ISLAMABAD, Aug 28 (APP):Total sediments deposited in Tarbela reservoir from 1974 to 2017 is 4.731 Million Acre Feet (MAF), Minister for Water Resources Makhdoom Khusro Bakhtiar told Senate Tuesday.
In a written reply to the question of Senator Syed Muhammad Sabir Shah, the minister
said the contribution of silt form Siran River is 0.192 MAF which is only about 4.05 % of the total sediment deposited in Tarbela reservoir so far.
He said it is notable that only 20% of Tarbela Watershed is under the influence of monsoon.
Seran catchment forms hardly 2%. The investment made for reducing sediment yield in this small
catchment area does not make it a viable project like at Mangla where almost
all catchment area is favourable for watershed checks and interventions.
He said technical investigation of various aspects of the sediment problem at
Tarbela have been performed by TAMS Consultants of the project since 1967.
The objectives of this study were to determine possible means of reducing the amount of sediments that would reach the reservoir.
The field reconnaissance covered the Indus river upto Parkuta and the lower reaches of Shyok,
Shigar, Hunza and Gilgit rivers.
The principal conclusion of the study was that watershed management and
upstream debris check dams could accomplish little towards reducing the
quantity of the sediments inflow.
He said there is no proposal under consideration of WAPDA to construct check dams
on various locations of river Siran to control silting in Tarbela Dam and avail
full benefits of the present storage capacity and production of electricity of
the dam.