高含沙河口导堤丁坝算法的建立以及在长江口北槽的初步应用

This study is aimed to develop an unstructured-grid finite-volume three-dimensional dike-groyne algorithm, which is suitable for high-turbidity estuary with coupling effects of current, sediment and morphology, and to apply it on the North Passage of the Changjiang Estuary. Based on high-resolution unstructured-grid three-dimensional coastal ocean model (FVCOM), dike-groyne treatment algorithm for low-turbidity water and community sediment transport model (CSTM), an algorithm to treat the dike-groyne structures in the high-turbidity estuary is developed. This method not only reveals the two-layer current structure of upper free-exchange region and lower blocked area, but also has the capability of simulating the sediment transport near the dikes and their morphological responses, and the inverse influences of morphology changes on the hydrodynamics and sediment are also included in this model. The new algorithm cuold be widely applied to study the coupling effects of coast-defense dike, submegred dikes for reclamation, channel-regulation groynes and etc. The Changjiang Estuary is selected as an example to apply this new algorithm on the North Passage to make more accurate modeling of effects of the dikes and groynes on the hydrodynamics, sediment and bed morphology changes and the interaction mechanism among these dynamics.

本研究拟建立适用于高含沙量河口海岸区域流场－泥沙－地貌过程耦合的无结构三角网格有限体积三维导堤丁坝数值算法，并初步应用到长江口北槽区域。 在现有高分辨率无结构三角形网格三维河口海岸数值模型FVCOM、申请人所开发的适用于清澈水体或低含沙水体的导堤丁坝处理算法、全沙输运模型CSTM的基础上，建立适用于高含沙水体的导堤丁坝数值算法，不仅能刻画出导堤丁坝附近上层自由交换、下层阻挡的两层流场结构，还能合理模拟出导堤丁坝附近的泥沙输运及地貌响应，并反馈至流场的变化。该算法可以普遍应用在海岸防波堤、促淤围垦潜堤、航道丁坝等多种高含沙河口导堤丁坝结构。并选择长江河口作为例子，将该算法初步应用到北槽区域，以便能更加客观科学地描述长江口北槽深水航道整治工程中导堤丁坝对流场、泥沙输运、河床冲淤变化的影响以及它们之间的相互作用。

本研究基于FVCOM模型建立了适用于高含沙量河口海岸区域流场－泥沙－地貌过程耦合的无结构三角网格有限体积三维导堤丁坝数值算法，同时，在CSTM泥沙数值模型的基础上完善了细颗粒粘性泥沙动力过程，并初步应用到长江口北槽区域。该算法不仅能刻画出导堤丁坝附近上层自由交换、下层阻挡的两层流场结构，还能合理模拟出导堤丁坝附近的泥沙输运及地貌响应，并反馈至流场的变化。并选择长江河口作为例子，将该算法初步应用到北槽区域。并基于海洋遥感、现场观测和数值模型提出了一种估算长江口底部泥沙临界起动应力空间分布的方法，从而能够更加合理地提供长江口泥沙模拟的底部边界条件，以便能更加客观科学地描述长江口北槽深水航道整治工程中导堤丁坝对流场、泥沙输运以及它们之间的相互作用。