边滩植被对复式河道水动力特性的影响

The Influence of Riparian Vegetation on the Hydrodynamic Characteristics of Compound Channel

天然河道的滩地上广泛上存在着不同类型的植物,其存在对河道的水动力特性的影响受到了广泛的关注。基于Delft 3D软件,建立了复式河道边滩植被水流的数值模型,并以植被直径、高度、密度和生长位置为控制变量,研究这些变量对复式河道植被区纵向水面坡度、充分发展处垂向平均的纵向流速横向分布、和滩槽纵向流速偏差比等水动力特性的影响规律。结果表明,植被直径、高度和密度的增加都显著改变了纵向流速横向分布;滩槽纵向流速偏差比、水面坡度与植被直径为二次曲线关系、与植被高度为线性关系、与植被密度为对数关系;边滩和主槽内的水面坡度差异随着植被直径、高度和密度的增加;植被不对称生长会导致主槽区最大流速位置偏移。

The influence of different vegetations widely habituating on the floodplain of natural rivers on the hydrodynamic characteristics of compound channel has always been concerned.This study has established a numerical model of riparian vegetation flow of compound channel based on Delft 3D software,and adopted the diameter,height and density of vegetation as control parameters,to investigate the influence of these parameters on the longitudinal water surface slope,lateral profile of depth-averaged longitudinal velocity,and the ratio of difference of velocities in main channel and flood plain to the average velocity of whole cross section.Research indicate that the increase in diameter,depth and density of vegetation changes the lateral profile of longitudinal velocity significantly.The ratio of difference velocity and the water surface slope are correlated with the diameter of vegetation quadratic,with the height of vegetation linearly,with the density of vegetation log⁃arithmically.The difference between water surface slopes of main channel and flood plain increase as long as the increase in diameter,height and density of vegetation;and the maximum velocity in the main channel is shifted due to the imbalance distribution of vegetation.