Effects of Extreme Rainfalls and Physiographic Factors on Landslide Number Magnitude and Magnitude-Frequency Relation for the Chenyulan Watershed in Central Taiwan

Abstract

The frequency-magnitude distribution of landslides in the Chenyulan watershed central of Taiwan has investigated comprehensively Landslide data was collected from three extreme rainfall events Typhoons Haitang Sinlaku and Morakot via the detection of Formosa Satellite Images with detailed field checking A total of 1 981 landslides were obtained from the three data sets which where mainly located in steep slope areas covered with forest land and range land Our results showed that the frequency-magnitude distribution of the landslides exhibits a power-law behavior indicate that the collapsing hill slope has Self-organized criticality in the Chenyulan watershed Moreover a total of 1 981 landslides were categorized into different groups based on physiographic factors (e g gradient elevation and land use) and discussed the power-law relations in each landslide group to understand the behavior and the complexity network of landslide occurrence Analysis of the landslide area and its corresponding probability density of landslide area showed that each physiographic and rainfall factors were connected and highly related with the landslide occurrence Soil and rock strength land use and rainfall condition has an important roles in the occurrence of landslide This study provided useful information in the assessment of landslide hazard and risk in advance

Date of Award	2014 Jul 7
Original language	English
Supervisor	Chyan-Deng Jan (Supervisor)