Energy dissipation in the stilling basin downstream of block ramps in presence of rock made sills

The dissipative process is one of the main topics for river engineers. It is deeply affected by both river morphology and the geometric configuration of the structures which can eventually be present in the river branch. In presence of a block ramp, previous studies allowed to analyze the energy dissipation mechanism for prismatic channels. The analysis was conducted for both submerged and free hydraulic jumps located at the toe of the block ramp with different stilling basin materials and different scale roughness conditions for scour equilibrium configuration, but in the absence of any protection structure in the stilling basin. Conversely, the aim of the present study is to analyze the dissipative process which occurs in correspondence and downstream of a block ramp when a rock made sill is located in the stilling basin. Moreover, the analysis of the dissipative process was conducted varying the spatial positions of the sill and the results were compared with the cases where no protection sills are present. The tests were performed using different stilling basin materials and varying the ramp slope. Moreover, in all the tests, the hydraulic jump was entirely located in the stilling basin, never submerging the ramp toe