Erosive and hydrodynamic processes downstream of low-head control structures

Abstract

Low-environment impact structures have the advantage to conjugate both hydraulic functioning and environmental care. In particular, these structure typologies are widely used for river restoration both to control sediment transport and to dissipate flow energy. In the present paper, rock grade control structures, stepped gabion weirs, block ramps, and cross-vane weirs are analyzed and compared. Both similitudes and differences in terms of scour characteristics and dissipative efficiency are highlighted. The comparison shows that block ramps are the most efficient structures among those tested. Useful practical relationships are proposed in order to estimate both scour characteristics downstream of each structures and energy dissipation.