洋山港及邻近海域悬沙输运特征研究*

基于SWEM2D数值模型,建立了一个范围包括洋山港、长江口及杭州湾的二维水流泥沙数学模型。根据2004年5月洋山港实测水文泥沙资料,认为洋山港区域悬沙垂向切变输运较小,可忽略该项对悬沙输运的影响,采用二维泥沙数学模型能基本反映出该区域悬沙输运特点。利用2004年5月洋山港及邻近海域实测水文泥沙资料对模型计算结果进行验证,验证结果表明模型计算结果与实际情况吻合良好。在此基础上,根据模型计算结果计算了洋山港及邻近海域大、中、小潮期间悬沙输运速度。结果表明,洋山港区域悬沙主要以欧拉输运为主,斯托克斯漂移、潮泵输运为辅。该区域西口门高含沙量主要是受到长江口及杭州湾悬沙输运富集的影响。其邻近海域主要的悬沙输运在近南汇边滩以东区域分成两股,一股向北,一股沿着南汇南岸的水下泥沙通道,径直流向杭州湾,并在杭州湾的悬沙输运的带动下,向洋山港流去。

Characteristics of suspended sediment transport in Yangshan harbor and its adjacent areas

Based on the SWEM2D model, a 2D flow and sediment numerical model is built including Yangshan harbor, the Yangtze estuary and Hangzhou bay. The measured data observed from Yangshan harbor in May 2004 shows that the vertical shear of the suspended sediment plays such a small impact on its sediment transport that a 2D sediment numerical model can almost represent the sediment transport near Yangshan harbor.The model result is in good agreement with the measured data which observed from Yangshan harbor and its adjacent areas in May 2004. On that basis, a transport velocity of suspended sediment during the spring, middle and neap tide in the Yangshan harbor and its adjacent areas is calculated. The result shows that in the Yangshan harbor, the Euler transport plays predominant role in suspended sediment transport while the Stokes drift and tidal pump play secondary. The high concentration of suspended sediment in the west of the Yangshan harbor is mainly caused by the convergence of the sediment transport from the Yangtze estuary and Hangzhou bay. Near the east of Nanhui beach, the suspended sediment transport separates into two parts: one flows northward, the other, firstly,flows towards Hangzhou bay along the underwater sediment channel at the south of Nanhui beach and then flows to Yangshan harbor by the suspended sediment transport from Hangzhou bay.