SPACE WIRE
Shanghai mulls building dam to ward off rising sea levels
SHANGHAI (AFP) Feb 09, 2004
Alarm over rising sea levels and subsidence in China's largest city Shanghai has prompted officials to consider building a dam on its main river, the Huangpu, state press reported Monday.

"Its main function is to prevent the downtown areas from being inundated with floods," the China Daily quoted Shen Guoping, an urban planning official, as saying.

"The draft scheme is generally set and been filed to the Ministry of Water Resources for approval," Shen said.

If the dam wins appproval, the 250 million dollar project located on the lower reaches of the Huangpu in the northern part of the city would take five to seven years to complete, the newspaper said.

Over the years the rising water levels of the Huangpu, blamed on rising sea levels due to global warming, and subsidence has resulted in the building of hundreds of kilometres (miles) of flood walls.

Since 2000, 20 millimetres (almost one inch) of the city's coastline has disappeared, with the rise totaling 60 millimetres (2.4 inches) since the 1970s.

At the same time subsidence caused by the over-pumping of ground water and the rapid construction of skyscrapers thrown up in response to the city's economic boom has averaged over 10 millimetres a year.

While the city of more than 16 million people is unlikely to slip below the waterline soon, it is sinking quickly enough to raise concerns that the gleaming skyscrapers of China's financial hub could be entirely submerged in 600 years, according to the Shanghai Daily.

Still, the problem is far less severe than during the 1960s, when Shanghai was sinking by more than 100 millimetres a year -- a rate that would have put the city below sea level by 1999 if it had not been stopped.

Once subsidence is detected, action can be taken by pumping water into underground reservoirs and prohibiting further construction in affected areas.

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