A new treatment of the exchange layer thickness to evaluate sediment sorting and armoring

Abstract

This study presents a new treatment of an exchange layer to evaluate the sediment sorting and armoring process. In this treatment, a thickness of bed load layer is evaluated as a function of bed shear stress, and is introduced into a well known exchange layer model which firstly proposed by Hirano (1971). The results predicted by the present method on sediment sorting, armoring and associated bed degradation accord with flume data. This suggests that sediment sorting and associated problems can be predicted well using an automatically determined thickness of bed -load layer, although the well known constant layer model can give good results on the problems under consideration if one determines the thickness properly by try and error.