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Dispersion features of pollutants in a compound channel with vegetated floodplains

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Abstract

The planting of the vegetation on the floodplain helps the ecological restoration, which is the main form of the river’s ecological corridor. Therefore, the current research of the river dynamics focuses on the water movement under a compound channel with the vegetated floodplains. Two simulated vegetation species are selected in this paper for the flume simulation experiments of the floodplain vegetation, and the compound channel is divided into three subregions in the transverse direction. The Navier-Stokes equation and the eddy viscosity theory are applied to obtain the transverse distribution of the depth-averaged velocity and the results agree well with the experimental data. This paper proposes a new method based on the analytical solution of the flow velocity distribution to calculate the average flow velocity in each section. Calculation results can effectively simulate the average flow velocity of the measured sections. The description of the pollutant transport processes in a moving stream requires a refined determination of the dispersion coefficients in the compound channel. The process of the pollutant concentrations in each zone and the reasons for their occurrence are elucidated on the basis of the experimental results. Simultaneously, the measured values of the longitudinal dispersion coefficients are obtained by the “routing procedure,” and a two-zone model of the pollutant dispersion is constructed on the basis of the hydrodynamic study. The prediction method for the longitudinal dispersion coefficients is also presented. Applying the predicted and measured section average flow velocities to the two-zone model to predict the longitudinal dispersion coefficient, and the average relative errors are only 4.17%, 7.15%, respectively. This result indicates that the two-zone model can effectively predict the longitudinal dispersion coefficients. The calculation methods for the longitudinal dispersion coefficients from—various studies are compared. The results reveal that the predicted values of these calculation methods are all larger than the measured values, indicating that the vegetation has a considerable influence on the dispersion process. This study comprehensively shows the dispersion features of the pollutants and provides a theoretical basis for the planning and the design of the vegetated ecological corridors.

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Acknowledgements

This work was supported by the Research project of China Three Gorges Corporation (Grant No. 202103399), the Talent Program of China Institute of Water Resources and Hydropower Research (Grant No. WE0199A052021) and the Basic Scientific Research Expense Project of IWHR (Grant No. WR0145B022021).

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Authors and Affiliations

  1. School of Water Conservancy and Hydroelectric Power, Hebei University of Engineering, Handan, 056038, China

    Yan-fang Zhao & Jing-jing Fan

  2. State Key Laboratory of Simulation and Regulation of Water Cycle in River Basin, China Institute of Water Resources and Hydropower Research, Beijing, 100038, China

    Yan-fang Zhao, Wei-jie Wang, Fei Dong, Zhen Han & Shi-yan Wang

  3. China Three Gorges Corporation, Wuhan, 430010, China

    Han-qing Zhao

  4. National Engineering Research Center of Water Resources Efficient Utilization and Engineering Safety, Nanjing, 210024, China

    Han-qing Zhao

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  1. Yan-fang Zhao
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  2. Jing-jing Fan
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  3. Wei-jie Wang
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Correspondence to Wei-jie Wang.

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Ethical approval: This article does not contain any studies with human participants or animals performed by any of the authors.

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Conflict of Interest: The authors declare that they have no conflict of interest.

Informed consent: Informed consent was obtained from all individual participants included in the study.

Project supported by the National Key Research and Development Program of China (Grant No. 2019YFD1100205), the National Natural Science Foundation of China (Grant Nos. 51809286, 52209083, 51809288, 41501204 and U1802241).

Biography: Yan-fang Zhao (1996-), Male, Master

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Zhao, Yf., Fan, Jj., Wang, Wj. et al. Dispersion features of pollutants in a compound channel with vegetated floodplains. J Hydrodyn 34, 1095–1105 (2022). https://doi.org/10.1007/s42241-023-0084-1

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  • DOI: https://doi.org/10.1007/s42241-023-0084-1

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