SEDIMENT SORTING IN SUSPENDED SEDIMENT DOMINATED RIVERS

Abstract

 Present study discusses the sediment sorting process of suspended sediment and bed-load layers based on a new method to describe the suspended sediment transportation. The sediment sorting is inferred to be caused by the coupled phenomena from the entrainment of bed-load layer to the suspended sediment layer and by particle settling from the suspended sediment layer to the bed-load layer, and the mass conservation equation is proposed for each sediment particle size in the flow with suspended sediment as well as in the bed-load layer. Then, we selected the Sen River, which flows into the Tonle Sap Lake, as one of the suspended sediment dominated rivers, and presented survey data on bed material in the channel reach, which confirmed that the sediment sorting of riverbed materials is caused by the proposed process. Besides, it is derived that the grain size distribution of the channel bed surface layer is determined by the setlling process of sediment particles constituting the suspended load.