Simulation of the entire generation process of post-fire debris flows at Ren’e Yong gully in China

The generation of post-fire debris flows has been shown to significantly differ from that of non-fire related debris flows, particularly in terms of erosion patterns and response to rainfall, necessitating further research on the complete hazard generation process. To explore this phenomenon, a post-fire debris flow event at Ren’e Yong gully in China was analyzed using simulations conducted with OpenLisem. This approach enabled the consideration of multiple factors within the simulation, including rainfall interception, soil infiltration, surface runoff, erosion, channel incision, bank slope erosion, and subsequent landslides. The results showed as follows: i)Overland flow initiated more rapidly and intensely in burned areas compared to unburned ones, and it also diminishes more quickly as rainfall decreases; ii)Surface erosion increases with the severity of the burn, leading to greater channel erosion in areas with larger burned extents; iii)The erosion phase of post-fire debris flow can be categorized into four stages: initial rainfall splattering, surface erosion and channel initiation, enhanced channel erosion during the debris flow process, and channel bank slides. This simulation successfully replicates the entire process of post-fire debris flow generation, demonstrating how increased surface runoff and erosion in burned areas contribute to the formation of debris flows.