Lake Balbina, a man-made reservoir created to supply hydroelectric power to the city of Manaus in Brazil. (Photo courtesy of Jacques Descloitres, MODIS Rapid Response Team, NASA/GSFC). Click image to enlarge.
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DAMS IN THE RAINFOREST
By Rhett Butler | Last updated July 22, 2012
[More on hydroelectric projects]
Large hydroelectric projects — traditionally funded by international aid and development organizations like the World Bank, but increasingly funded by national development agencies and banks like Brazil's BNDES and state-backed banks in China — have led to widespread forest loss. Besides inundating large tracts of rainforest (dams in the lowland areas like much Amazon are generally ecologically inefficient because large tracts of forest are flooded due to the flatness of the basin) and killing off local wildlife, the dams have the effect of destroying aquatic habitats and affecting fish populations, displacing indigenous peoples, and adding carbon to the atmosphere.
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Planned dams in the Amazon Basin, according to the new paper. Click image to expand.
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On top of the ecological damage, several projects have silted up from the erosion resulting from deforestation, rendering the dams inefficient. The reduced water flow downstream disturbs riverbeds and affects floodplain farmers who rely on seasonal floods for nutrients to enrich the soil and kill pests. Thus they may turn to pesticides and artificial fertilizers which have their own negative environmental effects. Diminished water flow can contribute to greater influx of salt water in river deltas, affecting coastal ecosystems essential to fisheries. Hydroelectric projects are also of concern from a health standpoint because they provide opportunities for the spread of disease-carrying organisms including snails (schistosomiasis/bilharzia) and mosquitoes (dengue fever, yellow fever, malaria).
Greenhouse gas emissions from dams
Dams are often touted as sources of "green" energy, but in the tropics, recent research suggests this is a misnomer. Dams in the tropics have two principle greenhouse gas emissions sources: carbon released from soil carbon stocks and dying vegetation when the reservoir is flooded and methane formed where organic matter decays under low oxygen conditions at the bottom of the reservoir. Methane emissions are facilitated by a dam's turbines, which usually draw from the bottom of the reservoir and spray methane-dense water into the air upon release. Emissions from rotting vegetation occur on an ongoing basis when the levels of the reservoir fluctuate: during the dry season weeds, emerge from the muddy drop-down zone, only to rot again when waters return. The effect turns a typical tropical dam into a "methane factory", as coined by Philip Fearnside, a scientist who has published widely on the issue.
An indirect source of emissions from dams is the activity their electricity powers. For example, several major dams in the Amazon are under construction specifically to power mining operations and agroindustry, both of which can drive deforestation. The case is similar in the Malaysian state of Sarawak on the island of Borneo, where hydropower will fuel new mines, ore refiners, and mills for palm oil and paper production.
Dam expansion
Despite vocal objections to many dams from civil society and increased awareness among traditional lenders like the World Bank, the number of planned dam projects in tropical regions is growing. On the Mekong alone, one of tropical Asia's biologically richest rivers, some 11 dams are planned by 2030, while 77 hydroelectric projects are in the works for the Mekong Basin. Meanwhile some 150 dams are planned in the Amazon Basin.
More information on rainforest dams >>
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CONTENTS
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WEEKLY NEWSLETTER
INTERACT
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Recent news
China to build $17B worth of dams in Indonesian Borneo
(06/09/2013) Two Chinese companies — China Power Investment Corporation and Anhui Conch Cement — will invest $17 billion in dams in North Kalimantan, Indonesia's newest province located on the island of Borneo, reports the Jakarta Globe.
Indonesia’s Jatigede Dam Marred by Land Compensation Problems
(06/07/2013) As Indonesia’s controversial Jatigede dam project moves closer to completion, West Java residents whose homes are set to be flooded for the planned 4,973-hectare reservoir brought their complaints to Jakarta, demanding that the country’s president step in to resolve land compensation issues.
Indigenous groups protest hydropower congress as controversy hits meeting in Malaysia
(05/22/2013) The opening of the International Hydropower Association (IHA) World Congress in the Malaysian state of Sarawak was marred today by indigenous protests and controversy after a local indigenous leader was barred from attending a pre-conference workshop. Over 300 people from local indigenous people protested the ongoing construction of around a dozen mega-dams in the state that threaten to flood traditional lands, force villages to move, and upend lives in the state. The Sarawak hydropower plans are some of the most controversial in the world—making the choice of Kuching, Sarawak for the IHA meeting an arguably ironic one—with critics contending that the dams are have been mired in political corruption, including kickbacks and bribes. IHA brings together dam builders, banks, and various related organizations worldwide every two years.
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.
Biosphere conservation: monumental action is critical to avert global environmental crisis
(05/20/2013) Human-caused changes to our biosphere—the global total of the world's ecosystems—are now so great and alarmingly rapid that human lives and societies undoubtedly face epic challenges in the near future as our biosphere deteriorates, planetary boundaries are reached, and tipping points exceeded. We may survive, we may painfully adapt, but it is a fair bet that grave hardship, loss, and sacrifice lay ahead. The nature and extent of impacts among human populations hinges on how successfully we respond to the biosphere crisis with extraordinary leadership, balanced solutions applied at global scales, and unprecedented cooperation—or not.
More rainforest news
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(04/18/2012) More than 150 new dams planned across the Amazon basin could significantly disrupt the ecological connectivity of the Amazon River to the Andes with substantial impacts for fish populations, nutrient cycling, and the health of Earth's largest rainforest, warns a comprehensive study published in the journal PLoS ONE. Scouring public data and submitting information requests to governments, researchers Matt Finer of Save America’s Forests and Clinton Jenkins of North Carolina State University documented plans for new dams in Bolivia, Brazil, Colombia, Ecuador, and Peru.
(04/18/2012) The Xingu River will never be the same. Construction of Belo Monte Dam has begun in the Brazilian Amazon, as shown by these photos taken by Greenpeace, some of the first images of the hugely controversial project. Indigenous groups have opposed the dam vigorously for decades, fearing that it will upend their way of life. Environmentalists warn that the impacts of the dam—deforestation, methane emissions, and an irreparable changes to the Xingu River's ecosystem—far outweigh any benefits. The dam, which would be the world's third largest, is expected to displace 16,000 people according to the government, though some NGOs put the number at 40,000. The dam will flood over 40,000 hectares of pristine rainforest, an area nearly seven times the size of Manhattan.
(03/23/2012) Brazil’s Belo Monte Dam on the Xingu River is now under construction despite its many controversies. The Brazilian government has launched an unprecedented drive to dam the Amazon’s tributaries, and Belo Monte is the spearhead for its efforts. Brazil’s 2011-2020 energy-expansion plan calls for building 48 additional large dams, of which 30 would be in the country’s Legal Amazon region. Building 30 dams in 10 years means an average rate of one dam every four months in Brazilian Amazonia through 2020. Of course, the clock doesn’t stop in 2020, and the total number of planned dams in Brazilian Amazonia exceeds 60.
(06/15/2011) Not far from where the great Amazon River drains into the Atlantic, it splits off into a wide tributary, at first a fat vertical lake that, when viewed from satellite, eventually slims down to a wild scrawl through the dark green of the Amazon. In all, this tributary races almost completely southward through the Brazilian Amazon for 1,230 miles (1,979 kilometers)—nearly as long as the Colorado River—until it peters out in the savannah of Mato Grosso. Called home by diverse indigenous tribes and unique species, this is the Xingu River.
(04/13/2011) As the governments of Laos, Thailand, Cambodia, and Vietnam ready to meet on April 19th to decide whether or not to move forward on the Xayaburi Dam, critics of Mekong River hydroelectric project have warned that the dam will devastate freshwater biodiversity and impact the livelihoods of hundreds of thousands, if not more. Last month a coalition of 263 organizations from 51 countries released a letter in opposition of the dam’s construction.
(03/10/2011) At the end of this month it will be 30 years since Abdul Taib Mahmud came to power in the Malaysian state of Sarawak. Environmentalists are using the occasion, along with new revelations, to highlight corruption and nepotism they say have characterized his regime. Chief Minister Taib and his decades-long administration are no strangers to such allegations, but a new report from the indigenous-rights group Bruno Manser Fund (BMF)—amid criticism from independent media sources, such as Sarawak Report and Radio Free Sarawak—are adding fuel to the fire. Most recently, the report describes in great detail how the tropical timber trade in Sarawak has undercut indigenous groups while toppling some of the world's greatest rainforests, all at the expense of the Sarawak people.
(09/29/2010) Dams, agricultural runoff, pesticides, sewage, mercury pollution from coal plants, invasive species, overconsumption, irrigation, erosion from deforestation, wetland destruction, overfishing, aquaculture: it's clear that the world's rivers are facing a barrage of unprecedented impacts from humans, but just how bad is the situation? A new global analysis of the world's rivers is not comforting: the comprehensive report, published in Nature, finds that our waterways are in a deep crisis which bridges the gap between developing nations and the wealthy west. According to the study, while societies spend billions treating the symptoms of widespread river degradation, they are still failing to address the causes, imperiling both human populations and freshwater biodiversity.
(08/30/2010) The decision last week by the Brazilian government to move forward on the $17 billion Belo Monte Dam on the Xingu river will set in motion a plan to build more than 100 dams across the Amazon basin, potentially turning tributaries of the world's largest river into 'an endless series of stagnant reservoirs', says a new short film released by Amazon Watch and International Rivers.
