The Sirikit Dam among others in the Chao Phraya basin were constructed beginning in the 1950s to exploit the agricultural and hydroelectric potential of the basin. Preliminary construction on the dam began in 1968 and it was finished in 1972. The power plant and first three units were commissioned in 1974, the fourth in 1995.[2] Previously in 1964, the Bhumibol Dam was completed on the Ping River, one of two major tributaries of the Chao Phraya including the Nan. The Bhumibol and Sirkit Dams control 22% of the Chao Phraya's annual runoff combined.[3] Both dams also help provide for the irrigation of 1,200,000 ha (4,633 sq mi) in the wet season and 480,000 ha (1,853 sq mi) in the dry season.[4]
Design
The dam is a 113.6 m (373 ft) high and 800 m (2,625 ft) long embankment dam that is 630 m (2,067 ft) wide at its base and 12 m (39 ft) wide at its crest. The dam withholds a reservoir of 9,510,000,000 m3 (7,709,882 acre⋅ft) of which 6,666,000,000 m3 (5,404,214 acre⋅ft) is active or "useful" storage. The reservoir has a surface area of 259 km2 (100 sq mi).[2] The dam's spillway consists of a tunnel controlled by two radial gates, it has a capacity of 3,250 m3/s (114,773 cu ft/s). The dam's power station contains 4 x 125 MWFrancis turbines for an installed capacity of 500 MW.[1][2]
Panorama of the Sirikit Dam, with on the right, the reservoir of the Nan River
