Dynamic environment in the Ta-Chia River watershed after the 1999 Taiwan Chi-Chi earthquake

The 1999 Chi-Chi earthquake (Mw = 7.6) induced a tremendous number of landslides in Central Taiwan, and about 1.5 million m3 of earth was driven from broken slopes in the Ta-Chia River watershed. The impact of this earthquake not only made the geomaterial more fractured, but also changed the river morphology of the Western Foothill area. The main purpose of this study was to investigate the dynamic environment of the Ta-Chia River watershed after the 1999 Chi-Chi earthquake. The study comprised three major parts: a landslide inventory, a landslide analysis, and a time effect study. A conceptual model was developed to investigate the time effect of the earthquake impact on the landslide–rainfall correlation. The study focused on the major typhoon events after the 1999 Chi-Chi earthquake, including Toraji (2001), Mindulle (2004), and Sinlaku (2008).