AT a water conference ‘Political Economy and Issues of Water Management’ held in Karachi some time ago, some speakers spoke of the desilting of dams for meeting Pakistan’s water needs.

Desilting Tarbela dam, where silt has continued to accumulate since early 1990s is impossible without disrupting hydropower generation and the downstream irrigation system for several years. The latest desilting or sediment flushing study of Tarbela dam, presented to the Senate in 2016, concluded sediment flushing is technically difficult and uneconomical with a negative rate of return. Allowing an unmitigated accumulation of silt in Tarbela reservoir was a mistake. This has depleted about four million acres feet of irrigation storage so far and continues that depletion at an average annual rate of 120,000 acres feet.

All out efforts should be made to save the remaining capacity of Tarbela reservoir by controlled sluicing out of fine silt with the help of appropriate technology, monitoring and controls, without disrupting the power generation and downstream irrigation system. Otherwise, Tarbela would also become a run-of-river project like Warsak dam.

Akram Khan

Lahore

Published in Dawn, June 29th, 2019