Damming the Mekong would lead to loss of fisheries, reduced agricultural productivity and erosion of river channels and coastline of the Mekong Delta
Visitors look at the shipping locks of the Three Gorges Dam near Yichang, Hubei Province, China. China will move at least four million people in the next decade to protect the ecology of the Three Gorges dam reservoir, Chinese media reported.
By Peter Bosshard (*)
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 that the project has serious social, environmental and geological problems. What are the lessons from the Three Gorges experience?
With a capacity of 18,200 megawatts more than all proposed dams on the lower Mekong's mainstream combined the Three Gorges Dam is a masterpiece of engineering indeed. In spite of its daunting complexity, the government completed the project ahead of time in 2008. Its cost has been estimated at between US$27 billion and $88 billion.
The Three Gorges Dam generates two percent of China's electricity and substitutes at least 30 million tons of coal per year. Yet it was neither the cheapest source of energy nor the best 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 in the US, it would have been "cheaper, cleaner and more productive for China to have invested in energy efficiency" rather than new power plants.
The project's social and environmental cost may be even more staggering than the 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 resettlers as promised.
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 become extinct, and other species are facing 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.
While the social and environmental problems had been predicted, government officials were not prepared for the dam's massive geological impacts. The water level in the Three Gorges reservoir fluctuates between 145 and 175 meters every year. This destabilizes the slopes of the Yangtze Valley, and triggers frequent landslides. According to Chinese experts, erosion affects half the reservoir area, and 178 kilometers of riverbanks are at risk of collapsing. More than 300,000 additional people will have to be relocated to stabilize the reservoir banks.
Since most of the Yangtze's silt load is now deposited in the reservoir, the downstream regions are 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. Because of a lack of nutrients, coastal fisheries have also suffered.
Hydropower projects have often been proposed as a response to global warming, yet the Three Gorges Dam illustrates how the vagaries of climate change create 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, which has again sharply reduced the power generation of the Three Gorges and hundreds of other dams.
Change of course?
Scientists had warned of the Three Gorges Dam's impacts throughout the 1980s and 1990s, but no one listened to them. On May 18, China's highest government body for the first time acknowledged the dam's serious problems. "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."
The Three Gorges Project has served as a model of dam building all around the world. The Son La Dam on the Da River has for example been called "Vietnam's response to the Three Gorges Dam." After the completion of the mega-dam on Yangtze River, the Three Gorges Power Corporation and its contractors started exporting the technology which they had acquired at the Three Gorges to other countries, including Laos, Cambodia and Vietnam.
Given the project's global significance, it is important to draw lessons from the experience with the Yangtze dam. First and foremost, the Three Gorges Project shows that damming the mainstream of major rivers is particularly damaging, in that it will interrupt the migration of fish and the transport of sediments throughout a river's ecosystems. As the World Commission on Dams recommended in its path-breaking report, Dams and Development, a river's mainstream should not be dammed as long as there are other options.
Secondly, the Three Gorges experience demonstrates that large dams on major rivers are massive interventions into highly complex ecosystems. Their impacts can occur thousands of kilometers away and many years after construction has been completed. It is impossible to predict and mitigate all social and environmental impacts of such projects. As a team of international hydrologists coordinated by The Nature Conservancy found in a study in 2010, downstream impacts in particular are often neglected.
A Strategic Environmental Assessment prepared for the Mekong River Commission predicts that damming the lower Mekong mainstream would cause the loss of riverine and marine fisheries, reduce agricultural productivity in Mekong Delta and Cambodia's floodplains, and erode the river channels and coastline of the Mekong Delta. All these impacts have been borne out by the Three Gorges Project. The recommendation by the Commission, and now by the Vietnamese government, not to dam the Mekong for the next 10 years reflects the experience of the Yangtze dam.
Finally, the Three Gorges Dam demonstrates that affected communities and other stakeholders should be involved in decision-making regarding large infrastructure projects from the beginning.
China has a strong state and spent tens of billions of dollars on resettlement programs for the Three Gorges Dam. But because the affected people were excluded from decision-making, the program often ignored their needs and desires, and resulted in wide-spread impoverishment and frustration.
The Chinese government recently started a comprehensive effort to pay pensions to the millions of people who were displaced by its dam projects. It would be cheaper and more effective to give affected people a say in decision-making from the beginning. The civil society consultations on the Xayaburi Dam which the Vietnamese government held earlier this year were a step in the right direction.
(*) Peter Bosshard is the Policy Director of US-based environment NGO International Rivers. The opinions expressed are his own.