2010年8月20日
Image: Soil erosion in China / Xi-Ping Deng and Bing-Cheng Xu
Scientists are calling the landslide that hit Zhouqu, in Gansu province, on 8 August the most devastating in China’s history. But worse could come if global warming and government inaction continue.
The landslide was triggered by extraordinary rainfall over the summer — measuring 97 mm for one 40 minute period in parts of Gansu in the run up to the Zhouqu disaster. The flowing mud covered a five kilometre by 300 metre wide swathe of Zhouqu with 5 metres of mud. As of Wednesday afternoon, the death toll was 1,287 people and 457 missing were still missing.
Xi-Ping Deng, a soil erosion and dry land farming specialist at the Institute of Soil and Water Conservation of the Chinese Academy of Sciences in Yangling, Shaanxi says that China has been hit by some 15 major landslides this year and that many more areas are ripe for landslides in the future. Deng, and his colleague and Bing-Cheng Xu also at the Institute of Soil and Water Conservation, have compiled a map showing areas of China facing different degrees of soil erosion. The figure, based on data from a 2006-2008 government –sponsored survey of soil erosion and on data from other sources, indicates five of the most recent deadly landslides this year.
Deng says land degradation, through deforestation and farming, is partly to blame. The degraded land is more likely to be swept away by wind or water. But global warming is exacerbating the situation by creating more extreme weather patterns. Erosion usually happens in storms, says Deng. The southeast, usually hit by the heaviest rains, is the most greatly eroded, but as the Zhouqu disaster shows more arid regions are also in danger.
It is possible to counter landslides by conservation efforts aimed, for example, at introducing vegetation and to soften their impact through monitoring systems that would alert people to danger. Deng says the wealthier cities and towns on the eastern coast generally have such measures in place. But of an estimated 600 cities and towns throughout China that are threatened by landslides, Deng says that only 200 have enough money for proper measures.
Deng is hopeful that signs of attention to the problem, such as Premier Wen Jiabao’s visit to the area, will translate into concrete measures.
Meanwhile, state media reports that the situation is getting better, and officials, such as Minister of Civil Affairs Li Liguo, have been quick to call relief supply measures adequate. Reports quoting officials from the local government, however, are less optimistic. (Nature) |
