Hydroelectricity is an important source of energy in Pakistan. Most of the hydel plants in Pakistan are located on the rivers in the Mountainous North where the rugged topography provides a good head for the generation of electricity. A good head means that the water falls from a sufficient height on the turbine, making it turn. A regular flow of water is also essential to ensure the year round generation of electricity. Unfortunately, the rivers of Pakistan have a low discharge in the winter season which reduces their power generating capacity. As a result, power shortages generally occur in the winter.
A few low artificial water falls along canals have been utilized to develop small hydel plants. According to an estimate made by WAPDA, the hydel power potential of Pakistan is 30000 MW of which 20000 MW can be utilized economically. The installed capacity of hydel power plants was 4285 MW in 1999 -2000. At the time of independence, there were two hydel plants in Pakistan Renala and Malakand. Since then, several more important hydel plants have been built, including the largest projects, Tarbela, Mangla and Warsak.
Tarbela is a magnificent earth filled dam about 135 meters high on the Indus River. It is a multi purpose project which was primarily constructed to supply water for irrigation but also produces electricity. Its installed capacity is 3478 MW.
Mangla is another gigantic multi purpose project. It is located on the Jhelum River at the point where the River leaves the Mountains. Besides providing water for irrigation, it generates 1000 MW of electricity.
There are number of small hydel power plants in Pakistan. Their combined installed capacity is 107 MW. one of them is Renala, Located on the upper Bari Doab Canal. The demand for electrical energy in Pakistan is increasing rapidly. A quick solution of that problem is required.