Abstract

Background

Aquatic vegetation has major influence on the local water environment, affecting flow velocities and solute mixing. Extensive research has been conducted on the flow characteristics of vegetated areas, but little is known about solute transport. In this study, Laboratory experiments were carried out to investigate how solute transport is affected by emergent and submerged rigid vegetation.

Results

Vegetation greatly reduces the mean velocity, especially within the vegetated region. Near the bottom, the solute concentration is greater in the dense vegetation than in the sparse vegetation. The vertical distribution of the solute concentration decreases rapidly with the relative water depth. Generally, the longitudinal and lateral diffusion coefficients are less affected by denser vegetation, but both coefficients are strongly influenced by the relative water depth (submerged vegetation height).

Conclusions

A modified function to estimate the longitudinal diffusion coefficients is proposed under both emergent and submerged vegetation conditions, including cases of variable vegetation height. The key parameters (a’ and b’) for the assessment of the lateral diffusion coefficients are improved considering vegetation height. Results in the present paper can be used as efficient and convenient methods to estimate the longitudinal and lateral diffusion coefficients in flow with rigid vegetation.

中文翻译：

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刚性植被流中溶质运移的纵向和横向扩散

摘要

背景

水生植被对当地水环境有重大影响，影响流速和溶质混合。关于植被区的流动特性已经进行了广泛的研究，但对溶质的运输知之甚少。在这项研究中，进行了实验室实验，以研究溶质运移如何受到新兴和淹没的刚性植被的影响。

结果

植被大大降低了平均速度，特别是在植被区域内。在底部附近，浓密植被中的溶质浓度大于稀疏植被中的溶质浓度。溶质浓度的垂直分布随相对水深而迅速减小。通常，纵向和横向扩散系数受密度较高的植被影响较小，但两个系数均受相对水深（淹没植被高度）的强烈影响。

结论

提出了一种在突发和淹没植被条件下估计纵向扩散系数的修正函数，包括可变植被高度的情况。考虑到植被高度，改进了用于评估侧向扩散系数的关键参数（a'和b'）。本文的结果可作为一种有效而方便的方法来估算刚性植被流动中的纵向和横向扩散系数。