Mechanized excavation to drain Yunnan quake lake

The arrival of specialist heavy machinery has allowed workers to begin racing at full speed to drain an earthquake-formed barrier lake which is threatening residents of Yunnan Province with flooding.
The machinery has made a huge difference to work to dig a deep canal through a wall of the lake and cause the water level to subside, said Chen Jian, director of the provincial water resources bureau, who is overseeing the excavation work at the site, on Saturday.
The barrier lake is located near the border of Ludian and Qiaojia, which were at the center of the earthquake and in which most of the deaths occurred. It was formed when 12 million cubic meters of landslide rubble blocked the Niulan River, and has already flooded more than 370 homes.
Chen said the speed of the lake's swelling has slowed down, after workers used dynamite to expand a drainage tunnel belonging to a hydropower station located 600 meters upstream from the barrier lake. The drainage tunnel is diverting part of the river's flow away from the lake.
On Saturday morning, the water level in the lake was increasing by a few centimeters per hour, as compared with 60-80 centimeters per hour in the past few days.
Chen said the river's flow in the past few days has also become more stable as there have been no heavy downpours in the region.
In the past seven days of search and rescue work, it had been difficult to transport large machinery to the site. Rescuers helped evacuate more than 8,100 local residents away from the river's reaches.
Chen said the blockages are mostly big rocks. Explosions have been set to blow them up, while heavy machinery is important for excavation.
A headquarters dedicated to the quake lake is eyeing opening the eight meter-deep canal through the blockage before Tuesday.