Despite the city's vigorous efforts to control the ground
subsidence
problem, downtown
Shanghai is
still sinking, according to a report recently issued by the
municipal water authority.
Shanghai sunk 11.02 millimeters in 2000, and the figure is not
expected to see a radical reduction in the near future, the report
said.
The report presented to the municipal government was based on a
general survey of the city's water resources conducted by the water
authority over the past two years.
"The surface subsidence at the speed of 10 millimeters a year is
internationally allowable," said Ruan Renliang, director of the
Water Resources Management Division of Shanghai Water
Authority.
"We still face challenges to get it under control for effective
urban management and sustainable development of such a populous
metropolis," he said.
Due to excessive exploration of underground water, Shanghai
suffered a severe annual subsidence of 37.6 millimeters from 1921
to 1965.
The government since then has taken administrative actions to
mitigate the situation.
The water authority set limits on the yearly total amount of
underground water that could be used and fixed a water quota for
manufacturers.
Meanwhile, big water consumers such as steel factories are obliged
to re-pump a certain amount of tap water, in proportion to the
water they use, back into the underground.
The measures were effective but since 1998, the slowed subsidence
has gained momentum again. Due largely to the growing number of
high-rises being built and underground construction, subsidence hit
11.13 millimeters a year.
In
2001, Shanghai had 142 million cubic meters (5,015 million cubic
feet) of usable underground water, but actually only around 8,000
(282,517 cubic feet)-9,000(317,832 cubic feet) cubic meters of
water will be consumed.
Some 14 million cubic meters will be poured back into the
underground this year in an attempt to control the subsidence
speed.
"It takes time for the limiting of the water exploration to show
its effect in stopping the downtown area from sinking," Ruan
said.
Ruan assured the public that Shanghai is well equipped to control
the problem, and that plans for the construction of a strong
anti-flood wall will keep any threat to the city at bay.
(China
Daily November 13, 2001)