Land subsidence is a problem in more than 70 Chinese cities, the China Geological Survey, a bureau of the Chinese Ministry of Land and Resources, said on Friday.
Shanghai suffers the worst land subsidence in the country.
The bureau has recently conducted a series of geological surveys on the Yangtze River Delta, a major economic engine of the nation.
The Delta, with Shanghai at its core, covers economically developed Jiangsu and Zhejiang Province.
According to the bureau, the metropolis has been recording land subsidence since 1921, at depths of up to 2.6 meters.
Another seriously affected area is the Suzhou-Wuxi-Changzhou city group in Jiangsu. About 5,700 sq. km of land, or half of the total area of the three cities, has subsided to some extent, with the deepest subsidence measuring 2.8 meters.
Tianjin, an economic center in northern China, has reported land subsidence of 3.1 meters. Other cities suffering from the problem include Taiyuan, capital city of north China's Shanxi Province, and Xi'an, capital of northwestern Shaanxi Province.
Inappropriate siphoning of underground water and poorly thought-out urban construction projects have contributed to land subsidence, said Lin Xueyu, an academician with the Chinese Academy of Sciences.
(Xinhua News Agency February 10, 2007)