April 26, 2000
Reservoir Level Should Be Kept Low to Reduce Resettlement and Navigation Problems, Experts Warn
A group of senior engineers, water management experts, and academics, have made an urgent appeal to China’s leaders to rethink the plans to fill the Three Gorges dam’s reservoir to capacity by 2009.
In a petition submitted last month, 53 experts warned that filling the reservoir to 175 metres could have dire consequences for navigation along the Yangtze river and hundreds of thousands of people living in the Three Gorges area.
The original plan, approved by the National People’s Congress in 1992, was to keep water levels behind the Three Gorges dam at 156 metres for the first ten years of operation, in order to allow time for resettlement and to evaluate the impact of silt deposits on navigation and ports at the reservoir’s uppermost end. If feasible, then the water level would be raised to a final operating level of 175 metres between the dam’s 17th and 20th year of operation. But in 1997, dam officials changed the plans: the water level is now scheduled to rise to 175 metres in the sixth year of operation, 2009, in order to maximize the dam’s power output.
The petition, written by Lu Qinkan*, a leading hydrologist who worked on the dam’s original feasibility study, calls for a return to the original plan so that experts will have the time they need to monitor silt buildup and to determine if higher water levels are viable. This would also provide some relief for resettlement authorities, the experts argue, who are faced with the costly and difficult task of moving more than one million people out of the Three Gorges region.
Filling the reservoir to the maximum 175 metres will displace an estimated 1.13 million people and raise the Yangtze river more than 10 metres at Chongqing city, submerging drainage outlets and backing up the city’s sewage. At the 175-metre water level, more silt is expected to be deposited as well, blocking shipping traffic along the Yangtze and raising water levels even higher during the first twenty years of operation, which could force an additional 300,000 people to leave their homes.
According to the Beijing Water Institute, a government research agency that conducts hydrological studies, the two largest ports in Chongqing would become choked with silt if a 1954 flood were to occur while the Three Gorges reservoir was at 175 metres.
When the Gezhouba dam was under construction on the Yangtze in the early 1970s, Premier Zhou Enlai warned: “this is an important river and there can be nothing wrong with it. If the shipping is blocked, the dam will have to be dismantled, and that is a serious crime. . .chopping off the heads of those responsible would not be enough.”
Dam officials have proposed building more dams on Yangtze tributaries flowing into the Three Gorges reservoir to reduce the inflow and build up of silt by about half. But the experts write in their petition that the proposed Xiluodu and Xiang Jiaba dams on the upper Jinsha river will have no effect on the larger sands expected to deposit at the reservoir’s upper end.
Lessons from the Sanmenxia Dam on the Yellow River should be learned, the experts warn. Completed in 1960, the multi-purpose Sanmenxia dam is useless for controlling floods and produces one-third of its expected power output due to massive silt buildup in the dam’s reservoir. Scientists advised dam officials in the 1950s to keep water levels low and use bottom outlets in the dam for flushing out silt. But the dam builders paid no attention. Shortly after the dam was built, silt deposits raised the river bed by five metres in places, threatening to flood the city of Xian 100 kilometres upstream. To avert a flood disaster upstream, former Premier Zhou Enlai ordered the dam rebuilt. But even with bottom outlets built into the new dam structure and operating levels kept low, silt buildup remains a problem upstream.
Keeping the Three Gorges reservoir at 156 metres would keep Chongqing harbour and the mouth of Jialing river – a Yangtze tributary that flows through Chongqing – silt-free. It would eliminate drainage and sewage problems arising from high water levels in the reservoir. It would reduce the number of people who have to be moved by an estimated 520,000 people. It would also mean fewer landslides, fewer cultural and historical sites drowned, and fewer environmental disruptions caused by resettlement.
“We appeal to the central authorities to pay close attention to these issues,” the experts conclude. Similar appeals were sent by a group of 24 experts in March 1998 and March 1999, urging the government to respect the NPC-approved plan. “It is very regrettable,” the petitioners write, “that no reply was given. . .The success or failure of the Three Gorges project is crucial to our national interest.”
Dated March 3, 2000, the petition was addressed to Premier Zhu Rongji, President Jiang Zemin, National People’s Congress Chairman Li Peng, and Li Ruihuan, Chairman of the Chinese People’s Political Consultative Conference (CPPCC).
About one-third of the signatories are former members of the CPPCC which advised the State Council not to proceed with the Three Gorges dam in the late 1980s. The signatories include:
Lei Shuxuan, a former advisor to the Ministry of Electric Power Ye Yongyi, an advisor to China’s Water and Hydropower Institute and former head of the Three Gorges project feasibility study hydrology group Qian Rutai, former engineering director at the Yellow River Sanmenxia Dam Engineering Bureau Zhou Qixiang, former deputy chief engineer for Nanjing Port
* Lu Qinkan is one of nine specialists who refused to sign on to the final assessment of the Three Gorges project in 1988. Lu contributed an essay, “Ten Controversial Issues on the Three Gorges Project,” for the original Chinese edition of Yangtze! Yangtze! which was banned in China in 1989.
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