基于2015年洪季水文观测资料，分析了长江口洪季北槽大小潮期间落潮分流和分沙特征，及其差异和原因.观测结果显示：北槽大潮和小潮落潮分流比均值分别为41.9%和43.1%，大潮和小潮落潮分沙比均值分别为35.1%和39.0%，大小潮差异较小，故大潮落潮分沙情况可近似代表当月落潮分沙情况.大小潮期间北槽落潮分沙比与南北槽断面平均流速之比、断面平均含沙量之比和断面面积之比有关，而观测结果显示大小潮周期内南北槽断面面积比值、断面含沙量比值、断面流速比值均无较大差异.因此，大小潮北槽落潮分流和分沙情况差异不大.

This study investigates the characteristics of the ebb water and sediment diversion ratios during wet season in the North Passage, Changjiang Estuary and the reasons for the differences within neap-spring tidal cycles based on field measurements. The results of the measurements indicate that the averaged ebb flow diversion ratios of the North Passage in spring and neap tide are 41.9% and 43.1%, respectively, while the averaged ebb sediment diversion ratios of the North Passage in spring and neap tide are 35.1% and 39%,the averaged ebb sediment diversion ratios of the North Passage in spring can approximate representatively ebb sediment diversion status. The ebb sediment diversion ratio of the North Passage is dependent on the ratios of mean flow velocity, suspended sediment concentration and section areas of the North and South Passage. And these parameters show minor changes within neap-spring tidal cycles. Therefore, it can be concluded that the differences of ebb flow and sediment diversions of the North Passage within neap-spring tidal cycles are limited.