Review of plunge pool rock scour downstream of Srisailam Dam

The writer has used his own formulae, itself a derived improvement on 31 formulae by others, to estimate scour depth at Srisailam dam. The formula proved to be a reasonable fit to the measured scour depths at Srisailam and the associated unit flows. The formula was calibrated using key flood events to derive an equivalent bed particle size of 0.65 m as characterising the scour process at Srisailam. On this basis the probable deepest scour elevation at Srisailam, for the design flood, was determined. There is a certain asymmetry to the development of the plunge pool with the right hand side generally deeper than the left. Over the central section of the pool there appears to be a dominant upstream slope to the plunge pool of about 14°. This slope, projected from a central section of pool deepened to the maximum predicted elevation, would not seem to undercut the main apron.