钱塘江河口悬沙输运特征及影响机制

Characteristics of Suspended Sediment Transport in Qiantang Estuary and Its Influence Mechanism

根据2012年5月在钱塘江河口获取的潮流和悬沙浓度数据,采用机制分解法研究各输沙项的特征及贡献率,探究了钱塘江河口悬沙输运特征及影响机制。结果表明:钱塘江河口的欧拉余流和斯托克斯余流方向基本向海。小潮至大潮的平均含沙量与平均流速呈正线性关系,导致涨急、落急均出现再悬浮现象,悬浮泥沙由海转向陆地输运。钱塘江河口悬沙输运的贡献项以平流输移和潮泵输移为主,其平流项和潮泵项之和占潮周期单宽净输沙通量的87%以上;澉浦横断面在小潮汛期从左岸到右岸的平流项通量减小了1.71 kg·m^(-1)·s^(-1),潮泵效应项和垂向净环流项通量增大了1.34 kg·m^(-1)·s^(-1),且沉积物在尖山河段下游和杭州湾进行水沙交换。

The study analyzed the tidal dynamics,sediment suspension and sediment transport characteristics of the Qiantang estuary,which has significance for solving the problem of siltation and topographic evolution of the estuary.Based on the field observation data of tidal current and suspended sediment concentration(SSC)in May 2012,the characteristics of sediment transport are analyzed by using the mechanism decomposition method,and the characteristics and influence mechanism of suspended sediment transport in the Qiantang estuary are explored.The results show that the direction of the Euler residual current and Stokes residual current is seaward.The average sediment concentration had a significant linear correlation with average current speed during the neap and spring tide.which indicates strong re-suspension events during the flood and ebb tide,the asymmetry of the sediment transport lead to the suspended sediment from sea to land during the tidal cycle.The suspended sediment transport contribution is mainly advection transport term and tidal pump transport term in Qiantang estuary,the variation exceeds by 87%.Cross-section of Ganpu,when suspended sediment was transported from deep water area to shallow water area,it was found that the contribution of advection terms reduced by 1.71 kg·m^(-1)·s^(-1),however,the contribution of tidal pumping and shear diffusion terms increased by 1.34 kg·m^(-1)·s^(-1),and the sediment-water exchange between the Jianshan river and the Hangzhou bay.