Tarbela Dam

Tarbela Dam (د توربېلې بند, ) is an earth-filled dam along the Indus River in Pakistan's Khyber Pakhtunkhwa province. Located mainly in the Swabi district of the province, The dam is about from the city of Swabi, northwest of Islamabad, and east of Peshawar. It is the largest earth-filled dam in the world. The dam is high above the riverbed and its reservoir, Tarbela Lake, has a surface area of approximately . The Tarbela Dam is built on the Indus at Bara near the village of Tarbela. It is about 30 km from the town of Attock. When the Indus leaves the Himalayans foothills and enters the Potwar pleateau, the water is stored in the reservoir of the dam. It is 143 meters high, has an area of 243 square km, storage capacity of 119 billion cubic meters of water and has nine gates to control the outflow of water. The dam was completed in 1976 and was designed to utilize water from the Indus River for irrigation, flood control, and the generation of hydroelectric power by storing flows during the monsoon period and subsequently releasing stored water during the low flow period in winter. The installed capacity of the 4,888 MW Tarbela hydroelectric power stations will increase to 6,418 MW after completion of the planned fifth extension financed by Asian Infrastructure Investment Bank and the World Bank. The dam is at a narrow spot in the Indus River valley, named after the town of Tarbela in the Haripur District of Hazara Division, Pakistan. The main dam wall, built of earth and rock fill, stretches from the island to river right, standing high. A pair of concrete auxiliary dams spans the river from the island to river left. The dam's two spillways are on the auxiliary dams rather than the main dam. The main spillway has a discharge capacity of and the auxiliary spillway, . Annually, over 70% of water discharged at Tarbela passes over the spillways and is not used for hydropower generation. Five large tunnels were constructed as part of the outlet works. Hydroelectricity is generated from turbines in tunnel 1 through 3, while tunnels 4 and 5 were designed for irrigation use.