Key Laboratory of Integrated Regulation and Resource Development on Shallow Lakes of Ministry of Education, College of Environment, Hohai University, Nanjing 210098, China; Yangtze Institute for Conservation and Development, Hohai University, Jiangsu 210098, China.
Key Laboratory of Integrated Regulation and Resource Development on Shallow Lakes of Ministry of Education, College of Environment, Hohai University, Nanjing 210098, China; Department of Civil and Environmental Engineering, National University of Singapore, 1 Engineering Drive 2, Singapore, 117576, Singapore.
J Environ Manage. 2023 Apr 15;332:117421. doi: 10.1016/j.jenvman.2023.117421. Epub 2023 Feb 4.
Turbulence generated within the vegetated confluence system is important for water quality and river management. In this study, we conducted a series of experiments to explore the extent to which emergent rigid vegetation in the confluence channel influences hydrodynamic characteristics and contaminant transport. First, a series of tests with increasing discharge ratios (from 0.35, 0.5, and 1) was conducted to quantify the effects of the discharge ratio on hydrodynamic conditions within the vegetated confluence. Then, tests with different discharge ratios were also set up to explore how contaminants released locations and modes (line and point source) influence the transport and mixing of contaminants. The results showed that increasing the discharge ratio induced larger momentum in the confluence area. The increase in discharge ratio rendered the circulation stronger, and its position came earlier in the non-vegetative area. In addition, the dimensionless turbulent kinetic energy peaked near the interface of the non/vegetated zone. With the increase in the discharge ratio, the dimensionless turbulent kinetic energy was found to be smaller. In the contaminants transport tests, the results revealed larger discharge ratio could speed up contaminants transport and mixing. The applications from this study would be helpful to pollutant transport management in natural confluences.
植物丛生交汇区内部生成的紊流对水质和河流管理很重要。在这项研究中，我们进行了一系列实验，以探究交汇通道中出露刚性植被在多大程度上影响水动力特性和污染物输运。首先，进行了一系列增加流量比（0.35、0.5 和 1）的测试，以量化流量比对植物丛生交汇区水动力条件的影响。然后，还设置了不同流量比的测试，以探究污染物释放位置和模式（线源和点源）如何影响污染物的输运和混合。结果表明，增加流量比会在交汇区引起更大的动量。流量比的增加使得环流更强，在非植物区的位置更早出现。此外，无量纲湍流动能在无/植物区界面附近达到峰值。随着流量比的增加，无量纲湍流动能减小。在污染物输运测试中，结果表明较大的流量比可以加速污染物的输运和混合。这项研究的应用将有助于天然交汇区的污染物输运管理。
