STUDY ON LOCAL SCOUR AND VARIATION OF BED COMPOSITION AROUND NON-SUBMERGED SPUR DYKE

Abstract

Several studies have been made on local bed scour by movable bed experiments. Researches taking into account non-uniform sediment transport are still very few, in particular in case of the involvement of spur dykes. In this paper, we carried out movable bed experiments around an impermeable spur dyke under non-submerged condition. Both uniform and non-uniform sediment beds with similar mean diameter used and the changes of the bed configuration and bed surface composition have been considered. In addition, we used color sediment which is divided in three ranges of diameter with different colors in order to clarify the spatial differences of bed surface composition through pictures and visual observation. We focused on the relation between initial grain-size distribution and the final scour hole depth and the influence of vortices around a spur dyke on bed surface composition.