Scour at the downstream of Ghatakeswar spillway using non-cohesive hydraulic model

Hydraulic model study was conducted on the 1:60 scale using 2-D model for mitigating local scour downstream of ski-jump bucket type energy dissipater under supercritical flow conditions with initial Froude number, F r1 from 5.50 to 6.29 for all gates vented condition. The objective of this research was to assess and quantify the scour in downstream side of channel and select the most appropriate existing formulas for predicting maximum scour depth of a local scour hole. The relative scour depth for the experimental data is compared with different empirical equations. Among these equations, a good estimate of the measured scour depth is obtained for the Novak and Indian standard equation. The developed statistical equations to predict scour depth give a good agreement with the experimental data. Each scour depth formula has limitations, therefore does not perform well with different discharges for different gate operative conditions. For depth of scour computation, the Novak method is found to provide high accurate results with Nash-Sutcliffe efficiency (NSE) of 0.91, root-mean-square error (RMSE) of 4.66 m and mean absolute percentage error (MAPE) of 15%. However, in a data-constraint situation, the development of a new formula for scour depths computation will be more feasible. © 2021 Indian Society for Hydraulics.