Major project for Xinjiang province amid concerns over future water supply
Jonathan Watts, guardian.co.uk 2 Mar 09;
China is planning to build 59 reservoirs to collect water from its shrinking glaciers as the cost of climate change hits home in the world's most populous country.
The far western province of Xinjiang, home to many of the planet's highest peaks and widest ice fields, will carry out the 10-year engineering project, which aims to catch and store glacier run-off that might otherwise trickle away into the desert.
Behind the measure is a concern that millions of people in the region will run out of water once the glaciers in the Tian, Kunlun and Altai mountains disappear.
Anxiety has risen along with temperatures that are rapidly diminishing the ice fields. The 3,800-metre Urumqi No1 glacier, the first to be measured in China, has lost more than 20% of its volume since 1962, according to the Cold and Arid Regions Environmental and Engineering Research Institute (Careeri) in Lanzhou.
To deal with the consequences, Xinjiang will set aside 200m yuan (£20m) for each of the next three years. In the first phase, 29 reservoirs will be built with a combined capacity of 21.8 billion cubic metres of water, according to the Xinhua news agency.
Wang Shijiang, director of Xinjiang's water resource department, said the mountain reservoir system was designed to "intercept" meltwater, which has increased in volume over the past 20 years as a result of global warming.
Xinjiang is particularly dependent on a steady supply of meltwater from glaciers, which act as solid reservoirs that store precipitation in the winter and release it in the summer.
Few city residents understand the problem because in recent years water supplies have surged thanks to the extra meltwater and increased rainfall. The excess supply has been used to water golf courses and make artificial snow for a ski slope in semi-desert Urumqi. But scientists say the glut is unsustainable because it comes from the release of water that has built up over thousands of years.
"At the moment there is plenty of water in the big cities. But it is hard to say how long it will last," said He Yuanqing, a glaciologist at Careeri. "On one hand, global warming is accelerating the melt. But on the other, it is increasing rainfall, so we need a way to store the extra water."
It is unclear, however, how long the water can be stored without replenishment. Experts have previously called for the reservoirs to be built underground so that the water does not evaporate in the summer, when Xinjiang has the highest average temperatures in China.
Overexploitation of river systems and oases has exacerbated the problem. The volume of water in the once vast Aibi lake in Xinjiang has decreased by two-thirds over the past 50 years, the Beijing News reported today.
In terms of glacier melt, the worst affected area in China is the Tibetan plateau, often described as "the roof of the world". Last month, Chinese scientists warned that glaciers on the plateau had lost 989 million cubic metres over the past 40 years and were continuing to melt at a "worrying speed". They added that ice fields had shrunk by 196 sq kilometres, equivalent to a quarter of New York city.
