Mangla Dam Raising
Since its first impounding in 1967, sedimentation has occurred to the extent of 1.13 MAF, and the present gross storage capacity has declined to 4.75 MAF from the actual design of 5.88 MAF. The live capacity has declined to 4.58 MAF from 5.34 MAF. This implies a reduction of 19.22% in the capacity of the dam.
Unless measures were taken in time, this mega project would have become a dead dam in years to come. Since the design feature of the dam includes its raising to an additional 30 feet, the government of Pakistan decided in 2004 to go ahead with its raising project. Raising of the Mangla Dam will help into regain the reservoir capacity lost to sediment deposition and make provision for future sedimentation. Main features of the project include four earth dams with a maximum height of 454 ft. (154 meters) and total length of about 13 kilometres. For flood routing, two spillways are provided. The raising project will also generate construction activity and employment opportunities at large scale. The dam has already contributed significantly towards improvement of the environment in terms of agriculture growth, job opportunities and improved standard of living. Availability of additional water and hydro power will further enhance these positive impacts.
WAPDA inked a Rs.13.793 billion contract on June 28,2004 with CWE JV led by a Chinese Company China International Water and Electric Corporation for the construction of main works of Mangla Dam Raising Project in the stipulated period of 39 months ending September 19,2007. The local contractors in CWE JV include Descon Engineering, Interconstruct Gammon Pakistan and Sachal Engineering Works. The major components of the Mangla Dam raising works comprise raising of the dams and main spillway head works besides constructing a control weir upstream of the emergency spillway. Construction of an 18 kilometres long Mirpur bypass Road is also included in the contract. On completion of the project in 2007 the average annual water availability for irrigation releases would increase by 2.88 million acre feet (3,550 MCM). The power generating facilities of the original dam were designed for raised Mangla conditions. Hence additional energy will also be produced without making any alteration or addition in the power generating units. The average annual energy output is estimated to increase by about 12 percent of the present energy production. It is believed that the raising project will generate employment opportunities and give a fillip to socio-economic activities.
Salient Aspect of Raising Project
Reservoir: 1202 ft. (366.5m) from to 1242 ft. (378.7 m)
Minimum Operation Level: 1040 ft. (317.1 m) from to 1040 ft. (317.1 m)
Gross Storage Capacity: 4.5 MAF (5,553 MCM) from to 7.4 MAF (9,132 MCM)
Elevation of Control Structure: 1234 ft. (376.2 m) from to 1266 ft. (386 m)