Local scouring at bed sills in a mountain river: Plima River, Italian Alps

The main characteristics of local scouring below 26 bed sills constituting a sequence of grade-control structures in a mountain river (Plima River, Italian Alps) have been surveyed. Bed sills were built with concrete strengthened boulders and other loose boulders were placed in the river bed to enhance habitat diversity for fish. The most likely formative water discharge is used to evaluate specific flow energy at each bed sill. Measured maximum scour depths are well predicted by an empirical equation developed through laboratory results, showing an average relative error of 0.15.