Dynamic characteristics and erosion effect of a landslide-induced debris flow which occurred in Pingwu, southwest China

This paper puts the research of dynamic characteristics and erosion effect of the landslide-induced debris flow a step further based on the Xiangbizui (XBZ) debris flow which occurred in southwest China. Firstly, based on the in-site investigation, remote sensing, and unmanned aerial vehicle (UAV) aerial photography, we revealed that the continuous heavy rainfall directly induced the debris flow, and the steep terrain enhanced the destructive power. Then, the Voellmy-Salm model was utilized to reveal the dynamic characteristic of the XBZ landslide-induced debris flow. The Coulomb friction coefficient μ and the viscous turbulence coefficient ξ calibrated by three previous debris flows in XBZ gully were 0.25 and 320 m/s, respectively. Furthermore, an empirical erosion model was employed to reproduce the erosion and entrainment process on the debris flow gully, and the erosive rate is − 0.013 m/s. The maximum velocity of sliding mass was about 18.29 m/s, and the maximum flow depth was about 10.34 m. The flow height, velocity, and affected area were controlled by the topography and erosion on channel materials. The total volume of runout material obviously increased because of the erosion and entrainment. Furthermore, there was a quadratic function relationship between the released volume and the eroded volume. The research results are helpful to the quantitative risk assessment of the debris flow with erosion and entrainment in mountainous area.