75 million people live downstream of the Three Gorges Dam in China.

Dam Safety Analysis
Chapter Ten

"For the Three Gorges design, a 6.5 magnitude earthquake occurring
on a fault 17 kilometres away is used for structural analysis."
http://www.threegorgesprobe.org/pi/documents/three_gorges/damming3g/c...

Quake in China Kills Thousands
7.9-Magnitude Temblor, Centered in Sichuan, Is Country's Worst in Decadeshttp://www.washingtonpost.com/wp-dyn/content/article/2008/05/12/AR200...

Scientific American article from a couple of months ago.

March 25, 2008
China's Three Gorges Dam: An Environmental Catastrophe?

"Surveys show that the Three Gorges region may be next.
Chinese Academy of Engineering scholar Li Wangping
reports on the CTGPC's Web site that the area registered
822 tremors in the seven months after the September 2006
reservoir-level increase. So far, none have been severe
enough to cause serious damage. But by 2009, the dam's
water level is set to be raised to its full 575-foot capacity
and then lowered about 100 feet (30 meters) during flood
season. That increase in water pressure, in water fluctuation
and in land covered by the reservoir, Fan says, makes
for a "very large possibility" that the situation will worsen"http://www.sciam.com/article.cfm?id=chinas-three-gorges-dam-disaster

Reservoir-induced Seismicity in China (pdf)
LINYUE CHEN1 and PRADEEP TALWANI1

Abstract-A review of case histories of reservoir-induced seismicity (RIS)
in China shows that it mainly occurs in granitic and karst terranes.
Seismicity in granitic terranes is mainly associated with pore
pressure diffusion whereas in karst terranes the chemical effect of water
appears to play a major role in triggering RIS. In view of the characteristic
features of RIS in China, we can expect moderate earthquakes to be induced
by the construction of the Three Gorges Project on the Yangtze River.http://scsn.seis.sc.edu/Publications/pageoph98/pageoph98.pdf

A major dam burst at the Three Gorges could be one
of the deadliest natural disasters in recorded history.

s

You might like to see the article today 14th May in The Independent.

The Three Gorges seems to be ok this time but others aren't.

"Thousands of troops are tonight fighting to plug dangerous cracks in a dam
above an earthquake-hit Chinese town.


Zipingpu Reservoir is upstream from Dujiangyan which was near the epicentre of
the 7.9-magnitude quake.

China's top economic planning body said today that the earthquake had damaged
391 dams. It said two of the dams were large and 28 were medium-sized.

The official Xinhua news agency said the ministry had set up an emergency
command centre at the dam.

The death toll from the quake may already by more than
50,000".................

Further down

.......................

"Sichuan had other major dam projects, including the massive Three Gorges dam,
the world's largest about 350 miles to the east of the epicentre, but
officials said it escaped undamaged.

He Biao, the director of the Aba Disaster Relief headquarters in northern
Sichuan, said there were also concerns over dams closer to the epicentre.

"Currently, the most dangerous problems are several reservoirs near Wenchuan,"
he said.

"There are already serious problems with the Tulong Reservoir on the Min
River. It may collapse. If that happens, it would affect several power plants
below and be extremely dangerous," he said."


http://www.independent.co.uk/news/world/asia/creaking-dam-adds-to-earthquake-survivors-fears-828088.html

Skeats

"Skeats" <notmeeit... at (no spam) blueyonder.co.uk> wrote in message

news:y1GWj.3516$DZ6.159 at (no spam) text.news.virginmedia.com...







You  might like to see the article today 14th May in The Independent.

The Three Gorges seems to be ok this time but others aren't.

"Thousands of troops are tonight fighting to plug dangerous cracks in a dam
above an earthquake-hit Chinese town.

Zipingpu Reservoir is upstream from Dujiangyan which was near the epicentre of
the 7.9-magnitude quake.

China's top economic planning body said today that the earthquake had damaged
391 dams. It said two of the dams were large and 28 were medium-sized.

The official Xinhua news agency said the ministry had set up an emergency
command centre at the dam.

The death toll from the quake may already by more than
50,000".................

Further down

.......................

"Sichuan had other major dam projects, including the massive Three Gorges dam,
the world's largest about 350 miles to the east of the epicentre, but
officials said it escaped undamaged.

He Biao, the director of the Aba Disaster Relief headquarters in northern
Sichuan, said there were also concerns over dams closer to the epicentre..

"Currently, the most dangerous problems are several reservoirs near Wenchuan,"
he said.

"There are already serious problems with the Tulong Reservoir on the Min
River. It may collapse. If that happens, it would affect several power plants
below and be extremely dangerous," he said."

http://www.independent.co.uk/news/world/asia/creaking-dam-adds-to-ear...

Skeats

And on the link below, I didn't point out how much
the Chinese have underestimated the risks  at the
Three Gorges. Pretty much at every step they seemed
to have low-balled the problem. When I see that kind
of bias combined with such potential for disaster, it
gives me the willies.

"Examples of the flaws in CYJV's analysis are as follows:"

Underestimation of earthquake ground accelerations

Inadequate analysis of reservoir-induced seismicity

Inadequate analysis of structural stability

Underestimation of the risks caused by catastrophic landslides

Underestimation of risk of spillway failure

Failure to consider downstream effects of cofferdam failure

No provision for decommissioning of the dam

Flawed Bases of CYJV's Sedimentation Analysis
 Unreliable Equilibrium Slope Calculation

Miscalculation of Bed Load

Inadequate Empirical Estimate of Reservoir Trap Efficiency

Underestimation of Reservoir Sedimentation Rates

http://www.threegorgesprobe.org/pi/documents/three_gorges/damming3g/c...



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