What are the disadvantages of hydroelectric power generation?

First of all, we should know the principle of hydropower generation: the basic principle of hydropower generation is to use the water level difference to generate electricity with the hydro-generator, that is, to convert the potential energy of water into the mechanical energy of the hydro-generator, and then use the mechanical energy to drive the generator to generate electricity. Therefore, power generation itself relies on the impact of water to push the turbine, and there is no physical change to the water quality. Disadvantages are: ecological damage: the soil erosion under the dam is intensified, the river changes and its influence on animals and plants. Need dam resettlement and so on. The investment in infrastructure is large, and the fertile alluvial soil in the lower reaches is reduced due to scouring, resulting in changes in water quantity.