Landslide Susceptibility and Conservation Benefit Assessment for Chi-Sun watershed

• Main Authors: Pei-Shan Tsai, 蔡培珊
• Other Authors: 詹勳全
• Format: Others
• Language: zh-TW
• Published: 2015
• Online Access: http://ndltd.ncl.edu.tw/handle/72146439752574861895

碩士 === 國立中興大學 === 水土保持學系所 === 103 === In this study a multivariate analysis method, Logistic regression, was used for landslide susceptibility analysis of Chi-Sun watershed. After the extraction and selection of environmental factors, the elevation, slope, terrain roughness, slope roughness, NDVI, wentness index, and accumulated rainfall were selected as causal factors of initiating landslides. By inspecting the distributions of landslides resulted from Typhoon Morakot, it is found that the landslides are located in medium-high and high susceptibility area of the midstream and upstream watershed. And the overall accuracy in this event is 72.4%. The predicted susceptibility values show a good agreement with the observed landslides. It indicates that the model and factors used in this model are valid and the simulation results match the Typhoon Morakot event. In addition, the information on the past NDVI values obtained by the analysis of SPOT-4 images suggests a good vegetation recovery in the watershed landslides except the midstream and upstream areas. Therefore, this study focuses on providing suitable conservation and planning strategies around the small catchment of midstream watershed. Landslide hazardous areas are analyzed and mapped resulting from vegetation recovery for different situations. The result is that vegetation recovery to landslide susceptibility values greater impact in the study area when the return period from 50 to 100 years.