Shanghai sinking as water table shrinksgreenspun.com : LUSENET : Grassroots Information Coordination Center (GICC) : One Thread
JUL 29, 2000
Shanghai sinking as water table shrinks
The land under 46 Chinese cities is sinking because underground water is used to supply the growing population. Drought worsens things
SHANGHAI -- Shanghai is sinking. The land under the skyscrapers and 13 million people of this bustling metropolis is deflating like a giant air mattress, slowly settling as its water table collapses.
Chronically dry China has been guzzling underground water to supply a booming economy and growing population.
The result is that land under 46 cities is sinking, the government says. Areas around Beijing, the capital, have sunk by up to 35.5 cm over the past decade.
Although Chinese officials warn publicly about relying too heavily on wells, drought in recent years has complicated the situation.
As rivers dry up, cities and farms drill more wells. More than 100 cities in northern China are short of water, according to the official Xinhua news agency. Some reservoirs are dry.
Shanghai now uses rivers, slowing its annual descent to less than 1 cm. But after years of decline, even that threatens China's business capital, which is less than 3 m above the Huangpu River.
""If we didn't control this, the ground would collapse by 1 m every decade,'' Mr Liu Yi, senior geologist for the Shanghai Institute of Geological Survey, said. ""The damage would be unbelievable -- floods and wrecked buildings.''
Shanghai suffers from the legacy of long, severe bouts of ground subsidence.
The problem stems from its rapid 19th century growth. Shallow water tables that had supported a Chinese trading port were quickly strained supplying an ever-growing population.
A flood wall was built in the early 1990s because of concern that the Huangpu would overflow onto Sun Yat-sen Road, the eight-lane riverfront boulevard.
With Shanghainese flair, they filled the wall with shops. The water on the other side of that wall was higher than the ground where shoppers walked.
Shanghai is now trying to reverse the decline by recharging its underground reserves, pumping in 19.8 billion litres of water a year.
In some areas the ground has risen by as much as 11.4 cm, Mr Liu said. --AP.
-- Martin Thompson (email@example.com), July 28, 2000
This will start happening here as well. Florida and Georgia (2 fast-growing states) are exhausting their underground water supply at an alarming rate. Add to that the current draught, and this situation becomes even more likely.
-- K (firstname.lastname@example.org), July 29, 2000.