What are the advantages and disadvantages of the Three Gorges Dam?

The Three Gorges Project is the largest hydropower station in the world and the largest project in China. It is a key measure for comprehensive flood control in the middle and lower reaches of the Yangtze River. It also has huge comprehensive economic benefits such as power generation, shipping, irrigation, water supply, and developing the economy of the reservoir area, which is of great significance to accelerating China's modernization process and improving its comprehensive national strength.

\x0d\ The dam site of the Three Gorges Project is located in Sandouping Town, Yichang County, Hubei Province, more than 40 kilometers away from Yichang City. The project is mainly composed of dams, power plants on both sides of the strait, 26 units, double-track five-level ship locks and other buildings. Total length of the dam1.983m, crest elevation1.85m and maximum dam height1.75m.. The normal water level of the reservoir175m, with a total storage capacity of 39.3 billion cubic meters. The total installed capacity of the hydropower station is17.86 million kilowatts, and the annual power generation is 84 billion kwh, which is equivalent to one-eighth of the national power generation of 199 1 year, six times that of Gezhouba project, and twice that of Gezhouba project. The installed capacity of the Three Gorges Project is almost twice that of Itaipu Hydropower Station in Brazil, the largest hydropower station in the world today. Its 26 hydro-generators with a single capacity of 680,000 kilowatts are almost equivalent to a large hydropower station. China1200 million people increase electricity by 70 kWh per person every year, which is equivalent to building ten Daya Bay nuclear power plants in the south of China. The total static investment of the project is more than 90 billion yuan (1995 price). The construction period of the whole project is 17 years, and the ninth year of the project will benefit from power generation. After the project is completed, it is expected that all the construction funds can be recovered in a short time.

\x0d\ The Three Gorges Project will adopt the construction scheme of "one-stage development, one-time completion, water storage by stages and continuous resettlement" and adopt the construction method of three-stage construction. The normal water level of the reservoir is 175m, and the elevation of the dam crest is 185m.

\x0d\ Engineering advantages:

\x0d\ Flood control: The flood control capacity of the reservoir is 2210.50 billion cubic meters, which can effectively control the upstream flood from entering the middle and lower reaches of the plain. In case of once-in-a-century flood, the discharge of Jingjiang reach can be controlled within a safe range, and Jingjiang flood diversion area is not needed. In case of once-in-a-century flood or 1.870 flood, the flow of Zhicheng station can be controlled not to exceed 80,000 cubic meters per second. It is the most effective measure to alleviate the flood threat in the middle reaches of the Yangtze River and prevent devastating disasters in Jingjiang reach.

\x0d\ Power generation: The installed capacity of the power station is 65.438+0.768 million kilowatts, with an average annual power generation of 84 billion kWh, which can supply power to Central China, East China and East Sichuan. It can replace about 50 million tons of coal every year, which can reduce the pressure of coal transportation in the above areas and reduce the environmental pollution caused by coal burning from thermal power.

\x0d\ Shipping: After the completion of the Three Gorges Project, the backwater of the reservoir will form a 660-kilometer-long deep-water channel, which can improve the channel conditions below Chongqing. With the shallows submerged, the navigation depth increases, the slope slows down and the flow speed decreases, the efficiency of ship transportation will be obviously improved, and the transportation cost will be reduced by 35%~37% compared with the current one, which will greatly accelerate the development of the shipping industry in the Yangtze River. But there are many problems:

\x0d\ For the early completion of the Three Gorges Project, Sichuan, Chongqing, Hubei and other provinces and cities have made great sacrifices, flooded large areas of fertile land and relocated thousands of industrial and mining enterprises.

\ x0d \ 1。 Gravels and pebbles, rather than sediment, are the key bed-making materials affecting the evolution of the upper reaches of the Yangtze River. The Three Gorges area belongs to limestone landform. How can this dam be built to prevent dripping water from passing through the stone? The pressure of that water is so great that the veins in the Three Gorges area are criss-crossed, which is a plate compression area prone to earthquakes. There is so much water in the narrow valley that it is extremely dangerous. After the dam is repaired, none of the pebbles that were originally discharged from Kuimen every year will be discharged. It may block Chongqing Port within ten years and extend upstream year by year, flooding Jiangjin River area in flood season.

\ x0d \ 2。 China is the richest in water resources, ranking first in the world, not the sixth as some people say. What China lacks is to farm where there is water. After the completion of the reservoir, 500,000 mu of land was flooded, and more was used to exchange electricity, which is really not desirable. See On the Relationship between Precipitation and Water Resources for details.

\ x0d \ 3。 Considering the economic feasibility of the Three Gorges Power Station, pebble deposition is untenable, which is two or three times more expensive than large and medium-sized power stations in mountainous areas. The economic accounting in the report is wrong. /kloc-within 0/8 years, only the payment, no output, can not solve the current problem of power shortage.

\ x0d \ 4。 Although the Three Gorges Reservoir has little effect on flood control in the middle reaches of the Yangtze River, it is really undesirable at the cost of prolonging the flood season of dikes and reducing power consumption. Flood control in the middle reaches of the Yangtze River is imminent. In addition to strengthening dikes, it is also necessary to make holes in dikes to divert water and send sand to river banks all the year round, so as to raise depressions and dredge rivers.

\ x0d \ 5。 It is military, and the dam has been the target of potential enemies since its completion. The dam will almost become the target of extortion.

\ x0d \ 6。 It's a flood. It is said that once the dam is completed, it will resist the once-in-a-century flood, and the Yangtze River flood will be cleared at one time. Because the flood in 1998 proves that the Yangtze River flood is not mainly from the main stream above the Three Gorges of the Yangtze River, but from the tributaries east of the Three Gorges. Most tributaries of the Yangtze River are east of the Three Gorges, such as Hanjiang River, Qingjiang River, Xiangjiang River and Ganjiang River. No river is easy to mess with Without the support of many dams on the east tributary of the Three Gorges, the downstream will still be threatened by the tributary flood. As for the loss of cultural relics, it doesn't count.

\ x0d \ 7。 Reservoir inundation of cultivated land, migration and urban relocation will aggravate the already prominent contradiction between man and land, which may aggravate plant damage, soil erosion and ecological deterioration.

\ x0d \ 8。 At present, the annual discharge of industrial and domestic wastewater in the reservoir area has exceeded 1Gt, and some sections of cities along the river have formed serious pollution zones. After the completion of the reservoir, the water flow speed in the reservoir area slowed down, the reoxygenation diffusion ability decreased, and the local water pollution was aggravated.

\ x0d \ 9。 The Three Gorges Project will change the structure and function of aquatic ecosystems in the reservoir area and the middle and lower reaches of the Yangtze River. The living conditions of some rare and endangered species have further deteriorated; It will also adversely affect the natural reproduction of the four major fish.

\ x0d \ 10。 After the operation of the Three Gorges Reservoir, the rivers in the middle and lower reaches of the Yangtze River have undergone erosion and siltation changes. It has a certain influence on the soil fertility and swamp of low-lying farmland in the plain lake area of the middle reaches of the Yangtze River. The harm of seawater intrusion in the downstream estuary may increase. The impact on Shanghai is particularly obvious.

\ x0d \ 1 1。 After the completion of the Three Gorges Dam, the water level in the reservoir area will be raised and widened, some cultural relics along the river will be submerged, and the natural landscape of the Three Gorges will also be affected.

\ x0d \ 12。 After the Three Gorges Project is put into operation, it will lead to sediment deposition and water quality deterioration in Chongqing, and the existing water supply and drainage facilities will be affected.

\ x0d \ 13。 The Three Gorges Project also has a certain impact on local geological disasters and people's health.