STUDY ON THE VALLEY BEDS AND BANKS EROSION BY DEBRIS FLOWS

Abstract

 It is important to view erosion of valley beds and banks by debris flows not only as an instantaneous and localized process of change, but also as a phenomenon with a spatiotemporal extent. By considering debris flow erosion from an energetic viewpoint, it is possible to consider the erosion mechanism on a spatiotemporally extensive scale. In this study, we investigate the erosion mechanism of valley beds and banks erosion from the viewpoint of the three-dimensional equations of motion, based on detailed three-dimensional numerical experiments on a debris flow. Next, the hydraulic quantities obtained from the three-dimensional equation of motion are used to examine the mechanism of valley beds and banks erosion on a large scale from the viewpoint of energy transport. The results of the study indicate that the valley banks erosion is caused by debris flows with large longitudinal and transverse energy gradients striking the valley banks.