Energy dissipation and hydrodynamic forces of aerated flow over macro-roughness linings for overtopped embankment dams

A promising solution to control overtopping and limit the risk of damage at the toe of an embankment dam may consist in dissipating a significant part of the flow energy along the chute by macro-roughness linings. In fact, compared to a smooth chute, the drag form effects due to the macro-roughness elements increase considerably the flow resistance. In order to define an efficient macro-roughness system, not only the energy dissipation needs to be estimated but also the hydrostatic and hydrodynamic forces on the macro-roughness elements.With this aim, an experimental research is conducted at the Laboratory of Hydraulic Constructions (LCH-EPFL), in order to define the aerated flow characteristics for a stepped flume. The presented results allow to compare the energy dissipation efficiency of conventional steps, steps equipped with endsills and steps equipped with alternate rectangular blocks for a 30◦ sloping chute, as well as to estimate the forces on the latter lining.