Amazon River

• 1. Introduction

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  The Amazon River pushes so much fresh water into the Atlantic that, for centuries, sailors out of sight of land dipped buckets over the side and drank. The Spanish explorer Vicente Yanez Pinzon understood this in March 1500. He named the stream Rio Santa Maria del Mar Dulce, sweet sea, because its freshwater shoved out into the ocean. It is the largest river by discharge volume of water in the world. Its average discharge runs greater than the next seven largest independent rivers combined. Two of the top ten rivers by discharge are merely its tributaries. Yet the most basic facts about it remain unsettled. Where does it begin. How long is it. Whether it or the Nile is the longest river on earth is a dispute geographers have argued for many years. This documentary follows the water from a snowcapped Peruvian peak to a mouth so wide its width is itself a matter of disagreement. Along the way it passes vanished civilizations, a rubber boom that made a jungle town cosmopolitan, and a dolphin that turns pink as it ages.

• 2. The Contested Source

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  For nearly a century, the headwaters of the Apurimac River on Nevado Mismi in Peru were considered the Amazon basin's most distant source. Studies kept confirming it, as recently as 1996, 2001, 2007, and 2008. They identified the snowcapped peak of Nevado Mismi, 5597 m high, roughly 160 km west of Lake Titicaca and 700 km southeast of Lima. From there Quebrada Carhuasanta emerges, joins Quebrada Apacheta, and eventually feeds the Rio Apurimac.

  A 2014 study overturned this. Americans James Contos and Nicolas Tripcevich, publishing in Area, a peer-reviewed journal of the Royal Geographical Society, found the most distant source actually lies in the Rio Mantaro drainage. They measured the Mantaro against the Apurimac from their most distant points to their confluence, and the Mantaro proved longer. The most accurate method was direct GPS measurement by kayak descent of each river, performed by Contos.

  The class IV-V nature of these rivers made the work difficult, especially in their lower Abyss sections. Their conclusion moved the source nearly 80 km farther upstream, to the Cordillera Rumi Cruz. The maximal length of the river grew by about 80 km. Contos then continued downstream to the ocean and finished the first complete descent of the Amazon from its newly identified source in November 2012.

• 3. How Long Is It

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  The Amazon has been reported as anywhere between 6275 km and 6992 km long, often said to be at least 6400 km. The Nile is reported anywhere from 5499 to 7088 km, often said to be about 6650 km. The position of the source, the position of the mouth, the scale of measurement, and the measuring technique all shift the answer.

  In July 2008, the Brazilian Institute for Space Research, INPE, claimed the Amazon was 140 km longer than the Nile. Their figure of 6992 km took the Apacheta Creek as source, and they measured down through tidal canals around the isle of Marajo, including the marine waters of the Rio Para bay. By the same techniques they put the Nile at 6853 km.

  In June 2007, Guido Gelli, director of science at the Brazilian Institute of Geography and Statistics, told a London newspaper the Amazon could be considered the longest river in the world. Neither claim was published, and questions were raised about the methodology. In 2009, a peer-reviewed article reached the opposite finding, giving the Nile 7088 km and the Amazon 6575 km. The Encyclopaedia Britannica holds that the final length remains open to interpretation.

• 4. The Backward River

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  For millions of years the Amazon flowed in the opposite direction, from east to west, draining toward the Pacific. The river originated as a transcontinental river in the Miocene, between 11.8 million and 11.3 million years ago. Its proto form during the Cretaceous ran west, part of a proto-Amazon-Congo system, when the continents were joined as western Gondwana.

  Eighty million years ago, the two continents split. Fifteen million years ago, the main tectonic uplift of the Andean chain began, driven by the subduction of the Nazca Plate beneath the South American Plate. The rising Andes blocked the flow to the Pacific and forced the water to reverse toward its current mouth in the Atlantic.

  The blocked river turned the Amazon Basin into a vast inland sea, then a massive swampy freshwater lake, and the marine inhabitants adapted to life in fresh water. Between eleven and ten million years ago, waters worked through sandstone from the west and the river began flowing eastward, giving rise to the rainforest. The Amazon took its present shape about 2.4 million years ago in the Early Pleistocene. Paralleling it underground runs a large aquifer dubbed the Hamza River, whose discovery was made public in August 2011.

• 5. Cities Before The Conquest

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  By the time the Spanish conquistador De Orellana crossed the Amazon in 1541, archaeologists estimate more than 3 million indigenous people lived around it. These were not scattered bands. The areas surrounding the river held complex, large-scale societies, mainly chiefdoms that developed towns and cities. On the island of Marajo, pre-Columbian people may have built social stratification and supported a population of 100,000.

  Shell mounds are the earliest evidence of habitation, piles of human refuse dated mainly between 7500 BC and 4000 BC. Artificial earth platforms built for entire villages came next, best represented by the Marajoara culture. Figurative mounds are the most recent type.

  To feed such populations, the inhabitants altered the forest itself. By repeatedly burning areas of forest, they enriched the soil, creating dark earth known as terra preta de indio, Indian black earth. Research has hypothesized this practice began around 11,000 years ago. Some say its effects on forest ecology and regional climate explain an otherwise inexplicable band of lower rainfall through the basin. Warfare was constant. According to James S. Olson, the Munduruku expansion in the 18th century broke the Kawahib into much smaller groups.

• 6. The Naming

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  Native warriors led by women attacked a 16th-century expedition under Francisco de Orellana, and the spectacle reminded him of the Amazon warriors of Greek mythology, a tribe of women fighters linked to the Iranian Scythians and Sarmatians. From that encounter came the name Rio Amazonas.

  The word Amazon may derive from the Iranian compound ha-maz-an, meaning one fighting together, or the ethnonym ha-mazan, warriors. It is attested indirectly through a gloss by Hesychius of Alexandria, hamazakaran, to make war in Persian, sitting alongside the Indo-Iranian root kar, to make, the same root from which Sanskrit karma derives.

  Europeans first knew the river as the Maranon. The Peruvian part still carries that name, as does the Brazilian state of Maranhao, which contains part of the Amazon. Only later did it become the Rio Amazonas in Spanish and Portuguese. Francisco de Orellana, who traveled from the Andean origins all the way to the mouth, baptized affluents along the way, including the Rio Negro, the Napo, and the Jurua.

• 7. Hunger On The Napo

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  On the 26th of December 1541, Francisco de Orellana took about 57 men, a boat, and some canoes and left Gonzalo Pizarro's troops behind. Pizarro had set off that year east of Quito, searching for El Dorado, the city of gold, and La Canela, the valley of cinnamon. Acting on intelligence from a captive native chief named Delicola, the party expected to find food within a few days downriver.

  Orellana missed the confluence, probably with the Aguarico, where supplies were supposed to be. By the time the men reached another village, many were sick from hunger and from eating noxious plants, near death. Seven men died there. The party stood over 100 leagues downstream, and the men threatened to mutiny if forced to turn back.

  Orellana changed the mission to discovering new lands for the king of Spain. After 600 km down the Napo, they reached a major confluence near modern Iquitos, then followed the Solimoes a further 1200 km to the Rio Negro near modern Manaus, reaching it on the 3rd of June 1542. They reached the mouth on the 24th of August 1542. Pizarro reported to the king that the cinnamon trees they found could not be profitably harvested, because true cinnamon is not native to South America.

• 8. Rubber And Steam

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  On the 6th of September 1850, Emperor Pedro II of Brazil sanctioned a law authorizing steam navigation on the Amazon, and gave the Viscount of Maua, Irineu Evangelista de Sousa, the task of carrying it out. He organized the Companhia de Navegacao e Comercio do Amazonas in 1852, and the next year it began with four small steamers, the Monarca, the Cameta, the Marajo, and the Rio Negro.

  Demand for natural rubber transformed the river economy. The Peruvian city of Iquitos became a thriving, cosmopolitan center of commerce. In 1851 it held a population of 200; by 1900 it reached 20,000. In the 1860s about 3,000 tons of rubber were exported annually, and by 1911 that had grown to 44,000 tons, representing 9.3 percent of Peru's exports.

  The boom carried a death toll. During it, diseases brought by immigrants, such as typhus and malaria, killed an estimated 40,000 native Amazonians. Earlier, the Cabanagem revolt of 1835 to 1840 had been directed against the white ruling class. It is estimated that from 30 to 40 percent of the population of Grao-Para, around 100,000 people, died in it.

  In the 1940s, wary of foreign exploitation, Brazilian governments set out to develop the interior. President Getulio Vargas was the original architect, funded by Allied demand for rubber during World War II. In the 1960s, Operation Amazon brought large-scale agriculture and ranching to the region through credit and fiscal incentives.

  The 1970s brought a new approach, the National Integration Program. Families from northeastern Brazil were relocated to what was called the land without people, paired with infrastructure projects, chiefly the Trans-Amazonian Highway. 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 the Manaus to Porto Velho route, sit derelict and impassable in the rainy season. The colonization program failed because settlers were unequipped to live in the delicate rainforest ecosystem. The government believed the land could sustain millions; instead it could sustain very few. Today Manaus, with 1.9 million people in 2014, is the largest city on the river, and makes up roughly half the population of the state of Amazonas.

  At Manaus, the darkly colored water of the Rio Negro meets the sandy-colored Rio Solimoes, and the two run side by side for over 6 km without mixing. Brazilians call this the Meeting of Waters, the Encontro das Aguas. Above this point Brazil calls the upper river the Solimoes; below it begins what Brazilians call the Amazon proper.

  The river's behavior is governed by flood. Every year it rises more than 9 m, drowning the surrounding forests known as varzea, the most extensive flooded forest in the world. In an average dry season, 110,000 km2 of land lie underwater; in the wet season the flooded area climbs to 350,000 km2. Not all tributaries flood at once. The Madeira rises and falls two months earlier than most of the rest.

  Navigation depends on depth. Large ocean steamers can reach Manaus, 1500 km upriver. Smaller ocean vessels below 9000 tons can reach Iquitos, 3600 km from the sea. There are no bridges across the entire width of the river, not because it is too wide, but because it runs through rainforest with few roads and cities. The Manaus Iranduba Bridge spans only the Rio Negro, just before its confluence.

  Belem is the major city and port at the mouth, where the river meets the Atlantic. Defining where the mouth lies, and how wide it is, is a matter of dispute because of the area's peculiar geography. The Para and the Amazon connect through channels called furos near the town of Breves, and between them lies Marajo, the world's largest combined river and sea island.

  The numbers swing wildly with the definition. Including the Para river and Marajo's ocean frontage, the estuary spans some 325 km. A more conservative measurement, excluding the Para estuary, still gives a width of over 180 km. If only the main channel counts, between the islands of Curua and Jurupari, the width falls to about 15 km.

  The Atlantic is too turbulent to let sediment settle, so the Amazon, unlike other great rivers, forms no significant delta. Instead its plume of fresh water runs about 400 km long and 100 to 200 km wide, altering salinity and the color of the ocean surface over an area up to 2,500,000 km2. At high tide a tidal bore called the pororoca races up the delta, its leading wave up to 25 ft high, traveling up to 500 mi inland.

  The boto, the Amazon river dolphin, grows to lengths of up to 2.6 m, the largest river dolphin species. Its skin changes with age. Young animals are gray, then turn pink, then white as they mature. They use echolocation to navigate the river's tricky depths. In Brazil the boto is the subject of a legend about a dolphin that turns into a man and seduces maidens by the riverside.

  More than one-third of all known species in the world live in the Amazon rainforest, the richest tropical forest on earth for biodiversity. More than 5,600 fish species were known, with roughly fifty new ones discovered each year. The arapaima, called pirarucu in Brazil, reaches up to 15 ft, among the largest freshwater fish in the world. The goliath catfish, the kumakuma, can reach 3.6 m and 200 kg.

  Larger animals share the water with stranger ones. The electric eel and more than 100 species of electric fishes inhabit the basin. The bull shark, able to thrive in both salt and fresh water, has been reported 4000 km up the river at Iquitos. The giant otter, sometimes called the river wolf, is one of South America's top carnivores, now listed on Appendix I of CITES, which effectively bans its international trade.

  The Amazon serves as a lifeline for more than 47 million people in its basin, and the pressures on it are mounting. According to the Office of the United Nations High Commissioner for Human Rights, the Yanomami, a tribe of roughly 30,000, struggle to preserve their land and way of life against encroaching illegal gold miners, malnutrition, and malaria.

  The water itself is changing. In 2022, severe drought drove water temperatures to 39.1 degrees Celsius, killing 125 Amazon river dolphins. In recent years the river has fallen to historically low levels, the lowest in over a century. Brazil, the primary custodian of the river, faces the task of mitigating the effects of drought on communities and ecosystems.

  The main river remains undammed, but around 412 dams operate on its tributaries, 151 of them on six of the main tributary rivers. Only 4 percent of the Amazon's hydropower potential has been developed, and hundreds more dams are planned. Scientists, having watched the Three Gorges Dam on the Yangtze block fish-spawning runs and reduce vital nutrient flows, fear the same harm here. They warn that more damming could bring the end of free flowing rivers and an ecosystem collapse.