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The alteration of lateral circulation under the influence of human activities in a multiple channel system, Changjiang Estuary
Estuarine, Coastal and Shelf Science ( IF 2.8 ) Pub Date : 2020-05-16 , DOI: 10.1016/j.ecss.2020.106823
Yu Chen , Qing He , Jian Shen , Jiabi Du

Extensive coastal engineering activities including channel dredging and constructions of large infrastructure have greatly altered hydrodynamics in the Changjiang Estuary. While the changes in longitudinal circulation have been well-documented, limited studies have focused on the alteration in lateral circulation and its impact on estuarine circulation in the Changjiang Estuary. Lateral circulation in an estuary plays an important role in modulating estuarine circulation, sediment transport, and morphological change. Different from many of previous numerical studies, we utilize an unstructured-grid numerical model configured in a way to allow inundation over dikes and tidal flats. Numerical model experiments show significant changes in lateral circulation and stratification along the North Passage in response to the altered geometry and bathymetry due to the channel deepening and the dike construction. Both the channel deepening and the dike construction led to an enhanced stratification. Further analysis suggests that the along-channel, the lateral, and the vertical (including up- and downwelling and vertical mixing) effects are all important in modulating the intra-tidal stratification-destratification process. The channel deepening enhances both the lateral and the vertical effects around the high-water slack. The construction of dikes that completely blocks the lateral water exchange between the North Passage and surrounding tidal flats, changes the system from a multiple-channel system into a single-channel system. With dike construction, the estuarine circulation tends to have a horizontally sheared pattern with weaker friction and a stronger stratification.



中文翻译:

长江口多通道系统中人类活动影响下的侧向循环变化

广泛的海岸工程活动,包括航道疏and和大型基础设施的建设,极大地改变了长江口的水动力。尽管已经很好地记录了纵向环流的变化,但有限的研究集中在侧向环流的变化及其对长江口河口环流的影响上。河口的横向循环在调节河口循环,泥沙输送和形态变化中起重要作用。与以前的许多数值研究不同,我们利用非结构网格数值模型,该模型配置为允许在堤坝和滩涂上淹没。数值模型实验表明,由于河道加深和堤防构造的改变,几何形状和测深法改变了沿北通道的横向循环和分层的显着变化。航道的加深和堤防的建设都增强了分层。进一步的分析表明,沿河道,横向和垂直(包括上井和下井以及垂直混合)的影响在调节潮汐内分层-消结过程中都非常重要。航道的加深增强了高含水松弛周围的横向和垂直效应。堤坝的建造完全阻止了北通道与周围的滩涂之间的侧向水交换,从而将系统从多通道系统转变为单通道系统。

更新日期:2020-05-16
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