Assessing landslide characteristics in a changing climate in northern Taiwan

This study analyzed landslide characteristics under extreme precipitation with regard to present and future scenarios, in order to analyze the effects of climate change on landslide activities. For our study area, we selected two adjacent catchments in northern Taiwan: the Shihmen Reservoir catchment, an area with high-relief topography that is susceptible to landslides at present, and the Xindian River catchment, an area with gentle topography that is not prone to landslides at present. This study established empirical relationships between landslide-area characteristics and rainfall conditions according to rainfall-induced landslides during past typhoon events. The relationships were applied to estimate landslide-area characteristics caused by typhoon events for the base period (1979-2003) and the end of the 21st century (2075-2099) according to the climate change scenario of representative concentration pathways 8.5 (RCP8.5) and dynamical downscaling of rainfall data in Taiwan. We also analyzed rainfall amounts at different recurrence intervals from different rainfall durations for the two catchments. We found that the area with high-relief topography (the Shihmen Reservoir catchment) is relatively prone to landslides currently and that the cumulative rainfall is a key factor controlling landslide-area characteristics. On the other hand, the area with gentle topography (the Xindian River catchment) is less prone to landslides at present, and the rainfall intensity is a key factor controlling landslide-area characteristics. Under the effects of climate change in the near future, both landslide severity and landslide frequency will increase more in areas with gentle topography than in areas with high-relief topography, in response to the more frequent occurrence of a strong typhoon with higher rainfall intensity.