Laboratory Analysis of Debris Flow Characteristics and Berm Performance

Kukhyun Ryou,Hyungjoon Chang,Hojin Lee

doi:10.3390/w13162223

Abstract

In this study, laboratory tests were used to determine the deposition characteristics (runout distance, lateral width, and deposition area) of debris flow and their relationships with the flow characteristics (flow velocity and flow depth) according to the presence of a berm. An experimental flume 1.3 to 1.9 m long, 0.15 m wide, and 0.3 m high was employed to investigate the effects of channel slope and volumetric concentration of sediment with and without the berm. The runout distance (0.201–1.423 m), lateral width (0.045–0.519 m), and deposition area (0.008–0.519 m2) increased as the channel slope increased and as the volumetric concentration of sediment decreased. These quantities also increased with the flow velocity and flow depth. In addition, the maximum reductions in the runout distance, lateral width, and deposition area were 69.1%, 65.9%, and 93%, respectively, upon berm installation. The results of this study illustrate general debris flow characteristics according to berm installation; the reported relationship magnitudes are specific to the experimental conditions described herein. However, the results of this study contribute to the design of site-specific berms in the future by providing data describing the utility and function of berms in mitigating debris flow.

Highlights

In this study, laboratory tests were used to determine the deposition characteristics of debris flow and their relationships with the flow characteristics according to the presence of a berm
The reported debris flow velocity v, flow depth h, and Froude number Fr were measured by Chang et al [4]; the runout distance R, lateral width B, and deposition area A were measured in this study
We focused on debris flow in urban areas using a berm as a debris flow mitigation measure

Summary

Introduction

Laboratory tests were used to determine the deposition characteristics (runout distance, lateral width, and deposition area) of debris flow and their relationships with the flow characteristics (flow velocity and flow depth) according to the presence of a berm. The runout distance (0.201–1.423 m), lateral width (0.045–0.519 m), and deposition area (0.008–0.519 m2 ) increased as the channel slope increased and as the volumetric concentration of sediment decreased. These quantities increased with the flow velocity and flow depth. Debris flow is a mass movement toward downstream areas along a flow path under the influence of gravity, and can be a mixture of water, clay, soil, gravel, rock, boulder, and timber [3,5,8] It can be caused by various factors, such as heavy rainfall, typhoons, snowmelt, earthquakes, volcanoes, and human activities [9,10].

Methods

Results

Discussion

Conclusion