Using the Three Gorges Dam on China's Yangtze River as an example, what are the benefits and costs associated with building dams?

Question

What will be an ideal response?

Answer 1

Dams generate hydroelectric power, enable boats and barges to travel farther upstream, and provide flood control and water for irrigation. The power generation may be enough to replace dozens of large coal or nuclear plants. One of the costs of the Three Gorges Dam, aside from its $39 billion construction price tag, is that its reservoir flooded 22 cities and the homes of 1.24 million people, requiring the largest-ever resettlement project. The reservoir behind the dam also inundated archaeological sites 10,000 years old and submerged productive farmlands and wildlife habitat. In addition, the reservoir slows the flow of the river so much that suspended sediment settle and begin to fill the reservoir, rather than being carried to tidal marshes at the mouth of the Yangtze River. Other scientists worry about water quality, saying that the Yangtze's many pollutants will be trapped in the reservoir, making the water even more undrinkable than it already is, but the Chinese government plans to invest $5 billion into building hundreds of sewage treatment and waste-disposal facilities.