Field observations of debris-flow initiation processes on sediment deposits in a previous deep-seated landslide site

作     者：Fumitoshi IMAIZUMI Satoshi TSUCHIYA Okihiro OHSAKA 

作者机构：Department of Environment and Forest Resources ScienceFaculty of AgricultureShizuoka University 

出 版 物：《Journal of Mountain Science》 (山地科学学报（英文）)

年 卷 期：2016年第13卷第2期

页      面：213-222页

核心收录：

学科分类：081803[工学-地质工程] 0709[理学-地质学] 0819[工学-矿业工程] 08[工学] 0303[法学-社会学] 0818[工学-地质资源与地质工程] 0708[理学-地球物理学] 0705[理学-地理学] 0815[工学-水利工程] 0706[理学-大气科学] 0816[工学-测绘科学与技术] 0813[工学-建筑学] 0704[理学-天文学] 0833[工学-城乡规划学] 0713[理学-生态学] 0834[工学-风景园林学（可授工学、农学学位）] 

基　　金：supported by the Grant-in-Aid for Scientific Research of Japan Society for the Promotion of Science (JSPS KAKENHI) (Grant Nos.80378918 26292077) 

主　　题：滑坡泥石流 现场观测 堆积过程 地下水位上升 河道沉积 孔隙流体 泥石流滑坡 视频摄像头 

摘      要：Although information regarding the initiation processes of debris flows is important for the development of mitigation measures,field data regarding these processes are scarce.We conducted field observations of debris-flow initiation processes in the upper Ichinosawa catchment of the Ohya landslide,central Japan.On 19 June 2012,our videocamera monitoring systems recorded the moment of debris-flow initiation on channel deposits(nine surges) and talus slopes(eight surges).The initiation mechanisms of these surges were classified into three types by analyzing the video images: erosion by the surface flow,movement of deposits as a mass,and upward development of the fluid area.The first type was associated with the progress of surface flow from the upper stream on unsaturated channel deposits.The second type was likely caused by an increase in the pore water pressure associated with the rising in the groundwater level in channel deposits;a continuous water supply from the upper stream by the surface flow might have induced this saturation.The third type was associated with changes in the downstream topography caused by erosion.The flow velocity of most surges was less than 3 m s^(-1) and they usually stopped within 100 m from the initiation point.Surges with abundant pore fluid had a higher flow velocity(about 3- 5 m s^(-1)) and could travel for alonger duration.Our observations indicate that the surface flow plays an important role in the initiation of debris flows on channel deposits and talus slopes.