A new rainfall Intensity-Duration threshold curve for debris flows using comprehensive rainfall intensity

Rainfall plays a crucial role in triggering debris flows, and the rainfall Intensity-Duration (I-D) threshold curve is widely used in early warning systems for debris flows and landslides. However, this model has a notable limitation: it cannot differentiate between rainfall processes with different peaks when the rainfall duration and average rainfall intensity of two rain events are the same. To address this limitation, we proposed the concepts of energy rainfall intensity (Ie) and comprehensive rainfall intensity (Ic) for the first time. By combining Ie, maximum rainfall intensity (Im) and average rainfall intensity (I) in different ways, we constructed a comprehensive rainfall intensity-duration threshold curve (Ic- D). By simulating the differences in peak discharges produced by different rainfall processes using the SCS hydrological model, we explored the superiority of the new rainfall intensity parameters. This newly-developed threshold curve improves the accuracy in predicting debris flow occurrences, reducing false alarms and missed alarms by 23 % compared to a traditional I-D approach, and holds importance for improving early warning models in predicting debris flows.