径潮流变化对长江潮流界位置的影响研究

A study of river-ocean's impacts on tidal current limit in the Changjiang River

赤潮流界是表征河口径潮相互作用的关键界面,受各种动力作用在空间上不断上下迁移。本文基于2012—2019年间长江口岸直水道五峰山至南支河段大范围实测资料,分析了46种径潮流组合下,长江主汊河段主深槽潮流界位置的变化。研究结果表明:(1)在径流条件一定时,随着潮差的减小潮流界位置逐渐向下游移动,初始时期潮流界位置下移速度较慢,后期加快。(2)在潮差一定时,当上边界径流量以同样速度增加时,枯水期潮流界向下游移动的速度快,平水期与丰水期潮流界向下游移动的速度会逐渐减慢。(3)潮流界距大通的距离与潮径比呈显著相关的对数关系,可用于今后潮流界位置的定量计算。潮流界位置随着潮径比的减小而下移,当潮径比约为0.56时,潮流界位置在江阴附近。新水沙条件下,长江潮流界位置的研究对“长江大保护”战略下河口海岸地区的开发规划具有重要现实意义。

Tidal current limit(TCL)is a key interface between river and ocean,and it migrates under different kinds of driving forces.This study focuses on the variation of the TCL in the main channel of the Changjiang River,based on 46 combinations of river and tide conditions measured from Wufengshan to the South Branch in the estuary.The results show that when river-ine water discharge remains at a certain level,the TCL migrates downstream with the decrease of tidal range.The downstream migration rate of the TCL speeds up from the beginning to the end.When the tidal range at a certain level and the riverine wa-ter discharge increases at the same rate,the rate of the TCL migrating downstream decreases from dry season to normal sea-son,and then to flood season.The distance between the Datong Station and the TCL is highly correlated with the ratio of tide to river in a logarithmic relationship,which can be applied for future quantitative calculations.The TCL migrates downstream as the ratio of tide to river decreases,and it locates around Jiangyin when the ratio is about 0.56.Under new situations,the study of the TCL has great practical significance for the planning in coastal and estuarine regions under the strategy of pro-tecting the Changjiang River.