Feng Hao, of Chinadialogue, Long Di says that part of the China capital is sinking due to decades of groundwater extraction (overpumping). In the China arid north, the natural underground water supply fails to meet the needs of many cities. In Beijing, the country capital, groundwater is pumped up from aquifers deep underground. But over-extraction of water in this region has lowered pumping to the extent that subsidence is now an urgent problem, especially for the residents of Beijing whose water needs are growing the most. Subsidence is caused by the decline in pressure within the aquifer (that is, which collapses the structure of the rock leading to the subsidence of the rocks above, eventually reaching the surface, with possible growth-faults present that relieve the stresses. The can also impact the stability of highways and building structures, known elsewhere in the world, such as in and around Houston, Texas (see: http://bit.ly/2bIRzDn). In June, a Chinese-led study revealed that Beijing is dropping by 11 centimeters per year. The research, published in the peer-reviewed journal Remote Sensing, was based on a type of radar that records land elevation changes called InSAR. But in Beijing people care little for the loss of water beneath them, focusing more on the air pollution above ground. Long Di, a professor at Tsinghua University Institute of Hydrology and Water Resources in Beijing told Chinadialogue that it is time to pay attention. There is a range of things that can be done. Either increasing surface-water availability or reducing demand for groundwater, a solution that Houston, Texas has applied that has reversed declining pressure (expressed by water level decline within the aquifer). Increasing surface-water availability could include construction of surface-water reservoirs to supply water. Reducing demand for groundwater could mean reducing agriculture until the new sources of surface water becomes available.
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