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REGISTRO ITALIANO DIGHE

Ufficio Periferico di Cagliari

versione italiana


 

Akosombo Dam

 

 

Country

Ghana

River

Volta

Reservoir

Lake Volta

Dam type

Rockfill with clay core

Construction period

1961-1965

Structural height

134 m

Gross storage capacity

148,000 Mm

Active storage capacity

85,000 Mm

Volume of the dam

7,991,000 m

Maximum controllable water surface

84.1 m a.s.l.

Maximum water surface

84.7 m a.s.l.

Crest elevation

88.4 m a.s.l.

Crest length

671 m

Maximum discharge capacity

Spillway: 20,000 m/s;

Powerplant: 6 x 263 m/s.

Nameplate capacity of the powerplant

1,038 MW (6 units generating 173 MW each), producing 4.8 TWh per year

Notes

Lake Volta is the 5th largest man made in the world by storage capacity.

During the construction of Akosombo dam, many difficulties were successfully overcome. A deep dredging was effected removing 1.2 million m of sand overlying the main river bed rock foundation. A special feature of the project construction technique is that two coffer dams, one upstream and one downstream over 60 m high from the foundation, had to be constructed under water. These rockfill dams were constructed by tipping and sinking from both the banks of the river, along with the progressive dredging. Clay blanketing of the upstream face of the upstream coffer dam and the downstream face of the downstream coffer dam was effected to dewater the foundation area. These coffer dams later formed an integral part of the main dam. During construction, in 1963, a hundred years frequency flood occurred which was about 4,200 m/s more than provided by the diversion arrangements (10,000 m/s). This caused a great dislocation but progress was maintained and the project was completed well ahead of schedule.

 

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Ultimo aggiornamento: 4 agosto 2005