Local scour at a trapezoidal abutment: sediment motion pattern

Abstract

Results for a local scour experiment are presented where the sediment motion was measured around a trapezoidal abutment. The experiment was performed in clear-water conditions. The sediment fluxes were evaluated by measuring the concentration and the velocity of the moving particles. Various evolution stages were considered, from the start of the experiment to a scour depth of almost twice the abutment length, with particular focus on the temporal and spatial evolution of the sediment kinematics. The results are then compared systematically with literature studies on the vortical flow field around trapezoidal abutments, to verify the consistency between the observed liquid and solid phase motion fields in a local scour process. The findings may support phenomenological analysis of the erosion process and numerical modeling of the temporal development of the scour depth at a trapezoidal abutment.