Experts redirect water to curb post-quake tragedies
Updated: 2013-05-23 05:36
By Erik Nilsson and Huang Zhiling (China Daily)
The 2008 Wenchuan earthquake rattled and crumbled the peaks that smatter Sichuan province's Longmen fault line, creating a recipe for later disasters. Just add water, and you get landslides.
So, the Wenjia Valley's landslip-prevention formula is to subtract the water from the loose soil and stones.
Experts constructed two dams and one diversion channel past the water source that fed six avalanches from the 2008 tremor until 2011. No landslides were recorded there before the quake.
The temblor jostled loose nearly 80 million cubic meters of Wenjia's mountains. Sichuan Provincial Geo-engineering Corp chief engineer Yang Quanzhong says about 30 million cubic meters are stable, while 50 million teetering cubic meters fan out over about a kilometer.
"This concentrated volume makes it a globally unprecedented problem," Yang says.
The wobbly earth splashes from 1,300 meters above sea level to the valley's trough.
Wenjia's mouth is Qingping township's only flat expanse. It's where a 2010 landslide raked 6 million cubic meters over the downtown that's home to more than 4,000 people - more than 90 percent of its population.
There haven't been any landslides since in Qingping.
"The diversion channel redirects water from the loose rocks and earth to prevent mud, while the dams block upriver tides of sludge and stones," says Sichuan Provincial Geology and Mineral Resource Exploration and Development Bureau deputy chief engineer Li Qianyin. Li worked with Yang to develop solutions.
Another consequence of the duo's labor is that metal-rod grids cage in many of the crushed slopes.
The 200 million yuan ($32 million) project began after roads, bridges, hospitals and urban and rural houses were rebuilt in Qingping.
Before the water diversion, people dreaded landslides every downpour.
Sichuan's governor Wei Hong explains: "Post-quake reconstruction achievements must be protected."
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(China Daily 05/23/2013 page10)