Lateral flows redistribute sediment and influence the morphodynamics of channel‐shoal systems. However, our understanding of lateral transport of suspended sediment during high and low water slack is still fairly limited, especially in engineered estuaries. Human interventions such as dike‐groyne structures influence lateral exchange mechanisms. The present study aims to unravel these mechanisms in a heavily engineered, turbid channel‐shoal system in the Changjiang Estuary, using a high‐resolution unstructured‐grid three‐dimensional model and in situ observations. Analysis of model results reveals two typical transport patterns during slack‐water conditions, that is, shoal‐to‐channel transport during low water slack and channel‐to‐shoal transport during high water slack. A momentum balance analysis is carried out to explain mechanisms driving the lateral transport of suspended sediment during high water slack, revealing the importance of lateral pressure gradients, Coriolis force, and the curvature‐induced term. Groyne fields play a crucial role in sediment transport, especially during low water slack. A model scenario in which one groyne is removed reveals that groyne fields strongly influence lateral sediment transport. The decomposition of the sediment transport flux reveals that the turbidity maximum is shaped by a balance between seaward advection by residual flows, and landward transport by tidal pumping and gravitational circulation. Within the turbidity maximum, sediment is laterally redistributed by lateral flows during slack‐water conditions, greatly influencing estuarine channel morphology.

中文翻译：

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潮汐-渠道-汇流系统中泥沙输送的研究：侧向效应和松弛水动力学

横向流动重新分配沉积物并影响河道-浅滩系统的形态动力学。然而，我们对高水位松弛和低水位松弛期间悬浮沉积物的侧向运输的理解仍然相当有限，尤其是在工程河口中。堤防结构等人为干预会影响横向交换机制。本研究旨在利用高分辨率的非结构网格三维模型和原位观测资料，在长江口一个经过精心设计的，浑浊的渠道-浅滩系统中阐明这些机制。对模型结果的分析揭示了在缺水条件下的两种典型的输运模式，即低缺水时的浅滩到河道输运和高缺水时的浅滩到河岸输运。进行了动量平衡分析，以解释在高水松弛期间驱动悬浮泥沙横向输送的机理，揭示了侧向压力梯度，科里奥利力和曲率诱发项的重要性。yne地在沉积物的运输中起着至关重要的作用，特别是在低水位松弛期间。去除一个防波堤的模型场景表明，防波堤场强烈影响横向沉积物的运输。泥沙输送通量的分解表明，最大浊度是由残余流向海平流与潮汐泵送和重力循环向陆输送之间的平衡所决定的。在最大浑浊度范围内，在闲水条件下，泥沙因侧向流动而在侧面重新分布，从而极大地影响了河口河道的形态。