Three Gorges Dam : good or not ?

[Maciamo]

The sedimentation problem should not be overlooked. It's not just sediments but also big rocks that are transported by the river. They could block the dam and damage the turbines. If sediments fill up the dam the cost of dredging will be important.
If sediment cannot flo freely along the river, the waters will cause erosion in lieu of fertilizing the plains.

The sediments needed to fertilize the land or prevent erosion will come from the hundreds of tributaries downstream of the dam. Sediments can be evacuated by opening the gates once in a while. Big rocks and so on can be stopped with wire netting, then evacuated too. It's not easy, but the dam will produce 10% of the country's electricity in clean energy. It's worth the effort.

Finally, the ecological issue is serious. There is so much pollution flowing down the Yangtze that the lake created by the dam will quickly become a cesspit devoid of life. How are the Chinese planning to clean up the industrial waste in the new lake ?

Pollution will be created by factories anyway. It won't cause more environmental damage if it stagnates in the lake than if it is allowed to go all the way to the sea. Its just a matter of where the pollution goes, not a matter of quantity. I don't think it is preferable to let heavy chemicals pollute the China Sea, which feeds hundreds of millions of people in China, Korea and Japan and is already overpolluted. The dam might be an opportunity to install water treatment plants - something you cannot do in the sea.

It's hypocritical (or just logically mistaken) to say that the Three Gorges Dam will create more pollution when it facts it will replace lots of highly polluting coal and gas power plants for 100% clean and renewable energy. The pollution in the river is an entirely different problem, which should be solved by asking factories not to discharge toxic waste in the river but send them for recycling instead. You can't blame the dam if factories don't do their job.