三峡工程运行后长江中游窑监滩群航道整治线宽度变化

Channel Regulation Width Changes of the Yaojian Shoal Group in the Middle Yangtze River After Impoundment of the Three Gorges Project

三峡水库蓄水运行后,长江中游来水来沙和航道条件发生了很大变化,黄金航道整治面临新的挑战,从天然冲积河流导出的整治线宽度公式已不适用于坝下游河道。本文以下荆江著名的窑监滩群为例,基于唐存本的"河床断面法",根据三峡工程运行后枯水实测地形资料绘制该河段整治水位下的t-B关系曲线(最小航深-河宽关系曲线),分析了三峡工程运行后航道整治线宽度变化。研究表明,受清水冲刷影响,窑监滩群航道整治线宽度呈逐渐放宽态势,但调整幅度逐年减小,2003~2014年整治线宽度可为800~1 100m。根据2014年枯水地形资料,绘制了满足航深分别为4.5m和6.0m时整治水位-整治线宽度的关系曲线,探讨了整治水位与整治线宽度的组合关系并建立了拟合公式。研究结果可为类似滩群航道整治工程设计与维护提供依据.

Since operation of the Three Gorges Project(TGP),runoff and waterway conditions have been changed greatly in the middle Yangtze River,which brings new challenges to the golden waterway regulation.As many methods to determine channel regulation width are based on the flow-sediment process in natural alluvial river,it is not applicable to use these methods in downstream reaches of the TGP.Taking Yaojian shoal group in the Lower Jingjiang River as an example,changes of channel regulation width and its combination with regulated water stage after operation of the TGP were analyzed based on the principle of ‘river bed section analysis’.Firstly,the t-B curves(the relation curve of minimum navigation depth versus corresponding river width) based on the bathymetry after the TGP in dry season were plotted.Secondly,channel regulation width was determined with inner envelop line of t-B scatters and its annual change was analyzed.Results show that,channel regulation width broadens gradually with the TGP-induced channel bed erosion,but the adjustment decreases annually.Channel regulation width ranges from 800 to 1100 m during 2003~2014.Besides,relation curves of regulated water stage Z versus channel regulation width B_t for designed navigation depth equal to 4.5 m and 6.0 m respectively were plotted,using the bathymetry in dry season of 2014.The relationship of regulated water stage and channel regulation width was discussed and fitting equations are given.This study is expected to provide a method for navigation channel regulation design and maintenance management in similar reaches.