中文摘要：

洋山海域自2002年建港工程以来,先后封堵了北岛链三个过水汊道,使得海域附近水动力结构发生显著变化。采用工程前后大量水动力实测资料,并结合数值计算结果,对洋山海域工程前后的水动力特征进行了综合分析。研究结果表明：工程后大部分海域涨潮流速降低,但小洋山前沿除外;整个海域落潮流速度增加,但地形急剧缩窄的东口门区域增幅并不显著。讨论认为,地转偏向力显著增强了海域北部区域特别是小洋山前沿海域的涨潮流速,是小洋山岛屿前沿海域涨潮流速工程后维持不变的重要原因;受南岛链不规则岸线的影响,地转偏向力对落潮流影响不显著。工程后各汊道的封堵使得落潮流外泄不畅而发生壅水,使得工程后涨潮时段海域水位低于工程前,没有壅水现象发生。工程后的涨、落憩流时段均形成了较大范围、较长时段的弱流场。

英文摘要：

Started from October, 2002, the project of Yangshan Harbor is based on the Northern island chain by closing three main fork channels. Hydrodynamics are influenced significantly in this sea area due to this large-scale project. The observation data from several ADCP transects during October, 2002 and October, 2008 indicated that, the speed of tidal current during flood period decreased in the whole sea except near the Xiaoyangshan Island. The speed of tidal current during ebb period increased in the whole sea, but the variation range of velocity is not as significantly as that of topography changing in the eastern Yangshan Sea. To study these hydrodynamic phenomena and their variation characteristics before and after the project, five ADCP transects with seven measurements of current data in the sea were collected. In addition, a numerical model developed from FVCOM（Finite Volume Coastal Ocean Model） was applied in this sea to reproduce the situations before the project. Our results suggest that, the decrease of tidal current during flood period was mainly resulted from the decrease in flood tidal volume after the fork-closure project. However, the western flood current near the Xiaoyangshan Island was deflected to northward on the effect Coriolis force, thus the flood current near that island showed a slight increase after the project. Furthermore, the numerical experiment indicated that, the Coriolis force exerted little influence on the ebb currents, probably due to the irregular island lines on the south island chain. Since the outlet over the eastern sea dramatic converged after the project, the ebb current increased. However, the convergence of the eastern outlet also induced an occurrence of dammed water, causing a relative small increasing range of ebb velocity after the project. It should be noted that, the water level would rise up in the area near the Xiaoyangshan Island, mainly caused by the encounter of two strong flood currents. During flood period, the water level in the whole sea area after pro