Islamabad: The Tarbela Dam, a cornerstone of Pakistan’s infrastructural development, marks its 50th anniversary this year. As the largest earth and rock-fill dam globally at its completion, it has significantly contributed to the country’s socio-economic growth by providing irrigation, flood mitigation, and hydroelectric power.

According to Pakistan Water and Power Development Authority, the Tarbela Dam was completed by WAPDA in the third quarter of 1974, and the reservoir began filling the same year. For five decades, the dam has played a crucial role in the Indus Basin Plan, aimed at enhancing the water supply for millions of acres of agricultural land, reducing flood risks, and generating sustainable hydroelectric power.

The dam’s impact over the years includes the delivery of 406 million acre feet of water for agriculture and over 590,361 million units of hydel electricity to the National Grid. The economic benefit of one million acre feet of water is estimated at approximately US$ 1 billion, bringing the total benefits to around US$ 406 billion.

Located 64 km northwest of Islamabad across the River Indus, the Tarbela Dam features a 9,000 feet long and 470 feet high embankment. It boasts two spillways with a combined capacity of 1,500,000 cusecs, and auxiliary embankment dams that secure the river’s left bank valley. The dam originally had a live storage capacity of 9.68 million acre feet, which has reduced to 5.77 million acre feet due to sedimentation over the past 50 years.

The dam’s power station houses 17 power units across four tunnels, making it Pakistan’s largest electricity generation facility with an installed capacity of 4,888 MW, which is 51.6% of WAPDA’s total hydel capacity. The capacity is expected to increase to 6,418 MW upon the completion of the Tarbela 5th Extension Hydropower Project.

The cost of the Tarbela Dam Project, including the initial 14 power units, was US$ 2,630 million. The cost of the 4th Extension, featuring units 15 to 17, stood at US$ 1,075 million, and the ongoing 5th Extension, with units 18 to 20, is estimated at US$ 807 million.