So serious has the depletion of China’s groundwater become as a result of industrialization and urbanization that the country’s large cities are sinking, as, potentially, are the high-speed rail corridors between them. So concerning is that to authorities that the State Council has made areas with high-speed rail links a priority in a new land subsidence research project it has approved to be completed by 2015. In the order of these things, that is a crash deadline.
The survey is one of four projects that the Ministry of Land and Resources said this week that the State Council had ratified to combat the effects of China’s growing water shortage. Others include yet more controls on pumping underground water, and the setting up of monitoring networks in the worst affected areas–the Yangtze river delta, the North China Plain and the Fen and Hua river basins. The network is to be in place by 2020.
It didn’t take any technology to see the 8 meter crack that opened up earlier this month in a road near the Shanghai World Financial Center. (There are some pictures here.) That is despite authorities taking preventive measures since 2005 to combat ground subsidence caused by falling water tables. Municipal officials say the city is still sinking by seven millimeters a year. That is a better state of affairs than in the past, however. Shanghai used to be sinking by several centimeters a year.
A third of China’s water reserves lie in underground aquifers. They supply 70% of the country’s drinking water and 40% of its farm irrigation needs. They are being stretched to their limits, particularly across the grain belt of the North China Plain as evermore wells are sunk to draw water for city dwellers and industry. Underground water pollution is a separate concern, but as serious.
Shanghai is one of more than 50 large cities with a similar Venice-like problem of subsidence because the water table below it is sinking. Beijing, Tianjin, Hangzhou and Xian are among others. As the number of 50 cities has been quoted since at least 2006, we suspect it may undercount the problem today. In a paper the China Geological Survey published that year the direct economic cost of subsidence was put at 1 billion yuan ($160 million) a year. It will likely top that now.
Tianjin, which like Shanghai has been sinking since the 1920s although it wasn’t until the 1960s that it was understood why, shows why widespread limits on groundwater pumping are so urgent, and also how difficult it is to control subsidence. The city introduced restrictions as long ago as 1985. Its sinking has slowed from 80 millimeters a year then but is still dropping 20 millimeters a year now. Coastal cities share another characteristic with Venice. Floods are becoming more frequent and severe. The lower cities sink the more susceptible they are to them.
We have noted before the potential explosive social costs of a water crisis getting beyond the government’s control. It will take a comprehensive program of water conservation, better water resource management and better husbandry of the ecosystem. And there are plans on all those fronts. But if they fail, it will be more than a high-speed train or two that comes off the rails.