A modified leading-edge runout model incorporating the flow regimes of debris flows.

Debris flows pose great threats to people's safety and cause catastrophic damage to infrastructure. Accurate prediction of debris flow runout distance provides a scientific basis for delineating hazard zones and formulating disaster mitigation countermeasures. As a analytical model, the leading-edge model is widely used to predict debris flow runout distance in practice. The flow regime determines the stress state of the debris flow, which ultimately affects the debris flow runout distance. Particle collision stress, Coulomb friction stress, and viscous stress are three common stresses in debris flows. However, only the effect of Coulomb friction is considered in the leading-edge model. In this study, a modified debris flow runout distance model incorporating the effects of particle collision, Coulomb friction, and viscous drag is established. This study innovatively introduces the Bagnold number and Savage number into the runout distance model to establish the link between micro and macro variables, which provides a new approach for predicting the debris flow runout distance. The modified model is also validated and analyzed based on data from flume experiments and actual debris flow events. The results show that the modified model performed well in predicting debris flow runout distance. In addition, this study provides an open-ended discussion of the factors affecting debris flow runout distance and the shortcomings of the modified model, thus providing a basis for further study in the future. [ABSTRACT FROM AUTHOR]