To investigate the effects of stratification,flocculating settling,and sediment available for resuspension on the morphology of the maximum turbidity zone(MTZ)in the North Passage(NP)of the Changjiang River Estuary(CRE),a numerical simulation study was conducted utilizing a three-dimensional flow-salinity-sediment coupling model specific to the CRE.The findings indicate that turbulence suppression caused by suspended sediment can further enhance water column stratification,which is already influenced by salinity-induced turbulence suppression,thereby establishing a distribution pattern characterized by high concentrations of near-bottom sediment.The upper section of the NP experiences less impact from saltwater intrusion compared to its middle and lower sections;consequently,this results in relatively weaker stratification-a significant factor contributing to the uniform vertical distribution of suspended sediment observed in this region.Additionally,variations in flocculating settling velocity exhibit notable vertical and longitudinal changes within the NP,leading to distinct influences on the vertical distribution patterns of suspended sediment within the MTZ along different segments of the channel.The non-uniformity in sediment available for resuspension throughout the NP accounts for why there is no strong correlation between suspended sediment concentration(SSC)in the maximum turbidity zone and flow velocity.An increase in sediment available for resuspension not only elevates overall SSC levels within the MTZ but also intensifies vertical trapping effects through its influence on both stratification and flocculating settling processes,thereby enhancing high-concentration near-bottom sediment distributions.
关键词
长江口北槽/最大浑浊带/数值模拟/层化作用/絮凝沉降/可悬浮泥沙量
Key words
North Passage of Changjiang River Estuary/turbidity maximum zone/numerical simulation/stratification effect/flocculation settling/sediment available for suspension
维普
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