River in Madre de Dios, Peru. Click image for related pictures. (Photo by R. Butler)
By Rhett Butler
| Last updated July 31, 2012
Tropical rainforests have some of the largest rivers in the world, like the Amazon, Madeira, Mekong, Negro, Orinoco,
and Congo (Zaire), because of the tremendous amount of precipitation their watersheds receive. These mega-rivers
are fed by countless smaller tributaries, streams, and creeks. For example, the Amazon alone has some 1,100 tributaries,
17 of which are over 1,000 miles long. Although large tropical rivers are fairly uniform in appearance and water
composition, their tributaries vary greatly. Many tropical rivers and streams have extreme high and low water levels
that occur at different parts of the year.
In addition to rivers, rainforests have conventional, free-standing lakes and so-called oxbow lakes, formed when
a river changes course. These lakes are home to species adapted to the quiet, stagnant conditions.
Tropical waters, whether they be giant rivers, streams, or oxbow lakes, are almost as rich in animal species as
the rainforests that surround them. But they, too, are increasingly threatened by human activities, including
pollution, siltation resulting from deforestation, hydroelectric projects, and over-harvesting of resident species.
Waterways off the Rio Negro in Brazil. (Courtesy of NASA)
- Why are some of the world's largest rivers found in tropical regions?
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Selection of information sources
Richard Spruce's opening quotation (made around 1850) is found in One River (New York: Touchstone, 1996) by Wade Davis.
Oil palm, mining prompts local govt in Borneo to declare water unsafe for drinking
(08/06/2014) The Environment Ministry of Sintang Regency, West Kalimantan, Indonesia declared that the water in many rivers and lakes is unsuitable for consumption due to high levels of pollution.
DRC deforestation escalates despite resource shortages, protests, rape, homicide
(07/10/2014) Road construction, the promise of employment, and the conversion of forest to farmland – the effects of logging tropical forests are often not confined to the boundaries of the concessions, where, in the best case, a timber company has gained legal access to harvest trees. Along the Congo River in the northern Democratic Republic of Congo, recent data showing probable forest loss demonstrate the often-unforeseen consequences of timber harvesting.
An end to India's 'Wild West'? Meghalaya bans coal mining... for now
(07/08/2014) Meghalaya, a state in India’s northeast, has thick forests above ground and valuable minerals below. Uncontrolled mining in the area has cleared forests, degraded rivers, and led to many accidents and deaths as few health and safety standards exist for mine workers. A ban effected earlier this year halted all mining in the state, but is set to be reconsidered at a hearing scheduled for August.
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