钱塘江涌潮流速研究

Study on velocity of tidal bore in Qiantang Estuary

涌潮流速是涌潮的重要特征,一直深受涌潮研究者的关注。21世纪以来,随着声学剖面流速仪的使用,涌潮流速观测有了突破性的进展。本文收集了2003年以来9次钱塘江涌潮流速观测资料,结合理论分析和数值模型计算成果,分析了影响涌潮流速的因素、涌潮流速时空分布规律。结果表明:影响涌潮流速的微观因素主要有涌潮高度和陡度、潮前流速和潮前水深、风速风向等;在涌潮河段,最大流速即为最大涌潮流速,与当地潮差呈良好的正相关关系;在弯道段,涌潮流速在弯道凸岸大于凹岸;涌潮到达后流速从落潮迅速转化为涨潮,没有明显的憇流现象,且涨潮流速过程存在多峰现象;涌潮垂向流速基本上比纵向流速小1个量级,在涌潮时段垂向流速相对较大。

The tidal bore velocity is one of the important indexes of the tidal bore,to which much attention has been paid. Since the21 st century,the observations on tidal bore velocity have a breakthrough by use of Acoustic Doppler Current Profilers（ ADCP）. In this paper,based on the data of tidal bore velocity collected from 9 times field work since 2003,the theoretical analysis and the computational results of numerical models,the influence factors and space-time distribution of tidal bore velocity are analyzed. The results show that the major micro influence factors of the tidal bore velocity are the height and steepness of tidal bore,the ebb velocity and depth ahead of the tidal bore,wind speed and direction,etc. In the tidal bore section of the river,the maximum flow velocity is the maximum tidal bore velocity,and a good positive correlation to the local tidal range. In the bend section of the river,tidal bore velocity near the convex bank is greater than that near the concave bank. After tidal bore arrival,velocity of ebb tide rapidly becomes that of flood tide with no obvious slack water phenomenon,and there is a multimodal phenomenon in the flood velocity process. The vertical flow velocity is larger in the tidal bore period,which is around one order of magnitude smaller than its longitudinal velocity.