Typhoon Morakot brought tremendous rainfall to southern Taiwan. It caused many villages and towns to be flooded in low-lying areas as well as numerous landslides and debris flows in mountainous areas. Therefore, the disaster resulted in severe casualties and property damage. This paper presents a case study of Ji-Lou landslide triggered by Typhoon Morakot. A series of hydrogeological investigations, insite tests, and laboratory experiments were carried out to establish the hydrogeological conceptual model of Ji-Lou landslide. Coupled analysis of rainfall, infiltration, seepage, slope stability, and slope deformation was used to estimate the slope stability of Ji-Lou landslide during Typhoon Morakot. For the active landslide analysis, a twodimensional numerical program, GeoStudio, was employed to perform the modeling practice. The results show the F.S. of Ji-Lou landslide reduced from 1.57 to 0.97 during Typhoon Morakot. In addition, the results of coupled analysis demonstrated good agreement between the predicted results and the data from field monitoring of the typhoon event. Further, it is expected the landslide initiation, enlargement, and reactivation can be more confidently predicted through using the aforementioned physics-based models.
Taiwan is an active mountain belt created by the oblique collision between the northern Luzon arc and the Asian continental margin. The inherent complexities of geological nature create numerous discontinuities through rock masses and relatively steep hillside on the island. In recent years, the increase in the frequency and intensity of extreme natural events due to global warming or climate change brought significant landslide and debris flow hazards. In 2009, a comprehensive survey was conducted on landslides caused by Typhoon Morakot in southern Taiwan. Typhoon Morakot caused many villages and towns to be flooded in low-lying areas as well as numerous landslides and debris flows in mountainous areas. Therefore, the disaster resulted in severe casualties and property damage.
