考虑流量变化影响的西江感潮河道潮汐特征分析

本文基于2015−2017年西江感潮河道的潮位数据，应用非平稳潮调和分析模型NS-TIDE，研究了不同周期分潮振幅和迟角的时空变化特征、潮汐动力构成变化和潮波变形特征，并讨论了感潮河道中的潮位变形、极低潮位颠倒等现象的形成原因。结果表明，不同于全日、半日分潮振幅的沿程衰减和迟角的沿程递增，浅水分潮振幅先增后减，MS_f分潮振幅呈递增趋势、迟角有显著的增减交替变化；各个分潮的振幅洪季衰减速率大于枯季，迟角在洪季变化较大，表明径流顶托作用下的潮波向上游传播速度较慢。受径流、地形等因素的影响，在洪季和上游河段，MS_f分潮振幅更大，潮汐动力由主分潮向次分潮转移，M₄和M₂分潮振幅比的变化表明潮汐变形显著，MS_f与M₂、S₂分潮的振幅比较大时有最低低水位的颠倒现象。

Analysis of the tidal characteristics along the tidal reach of Xijiang River considering river discharge variation

Based on the tide level data along the tidal reach of Xijiang River from 2015 to 2017, we applied the nonstationary tidal harmonic analysis model NS-TIDE to study the spatial and temporal variation characteristics of the amplitude and phase of different cycles of tidal constituent, the change of tidal dynamics composition and tidal wave deformation characteristics, and discussed the causes of tidal level deformation and the reversal of the lowest low waters along the tidal reach. The results show that, unlike the diurnal constituent and semi-diurnal constituent along the tidal reach that have amplitude decay and phase increment, the shallow water component amplitude increases and then decreases, the amplitude of MSf is increasing, and the phase is changing alternately; the decay rate of each tidal amplitude is higher in the flood season than in the dry season, and the phase changes more in the flood season, indicating that the tidal wave propagates upstream more slowly under the top support of river discharge. Due to the influence of river discharge and topography, the amplitude of MSf is larger in the flood season and upstream section of the river, and the tidal dynamic composition changes from the main tidal constituent to the secondary tidal constituent; the change of amplitude ratio of M4 and M2 indicates significant tidal deformation, and the reversal of the lowest low waters when the amplitude ratio of MSf to M2 and S2 is relatively large.