest tributaries of the Amazon. It rises on the northern slope of the Sierra de Cochabamba, east of the city of Cochabamba, and is known as the Chimoré down to its junction with the...

, Beni
Beni River
The Beni River is a river in the north of Bolivia.It rises north of La Paz and flows northeast through the pampas. One of the tributary rivers is Tuichi River in the Madidi National Park. Tuichi River joins the Beni River upstream from the town Rurrenabaque. South of Rurrenabaque, Río Beni runs...

, and Mayutata or Madre de Dios
Madre de Dios River
The Madre de Dios River, homonymous to the Peruvian region it runs through, then becomes the Beni River in Bolivia and then turns northward into Brazil, where it is called the Madeira River...

, all of which are reinforced by numerous secondary but powerful affluents. The climate of the upper catchment area varies from humid in the western edge with the origin of the river's main stem by volume (Río Madre de Dios, Río Beni) to semi arid in the southernmost part with the andine headwaters of the main stem by length (Río Caine, Río Rocha, Río Grande
Río Grande (Bolivia)
The Río Grande in Bolivia rises on the southern slope of the Sierra de Cochabamba, east of the city of Cochabamba, at . At its source it is known as the Río Rocha and crosses the Cochabamba valley basin in a westerly direction...

, Mamoré).

All of the upper branches of the river Madeira find their way to the falls across the open, almost level Mojos and Beni
Beni Department
Beni, sometimes El Beni, is a northeastern department of Bolivia, in the lowlands region of the country. It is the second largest department in the country , covering 213,564 square kilometers , and it was created by supreme decree on November 18, 1842 during the administration of General José...

 plains, 90000 km² (34,749.2 sq mi) of which are yearly flooded to an average depth of about 3 foot (0.9144 m) for a period of from three to four months.

The falls of Teotônio and of San Antonio are exceeding the more famous Boyoma Falls
Boyoma Falls
Boyoma Falls, formerly known as Stanley Falls, consists of seven cataracts, each no more than 15' high, extending over more than along a curve of the Lualaba River between the river port towns of Ubundu and Kisangani/Boyoma in the Orientale region of the Democratic Republic of the Congo.At the...

 in Africa by volume and total drop. From these rapids, the Madeira flows northward forming the border between Bolivia and Brazil for approximately 100 km (62.1 mi). Below the confluence of the Rio Abunã
Abuna River
The Abuna River is a river in South America. As a part of the Amazon Basin, it forms part of the border between northern Bolivia and north-western Brazil....

, the Madeira meanders north-eastward through the Rondônia
Rondônia is a state in Brazil, located in the north-western part of the country. To the west is a short border with the state of Acre, to the north is the state of Amazonas, in the east is Mato Grosso, and in the south is Bolivia. Its capital is Porto Velho. The state was named after Candido Rondon...

 and Amazonas states of north west Brazil to its junction with the Amazon
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...

. At its mouth is Ilha Tupinambaranas
Ilha Tupinambarana is the name of a former fluvial island bordered by rivers of the Amazon system in eastern Amazonas, Brazil. Today, it has been split into four completely separate parts by natural channels, just like those isolating it from the mainland--it is no longer one island, but four...

, an extensive marshy region formed by the Madeira’s distributaries.


The Madeira river rises more than 15 m (50 ft) during the rainy season, and ocean vessels may ascend it to the Falls of San Antonio, near Porto Velho
Porto Velho
Porto Velho is the capital of the Brazilian state of Rondônia, in the upper Amazon River basin. The population is estimated to be 426,558 people...

, Brazil, 1070 km (664.9 mi) above its mouth; but in the dry months, from June to November, it is only navigable for the same distance for craft drawing about 2 m (from 5 to 6 feet) of water. The Madeira-Mamoré Railroad
Madeira-Mamoré Railroad
The Madira-Mamoré Railroad is a railroad built in the Brazilian state of Rondonia between 1907 and 1912. The railroad links the Brazilian cities of Porto Velho and Guajará-Mirim. It became known as the "Devil's Rail-road" because thousands of construction workers died from tropical diseases and...

 runs in a 365 km (226.8 mi) loop around the unnavigable section to Guajará-Mirim
Guajará-Mirim is a municipality in the Brazilian state of Rondônia. It is located at an altitude of 128 meters. Its population was 41,467 and its area is 24,856 km².It lies along the Mamoré River, just across the Bolivian border town of Guayaramerín...

 on the Mamoré River.

Two large dams (see below) are under construction as part of the IIRSA regional integration project. The dam projects include large ship-locks capable of moving ocean going vessels between the impounded reservoir and the downstream river. If the project is completed, "more than 4,000 km of waterways upstream from the dams in Brazil, Bolivia, and Peru would become navigable.".


A subspecies of Boto
The Amazon river dolphin, alternatively Bufeo, Bufeo Colorado, Boto Cor de Rosa, Boutu, Nay, Tonina, or Pink Dolphin , is a freshwater river dolphin endemic to the Orinoco, Amazon and Araguaia/Tocantins River systems of Brazil, Bolivia, Peru, Ecuador, Colombia and Venezuela...

 (Amazon River Dolphin) is known to inhabit the Madeira river system.


In July 2007, plans have been approved by the Brazilian Government to construct two hydroelectric dams
Hydropower, hydraulic power, hydrokinetic power or water power is power that is derived from the force or energy of falling water, which may be harnessed for useful purposes. Since ancient times, hydropower has been used for irrigation and the operation of various mechanical devices, such as...

 on the Madeira River, the Santo Antonio Dam
Santo Antônio Dam
The Santo Antônio Dam is an under construction hydroelectric dam on the Madeira River southwest of Porto Velho in the state of Rondônia, Brazil....

 near Porto Velho and the Jirau Dam
Jirau Dam
The Jirau Dam is a hydroelectric dam currently under construction on the Madeira River in the state of Rondônia, Brazil.The dam is part of a planned four power plant Madeira river hydroelectric complex, which will consist of two dams in Brazil , a third on the border of Brazil and Bolivia,...

about 100km downstream. Both the Jirau and Santo Antonio dams are run-of-the-river projects that do not impound a large reservoir. Both dams also feature significant environmental re-mediation efforts (such as fish ladders). As a consequence, there has not been strong environmental opposition to the implementation of the Madeira river complex. However, critics point out that if the fish ladders fail, "several valuable migratory fish species could suffer near-extinction as a result of the Madeira dams."

There are also concerns with deforestation and pressure on conservation areas and indigenous peoples' territories.
The Worldwatch institute has also criticized the fast-track approval process for "kindler, gentler dams with smaller reservoirs, designed to lessen social and environmental impacts", claiming that no project should "fast-track the licensing of new dams in Amazonia and allow projects to circumvent Brazil's tough environmental laws".
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