Ujjani Dam - Features

Features

The Ujjani Dam commissioned in June 1980 is an earth cum concrete masonry dam, which has created a multipurpose reservoir. The total length of the dam is 2,534 m (8,314 ft), which comprises a central portion which is the spillway dam of 602 m (1,975 ft) length, of concrete gravity section of 56.4 m (185 ft) (maximum height above the deepest foundation level). The spillway is flanked by Non Overflow (NOF) concrete gravity dams of 314 m (1,030 ft) length. Earth dam sections flank the NOF dams on the left and right banks. The volume content of the dams is 3,320 km3 (800 cu mi). The gross storage capacity created is 3,320.00 km3 (796.51 cu mi) at the Full Reservoir Level (FRL) of 497.58 m (1,632.5 ft). The spillway, structure has an Ogee shaped downstream slope designed to dispose a design flood discharge of 15,717 m3/s (555,000 cu ft/s) (the maximum probable flood discharge of 18,013 m3/s (636,100 cu ft/s) and a breaching section is provided between the NOF block and the earth dam section, controlled by 41 radial gates of 12 m (39 ft)x6.5 m (21 ft) size erected over the crest of the dam. In addition, four river sluices (gate controlled) are also provided in the body of the spillway pier numbers 3, 4, 5 and 6 with outlet level at 470 m (1,540 ft), with each sluice designed for a discharge capacity of 60 m3/s (2,100 cu ft/s) for silt flushing. The energy dissipation arrangements on the downstream slope of the spillway is in the form of high level and low level slotted roller bucket type. Measuring instruments have been installed in the body of the dam to record and analyse various parameters related to the behaviour of the dam over the years as part of the dam safety programme The dam is founded on massive basaltic rock formations.