三维理想河口盐水入侵对径潮驱动变化的响应

为探究在人类活动与气候条件改变的影响下,径潮动力以及水深的改变对河口区域盐水入侵的影响,建立了三维理想河口盐水入侵数值模型,分析了纵向环流及盐度的垂向与横向沿程分布,研究了垂向与横向剪切作用以及潮泵效应引起的纵向盐输运对盐水入侵的影响以及盐分输运过程对径潮动力与水深变化的响应。结果表明:盐水上溯程度对流量与潮振幅的变化有明显响应,流量增大与潮振幅增大对盐水入侵均有抑制作用；在较浅的河口,潮驱动增大在河口上下游引起相反的潮平均盐度变化趋势,这与横向、纵向剪切与潮泵效应分别引起的纵向盐输运对径潮水深条件的响应相关。

Response of three-dimensional ideal estuarine salt intrusion to changes in river and tidal forcing

In order to explore the response of estuarine salt intrusion to river and tidal forcing as well as water depth under the influence of human activities and climatic changes, a three-dimensional numerical salinity model for three-dimensional ideal estuaries was established. By analyzing the vertical and lateral distributions of longitudinal circulation and salinity, the effects of vertical salt transport induced by the vertical and lateral shear as well as the tidal pumping on saline intrusion, and the response of salt transport to radial tidal dynamics and water depth were studied. The results show that the salt intrusion is sensitive to changes in the river runoff and tidal forcing. In a relatively deep estuary, increasing the runoff or tidal forcing can reduce salt intrusion throughout the estuary. In shallower estuaries, the increase of tidal drive causes the opposite trend of tidal-averaged salinity change in the upstream and downstream of the estuary, which can be explained by the response of longitudinal salt transport to radial tide depth conditions caused by transverse shear, longitudinal shear and tidal pump respectively.