TWO LAYER MODEL FOR ANALYSIS OF DEPOSITION AND EROSION PROCESSES OF DEBRIS FLOWS

Abstract

Present study deals with deposition-erosion process of debris flow with transition between fully dispersed debris flow and sediment sheet flow. A two layer is derived to unify these two kind of flows. An “interface” is introduced between upper layer which is mainly consist of water and lower layer which is mainly consist of sediment. This model consists of mass and volume conservation of water and sediment including an equation describing level change of immobile bed as well as momentum equation of the both layer. Numerical analyses were carried out to explain experiments of deposition-erosion process of debris flow and sediment sheet flow on the rigid or movable bed. Calculated results agree well with experimental data for wide range of condition.