March 02, 2007	Friday	Safar 12, 1428

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RAWALPINDI, March 1: The government is considering a proposal to construct a carryover reservoir upstream Khanpur dam with a storage capacity of 100,000 acre feet of water, sources told Dawn on Wednesday.

The proposal has been sent to the ministry of water and power for evaluation and carrying out a feasibility study. The sources said the much publicised Chirah and Dhadhocha dams would lose their priority if the site was found suitable.

The site is located some 25 kilometres upstream of Khanpur dam which could double the storage capacity of the dam. The original capacity of the dam was 107,000 acre feet in 1985, when it began supplying water for irrigation and municipal purposes. Today, silt has reduced its storage capacity to 93,000 acre feet of water. However, the quantity of silt is much lesser as compared to the assessment.

The requirement of municipal water in the twin cities is increasing day by day with growing population, and the delay in construction of Chirah and Dhadhocha dams is feared to aggravate the situation. Authorities are yet to decide about the availability of land for these two proposed dams.

An expert related to the Khanpur dam project described the proposed dam as highly economical and sustainable. A complete water supporting infrastructure right up to Sangjani water filtration plant and beyond duly linked up with all the three stakeholders — Rawalpindi Cantonment Board, Chaklala Cantonment Board, Capital Development Authority and the Rawalpindi Development Authority — is already existing on the ground.

It has been estimated that about 250,000 acre feet of water being wasted in almost every third monsoon season by opening of spillways of the Khanpur dam will be stored.

The expert said there was an excessive seepage of 70 to 80 cusecs of water through the bed of Khanpur dam as the bed was formed of limestone which got dissolved into water. If quality of water with its full capacity of proposed dam is stored upstream of the Khanpur dam, the seepage factor downstream will be considerably reduced. At the same time, the life of Khanpur dam will be enhanced may be twice as much owing to far lesser silting in it against the design calculations. It is likely to remain effective for next 150 years, he said.

The construction of a carryover dam will also help in mitigation of floods during excessive rains as both the dams will have storage capacity of over 250,000 acres feet of water.

Meanwhile, the storage level of the dam has increased to approximately 167 feet against the total capacity of 1,984 feet due to the recent rains. This level will be sufficient for the residents of Rawalpindi and Islamabad up to November, the expert said.