Multi-scale landslide susceptibility analysis along a mountain highway in Central Taiwan

• The landslide susceptibility was analyzed in catchment scale and local scale.
• Rainfall in the future was predicted by the atmospheric general circulation model (AGCM).
• This study aims to study the landslides along the mountain highway Nantou County Road #89 of Taiwan.
• The pros and cons of the analysis in catchment scale and local scale were discussed.
• The results of this study could be applied for the risk assessment and management.

For the past decade, climate change has caused increasingly more frequent extreme rainfall events in Taiwan, during which concentrated and intense rainfall has induced large-scale flooding and landslides. Considering the urgency of protecting isolated villages and residential areas near highways from large-scale landslides, this study analyzed landslide susceptibility along Nantou County Road #89, in the upstream region of the Wu River in Taiwan. To assess landslide hazards spatially, landslide susceptibility analysis was implemented at the catchment scale. To predict landslide susceptibility, this study employed an atmospheric general circulation model with downscaling estimation. Information from boreholes was used to analyze the temporal behavior and complex mechanisms of large-scale landslides at the local scale. On the basis of the results, this paper discusses the different findings from the catchment- and local-scale analyses. For the major large-scale landslides, the rankings of landslide susceptibility values can be obtained to prioritize the remediation of the landslides. And the multiscale landslide susceptibility analysis could be applied to mountain highways with complex landslide hazard.