Completed in 2006, the highly controversial dam/reservoir at Zipingpu is a massive 50 story hydroelectic facility built just 7km upsteam from the ancient Dujiangyan Irrigation System, which has protected the Chengdu plain from the Min River since 256 BC.
The dam itself is located only 20km (12 miles) from the epicenter of the earthquake. If it were to breach, it would spell disaster for the already heavily damaged city of Dujiangyan and it's irrigation system, which in turn forks water to the major city of Chengdu downsteam. The cascade effect would "swamp" (i.e. wall of water) the entire basin, making the Johnstown flood look like a walk in the park.
Here is a file photo of a view from above the dam looking down towards the basin:
And a zoomable Google Satellite Map with the epicenter marked by a green arrow:
The dam is located just to the right of the green arrow if you zoom in.
Sky News article with a bit more detail:
http://news.sky.com/skynews/article/0,,30200-1315944,00.html
Quake Town Threatened By Cracking Dam
Updated:16:19, Wednesday May 14, 2008
Chinese troops have rushed to plug “extremely dangerous” cracks in a dam wall, upriver from the earthquake-devastated town of Dujiangyan.
The state-run news agency Xinhua said that 2,000 troops had been sent to work on the Zipingku Dam in Sichuan province.
Speaking from Dujiangyan, Sky’s China correspondent Peter Sharp said many local people seemed unaware of the threat.
“It (the dam) is only five kilometres away, we are downstream of it,” he said.
“We understand that some of the People’s Liberation Army troops that are deployed here helping with the rescue operation... 2,000 of them [have been moved] upriver to seal some serious cracks in the dam wall.”
In a separate report, Xinhua said Dujiangyan would be “swamped” if there was major problems at the dam.
It reported that the water resources ministry had set-up an emergency command centre at the dam “to discharge the reservoir’s rising waters and guarantee that the damage posed no threat to Dujiangyan and the neighbouring Chengdu Plain.”
That dam is holding back over a billion m3 of freezing cold water. Which is another way of saying a billion tonnes of water. Or one tonne for everyone in China.
Can someone tell me what a couple of thousand unskilled troops are going to do to a 50 story dam that is cracked?
This thing is 500 feet tall, there isn’t enough chewing gum or silicone tubes for 2000 men to have any effect at all. Drain the lake and then pressure fill the crack, pouring another thick face on the lake side of the thing for support.
It will take years to properly repair this dam, assuming there isn’t an aftershock before it’s done.
Zipingpu also describes what people downstream from the dam are doing about now.
Just dam.
I'll admit up front: My knowledge of geology and plate tectonics doesn't go beyond high-school level. Having said that, when I first read about Three Gorges several years ago, my first thought was "earthquake." China is a country that is no stranger to large quakes. The weight of the waterpool created by the dam must be staggering. I have to wonder if that weight is enough to stress the plates into movement.
got any of that sticky crap goo left over?
“China says troops rush to plug dangerous cracks in dam...”
Won’t their bodies get blown out of the cracks as the water level continues to rise behind the dam and the pressure grows greater and greater?
I’ve got a really bad feeling about this.
ping
Do they plan on using the soldiers, or just have them chew a lot of gum?