China’s Ministry of Water Resources has dispatched teams to Sichuan, Chongqing, Yunnan, Gansu and Shaanxi provinces to prevent dams that were damaged by the devastating earthquake from bursting and endangering the lives of residents. Several dams are believed to be imminently threatened in the key region where the Tibetan plateau meets the Sichuan plain.
One of the worst-damaged cities is Dujiangyan, site of multiple dams and weirs that irrigate some 3 million hectares. The Dujiangyan irrigation works date from the third century BC, when engineers split the Min river where it falls from the mountains, and diverted it to irrigation channels along the plain.
“Upstream on the Min river is an important reservoir called Tulong which is already imperilled,” He Biao, deputy party chief of Aba prefecture, told reporters. “If the danger intensifies, this could affect some power stations downstream.”
The quake caused the 760-megawatt hydropower station at Zipingpu, nine kilometers upstream of Dujiangyan, to collapse. It began operations in 2006, as part of China’s program to develop its poorer western regions.
Water is being released at 50% above average levels to relieve pressure on the cracked dam, the Ministry of Water Resources said on its Web site. “If Zipingpu develops a serious safety problem, it could bring disaster to Dujiangyan city downstream,” where half a million people live, the ministry said.
Experts from China’s earthquake bureau raised concerns about the Zipingpu dam’s location near a fault zone before it was built in 2000, according to Aviva Imhof, the China program director for the International Rivers Network, a group that opposed construction of the plant. She cited leaked transcripts of a September 2000 meeting about the issue.
The flow of the Jialing River has been blocked by landslides in Huixian county, in southeastern Gansu’s Longnan region, with rubble holding back 600,000 cubic meters of water.
Cracks on the famous Yuzui or “fish mouth” levee further downstream, the crux of the Dujiangyan irrigation system, are not serious, the ministry says. The massive Three Gorges Dam, hundreds of kilometers down the Yangtze River from the epicenter, was not affected by the quake, officials with the China Three Gorges Project Corporation said. (IHT, May 15; Reuters, May 14)