Abstract
Flood-generated floating vegetation debris can accumulate near hydraulic structures, posing risks to power generation and engineering safety. Understanding the transport characteristics of different types of floating aquatic vegetation debris is fundamental for modeling their movement. A Lagrangian experiment was conducted in a laboratory straight water channel using six models of floating vegetation debris (categorized as leaf-type and rod-type) with varying shapes and sizes. The trajectories of the models were tracked and processed using image analysis technology, and diffusion coefficients were calculated based on distribution data. Results indicate that centimeter-sized models move at the same velocity as the surface flow. The diffusion coefficient in the flow direction was approximately twice that of the spanwise diffusion coefficient. The shape and size of the debris models influenced diffusion characteristics: leaf-type models diffused faster than rod-type models, while leaf-type models with a center of mass offset showed greater spanwise diffusion. Shorter models exhibited higher diffusion tendencies in the spanwise direction. Diffusion properties in the two directions vary significantly with flow conditions and debris model characteristics. Formulas were proposed for estimating dimensionless diffusion coefficients in both directions. These findings are valuable for predicting the potential accumulation zones of floating vegetation debris under varying flow conditions.