Dams: Blessing and Curse for World's Largest Rivers

By J.R. Pegg

WASHINGTON, DC, June 23, 2004 (ENS) - Indiscriminate dam building is threatening many of the world's largest and most important rivers, according to a World Wildlife Fund (WWF) report released Tuesday.

The study cites China's Yangtze as the river most at risk, with 46 large dams planned or under construction.

WWF acknowledges that dams provide benefits for agriculture, flood control, energy production and to water supplies.

With some seven billion people worldwide expected to face water scarcity by 2050, and with two billion currently lacking access to electricity, these benefits are hard to ignore.

But WWF cautions that many projects proceed without mitigation of the negative environmental, economic and social impacts, and much of the water supply is wasted due to inefficiency.

Globally there are more than 45,000 large dams now operational in 150 countries, with an additional 1,500 under construction.

More than 60 percent of the world's major rivers are fragmented because of dams, which have destroyed critical wetlands and fisheries.

"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."

China's Three Gorges Dam on the Yangtze River is slated for completion by 2009 and will be the world's largest dam. (Photo by Michel Gunther courtesy WWF-Canon)

The WWF report, "Rivers at Risk", identifies the top 21 rivers at risk from dams being planned or under construction. WWF produced the report in cooperation with the World Resources Institute.

The study is based on dams that are either higher than 60 meters or will have installed hydropower capacity of more than 100 megawatts.

It documents how dam construction has shifted from the developed world to the developing world, with China and India among the leading dam builders. Current dam building programs target river basins, such as the Yangtze and the Amazon, which are of significance for the survival of global biodiversity, WWF says.

The report concludes that governments are not applying the recommendations of the World Commission on Dams, released in 2000.

The commission was a project of the United Nations that set out in 1997 to review the development effectiveness of large dams and recommend internationally acceptable criteria, guidelines and standards for large dams.

The failure to follow these recommendations, WWF says, results in the benefits of dams often being overtaken by negative environmental and social impacts.

The report notes, for example, that much of the water provided by dams is lost, mainly due to inefficient agriculture irrigation systems. Globally, these systems waste up to 1,500 trillion liters of water each year - equivalent to 10 times the annual water consumption of the entire African continent.

"Dam construction projects often proceed with little attention to cumulative impacts and alternatives," said Collier. "In meeting growing global water and energy needs, we must not destroy the ecosystems that provide clean and sustainable water supplies."

Three Gorges Dam (Photo courtesy Dr. Kamran Nemati)

The first batch of generators began to generate power in 2003. The entire project is to be completed by 2009 when all 26 generators will be able to produce electricity.

When completed, the one and a half mile wide dam will stand more than 600 feet high and will create a reservoir hundreds of feet deep and nearly 400 miles long.

The project's 26 hydropower turbines are expected to produce up to one-ninth of China's electricity, but it will displace some 1.2 million people and will cause major environmental impacts.

The Yangtze River is a center of biodiversity, WWF says, with some 322 species of fish and 169 species of amphibians. Many are already in peril and some, including the Yangtze River dolphin and several species of water birds, could be lost if indiscriminate dam building continues to destroy their habitats.

The report finds some 27 dams are planned or under construction within the La Plata basin in South America, followed by 26 dams within the Tigris and Euphrates Basin in Turkey, Syria, and Iraq.

The next top three river basins slated for dam development are the Salween in China, Thailand and Myanmar, the Kizilirmak in Turkey, and the Ganges in China, Nepal, India, and Bangladesh.

Europe's Danube, South America's Amazon, and Asia's Mekong are also on WWF's list.