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.

Yan-fang Zhao;Jing-jing Fan;Wei-jie Wang;Han-qing Zhao;Fei Dong;Zhen Han;Shi-yan Wang

School of Water Conservancy and Hydroelectric Power,Hebei University of Engineering,Handan 056038,China;State Key Laboratory of Simulation and Regulation of Water Cycle in River Basin,China Institute of Water Resources and Hydropower Research,Beijing 100038,China;China Three Gorges Corporation,Wuhan 430010,China;National Engineering Research Center of Water Resources Efficient Utilization and Engineering Safety,Nanjing 210024,China

水动力学研究与进展B辑

[1]Yan-fang Zhao;Jing-jing Fan;Wei-jie Wang;Han-qing Zhao;Fei Dong;Zhen Han;Shi-yan Wang-.Dispersion features of pollutants in a compound channel with vegetated floodplains)[J].水动力学研究与进展B辑,2022(06):1095-1105

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