LAHORE: The weaning monsoon spell has already given a cumulative jump of 40 feet to the reservoirs and 1.8 million acre feet (MAF) additional water to the country over the past seven days, and its impact on the river inflows may last a few more days.

According to Wapda’s data, Tarbela Dam stood at 1,490 feet last Saturday (July 24), when the current monsoon spell — third in July — started, and had a 2.82MAF storage. By July 31, its level had increased to 1,518 feet and storage to 4.1MAF.

Similarly, Mangla Lake had attained 1,177 feet last Saturday and contained 3MAF water, which, in the next few days, went up to 1,189 feet and 3.6MAF, respectively. The river flows increased by 229,000 cusecs during the same week. Last Saturday, the cumulative water inf­l­ows stood at 348,700 cusecs, which were recorded at 577,700 cusecs a week later (July 31). River Indus alone produced as much water as all rivers combined (Indus included) produced last Saturday. It was flowing at 348,000 cusecs, Kabul chimed in with 70,700 cusecs, Jhelum 53,400 cusecs and Chenab 105,600 cusecs.

Irsa releasing 150pc more water than demand

On the basis of substantially healthy river inflows, the Indus River System Authority (Irsa) was providing water to the provinces according to their demand. Punjab is being granted 148,000 cusecs, Sindh 190,000, Balochistan 14,000 and Khyber Pakhtunkhwa 3,100 cusecs.

“In fact, Irsa is releasing more water than required because it does not have space to store additional water,” explains Khalid Idrees Rana, a spokesman for the authority.

Though the authority only has a 129,000 cusecs demand on the Indus arm, but it was releasing 290,700 cusecs. That is because Tarbela can only be filled by three feet a day up to 1,530 feet. Beyond that the filling criteria restricts it to two feet a day and the last 10 feet by only one foot daily. So, it is releasing almost 150 per cent more water than the requirement due to storage constraints. If Irsa had the option of rapid filling, it could have done so because it feared a drop in the Indus inflows.

The temperature in its catchment has started dropping: on Saturday, Skardu came down from 36 degree Celsius to 31 degrees, and the minimum temperature also dropped by six degrees. The authority is reading this warning seriously, he points out.

The farmers, though happy, are pinning their hopes on a drop in demand may help fill dams and a delayed start of monsoon delays its exit as well.

Agha Imran Khurshid of Vehari explains: “Except for the extreme southern part of the province, the entire Punjab has already received good showers, and the rain-producing system still persists. It should drop water demand and further help fill the reservoirs. Water would be required in September when crops (Kharif) maturity costs the country anything between four to 4.5MAF.”

Published in Dawn, August 1st, 2021