High school geography, pros and cons of building a reservoir

Benefits: It can prevent floods and adjust the runoff of the river, change the uneven seasonal distribution of flow, and raise the water level in the reservoir area and upstream areas. It is beneficial to shipping and can also be used as a water source for populated areas and tourist attractions.

Disadvantages: For inland rivers, it may cause damage to the downstream ecology. For outflow rivers, reservoirs can lower the water level downstream and reduce the amount of sand, causing the river bed to deepen, causing the salinity of the river mouth to increase, the salinity of groundwater to increase, and the salinization of the land to occur. Moreover, there will also be sedimentation in the reservoir area, and geological disasters may occur. Resettlement is also required. Rising water levels in the reservoir area may submerge ancient monuments, and rising water levels may have an impact on the rivers above the dam.