LAHORE: Owing to the exemplary implementation of Mangla Watershed Management Project during the last 55 years, the life of Mangla reservoir has enhanced from 110 years to 212 years.
This was stated in a briefing made to the Authority in the meeting presided over by WAPDA Chairman Zafar Mahmood, held here at WAPDA House. WAPDA Member (Power) Badrul Munir Murtiza and the officers concerned attended the meeting.
It was briefed that the consultants of Mangla Dam in their design of the project way back in late 1950s, had envisaged life of the Mangla reservoir from 100 to 110 years with an estimated sediment load at the rate of 42,000 acre feet per annum. However, due to effective measures taken under the Watershed Management Project, the assessed rate of sediment load has reduced to 2774 acre feet annually, adding more than a hundred years to the life span of Mangla reservoir. The volume of benefits because of the Mangla’s enhanced life could be better assessed with the fact that the benefits equivalent to billion of rupees are accrued every year from Mangla Dam, it was added.
The meeting was told that Mangla Watershed Management Programme has been continuously implemented since 1960 in reservoir’s catchment area, covering 5710 square miles in Azad Jammu and Kashmir (AJK) and Pakistan to control soil erosion and reduce sediment rate. Some of the measures taken under the project from 1960 to 2015 include plantation of about 133 million trees, construction of dry stones and earthen structures measuring 122 million cubic feet in the form of check dams and retaining walls etc., construction of 4000 engineering structures of stone masonry dam and drop spillway etc., improving 8400 acres of cultivated land and imparting training to the farmers.
It is pertinent to mention that Mangla Dam was constructed in 1967, while its Raising Project was completed in 2011. Subsequent to its completion, the raised Mangla Dam is now the largest reservoir of the country with storage capacity of 7.48 million acre feet (MAF), surpassing Tarbela Dam which can store 6.4 MAF.
During the briefing, the Authority expressed satisfaction over the reduced rate of sedimentation flowing into Mangla reservoir. The Authority also decided to acknowledge the services of all those who had contributed over the last 55 years towards managing the sediments. They will be honoured in the Golden Jubilee Celebrations of Mangla Dam, planned in 2017. A letter will also be written to the consultants, who supervised construction of Mangla Dam in the late 1950s and 1960s regarding successful implementation of Watershed Management Programme and enhancement of reservoir’s life by another 100 years.
The Authority set the target for 2015-16 of planting 1.325 million saplings spread over an area of 1960 acres. It was also decided that third-party-evaluation-mechanism will be adopted by involving local non-governmental organizations (NGOs) for the purpose. In addition to the plantation of trees, soil conservation structures equivalent to 3.774 million cubic feet and 183 engineering structures will also be constructed during the current financial year under this programme.
It is worth mentioning that Warsak Dam constructed across River Kabul in 1960, was completely silt-up in just six years. One of the contributing factors to rapid silting was that it did not have any watershed management programme.