what are the advantages ad disadvantages of the Three Gorges Dam project?

Obviously, its biggest advantage is to generate electricity. And it can also prevent the floods that used to damage the places in the lower reaches of the Yangtze River. By the way, the dam is also a popular tourist attraction. However, it says that the dam has great impact on the environment along the Yangtze River. For example, Poyang Lake dries up frequently in recent years.