THREE-DIMENSIONAL STRUCTURE OF GRAVELS MOVING AS BEDLOAD AMONG BOULDERS

Abstract

 In this study, we investigated three-dimensional structure of gravels among boulders. The riverbed material consists of three groups of sediment grain sizes: boulders which cannot move at all, gravel which can move as bedload, and fine sand as suspended load. We conducted experiments focusing on the influence of the difference in grain size distribution of gravel on its structure. We measured the three-dimensional coordinates of gravel located in the riverbed surface layer as precisely as possible. As a result, it was clarified that there was no difference in the distribution of particles in the longitudinal and transverse direction, and occurrence probability decreases as the distance between particles with the maximum particle size increases.