Characteristics and Causes of the Debris Flow in Shelong Gully, China

A rainfall-induced debris flow disaster occurred in Shelong Gully on the 22th June, 2019. More than 26,300 m² of farmland and 14 houses were buried and transportation and power supply broke down in the worst catastrophe in the history of Shelong area. To investigate this disaster, a detailed interpretation was carried out using (Unmanned Aerial Vehicle) UAV-based images. Analysis of disaster characteristics based on images and field survey revealed that the disaster could be identified as a consequence of compound mountain hazards including mass movements and mountain torrent in Shelong Gully. Moreover, the dynamic process of debris flow was analysed by using the finite difference method. Its dynamic characteristics indicated that the structure of debris materials changed during the movement process of debris flow. The results reveal that the loose materials, steep terrain condition and abundant rainfall are the main causal factors of this disaster event. This research on the analysis of hazard formation conditions and dynamic process for debris flows is of guiding significance to the formulation of disaster risk assessment and disaster mitigation plans.