The blockage and erosion characteristics of woody debris flow on an erodible gully bed: Insight from a small-scale model experiment.

This article focuses on the blockage behavior and characteristics of woody debris flow in narrow channels, based on laboratory experiments considering factors such as the relative length (L/B) and content (Vl/Vc) of large wood (LW), debris flow bulk density, and channel slope. The study identifies three blockage types—non-blockage, semi-blockage, and blockage—and finds that blockage degree increases with LW size and content but decreases with slope, while also influencing sediment erosion and deposition patterns. An improved blockage criterion F is proposed, integrating LW characteristics, sediment concentration, and slope to better evaluate blockage risk, with temporary blockage likely when F ranges from 1.5 to 5.0 and stable blockage occurring below 1.5. The research highlights the importance of considering woody debris in debris flow hazard assessments and notes limitations due to laboratory conditions, suggesting future work to include more complex natural gully dynamics and mitigation strategies.