Kaptai Dam

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Background:

At the time of partition of Indo-pak sub-continent, in the year 1947, power generation and distribution of this part of the country were in the hands of some private companies. Power supply to the 17 provincial districts was within the township in a limited way, the generation voltage was 400 volts. In Dhaka City power used to be supplied by two 1500 kW generators and the generation voltage was 6600 volts and this was the highest supply voltage. There. Besides, power used to be generated by some industries (tea, sugar and textiles) and railway workshops. Cotton Mills, Pahartali Railway workshop, Saidpur Railway workshop and Sugar Mills were amongst them. In aggregate the generation capacity of the country was 21 MW. The generation capacity of the power utility companies together was only 7 (seven) MW and there was no transmission system.

In 1948, Electricity Directorate was created to plan and improve power supply situation, and in 1959, Water and Power Development Authority (WAPDA) was created. At the same time Kaptai dam was taken up.

The Dam:

The earth-filled dam Kaptai is an earth-fill dam. It is 45.7m (36m MSL or mean sea level) high and 670.6m long. The maximum width is 7.6m and width at the foot is 45.7m. The 16-gated spillways, each 12.2m by 11.3m, can together pass a flow of 625,000 cusec. The average annual flow in the reservoir is approximately 15,646 MCM. The flood absorption capacity is 8.25 million Ac-ft and the flooded area at 33m MSL is 777 sq km.

In 1962, the the dam, spillway, penstock and 2 units of powerhouses were built. Each of the powerhouses was capable of generating 40MW of electricity. In November 1981 another 50MW generating unit was completed. In October 1988 the 4th and 5th generating units were installed raising the total generation capacity to 230MW. The total cost of work was Tk. 1,900 million. The spillways on the left side of the main dam have discharge capacity of 625000 cusec with the 16 gates (each 12.2 m X 11.3 m). The construction of these system (dam, spillways and others) required to excavate 113400 cubic m. The dead storage at 23.16m above MSL is 1.18 million ac-ft. Flood storage capacity is 0.83 million ac-ft.

The 11000 km2 catchment area of the reservoir of the Kaptai dam claims 220 km2 of cultivable land of which 40% cultivable land in this area and displace 18000 families submerging a total of 655 km2.