The year 2024 marks a momentous occasion for the development of water and hydropower resources in Pakistan, as the iconic Tarbela Dam turns 50 this year. After WAPDA completed the civil works of Tarbela Dam in the third quarter of 1974, water filling in the reservoir commenced 50 years ago.
Over the last five decades, Tarbela Dam has been a symbol of national pride. It is the capstone of the Indus Basin Plan, which ensures the continued and improved supply of water to millions of acres of irrigated land in Pakistan, mitigates floods, and generates green, clean, and affordable hydroelectricity to move the wheel of the national economy.
Tarbela Dam Project has been playing an instrumental role in economic development and social uplift in Pakistan during the last 50 years. The contribution the Tarbela Dam Project has made towards progress in the country can be judged from the fact that it has released 406 million acre-feet (MAF) of stored water from the reservoir for agriculture and contributed 590,361 million units of low-cost and environment-friendly hydel electricity to the National Grid. It is important to note that the economic and financial benefits of one MAF of water in Pakistan are estimated at
US$ 1,000 million (US$ 1 billion). Therefore, total benefits accrued from Tarbela Dam during the last 50 years stand at US$ 406 billion.
Tarbela Dam, the largest earth and rock-fill dam in the world at its completion, is located 64 km northwest of Islamabad. Construction on Tarbela Dam commenced in 1968, and all the civil works were completed in 1974. The development of powerhouses commenced in phases, starting in 1974.
The Tarbela Dam Project consists of a 9,000-foot (2,743 meters) long and 470-foot (143 meters) high barrier across the entire width of the river. It has two spillways with a cumulative discharge capacity of 1,500,000 cusecs (42,476 cumecs). Two auxiliary embankment dams close the low-level ridges in the left bank valley. A group of four tunnels, each 0.8 km long through the right abutment, were constructed for irrigation releases and power generation.
Tarbela Reservoir, which covers an area of 259 square kilometres, initially had a live storage of 9.68 MAF. However, due to sedimentation, it has reduced to 5.77 MAF over the last 50 years.
A power station on the right bank near the toe of main dam houses 17 power units at Tunnels 1, 2,3 and 4. Tarbela is the biggest electricity generation facility in Pakistan with installed capacity of 4888 MW – 51.6 % of the total hydel capacity of WAPDA. The installed capacity at Tarbela will further increase to 6418 MW after the under-construction Tarbela 5th Extension Hydropower Project is completed.
The cost of the Tarbela Dam Project, including power units 1 to 14, amounts to US $2,630 million. The cost of the Tarbela 4th Extension Hydropower Project, with power units 15 to 17, stands at US$1,075 million, while that of the under-construction Tarbela 5th Extension, with power units 18 to 20, is estimated at US $807 million.
