磨刀门口门区三维水流盐度特性研究

Research on Three-dimensional Flow and Salinity Characteristic in Modaomen Estuary

采用2006—2008实测的水下地形数据,建立覆盖珠江八大口门至外海-30 m等深线附近的精细三维水流盐度数学模型,通过对各个分层的流场、盐度场平面分布及纵断面分布图进行分析,重点研究了磨刀门海域咸潮上溯规律。结果表明:磨刀门口门区落潮时流向向西发散,落潮流流速大于涨潮流流速,-12 m等深线处呈顺时针旋转流;枯季大潮期,底层盐度值比表层的盐度值大40%,咸淡水分层参数较大,底部存在高浓度盐水上溯现象,涨憩时刻盐度线密集处垂直变化梯度大于1/m,盐淡水混合较为充分,等盐线呈垂直分布,上溯距离达到最大值。

Using the newest measured underwater topography data of 2006—2008,this paper established a three- dimensional flow and salinity mathematical model from eight Pearl river estuaries to- 30 m isobath in the open sea. The Modaomen principle regulation of tide intrusion is studied through analyzing the alternation characteristic of flow speed and salinity on the ground of the respective layers,and horizontal and transversal salinity distribution. The results show that the calculation results are consistent with the observed data,revealing the distribution characteristic of the hydrodynamic power and salinity. Modaomen ebb flow diffuses to the west, and the ebb current velocity is greater than the flood flow. The flow rotates clockwise in- 12 meters depth contour; the underlying salinity is 40%larger than the surface values; during the dryseason spring tide period,the brackish- water stratification coefficient is bigger. There is tide intrusion phenomenon at the bottom of the brine, and the vertical salinity gradient of the change line density is greater than 1 / m in the rest up moment. Salt water mixing is more sufficient. As the salt line in vertical distribution, the affect t distance is the biggest.