Establishing Landslide Susceptibility Along a Coastal Range Highway in Eastern Taiwan

Typhoon Megi (2010) had brought intense rainfall and hit the northeastern part of Taiwan. It caused a widespread rock fall, debris slide, rock slide, and debris flows along highway Route 9. The multi-hazard susceptibility map based on logistic regression approach and rock mass rating system (RMR) was adopted to evaluate the landslide susceptibility in this study. Firstly, the multi-hazard susceptibility model categorized the hazard potential for different geological hazards into low, moderate, and high level. Secondly, the study performed a geomechanical classification system for rocks according to field investigation along the vulnerable road section. The result reveals that a semi-quantitative hazard matrix combining with the both evaluations can assess the geological hazard appropriately. In addition, the high-resolution DEM extracted from airborne LiDAR and multi-temporal remote sensing images had been analyzed to examine the morphological change and geological structure for the landslide location with a high susceptibility. Finally, the detailed landslide susceptibility with three levels on highway is proposed and verified.