China began damming the Jinsha River on Wednesday to build the Xiluodu hydropower plant, the second largest of its type next to only the massive Three Gorges Project.
The damming started at 9:30 a.m. and is expected to last 36 hours at Xiluodu where the river is 47 meters wide, said Wang Shukai, vice director of the project under the China Three Gorges Project Corporation.
The river's runoff reached 3,520 cubic meters per second, up from an estimated 3,200 cubic meters, due to rainfall in the upper reaches of the waterway.
Earlier, workers burrowed five channels into mountains located upstream and have diverted more than half of water to bypass the dam.
With a designed installed capacity of 12.6 million kilowatts, the Xiluodu plant will be the nation's second largest hydropower plant after the Three Gorges Plant. When completed, it will be the third largest of its type in the world.
The dam will be 278 meters high with a reservoir containing 11.57 billion cubic meters of water.
The project started construction in 2005 and is expected to be operational in 2015.
Jinsha River, a major tributary of the Yangtze River, flows between Yushu in Qinghai Province and Yibin in Sichuan Province. It is seen as having excellent potential for hydropower resources.