杭州湾沉积物宏观输运的数值模拟

用Delft3D模拟了杭州湾水动力和粘性沉积物输运过程,探讨了沉积物宏观输运和地貌演变的物理机制。忽略波浪作用,假设底质均一,不考虑粘性沉积物的底部固结作用,建立杭州湾粘性沉积物输运的数值模型。计算结果显示,模型能够反映杭州湾沉积物输运的宏观规律,再现了杭州湾悬沙浓度分布"三高两低"的特征、水体和沉积物"北进南出"的输运格局以及杭州湾总体上受控于淤积的地貌演变过程。杭州湾的沉积物输运主要受浅水分潮潮波变形引起的潮汐不对称性控制,该区潮波自东南向西北的传播方向、舟山群岛对涨潮流的阻隔效应、杭州湾喇叭形态的约束作用等因素造成"北进南出"的水沙输运特征。杭州湾与欧洲斯凯尔特河口狭长型的河口的沉积物输运路径有明显差异。

Modelling macro-scale suspended sediment transport patterns in Hangzhou Bay, China

Based on exact calculation of tidal currents,the present contribution models the suspended sediment transport patterns in the Hangzhou Bay.The model is validated with field observations.The model results reproduce the distribution characteristics of suspended sediment concentration(SSC) in the Hangzhou Bay with three high SSC zones and two low SSC zones,the flow and sediment transport patterns associated with landward transport in the north and seaward transport in the south,and the sediment accretion in most parts of the Hangzhou Bay.The model results agree with previous studies which were mainly based on field observations with various temporal and spatial scales.Similar to most estuaries in the world,the sediment transport in the Hangzhou Bay is controlled by tidal asymmetry induced by tidal wave distortions.In addition,local characteristics of hydrodynamics and bathymetry,influenced by the combination of the propagation direction of tides from the northwest Pacific Ocean,hindering of flood currents by the Zhoushan Archipelogo and the funnel-shaped geometry of the bay,play an important role in generating the sediment transport patterns.