1960s Mangla Power House Under Construction

1960s Mangla Power House Under Construction



The Mangla Dam (Urdu: منگلا بند‎) is a multipurpose dam located on the Jhelum River in the Mirpur District of Azad Kashmir in Pakistan. It is the seventh largest dam in the world. The dam got its name from the village of Mangla. Major Nasrullah Khan of the Pakistan Army revealed for the first time in 2003, that the project was designed and supervised by Binnie & Partners of London (the team led by partner Geoffrey Binnie),[2] and it was built by Mangla Dam Contractors, a consortium of 8 U.S. construction firms, sponsored by Guy F. Atkinson Company of South San Francisco.[3]
As part of the Indus Waters Treaty signed in 1960, India gained rights to the waters of the Ravi, Sutlej and Beas rivers, while Pakistan, in addition to waters of the above three rivers within Pakistan and some monetary compensation, received the rights to develop the Jhelum, Chenab and Indus river basins. Until 1967, the entire irrigation system of Pakistan was fully dependent on unregulated flows of the Indus and its major tributaries. The agricultural yield was very low for a number of reasons, the most important being a lack of water during critical growing periods. This problem stemmed from the seasonal variations in the river flow due to monsoons and the absence of storage reservoirs to conserve the vast amounts of surplus water during those periods of high river discharge.[4][5]
The Mangla Dam was the first of the two dams constructed to reduce this shortcoming and strengthen the irrigation system of the country as part of the Indus Basin Project, the other being Tarbela Dam on River Indus.
Construction
Cost
Mangla Dam was constructed at a cost of Rs. 15.587 billion (US$1.473 billion) with the funding being provided by the World Bank and the Asian Development Bank.[6]
Reservoir
The dam was constructed between 1961 and 1965 across the Jhelum River, about 67 miles (108 km) south-east of the Pakistani capital, Islamabad in Mirpur District of Azad Kashmir. The Mangla Dam components include a reservoir, main embankment, intake embankment, main spillway, emergency spillway, intake structures, 5 tunnels and a power station. Besides the main dam, a dyke called Sukian – 17,000 feet in length and a small dam called Jari Dam to block the Jari Nala – about 11 miles beyond the new Mirpur town had to be constructed.
here was a total of 120 x 106 cubic yards (cu yds) of excavation for the reservoir whereas the total fill amounted to 142 x 106 cu yds and concrete to 1.96 x 106 cu yds respectively. The main embankment is earthfill with clay as the core material. Gravel and A-type sandstone are applied on the shoulders. The maximum height of embankment above the core trench is 454 feet and the length is 8,400 feet. The intake embankment is earthfill type with B-type sandstone as the core material. Gravel is applied on the shoulders. The maximum height of intake embankment above the core trench is 262 feet and the length is 1,900 feet.
Sukian Dam is earthfill with B-type sandstone as the core material. A-type sandstone is applied on the shoulders. The maximum height of the intake embankment above the core trench is 144 feet and the length is 16,900 feet.
JariDam is also an earthfill type with silt as the core material. Gravel is applied on the shoulders of the dam. The maximum height of Jari dam above the core trench is 274 feet and the length is 6,800 feet. The main spillway is a submerged orifice type with 9 radial gates, 36 x 40 feet each; it has a maximum capacity of 1.1 million cusecs. The emergency spillway is weir type with an erodible bund and a maximum capacity of 0.23 million cusecs. The 5 tunnels are steel and concrete lined and 1,560 feet long in bedrock. The internal diameter ranges between 26 and 31 feet.[7]
Power house
The power house, which consists of turbines, generators and transformers, has been constructed at the toe of an intake embankment at the ground surface elevation of 865 feet SPD. The water to the power house is supplied through five steel-lined tunnels of 30/26 feet diameter. Each tunnel is designed to feed two generating units. The power house tailrace discharges into New Bong Canal, which has a length of 25,000 feet with discharge capacity of about 49,000 cusecs, and terminates at an automatic gate control headworks at about 12 km downstream located near old Bong Escape Headworks.[8][9]
A view of turbine relief valve operation at Mangla Power House
There are ten vertical Francis type turbines in the power house. Each of these turbines has an output of 138,00 bhp with a rated head of 295 feet of water. The first four turbines were manufactured by Mitsubishi Electric, Japan and were installed in 1969, turbines 5 and 6 are manufactured by ČKD Blansko, Czech Republic and were installed in 1974, turbines 7-8 were manufactured by ACEC, Belgium and were installed in 1981, while the remaining two turbines are a make of Škoda, Czech Republic and were commissioned in 1994.[1][8]
These turbines are connected to umbrella-type generators which have a generation capacity of 100 MW. Hitachi, Japan had provided generators for turbines 1–4 and 7-8 while Škoda generators are connected to turbines 5-6 and 9-10.
These generators are in turn connected to three-phase transformers. The transformers connected to turbine 1, 4 and 7 were manufactured by the Italy-based Savigliano. The transformers for turbine 5 and 6 are a make of Italtrafo, another Italian company, while the remaining five transformers were provided by Škoda.#fastirtlinks.com