The Three Gorges Dam on the Yangtze River is the world's largest hydropower project. It has often been touted as a model for dam building around the world. Now the Chinese government has officially acknowledged the project's serious social, environmental and geological problems. What are the lessons from the Three Gorges experience?
For many years, Chinese leaders have celebrated the mega-dam on the Yangtze as a symbol of the country's economic and technological progress. With a capacity of 18,200 megawatts, the hydropower project is indeed a masterpiece of engineering. In spite of its daunting complexity, the government completed it ahead of schedule in 2008. The dam generates two percent of China's electricity, and substitutes at least 30 million tons of coal per year. Its cost has been estimated at between $27 and $88 billion.
Costs and benefits
The social and environmental costs may be even more staggering than the project's financial price tag. The Three Gorges Dam has displaced more than 1.2 million people. Hundreds of local officials diverted compensation money into their own pockets, but protests against such abuses were oppressed. Because it no longer controls the economy and land is scarce, the government was not able to provide jobs and land to the displaced people as promised. Unlike other governments, China has set up a program to provide pensions to the 18 million people displaced by dams in the past.
Damming the Three Gorges caused massive impacts on the ecosystem of the Yangtze, Asia's longest river. The barrage stopped the migration of fish, and diminished the river's capacity to clean itself. Pollution from dirty industries along the reservoir is causing frequent toxic algae blooms. Commercial fisheries have plummeted, the Yangtze river dolphin has already been extinct, and species such as the Chinese Sturgeon are threatened by the same fate. Due to dam building and pollution, rivers and lakes around the world have lost more species to extinction than any other major ecosystem.
Struggling with unexpected impacts
While the social and environmental problems had been predicted, government officials were not prepared for the massive geological impacts of the Three Gorges Dam. The water level in the reservoir fluctuates between 145 and 175 meters every year. This destabilizes the slopes of the Yangtze Valley, and is triggering frequent landslides. According to Chinese experts, erosion affects half the reservoir area, and more than 100 miles of riverbanks are at risk of collapsing. More than 300,000 additional people will have to be relocated to stabilize the banks of the reservoir.
Since most of the silt load from the Yangtze's upper reaches is now deposited in the reservoir, the downstream regions are being starved of sediment. As a consequence, up to four square kilometers of coastal wetlands are eroded every year. The Yangtze delta is subsiding, and seawater intrudes up the river, affecting agriculture and drinking water supplies. An international team of scientists recently found that no less than 472 million people have likely been affected by the downstream impacts of large dams around the world, and that these impacts are often neglected during the planning of such projects.
Scientists agree that the reservoirs of high dams can trigger earthquakes. The Three Gorges Dam sits on two fault lines, and hundreds of small tremors have been recorded since the reservoir began filling. While the dam has been built to withstand strong earthquakes, the villages and towns in its vicinity have not. As global dam building increasingly moves into mountain areas with active tectonic faults, the seismic risks of reservoirs will increase.
Hydropower projects have often been proposed as a response to global warming, yet the Three Gorges Dam illustrates how climate change creates new risks for such projects. In a nutshell, past records can no longer be used to predict a river's future streamflow. The dam operators planned to fill the Three Gorges reservoir for the first time in 2009, but were not able to do so due to insufficient rains. The current year has brought Central China the worst drought in 50 years. Like other projects around the world, the Three Gorges Dam is facing serious risks and losses due to the vagaries of climate change.
A new approach is needed
Scientists had warned of the Three Gorges Dam's impacts throughout the 1980s and 1990s. Yet their opinions were ignored and silenced. During the construction phase, the giant project, which had originally been championed by Mao Zedong, was frequently visited by government and party leaders. It has also served as a tour stop for many visiting government delegations from Asia, Africa and Europe.
In recent years, the Chinese government has quietly toned down its enthusiasm for the project. "We thought of all the possible issues," the secretary general of the Yangtze River Forum told the Wall Street Journal in August 2007. "But the problems are all more serious than we expected." When the dam was inaugurated in 2008, the Chinese president and his prime minister were conspicuously absent. And on May 18, China's highest government body for the first time acknowledged the serious problems at the Three Gorges. "The project is now greatly benefiting the society in the aspects of flood prevention, power generation, river transportation and water resource utilization," the government maintained, but it has "caused some urgent problems in terms of environmental protection, the prevention of geological hazards and the welfare of the relocated communities."
China's economy is booming, and its water and energy needs are pressing. Yet the Three Gorges Dam was not the only option for replacing coal. While the dam was under construction, the country's economy actually became more wasteful in its use of energy. According to the Energy Foundation, it would have been "cheaper, cleaner and more productive for China to have invested in energy efficiency" rather than new power plants.
A few hundred miles from the Three Gorges reservoir, the water works of Dujiangyan have irrigated the fertile Sichuan plains and prevented floods through an ingenious system of levees for more than 2000 years. They reflect the Taoist philosophy of working with the forces of nature, while the Yangtze dam symbolizes the Maoist (and Confucian) approach of subduing the natural world.
The Three Gorges Dam has been completed, but it is not too late to draw lessons for the mega-projects which have been proposed on the Mekong and the Amazon, the Congo and the Salween, in Ethiopia and the Himalayas. The Yangtze dam demonstrates that even with the greatest technical skills, our power to dominate nature is limited. It calls on us to harness our great technological progress for solutions that reduce poverty while respecting the limits of our ecosystems.