岛群区峡道潮流切变锋及其泥沙输运特征研究

Tidal Shear front are common and persistent features in many tidal channels of group of islands. Front and lateral shear flow circulation will greatly affect the associated sediment transport processes, and it has important significance for morphology，pollutants dispersion of the tidal channels and so on. This phenomenon has caused widespread concern, but lacking of comprehensive research for the islands area. In the background of the development of the island, tidal front as a common phenomenon in tidal channel, the research on the tidal front and the impact of tidal front on the sediment transport will be the guide factor affecting the development of the island's port waters. Based on field observations, combining with the methods of numerical simulation, and theoretical analysis, the flow velocity and suspended sediment concentrations of the frontal zone in tidal channels of Zhoushan Islands during the whole tidal cycle are studied. At the same time, the impact of topography and tidal current on frontal zone structure, circulation structure and suspended sediment transport is researched. The mechanism of the frontogenetical shear front, structure of the circulating current and sediment transport characteristic of frontal zone will be revealed. And the research result could provide a scientific basis for the development of the island harbor waters.

岛群区峡道中普遍存在潮流切变锋现象，潮流切变锋及其伴生的横向环流会极大影响所处水域的水动力条件和泥沙输运过程，同时对峡道地貌演变、污染物扩散等也有显著影响。在“建设海洋强国”的背景下，海岛建设势在必行，潮流切变锋作为影响岛群区峡道内水动力和泥沙输运的重要因素，对海岛临港海域开发具有重要的指导意义和研究价值。本项目拟对潮流切变锋作用下岛群区峡道内的水动力和泥沙输运特征进行深入研究，选取舟山群岛典型潮流峡道为研究区域，采用实地观测、数值模拟和理论分析的方法，明确潮流切变锋在潮周期各阶段中的演变过程，及其相对应的锋区环流和泥沙浓度变化情况，并分析地形、潮流等因素对锋区结构、锋区环流以及泥沙输运特征的影响。项目预期将揭示潮流切变锋锋生机理、以及在潮流切变锋作用下岛群区峡道内的三维水动力和泥沙输运特征，项目的研究成果对于峡道地区的悬沙输移、地形演变等具有重要意义，可为海岛临港海域的建设提供科学依据。

岛群区峡道中普遍存在潮流切变锋现象。潮流切变锋以及伴生横向环流会极大影响泥沙输运过程，同时对海岛近岸地貌演变、污染物扩散、动植物生长环境等也有显著影响。切变锋的这一现象已引起广泛关注，但目前针对岛群区潮流切变锋的研究相对较少。本项目以舟山群岛典型潮流峡道——虾峙门峡道作为研究对象，采用实地观测、数值模拟、理论分析的方法，研究潮流切变锋锋区的水动力结构、温盐结构和泥沙结构，分析潮流切变锋的锋生锋消变化规律，阐明虾峙门峡道潮流切变锋主要为流向切变锋和流速切变锋，流向切变锋发生在转流阶段，流速切变锋发生在涨落潮阶段，锋生位置基本在浅滩边缘，锋线平行于等深线，同时，根据锋区的温盐结构在有无锋面时变化不大的规律，以及对虾峙门峡道浅滩深槽的潮流分析，再结合前人对于切变锋锋生机制的研究，得到虾峙门峡道潮流切变锋锋生机制为滩槽水体的流速、流向差导致的正压梯度力。