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On shaky ground

The devastating mudslide in Zhouqu last month was far from a one-off, write Lu Zongshu and Tang Jing. Millions in China are threatened by geological disaster – and they need protection.

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On August 7, a huge mudslide struck Zhouqu, in Gansu, western China. By August 16, more than 1,200 people had been declared dead and 490 were still missing. According to Xinhua news agency, this was the worst landslide in Zhouqu since records began, and possibly the worst in China for 60 years.

Zhouqu is one of China’s landslide hotspots. In recent decades, it has experienced many such disasters. Official records show that one of the areas worst affected this summer – Sanyanyugou – was also hit by mudslides in 1978, 1989 and 1992. These events destroyed or damaged 842 buildings and killed or injured 196 people. 

Last month’s mudslide happened at 10pm, following two hours of torrential rain. According to the meteorological authorities, 90 millimetres of water had fallen – a historical record. But it seems nobody was alerted to the danger, perhaps because it was already dark.

In the days following the disaster, the Ministry of Land and Resources said the landslide had been caused by a complex range of factors, including the location in an area prone to geological disasters and the effects of the Wenchuan earthquake in May 2008, and that it would have been almost impossible to foresee the event.

However, as early as 2002, the area was included in a geological-risk survey carried out as part of a Gansu project to provide early warning of such disasters. A report of the findings was completed by the China Institute of Geo-Environment Monitoring (CIGEM) in March 2003.

CIGEM told Southern Weekend that the report looked at 140 danger zones, covering the location, size, stability, risk level and potential losses of each. Sanyan and Luojiayu villages, which were both hit by the August mudslide, were listed as very high risk, as over 1,000 people were deemed to be in danger. The report demanded that the authorities “do not let down their guard and promptly provide the funds for risk reduction in order to prevent mudslides occurring”.

In June 2008, following the Wenchuan earthquake, a group of experts from Beijing visited Zhouqu and identified 60 potential landslide sites, rating 13 of them as a serious threat to the villages below and in need of remedial measures. Two years later, the disaster struck.

The main issue, according to Zhou Pinggen, head of CIGEM’s geological risk survey and monitoring office, is that the region has been through almost half a century of unrestrained logging. Year by year, forests have declined and the environment has been damaged beyond its capacity to recover. By the time local government woke up to reality and started planting trees to stabilise the soil, the vegetation was unable to take root on the steep, thinly soiled slopes.

Past media reports have also described aerial photographs taken by the State Bureau of Surveying and Mapping, showing mountaintops stripped bare and spots of green only visible in the gullies. And a 2003 study on Zhouqu by Gansu’s geo-environmental monitoring centre found that road building in the mountains had, to a certain extent, raised the chances of geological disaster. 

Former minister for land and resources, Sun Wensheng, once said that rural areas, particularly poor mountainous regions, have always borne the brunt of China’s geological disasters. This is supported by statistics showing that rural areas suffer 80% of the deaths, injuries and property damage caused by such events.

In the first half of 2010, only five of the 21 “very large” or “large” geological disasters to strike China hit cities, according to the National Geological Disaster Bulletin. The rest affected rural areas.

The bulletin also states that there were 19,552 geological disasters in that period – 10 times as many as seen in the first half of 2009. Deaths and financial losses also rose sharply. One hundred and forty seven of these incidents were fatal; in total, 326 people died, 138 went missing and 1.86 billion yuan (US$273 million) worth of damage was done.

Zhou Pinggen, of CIGEM, explains that extreme weather events are one of the causes of frequent geological disasters. Another factor is the recent wave of construction projects to build new dams, expressways, railways and buildings on the sides of mountains. He says China has 16,000 danger zones like Zhouqu, and the lives and property of seven million people are under threat. These zones are mostly located in mountainous provinces such as Yunnan, Guizhou, Sichuan, Chongqing, Gansu, Shaanxi, Hunan and Hubei.

Any of these potential disasters could strike at any time. The head of the Geological Disasters Group at the Chinese Academy of Geological Sciences, Wu Shuren, says that current funding, technology and personnel are only sufficient for tracking basic geological risks in 1,640 counties. But danger points concealed underground and the disasters they might trigger in the future are not properly understood.

Since 2009, the Ministry of Land and Resources has implemented a nationwide mechanism for the public to monitor and deal with risks, with some success. Figures suggest this has averted 209 geological disasters. But Wu says the accuracy, depth and scale of the work is still far from adequate. Currently, only basic indicators such as cracks in walls are monitored. Danger points that are further away, less understood and better hidden cannot be checked with simple measuring tools.  

A recent incident in Sichuan province, western China, illustrates the problem. While a particular slope behind a dam construction site had been the subject of close monitoring, on June 14, a landslide one hundred metres up the opposite side of the gully sent rocks and mud flying over the river, crushing a workers dormitory and killing 23 people.

Even more worrying for those responsible for geological monitoring was last year’s landslide in Wulong, near Chongqing in western China. According to reports, it was the third in a series of landslides (the others were in 1994 and 2001) that have killed a total of 169 people. In 1994, the cliff face where the slides have all originated was identified as a risk, an early warning system was set up, locals were relocated and checks were put in place in a bid to eliminate any risks. But in 2009, tragedy struck again and 74 lives were lost.

Yin Yueping, vice chief engineer of the China Geological Survey, visited Wulong after each incident. He says that they had predicted another collapse, and expected 200,000 cubic metres of earth to flow 100 metres to the east. In fact, there was a landslide of 7 million cubic metres, flowing 1,500 metres north – 90 degrees wide of the forecast.

Zhou Pinggen says that the majority of China’s counties do not have geological monitoring stations. Where they do exist, remote locations mean visits are rare. Two years ago Ya’an in Sichuan managed to employ two university graduates in the field, but within a year both had left for further study. Meanwhile, the state system for public monitoring and prevention of geological disasters focuses more on rewards than punishments, and is easily ignored by local government. Unfortunately, the next Zhouqu might soon be on its way. (UPDATE: Since this article was published by Southern Weekend, at least 16 people have died and 32 were still missing after landslides struck the village of Wama in Yunnan province, south-west China.)

Lu Zongshu is a reporter for the Southern Weekend and Tang Jing an intern. The original article was published on August 12 in Southern Weekend and has been edited by chinadialogue

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Default avatar
匿名 | Anonymous

预测

我宁愿看到地质专家们诉苦,说缺少经费,缺少设备,缺少人手,也不能接受他们说“泥石流是不能预测”的。至少前者的问题是我们的投入不够,可以改善。后者根本就是在说瞎话。

Forecast

I'd rather have geologists complaining about the lack of funds, the lack of equipments, the lack of manpower, but I can't accept them saying "landslides cannot be foreseen." At least the former problem would be about our insufficient inputs, and it could be changed. The latter is simply talking nonsense.