noncohesive sediment scour downstream of an apron

the effect of grain size, tailwater depth and grain froude number on local scour caused by submerged horizontal jets issuing below a sluice gate was investigated. noncohesive sediments with two gradations downstream of a horizontal apron were used in the experiments. the experiments were carried out at different inflow froude numbers and a range of tailwater depth from low to high submergence. variations in the maximum depth of scour, height of dune and longitudinal extension of scour hole were plotted by tailwater depth, grain size and grain densimetric froude number. results showed that the effect of tailwater depth depends on the grain densimetric froude number. also, the similarity between non-dimensional scour profiles, one of the most controversial problems in previous studies, was proven. finally, the extension of scour hole was plotted in the form of nondimensional parameters that can be used in any unit system.