Application of a Topography-Rainfall Combination Index in Assessing Spatial-Temporal Debris-Flow Occurrence Potential

  • 安 以欣

Student thesis: Master's Thesis


Debris flow occurrence is more frequent in central Taiwan because of its topographic and hydroclimatic characteristics GIS was used to identify the different characteristics of the 69 gullies which includes the catchment area stream gradient stream length elevation slope and the use of Inverse Distance Weight (IDW) for rainfall interpolation The purpose of this study is to determine the debris flow hazard quantitatively with the help of a combination index as well as topographical and rainfall factors The study area is Chenyulan watershed in Taiwan because of the numerous recorded debris flow occurrence and availability of rainfall data for the chosen period In July 2001 rainfall brought by Typhoon Toraji triggered a number of debris flow and caused many of casualties and property damages in the watershed The data of this rainfall event has been used in this study to determine the rainfall intensity and effective accumulated rainfall The 40-m DTM was used to determine the catchment area gradients elevation and stream length The result of the topographical and rainfall factors of the 69 gullies were mapped to determine the risk probability using the prediction factor conditions The relationship of T and R shows that 29% of the total gullies lies in the red zone or the high risk probability of debris flow occurrence Thus gullies with high topographical and rainfall factors are likely to have the higher the probability of debris flow occurrence
Date of Award2017 Feb 14
Original languageEnglish
SupervisorChyan-Deng Jan (Supervisor)

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