Advantages and disadvantages of dam construction in the Three Gorges of the Yangtze River

Eco-environmental effects of the Three Gorges Project The eco-environmental effects of the Three Gorges Project refer to the favorable and unfavorable effects of the Three Gorges Project construction on ecology and environment.

1, favorable impact (1) flood control: The construction of the Three Gorges Project can effectively reduce the damage of floods in the middle and lower reaches to the ecological environment and improve the living environment of people in the plain lake area in the middle and lower reaches. (2) Prevention and control of schistosomiasis: The construction of the Three Gorges Project will change the living environment of Oncomelania hupensis in summer and the landing environment in winter, thus contributing to the prevention and control of schistosomiasis in the middle and lower reaches. (3) Reduce the siltation of Dongting Lake: The construction of the Three Gorges Project will reduce the water level in the middle reaches of the Yangtze River during the flood, and reduce the jacking effect of the Yangtze River flood on Dongting Lake, thus reducing the shrinkage and siltation of Dongting Lake. (4) Increase the flow in dry season and improve the water quality: The construction of the Three Gorges Project can adjust the seasonal variation of the Yangtze River runoff, increase the flow in the middle and lower reaches and improve the water quality in dry season. (5) Adjusting the local climate: The construction of the Three Gorges Project has formed a huge artificial lake in the Three Gorges reservoir area, thus adjusting the local climate in the Three Gorges area. (6) Reducing environmental pollution: The use of the Three Gorges hydropower has improved the energy consumption structure in Central and East China. Clean hydropower can replace thermal power and reduce environmental pollution and acid rain. To sum up, the favorable impact of the Three Gorges Project on the ecological environment is mainly in the middle and lower reaches.

2. Adverse effects and measures (1) Subsidence land and cultivated land: land where the reservoir will collapse and cultivated land. (2) Intensifying soil erosion and environmental pollution: In the process of resettlement development and urban relocation, improper handling may lead to new problems such as soil erosion and environmental pollution. (3) Induced geological disasters (earthquake, landslide): Reservoir impoundment changes the original stress balance, which may induce earthquakes and increase the possibility of geological disasters such as landslides on the reservoir bank. (4) Aggravated sediment deposition: Reservoir impoundment will slow down the water flow velocity in the reservoir area and aggravate sediment deposition in the reservoir area and the reservoir tail. (5) The natural landscape is affected to some extent. (6) Impact on species survival: Reservoir impoundment will have a certain impact on the living environment of aquatic organisms and rare species. (7) Increase mosquito breeding: Reservoir storage may increase mosquito breeding and affect people's health. To sum up, the adverse impact of the Three Gorges Project on the ecological environment is mainly in the reservoir area. Two. Countermeasures for ecological environment problems The adverse effects of the Three Gorges Project on the ecological environment in the reservoir area can be divided into three types according to the degree of influence: irreversible, large and small. Table 5-6: Causes, Harms and Countermeasures of Ecological Environment Problems The causes, harms and countermeasures of ecological environment problems are irreversible, but measures can still be taken to remedy or recover some losses. When the flooded farmland reservoir stores water, the water level rises, the cultivated land below the submerged line decreases, and the contradiction between man and land intensifies. Rationally develop existing land resources, develop large-scale agriculture and solve the shortage of cultivated land. When the submerged cultural relics reservoir is filled with water, the water level rises and the submerged cultural relics are destroyed, which hinders the relocation and protection of the submerged cultural relics, thus cutting off the migration and spawning routes of the Chinese sturgeon, affecting the habitat of the baiji and affecting rare species and biodiversity (1). (2) forming a new breeding ground downstream of the dam; (3) The ecological environment problems that can be reversed by establishing Baiji Dolphin Nature Reserve in some reaches of the river have great influence, but those that can be effectively controlled and alleviated by taking measures, such as soil erosion and the contradiction between people and land in the reservoir area, improper rural resettlement development and urban relocation, increased river sediment concentration, and increased sediment deposition in the middle and lower reaches of reservoirs and lakes. Destroy the ecological environment of the reservoir area (1), adjust the agricultural structure, and develop the agricultural production of forest, animal husbandry, fruit, by-products and fishery; (2) Transforming low-and medium-yield sloping farmland and third-rate farmland and developing high-standard terraced fields; (3) Policies and funds are inclined to strengthen ecological environment management and soil and water conservation. The flow conditions of the reservoir with sediment problem have changed greatly after impoundment, which leads to sediment deposition in the reservoir area and the backwater area at the reservoir tail, which affects the service life of the reservoir. Threatening the navigation of Chongqing Port (that is, obstructing navigation) (1) adopts the reservoir operation mode of "storing, clearing and discharging", which makes the sediment inflow and transportation tend to be balanced as a whole; (2) ecological and environmental problems such as port regulation and waterway dredging, and effective measures can be taken to prevent or minimize the harm. Reservoir-induced earthquake affects dam safety (1) The Three Gorges dam site and reservoir area are rare weak earthquake areas; (2) The engineering design has influence on the space for rare terrestrial organisms (1) to transplant in earthquake resistance; (2) artificial cultivation; (3) Establish botanical gardens and protected areas.