Fast-moving delta in Tarbela Dam a serious threat

August 14, 2022

ISLAMABAD: The fast-moving delta in the Tarbela reservoir that is present at a distance of four miles from the main structure is posing a serious threat and can choke down the irrigation and power generation system. The delta is moving at a speed of a quarter of a mile each year, top officials of the water resources ministry said.

The officials cautioned that a sudden earthquake could also increase the potential danger of clogging due to liquefaction of bottom set and fore set slopes would increase as the delta moves closer to the dam.

The Senate Standing Committee on Water Resources on Friday held an in-camera session on the details regarding the violation committed by India under the Indus Water Treaty, causing water scarcity in Pakistan, but the deliberation was deferred till the next meeting. Senator Syed Muhammad Sabir Shah chaired the meeting held to discuss details regarding the starred question raised by Senator Seemee Ezdi in the Senate sitting on the violations committed by India.

Earlier, while taking a briefing on the issue of silting at the Tarbela Dam, the committee was briefed by the joint secretary, ministry of water resources, that “the delta movement is a constant threat to choke down the Tarbela reservoir”.

Wapda General Manager Mr Azam, during a briefing on the issue of silting at the Tarbela Dam, informed the committee: “At present, the delta is four miles away from the reservoir and moves with a speed of 0.25 mile/annum. The delta movement is apprehended to hit the structure of the Tarbela reservoir. The committee was apprised that the percentage loss in gross and live storage capacity was 43 per cent and 39 per cent respectively. “The option of de-silting of the Tarbela reservoir has been considered and its pros and cons have been evaluated that de-silting of the Tarbela reservoir will choke the entire irrigation system,” the official informed the committee.

Senator Taj Haider expressed reservation on the analysis but suggested dredging starting from a smaller scale from where it was pivot and the storage of the silting as possible solutions. He also pointed out that since silting was apprehended in the Tarbela Dam, de-silting tunnels were constructed that were never being operated.

The ministry also informed the committee that the primary purpose of the Tarbela Dam and the Mangla Dam was to regulate the flows of the Indus River for irrigation use and not to generate electricity and the power units were also closed for generating electricity.

The secretary, ministry of water resources, said that through the construction of the Dasu Dam, the sediments on upstream could be contained that could save the Tarbela reservoir.

Senator Muhammad Hamayun Mohmand raised a question on the non-construction of the Bhasha Dam which was to be constructed in 2017.