Energy dissipation at block ramps

Block ramps are hydraulic structures which are often used in practical applications both to control sediment transport and, at the same time, to assure a correct balance between hydraulic functioning and environmental impact. This structure typology have become more and more popular especially in the last century. The necessity to give eco-sustainable answers to hydraulic problems related to stream restoration has been considered essential, in the perspective of a correct balance between hydraulic structure performances and preservation of natural habitats. Block ramps could be considered one of the answers for the mentioned scenario as they minimize their impact on the contests in which they are located and offer several advantages in terms of both energy dissipation and sediment transport control. The construction techniques have been substantially improved during the last decades. In fact, this structure typology has been employed for wider and wider ranges of conditions and configurations. One of the main peculiarity is the capacity to dissipate a larger energy amount than other traditional transversal stream-restoration structures, such as check dams. Thus, significant efforts were spent by scientific community in order to optimize their energy efficiency. The present chapter aims to synthetize the actual knowledge regarding dissipative processes occurring in correspondence with block ramps. In particular, a critical discussion of the main parameters influencing the dissipative process is proposed and the main achievements present in literature up to the date are reported, in order to furnish a comprehensive summary which can be useful for both researchers and hydraulic engineers.