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长江口北槽最大浑浊带形态影响因素数值模拟研究

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为了探明层化、絮凝沉降和可悬浮泥沙量对长江口北槽最大浑浊带形态的影响,基于长江口三维水流、盐度、泥沙耦合模型对三种影响因素开展数值模拟研究.研究结果表明:悬沙制紊可以在盐度制紊基础上进一步加强水体层化作用,促进形成近底高浓度泥沙分布形态.北槽上段受盐水入侵影响小于中下段,层化制紊作用相应较弱,这也是北槽上段悬沙垂向分布较为均匀的重要原因;泥沙絮凝沉速在北槽断面呈现显著的垂向和纵向变化,对最大浑浊带悬沙垂向分布形态影响也具有较明显的沿航道变化特征;悬浮泥沙量沿北槽不均匀分布是造成最大浑浊带含沙量与沿程流速没有良好对应关系的原因,可悬浮泥沙量增加不仅可以提高最大浑浊带整体含沙量,并且可以通过影响层化以及絮凝沉降加强泥沙垂向捕集作用,促进近底高浓度泥沙分布形态.
Numerical simulation and analysis on influencing factors of turbidity maximum zone in the North Passage of Changjiang River Estuary
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.

North Passage of Changjiang River Estuaryturbidity maximum zonenumerical simulationstratification effectflocculation settlingsediment available for suspension

华厦、张磊、徐岢

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南京水利科学研究院,南京 210029

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

国家重点研发计划项目南京水利科学研究院中央级公益性科研院所基本科研业务费专项资金项目南京水利科学研究院中央级公益性科研院所基本科研业务费专项资金项目长江科学院开放研究基金资助项目

2017YFC0405400Y222006Y223002CKWV20221007/KY

2024

水道港口
交通部天津水运工程科学研究所

水道港口

CSTPCD
影响因子：0.348
ISSN：1005-8443
年,卷(期)：2024.45(5)