Shanghai has sunk by nearly three meters over the past 80 years,
causing 14.5 billion yuan (US$1.7 billion) worth of damage,
according to a report issued by the Nanjing Geological Survey
Center. Sixteen provinces and regions and 46 major cities also
suffer from subsidence.
Researchers believe that excessive pumping of underground water
the primary cause of the problem.
The report, with contributions from the geological departments
of Jiangsu and Zhejiang provinces and Shanghai Municipality, shows
that land south of the Yangtze River has sunk by an average of more
than 20 centimeters over an area of almost 10,000 square
kilometers.
The most serious ground subsidence occurs in the urban districts
of Shanghai Municipality and Suzhou, Wuxi and Changzhou in east
China's Jiangsu
Province, and Jiaxing in Zhejiang
Province. Subsidence in these areas has reached as much as 2.6
meters.
Suzhou, Wuxi and Changzhou have lost 2.6 billion yuan (US$310
million) because of the problem, which affects both urban and rural
areas. It causes damage to buildings and problems such as flooding
on farmland.
Guo Kunyi, vice director of the Nanjing Geological Survey Center
and the person in charge of the report, said that underground water
should be pumped with restrictions. He says that replacing
underground water could prevent further subsidence.
The government should also invest in monitoring machines and
survey equipment, Guo added. Most evidence of problems underground
comes from cracks and subsidence. Timely checking of such evidence
and prompt response can prevent further subsidence before it is too
late.
The researchers worked nearly five years on the report, which
cost more than 40 million yuan (US$4.8 million) to complete.
(China Daily March 22, 2005)