No abstract

In the Ta-Chia River catchment, large numbers of landslides were induced by the 1999 Chi-Chi earthquake (M-w = 7.6), during which about 1.5 x 10(6) m(3) of earth was driven from broken slopes. The impact of this earthquake not only increased fracturing of the bedrocks but also changed the river morphology of the Western Foothills area. The main purpose of this study is to investigate the correlation of catchment sedimentation and landslides before and after the 1999 Chi-Chi earthquake. The study comprises two major parts: the preparation of databases of landslide inventory and catchment sedimentation and analyses of the correlation of catchment sedimentation and landslides. A conceptual model is developed to investigate the control factors of catchment sedimentation. Multi-variable analysis was applied to study the impact of landslides, triggered by the typhoons Herb (1996), Toraji (2001) and Mindulle (2004), on sediment production and sediment transportation