What geological factors should be considered during the construction of the Three Gorges Project?

1. The ecological and environmental effects of the Three Gorges Project The ecological and environmental effects of the Three Gorges Project refer to the beneficial and adverse effects of the construction of the Three Gorges Project on the ecology and environment. 1. Beneficial impacts (1) Flood control: The construction of the Three Gorges Project can effectively reduce the damage caused by floods to the ecology and environment in the middle and lower reaches, and improve the living environment of people in the plain and lake areas of the middle and lower reaches. (2) Prevention and treatment of schistosomiasis: The construction of the Three Gorges Project will change the living environment of snails in the "summer water and winter land", which will be beneficial to the prevention and control of schistosomiasis in the middle and lower reaches. (3) Reduce siltation of Dongting Lake: The construction of the Three Gorges Project has lowered the water level in the middle reaches of the Yangtze River during floods, reducing the supporting effect of the Yangtze River floods on the water of Dongting Lake, thus reducing the shrinkage and sedimentation of Dongting Lake (4 ) Increase dry season flow and improve water quality: The construction of the Three Gorges Project can adjust seasonal changes in the Yangtze River runoff, increase dry season flow in the middle and lower reaches, and improve dry season water quality. (5) Adjust local climate: The construction of the Three Gorges Project has formed a huge artificial lake in the Three Gorges reservoir area, thus regulating the local climate in the Three Gorges area. (6) Reduce environmental pollution: The use of Three Gorges hydropower has improved the energy consumption structure in central and eastern China. Clean hydropower can replace thermal power and reduce environmental pollution and acid rain hazards. In summary, the Three Gorges Project’s beneficial impact on the ecological environment is mainly in the middle and lower reaches. 2. Adverse impacts and measures (1) Submerged land and cultivated land: Reservoir water storage will sink land and cultivated land. (2) Exacerbating water and soil erosion and environmental pollution: During the process of resettlement development and urban relocation, improper handling may cause new problems such as water and soil erosion and environmental pollution. (3) Inducing geological disasters (earthquakes, landslides): Reservoir water storage changes the balance of the original stress, which may induce earthquakes and increase the possibility of landslides and other geological disasters on the reservoir bank. (4) Increased sedimentation: The reservoir impounds water, which slows down the water flow in the reservoir area and aggravates the sedimentation in the reservoir area and tail. (5) The natural landscape will be affected to a certain extent. (6) Impact on the survival of species: Reservoir water storage will have a certain impact on the living environment of aquatic organisms and rare species. (7) Increased mosquito breeding: Reservoir water storage may increase mosquito breeding and have an impact on human health. To sum up, the adverse impact of the Three Gorges Project on the ecological environment is mainly in the reservoir area. 2. Countermeasures for Ecological and Environmental Problems The adverse impact of the Three Gorges Project construction on the ecological environment of the reservoir area can be divided into three types: irreversible, large impact and small impact according to the degree of impact. Table 5-6: Causes, hazards and prevention and control measures of ecological environment problems Causes, hazards and countermeasures of ecological environment problems Ecological and environmental problems that are irreversible, but measures can still be taken to remedy or recover part of the losses Ecological and environmental problems Sunken farmland reservoir storage Water, the water level rises, and the cultivated land below the sinking line is flooded and reduced, exacerbating the contradiction of more people and less land, rationally develop existing land resources, develop large-scale agriculture, and solve the shortage of cultivated land.

Sunken cultural relics and historic sites are impounded. The water level rises. The sunken cultural relics and historic sites are damaged. The relocation and protection of flooded cultural relics and historic sites affects rare aquatic organisms. The blocking effect of the Three Gorges Dam blocks the migration and spawning routes of Chinese sturgeons. , affecting the habitat of baiji dolphins and affecting rare species and biodiversity (1) Adopting artificial breeding measures; (2) Forming new breeding sites in the river section downstream of the dam; (3) Establishing baiji dolphin nature reserves in some river sections can Reverse ecological environment problems that have a greater impact, but measures can be taken to effectively control and mitigate their adverse effects. Ecological and environmental problems, water and soil erosion, and conflicts between man and land in the reservoir area. Rural immigration, development, and urban relocation. Improper handling. Increased sediment content in rivers, exacerbating the reservoir. and siltation in the middle and lower reaches of the lake area; destroying the ecological environment of the reservoir area (1) Adjusting the agricultural structure and developing agricultural production of forestry, animal husbandry, fruit, sideline and fishery; (2) Transforming medium and low-yield slopes and three-run fields, and developing high-standard horizontal terraces; (3) Policies and funding are given to strengthen ecological environment management and soil and water conservation. Sediment issues have changed dramatically after the reservoir was impounded, resulting in sedimentation in the reservoir area and the backwater area at the end of the reservoir, affecting the service life of the reservoir; threatening Chongqing. Port navigation (i.e. navigation obstruction problem) (1) Adopt the reservoir operation method of "accumulating clear water and discharging sediment" to make the overall balance between incoming sand and sand transport; (2) The impact of port improvement and channel dredging will be small and effective measures can be taken Ecological and environmental issues that prevent hazards from occurring or minimize hazards. Reservoir-induced earthquakes affect dam safety. (1) The Three Gorges Dam site and the reservoir area are rare weak seismic areas; (2) Engineering design leaves room for earthquake resistance, which affects rare Terrestrial organisms (1) Transplantation; (2) Artificial cultivation; (3) Establishment of botanical gardens and protected areas