The Rehabilitation Solutions for the Hydraulic Jump Sweepout: A Case Study from India

Authors: Ali Heidari, Hany Saleem

Abstract:

The tailwater requirements are essential criteria in the design of the stilling basins as energy dissipation of the spillways. The adequate tailwater level that ensures the hydraulic jump inside the basin should be fulfilled by the river's natural water level and the apron depth downstream of the chute. The requirements of the hydraulic jump should mainly be checked for the design flood; however, the drowned jump condition should not be critical in discharges less than the design flood. The tailwater requirement is not met in Almatti dam, which became operational in 2002 in India, and the jump sweeps out from the basin, resulting in significant scour in the apron and end sill. This paper discusses different hydraulic solutions as a sustainable remedy for dam rehabilitation. As the most cost-effective, sustainable solution, the deep apron alternative is proposed for the fewer spillway bays. The apron level of 15 out of 26 gates should decrease by 5.4 m compared to the existing design to ensure a safe hydraulic jump up to the discharge of 10,000 m3/s, i.e., 30% of the updated Probable Maximum Flood (PMF).

Keywords: Dam, spillway, stilling basin, Almatti.

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