Tobias BOEHM, Christophe ANCEY, Philippe FREY, Jean-Luc REBOUD

An experimental investigation of bed load transport mechanisms for shallow water flow down steep slopes

Abstract: We present an experimental investigation into the 2D motion of coarse spherical particles entrained by a shallow turbulent water flow down a steep channel with a mobile bed. The solid discharge is adjusted at the upstream entrance so that, on average, there is bed load equilibrium. Filming the flows from a side and using an image processing software makes it possible to determine most of the flow characteristics: particle trajectories, change of state (rolling/saltating motion, rest), flow depth, and so on. A striking result of our preliminary experiments is that, over short time periods, bed load transport appears as a very intermittent process, resulting from the sudden occurrence of events such as entrainment or deposition of a series of particles.