Debris-Flow Hazard Assessment Considering Dynamic Characteristics Index with High-Resolution Topography in Duoxiongla Valley (China)

Debris-flow hazard assessment is essential for identifying the hazard levels of individual gullies and supporting regional disaster prevention and mitigation. Conventional approaches mainly evaluate potential debris-flow magnitude and intensity based on indicators such as catchment area, historical activity, and relative elevation difference, while dynamic-process information during debris-flow movement is often insufficiently represented. Although process-based hazard assessment has been widely used for individual gullies or specific scenarios, a regional framework that systematically integrates multiple simulated dynamic parameters across numerous gullies remains limited. In this study, the Duoxiongla Valley on the southeastern margin of the Tibetan Plateau was selected as the study area. Based on high-resolution remote sensing data, including 0.5 m orthophoto imagery and 5 m airborne LiDAR data, dynamic numerical simulations were conducted to reproduce debris-flow movement processes. Key parameters, including flow depth, flow velocity, and affected area, were extracted and integrated using the entropy weight method to construct a dynamic characteristics index (DCI). The novelty of this study lies in systematically constructing the DCI for 47 debris-flow gullies and embedding it into a conventional weighted hazard-assessment framework, thereby linking numerical simulation outputs with regional multi-gully hazard classification. The DCI-based hazard-assessment results show that high- and very-high-hazard debris-flow gullies account for 10.64% of the total gullies and are mainly distributed in the middle and upper reaches of the study area. Compared with the traditional assessment method, the introduction of the DCI resulted in hazard-level adjustments for six debris-flow gullies, which were consistent with the actual hazard conditions. These differences mainly reflect the limited ability of conventional indicators to represent debris-flow movement intensity and spatial impact. Specifically, some gullies with large catchment areas exhibit limited spatial expansion due to topographic constraints, whereas some small-catchment gullies may still show high hazard levels due to large elevation differences, high flow velocity, large flow depth, or extensive affected areas. These results demonstrate that integrating multi-parameter dynamic-process information can refine regional debris-flow hazard classification and provide a transferable framework for identifying dynamically hazardous gullies in high-relief mountainous regions.