New dams are threatening the world's largest rivers

Posted: 28 September 2004

Indiscriminate dam-building is threatening the world's largest and most important rivers, with the Yangtze in China, the La Plata in South America, and the Tigris and Euphrates in the Middle East likely to suffer most from dams, warns a new report.

Rivers at Risk: Dams and the Future of Freshwater Ecosystems, published by WWF and the World Resources Institute, identifies the top 21 rivers at risk from dams being planned or under construction. It shows that over 60 per cent of the world's 227 largest rivers have been fragmented by dams, which has led to the destruction of wetlands, a decline in freshwater species - including river dolphins, fish, and birds - and the forced displacement of tens of millions of people.

The Three Gorges Dam under construction in China. Photo: WWF-Canon / Michel Gunther
The Three Gorges Dam under construction in China. Photo: WWF-Canon / Michel Gunther
The Three Gorges Dam under construction. As well as displacing 1.3 million people and destroying the habitat of many endangered aquatic species, there are now concerns about other environmental effcts. Photo: © WWF-Canon / Michel Gunther
The report highlights the Yangtze as the river at most risk with 46 large dams planned or under construction. The Danube and Amazon rivers are also included in the list. The report concludes that governments are not applying the recommendations of the World Commission on Dams (WCD) to their dam projects. As a result, the benefits that dams provide - such as hydropower, irrigation, and flood control services - are often overtaken by negative environmental and social impacts. For example, much of the water provided by dams is lost, mainly due to inefficient agriculture irrigation systems - which globally waste up to 1,500 trillion litres of water annually. This is equivalent to 10 times the annual water consumption of the entire African continent.

In addition, dam construction affects the livelihoods of millions of people. A recent report by WCD reveals that 40 to 80 million people worldwide, including 10 million in the Yangtze River basin, have been displaced due to dam constuction. The rapid decline of some fisheries, as a result of altered river flows from dam construction, also adversely affects the livelihoods of millions of people that depend on fisheries as their only source of protein, as well as income.

Ecological balance

The report grapples with a fundamental contradiction between dams and ecosystem stewardship, especially in the developing world. According to the UN, more than 2 billion people globally lack access to electricity, 1.1 billion do not have safe drinking water, and 2.4 billion still require adequate sanitation services. Dams provide much needed fresh water for domestic use, crop irrigation, as well as for the mitigation of floods, and hydropower for millions.

"Dams are both a blessing and a curse - the benefits they provide often come at high environmental and social costs," said Dr Ute Collier, head of WWF's Dams Initiative. "Those most affected by dams rarely benefit from them or gain access to power and clean water."

According to the report, downstream communities suffer most from dams, with rivers running dry and fish stocks decimated. Dams disrupt the ecological balance of rivers by depleting them of oxygen and nutrients, and affecting the migration and reproduction of fish and other freshwater species. For example, China - the country with the most number of dams planned or under construction in the world - may lose endangered species such as the Chinese Alligator, the Yangtze River Dolphin (the only freshwater porpoise in the world) and many water birds if indiscriminate dam-building continues to destroy their habitats. WWF, the conservation agency is urging decision-makers and dam developers to make efficient water use a priority by applying internationally accepted standards, such as those of the WCD, on dam projects. The EU Water Framework Directive, for instance, applies strict conditions for the development of dams in EU member states. New projects are allowed only if there are no better environmental options. Such progressive legislation, however, is rare. "Dam construction projects often proceed with little attention to cumulative impacts and alternatives," said Ute Collier. "In meeting growing global water and energy needs, we must not destroy the ecosystems that provide clean and sustainable water supplies." * The list of top 21 rivers at risk from dam construction are:Yangtze, La Plata, Tigris & Euphrates, Salween, Kizilirmak, Ganges, Amazon, Mekong, Brahmaputra, Xun Jiang (Pearl River), Danube, Huang He (Yellow River), Kura-Araks, Yesil-Kelkit, Büyük Menderes, Çoruh, Simav, Ebro, Indus, Qezel Owzan.

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