Hydraulic jump downstream of rock chutes

This paper shows the results of experimental tests conducted at the Hydraulic Laboratory of Pisa University on hydraulic jumps that occurs downstream of rock chutes. Rock chutes are structures used in steep channels to stabilize the bed. They are made of a rock mixture placed in two or more layers. A dissipation basin is located in the downstream section of the ramp in order to control scour processes. According to the base material of the stilling basin, the hydraulic jump which occurs downstream of the ramp toe assumes different configurations. Tests were performed to evaluate the main parameters that influence the behaviour of the dissipation process. In the investigated range, hydraulic jumps on mobile bed can be included in two categories: the first one is similar to a free jump, while the second one can be assimilated to a submerged one. The occurrence of one type in respect of the other depends on the values of the densimetric Froude number and of the slope of the ramp.