Modeling Bedload Transport Trajectories along a Sine-generated Channel

Abstract

This study explores the influences of flow discharge and particle size on bedload transport trajectory by applying a depth-averaged two-dimensional model to a 110° sine-generated laboratory flume with wide-and-shallow sections. Calculated results exhibit two erosion regions in a bend: Zone-1 ‒ foreside of the point bar near the convex bank and Zone-2 ‒ near the apex of the concave bank. Sediments eroded from Zone-1 are mainly transported along the same-side convex bank rather than crossing the channel centerline, indicating the crucial role of longitudinal flow in shaping point bars. Most particles from Zone-2, however, behave more complicated by changing their trajectories with the developing bar-pool topography. Besides, sensitivity analyses indicate that, the shifting of bedload trajectory in the curved channel is not susceptible to particle size while considerably varies with flow discharge. Moving particles in a meandering channel are ultimately constrained within the belt of “concave bank‒crossing bar‒concave bank” after the bend topography is fully developed and the bed deformation reaches a dynamic equilibrium.