Beijing faces water shortage and land subsidence
The 800 water extraction wells within the fifth ring road areas in Beijing will be closed this year as part of an effort to conserve underground water. Underground water extraction will be halted by 2014 in the urban areas of Beijing as authorities seek to prevent further land subsidence, or sinking in the city. Beijing has more than 10,000 water extraction wells in the urban and suburban areas. The wells in the suburban areas could be preserved, but the authority will make sure that no more water extraction wells will be opened in future. Last year’s total water demand in Beijing was 3.6 bilion cubic meters.
Capturing and using large amounts of surface water, along with the pumping of a lot of groundwater, means groundwater reserves have depleted, as has their ability to be replenished – and that means groundwater levels drop.
Land subsidence
Statistics provided by the authority show that the past 10 years have seen the water table of the capital dropping from 12 meters to 24 meters due to overextraction of underground water, which is a major factor causing land subsidence in Beijing according to authority official statistics. Authorities have established seven monitoring stations and 117 GPS monitoring points as part of an early warning system due land subsidence. According to a report conducted by Beijing Institute of Hydrogeology and Engineering Geology in 2010, land subsidence in Beijing has speed 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 mms every year. Land subsidence in certain areas of Changping district and Chaoyang district has exceeded 900 mms in total. Numerous cases of fracturing of water and gas pipes and road sinking occurred at land subsidence areas in recent years, the report said. It warned of a potential threat to the construction of new subway lines posed by subsidence. Land subsidence has plagued more than 50 cities in China, such as those in the Yangtze River Delta and North China. Shanghai is among the most severely affected cities.
Rising underground water
Experts also warned of the possible side effects of a rising underground water level. Rising underground water could also cause potential damage because the ground level will rise eventually. There might be water in the subway tunnels on land that used to be dry and the underground pipes could also be threatened according to some water experts. The State Council approved a national set of guidelines to prevent land subsidence during the 2011-20 period, which include a nationwide survey on land subsidence, the establishment of monitoring networks in affected areas and increased control over underground water-pumping.
The North-South Water Diversion Project
The North-South Water Diversion Project will bring 1 billion cubic meters of water supply to Beijing in 2014. The water could satisfy one-third of the total water demand in Beijing. The water diversion project is designed to take water from China’s longest river, the Yangtze River, to feed the drought-prone areas in the north, including Beijing and Tianjin. The water from the diversion project would also help to cut underground water extraction in the capital by half, as underground water now accounts for two-thirds of the water supply in Beijing. The transfer project will relieve Beijing’s water shortage for quite some time into the future, and there’ll be no risk of ‘drought’, but it’s not a permanent solution.
Figurеs from thе Statе Council’s South-North Watеr Transfеr Projеct Officе show that, of the 155 individual work items involved in the first stage of the projеct’s еast and central routеs, 33 (or 21%) have been complеtеd, whilе 67 (43%) arе undеr construction. China has about 20% of the world’s population, but only 7% of its water resources to sustain it. Only 14.7% of the country’s water is distributed in the vast areas to the north of the Yangtze River, where the amount of arable land accounts for 59.2% of the national total, and the population makes up 44.4% of the total. The population of China’s capital has doubled since 1980, and, though agricultural and industrial water use is down, municipal use is up.
Beijing’s Water Crisis (1949 — 2008 Olympics)
Featured image: Beijing Tonghui Flyover (Credit: OVM)
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