LAHORE: Following extensive snowing spells over medium and high reaches in the north, brimming rivers in summer are expected to keep water availability levels sufficient in the forthcoming Kharif season, thereby meeting irrigation and drinking needs in the Indus Basin, officials said on Tuesday.
The overall water availability in Kharif 2021 (April 1-September 30) would be in surplus. However, it has been estimated that during early Kharif period between April-May, a shortage of nearly 10 percent would occur as far as river flows were concerned, a senior official said. “This is primarily due to minimal carryover and late snowmelt in the lower catchments,” he added.
According to data compiled by Water and Power Development Authority (WAPDA), less-than-normal rains and prolonged winter in upper parts of the country have led to generally low flows in all rivers in later Rabi season, while Kabul River, which enters Pakistan from Afghanistan and Chenab River, originating from India, witnessed abysmally small volumes in particular. The consistent flow trend in contrasting breadth and depth of catchment area shows widespread declining river flows in almost the entire Indus Basis, the official said.
Unlike previous years, the inflows of both these transboundary rivers have been in single digit since November last year till now, barring a few days of over 10,000 cusecs each. The inflow of Kabul River, having a bigger tributary originating from Pakistan in north-west upper reaches, was astonishingly hovering around barely 2,000 cusecs for several days in March. A hydrology expert dubbed such nominal flows of Kabul River during March 8 to March 12, 2021 all-time lows.
Official told this scribe that system flow this year was markedly low if compared with last year and the trend shown in previous ten years. Quoting figures, he said, combined inflows of all four live Indus Basin rivers including Chenab, Jhelum, Indus and Kabul was 45,200 cusecs on March 10, 2021 against last year’s flows of 92,000 cusecs recorded on the same date and 70,000 cusecs average flows registered on corresponding day of last ten years.
The negligible carryover, low flows on the back of little rains and late melting of sown would lead to low flows to some extent in upcoming early Kharif season if compared with normal average flows. However, the official said, there would be hardly any tangible impact on farm-gate water withdrawals due to better rotation practice.
He recalled that efficient water regulation mechanism in later Rabi season helped cope with the challenge of brisk depletion of Tarbela Dam on the recommendation of Wapda with a view to facilitating hydropower extension work on tunnel.
What water regulators have done to solve unwarranted higher-than-demand outflows from the dam included employing an innovative approach to save almost entire outflows of Mangla Dam. These Mangla flows were later utilised in February and March this year when there was little water left in Tarbela Dam.
Talking about high flows from May onward in later Kharif season 2021, the official said that with acceleration in snow melting and thundering precipitation of monsoon, river flows would surge. “It is assessed that more than 12 million acre feet of water would go into seas through Indus Delta below Kotri Barrage after meeting all irrigation and other requirements,” the official added.