Friday, July 23, 2004

Beijing Sinking

Troubling environmental news out of China. The fact that cities are sinking is unsettling enough. That it's a result of "ground water levels receding" seems like a cause for even more serious alarm. The good news? It makes it that much easier for anyone digging a hole to China.

Chinese cities, including Olympic host Beijing, slowly sinking

BEIJING (AFP) - Cities across China are sinking, including the capital Beijing which has set up a warning system that state media said would act as an alert to ensure Olympics venues are not affected.

According to vice Beijing mayor Lu Hao, subsidence poses "a major threat" to the host of the 2008 Games, where infrastructure is being built at a rapid rate.

To date, more than 1,800 square kilometres in Beijing have been hit, with about 50 places destroyed, including factories, buildings and ground pipelines, said Wei Lianwei, director of Beijing Institute of Geological Survey.

The biggest drop was 722 millimetres (28.8 inches), the China Daily reported.

It cited one incident in 1998 where a crack caused by sinking ground forced a rubber factory in the capital's Shunyi district to stop production.

The crack is now about 800 metres wide (2,640 feet) and 25 kilometres (15.5 miles) long.

Experts cited by the newspaper said it would eventually threaten the safety of the nearby Beijing Capital International Airport, where a 2.3 billion dollar expansion project is underway in preparation for the Olympics.

To counter the threat a warning system was set up Thursday in Beijing to monitor, research and control ground sinking.

The paper said its purpose was "to ensure security for the city and the 2008 Olympic Games". A geological survey has also been launched.

Statistics show that about 50 cities in China covering 48,655 square kilometres (19,462 square miles) have sunk, causing millions of dollars in damage.

Earth or ground sinking is caused by ground water levels receding.

Excessive pumping of ground water, exploration of geothermal resources and large-scale construction are all contributing factors, said Zhang Hongtao, deputy director of China Geological Survey Bureau.

It is not just Beijing that suffers. Shanghai, Tianjin and Taiyuan are the the worst hit in China with each sinking more than two metres (6.6 feet) since the early 1900s, the newspaper cited Zhang as saying.

To counter the problem in Shanghai, the local government last year ordered a curb on the number of high-rise buildings which are partially blamed for the problem.

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