Wells.jpg (Photo : SCMP)
Beijing will gradually be shutting down some 6,900 urban wells in the next five years to protect groundwater and improve drinking water quality, reported Shanghai Daily.
The shutdown operation will have to be carried out gradually because the wells currently still provide 240 million cubic meters of water annually, which according to Zhang Ping, deputy head of the Beijing water authority, accounts for about one-fourth of Beijing's total urban water supply.
The middle route of the North-South Water Diversion Project will soon come on-stream, bringing 1 billion cubic meters to Beijing each year from a reservoir on the Hanjiang River, enough to satisfy about one-third of the city's total water demand, and making closure of the wells feasible.
The closure of the water extraction wells is part of an integrated effort to conserve underground water. Statistics at Beijing's water authority show that during the past 10 years, the water table of the capital dropped from 12 meters to 24 meters due to over-extraction of underground water, which is a major factor causing land subsidence in Beijing.
According to a 2010 report by the Beijing Institute of Hydrogeology and Engineering Geology, land subsidence in the region has sped up since the 1950s due to the large amount of groundwater extraction.
As of 2009, the area with the highest record of ground subsidence reached 137.51 millimeters every year. In fact, the city authorities have already established seven monitoring stations with 117 GPS monitoring points as part of an early warning system as protection for the city residents. Numerous cases of fracturing of water and gas pipes and road sinking have been witnessed at land subsidence areas in recent years.
Aside from conserving groundwater, the urban wells have to be shut down because they are already old and some of them may have already been neglected.
As Zhang said, aging of facilities and poor management mean that the quality of water from wells cannot be guaranteed in some areas, resulting in a steady stream of complaints from citizens.
