Nothing is perfect; dams have deficiencies either. There is an example—“the building of the Hoover Dam in the USA triggered a number of earthquakes and has depressed the earth’s surface at its location.” Constructing a hydropower on the river will certainly cause a lot of problems. Perhaps these problems will not as serious as the example, but people still need to pay for them. First, from an economic point of view, the cost of building a dam is extremely expensive. The Longtan Dam spent approximately 30 billion yuan (3.75 billion usd). Therefore, for some underdeveloped countries, a hydropower project could be a difficult domain to involve. Secondly, the dam severely damages the local natural environment and biosphere. Many fish or other
