Tarbela Dam

Tarbela Dam
Image of the Tarbela Dam from space
Official name	Tarbela Dam
Location	Tarbela, Pakistan
Construction began	1968
Opening date	1976
Construction cost	USD 1,497 Million [1]
Dam and spillways
Impounds	Indus River
Length	2,743.2 metres (9,000 ft)
Height	143.26 metres (470 ft) from river level
Reservoir
Creates	Tarbela reservoir
Total capacity	13.69 cubic kilometres (3.28 cu mi)
Catchment area	168,000 km2
Surface area	250 km2
Power station
Turbines	10 x 175 MW, 4 x 432 MW
Installed capacity	3478 MW

Tarbela Dam (Urdu: تربیلا بند‎) on the Indus River in Pakistan is the largest earth filled dam in the world and second largest by structural volume.^[2][3][4] It is located in Haripur District, Hazara Division, Khyber Pakhtunkhwa, about 50 kilometres (31 mi) northwest of Islamabad. The dam is 485 feet (148 m) high above the riverbed. The dam forms the Tarbela Reservoir, with a surface area of approximately 250-square-kilometre (97 sq mi). The dam was completed in 1974 and was designed to store water from the Indus River for irrigation, flood control, and the generation of hydroelectric power.^[5]

Description

Tarbela Dam

The project is located at a narrow spot in the Indus River valley, at Tarbela in Haripur, shortly located at the point from where the District Swabi then starts. Here the river formerly split around a large island close to the left bank. The main dam wall, built of earth and rock fill, stretches 2,743 metres (8,999 ft) from the island to river right, standing 148 metres (486 ft) high. A pair of concrete auxiliary dams spans the river from the island to river left. The spillways, located on the auxiliary dams, in turn consist of two parts. The main spillway has a discharge capacity of 18,406 cubic metres per second (650,000 cu ft/s) and the auxiliary spillway, 24,070 cubic metres per second (850,000 cu ft/s). The outlet works are a group of four tunnels that have been cut through the valley wall at river right, for uses of hydropower generation and flow control. These tunnels were originally used to divert the Indus River while the dam was being constructed. A hydroelectric power plant on the right side of the main dam houses 14 generators fed with water from outlet tunnels 1, 2, and 3. There are four 175 MW generators on tunnel 1, six 175 MW generators on tunnel 2, and four 432 MW generators on tunnel 3, for a total generating capacity of 3,478 MW. Tarbela Reservoir is 80.5 kilometres (50.0 mi) long, with a surface area of 250 square kilometres (97 sq mi). The reservoir holds 11,600,000 acre feet (14.3 km³) of water, with a live storage of 9,700,000 acre feet (12.0 km³). The catchment area upriver of the Tarbela Dam is spread over 168,000 square kilometres (65,000 sq mi) of land largely supplemented by snow and glacier melt from the southern slopes of the Himalayas. There are two main Indus River tributaries upstream of the Tarbela Dam. These are the Shyok River, joining near Skardu, and the Siran River near Tarbela.

The Tarbela Dam is the second largest in terms of dam volume in the world.

Settlement of Tarbela Dam affectees

It has a reservoir area of about 260 square kilometers and about 82,000 acres land was acquired for its construction. The large reservoir of the dam submerged 135 villages, which resulted in displacement of a population of about 96,000 people.^[6] For the land and built-up property acquired under the Land Acquisition Act of 1984, a cash compensation of Rs 469.65 million was paid to the affectees. In the absence of a national policy, resettlement concerns of the affectees of Tarbela Dam were addressed on ad hoc basis.

Many affectees of the Tarbela Dam have still not been settled and not been given land as compensataion by the Government of Pakistan, in accordance with its contractual obligations with the World Bank.^[7]

Lifespan

Because the source of the Indus River is glacial meltwater from the Himalayas, the river carries huge amounts of sediment. The annual suspended sediment load is about 430 million tons. This means that, over time, the reservoir will fill. The useful life of the dam and reservoir was estimated to be somewhere around fifty years, since the dam's completion in 1976, meaning that the reservoir would have been full of sediment by 2030.

However, sedimentation has been much lower than predicted, and it is now estimated that the useful lifespan of the dam will be 85 years, to about 2060.^[8]

Tarbela-IV Extension Project

In September 2013, Pakistan's Water and Power Development Authority signed a Rs. 26.053 billion contract with Chinese firm Sinohydro for executing civil works on the 1,410 MW Tarbela-IV Extension Project.^[9] Work on the project will be completed in three & half years at an estimated cost of $928 million.^[10] In June 2013, the World Bank had agreed to provide a $840 million loan for the project.^[11]

On completion, the project will increase the generation capacity of Tarbela Hydropower Station to 4,888 MW from the existing 3,478 MW after installation of three units of 1,410 MW on Tunnel No 4.^[9][12] and add about 3.84 billion units cheap electricity to Pakistan's national grid per year. Annual benefits of the project were estimated at about Rs. 30.7 billion.^[10]

See also

• List of dams and reservoirs in Pakistan
• List of barrages and headworks in Pakistan

External links

• A family trip to Tarbela Dam

Notes

Coordinates: 34°05′23″N 72°41′54″E / 34.0897222222°N 72.6983333333°E / 34.0897222222; 72.6983333333

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