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Ukai Project

The Ukai is the largest multipurpose project so far completed in Gujarat state. The Ukai dam is located across Tapi River near Ukai village of Fort-Songadh taluka in Surat district. Its catchment is located between longitudes 73°32'25" to 78°36'30"E and latitudes 20°5'0" to 22°52'30" N. The dam is located at about 29 km upstream of the Kakrapar weir. The total catchment area of the Ukai reservoir is 62,225 sq. km, which lies in the Deccan plateau. The catchment of the dam covers large areas of 12 districts of Maharashtra, Madhya Pradesh, and Gujarat. The districts that lie in the catchment include Betul, Hoshangabad, Khandwa and Khargaon of Madhya Pradesh; Akola, Amravati, Buldhana, Dhule, Jalgaon and Nasik of Maharashtra and Bharuch and Surat of Gujarat state.

The dam comprises a 4,927 m long earth-cum-masonry dam. The reservoir has a live storage capacity of 0.71 Million ha-m at FRL 105.156 m. The earth dam is 80.77 meter high above the lowest foundation level, while the masonry dam is 68.68 meter high above the lowest foundation. The storage extends irrigation facilities to an area of 1,522 sq. km under the Ukai left bank canal and Ukai right bank canal system besides firming up irrigation in an area of 2,275 sq. km under the command of pick up weir at Kakrapar. Thus, the total irrigation facilities provided are for 3,797 sq. km under Ukai and Kakrapar.

The Ukai head works were completed in the year 1972 after a construction period of seven years. There are 22 radial gates of 15.545´14.783 m size each. The length of the spillway is 425.195 m. The area under submergence due to the construction of reservoir (at FRL) is 601.30 sq. km, out of which 303 sq. km is in agricultural land, 223 sq. km is forest land and the remaining 75.30 sq. km is wasteland. In Ukai dam, 5.5 km³ of water is stored against the gates. This amounts to nearly 78% of the live storage. Thus, a large quantity of water is not stored against a static wall (the dam) but against a ‘live’ and moving device (gates). In such circumstances, operation of gates is very critical not only for the structural safety but also for flood control. This arrangement of storing large quantity of water behind gates has saved large chunks of land from permanent submergence thereby reducing the cost of the dam. Srisailam dam (Chapter 14) is another large dam where enormous volume of water is held behind gates.

The 75% dependable yield of Tapi River at Ukai dam site is 11,350 MCM. Out of this, the share of Gujarat is 3,947 MCM or 38.4%. This water is utilized to:

• Provide irrigation in 152,000 ha in the command of Ukai Left Bank and Right Bank canals,

• Firm up irrigation in 227,500 ha in the command of Kakrapar canals, and

• Generate hydropower up to 300 MW for 8 – 10 hours a day to meet the peak demands.

Initially, the Ukai dam toe hydro-power station with an installed capacity of 300 MW was planned as a peaking station and it was to be operated only for 8 to 10 hours in a day. In the initial years, with no upstream utilization in Maharashtra, the project was expected to generate about 990 MU annually. This was expected to reduce to 745 MU after 30 years and further to 587 MU after 60 years of operation, due to upstream development leading to reduced inflows to the reservoir. The actual performance of power house indicates that the stipulated generation of 900 MU was exceeded in 12 out of 25 years, the maximum annual generation reaching 1,233 MU in the year 1977-78. The reservoir also provides partial flood control in the downstream areas; Surat is the major city being protected.

Water utilized for power generation at Ukai Dam