Alpine gravel-bed rivers are complex systems associated with specific morphologies (bars, riffles/pools, poorly sorted sediments, possible armouring). They are often subjected to anthropogenic activities and connected to ecological and economic issues. Their bedload dynamics have received much attention these past decades. Many bedload formulae have been proposed but they often fail to reproduce the dynamic of such rivers, especially when assessing low transport rates (Gomez and Church, 1989). In this paper, we focused on the low transport rate regime which is mainly driven by bed roughness using laboratory experiments. Our objective is to better estimate bedload rate qs at low bed shear stress using detailed information about bed morphology, which is the key factor to better understand gravel transport processes.