Three Gorges Dam: A Blessing or an Environmental Disaster?
October 2, 2007
The world’s largest hydropower dam project could be facing an environmental disaster in the near future if care is not taken to address several serious problems.
p. The Three Gorges Dam located in Southwestern Asia along the Yangtze River, generates electrical power and protects against flooding of the Yangtze River during the rainy season.
p. Environmental concerns caused by the Three Gorges Dam include coastal erosion, landslides, siltation, agricultural and fisheries degradation and species loss.
p. Landslides are one of the biggest threats to the areas surrounding the Three Gorges Dam because of the steep slopes and degradation of the land around the dam. Senior engineer for the dam project, Huang Xuebin, stated that debris that could fall into the dam from a landslide event could raise the water level by dozens of meters, and that this water will cause significant flooding to the surrounding shoreline.
p. Siltation is another major concern because the dam traps silt that would normally flow through.
p. Silt scouring gates are employed to remove silt from within 100 meters of the dam, but these are not guaranteed to be effective because they have not been used on a dam the size of the Three Gorges.
p. The relatively low flow velocity of water moving through the dam may also cause increased siltation problems because it offers more time for the silt to settle out and build up.
Agricultural production may also be adversely affected by the Three Gorges Dam. Silt is one of the main methods of carrying nutrients downstream to farmland, and if silt flow is stopped by the dam, it is likely that agricultural production will decrease due to a lack of nutrients.
p. Almost all dams create erosional problems for the surrounding coastline. If erosion occurs at the Three Gorges Dam it could be devastating for China’s coastal towns, but the Chinese government is not currently projecting that the high rate of siltation will have this effect.
p. Species loss in the dam area may be quite drastic. At least three major species are guaranteed to be negatively affected by the dam construction — the endangered Siberian crane, the Yangtze sturgeon and the Yangtze freshwater dolphin. Around one-half of the total population of Siberian cranes lives in the Three Gorges at the low stand of the Yangtze River. The cranes eat aquatic weeds that grow on the bottom, but as the water gets deeper in the Three Gorges area, the cranes may no longer be able to feed on the weeds.
p. According to the International Rivers Network, hundreds of factories, mines and waste dumps were submerged during the construction of the dam, which is leading to major pollution problems in the Yangtze River and its tributaries. Massive industrial centers upstream are also contributing to pollution problems.
p. During the five-month rainy season, the water levels in the dam are lowered to prevent flooding, which creates a bog of effluent silt and industrial pollutants. This bog creates a breeding ground for flies, mosquitoes, bacteria and parasites, which pose serious risks to human health.
p. The East China Sea was also adversely affected by the construction of the Three Gorges Dam. A decline in freshwater and increase in sediments reaching the East China Sea may cause total annual catches to be reduced by approximately one million tons. Sediment losses are also badly eroding the Yangtze River delta and the tidal wetlands.
p. The potential for the Three Gorges Dam to create serious environmental degradation has been addressed by several groups and people, including Wang Xiaofeng, the director of the administrative office that is in charge of building the dam.
p. “We absolutely cannot relax our guard against ecological and environmental security problems sparked by the Three Gorges Project,” Xiaofeng said in an interview with the Xinhua news agency.
p. The Three Gorges Dam demonstrates the tradeoff between creating an infrastructure that will be able to generate enough electricity to power China into the 21st century and the environmental and ecological devastation that can occur as a result of constructing such an expansive and invasive structure.