Satofuka, Y. et. al. Paper: Prediction of Floods Caused by Landslide Dam Collapse

Landslide dam formation and deformation strongly affect water and sediment runoff. When a large-scale landslide dam collapses due to overflow erosion, peak flood discharge may exceed inflow discharge by sev-eral times. Such an abrupt flow discharge increase by a dam burst may cause serious damage downstream. We propose a one-dimensional model for river-bed variation and flood runoff consisting of a two-layer model for immature debris flow and a bank erosion model. We applied this model to the Nonoo landslide dam in Japan’s Miyazaki Prefecture, formed by ty-phoon Nabi in September 2005, and China’s Tangji-ashan landslide dam formed in the Wenchuan earth-quake in May 2008. The model reproduces the ob-served flood runoff processes in the two areas. Calcu-lated results suggest that peak flood discharge dimin-ishes when water accumulating behind the landslide dam is small, and excavating the landslide dam crown effectively reduces flood discharge