ISLAMABAD: For the first time in over half-a-decade history, the country’s three reservoirs — Mangla, Tarbela dams and Chashma Barrage — attained their maximum capacity on a single day putting total water storage at the highest 13.443 million acre-feet (MAF). This raises hopes for bumper crops both in the current Kharif and coming Rabi season.

“By the Grace of Almighty Allah, Tarbela, Mangla and Chashma, the three major water reservoirs of Pakistan, stood filled to maximum conservation levels (MCLs) on the same date on 17.08.2023 with a total impoundment of 13.443 MAF. The filling of all the three major storages on the same date is a historical event,” said Indus River System Authority (Irsa) on Thursday.

The three reservoirs have “filled to their maximum level, resulting in the maximum availability of water in the dams, which is being regarded a good omen for agriculture and hydel power generation in Pakistan in the days to come”, said reservoir operator Water and Power Development Authority (Wapda) to mark the rare event.

Irsa said the current storage capacities of the reservoirs include Mangla Dam’s 7.356 MAF at maximum conservation level of 1,242 feet followed by Tarbela’s 5.809MAF at 1,550 feet and Chashma’s 0.278 MAF at 649 feet. “Filling of the reservoirs was a very important parameter of system operations as it controlled and stored excess waters and flood flows during Kharif for inter-seasonal transfer to low flow Rabi in winter season to meet with the provincial demands.

The precarious operation of reservoir filling was reached amid numerous natural and technical challenges in the form of impending hydrological uncertainty due to climate change and the current system and reservoir constraints. “It was feared that very low early Kharif flows of 2023 could also suppress late Kharif flows, correspondingly”, said Irsa but noted that fortunately widespread rains in upper and lower catchments of all the rim-stations during late Kharif 2023, especially the eastern rivers, allowed relevant stakeholders to efficiently manage and regulate the provincial releases with the integrated operation and filling of the reservoirs.

It may be recalled that Kharif season had started with 37pc anticipated water shortage with 27pc shortages in early Kharif and about 10pc in late Kharif. There will be no shortage in the late Kharif.

Luckily, eastern rivers — Ravi, Beas and Sutlej — flowed with sufficient water after a gap of more than a decade and enough water is available in the system downstream of these rivers, reducing the need for discharges from Mangla dam. From now onwards, all inflows would have to be released into the rivers and canal system. The flows in eastern rivers are also a sign of climate change that weather and flow patterns have differed after a gap of 10-15 years, giving a warning to the people downstream to keep safe distances from old river beds.

On top of this, Indian reservoirs on Sutlej and Beas are now again nearing maximum levels at Bhakra and Pong storages.

There are two principal crop seasons in Pakistan, namely the Kharif, in which sowing begins in April and harvesting in October while and the Rabi, which begins in October and lasts till April. Rice, sugarcane, cotton, maize, mong, mash, bajra and jowar are Kharif crops while wheat, gram, lentil (masoor), tobacco, rapeseed, barley and mustard are Rabi crops.

Published in Dawn, August 18th, 2023