All big dams have sedminentation problem. The gravity of this particular problem is directly proportional to the quality and the quantity of incoming sediments.
At present, the Indus Basin is utilizing 106 million acre feel (MAF) of water to irrigate 36 million acres of land as a result of taming the over-flows and the resultant water storage facilities. However, by the year 2010, the storage capacity of available water reservoirs would be reduced from 18.37 to 6.3 maf due to the perpetual natural phenomenon of silting up. Sedimentation is a natural process and is the result of perpetual erosion, a process having little human control.
The process depletes the storage capacity, pronounces the chances of clogging of tunnels due to delta liquefaction and increases chances of abrasion effects on hydro mechanical installation tremendously due to heavy concentration of sand particles. Severe vibrations and cavitations are also experienced at power turbines due to these concentrations.
With the passage of time, the available quantity of water will keep on decreasing due to further silting up of the Tarbela, Mangla and Chashma lakes. And only timely measures could help overcome the perpetual decay process. Otherwise, Pakistan would land in dire straits of severe water crisis, difficult to be resolved.
In the natural process of silting, only Mangla lake will suffer a loss of 1.6 maf storage. The raising of Mangla Dam is a part of the efforts to overcome the problems because of water shortage and thus secure the future of the country. The geographical and environmental conditions, it may be appreciated, are quite congenial for the raising of the dam so as to replenish the lost capacity behind the massive structure.
The groundbreaking to raise the dam by 30 feet, by President General Pervez Musharraf on September 30, 2002, marked the initiation of development work at the fourth fast track project in the first phase of the gigantic Vision-2025 Programme aiming at contributing to attain the national goals of progress and prosperity. The vision is the second large development outlay after the Indus Basin Resettlement Project in Pakistan.
On completion of the project in next five years, 2.9 million acre feet more water storage will be made available in the Mangla Lake for Indus River System. Besides this, 180 mw or 772 million units of low-cost hydro-electric power annually will be available from the same power station housing 1,000 MW installed capacity. The three fast track Vision: 2025 projects taken up in August-September 2001 i.e. Gomal Zam Dam, Mirani Dam and Greater Thal Canal are progressing as per schedule. The Mangla Dam raising is one of the three more recently launched projects. The other two newly launched projects are the Rainee Canal and Kachhi Canal in the provinces of Sindh and Balochistan respectively.
The raised dam project will ultimately yield Rs 800 million per annum worth financial benefits to the country’s economy as a result of better irrigation management from 7.4 MAF of water stored here and 772 million units additional generation annually from the same 1,000 mw Mangla power station.
As the Mangla lake will extend consequent to the raising of the Mangla Dam by 30 feet, therefore for the population to be affected, a comprehensive, liberal and attractive ‘rehabilitation and resettlement package’ has been developed which offers a lucrative financial and welfare package to the affected people. It is being so planned that the social and environmental problems to come up during the process could be better resolved. In order to compensate the possible impacts and loss an unprecedented package includes vocational training along with opportunities for provision of jobs.
The non-agriculturist affected persons would be trained at the vocational training centres to be established in the model city and town. These measures will provide maximum job opportunities where they would be able to invest the money given to them as compensation of losses. Under the package, the old Mangla dam affected persons who could not have land at that time will also get Rs200,000 per family. Moreover, in compensation for loss of house, 10 percent more than the cost of a new house will be given. A minimum of Rs300,000 will be paid as compensation to the owners of the smallest house .
The affected persons who have built their houses on the government land will also be given a five-marla plot free of cost. The owners of land will enjoy the facility of ploughing their fields during the period when the level of water in the reservoirs goes down and the submerged land dries up. For rehabilitation of the affected persons, a new model city near Mirpur besides four model towns in Dudial, Islamgarh, Cak Sawarai and Siakh areas will be developed. Basic amenities in these towns and city will be provided from within the cost of the project.
On completion of the project and its becoming operational, the Azad Jammu and Kashmir government will be receiving Rs700 to 800 million annually as royalty of the dam; the people of Azad Jammu and Kashmir will get drinking water from the Mangla Dam and additional water requirements for their agriculture lands will also be taken care of. The AJK government will also command fishing rights of Mangla lake while the government will also be owning the rights of providing recreation facilities in the Mangla lake and developing tourism facilities there.
In award, the electricity tariff for the people of Azad Jammu and Kashmir will be Rs2.32 per unit that is half of the per unit price in Pakistan. In addition, to improve upon the supply of power in Azad Jammu and Kashmir, six new grid stations and 265 kilometres of 132 KV capacity power transmission lines will be constructed in the next five years. Besides these facilities, the Rs1.4 billion electricity dues outstanding against AJK government have also been written off. The Dhan Gali bridge will be constructed by Wapda at a cost Rs250 million while the Mirpur-Islamgarh bridge will be constructed by Pakistan.
All the big rivers of Pakistan originate from, or enter into Pakistan through, Kashmir. The water storage capacity of Tarbela, Mangla and Chashma reservoirs is continuously decreasing because of the quantum of silt flowing into the lakes with river waters. In 1967, when Mangla Dam was built, water storage capacity of the reservoir behind the dam was 5.8 MAF which has been reduced by 20 per cent due to silting up in the last 35 years. The primary objective of raising the Mangla Dam is to make up this lost water storage capacity.
The ground reality that Pakistan, with increasing population is fast heading towards a water-short country, can be gauged from the fact that, in the year 1951, the per capita water availability was 5,650 cubic meter which has by now dropped to 1,350 cubic meter per person. To save a country from falling among water-short countries, 1,000 cubic meter per person water availability is the must. From this angle, by the year 2012, Pakistan would have landed in the state of a severe water-short country as by that time the Tarbela, Mangla and Chashma reservoirs would have lost one-third of their capacity which means that by the year 2010, we would have lost physically, the quantum of water equivalent to a big reservoir.
The raising of Mangla Dam project has been programmed to be completed by June 30, 2007, at a cost of Rs59 billion which includes the cost of ‘rehabilitation and resettlement package’ for the affected persons.
(The writer is the Director,Public Relation, Wapda)