Author(s): Haruyuki Hashimoto; Hiroki Takaoka; Kichan Park
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Abstract: Relatively coarse sediments are carried as bed load at gentle slopes and move as debris flow when at steep slopes. At the intermediate slopes, however, two-layer flow appears; the lower layer is denser fluid of sediment-water mixture and the upper layer almost clear water. On the other hand, Cohesionless fine sediments are carried as bed and suspended loads at gentle slopes and move as mud flow when at the steep slopes. At the intermediate slopes, however, higher concentration of bed and suspended loads appear. This type of sediment transport is discussed in the present study. We use a two-layer model of granular and inertial sublayers. Regarding the top of the lower layer as the reference level, the concentration profiles are calculated from the Rouse equation. Concentration in the lower layer is obtained from the momentum equation. Velocity profile formulas are also derived from the momentum equation for each layer. From these results sediment discharge formula is derived. The sediment discharge formula is compared with the measurements and is found appropriate for the various types of sediment transport.
Year: 2004