HARIPUR, Jan 19: The power generation capacity of the Tarbela Dam can be enhanced to 1,974MW from the existing 687MW if the Indus River System Authority accedes to Wapda’s demand for enhanced water release, an official source told Dawn.

“We can increase power generation to 1974MW right this day from the existing capacity of 687MW if Irsa allows us to release more water,” the source said, adding that despite repeated requests, Irsa had not allowed the Tarbela Dam authorities to release increased quantity of water, which could overcome the prevailing power crisis.

He said that on Jan 18 last year, the Tarbela Dam generated 925MW of electricity against the capacity of 2,336 megawatts, but the capacity had now reduced to 687 megawatts because the outflow of water had decreased to 10,000 cusecs, which was around 19,000 cusecs last year.

Answering a question, the official brushed aside an impression that the increase in water release would cause any harm to the dam, adding that although Tarbela’s storage capacity had decreased owing to accumulation of silt, there was hardly any factor that could cause any damage to the dam.

He said the unchecked sedimentation apparently because of massive deforestation in its catchment areas had developed a huge delta in the reservoir and that mass of sediment had reduced the storage capacity of the reservoir.

He said the delta as such had not damaged the dam but it had reduced its storage capacity. The delta is 50 miles long, 1 to 2 miles wide and around 200 feet deep. So this makes about 2.8MAF of silt deposited within the reservoir.

The designed storage capacity Tarbela was 9.68 million acre feet, but it had reduced to 6.9 MAF, the source said.

Answering a question, the source said Wapda had consulted teams of the USA and Chinese experts and different studies also showed that dredging was not an economical option.

The Tarbela dam, which has the total rated power generation capacity of 3,478MW, has a contribution of 60 per cent to the total hydel power generating system of the country.

The official said that on Friday morning, water level at the reservoir was 1,422.05 feet against its maximum conservation level of 1,550 feet. Water inflow was recorded at 22,000 cusecs and outflow remained 10,000 cusecs.