Bedload tranport rate fluctuations in a flume with alternate bars under steady state conditions.

Bedload transport rate in gravel-bed rivers under steady flow conditions shows large fluctuations (Singh et al., 2009). The development, destruction and migration of bedforms (Gomez et al., 1989; Recking et al., 2009), in combination with grain sorting (Iseya and Ikeda, 1987), were identified as the main processes creating fluctuations. Past observations were often qualitative, and thus further investigations are required to better understand the role played by these processes in the intermittent character of the bedload transport (Church and Ferguson, 2015). In this study, we experimentally investigate the effect of alternate bars on the fluctuations of the bedload transport rates under steady state conditions. The experiments are performed during long periods of time (hundreds of hours) in order to account for long time scale processes and characterize any possible equilibrium state.