Roles of barrier location for effective debris flow mitigation: assessment using DAN3D

Abstract

Debris flows can travel at rapid velocities and can cause economic and societal damages. Accordingly, barriers that can dissipate the energy of debris flows are frequently installed as a mitigation measure. However, the effect of barriers on debris-flow behavior is not fully understood. In this study, we used DAN3D to investigate the interactions between a debris flow and barriers, and evaluate the effect of barrier location on debris-flow velocity and volume. We chose a study site in Seoul, Korea, where a debris- flow event occurred in 2011. At the site, we numerically installed a closed-type barrier at four different locations along the flow path in the watershed. We then simulated the debris flow while monitoring debris-flow velocity and volume. The barriers decreased the velocity and volume of the debris flow compared to a simulation with no barrier. In particular, installation of the barrier at the upstream portions of watersheds resulted in the greatest reduction in velocity. Installation of the barrier at downstream portions of watersheds resulted in the greatest deposition of volume. These results contribute to a better understanding of debris-flow behavior associated with the installed barriers as a mitigation measure, and can be used for optimum and efficient design of the debris-flow barriers.