Dynamic Process Modeling and Innovative Tertiary Warning Strategy for Weir-Outburst Debris Flows in Huocheng County, China

In China, weir-gully-type debris flows pose severe threats to transportation infrastructure, yet existing studies lack systematic analysis of their dynamic processes and early-warning strategies. This study innovatively integrates depth-integral modeling and field monitoring to investigate two unstable weirs upstream of the Zangyinggou Tunnel on the G30 Saiguo Expressway. The main research conclusions are as follows: (1) the influence of terrain and water source conditions on the weir-valley debris flow plays a dominant role; (2) the debris flows triggered by Weir I and II collapses reach the G30 Saiguo Expressway at 3560 s and 4000 s, respectively, with peak destructive capacities (cross-sectional sweep areas of 10.26 m2/s and 11.69 m2/s); (3) a three-level early-warning strategy was proposed, mainly based on water-level gauge monitoring and early warning, supplemented by video surveillance and regular measurement by small unmanned aerial vehicles. This study has established a brand-new idea for the monitoring and early warning of debris flow disasters induced by the collapse of barrier lakes along the G30 km line in Xinjiang. These achievements provide feasible insights for disaster reduction in mountainous transportation corridors, thus having significant practical value for promoting the sustainable development of infrastructure under the United Nations Sustainable Development Goals (SDGs).