Experimental Study on Diversion Dike to Mitigate Debris Flow Blocking River Disaster

Barrier lakes formed by debris flows blocking rivers can burst rapidly, posing significant threats to downstream areas. Mitigating the risk of barrier lake breaches caused by debris flow blockages is crucial for ensuring safety in affected regions. This study employed physical experiments to investigate the influence of connection angles between the main flume and the tributary flume, as well as the installation of diversion dikes, on the morphological characteristics of debris flow deposits and the resulting barrier lake breach behavior. The findings reveal that when the debris flow enters the main flume at an intersection angle of 60°, compared to vertical entry (90°), the deposit’s height and volume are significantly reduced, while its length is increased. However, with the installation of a diversion dike, the height, volume, and length of the deposits are minimized, achieving the smallest values observed. Specifically, compared to vertical entry and a 60° connection angle without a diversion dike, the deposit volume decreased by 31.54~56.26%, height by 10.81~34.75%, and length by 2.33~25.05%. Post-breach observations indicate that the installation of a diversion dike results in the widest breach, the smallest peak flow, and the earliest occurrence of the peak flow. These findings demonstrate that diversion dikes effectively mitigate the barrier lake breach disaster caused by debris flow by altering the deposit morphology. The results provide valuable insights for the prevention and management of debris flow-induced river blockages and associated disasters in mountainous regions.