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Human error in overusing natural resources  

2011-01-09 11:15:00|  分类: 环保呐喊 |  标签: |举报 |字号 订阅

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Human error in overusing natural resources

Jiang Gaoming

January 07, 2011 published in Chinadialogue

        Last year’s deadly mudslide at Zhouqu offers compelling lessons on the ability of human development to increase the risk of natural disasters, writes Jiang Gaoming. “China endured 26,000 geological disasters from January to July last year, nearly four times as many as the same period in 2009.”

        2010 was another bad year for China in terms of natural disasters: severe drought in the south-west was followed by floods on the upper Yangtze. Then came the mudslide in Zhouqu and then more flooding, this time in the country’s north-east. Extreme weather played a central role in this series of tragedies, of course. But the ability of humans to increase the risk and impact of such crises should not be overlooked. The mudslide in Zhouqu – and the area’s recent development history – offers a powerful example.

        Zhouqu county, in China’s north-western province of Gansu, was once known for its forests, rich water resources, fertile land and pleasant climate. But after the felling of tens of billions of cubic metres of timber and the construction of huge numbers of hydropower dams, the area’s hills have been left barren and unable to absorb rainfall.

        Let’s look at the forests first. The county of Zhouqu has historically been rich in vegetation, with 1,300 species of higher plant alone. In the past, 1,940 square kilometres of land was available for forestry, 65% of the county’s total area. Of this, 820 square kilometres, or 45%, was actually forested, a higher percentage than the Gansu and national averages of 7.5% and 22% respectively. Unfortunately, these forests have been decimated by three decades of felling. In the 1970s, 80,000 cubic metres of lumber were already being chopped down annually. Unchecked tree felling and trading eventually led to the county’s forestry resources diminishing by 100,000 cubic metres per year.

        Following last August’s devastating mudslide, reporters noted that the hillsides above the Sanyan valley, one of the worst hit areas, were bare of trees and even the brush was sparse. According to local elders, when they were in their teens the valley was covered with large trees. Once the hillsides were stripped, the villagers grazed goats here, worsening the environmental damage. Without the vegetation, heavy rain was able easily to loosen soil and stones triggering landslides that threatened lives and property below. 

        In addition to deforestation, widespread construction of hydropower dams has contributed to the area’s vulnerability. The Bailong River, the largest tributary of the Jialing, is 600 kilometres long, 450 kilometres of which flows within the borders of Gansu province. The rapid flow as the river passes down through the mountains makes this an ideal area for building hydropower facilities – and many have been built. But with no thought given to upstream ecologies, such projects have increased the likelihood of mudslides. The Bailong flows through a zone that is prone to earthquakes and the quarrying of stone from the banks of the river to build the dams has further destabilised the hillsides.

        Hydropower stations, both large and small, can be seen on any tributary of the Bailong. Surveys show there are as many as one thousand of them: big ones ranging in capacity from 200 to 300 megawatts, medium-sized ones from five to six megawatts and, more commonly, small dams of several hundred kilowatts each.

        These dams have all been built since the 1970s, almost in step with the rampant deforestation around them. Hydropower construction often conflicts with environmental protection goals. Dam-building has led to the destruction of forest reserves, for example, and intervention by the forestry authorities is rarely effective. Even though local government approval processes include an environmental impact assessment, since most hydropower projects are built with inward investment, ecology invariably loses out to hydropower.

        Between 2003 and 2007, contracts for 53 hydropower projects were signed in Zhouqu. Forty-one of these have since been built or are now under construction and the remaining 12 will soon follow. Together, they account for 80% of the county’s development projects. It is estimated that the 41 dams being built or already finished will result in the dredging of 38.3 million cubic metres of sediment and the loss of 749,000 tonnes of soil. On completion of a dam, water soaks the hillsides and loosens the earth, creating a situation where landslides could happen at any time. The dredging of sand also leaves the river bed covered in rocks which can be swept away by floodwaters, making those floodwaters much more dangerous.

        The third major problem we come to is building on river courses. Although mudslides and landslides have raised awareness of the dangers among local people, there is still a lack of urban planning and construction is still happening in vulnerable areas. The narrow valley floor on which Zhouqu lies is just 12 square kilometres in area. The population has been growing for decades, and the only place left to build is the river banks. Property developers see the Sanyan and Luojia rivers as their only option and have been buying up land for construction. Some people have built houses there. The densely-populated areas that were hit by the disaster – such as Yueyuan, Dongjie and Dongguan – are all alongside the rivers and have experienced explosions in property development.

        Zhouqu exploited its mountains, its water and its rivers and, in return, suffered a powerful mudslide. This is the national ecological disaster in microcosm. China endured 26,000 geological disasters from January to July last year, nearly four times as many as the same period in 2009. Around 200,000 geological risk points have been identified. Tens of thousands of these lie in mountainous provinces such as Yunnan, Guizhou, Sichuan, Chongqing, Gansu, Shaanxi, Hunan and Hubei and have the potential to unleash disaster on the scale of Zhouqu.

        The riches of economic development are not as valuable as green mountains and clear rivers. And it is ordinary, local people who are left to endure the impacts of environmental disasters. The suffering in Zhouqu is environmental suffering. It is time for an approach to human development that avoids putting environment, lives and property at risk simply for the sake of economic growth.


        (Jiang Gaoming is chief researcher at the Chinese Academy of Sciences’ Institute of Botany)

 

本文引用地址: http://www.sciencenet.cn/m/user_content.aspx?id=402466
* 本文仅代表博主个人观点,与科学网无关。
本文标签: 透支生态,自然灾害,泥石流,舟曲
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