Impacts of magnitude and texture of variable sediment supply on bedload transport

Abstract

Sediment supply governs the bedload transport and bed morphology in rivers. Up to the present, the impacts of magnitude and texture of variable sediment supply (e.g., induced by flash flood from tributaries) on bedload transport are unknown, limiting the capacity of flood control and river management significantly. The present study conducted flume experiments to investigate the responses of bedload transport to variable sediment supply regimes with different peak supply rates and grain size distributions. The experimental results indicate that: the bedload rate and mass increase with increasing the peak rate of the variable sediment supply, and decrease with an increase in the proportion of coarse particles; the particles coarser than the median grain size of the supplied sediment D₅₀ are primarily stored in the bed, while those finer than D₅₀ are mainly transported downstream; during the variable sediment supply process, the critical Shields stress of sediment has a similar development trend to that of the bedload rate but with a slight ahead of time.