Case Study: Effect of Submerged Aquatic Plants on Turbulence Structure in a Lowland River
Case Study: Effect of Submerged Aquatic Plants on Turbulence Structure in a Lowland River
复制标题
DOI：
10.1061/(asce)hy.1943-7900.0000195
复制
发表时间：
2010-07
影响因子：
2.4
通讯作者：
A. Sukhodolov;T. Sukhodolova
中科院分区：
文献类型：
--
作者：
A. Sukhodolov;T. Sukhodolova
水生植物与河流系统中湍流的相互作用引起了人们极大的兴趣。尽管描述理想化实验室流中植被与流相互作用的理论最近取得了进展，但由于对河流中自然形成的植被镶嵌体中异质（斑驳）分布的植物所造成的影响的了解有限，其实际应用仍然存在问题。本文报告了一项低地河流的研究，旨在量化和参数化植被对水流平均和湍流特征重新分布的影响及其对水力阻力的影响。这些测量是在夏季对一条河段进行的，河段上有一片片状的马赛克，主要是沉水的柔性水生植物，并在早春植物开始生长之前在相同的水位上重复测量。这项研究的设计允许定量评估在河床粗糙度元素（沉积物颗粒和沙坝）的可比淹没下，流动植物相互作用对总体流动参数造成的影响。研究表明，无植被河床中对称的准二维明渠水流结构转变为由马赛克中的斑块和自由路径空间排列的高度碎片化的复杂水流模式。尽管流动具有复杂性和三维性，但斑块中的归一化平均速度剖面可以通过双曲正切函数令人满意地描述，而自由路径中的流动（与无植被河道类似）与传统对数定律相当一致。
Interactions of aquatic plants with turbulent flows in fluvial systems have attracted considerable interest. While there have been recent advances in theories that describe vegetation-flow interactions in idealized laboratory flows, their practical application is still problematic due to limited knowledge of effects caused by heterogeneously (patchy) distributed plants in naturally formed vegetative mosaics in rivers. This paper reports on a study in a lowland river, aimed at quantification and parameterization of vegetation effects on redistribution of mean and turbulent characteristics of the flow and their consequences for hydraulic resistance. The measurements were carried out in summer on a river reach with a patchy mosaic dominated by submerged flexible aquatic plants and repeated at the same water level in early spring before the plants start growing. This design of the study allowed for quantitative evaluation of the effects caused by flow-plants interactions on bulk flow parameters at comparable submergences of riverbed roughness elements (sediment grains and sand bars). The study indicates that symmetrical quasi-two-dimensional open-channel flow structure in unvegetated riverbed was transformed into highly fragmented complex flow pattern spatially arranged by patches and free paths in the mosaic. Despite complexities and three dimensionality of the flow, normalized mean velocity profiles in the patches were satisfactory described by hyperbolic tangent function while flow in the free paths, similarly to unvegetated channel, was in a reasonable agreement with the conventional logarithmic law.