Why China’s Largest Cities are Sinking Posted by
andrew lainton 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.
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