Table of Contents

Etymology
History
Geological history
Pre-Columbian era
Arrival of Europeans
Exploration
Scientific exploration
Post-colonial exploitation and settlement
20th-century development
Course
Origins
The Upper Amazon or Solimões
The Lower Amazon
Mouth
Lack of bridges
Dispute regarding length
Watershed
Discharge
[[Amazon Delta]]
Santarém
Óbidos
Itacoatiara
Sediment load
Flooding
Geology
Protected areas
Flora and fauna
Flora
Fauna
Challenges
Major tributaries
List of major tributaries
List by length
List by inflow to the Amazon
See also
Notes
References
Bibliography
External links

Amazon River

NameAmazon River
Name Other«Rio Amazonas», «Río Amazonas»
Image
Image Size250
Image CaptionSatellite image of the Amazon Delta
Map
Map Size250
Map CaptionAmazon River and its drainage basin
Pushpin Map Size250
Subdivision Type1Country
Subdivision Name1Peru, Colombia, Brazil
Subdivision Type5Cities
Subdivision Name5Iquitos (Peru); Leticia (Colombia);
Tabatinga (Brazil); Tefé (Brazil);
Itacoatiara (Brazil) Parintins (Brazil);
Óbidos (Brazil); Santarém (Brazil);
Almeirim (Brazil); Macapá (Brazil);
Manaus (Brazil)
Length3,750km (Amazon–Ucayali–Tambo–Ené–Apurímac 6,400km – 6,500km (Amazon–Marañón 5,700km
Width Min700m (Upper Amazon); 1.5km (Itacoatiara, Lower Amazon)
Width Avg3km (Middle Amazon); 5km (Lower Amazon)
Width Max10-14km (Lower Amazon); 340km (estuary)
Depth Avg15-45m (Middle Amazon); 20-50m (Lower Amazon)
Depth Max150m (Itacoatiara); 130m (Óbidos)
Discharge2 LocationNear mouth
Discharge2 Avg(without Tocantins) 206,000-215,000m3/s
Source1Apurímac River, Mismi Peak
Source1 LocationArequipa Region, Peru
Source1 Coordinates15°31′04″S, 71°41′37″W
Source1 Elevation5,220m
MouthAtlantic Ocean
Mouth LocationBrazil
Mouth Coordinates0°42′28″N, 50°5′22″W
River SystemAmazon River
Basin Size(with Tocantins) 6,743,000sqkm–7,000,000sqkm (5,956,000–6,112,000 km2 without Tocantins)
Tributaries LeftMarañón, Nanay, Napo, Ampiyaçu, Putumayo, Japurá, Badajós, Manacapuru, Rio Negro, Urubu, Uatumã, Nhamundá, Trombetas, Maicurú, Curuá, Paru, Jari
Tributaries RightUcayali, Jandiatuba, Javary, Jutai, Juruá, Tefé, Coari, Purús, Madeira, Paraná do Ramos, Tapajós, Curuá-Una, Xingu, Pará, Tocantins, Acará, Guamá
Discharge1 LocationAmazon Delta
Discharge1 Min180,000m3/s
Discharge1 Avg(with Tocantins) (Period: 2003–2015) 230,000m3/s
Discharge1 Max340,000m3/s
Discharge3 LocationSantarém
Discharge3 Min(Period: 1998–2023) 82,160m3/s
Discharge3 Avg(Period: 1971–2000) 191,624m3/s
Discharge3 Max(Period: 1998–2023) 298,400m3/s
Discharge4 LocationÓbidos
Discharge4 Avg(Period: 1903–2023) 165,829.6m3/s
Discharge4 Min(Period: 1903–2023) 95,000m3/s
Discharge4 Max(Period: 1903–2023) 260,000m3/s
Discharge5 LocationManacapuru
Discharge5 Avg(Period: 1997–2015) 105,720m3/s

Topography of the Amazon River Basin

The Amazon River (ukˈæməzən, usˈæməzɒn; «rio Amazonas», «río Amazonas») in South America is the largest river by discharge volume of water in the world, and the longest or second-longest river system in the world, a title which is disputed with the Nile.

The headwaters of the Apurímac River on Nevado Mismi had been considered, for nearly a century, the Amazon basin's most distant source until a 2014 study found it to be the headwaters of the Mantaro River on the Cordillera Rumi Cruz in Peru. The Mantaro and Apurímac rivers join, and with other tributaries form the Ucayali River, which in turn meets the Marañón River upstream of Iquitos, Peru, forming what countries other than Brazil consider to be the main stem of the Amazon. Brazilians call this section the Solimões River above its confluence with the Rio Negro forming what Brazilians call the Amazon at the Meeting of Waters («Encontro das Águas») at Manaus, the largest city on the river.

The Amazon River has an average discharge of about 215,000–—approximately 6,591– per year, greater than the next seven largest independent rivers combined. Two of the top ten rivers by discharge are tributaries of the Amazon river. The Amazon represents 20% of the global riverine discharge into oceans. The Amazon basin is the largest drainage basin in the world, with an area of approximately 7,000,000km2. The portion of the river's drainage basin in Brazil alone is larger than any other river's basin. The Amazon enters Brazil with only one-fifth of the flow it finally discharges into the Atlantic Ocean, yet already has a greater flow at this point than the discharge of any other river in the world. It has a recognized length of 6,400 km (4,000 miles) but according to some reports its length varies from 6,575–.

Etymology

The Amazon was initially known by Europeans as the Marañón, and the Peruvian part of the river is still known by that name, as well as the Brazilian state of Maranhão, which contains part of the Amazon. It later became known as Rio Amazonas in Spanish and Portuguese.
The name Rio Amazonas was reportedly given after native warriors attacked a 16th-century expedition by Francisco de Orellana. The warriors were led by women, reminding de Orellana of the Amazon warriors, a tribe of women warriors related to Iranian Scythians and Sarmatians mentioned in Greek mythology.

The word Amazon itself may be derived from the Iranian compound * ha-maz-an- "(one) fighting together" or ethnonym * ha-mazan- "warriors", a word attested indirectly through a derivation, a denominal verb in Hesychius of Alexandria's gloss «"ἁμαζακάραν· πολεμεῖν. Πέρσαι"» (": 'to make war' in Persian"), where it appears together with the Indo-Iranian root * kar- "make" (from which Sanskrit karma is also derived).

Other scholars claim that the name is derived from the Tupi word amassona, meaning "boat destroyer".

History

Timeline of Amazon history

Geological history

Geological studies suggest that for millions of years, the Amazon River flowed in the opposite direction – from east to west. Eventually the Andes Mountains formed, blocking its flow to the Pacific Ocean and causing it to switch directions to its current mouth in the Atlantic Ocean.

Pre-Columbian era

Old drawing (from 1879) of Arapaima fishing at the Amazon River. The arapaima has been on Earth for at least 23 million years.

During what many archaeologists called the formative stage, Amazonian societies were deeply involved in the emergence of South America's highland agrarian systems. The trade with Andean civilizations in the terrains of the headwaters in the Andes formed an essential contribution to the social and religious development of higher-altitude civilizations like the Muisca and Incas. Early human settlements were typically based on low-lying hills or mounds.

Shell mounds were the earliest evidence of habitation; they represent piles of human refuse and are mainly dated between 7500 BC and 4000 BC. They are associated with ceramic age cultures; no preceramic shell mounds have been documented so far by archaeologists. Artificial earth platforms for entire villages are the second type of mounds. They are best represented by the Marajoara culture. Figurative mounds are the most recent types of occupation.

There is ample evidence that the areas surrounding the Amazon River were home to complex and large-scale indigenous societies, mainly chiefdoms who developed towns and cities. Archaeologists estimate that by the time the Spanish conquistador De Orellana traveled across the Amazon in 1541, more than 3 million indigenous people lived around the Amazon. These pre-Columbian settlements created highly developed civilizations. For instance, pre-Columbian indigenous people on the island of Marajó may have developed social stratification and supported a population of 100,000 people. To achieve this level of development, the indigenous inhabitants of the Amazon rainforest altered the forest's ecology by selective cultivation and the use of fire. Scientists argue that by burning areas of the forest repeatedly, the indigenous people caused the soil to become richer in nutrients. This created dark soil areas known as terra preta de índio ("Indian dark earth"). Because of the terra preta, indigenous communities were able to make land fertile and thus sustainable for the large-scale agriculture needed to support their large populations and complex social structures. Further research has hypothesized that this practice began around 11,000 years ago. Some say that its effects on forest ecology and regional climate explain the otherwise inexplicable band of lower rainfall through the Amazon basin.

Many indigenous tribes engaged in constant warfare. According to James S. Olson, "The Munduruku expansion (in the 18th century) dislocated and displaced the Kawahíb, breaking the tribe down into much smaller groups ... Munduruku first came to the attention of Europeans in 1770 when they began a series of widespread attacks on Brazilian settlements along the Amazon River."

Arrival of Europeans

Amazon tributaries near Manaus

In March 1500, Spanish conquistador Vicente Yáñez Pinzón was the first documented European to sail up the Amazon River. Pinzón called the stream Río Santa María del Mar Dulce, later shortened to Mar Dulce, literally, sweet sea, because of its freshwater pushing out into the ocean. Another Spanish explorer, Francisco de Orellana, was the first European to travel from the origins of the upstream river basins, situated in the Andes, to the mouth of the river. In this journey, Orellana baptized some of the affluents of the Amazonas like Rio Negro, Napo and Jurua.

The name Amazonas is thought to be taken from the native warriors that attacked this expedition, mostly women, that reminded De Orellana of the mythical female Amazon warriors from the ancient Hellenic culture in Greece (see also Origin of the name).

Exploration

Samuel Fritz's 1707 map showing the Amazon and the Orinoco

Gonzalo Pizarro set off in 1541 to explore east of Quito into the South American interior in search of El Dorado, the "city of gold" and La Canela, the "valley of cinnamon". He was accompanied by his second-in-command Francisco de Orellana. After 170.km, the Coca River joined the Napo River (at a point now known as Puerto Francisco de Orellana); the party stopped for a few weeks to build a boat just upriver from this confluence. They continued downriver through an uninhabited area, where they could not find food. Orellana offered and was ordered to follow the Napo River, then known as Río de la Canela ("Cinnamon River"), and return with food for the party. Based on intelligence received from a captive native chief named Delicola, they expected to find food within a few days downriver by ascending another river to the north.

De Orellana took about 57 men, the boat, and some canoes and left Pizarro's troops on 26 December 1541. However, De Orellana missed the confluence (probably with the Aguarico) where he was searching supplies for his men. By the time he and his men reached another village, many of them were sick from hunger and eating "noxious plants", and near death. Seven men died in that village. His men threatened to mutiny if the expedition turned back to attempt to rejoin Pizarro, the party being over 100 leagues downstream at this point. He accepted to change the purpose of the expedition to discover new lands in the name of the king of Spain, and the men built a larger boat in which to navigate downstream. After a journey of 600km down the Napo River, they reached a further major confluence, at a point near modern Iquitos, and then followed the upper Amazon, now known as the Solimões, for a further 1200.km to its confluence with the Rio Negro (near modern Manaus), which they reached on 3 June 1542.

Regarding the initial mission of finding cinnamon, Pizarro reported to the king that they had found cinnamon trees, but that they could not be profitably harvested. True cinnamon (Cinnamomum Verum) is not native to South America. Other related cinnamon-containing plants (of the family Lauraceae) are fairly common in that part of the Amazon and Pizarro probably saw some of these. The expedition reached the mouth of the Amazon on 24 August 1542, demonstrating the practical navigability of the Great River.

Masked-dance, and wedding-feast of Ticuna Indians, engravings for Bates's 1863 The Naturalist on the River Amazons

In 1560, another Spanish conquistador, Lope de Aguirre, may have made the second descent of the Amazon. Historians are uncertain whether the river he descended was the Amazon or the Orinoco River, which runs more or less parallel to the Amazon further north.

Portuguese explorer Pedro Teixeira was the first European to travel up the entire river. He arrived in Quito in 1637, and returned via the same route.

From 1648 to 1652, Portuguese Brazilian bandeirante António Raposo Tavares led an expedition from São Paulo overland to the mouth of the Amazon, investigating many of its tributaries, including the Rio Negro, and covering a distance of over 10000km.

In what is currently in Brazil, Ecuador, Bolivia, Colombia, Peru, and Venezuela, several colonial and religious settlements were established along the banks of primary rivers and tributaries for trade, slaving , and evangelization among the indigenous peoples of the vast rainforest, such as the Urarina. In the late 1600s, Czech Jesuit Father Samuel Fritz, an apostle of the Omagus established some forty mission villages. Fritz proposed that the Marañón River must be the source of the Amazon, noting on his 1707 map that the Marañón "has its source on the southern shore of a lake that is called Lauricocha, near Huánuco." Fritz reasoned that the Marañón is the largest river branch one encounters when journeying upstream, and lies farther to the west than any other tributary of the Amazon. For most of the 18th–19th centuries and into the 20th century, the Marañón was generally considered the source of the Amazon.

Henry Walter Bates was most famous for his expedition to the Amazon (1848–1859).

Scientific exploration

Early scientific, zoological, and botanical exploration of the Amazon River and basin took place from the 18th century through the first half of the 19th century.


Post-colonial exploitation and settlement

Amazonas state

Metropolitan Cathedral of Santarém, in Santarém, Brazil
Amazon Theatre opera house in Manaus built in 1896 during the rubber boom

Iglesia Matriz in Iquitos, Peru

The Cabanagem revolt (1835–1840) was directed against the white ruling class. It is estimated that from 30% to 40% of the population of Grão-Pará, estimated at 100,000 people, died.

The population of the Brazilian portion of the Amazon basin in 1850 was perhaps 300,000, of whom about 175,000 were Europeans and 25,000 were slaves. The Brazilian Amazon's principal commercial city, Pará (now Belém), had from 10,000 to 12,000 inhabitants, including slaves. The town of Manáos, now Manaus, at the mouth of the Rio Negro, had a population between 1,000 and 1,500. All the remaining villages, as far up as Tabatinga, on the Brazilian frontier of Peru, were relatively small.

On 6 September 1850, Emperor Pedro II of Brazil sanctioned a law authorizing steam navigation on the Amazon and gave the Viscount of Mauá (Irineu Evangelista de Sousa) the task of putting it into effect. He organised the "Companhia de Navegação e Comércio do Amazonas" in Rio de Janeiro in 1852; in the following year it commenced operations with four small steamers, the Monarca ('Monarch'), the Cametá, the Marajó and the Rio Negro.

At first, navigation was principally confined to the main river; and even in 1857 a modification of the government contract only obliged the company to a monthly service between Pará and Manaus, with steamers of 200 tons cargo capacity, a second line to make six round voyages a year between Manaus and Tabatinga, and a third, two trips a month between Pará and Cametá. This was the first step in opening up the vast interior.

The success of the venture called attention to the opportunities for economic exploitation of the Amazon, and a second company soon opened commerce on the Madeira, Purús, and Negro; a third established a line between Pará and Manaus, and a fourth found it profitable to navigate some of the smaller streams. In that same period, the Amazonas Company was increasing its fleet. Meanwhile, private individuals were building and running small steam craft of their own on the main river as well as on many of its tributaries.

On 31 July 1867, the government of Brazil, constantly pressed by the maritime powers and by the countries encircling the upper Amazon basin, especially Peru, decreed the opening of the Amazon to all countries, but they limited this to certain defined points: Tabatinga – on the Amazon; Cametá – on the Tocantins; Santarém – on the Tapajós; Borba – on the Madeira, and Manaus – on the Rio Negro. The Brazilian decree took effect on 7 September 1867.

Thanks in part to the mercantile development associated with steamboat navigation coupled with the internationally driven demand for natural rubber, the Peruvian city of Iquitos became a thriving, cosmopolitan center of commerce. Foreign companies settled in Iquitos, from where they controlled the extraction of rubber. In 1851 Iquitos had a population of 200, and by 1900 its population reached 20,000. In the 1860s, approximately 3,000 tons of rubber were being exported annually, and by 1911 annual exports had grown to 44,000 tons, representing 9.3% of Peru's exports. During the rubber boom it is estimated that diseases brought by immigrants, such as typhus and malaria, killed 40,000 native Amazonians.

The first direct foreign trade with Manaus commenced around 1874. Local trade along the river was carried on by the English successors to the Amazonas Company—the Amazon Steam Navigation Company—as well as numerous small steamboats, belonging to companies and firms engaged in the rubber trade, navigating the Negro, Madeira, Purús, and many other tributaries, such as the Marañón, to ports as distant as Nauta, Peru.

By the turn of the 20th century, the exports of the Amazon basin were India-rubber, cacao beans, Brazil nuts and a few other products of minor importance, such as pelts and exotic forest produce (resins, barks, woven hammocks, prized bird feathers, live animals) and extracted goods, such as lumber and gold.

20th-century development

Manaus, the largest city in Amazonas, as seen from a NASA satellite image, surrounded by the dark Rio Negro and the muddy Amazon River

City of Manaus

Floating houses in Leticia, Colombia

Since colonial times, the Portuguese portion of the Amazon basin has remained a land largely undeveloped by agriculture and occupied by indigenous people who survived the arrival of European diseases.

Four centuries after the European discovery of the Amazon river, the total cultivated area in its basin was probably less than 65km2, excluding the limited and crudely cultivated areas among the mountains at its extreme headwaters. This situation changed dramatically during the 20th century.

Wary of foreign exploitation of the nation's resources, Brazilian governments in the 1940s set out to develop the interior, away from the seaboard where foreigners owned large tracts of land. The original architect of this expansion was president Getúlio Vargas, with the demand for rubber from the Allied forces in World War II providing funding for the drive.

In the 1960s, economic exploitation of the Amazon basin was seen as a way to fuel the "economic miracle" occurring at the time. This resulted in the development of "Operation Amazon", an economic development project that brought large-scale agriculture and ranching to Amazonia. This was done through a combination of credit and fiscal incentives.

However, in the 1970s the government took a new approach with the National Integration Program (PIN). A large-scale colonization program saw families from northeastern Brazil relocated to the "land without people" in the Amazon Basin. This was done in conjunction with infrastructure projects mainly the Trans-Amazonian Highway (Transamazônica).

The Trans-Amazonian Highway's three pioneering highways were completed within ten years but never fulfilled their promise. Large portions of the Trans-Amazonian and its accessory roads, such as BR-317 (Manaus-Porto Velho), are derelict and impassable in the rainy season. Small towns and villages are scattered across the forest, and because its vegetation is so dense, some remote areas are still unexplored.

Many settlements grew along the road from Brasília to Belém with the highway and National Integration Program, however, the program failed as the settlers were unequipped to live in the delicate rainforest ecosystem. This, although the government believed it could sustain millions, instead could sustain very few.

With a population of 1.9 million people in 2014, Manaus is the largest city on the Amazon. Manaus alone makes up approximately 50% of the population of the largest Brazilian state of Amazonas. The racial makeup of the city is 64% pardo (mulatto and mestizo) and 32% white.

Although the Amazon river remains undammed, around 412 dams are in operation on the Amazon's tributary rivers. Of these 412 dams, 151 are constructed over six of the main tributary rivers that drain into the Amazon. Since only 4% of the Amazon's hydropower potential has been developed in countries like Brazil, more damming projects are underway and hundreds more are planned. After witnessing the negative effects of environmental degradation, sedimentation, navigation and flood control caused by the Three Gorges Dam in the Yangtze River, scientists are worried that constructing more dams in the Amazon will harm its biodiversity in the same way by "blocking fish-spawning runs, reducing the flows of vital oil nutrients and clearing forests". Damming the Amazon River could potentially bring about the "end of free flowing rivers" and contribute to an "ecosystem collapse" that will cause major social and environmental problems.

Course

Origins

Source of the Amazon River

The Amazon was thought to originate from the Apacheta cliff in Arequipa at the Nevado Mismi, marked only by a wooden cross.

Nevado Mismi, formerly considered to be the source of the Amazon

Marañón River in Peru

The most distant source of the Amazon was thought to be in the Apurímac river drainage for nearly a century. Such studies continued to be published even as recently as 1996, 2001, 2007, and 2008, where various authors identified the snowcapped 5597m Nevado Mismi peak, located roughly 160km west of Lake Titicaca and 700km southeast of Lima, as the most distant source of the river. From that point, Quebrada Carhuasanta emerges from Nevado Mismi, joins Quebrada Apacheta and soon forms Río Lloqueta which becomes Río Hornillos and eventually joins the Río Apurímac.

A 2014 study by Americans James Contos and Nicolas Tripcevich in Area, a peer-reviewed journal of the Royal Geographical Society, however, identifies the most distant source of the Amazon as actually being in the Río Mantaro drainage. A variety of methods were used to compare the lengths of the Mantaro river vs. the Apurímac river from their most distant source points to their confluence, showing the longer length of the Mantaro. Then distances from Lago Junín to several potential source points in the uppermost Mantaro river were measured, which enabled them to determine that the Cordillera Rumi Cruz was the most distant source of water in the Mantaro basin (and therefore in the entire Amazon basin). The most accurate measurement method was direct GPS measurement obtained by kayak descent of each of the rivers from their source points to their confluence (performed by Contos). Obtaining these measurements was difficult given the class IV–V nature of each of these rivers, especially in their lower "Abyss" sections. Ultimately, they determined that the most distant point in the Mantaro drainage is nearly 80 km farther upstream compared to Mt. Mismi in the Apurímac drainage, and thus the maximal length of the Amazon river is about 80 km longer than previously thought. Contos continued downstream to the ocean and finished the first complete descent of the Amazon from its newly identified source (finishing November 2012), a journey repeated by two groups after the news spread.

After about 700km, the Apurímac then joins Río Mantaro to form the Ene, which joins the Perene to form the Tambo, which joins the Urubamba River to form the Ucayali. After the confluence of Apurímac and Ucayali, the river leaves Andean terrain and is surrounded by floodplain. From this point to the confluence of the Ucayali and the Marañón, some 1600km, the forested banks are just above the water and are inundated long before the river attains its maximum flood stage. The low river banks are interrupted by only a few hills, and the river enters the enormous Amazon rainforest.

The Upper Amazon or Solimões

Amazon River near Iquitos, Peru

Although the Ucayali–Marañón confluence is the point at which most geographers place the beginning of the Amazon River proper, in Brazil the river is known at this point as the Solimões das Águas. The river systems and flood plains in Brazil, Peru, Ecuador, Colombia, and Venezuela, whose waters drain into the Solimões and its tributaries, are called the "Upper Amazon".

The Amazon proper runs mostly through Brazil and Peru, and is part of the border between Colombia and Peru. It has a series of major tributaries in Colombia, Ecuador and Peru, some of which flow into the Marañón and Ucayali, and others directly into the Amazon proper. These include rivers Putumayo, Caquetá, Vaupés, Guainía, Morona, Pastaza, Nucuray, Urituyacu, Chambira, Tigre, Nanay, Napo, and Huallaga.

At some points, the river divides into anabranches, or multiple channels, often very long, with inland and lateral channels, all connected by a complicated system of natural canals, cutting the low, flat igapó lands, which are never more than 5m above low river, into many islands.

From the town of Canaria at the great bend of the Amazon to the Negro, vast areas of land are submerged at high water, above which only the upper part of the trees of the sombre forests appear. Near the mouth of the Rio Negro to Serpa, nearly opposite the river Madeira, the banks of the Amazon are low, until approaching Manaus, they rise to become rolling hills.

The Lower Amazon

Meeting of Waters; the confluence of Rio Negro (blue) and Rio Solimões (sandy) near Manaus, Brazil

Water samples of the Solimões (right) and Rio Negro (left)

The Lower Amazon begins where the darkly colored waters of the Rio Negro meets the sandy-colored Rio Solimões (the upper Amazon), and for over 6km these waters run side by side without mixing. At Óbidos, a bluff 17m above the river is backed by low hills. The lower Amazon seems to have once been a gulf of the Atlantic Ocean, the waters of which washed the cliffs near Óbidos.

Only about 10% of the Amazon's water enters downstream of Óbidos, very little of which is from the northern slope of the valley. The drainage area of the Amazon basin above Óbidos city is about 5000000km2, and, below, only about 1000000km2 (around 20%), exclusive of the 1400000km2 of the Tocantins basin. The Tocantins River enters the southern portion of the Amazon delta.

In the lower reaches of the river, the north bank consists of a series of steep, table-topped hills extending for about 240km from opposite the mouth of the Xingu as far as Monte Alegre. These hills are cut down to a kind of terrace which lies between them and the river.

On the south bank, above the Xingu, a line of low bluffs bordering the floodplain extends nearly to Santarém in a series of gentle curves before they bend to the southwest, and, abutting upon the lower Tapajós, merge into the bluffs which form the terrace margin of the Tapajós river valley.

Mouth

Satellite image of the mouth of the Amazon River, from the north looking south

Belém is the major city and port at the mouth of the river at the Atlantic Ocean. The definition of where exactly the mouth of the Amazon is located, and how wide it is, is a matter of dispute, because of the area's peculiar geography. The Pará and the Amazon are connected by a series of river channels called furos near the town of Breves; between them lies Marajó, the world's largest combined river/sea island.

If the Pará river and the Marajó island ocean frontage are included, the Amazon estuary is some 325km wide. In this case, the width of the mouth of the river is usually measured from Cabo Norte, the cape located straight east of Pracuúba in the Brazilian state of Amapá, to Ponta da Tijoca near the town of Curuçá, in the state of Pará.

A more conservative measurement excluding the Pará river estuary, from the mouth of the Araguari River to Ponta do Navio on the northern coast of Marajó, would still give the mouth of the Amazon a width of over 180.km. If only the river's main channel is considered, between the islands of Curuá (state of Amapá) and Jurupari (state of Pará), the width falls to about 15km.

The plume generated by the river's discharge covers up to 1.3 million km2 and is responsible for muddy bottoms influencing a wide area of the tropical north Atlantic in terms of salinity, pH, light penetration, and sedimentation.

Lack of bridges

There are no bridges across the entire width of the river. This is not because the river would be too wide to bridge; for most of its length, engineers could build a bridge across the river easily. For most of its course, the river flows through the Amazon Rainforest, where there are very few roads and cities. Most of the time, the crossing can be done by a ferry. The Manaus Iranduba Bridge linking the cities of Manaus and Iranduba spans the Rio Negro, the second-largest tributary of the Amazon, just before their confluence.

Dispute regarding length

River taxi in Peru

Coastline paradox
While debate as to whether the Amazon or the Nile is the world's longest river has gone on for many years, the historic consensus of geographic authorities has been to regard the Amazon as the second longest river in the world, with the Nile being the longest. However, the Amazon has been reported as being anywhere between 6275km and 6992km long. It is often said to be "at least" 6400km long. The Nile is reported to be anywhere from 5499to. Often it is said to be "about" 6650km long. There are several factors that can affect these measurements, such as the position of the geographical source and the mouth, the scale of measurement, and the length measuring techniques (for details see also List of rivers by length).

In July 2008, the Brazilian Institute for Space Research (INPE) published a news article on their webpage, claiming that the Amazon River was 140km longer than the Nile. The Amazon's length was calculated as 6992km, taking the Apacheta Creek as its source. Using the same techniques, the length of the Nile was calculated as 6853km, which is longer than previous estimates but still shorter than the Amazon. The results were reached by measuring the Amazon downstream to the beginning of the tidal estuary of Canal do Sul and then, after a sharp turn back, following tidal canals surrounding the isle of Marajó and finally including the marine waters of the Río Pará bay in its entire length. According to an earlier article on the webpage of the National Geographic, the Amazon's length was calculated as 6800km by a Brazilian scientist. In June 2007, Guido Gelli, director of science at the Brazilian Institute of Geography and Statistics (IBGE), told London's Telegraph Newspaper that it could be considered that the Amazon was the longest river in the world. However, according to the above sources, none of the two results was published, and questions were raised about the researchers' methodology. In 2009, a peer-reviewed article, was published, concluding that the Nile is longer than the Amazon by stating a length of 7088km for the Nile and 6575km for the Amazon, measured by using a combination of satellite image analysis and field investigations to the source regions.

According to the Encyclopædia Britannica, the final length of the Amazon remains open to interpretation and continued debate.

Watershed

Amazon basin
The Amazon basin, the largest in the world, covers about 40% of South America, an area of approximately 7,050,000km2. It drains from west to east, from Iquitos in Peru, across Brazil to the Atlantic. It gathers its waters from 5 degrees north latitude to 20 degrees south latitude. Its most remote sources are found on the inter-Andean plateau, just a short distance from the Pacific Ocean.

The Amazon River and its tributaries are characterised by extensive forested areas that become flooded every rainy season. Every year, the river rises more than 9m, flooding the surrounding forests, known as várzea ("flooded forests"). The Amazon's flooded forests are the most extensive example of this habitat type in the world. In an average dry season, 110000km2 of land are water-covered, while in the wet season, the flooded area of the Amazon basin rises to 350000km2.

The quantity of water released by the Amazon to the Atlantic Ocean is enormous: up to 300000m3/s in the rainy season, with an average of 209000m3/s from 1973 to 1990. The Amazon is responsible for about 20% of the Earth's fresh water entering the ocean. The river pushes a vast plume of fresh water into the ocean. The plume is about 400km long and between 100and wide. The fresh water, being lighter, flows on top of the seawater, diluting the salinity and altering the colour of the ocean surface over an area up to 2500000km2 in extent. For centuries ships have reported fresh water near the Amazon's mouth yet well out of sight of land in what otherwise seemed to be the open ocean.

Despite this, the Atlantic has sufficient wave and tidal energy to carry most of the Amazon's sediments out to sea, thus the Amazon does not form a significant river delta. The great deltas of the world are all in relatively protected bodies of water, while the Amazon empties directly into the turbulent Atlantic.

There is a natural water union between the Amazon and the Orinoco basins, the so-called Casiquiare canal. The Casiquiare is a river distributary of the upper Orinoco, which flows southward into the Rio Negro, which in turn flows into the Amazon. The Casiquiare is the largest river on earth that links two major river systems, a so-called bifurcation.

Discharge

Average discharge at the estuary; Period from 2003 to 2015: 7,200km3/year

Year(km3)(m3/s)Year(km3)(m3/s)
20036,470205,00020106,464205,000
20046,747214,00020117,378234,000
20056,522207,00020127,513238,000
20067,829248,00020137,288231,000
20077,133226,00020147,674243,000
20087,725245,00020156,657211,000
20098,200260,000

[[Amazon Delta]]

Water discharge of the Amazon with Tocantins River. Complete series from starting 1920.

YearDischargeYearDischarge
2015210.91967231
2014243.21966237
2013230.91965232
2012238.11964218
2011233.81963240
2010204.81962220
20092601961229
2008244.81960207
20072261959236
2006248.11958229
2005206.71957210
2004213.81956230
20032051955233
20022141954238
20012161953234
20002341952223
19992121951227
19981491950230
19972011949213
19962121948228
19951951947210
19942401946222
19932181945192
19921561944220
19912181943208
19901981942200
19892301941203
19882001940208
19871801939229
19862081938200
19852401937188
19842701936183
19831861935215
19822361934230
19812021933200
19801901932214
19792241931190
19782331930209
19772321929201
19762391928208
19752421927220
19742421926202
19732241925210
19722381924222
19712351923210
19702201922219
19692111921224
19682101920200
Source:

AmazonPará
January126,1007,300
February177,10014,200
March186,30018,200
April201,30028,700
May236,60038,700
June275,60040,500
July296,90032,600
August288,50014,500
September262,5006,100
October227,0002,500
November118,8001,000
December82,4001,000
Average206,60017,100
Source:

Santarém

Water discharge of the Amazon River at the Santarém gauging station.

MinMeanMax
199869,202175,218278,306
199973,921182,266270,080
200073,306171,899275,060
200167,300173,517268,820
200292,711207,186296,805
2003100,473182,767252,626
2004100,986184,880265,644
200567,464172,411280,340
200691,126192,500301,860
200773,256192,715309,478
2008101,146198,128316,669
200976,598204,920303,192
201072,101172,255255,208
201165,803155,030256,798
201250,070194,883323,680
201355,108206,295305,526
2014151,997235,390338,905
201570,119261,580378,767
201669,995230,788367,296
2017104,111223,193352,935
201895,376262,946386,022
201996,260260,664382,840
202072,955234,725388,213
202194,903262,264376,740
2022101,693259,902405,999
202346,130217,551370,109
202448,898198,627350,570
Source: The Flood Observatory

Óbidos

Water discharge of the Amazon River at the Óbidos gauging station. Complete series from starting 1903.

YearMinMeanMaxYearMinMeanMax
202361,000154,988333,700196292,800167,864245,100
202277,200162,990375,200196177,800153,577221,400
2021106,700177,000353,800196099,300161,502230,300
202092,800170,912344,8001959103,000159,604231,900
201987,900162,810352,300195873,700153,243234,300
201892,300180,232336,200195784,200156,814227,200
201793,300181,025352,1001956123,700160,720236,100
201687,600159,308347,500195580,100166,970252,700
2015120,400186,731355,300195494,400173,000253,300
2014113,000196,940321,700195390,600189,070394,000
2013117,400193,573301,200195294,100158,150317,000
201287,900192,292370,0001951101,900161,110283,000
201180,600176,523242,800195078,200166,078368,000
201077,100165,902254,0001949116,700171,323356,000
200985,800198,590291,040194878,400159,946288,000
200887,700193,072280,8001947109,200165,500213,000
200795,500174,068278,600194693,700172,012283,000
200688,400184,690279,200194588,200148,566244,000
200572,800161,830273,500194496,800174,608309,000
200486,400165,096218,500194388,200161,866260,000
200390,400170,802248,000194293,200154,500236,000
200293,700177,493265,400194186,800156,379231,000
200174,400175,527257,0001940119,000157,708213,000
200087,900181,146258,5001939126,000174,625281,000
199975,300185,737299,700193894,000154,412257,000
199875,000149,382268,200193782,800143,237212,000
199772,400169,129265,800193681,900139,133212,000
1996108,600180,190251,200193582,500169,612299,000
199574,600151,499259,3001934129,000173,166292,000
1994106,000200,335296,000193383,600154,658256,000
1993106,000181,290262,000193293,400165,096260,000
199291,800138,555194,600193188,500146,354230,000
199182,500169,444248,000193098,400158,679243,000
199083,400167,368235,000192986,600156,037276,000
1989120,000206,941346,000192892,600151,000284,000
198892,300165,547228,0001927119,600159,940231,900
198792,200164,552231,000192670,700111,513151,400
1986125,000182,247244,000192596,000171,547250,800
1985113,000159,840190,000192495,500142,416202,900
1984105,000173,350259,000192391,500178,802246,300
198386,100140,892179,0001922129,000187,619279,200
198296,100186,200302,000192193,000174,784268,900
198188,300149,806191,0001920116,900175,452255,200
198091,200142,473176,000191988,700148,443209,000
197991,500169,696267,0001918103,000170,543260,200
1978115,300178,293257,000191794,400136,835215,600
1977119,700176,834269,000191670,100144,984213,800
197695,400192,734327,000191586,700159,604235,700
1975106,000197,545307,000191494,600171,882253,600
1974131,600193,870280,0001913131,000178,132252,700
1973123,000179,537250,0001912112,500135,047185,700
1972109,000182,624264,000191183,200159,710232,100
1971121,400187,121288,0001910102,000154,024237,100
197084,500163,232239,000190976,400170,095274,800
196989,200156,720210,0001908102,100176,793267,700
1968113,000148,220202,000190784,600140,184224,800
196789,000162,506227,000190669,600142,194202,200
196687,300143,868207,400190593,500141,524203,900
196585,400144,650215,600190493,300174,561262,500
1964103,500136,612202,300190382,800148,220230,000
196372,800141,190226,800
Source:

MonthDischarge (m3/s)
January137,749
February163,264
March186,036
April206,989
May220,717
June221,055
July209,765
August186,655
September149,159
October112,032
November102,544
December114,746
Source:

Itacoatiara

Water discharge of the Amazon River at the Itacoatiara gauging station.

MinMeanMax
199841,312139,002240,396
199964,130171,662288,869
200052,870161,345261,176
200130,670157,286256,627
200267,979164,171252,425
200382,556149,274228,998
200466,183139,926223,929
200557,598145,002258,383
200661,265168,975268,108
200774,679161,393238,839
200871,572168,065259,841
200959,298166,100275,544
201053,715128,035215,638
201142,192129,710230,293
201229,489172,103291,537
201351,341172,201286,872
201485,599192,462324,191
201566,094221,843339,832
201641,063167,746311,494
201760,218205,382329,771
201865,629202,838316,291
201996,549227,078340,215
202044,698214,586352,671
202185,862236,885354,795
202256,758214,763337,412
202338,496173,676304,336
202427,088156,907297,641
Source: The Flood Observatory

MonthDischarge (m3/s)
January122,910
February146,170
March170,972
April185,403
May198,166
June200,022
July190,811
August170,101
September133,948
October99,706
November93,029
December103,054
Source:

Sediment load

Sediment load (S - 754 x 106 ton/year) at Óbidos gauge station (period from 1996 to 2007).

YearSYearS
19966722002802
19976912003832
19986522004807
19997322005797
20006922006742
20017872007842
Source:

Flooding

NASA satellite image of a flooded portion of the river

Not all of the Amazon's tributaries flood at the same time of the year. Many branches begin flooding in November and might continue to rise until June. The rise of the Rio Negro starts in February or March and begins to recede in June. The Madeira River rises and falls two months earlier than most of the rest of the Amazon river.

The depth of the Amazon between Manacapuru and Óbidos has been calculated as between 20and. At Manacapuru, the Amazon's water level is only about 24m above mean sea level. More than half of the water in the Amazon downstream of Manacapuru is below sea level. In its lowermost section, the Amazon's depth averages 20to, in some places as much as 100m.

The main river is navigable for large ocean steamers to Manaus, 1500km upriver from the mouth. Smaller ocean vessels below 9000 tons and with less than 5.5m draft can reach as far as Iquitos, Peru, 3600km from the sea. Smaller riverboats can reach 780km higher, as far as Achual Point. Beyond that, small boats frequently ascend to the Pongo de Manseriche, just above Achual Point in Peru.

Annual flooding occurs in late northern latitude winter at high tide when the incoming waters of the Atlantic are funnelled into the Amazon delta. The resulting undular tidal bore is called the pororoca, with a leading wave that can be up to 25ft high and travel up to 500mi inland.

Geology

The Amazon River originated as a transcontinental river in the Miocene epoch between 11.8 million and 11.3 million years ago and took its present shape approximately 2.4 million years ago in the Early Pleistocene.

The proto-Amazon during the Cretaceous flowed west, as part of a proto-Amazon-Congo river system, from the interior of present-day Africa when the continents were connected, forming western Gondwana. 80 million years ago, the two continents split. Fifteen million years ago, the main tectonic uplift phase of the Andean chain started. This tectonic movement is caused by the subduction of the Nazca Plate underneath the South American Plate. The rise of the Andes and the linkage of the Brazilian and Guyana bedrock shields, blocked the river and caused the Amazon Basin to become a vast inland sea. Gradually, this inland sea became a massive swampy, freshwater lake and the marine inhabitants adapted to life in freshwater.

Eleven to ten million years ago, waters worked through the sandstone from the west and the Amazon began to flow eastward, leading to the emergence of the Amazon rainforest. During glacial periods, sea levels dropped and the great Amazon lake rapidly drained and became a river, which would eventually become the disputed world's longest, draining the most extensive area of rainforest on the planet.

Paralleling the Amazon River is a large aquifer, dubbed the Hamza River, the discovery of which was made public in August 2011.

Protected areas

NameCountryCoordinatesImageNotes
Allpahuayo-Mishana National ReservePeru3°56′S, 73°33′W
150px
Amacayacu National ParkColombia3°29′S, 72°12′W
150px
Amazônia National ParkBrazil4°26′S, 56°50′W
150px
Anavilhanas National ParkBrazil2°23′S, 60°55′W
150px

Flora and fauna

Biodiversity of Colombia#Amazon natural region

Flora

Fauna

The tambaqui, an important species in Amazonian fisheries, breeds in the Amazon River.

:Category:Fauna of the Amazon
More than one-third of all known species in the world live in the Amazon rainforest. It is the richest tropical forest in the world in terms of biodiversity. In addition to thousands of species of fish, the river supports crabs, algae, and turtles.

Mammals

Amazon river dolphin

Along with the Orinoco, the Amazon is one of the main habitats of the boto, also known as the Amazon river dolphin (Inia geoffrensis). It is the largest species of river dolphin, and it can grow to lengths of up to 2.6m. The colour of its skin changes with age; young animals are gray, but become pink and then white as they mature. The dolphins use echolocation to navigate and hunt in the river's tricky depths. The boto is the subject of a legend in Brazil about a dolphin that turns into a man and seduces maidens by the riverside.

The tucuxi (Sotalia fluviatilis), also a dolphin species, is found both in the rivers of the Amazon basin and in the coastal waters of South America. The Amazonian manatee (Trichechus inunguis), also known as "seacow", is found in the northern Amazon River basin and its tributaries. It is a mammal and a herbivore. Its population is limited to freshwater habitats, and, unlike other manatees, it does not venture into saltwater. It is classified as vulnerable by the International Union for Conservation of Nature.

The Amazon and its tributaries are the main habitat of the giant otter (Pteronura brasiliensis). Sometimes known as the "river wolf," it is one of South America's top carnivores. Because of habitat destruction and hunting, its population has dramatically decreased. It is now listed on Appendix I of the Convention on International Trade in Endangered Species (CITES), which effectively bans international trade.

Reptiles

The green anaconda is the heaviest and one of the longest known extant snake species.

The anaconda is found in shallow waters in the Amazon basin. One of the world's largest species of snake, the anaconda spends most of its time in the water with just its nostrils above the surface. Species of caimans, that are related to alligators and other crocodilians, also inhabit the Amazon as do varieties of turtles.

Birds

Fish

Characins, such as the piranha species, are prey for the giant otter, but these aggressive fish may also pose a danger to humans.

The neon tetra is one of the most popular aquarium fish.

The Amazonian fish fauna is the centre of diversity for neotropical fishes, some of which are popular aquarium specimens like the neon tetra and the freshwater angelfish. More than 5,600 species were known As of 2011, and approximately fifty new species are discovered each year. The arapaima, known in Brazil as the pirarucu, is a South American tropical freshwater fish, one of the largest freshwater fish in the world, with a length of up to 15ft. Another Amazonian freshwater fish is the arowana (or aruanã in Portuguese), such as the silver arowana (Osteoglossum bicirrhosum), which is a predator and very similar to the arapaima, but only reaches a length of 120cm. Also present in large numbers is the notorious piranha, an omnivorous fish that congregates in large schools and may attack livestock. There are approximately 30 to 60 species of piranha. The candirú, native to the Amazon River, is a species of parasitic fresh water catfish in the family Trichomycteridae, just one of more than 1200 species of catfish in the Amazon basin. Other catfish 'walk' overland on their ventral fins, while the kumakuma (Brachyplatystoma filamentosum), aka piraiba or "goliath catfish", can reach 3.6m in length and 200kg in weight.

The electric eel (Electrophorus electricus) and more than 100 species of electric fishes (Gymnotiformes) inhabit the Amazon basin. River stingrays (Potamotrygonidae) are also known. The bull shark (Carcharhinus leucas), a euryhaline species which can thrive in both salt and fresh water, has been reported as far as 4000km up the Amazon River at Iquitos in Peru.

Butterflies

List of butterflies of the Amazon River basin and the Andes

Microbiota

Freshwater microbes are generally not very well known, even less so for a pristine ecosystem like the Amazon. Recently, metagenomics has provided answers to what kind of microbes inhabit the river. The most important microbes in the Amazon River are Actinomycetota, Alphaproteobacteria, Betaproteobacteria, Gammaproteobacteria and Thermoproteota.

Challenges

The Amazon River serves as a vital lifeline for more than 47 million people in its basin and faces a multitude of challenges that threaten both its ecosystem and the indigenous communities dependent on its resources. According to the Office of the United Nations High Commissioner for Human Rights (OHCHR), the Yanomami, a tribe of approximately 30,000, struggles to preserve their land, culture, and traditional way of life due to encroaching illegal gold miners, malnutrition, and malaria. Meanwhile, in 2022, the region's severe drought, has led to a devastating increase in water temperatures, reaching 39.1 degrees Celsius, causing the demise of 125 Amazon river dolphins. This event displays the deteriorating environmental conditions and indicates the increasing vulnerability of the river's ecosystem. In recent years, the Amazon River has experienced historically low water levels, the lowest in over a century. Brazil, the primary custodian of this invaluable natural resource, grapples with the challenges of mitigating the effects of this drought on communities and ecosystems, further emphasizing the urgency of sustainable environmental management and conservation efforts.

Major tributaries

Solimões, the section of the upper Amazon River

Aerial view of an Amazon tributary

The Amazon has over 1,100 tributaries, twelve of which are over 1500km long. Some of the more notable ones are:

List of major tributaries

The main river and tributaries are (sorted in order from the confluence of Ucayali and Marañón rivers to the mouth):

Left tributaryRight tributaryLength (km)Basin size (km2)Average discharge (m3/s)
Upper Amazon (Confluence of Ucayali and Marañón rivers - Tabatinga)
Marañón2,112364,873.416,708
Ucayali2,738353,729.313,630.1
Tahuyo801,630105.7
Tamshiyaçu86.71,367.386.5
Itaya2132,668161.4
Nanay48316,673.41,072.7
Maniti198.72,573.6180.4
Napo1,075103,307.87,147.8
Apayaçu502,393.6160.9
Orosa953,506.8234.3
Ampiyaçu1404,201.4267.2
Chichita481,314.287.7
Cochiquinas492,362.7150.2
Santa Rosa451,678101.5
Cajocumal582,094.9141.5
Atacuari1083,480.5236.8
Middle Amazon (Tabatinga - Encontro das Águas)
Javary1,05699,674.15,222.5
Igarapé Veneza943.958.3
Tacana54135.5
Igarapé de Belém1,299.985.4
Igarapé São Jerônimo1,259.678.2
Jandiatuba52014,890.4980
Igarapé Acuruy2,462.1127.1
Putumayo1,813121,115.88,519.9
Tonantins2,955.2169.2
Jutai1,48878,451.54,000
Juruá3,283190,5736,662.1
Uarini7,195.8432.9
Japurá2,816276,81218,121.6
Tefé57124,375.51,190.4
Caiambe2,650.190
Parana Copea10,532.3423.8
Coari59935,741.31,389.3
Mamiá5,514176.2
Badajos41321,5751,300
Igarapé Miuá1,294.556.9
Purus3,382378,762.411,206.9
Paraná Arara1,915.778.2
Paraná Manaquiri1,318.652.9
Manacapuru29114,103559.5
Lower Amazon (Encontro das Águas - Gurupá)
Rio Negro2,362714,577.630,640.8
Prêto da Eva3,039.5110.8
Igapó-Açu50045,994.41,676.5
Madeira3,3801,322,782.432,531.9
Urubu43013,892459.8
Uatumã70167,9202,290.8
Canumã, Paraná do Urariá400127,1164,804.4
Nhamundá, Trombetas744150,0324,127
Curuá48428,099470.1
Lago Grande do Curuaí3,293.692.7
Tapajós1,992494,551.313,540
Curuá-Una31524,505729.8
Maicurú54618,546272.3
Uruará4,610.2104.8
Jauari5,851108.3
Guajará4,243105.6
Paru de Este73139,289970
Xingu2,275513,313.510,022.6
Igarapé Arumanduba1,819.950.8
Jari76951,8931,213.5
Amazon Delta (river mouth to Gurupá)
Braco do Cajari4,732.4157.1
Pará78484,0273,500.3
Tocantins2,639777,30811,796
Atuã2,769119.8
Anajás30024,082.5948
Mazagão1,250.244.4
Vila Nova5,383.8180.8
Matapi2,487.481.7
Acará, Guamá40087,389.52,550.7
Arari1,523.680.2
Pedreira2,00589.9
Paracauari1,390.367.9
Jupati724.232.6

List by length

  1. 6400km (6275to) – Amazon, South America
  2. 3250.km – Madeira, Bolivia/Brazil
  3. 3211km – Purús, Peru/Brazil
  4. 2820.km – Japurá or Caquetá, Colombia/Brazil
  5. 2639km – Tocantins, Brazil
  6. 2627km – Araguaia, Brazil (tributary of Tocantins)
  7. 2400km||sp=us – Juruá, Peru/Brazil
  8. 2250km – Rio Negro, Brazil/Venezuela/Colombia
  9. 1992km – Tapajós, Brazil
  10. 1979km – Xingu, Brazil
  11. 1900.km – Ucayali River, Peru
  12. 1749km – Guaporé, Brazil/Bolivia (tributary of Madeira)
  13. 1575km – Içá (Putumayo), Ecuador/Colombia/Peru
  14. 1415km – Marañón, Peru
  15. 1370.km – Teles Pires, Brazil (tributary of Tapajós)
  16. 1300.km – Iriri, Brazil (tributary of Xingu)
  17. 1240.km – Juruena, Brazil (tributary of Tapajós)
  18. 1130.km – Madre de Dios, Peru/Bolivia (tributary of Madeira)
  19. 1100.km – Huallaga, Peru (tributary of Marañón)

List by inflow to the Amazon

RankNameAverage annual discharge (m3/s)% of Amazon
Amazon209,000100%
1Madeira31,20015%
2Negro28,40014%
3Japurá18,6209%
4Marañón16,7088%
5Tapajós13,5406%
6Ucayali13,5005%
7Purus10,9705%
8Xingu9,6805%
9Putumayo8,7604%
10Juruá8,4404%
11Napo6,9763%
12Javari4,5452%
13Trombetas3,4372%
14Jutaí3,4252%
15Abacaxis2,9302%
16Uatumã2,1901%

See also


Notes


References


Bibliography


External links



Category:Amazon basin
Category:Amazon rainforest
Category:Upper Amazon
Category:Rivers of South America
Category:International rivers of South America
Category:Rivers of Colombia
Category:Rivers of Peru
Category:Colombia–Peru border
Category:Rivers of Amapá
Category:Rivers of Amazonas (Brazilian state)
Category:Rivers of the Department of Loreto
Category:Rivers of Pará