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REGISTRO ITALIANO DIGHE

Ufficio Periferico di Cagliari

versione italiana


 

Tarbela Dam

 

 

Country

Pakistan

River

Indus

Dam type

Zoned earth/rockfill.

On the left bank, two auxiliary dams have been built to close saddles at the upstream end of a side valley. The two dams have a structure similar to that of the main dam, and are constructed with the same type of materials.

On the same left bank are also located two spillways discharging into the side valley.

Construction period

1968-1976

Structural height

148 m

Gross storage capacity

Originally 14,300 Mm. Due to silt carried by inflowing water, to the extent of 130 Mm per year since 1974, sedimentation has taken place, which has reduced the gross reservoir capacity from 14,300 Mm to 10,500 Mm.

Active storage capacity

Originally 12,000 Mm

Volume of the dam

- Main dam: 121,000,000 m;

- Auxiliary dams: 14,000,000 and 1,500,000 m;

- Spillways: 800,000 m of concrete.

Maximum controllable water surface

472.44 m a.s.l.

Crest elevation

477.00 m a.s.l.

Crest length

- Main dam: 2.740 m;

- Auxiliary dams: 710 and 105 m.

Maximum discharge capacity

The service spillway, with seven radial gates, has a discharge capacity of 18,400 m/s, while the auxiliary spillway, which has nine radial gates and a similar structure, has a discharge capacity of 23,800 m/s.

Nameplate capacity of the powerplant

The powerhouse, located on the right bank just downstream of the main dam, was completed in 1977 with four 175 MW turbine-generator sets, providing an overall power of 700 MW. Four units, for further 700 MW, were added in 1982. Two more units, for 350 MW in all, were completed in 1985, and finally four other units, providing an overall power of 1,728 MW, were completed in 1992-93, making the total power generation capacity of Tarbela Dam 3,478 MW.

Notes

The Tarbela Dam is the largest earth and rockfill dam of the world. Its volume of 121 million m, largely exceeds that of other huge embankment dams, like Aswan in Egypt (43 million m), Nurek in Tajikistan (58 million m) and Akosombo in Ghana (8 million m).

The River Indus carries a large volume of suspended sediments. The progressive silting of Tarbela reservoir could impede, in some decades, an useful efficiency of the dam.

 

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Ultimo aggiornamento: 4 agosto 2005