长江口拦门沙河段航道回淤的水流动力环境*

对长江口拦门沙河段航道回淤的水流动力环境进行了研究，结果表明：1）长江口拦门沙河段的水流动力是引起北槽深水航道冲刷的基本动力，在长江口12.5 m深水航道贯通后，航槽内的水流冲刷能力沿程普遍增强；2）径流变化与北槽深水航道回淤无明显关系；3）在长江口拦门沙河段，水流是一种相对稳定的周期性变化动力，洪枯季无明显差别；4）天然情况下长江口拦门沙河段的河床时刻处于一种动态平衡中，决定这种平衡关系的是水流和波浪两种动力，当仅有水流动力作用时，长江口拦门沙河段的河床形态就不再处于平衡状态，主槽将往冲深方向发展。

Hydrodynamic condition in channel siltation at the mouth bars of the Yangtze estuary

This article researches the hydrodynamic condition in channel siltation at the mouth bars of the Yangtze estuary.From the research results,some perceptions are as follows:1)In the mouth bars,flow dynamic is the main power of erosion in the deep-water channel of north passage,and the erosion power generally enhances in the channel,after the 12.5 m channel at the Yangtze estuary being through.2)The correlation between the change of runoff and the siltation in the deepwater channel of north passage is not distinct.3)At the mouth bars of the Yangtze estuary,water flow is a kind of relatively stable power with periodic change;there is no obvious difference between flood season and dry season.4)Under the natural condition,the riverbed at the mouth bars of the Yangtze estuary is in a dynamic equilibrium which is resulted from the flow dynamic and wave dynamic.When it is only under the action of flow dynamic,the riverbed at the mouth bars of the Yangtze estuary is not in an equilibrium state any more,and the scouring depth tends to further develop in the main channel.