A crisis is developing beneath China’s farms and cities. With about 20% of the world’s popula-tion but only about 5-7% of global freshwater resources, China draws heavily on ground¬water. Those reserves are being depleted at an alarming rate in some regions and are badly polluted in many others.
The water crisis is not unique to China, but the problem here is orders of magnitude bigger than anywhere else:’
Groundwater is used to irrigate more than 40% of China’s farmland, and for about 70% of the drinking water in the dry northern and north¬western regions.
During the past few decades groundwater extraction has increased by about 2.5 billion cubic metres per year. Groundwater levels of the arid North China Plain have dropped as fast as 1 metre a year between 1974 and 2000, forcing people to dig hundreds of metres to access fresh water.
Water is scarce for two-thirds of China’s 660 cities. As China’s economy expands, so will its demand for water. The country will consume 750 billion cubic metres of water a year by 2030, about 90% of the total amount of usable water resources in the country..
Pollution is also putting the system under pressure. In southern and southeastern China, which have seen rapid economic development, groundwater is now laden with heavy metals and other pollutants. 90% of groundwater is polluted, 60% of it seriously so.
The government hopes that a massive system of canals and pipes, to funnel 45 billion cubic metres of water a year from China’s moist south to its arid north, will alleviate groundwater depletion once it is completed in 2050.
Climate contributed only about 10-30% of the water-table depletion in three regions of China. The majority of the depletion was down to farming practice: “There is much room for improvement in terms of more effective water management.
Arguably, the biggest improvement could come in the agriculture sector, which already uses 70% of the Country’S fresh water. To boost grain production, for example, China has a double-cropping system of growing wheat in winter and maize in summer. But because there is very little precipitation on the North China Plain in winter, this draws deeply on groundwater supplies. The country could import grain, and synchronize crop production with the climate by ending the cultivation of winter wheat and growing maize for more of the year.
Qiu 2010 China faces up to groundwater crisis nature vol 466 p 308
- Martin Eastwood