Analytical Solution of Suspended Sediment Concentration Profile: Relevance of Dispersive Flow Term in Vegetated Channels. Issue 7 (21st July 2020)

• Record Type: Journal Article
• Authors: Huai, Wenxin; Yang, Liu; Guo, Yakun
• Is Part Of: Water resources research. Volume 56:Issue 7(2020)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2020-07-21
• Subjects: dispersive flow -- double‐averaging method -- suspended sediment concentration -- vegetated open channel flows; Hydrology -- Periodicals; 333.91
• DOI: 10.1029/2019WR027012
• Languages: English
• ISSNs: 0043-1397

Abstract

Abstract: Simulation of suspended sediment concentration (SSC) has great significance in predicting the sediment transport rate, vegetation growth, and the river ecosystem in channels. The present study focuses on investigating the vertical SSC profile in the vegetated open channel flows. To this end, a model of the dispersive flux is proposed in which the dispersive coefficient is expressed as partitioned linear profile above or below the half height of vegetation. The double‐averaging method, that is, time‐spatial average, is applied to investigate the vertical SSC profile in the vegetated open channel flows. The analytical solution of SSC in both submerged and emergent vegetated open channel flows is obtained by solving the vertical double‐averaging sediment advection‐diffusion equation. The morphological coefficient, a key factor of dispersive coefficient, is obtained by fitting the existing experimental data. The analytically predicted SSC agrees well with the experimental measurements, indicating that the proposed model can be used to accurately predict the SSC in the vegetated open channel flows. Results show that the dispersive term can be ignored in the region without vegetation, while the dispersive term has significant effect on the vertical SSC profile within the region of vegetation. The present study demonstrates that the dispersive coefficient is closely related to vegetation density, vegetation structure, and stem Reynolds number but has little relation with flow depth. With a few exceptions, the absolute value of the dispersive coefficient decreases with the increase of vegetation density and increases with the increase of stem Reynolds number in the submerged vegetated open channels. Key Points: A dispersive model is proposed to investigate the sediment transport in the vegetated open channels with parameters fitted with experiments Analytical solution of the vertical suspended sediment concentration profile is derived for submerged and emergent vegetated open channels The effects of dispersion on suspended sediment concentration in the vegetated channels is demonstrated by the double‐averaging method