Landslides and mudslides in the Beichuan region added to the high death toll in May’s earthquake. Now, writes Li Taige, familiar warnings are being heard. Will historic errors be repeated?
The quake left the town virtually flattened. Official statistics put the dead and missing at 13,000 – out of a population of only 40,000. The town is no longer habitable, and a memorial is to be built on its ruins.
Beichuan, the only Qiang-nationality autonomous county in China -- and under the jurisdiction of Mianyang municipality -- suffered not just from the tremors themselves but also from the landslides and mudslides triggered by the quake. If these geological-disaster risks had been considered when the county seat was located here or as it expanded, the destruction may not have been so total.
Beichuan before the earthquake
Beichuan lies in the north-west of the Sichuan basin, and has a history stretching back 14 centuries. However, the county’s administrative centre was moved to Qushan just over 50 years ago, in 1952. Why this was done is unclear, but one theory is that Qushan’s better outside links meant quicker reinforcements could arrive when bandits were at large.
The move, as the future would prove, was a mistake. Qushan lies in a narrow valley between steep mountains, and landslides are common in the area. Even without earthquakes, it is a dangerous place to live.
In an article published in 1992, Zhang Defan of Mianyang’s water management authorities pointed out that Qushan’s steep mountainsides, location on a fault line and complex geological conditions caused repeated landslides and mudslides. When the county seat was relocated, Qushan was home to only 500 people. Of course, the problems continued after the relocation.
In the 1980s, experts pointed out the risks of the location -- on the Longmenshan fault and between mountains. The locals started to worry that one day those mountains would bury them.
According to Caijing magazine, in the late 1980s the county authorities once suggested moving the administrative centre again – to the town of Leigu, which lies on flatter ground and indeed saw fewer deaths and less damage in the May earthquake. But funding for the relocation was not forthcoming and the experts could not decide if the move was necessary or not. The plans did not go ahead.
In his report, based on results of a survey of the area, Zhang Defan said that “the surrounding mountains are stable, and there is no chance of a collapse destroying the town.”
So the idea of moving the county seat was gradually forgotten, and the town continued to grow. But land was scarce. Qushan is surrounded by mountains and water, and there was only about a square kilometre of land available for building. A new part of the town was founded across the Jian River at Maoba. But Maoba itself lies at the bottom of a mountainside and is, again, a dangerous location. Despite this, plans for rapid expansion of the town were approved. By the end of 2005, it covered 1.6 square kilometres and had provincial approval for plans to expand to 4.1 square kilometres by 2020.
But the risks were not entirely forgotten. Materials from Beichuan’s Land Bureau show concerns about potential landslides and a number of reports were made to the provincial government. In 2004, work was carried out on the mountainside at Wangjiayan in the old town. In 2005, Wangjiayan was listed as a provincial-level project, winning funding of 1.52 million yuan (more than US$220,000). And in July 2006, work on columns to stabilise the slope, retaining walls and drainage was completed.
But when hit by such a huge earthquake, the value of these works was limited. Beichuan was buried.
As one survivor, who lost more than ten relatives in the quake, said: “If the mountainside hadn’t collapsed, not so many would have died.” Wang Zifa, head of the China Earthquake Administration’s Institute of Engineering Mechanics (IEM), said in an interview with Science and Technology Daily that half of the losses in Beichuan were due to the landslides.
Two thirds of China’s land is mountains and hills. Add in rain that tends to fall heavily over a small area, and landslides become a more frequent problem than earthquakes.
The mistakes made in Beichuan should not be repeated – but the existing situation is worrying. The locations of many towns and villages have not been well chosen.
In recent years the Chinese government has spent several billions of yuan on preventing landslides in and around the Three Gorges Dam, the world’s largest. But in many areas, funding is inadequate, if not severely lacking.
And to add to these existing dangers, new risks still are being taken. In some mountain areas, the geological conditions are ignored and towns are built on already unstable hillsides – raising the risk of disaster.
On May 1, 2001, a landslide destroyed a residential building in Wulong county in Chongqing municipality, killing 79 people. Part of the hillside had been removed to build a road, and private developers had excavated further in order to make room for the building.
On July 19, 2007, a mudslide near a hydroelectric plant in Tengchong county in Yunnan province buried barracks housing construction workers, killing 29 people. The China Institute of Geo-Environment Monitoring (CIGEM) blamed “engineering work”.
The destruction of Beichuan has sounded another warning. As Xu Qiang, deputy head of Chengdu University of Technology’s geohazard prevention laboratory, said in an interview with Caijing, landslide risk management and control must be made an integral part of urban planning and construction in mountainous areas.
Li Taige is a Beijing-based journalist. He obtained a master’s degree in engineering from Sichuan University in 1997 and was a Knight Science Journalism Fellow at the Massachusetts Institute of Technology (MIT) in 2003-04.