The world’s largest earth filled dam is Tarble Dam and it the second largest dam by the structural volume. Tarbela Dam is located on Indus River in Khyber Paktunkhwa’s Hazara Division’ District Haripur. From Islamabad, it is about 50 kilometers northwest. The height of dam is 485 feet above riverbed. It was completed in 1976, and it was designed in the way so it could store water for irrigation, generate hydroelectric power and to control flooding.
At Tarbela in Haripur this project is situated on the narrow spot in the Indus River Valley. District Swabi starts from the point of this dam’s location. Close to the left bank and around the large island this river formerly splits. The main wall of the dam stretches 2.743 meters to river right from island and is made of earth and rock fill, and it is 486 feet high. The river is extended from the island to river left by a pair of concrete auxiliary dams. On the auxiliary dams, spillways that consist of two parts as well are located. 18,406 cubic meters per second is the discharge capacity of the main spillway and 24,070 cubic meters per second is the discharge capacity of the auxiliary spillway. A group of four tunnels called outlook workers at right river, have been cut through the valley wall to flow control and hydropower generation.
At the time of dam construction, these tunnels were used to divert the Indus River water. On the right side of the main dam, a hydroelectric power plant houses fourteen generators fed with water from outlet tunnels 1,2 and 3. Total generating capacity of these three tunnels is 3,478 MW. On tunnel 1there are four 175 MW generators, on tunnel 2 there are six 175 MW generators and on tunnel 3 there are four 432 MW generators.
Reservoir of Tarbela is 80.5 kilometer long and the surface area is 250 square kilometers. 11,600,000 acre feet of water is contained by the Tarbela Reservoir with 9,700,000 acre feet of live storage. The Tarbela Dam’s catchment area of upper river holds the area of 168,000 square kilometer of land. Snow and melted glaciers from the southern slopes of the Himalaya increase the water amount in it. The Shyok River near Skardu and Siran River near Tarbela are two Indus Rivers tributaries upstream of the Tarbela Dam.
In terms of volume, this dam is the world’s second largest dam.