LATERAL AND LONGITUDINAL SEDIMENT SORTING IN SERI RIVER, JAPAN

The present study investigates the lateral and longitudinal sediment sorting and an equilibrium channel pattern in the Seri River, Japan by means of numerical simulations. To discuss such sediment transport processes, we employ two methods. One is the bedload formula with its functional form of τ*1.5 as well as with a constant exchange layer thickness. The other with its functional form of τ*2.5 as well as with bedload layer thickness instead of constant exchange layer. Herein, τ* is the non-dimensional bed shear stress. Results of the numerical simulations suggest that the sediment sorting is influenced by the choice of bedload formula and that sediment sorting takes place actively in the case of computation with the bedload formula with τ*2.5. The computed results are agreed with the data obtained from field observations.