Block ramp for torrent control and stream restoration

One of the main problems for river engineers is the design of hydraulic structures which can control rivers natural dynamics and at the same time assure their environmental sustainability. In fact, especially in the last few decades, ecological and biological hydraulic structure's impact has become more and more important. Thus the main problem is to design an eco-friendly structure which is able to conjugate the traditional hydraulic scopes with a minimization of the environmental impact. Block ramps can be one possible solution. Block ramps are hydraulic structures which are generally used in mountain river restoration projects. They consist of either loose or fixed rocks disposed on a sloping bed. They can be inserted in stream corridors and can also be used as fish passages, as they don't break river morphology. Block ramps are structures which dissipate a big amount of energy, both on the ramp bed and in the downstream stilling basin. The dissipation is due to the localized stream slope variations and the high roughness conditions. Generally, a hydraulic jump takes place downstream of the ramp toe, thus a scour depth is formed which has to be controlled in order to assure the structure stability. The scour control can both be done by using a particular stilling basin granulometry downstream of the ramp toe or inserting structures like sills in opportune spatial positions in the stilling basin, which consent to minimize the scour lengths.