长江河口南北槽输沙机制及浑浊带发育分析

MUD TRANSPORT CALCULATION IN YANGTSE ESTUARY AND ANALYSES OF FORMATION OF TURBIDITY MAXIMUM

本文运用机制分解的方法计算了长江口南北槽浑浊带区域内的余流和悬沙单宽输移量,并据此探讨了浑浊带的发育过程。

The methods developed by Fisher and Dyer have been adopted in the calculation of mud transport in the North and South Passages in the Yangtse estuary using observed data. Results show residual current (both in Eulerian and Lagrangian concept) has a regular longitudinal distribution under dry season discharge with a no residual current point in calculated reach, but under flood discharge a particular distribution with two extremities outward and the midway inward. Such distribution patterns are caused by water flows from the North Channel and produce vast tidal flat to the south. The principal mud transport factors are fluvial-input-induced ad-vection, tidal pumping and, to a lesser degree,vertical circulation and shear effect. And the trapping effect of the factors act as generating mechanism of the turbidity maximum in the estuary. On the upstream side of the center of turbidity maximum the net transport of sediment is toward sea and on the downstream side toward land. In this process the sediment transport induced by the vertical gravitational circulation only plays a minor role.