Tarbela, Mangla dams to hit dead levels this month

March 08, 2014 - 1:29:17 am
LAHORE: Tarbela and Mangla dams may hit the dead levels by the middle of this month as water planning by the Indus River System Authority goes awry, and the shortage crosses the 15 percent mark against the expectation of 7 percent for the last three months of the Rabi season.

By the end of January, Irsa planned to carry over 600,000 acre feet of water - 300,000 acre feet each in the two dams - for the Kharif season with reservoirs lasting till the end of the Rabi season.

With water flows dropping exceptionally, the plans are now under threat. Irsa may not be able to save 600,000 acre feet of water and the dams may not last till the end of this month to provide water for the Kharif season starting on April 1.

Both targets were based on calculations of inflows recorded in the last three months of Rabi.

Irsa had revised calculations of water shortage from earlier 15 percent to 7 percent in January and the provinces planned consumption at that rate.

On the basis of these estimates, Irsa had planned to keep Tarbela at 1,414 feet by March 6 and Mangla Lake at 1,103 feet. They are now down to 1,413 feet and 1,094 feet, respectively, as inflows continue to drop and the provinces insist on substantive withdrawals for the standing crops, especially wheat.

Yesterday, Punjab was still withdrawing 51,000 cubic per second (cusec), Sindh 30,700cusec and Khyber Pakhtunkhwa and Balochistan 10,000cusec each against the total national supply of 45,800cusec only.

River flows were enough to meet only 50 percent of national irrigation requirements with the rest coming from the reservoirs. Against the Irsa calculation of a shortage of 7 percent, Punjab had already taken a hit of 12 percent and Sindh 10 percent by the end of February, but water supplies have worsened further.

“We have been pressing for more water because it is required for the fast maturing crops,” says an official of the Punjab irrigation department.

Irsa is counselling restraint but there is high demand of water from provinces against dwindling supplies.

Both dams have over one million acre feet of water - Tarbela has 0.586maf and Mangla 0.552maf - and it will be imprudent to save 60 percent of it for the next season and let the existing crops suffer. 

The department fears that if March turns out to be hotter, additional water would be required urgently.

The province is preparing for that scenario, whereas Irsa wants it to reduce even the existing consumption.

The Pakistan official said his department wanted the same amount of water till March 20 for the wheat crop which is being supplied now.

Irsa is being forced to supply water even if dams get empty. If the provinces draw water according to the shortage of 7 percent, the dams would go down almost instantly.

Even if withdrawals are made at 15 percent shortage, the dams may not last third week of the current month, he concluded.