长江口北槽洪季断面流速分布与泥沙输运特性

Distribution of flow velocity and characteristics of suspended transport in cross- sections of North passage of Yangtze River Estuary during flood seasons

为了解长江口北槽涉水工程对该区域水沙条件的影响,利用2009年8月北槽4个同步走航断面的水文泥沙资料,根据通量守恒原理,采用横向均匀、垂向时变的网格,经过时间插值、空间插值和投影的方法,将数据统一到计划断面,对北槽坡槽的水流结构分布特征及泥沙输运特性进行了分析。结果表明:北槽南、北边坡和深槽的涨落潮流速具有不同步的特征,南、北边坡先涨先落、深槽后涨后落,平流项输运和潮泵效应是北槽泥沙输运机制的主要影响项;北槽悬沙在深槽和南边坡向海输运,而在北边坡则是向岸输运,这种局部差异可能是北槽拐弯段北边坡淤积严重的重要原因之一。

To better understand the influence of project constructed in the North passage of Yangtze River Estuary on flow and sediment condition in the area, on the basis of the hydrological and sediment data collected in August, 2009 at 4 cross - sections in the North passage of the Yangtze River Estuary, and by the flux conservation principle and projection methods, the data is unified to the planned cross - section by the temporal and spatial interpolation on a horizontal - uniform - and - vertical - varying mesh. The distribution characteristics of flow structure and sediment transport features are analyzed. The result shows that the Ebb and flow tide of deep trough and side - slopes is asynchronous in that the south slope and north slope reache the high tide before deep trough and south slope and north slope reach low tide after deep trough; the advection transport and tidal pumping effect is the main sediment transport mechanism; for the deep trough and south slope, the suspended sediment transports toward the sea, while the suspended sediment on the north slope transports toward the shore - bank, which is one of the important reasons for the serious deposition on north slope.