Random Displacement Method-based Model for Predicting the Distribution of Net Sediment Deposition in Vegetated Channels
In natural rivers,aquatic vegetation affects flow characteristics and suspended sediment transport patterns,resulting in a complex distri-bution of sediment deposition inside canopies compared to bare channels.The distribution of in-canopy deposition is challenging to simulate.This study examines the distribution of suspended sediment deposition in vegetated regions within open channels.The improved random displacement method is introduced to model water and sediment transport under the influence of emergent vegetation.In addition,a model is proposed to pre-dict the distribution of suspended sediment deposition,specifically applicable within emergent vegetation canopies with real plant morphology(reeds).To verify the numerical model,sediment sizes,mean channel velocities,and plant densities are analyzed to evaluate the distributions of net deposition inside canopies with realistic morphology.Results indicated that the distribution of sediment deposition inside canopies is influ-enced by particle size,upstream mean flow velocity,and vegetation density.Particularly,the diminished deposition occurs at the canopy's lead-ing edge.The deposition patterns exhibit two distinct behaviors under varying sediment supply conditions in vegetated areas.The comparison between the predicted and measured deposition distributions demonstrates that the proposed numerical model provides an accurate simulation of deposition distribution when the upstream sediment supply is not limited to vegetated regions.The magnitude and trend of the model simulations align with experimental results.However,the model does not precisely calculate the distribution of sediment deposition when the upstream sedi-ment supply is limited within vegetated regions.In conclusion,the proposed random displacement method-based numerical model accurately pre-dicts the distribution of sediment deposition inside vegetated regions in open channels,provided the upstream sediment supply is not limited.
vegetated channelrandom displacement modelsimulated reedssediment deposition distribution
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