LATERAL SEDIMENT TRANSPORT OF HETEROGENEOUS BED MATERIALS

Abstract

Longitudinal and lateral transport rates of uniform sediment and heterogeneous mixtures are measured experimentally with a laterally inclinable wind tunnel, and the sediment transport rates are formulated in terms of Shields stress, critical Shields stress and lateral inclination angle. The critical Shields stress of uniform and heterogeneous materials in air flow are observed to be much smaller than those in water flow. The critical shear velocity for each fraction size of heterogeneous mixtures does not depend on the size, which indicates that the incipient motion of sediment in air flow is the impact threshold. The amount of sediment transport in air flow increases at very large rate against Shields stress in the vicinity of the critical Shields stress. The ratio of lateral sediment transport to longitudinal one for heterogeneous mixtures is found to depend on the sediment size, because larger sizes feel the lateral gravitational force more than the finer ones.