As a result of the geological weakness in Taiwan, the landslides often occur during heavy rainfall. Consequences of landslides can be serious silting in reservoirs, mudslides to destroy building and facilities, and escalating economic losses. Assessment on landslide potential in the watershed by heavy rainfalls has been successfully analyzed by the physical and numerical model. However, phenomena on landslides induced by the pressure in unsaturated porous media or the impact of rainfall-runoff process have not yet been appropriately predicated. Therefore, this study is to establish a two-dimensional, high-resolution model focused on rainfall-triggered unsaturated landslide in limited region with consideration on rainfall infiltration, surface runoff, and the variation of pore pressure in both saturated and unsaturated soil.
The study will be fulfilled in three years. This report presents results of the second year. By following the work content, the key of the study is focused on the development of two-dimensional rainfall-triggered unsaturated landslide model. According to the collection of past study, framework of the model is proposed, including the concepts of overland flow, saturated and unsaturated infiltration and landslides. After the developed model is verified, the influence of parameters and rainfall characters are then examined. Finally, apply the models to landslides in Yufeng subcatchment of Taiwan Shihmen reservoir watershed, the results of analysis show that area and depth of slope failure are fitted to the comparison results of DEM data. In addition, the information of study region is added to this study, and the effect of uncertain parameters about landslide potential in the past study is compared. About the diversities of landslide potential region, the in-situ test is applied to it. The location and tested data can be used for further analysis of two-dimensional landslide potential.