[H-DS05] Landslides and related phenomena

[HDS05-06] A study of the debris flow event in Hongye Village, Taiwan - Based on iRIC Morpho2DH Analysis

★Invited Papers

*Zheng-yi Feng¹, Tien-Chun Hsu¹ (1.National Chung Hsing University)

Keywords:debris flow, numerical simulation, iRIC Morpho2DH, parametric study, runout distance

Typhoon Meranti in September 2016 brought abundant rain in Hongye Village, Taitung, Taiwan, triggering the upslope on the west side of the Hongye Village to slide and became a debris flow, causing damage and burial of houses downstream. The purpose of this study is to apply the iRIC Morpho2DH program to obtain a Baseline Case by back-analysis for the debris flow event in Hongye Village. The analyzed debris flow paths and impact areas were compared by the post-disaster aerial images. The accuracy of the simulations was judged by using the coverage index and the thickness of the debris flow at the accumulation zone. The optimized parameter combination of the iRIC Morpho2DH program was obtained after multiple iterations. In this study, the Baseline Case was used for parameter study. It is found that the ‘static deposition sediment concentration’, source volume of debris flow, and ‘liquid behavior sediment ratio’ are the most important parameters; while the internal friction angle and the mean grain diameter are less important. In order to explore the effectiveness of the post-event mitigation works, we assumed two landslide scenarios for further simulations to assess whether the impact area of future debris flows can be controlled.