The impact of the Three Gorges Dam

1. Early estimates of flood control capabilities were too optimistic

When the Three Gorges Project was launched, the primary function of publicity was to once and for all solve the flood problem in the middle and lower reaches of the Yangtze River. The slogan of the year was "The day the Three Gorges Project is completed will be the day when the Yangtze River bids farewell to floods."

However, judging from media publicity, this slogan has become more and more low-key after its completion. When it was completed in 2003, it was said that "the Three Gorges Dam is impregnable and can withstand a once-in-ten-million-year flood." However, in 2008 it became "The Three Gorges Dam can withstand a once-in-a-century flood." Last year, it was declared that "we cannot rely entirely on the Three Gorges Dam to fight floods this year."

2. Solving sedimentation is not as smooth as expected

Dam sedimentation is a major problem in water conservancy construction. According to reports, the Three Gorges Reservoir adopts the method of "accumulating clear water and discharging muddy water". To deal with the problem of sediment discharge, that is, increasing the drainage volume to allow muddy water to flow out of the reservoir during the flood season, and accumulating a large amount of clean water during the dry season, can reduce the sedimentation of sediment in the reservoir. This is considered to be a major pioneering work in the history of water conservancy. However, recent reports pointed out that based on early monitoring of the reservoir's operation, this method can only discharge about 70% of the sediment. According to monitoring, since the impoundment, from 2003 to 2007, 200 million tons of sediment have entered the reservoir every year, and about 130 million tons have been deposited in the reservoir.

3. Water transfer and power generation still need to be coordinated

The biggest feature of water conservancy projects is to reduce the abundance and replenish the dryness, and adjust the balance of floods and droughts. But for the Three Gorges Company, power generation is their source of income, and there is a certain contradiction between it and water transfer. Wang Jingquan, deputy inspector of the Flood Control and Drought Relief Office of the Yangtze River Water Conservancy Commission, said in an interview about this year's drought that due to the previous "off-season peak power consumption" "Allowing the Three Gorges to use a large amount of water to generate electricity has aggravated the drought downstream. Wang Yintang, director of the Hydrological Basic Theory Research Office of the Water Resources Research Institute of the Nanjing Institute of Water Resources, also believes that because the Three Gorges Project serves as a hub for both water conservancy and hydropower, its large volume of water for power generation will objectively cause "water shortage" downstream.

2. Environmental impact: may be exaggerated, but still serious

The drought is believed to be related to the Three Gorges Project

1. The accusation of "climate impact" lacks basis

In recent years, abnormal weather has occurred frequently in southern China. Sichuan and Chongqing and other places have experienced abnormal weather such as intense heat, severe drought, and heavy rains. The Three Gorges has often been targeted. The basic conclusion of the "Environmental Impact Report of the Three Gorges Water Conservancy Project on the Yangtze River" reviewed and approved by the State Environmental Protection Administration is that after the construction of the Three Gorges reservoir, the impact on temperature, humidity, wind and fog in the reservoir area and adjacent areas will generally not exceed 10 kilometers. Zheng Guoguang, a member of the National Committee of the Chinese People's Political Consultative Conference and director of the China Meteorological Administration, said that some people believe that the Three Gorges reservoir area has had a serious impact on the climate of the vast areas surrounding the Three Gorges, and attribute some extreme weather and climate events to the impact of the Three Gorges Project. This has no scientific basis. .

2. The task of environmental management in the reservoir area is arduous.

According to the "Yangtze River Protection and Development" jointly issued by the Chinese Academy of Sciences, World Wildlife Fund, Yangtze River Water Conservancy Commission and other units in 2007 Report 2007" shows that the pollution problem in the Three Gorges Reservoir area is serious. After the Three Gorges reservoir area was impounded to 135 meters in 2003, monitoring results showed that during and after the impoundment of 135 meters of water, the Xiangxi River and other 12 Algae blooms (excessive algae reproduction) occurred in various tributaries, and the water flow in the backwater areas slowed down, reducing the pollution-holding capacity of the coastal waters around the reservoir and the reservoir bay. At the same time, a large number of immigrants reclaimed wasteland, which also aggravated water pollution and caused soil erosion. According to the report, ground pollution sources are the main source of pollution in the Three Gorges Reservoir area, accounting for 60% to 70% of the total pollution, mainly from the use of pesticides and chemical fertilizers in the reservoir area.

3. Compared with earthquakes, landslides are a geological impact that deserves more attention

The Three Gorges Project was once accused of being one of the causes of earthquakes in the reservoir area. In fact, the relationship between dams and earthquakes It cannot be proven with current observation methods, but landslides are already a problem worthy of attention. According to a Xinhua News Agency reporter, statistics from the Chongqing reservoir area show that as of March 18, 2009, due to the impact of experimental water storage and water withdrawal, 14 districts in the Chongqing reservoir area, including Wushan, Wuxi, Fengjie, Yunyang, Kaixian, and Wanzhou, have There were 166 geological disasters (dangers) in the county. The total volume of landslides was about 60.24 million cubic meters, affecting 11,535 people and causing land losses of about 2,380 acres. It is worth noting that among the 166 disaster (danger) situation points, there are 121 new sudden disaster (danger) situation points. The Three Gorges Reservoir stores water from 145 meters to 175 meters every year, and then drops back to 145 meters. The resulting 30-meter drop is equivalent to a once-in-a-century Yangtze River flood. The test on the reservoir bank slope can be imagined.

Third, the role of shipping still needs long-term development

Chongqing has not welcomed the giant ship of 10,000 tons

1. "Direct shipping of giant ships to Chongqing" is currently difficult to achieve

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During the design and demonstration process of the Three Gorges, an attractive blueprint of "a 10,000-ton ship reaching Chongqing" was once proposed. However, in fact, the cross-river bridges in the middle and lower reaches of the Yangtze River have already formed hundreds of bridges locking the river, making it impossible for giant ships to pass under the bridge. Pass through and enter the upper reaches of the Yangtze River.

As for the idea of ??"giant ships entering Chongqing", the emergence of the Three Gorges has straightened out the upstream waterway, and whether the downstream bridges should be demolished to make way for ships has caused ongoing debate.

2. Shipping efficiency needs to be further improved

According to public information, the one-way throughput capacity of the Three Gorges Ship Lock was determined at the beginning to be 50 million tons per year, and the two-way operation capacity was 100 million tons. In fact, since the opening of the five-level Three Gorges Ship Lock, the two-way ship lock's throughput capacity has reached saturation at 50 million tons. Moreover, since the permanent ship lock is divided into five levels, the traffic speed is relatively slow. In theory, it takes 2 hours and 40 minutes to pass through the lock. In current actual operation, it often takes more than 3.5 hours to pass. The Chongqing Municipal Transportation Department proposed to demonstrate, plan and eventually build a second double-line five-level ship lock or a second ship lift on the Three Gorges Dam as soon as possible, saying that "this is the fundamental way to open the bottleneck of navigation in the Yangtze River."