钱塘江河口七堡段氯度时空变化及与水文的关系

Temporal and spatial variation of chlorinity and its relationship with hydrology in Qibao Section of Qiantang Estuary

对10多年钱塘江河口七堡段大量的氯度、水文、地形等实测资料进行了统计、分析和比较,结果表明:在径流、潮流此消彼长的影响下,河口闸口—仓前河段咸淡水掺混最为强烈,径流大则氯度低,潮汐强则氯度高,但氯度垂向分布比较均匀,横向差异小,主槽氯度大于边滩;连续丰水年、连续枯水年,盐水入侵均较弱,径流从丰转枯的第一年,盐水入侵较强;大潮期受潮波变形和涌潮等影响,涨潮动力显著大于落潮,易发生盐水入侵;潮差是潮动力的重要指标,潮动力决定盐水入侵强度,潮差对河口的盐水入侵具有重要的指示作用。

Based on the statistics,analysis and comparison of the salinity,hydrology and terrain data in the Qibao Reach of Qiantang Estuary in more than 10 years,the results show that due to the influence of runoff and tidal currents,the most intensive mixing of salt-water and fresh water occurs in the reach from Zhakou to Cangqian.Strong runoff corresponds to lower chlorinity while higher chlorinity is accompanied by strong tides.The vertical and lateral distribution of chlorinity is relatively uniform,but the concentration in the main channel is greater than that in the marginal bank.Saltwater intrusion is weak in continuous wet years and continuous dry years,but it is strong in the first year of the runoff transition from abundant to dry.In spring tide,influenced by tidal wave deformation and tidal bores,flood tidal force is greater than ebb tidal force and saltwater intrusion is tend to occur.Tidal range is an important indicator of tidal power,which determines the strength of saltwater intrusion.Tidal range has indicative impacts on salt-water intrusion in estuaries.