River in Madre de Dios, Peru. Click image for related pictures. (Photo by R. Butler)
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RAINFOREST WATERS
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)
Review questions:
- Why are some of the world's largest rivers found in tropical regions?
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WEEKLY NEWSLETTER
INTERACT
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Recent news
Mystery of Amazon River carbon emissions solved
(05/21/2013) Bacteria living in the Amazon River digest nearly all wood plant matter that enters the river before it reaches the Atlantic Ocean, triggering the release of carbon locked up in the vegetation instead of sequestering it in the deep ocean, finds a new study published in Nature Geoscience. The research explains the mechanism by which the world's largest river 'exhales' large amounts of CO2.
China approves another mega-dam that will imperil endangered species
(05/21/2013) Chinese environmental authorities have approved construction plans for what could become the world's tallest dam, while acknowledging that the project would affect endangered plants and rare fish species.
Amazon's flood/drought cycle becoming more extreme, less predictable
(05/14/2013) The Amazon River's hydrological cycle has become more extreme over the past two decades with increasing seasonal precipitation across much of the basin despite drier conditions in the southern parts of Earth's largest rainforest, finds a new study published in Geophysical Research Letters. The research analyzed monthly Amazon River discharge at Óbidos, a point that drains 77 percent of the Amazon Basin, and compared it with regional precipitation patterns.
Rainforest tribe urges Norwegian king to recall energy executive
(05/13/2013) In an unusual bid to stop a series of dams that will flood their rainforest home, a group of tribesmen in Borneo are urging King Harald V of Norway to call one of his subjects home. The subject is Torstein Dale Sjøtveit, a Norwegian citizen who is the CEO of Sarawak Energy, a Malaysian firm that is building several dams in the state of Sarawak. The hydroelectric projects are controversial because they require the forced displacement of indigenous communities and will flood large tracts of rainforest.
Deforestation will undercut effectiveness of rainforest dams
(05/13/2013) Deforestation may significantly decrease the hydroelectric potential of tropical rainforest regions, warns a new study published in Proceedings of the National Academy of Science. The study, used climate, hydrological, and land use models to forecast the impact of potential forest loss on hydropower generation on the Xingu River, a major tributary of the Amazon where the world's third largest dam — Belo Monte — is currently under construction.
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