Dams and Earthquakes

China says troops rush to plug dangerous cracks in dam

(May 13, 2008) The Zipingpu dam has been left with dangerous cracks as a result of Monday’s deadly earthquake, AP reports.

Over 2000 Chinese soldiers are involved in the repair efforts to prevent a dam collapse that would swamp the nearby city of Duijiangyan, endangering its 600,000 residents.

The Zipingpu dam’s enormous reservoir has the capacity to hold 1.2 billions cubic metres of water and is among the most modern in China, reports the Times Online, but was built despite warnings it lay close to a major earthquake fault line.

There are also concerns over dams closer to the epicentre, AP reports.

“There are already serious problems with the Tulong Reservoir on the Min River. It may collapse,” said He Biao, the director of the Aba Disaster Relief headquarters in northern Sichuan province, reports AP.

“If that happens, it would affect several power plants below and be extremely dangerous,” he said.

The Three Gorges dam was unaffected by the quake, Xinhua reported earlier today.

http://news.yahoo.com/

http://www.timesonline.co.uk/

Chinese dams compromised by earthquake; authorities on alert

In the wake of China’s massive earthquake, and amidst the desperate recovery effort, Chinese authorities have still more to worry about as damage to existing dams becomes evident.

The Chinese-language China News Service reports that 17 dams are either cracked or leaking water because of the earthquake across four counties and districts, including Beipei, Dianjiang, Banan and Nanchuan in Chongqing (not in Sichuan province).

Xinhua also reports that cracks have also been found in the dam structures of two reservoirs in Suishui township of Anxian County (or An county) in Sichuan province, approximately 50 km away from the epicenter of yesterday’s earthquake.

The Sichuan provincial government have said that severe cracks have formed on the dam at the Zipingpu Hydropower Station. Located at the junction of Dujiangyan City and Wenchuan County on the upper Minjiang River, the dam’s power plant has collapsed. In operation since 2006, the whole installation is now out of commission.

Last year, Fan Xiao, a geologist at the Bureau of Geological Exploration and Exploitation of Mineral Resources in Sichuan province, estimated in a Chinese National Geographic article last year that more than one-third of China’s reservoirs are poorly constructed and described them as “time bombs waiting to explode in the event of a severe flood or other unexpected occurrence.”

An official survey by the Ministry of Water Resources in September 2007 corroborated the danger, saying that by the end of 2005, there were 6681 reservoirs in Sichuan, of which 798 are thought to be dangerous and poorly built. Should any of these have been damaged by Monday’s earthquake, they would now pose a real danger to downstream populations.

No damage to the Three Gorges dam has been reported.

China’s leading business magazine, Caijing Net, reports that the Ministry of Water Resources has just issued an urgent notice asking all levels of government and technical staff to:

1) Monitor all dams and reservoirs in the disaster-affected area and pay close attention to the dangerous and ill-built dams and reservoirs.

2) Take emergency measures if anything serious happens.

3) Empty or lower the water levels of the reservoirs in the affected area.

4) Monitor the weather because rainstorms will aggravate the situation with landslides, collapses and mud-rock flows.

Geologists are also warning that landslides and mud rock flow that generally occur during and after earthquakes, could also block river courses, triggering the flooding of fields and create further unpredictable conditions.

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