Dams and Landslides

Mud buries a county devoid of trees and plans

(August 17, 2010) Lumberjacks stripped slopes and builders ignored warnings before deadly mudslides devastated Zhouqu County.

(Caixin Online, Zhouqu) – Sixty years ago, the old-growth pine trees that covered all Sanyan Valley stretched to the sky from Cuifeng Mountain to most other peaks in the Zhouqu County region.

Vegetation flourished on the mountains on either side of the valley and along the Bailong River, a vibrant stream fed by abundant groundwater and hillside springs, according to the county’s almanac director Zou Weidong.

Today, however, much of the landscape is barren. Green is a rare color in the mountains. And from the town of Zhouqu, entire slopes visible to the north in the valley’s Bei Mountains are practically devoid of plant life.

Many scholars and local officials think deforestation and other manmade conditions played a significant role in the horrific mudslides that devastated this section of southern Gansu Province in early August.

More than 1,000 people died in the disaster, which started when torrential rains triggered floods and mudflows, burying more than two-thirds of the county’s land, including an entire village.

One forestry bureau source who asked not to be named said he primarily blames heavy, poorly planned logging during the 1950s and 1960s for Zhouqu’s tragic transformation from lush forest to virtual wasteland.

Large swathes of forest on the banks of the Bailong were wiped out by lumberjacks, who shipped logs down river to distant markets.

The government banned logging in several mountain areas in 1998 and hoped the pines would return. Nursery stock was planted up and down the mountains as well.

Nevertheless, today the dull brown of eroded soil is still the most common color along river banks in Zhouqu. Vegetation including recently planted trees struggle to survive on hillsides that lost much of what had been nutrient-rich soil during the lumbering era.

And the region has become much drier in recent years. Average annual precipitation locally has fallen from 650 millimeters to around 300 millimeters, and in recent years some springs have dried up. Experts say declining rainfall is a clear sign that logging seriously damaged Zhouqu’s environment.

Urban Sprawl

But deforestation was not the only form of human interference that harmed the local ecology. In addition, a swelling population and poor urban planning encouraged housing construction in environmentally sensitive areas along the Bailong that worsened the barren conditions.

According to a local government estimate, the town of Zhouqu’s population has risen sharply to 40,000 from around 20,000 in just the past 10 years. That’s been a serious challenge for a community with a total land area of less than 3 square kilometers.

As the area developed, local residents sold rights to build on collectively owned land to private buyers, mainly farmers who moved from other regions to Zhouqu. Land was bought and sold largely through a gray market without proper oversight from government planning and land-use departments.

Profit potential pushed sellers to take risks with eroded land. For example, buildings were erected in natural drainage ditches on slopes in the Sanyan and Luojia valleys. Even government-built channels designed to guard against mudslides were rendered useless when covered by new housing.

A lack of planning contributed to chaotic urban conditions along the river. Even now, Zhouqu urban construction bureau Deputy Director Yang Sanbao told Caixin, the county lacks a detailed city plan.

Yet the area has a history of mudslides that experts say should have given plenty of warning against the urbanization practices of the past decade. For example, a 1997 report by environmental researchers Ma Dongtao and Qi Long said the Sanyan Valley had been hit by 11 major mudslides since 1823, with the worst until this year occurring on June 4, 1992.

Ma, Qi and other experts inspected the valley for their research and submitted a comprehensive construction plan aimed at preventing mudslides. The plan called for fixing and stabilizing slopes, creating mudslide silt blocking systems and building better drainage.

But a 2007 report by the county’s Department of Water and Soil Conservation called the plan an “unfinished project.” It said from 1997 to 1999, the government completed construction of nine dam sites along with the first stage of a mudslide management project for the valley. Due to funding problems, the drainage system was never completed.

And because these hill-support systems were incomplete, the dams collapsed quickly and increased the damage during by the recent disaster.

Weak Warnings

But why were so many local people killed by the August mudslides? Didn’t they receive a warning?

Actually, an early warning system has been operating in Zhouqu near a mudslide hot spot since the late 1990s. Its China’s “first landslide early warning system, and is now the most extensive mudslide monitoring system in terms of scale and scope,” said Zhang Xiaolin, a senior engineer and director for the Yangtze River water conservation project committee.

Yet Zhang thinks the early warning system is unable to provide comprehensive monitoring. Rather, it only warns of pending disasters in certain areas, without looking more broadly when dangerous conditions threaten a large area.

The heavy rain that pelted the area August 7 – the day before the worst of the mudslides – fell unevenly in the Zhouqu region. As a result, Zhang said, “the rainfall monitoring by the early warning stations was not sufficient to issue a mudslide warning.”

Zhang added that nationally “it’s difficult for an early warning system to predict mudslides caused by torrential rainfall due to rapidly changing atmospheric conditions. Even if early warning centers cooperate with local meteorological departments, their ability to monitor climatic conditions is still limited.”

A lack of adequate funding means currently there are not enough early warning stations, Zhang said, and in many areas stations lack adequate equipment.

This is not the case at the Three Gorges Dam reservoir, however, in another part of China. Zhang said the project “has more early warning stations than the rest of the nation put together” – some 3,113 prediction and disaster prevention monitoring sites.

Another issue that contributed to the danger in Sanyan Valley was a lack of mudslide survival education and training for local residents.

The government sounded an air defense warning relatively quickly after the mudslides broke out in August. But local residents did not know what the warning siren meant, delaying evacuations and apparently increasing the fatality count.

The mudslides began in the morning, sweeping away half the village of Sanyan and engulfing the entire village of Yueyuan. Li Aihui, the county’s construction bureau deputy director in charge of planning, lost his entire family when mud buried their homes in Yueyuan.

After the earth settled, much of the land claimed by humans for buildings and urban development in recent years had been reclaimed by nature.

Yet the conditions that contributed to the disaster in Zhouqu are not uncommon in this part of the province. All of Gannan and Longnan regions have similarly same poor ecological conditions, making them just as vulnerable to mudslides. As a result, many people in the area now wonder which community will be the next Zhouqu.

Gong Jing, Wang Heyan and Zhang Ruidan, Caixin Online, August 17, 2010

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