钱塘江涌潮观测及其动力学特性研究

Observation and dynamic characteristics of tidal bore in Qiantang River,China

为了研究钱塘江涌潮的动力特征,于2013年11月5—6日在钱塘江杭州段采用沿海声层析(Coastal acoustic tomography,CAT)和温盐深仪(Conductivity temperature depth,CTD)进行了涌潮观测试验。两个观测站位分别设置在沿江两岸,站间距为3050 m,试验历时26 h,成功观测到两次涌潮的全过程。结果表明:两次涌潮到来前后,由双向传播时间差计算得到的断面平均流速的变化范围分别为0.39^-1.08、0.31^-0.85 m/s(东向流为正),水位升高的最大幅度分别为1.38、1.14 m;两次涌潮通过观测站位的波速分别为-8.69、-8.43 m/s;观测断面流量的变化范围为-7753.00~3504.49 m3/s,整个试验期间的平均流量为644.14 m3/s;涌潮的弗劳德数介于1.19~1.29之间,表明观测涌潮为波状涌潮;涌潮到达前后能量的损耗率小于0.6%,符合波状涌潮的能量守恒关系。

A 26-hour observation of tidal bores was carried out by a coastal acoustic tomography（ CAT） system and conductivity temperature depth （ CTD ） in two stations at both sides with a distance of 3050 m diagonally across Qiantang River from 5 to 6 November, 2013 to valuate the dynamic characteristics of tidal bore in Qiantang River, China. The range-averaged current velocities calculated from the reciprocal sound transmission data were changed from 0 . 39 m/s to -1 . 08 m/s before arrival of tidal bore with the maximal water level changes of 1 . 38 m and from 0 . 31 m/s to -0 . 85 m/s after arrival of tidal bore with the maximal water level changes of 1 . 14 m （ the positive ve-locity towards the east）. The mean phase speeds of two tidal bores were estimated to be -8. 69 m/s and -8. 43 m/s at the two stations, respectively. During the whole experiment, the volume transport was varied from-7753. 00 m3/s to 3504. 49 m3/s through the section, with a mean of 644. 14 m3/s. The Froude numbers of tidal bores were estimated to be from 1. 19 to 1. 29, indicating that the observed tidal bores were undular bore, with tidal bore energy losses of less than 0. 6%, conforming to energy conservation relations for undular bores.