长江口强盐水入侵后期盐度分布规律分析

Observation And Analysis of Saltwater Intrusion in the Changjiang Estuary

2014年2月长江河口发生强盐水入侵事件,本文利用该盐水入侵后期的观测资料分析了盐度的空间分布和时间变化。结果表明,严重盐水入侵事件后期南支中下段、整个北港、南港盐度均严重超过饮用水标准,且出现垂向分层现象,只有南支上段出现淡水。盐度沿横向断面的分布,除了南支中段断面因前期北港严重正面入侵导致盐水通过新桥通道上溯而表现为盐度值南高北低外,其它所有断面都在涨潮流科氏力右偏的作用下表现为北侧盐度大于南侧。在南槽横断面,强烈的盐水楔产生向陆的斜压压强梯度力,出现表层落潮、底层涨潮的现象。

The severe saltwater intrusion occurred in the Changjiang Estuary in February 2014. The author analyzed the spatial distribution and temporal variation of salinity in this paper., North Passage and South Passage in the case that the river discharge approaches monthly mean value. The result shows there existed severe salinity exceeds to the drinking water salinity standard and salinity stratification at the middle and lower reaches of the South Branch, the whole North and South Channel except at the upper reaches of the South Branch during the observation period because there was a severe saltwater intrusion event before the observation. The salinity was higher on the north side than on the south side along the transections due to the right avertence effect of Coriolis force on the flood current, except along the transection at the middle reaches of the South Branch,where the salinity on the south side was higher than on the north side due to the saltwater upstream intrusion through the Xinqiao waterway caused by the severe saltwater intrusion happened in the North Channel in early days. There appeared ebb current at surface layer and flood current at bottom layer along the transection in the South Passage due to the landward baroclinic pressure gradient force induced by the strong saltwater wedge.