Flow and Sediment Characteristics in Meandering Branch Channel Under the Effects of Vegetation
Rivers,particularly meandering branching channels,play an essential role in human production,life,and the development of civiliza-tion.Their unique topography and complex flow and sediment transport characteristics significantly impact river stability,flood control,naviga-tion,and economic development along the coast.In meandering branching channels,the widening of diversion areas and the influence of bend cir-culation cause sediment to accumulate on the convex bank,forming shallow banks that raise vegetation growth.This process triggers solid bank formation,reduces flow velocity,raises water levels,and induces other effects.However,limited research has addressed meandering branching channels influenced by vegetation,and resolving the complex relationship between flow-sediment dynamics in these channels remains an urgent challenge.This study conducts generalized physical experiments to investigate the unsteady flow of meandering branching channels under vari-ous inflow conditions and vegetation densities.Flow and sediment data are collected using techniques such as ultrasonic distance measurement,video stream gauging,and instantaneous sediment transport rate measurement.The study analyzes the characteristics of water flow and sediment transport during the erosion and reconstruction processes of meandering branching channels influenced by vegetation.Key aspects include changes in branch diversion ratios,averaged bedload transport rates per unit width,and variations in the characteristic parameters of transported bedload.The experimental results showed that under unsteady flow conditions,the diversion ratio of the left branch channel is significantly af-fected by vegetation and tends to increase with higher vegetation density.In contrast,the diversion ratio in the right branch is more sensitive to the presence or absence of vegetation cover,while vegetation cover density has a lesser effect.Regarding bedload transport,vegetation in the branch channel increases the sediment transport rate and sediment grading.As vegetation density in the right branch increases,the peak bedload transport rate rises,and fluctuations in bedload transport become more pronounced,particularly at higher flow rates.In addition,changes in quantified para-meters of channel interactions reveal that the influence between channels during the reconstruction process intensifies significantly with the in-creased vegetation density in the branch channel.These findings provide theoretical support for channel regulation and river ecological restora-tion.
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