Mathieu Cassel, Hervé Piégay, Oldrich Navratil , Frédéric Liebault, Alain Recking , Daniel Vázquez Tarrío, Maarten Bakker , Sébastien Zanker, Clément Misset 

The monitoring of coarse sediment transport is a domain teeming with technical innovations and methodological developments aimed at improving the characterization of bedload processes at different spatial and temporal scales. Radio frequency identification (RFID) technology has improved sediment tracking experiments, allowing the characterization of processes at the individual particle and flood-event scales. Meanwhile, geophone sensors have enabled the continuous monitoring of bedload intensity and variations in sediment fluxes at intra-flood event and sediment-pulse scales. The combination of these two techniques allows these scales and processes to be linked. In this study, we used a combination of active ultra-high frequency RFID and geophone stations to link the virtual velocity of tracers with channel geophone activity, hydraulic forcing, and tracked particle properties, analyzing the results with single and multiple regression models. Our results show that compared with discharge or stream power, the geophone activity best explained the variance (81%) of the virtual velocity observed. Furthermore, when all the control variables tested were combined in an empirical model, the model explained 95% of this variance, and allowed quantification of the portions of the variance explained by hydraulic forcing, geophonic activity, and tracked particles. This shows the high potential of such monitoring combinations for future in-field experiments to investigate bedload processes in river systems of different morphologies at different spatiotemporal scales.