ISLAMABAD – The water storage capacity of Tarbela Dam has been reduced by40.58 per cent since its commissioning due to silting in the reservoir asa per Hydrographic Survey 2017.
As per results of Hydrographic Survey 2017 of Tarbela reservoir, sinceoperation the live and gross storage capacities of Tarbela reservoir hadreduced by 37.524 per cent and 40.58 per cent respectively.
Sources told APP here Friday that Inflow of sediment was a naturalphenomenon and could not be prevented. However, they said the governmenthad already taken steps for construction of Diamer Basha Dam which wouldhelp reduce the inflow of silt into Tarbela Dam.
The Diamer Basha dam would further enhance life of the Tarbela dam to 35years.
They said best possible arrangement would provide for an upstream storageto catch the sediment before entering the Tarbela reservoir.
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Water and Power Development Authority had conducted sedimentation studiesin the years 1987, 1991, 1997, 1998, 1999, 2007, 2013 and 2014 forevaluation of possibilities of de-silting Tarbela reservoir.
Quoting studies, they said, sediment flushing was uneconomical, technicallyrisky, impacts on the existing infrastructure would be overwhelmingresulting into increased variation in bed profile of downstream riversystem. It would also impact on barrage operations with increased sedimententering the canals, they said.
Additionally, it would accompany the loss of electricity generation atTarbela and Ghazi Barotha besides the loss of water storage for theirrigation purpose.
