'Construction of large dams necessary as Indus inflows may increase'

LAHORE: Pakistan needs to concentrate on the construction of large dams as the inflows of Indus River is likely to increase during the first half of the 21st century due to de-glaciations caused by global warming. The inflows of the Indus River contributes 90 million acre-feet (MAF) out of 145 MAF to the country.

Water sector experts have pointed out that the World Bank has estimated that the increase may be within 20 percent to 50 percent during the first half of the century depending on annual temperature rise. However, during the second half of the century, there may be a corresponding reduction in the river inflows. The Indus River is the primary source of flows as well as possesses sites of large storages.

According to Riaz Nazir Tarar, a water sector expert, there is no other option except to conserve the surplus water through the construction of large dams to cope with a bleak scenario where the per capital water availability could come down to the acute stress level in 2025. Though recent approval of Diamer Basha Dam is silver lining to the cloud, at least one more project of similar size needs to be taken up for completion by 2030, he said, and added that in post-Diamer Basha period, a withdrawal level of 117 MAF (144.4 BCM) could be attainable against the target of 125 MAF (154.3 BCM).

Tarar said there has been an unfortunate complete moratorium on the construction of large dams after the commissioning of Tarbela Dam in 1976. The present situation warrants that the construction of large dams in Pakistan should be taken up on war footing.

It is conservatively estimated that hydropower potential of River Indus alone is about 40,000 MW. Therefore, the basic plank of generation expansion should be maximum harnessing of hydel potential. Besides an environment-friendly source of energy, this would save billions of US dollars to be spent annually on the import of fuel for thermal generation.

Pakistan possesses one of the world's largest contiguous irrigation systems. Presently, the Indus Basin Irrigation System (IBIS) serves 45 canals with a commend area of 35 MA (14Mha) through an extensive primary, secondary and tertiary system and three on-line storages with designed live capacity of 15.7 MAF or 19.4 BCM.

Suleman Najeeb, another expert, said in order to meet the projected irrigation demands by 2025, there will be serious shortfall of about 8 MAF or 9.9 BCM even with Raised Mangla and Diamer Basha reservoirs. This will require addition of at least another major storage by 2025 and preferably early for flood control to avoid repetition of damages like 2010.

All provinces will benefit from new storages. It has been assessed that whereas Punjab and Sindh would proportionately benefit to the extent of about 10%, the corresponding figures for NWFP (Khyber Pakhtunkhwa) and Balochistan would be about 25 percent and 50 percent, respectively.

Copyright Business Recorder, 2020