This paper presents a theoretical and experimental study related to the impact of a submerged jet below a high vertical drop on a loose material bed. The theoretical analysis, based on hydrodynamic evidences, seeks the flow characteristics at the scour surface as a consequence of the jet flow field evolution. Sediment equilibrium conditions allow obtaining the overall scour shape as well as the maximum scour depth and downstream length. Laboratory experiments provide the quantitative parameters needed to calibrate a closed form computing algorithm. Further experiments on a different lab setup, as well as literature data are used for testing. The method provides results of general validity in a wide range of cases, with a greater accuracy than the one shown by predicting formulas derived from regression analysis, as usually used in grade control structure design.
