Scour Profiles and Variation of Shear Stresses in Scour Holes Downstream of Adverse Stilling Basins

This research is focused on local scour downstream of adverse stilling basins where the flow jet was issuing from a submerged sluice gate. Totally, 233 tests were performed and 3262 scour profiles were recorded in a wide range of Froude numbers, sediment grain sizes, tail-water depths, stilling basin lengths and bed slopes. The results showed that the scour holes are self-similar at any slopes. A polynomial equation was derived to define the non-dimensional scour profiles at different slopes. In a certain condition of sediment grain Froude number, tail-water depth and length of basin, a change in the slope of basin from 0 to 15.6%, caused a decrease of 15% in maximum depth of scour hole. A theoretical approach was also derived to evaluate the bed shear stress, weight shear stress and shear stress at threshold state along the scour hole. It was found that the weight and bed shear stresses along the scour hole follow a time-dependent similar trend of variation. Finally, the geometry of basin was investigated to examine its effects on the weight and bed shear stresses.