Evaluation of rainfall-induced large-scale landslide potential using Scoops3D

Taiwan is located in the Pacific volcanic seismic zone and frequently suffers from landslides and debris flow caused by typhoons. On average, there are four typhoons which may cause tremendous disasters such as massive landslides in Taiwan mainly from July to September every year. The aim of this study is to evaluate the development of large-scale landslide area under various cumulative rainfalls. The study area of this study is Liouquei, Kaohsiung in southern Taiwan. Firstly, the relationship of rainfall and groundwater level were built. The equation of change of groundwater level and rainfall is h=38.2R, R²=0.83. Then, 10m digital elevation model (10m-dem) was used to evaluate elevation, slope, aspect and etc. Finally, geology and 10m-dem were used to build Scoops3D model of Liouquei area.

Scoops3D, which is released by the United States geological survey (USGS), evaluates slope stability throughout a digital landscape represented by a digital elevation model (DEM). The program uses a three-dimensional (3D) method of columns limit-equilibrium analysis to assess the stability of many potential landslides (typically millions) within a user-defined size range. We simulated the potential landslide area under a cumulative rainfall in 24 hours from 800mm~1600mm. The results show that landslide area contributed 65%~76% of the entire potential large-scale landslide area.