Dachaoshan Dam

The Dachaoshan Dam is a gravity dam on the Lancang (Mekong) River in Yunnan Province, China. The sole purpose of the dam is hydroelectric power production as it supplies water to a power station containing six 225 MW generators for a total installed capacity of 1,350 MW.

Background
Initial construction preparations on the dam began in 1993 before it was approved ready for construction in 1994. On August 4, 1997, the project was approved for construction commencement and on November 10, 1997, the river was diverted. Between 2001 and 2003, the dam was complete and all six generators went operational.

Design
The dam is a 111 m tall and 460 m long gravity dam. It is composed of 1126700 m3 of concrete, 756600 m3 is roller-compacted concrete. The reservoir created by the dam has a capacity of 940000000 m3. To release water downstream, the dam has five 14 m x 17 m crest openings along with three mid-level openings and one bottom flushing outlet. With these openings, the design flood discharge capacity of the dam is 18000 m3/s while the maximum is 23500 m3/s.

The dam's power station is underground and supplied with water via six 179.5 m long penstocks. Once through the six turbines, the water exits back to the river by means of two tailrace tunnels, one 1355 m long and the other 1248 m.