珠江河口岸线变化对潮动力的影响

为研究珠江河口岸线变化对潮波特征的影响,基于D-Flow FM(Delft 3D-flow flexible mesh)建立珠江河口二维水动力数值模型,模拟的水位、流速流向结果与观测数据吻合良好。利用T_TIDE对模型结果进行调和分析,通过振幅比、相位差和潮能通量探讨岸线变化对潮汐动力特征的影响。结果表明:珠江河口半日分潮M_2的振幅和1/4日分潮M_4的振幅总体均呈增大的趋势,潮能通量呈减小的趋势。珠江河口整体表现为潮汐不对称加剧,涨潮占优增强。岸线变化通过影响径流作用、河口形态、浅水效应和潮能辐聚作用,影响珠江河口的分潮振幅、相位、潮汐不对称和潮能通量等潮汐特征。由岸线变化带来的潮汐振幅增加、潮汐不对称性加剧和涨潮占优趋势加强,可能会导致风暴潮等沿海灾害和严重的淤积问题。

The Influence of Coastline Changes on Tidal Dynamics in the Pearl River Estuary

In order to study the influence of shoreline variation on tidal wave characteristics in the Pearl River Estuary, a two-dimensional hydrodynamic model for the Pearl River Estuary was established based on D-Flow FM. The modeled results matched well with the observation. The harmonic analysis of the model results is carried out by T_TIDE. The influence of shoreline variation on tidal dynamic characteristics is discussed by amplitude ratio, phase difference and tidal energy flux. The results show that the semidiurnal constituent M2 amplitude and the 1/4 diurnal constituent M4 amplitude generally show an increasing trend. The tidal energy flux shows a decreasing trend. The whole Pearl River Estuary is characterized by the increase of tidal asymmetry and the flood dominance. By affecting runoff action, estuary morphology, shoaling effect and tidal energy convergence, the tidal characteristics of the Pearl River Estuary, such as tidal amplitude, phase, tidal asymmetry and tidal energy flux are affected by the change of shoreline. The increase of tidal amplitude, tidal asymmetry and the flood dominance caused by shoreline changes may enhance the coastal disasters such as storm surge and severe siltation problem. Therefore, careful consideration must be given to any proposed artificial changes to coastline.