珠江口黄茅海枯季的悬沙变化与泥沙输运

Spatiotemporal variations of suspended sediment concentration and sediment transport during a dry season in Huangmaohai Estuary,Pearl River Delta

基于2010年3月的观测数据,结合数值模型,分析了珠江口黄茅海悬沙的时空变化,计算了全潮及枯季一个月平均的悬沙通量。结果表明:枯季时黄茅海内的悬沙变化深受河口的流速不对称、内潮不对称的影响,大多数站位都呈现出悬沙含量涨潮高于落潮的现象。受到径流、潮汐、密度环流、局地地形的影响,在河口湾的东槽内出现多个泥沙汇聚的滞流点。通过模拟2010年2-3月枯季时的泥沙输运过程,表明在湾口的岛屿间形成复杂的泥沙输运涡旋。枯季时西口为泥沙向陆输运的通道,而中口与东口则以向海输运为主。东槽内的泥沙输运发生向陆与向海方向的多次转变。

Based on the measurement data in March, 2010, combined with numerical simulation, this study on studying the spatiotemporal variations of suspended sediment concentration in the Huangmaohai Estuary focuses , Pearl River Delta. The tidally and monthly averaged sediment transport fluxes are calculated based on surveyed data and model results, respectively. The results show that the variations of the sediment concentration are greatly impacted by the asymmetries of velocity and vertical water mixing. The sediment concentrations at most stations were ob- served to be higher during flood tides than ebb tides. Affected by the river inflow, tides, baroclinic circulation and local bathymetry, there develop several stagnant points （or convergence points） along the East Channel. Through simulation of sediment transport in February and March, 2010, it is revealed that there exist complex sediment transport eddies around the islands in the mouth of the estuary. The West Passage acts as a sediment import chan- nel, while the Middle and East Passages are sediment export waterways. The sediment transport direction in the East Channel experiences landward and seaward changes alternately.