Rainfall and Geological Conditions for Debris Flow Occurrence

• Main Authors: Xu-Zhi Zheng, 鄭胥智
• Other Authors: Chyan-Deng Jan
• Format: Others
• Language: zh-TW
• Published: 2003
• Online Access: http://ndltd.ncl.edu.tw/handle/71823863075512453239

碩士 === 國立成功大學 === 水利及海洋工程學系碩博士班 === 91 === Rainfall is an element of triggering debris flow, and geological condition is the potential term. The previous researches on debris flow occurrence focused on the analysis of rainfall, without consideration of the geological conditions. Both rainfall and geological conditions were taken into consideration for the influence of occurrence of debris flow in this paper. Rainfall factors include of the hourly rainfall, the daily rainfall and the previous rainfall factors (one-week previous rainfall). Various combinations of the former three rainfall factors to establish a rainfall index , R, to evaluate the influence of rainfall. Geological factors content the watershed form, the mean slope of stream bed, the effective area of watershed, and the mean values of the combination property of the slope of hillside and the rock property. The former four geological factors were normalized, and then were combined into a geological index ,M . The propose rainfall index R and the geological index M are applied in evaluating debris flow potential of the watershed, Chenyoulen Stream. Each geological factor, against the rainfall index R is analyzed. The critical line were proposed for debris flow occurrence. Finally , we apply the upper limit of rainfall index of the non-bursting debris flow and the lower limit of comprehensive index of bursting debris flow to divide the possibility of bursting debris flow into three regions ,say the lower potential, the middle potential and the higher potential regions.