基于随机位移方法的河道植被区悬沙沉积分布计算模型  

Random Displacement Method-based Model for Predicting the Distribution of Net Sediment Deposition in Vegetated Channels

作　　者：李川[1] 孙思晨 单钰淇 刘永浩 刘超[1] LI Chuan;SUN Sichen;SHAN Yuqi;LIU Yonghao;LIU Chao(State Key Laboratory of Hydraulics and Mountain River Engineering,Sichuan University,Chengdu 610065;Institute for Disaster Management and Reconstruction,Sichuan University,Chengdu 610065)

机构地区：[1]四川大学山区河流保护与治理全国重点实验室,四川成都610065 [2]四川大学灾后重建与管理学院,四川成都610065

出　　处：《工程科学与技术》2025年第1期48-56,共9页Advanced Engineering Sciences

基　　金：国家重点研发计划政府间国际科技创新合作重点专项(2022YFE0136700);国家自然科学基金项目(52379072,52279072);四川省科技计划项目(2022NSFSC0969)。

摘　　要：天然河道中,水生植被影响水流特性与悬沙输移规律,使得河道植被区的悬沙沉积分布相比于无植被区更加复杂,模拟难度更高。为探究河道植被区悬沙沉积分布,本文将改进边界条件后的随机位移模型引入植被作用下的水沙输移研究,融合真实形态植被对水流特性的影响,提出了适用于真实形态植被(以芦苇为例)下的悬沙沉积分布计算模型。为验证计算模型的准确性,本文选用具有真实外形的仿真芦苇开展水槽试验,详细测量了不同泥沙粒径、水流条件和植被密度下的芦苇区悬沙沉积沿程分布。试验结果发现:泥沙粒径、上游平均流速和植被密度均影响河道芦苇区的悬沙沉积分布,其中,对植被区前端的悬沙沉积量影响尤为显著。植被区泥沙补给是否受限会导致悬沙沉积呈现两种截然不同的分布。本文提出的数值计算模型可较好地模拟泥沙补给不受限条件下河道植被区的悬沙沉积分布,模拟结果与试验结果的量级和变化趋势均吻合较好;但该模型不能捕捉泥沙补给受限条件下植被区的悬沙沉积分布。综上,本文提出的基于随机位移方法的计算模型可较准确地预测河道植被区的悬沙沉积沿程分布,但仅适用于植被区泥沙补给不受限的情况。In natural rivers,aquatic vegetation affects flow characteristics and suspended sediment transport patterns,resulting in a complex distribution 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 predict 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 influenced by particle size,upstream mean flow velocity,and vegetation density.Particularly,the diminished deposition occurs at the canopy’s leading 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 sediment supply is limited within vegetated regions.In conclusion,the proposed random displacement method-based numerical model accurately predicts the distribution of sediment deposition inside vegetated regions in open channels,provided the upstream sediment supply is not limited.

关 键 词：河道植被区 随机位移模型 仿真芦苇 悬沙沉积分布 

分 类 号：TV142[水利工程—水力学及河流动力学]