Scour morphology at rock-bed sills for different spatial arrangements and geometric configurations

Bed sills are often used for river restoration. This structure typology contributes to stabilize bed slope and, generally, increases the energy dissipation. The erosive process occurring downstream of them is one of the most important issue to be solved and predicted in order to assure the correct hydraulic functioning of bed sills. Therefore, in the last decades, hydraulic engineers adopted innovative solutions, which could conjugate both the hydraulic aspects and the necessity to minimize structures impact on water bodies. In this perspective, rock-bed sills became very popular and widely adopted in river restoration projects. Nevertheless, there is still a lack of knowledge regarding their geometry optimization in terms of both scour depth reduction and equilibrium morphology. Therefore, experimental tests were conducted to simulate different rock-sills arrangements and typologies. This paper furnishes a preliminary analysis of the scour process downstream of rock-bed sills in a wide range of hydraulic and geometric configurations.