China: Sichuan quake imperils hydro-dams

Submitted by WW4 Report on Thu, 05/15/2008 - 21:46

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)

See our last posts on China and regional struggles for control of water.

Sichuan's paradox

Submitted by Bill Weinberg on Fri, 05/16/2008 - 21:26

From a May 15 New York Times op-ed by Simon Winchester, "Historical Tremors." We aren't sure what the point is other than to gloat, but it does include some interesting background:

IT is a cruel and poignant certainty that the children who died in the wreckage of their school during the earthquake this week in Dujiangyan, China, knew all too well that their country once led the world in the knowledge of the planet's seismicity.

They would have been taught, and proudly, that almost 2,000 years ago an astronomer named Chang Heng invented the world’s first seismoscope. It was a bizarrely imagined creation, with its centerpiece a large bronze vessel surrounded by eight dragons, each holding a sphere in its mouth.

A complex system of internal levers ensured that if an earthquake ever disturbed the vessel, a ball would drop from a dragon’s care into the mouth of a bronze frog positioned underneath. By observing which dragon had dropped its ball, Chang Heng could ascertain the location of the quake. And always, as the emperor for whom Chang Heng fashioned the device noted, the earthquakes came from the mountains in the west, where Dujiangyan lies...

And yet, in the 16th century China’s innovative energies inexplicably withered away, and modern science became the virtual monopoly of the West. There had been any number of Chinese Euclids and Archimedes but there was never to be a Chinese Newton or Galileo. The realm fell steadily behind, century by century; it became impoverished, backward and prey to the caprices of nature.

There is a peculiar paradox in the Sichuan disaster. Dujiangyan is known across the nation as the site of one of China's greatest ancient wonders. In 256 B.C. an engineer named Li Bing, concerned about the catastrophic annual flooding of the Min River, completed a huge water diversion and irrigation scheme. It involved cutting a long trench through a granite mountainside — achieved by the patient process of burning grass bonfires on top of the rocks and pouring cold water until the granite cracked. It took decades, but Li Bing’s 2,300-year-old project still stands less than a mile from the town’s ruined school, and it still works.

And yet, did the Chinese continue with their early expertise in flood prevention? Just as with Chang Heng's seismic mastery, Li Bing's expertise counted for nothing; year upon year, thousands of Chinese die in immense inundations in the great rivers that course across the country; some 400 dams sustained damage in this week's quake.