Three Gorges Probe
October 26, 1998
This year’s flood disasters in China have prompted a vociferous debate on the Internet among expatriate Chinese communities in North America. Several high-circulation on-line magazines have weighed in on the subject with lengthy articles and interviews, particularly with reference to the issue of dubious flood control benefits of the Three Gorges project.
An interview with a Chinese hydrologist published in the September issue of China Monthly has attracted considerable attention. Wang Weiluo, who reportedly was a participant in the Three Gorges Project during the 1980’s, argues in the magazine that the mega dam does not possess the capacity to contain flood waters. In fact, Wang reinforces the viewpoint of many dam opponents who believe that the Yangtze reservoir may very well put the upstream city of Chongqing under a flood threat if it is used to hold back waters protecting the city of Wuhan downstream.
Wang says that the Three Gorges dam proponents falsely propagate the idea that the dam is designed to prevent the flood of the century. While the very worst flood in Chinese history carried about 160 billion cubic metres of runoff waters, according to historical data, the Three Gorges reservoir only has a flood control capacity of only 22.1 billion cubic metres. This year alone, there were eight flood crests. "Which peaks of water are you going to keep in the reservoir? What will happen when there is a flood peak after the reservoir is full?" asks Wang.
Wang argues that even the reservoir’s capacity of 22.1 billion cubic metres cannot necessarily be guaranteed in flood seasons. This is because dam operators usually keep reservoirs at full capacity in order to produce electricity. The higher the water level, the more electricity it generates. In a flood season dams have to release water in order to contain the flood. Wang poses the question: "When is the right time to release the water in the reservoir?"
According to Wang, the ancient Chinese did not construct any dams and were hardly even acquainted with the idea of dams. In 1949 when the Communists came to power, China had in operation about 30 reservoirs, all of them built by the Japanese during their occupation of China during World War II. Their main function was to generate electricity. By 1997, the number of reservoirs had increased to 86,000, making China the world’s leading nation in its number of hydro-electric dams. It is Wang’s argument, however, that the more dams that China built, the larger the flood control capacity grew, and the greater the flood damages became. The reason? All of these dams were built for producing electricity, and as a result did not function properly as flood control facilities.
Wang points to the example of this year’s flooding in the lower Yangtze region. These areas possess a considerable number of dams for flood control, but many of them failed in their designed function — primarily because of the conflicting interests of generating electricity and controlling floods. According to Wang, there was a palpable surplus of electricity along the middle and lower reaches of the Yangtze River between the end of 1997 and the beginning of 1998. Many hydro-electric plants were ordered to stop generating power temporarily. To make up for losses in electricity revenue, though, these hydro dams operators maintained their reservoirs at full capacity.
Although the National Flood Control Headquarters requested that all the reservoirs release their waters by the end of June in order to store the flood water, many hydro stations failed do so. Case in point: Danjiang Kou Reservoir, which has a flood control capacity of 7.8 billion cubic metres. When the flood was unleashed, though, it could only contain 1.1 billion cubic metres of water. This is because it had already devoted 6.7 billion cubic metres of water to electricity purposes.
Wang also criticizes the Ministry of Water Resources for allowing the settlement of large populations in flood diversion zones along the Yangtze River, which consequently led to a paralysis in flood management capacity in the region. It his view that the ministry did this deliberately during the 1960’s and 1970’s in order to escalate the threat of flooding and, thereby, make a case for the Three Gorges Project.
Many flood overflow diversion zones, such as the Jingjiang overflow diversion zone, the Honghu zone and the Du Jiatai zone, were established in the early 1950’s. At that time, these zones were mostly empty land, although some small settlements had to be relocated to neighbouring areas. However, in the late 1960s, the Yangtze River Planning Office (the predecessor of the Yangtze River Water Conservancy Planning Committee) decided to relocate settlements back to these diversion zones. Between the 1960’s and 1970’s, a large number of people settled in these diversion zones, and it is now very difficult to relocate them, according to Wang.
The China Monthly article also raises a big red flag about the Three Gorges Project eating up a major part of China’s investment in water projects and, concurrently, depleting the funding for other important projects such as the repair of embankments and dykes.
According to Wang, during a Yangtze River flood control conference in 1980, the central government committed to a plan to bolster all the embankments and dykes along the river by the year 1990. However, a government investigation in 1990 found out that this task was not executed as planned. The state council then invoked a similar stipulation that the Jingjiang Dyke be bolstered and heightened by the end of 1997, but this too has not been followed through.
Jiujiang City in Jiangxi is another prime example of funding inadequacy. Being the worst hit area in this year’s flood with thousands killed, the city had failed earlier to obtain funding to strengthen its dykes. The local government, after the completion of the first phase of dyke maintenance in 1992, applied to the central government for 30 million yuan (US$3.61 million) to fund further improvements. Its request was turned down by the Ministry of Water Resources.
Wang says that the state government has concentrated its investment on the Three Gorges project which, indeed, has become costlier every year. The total investment was 57.1 billion yuan (US$6.88 billion) in 1991 when it was approved by the national congress. In May 1993, its cost had mushroomed to 90 billion yuan (US$10.84 billion). It now totals a whopping 250 billion yuan (US$30.12 billion).
Wang’s article prompted a spirited response from Yi Wen, a hydrologist currently living in Canada who also participated in the Three Gorges Project during the 1980’s. He dismisses Wang’s argument that the flood control capacity of the Three Gorges dam is insufficient to contain the flood of century. He argues that the Yangtze reservoir was never intended to store all the flood waters, but that it is structured to adjust the volume of runoff water in flood peaks. For example, if flood water runs at 60,000 m3/second, it might possibly threaten the Jingjiang Dyke near Wuhan. The Three Gorges reservoir could then move to reduce the flood water to 55,000 m3/second by containing 430 million cubic metres water a day. By doing so, it could lower the flood level at the Jingjiang Dyke by 1.25 metres. "In this year’s flood, a decrease of 0.01 metre would have meant a great difference between life and death," says Yi.
Where Yi is in agreement with Wang is in his view that greater efforts should be made to bolster embankments, restore wetland and lakes which have been reclaimed, and improve the forestation in the upper reaches of the Yangtze River.
Three Gorges Probe welcomes submissions. However, it is not a forum for political debate. Rather, Three Gorges Probe is dedicated to covering the scientific, technical, economic, social, and environmental ramifications of completing the Three Gorges Project, as well as the alternatives to the dam.
Publisher: Patricia Adams Executive Editor: Mu Lan ISSN 1481-0913
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