钱塘江河口潮波特性变化及原因剖析

为掌握钱塘江河口潮波特性的响应机制，采用小波分析法研究了该河口 6 个潮位长期观测站的年平均高、低潮位及年平均涨潮历时等时间序列的变化特征，结合该河口实施的治江缩窄工程及径流周期性变化，探讨了该河口潮波特性时空变 化的因果关系。结果表明：1953—2017 年，钱塘江河口呈现出高潮位显著抬升、涨潮历时缩短，低潮位在河口上段略有抬高、中段大幅抬升、下段变化不大的趋势；受治江缩窄工程进展、位置以及径流周期性变化等影响，各站潮波特性的变化在时间上存在差异；钱塘江河口的治江缩窄工程加剧了河口下段的潮波变形和潮波反射，增强了河口上、中段的河流特性，导致高潮位抬升、涨潮历时缩短，是造成潮波特性变化的主要原因；径流直接影响河口上、中段的潮位和潮流，此外，还通过流速变化改变河床地形而间接影响潮波特性。

Variation trends of tidal characteristics in the Qiantang River Estuary and cause analysis

In order to grasp the response mechanism of the tidal characteristics in the Qiantang River Estuary, the temporal and spatial changes of tidal characteristics in the estuary and its reason were studied. The wavelet analysis method was used to study the changes of the annual mean high tide level, low tide level and flood -tide duration at the Zhakou, Qibao, Cangqian, Yanguan, Ganpu and Zhapu stations along the Qiantang River estuary. And combined with the implementation progress of the estuary narrowing project and the periodic variation of runoff, the causal relationship of the tidal wave characteristics was discussed. In the past 65 years, the high tide level in the Qiantang River Estuary has shown significant lift, while the flood-tide duration has been shortened. The low tide level has raised slightly in the upper reaches, raised greatly in the middle reaches and little changed in the lower reaches of the estuary. However, due to the progress of the estuary narrowing project and the periodic variation of runoff, the variation of tidal characteristics at each station is different in time. The estuary narrowing project in the Qiantang River Estuary intensifies the deformation and reflection of tidal waves in the lower reaches of the estuary, enhances the river characteristics in the upper and middle reaches, causes the rise of high tide level and shortens the flood-tide duration. These are the main reasons for the variation of tidal characteristics. Runoff directly affects the tidal characteristics in the upper and middle reaches. In addition, it also indirectly affects the characteristics by changing the riverbed topography through the change of velocity