基于分层系数法与混合比法的长江口盐淡水混合规律研究

采用长江口4条入海汊道3个月的水文测验资料,研究长江口的盐度分布格局和盐淡水混合情况,运用分层系数法和混合比法对长江口实测盐度数据进行分析。结果表明:北支汊道的盐度最高,洪、枯变幅大,全年均为垂向均匀混合型;南支3条汊道盐度从高到低依次为南槽、北槽、北港;盐淡水混合强度从高到低依次为南槽、北槽、北港,这与长江口北港分流量大于北槽、北槽分流量大于南槽的格局相对应;枯季的混合强度大于洪季,大潮的混合强度大于小潮。盐淡水的混合强度呈周期性变化,涨急前后垂向混合程度最大,涨潮的混合强度高于落潮时的混合强度。

The fresh and salt water mixing analysis of Yangtze River estuary based on lamination factor and mixing ratio method

The paper analyses the salinity distribution and salt-fresh water mixing of Yangtze River estuary by the recent three months hydrology data .The lamination factor and the mixing ratio concept are applied to analyse the mixed type.The result shows that:The salinity of the North Branch is the highest of the four sub-channels and changes greatly between floods and droughts .The North Branch is a typical well-mixed estuary the whole year.The salinity of the three south branches ranks from high to low as follows:the South Passage,the North Passage and the North Channel.The fresh and salt water mixing intensity ranks from high to low as follows:the South Passage,the North Passage and the North Channel,which is adapted to the situation:the water discharge of the North Channel is the highest,secondly the North Passage,the South Passage is the lowest.The mixing intensity of dry season is higher than flood season,while the mixing intensity of spring tide is higher than neap tide.The mixing intensity display cyclic variations over time,which is the highest around the maximum flood and the intensity of flood tide is higher than ebb tide.