为更好研究长江口Sa分潮的特性,建立了大通至长江口感潮河段的二维水动力数学模型,通过模拟径流与潮汐共同作用下的水动力过程,并设置上下游不同条件的对照组,分析了河口段Sa分潮的影响因子及响应规律.结果表明,长江河口段Sa分潮由上游径流变化和外海Sa潮波共同作用产生,径流对上游站点影响占优、外海潮波对下游影响占优.径流使得河道内分潮振幅产生了沿程衰减的趋势,这是河口的Sa分潮特征不同于外海的原因,也说明径流是其主要的影响因子;而外海的Sa潮波只给予了其一个沿程定值.Sa分潮振幅只受径流的年内变化大小和外海Sa潮波振幅大小影响,不受平均径流量和平均海面的影响.径流量的变化会导致沿程Sa分潮振幅发生响应变化,且上游比下游站点响应更敏感;外海Sa潮波振幅的变化会使沿程振幅发生大致等量的变幅.三峡建成后河口段Sa分潮振幅有所减小,年际变化减小.%In order to study the characteristics of Sa partial tide in Yangtze estuary, a two-dimensional hydrody-namic model for the tidal reach of the Datong-Yangtze River estuary was established. By simulating the hydrodynam-ics in response to runoff and tides and setting different upstream and downstream boundaries, the influence factors and responses of Sa at Yangtze River estuary reach were analyzed. The results show that the Sa partial tide at Yang-tze estuary is co-produced by runoff and tidal action. The influence on upstream sites comes mainly from runoff, and the influence on downstream is mainly from the offshore tide. The change during a year of runoff produces the decay trend along the way to the amplitude of Sa along the estuary reach;meanwhile, the offshore Sa partial tide gives a constant value to it, it′s the reason why the characteristic of the Sa along the estuary reach is different from in off-shore area, and it proves that the runoff is the main influence factor. The amplitude of Sa in estuary is only affected by the runoff and offshore Sa, but not by the average level in offshore and the average discharge of runoff. The change of the runoff′s variation during a year will affect the amplitude of Sa, and the upstream sites are more sensi-tive than downstream;the change of offshore Sa will produce a similar amount of change to it. After the completion of the Three Gorges project, the interannual variability and the average value of Sa′s amplitude reduced slightly.
展开▼
