Why China’s Largest Cities are Sinking
China faces many resource and environmental challenges from its rapid growth. One of the most important is its water problems, with the vast water consumption needs of its cities and the imbalance between the dry north and wet south.
in the provinces of Hebei, Shandong, Henan, and Shanxi, groundwater accounts for 70% of the total water supply; this increases to more than 90% for the Beijing and Tianjing.
The extraction of groundwater supplies has created major problems in most of China’s largest cities. The scale of extraction has been such that for coastal cities, such as Tianjin, Hebei and Shandong, and Shanghai, there has been major saline intrusion. This is a serious issue which in some countries has led to contamination of fresh groundwater and even an inability to water crops.
But there is an even more fundamental problem caused, to the very stability of the ground on which cities stand.
Significant subsidence, of over 2m, has been found in at least 50 cities.
The greatest problems are in the Delta region of the Yangtze River, the Northern-China Plain and the Fen-Wei River graben, all areas of rapid urbanisation.
Clearly such a significant drop in levels will create problems of subsidence. Due to the variable thicknesses of superficial geological deposits, subsidence can be highly variable which giving rise to cracking of the ground and differential settlement problems. This causes significant damage to buildings and utilities. READ MORE