长江中下游鹅头型汊道航道整治目标河型研究

Objective river pattern of waterway regulation of goose-head-shaped anabranching channel in the Middle and Lower Yangtze River

鹅头分汊河型由于其汊道大幅平移及主支汊频繁交替,历来是碍航问题最为突出的河段,目前关于鹅头分汊河型的治理目标存在微弯分汊和微弯单一河型的争议。本文在总结鹅头分汊河型碍航特性的基础上,结合其滩槽格局成因,从分汊河道水流能量守恒原理出发,提出了鹅头分汊河道航道整治的目标河型:认为进口节点的挑流作用放大了水流的年内横向摆幅,使得边滩难以长期稳定;进出口节点的存在限制了汊道的延伸平移,因此保留分汊河型是适应这一特征的必然选择。同时保持两汊较大的阻力差异,削弱主支汊格局对进口水流条件的敏感性,将更有利于主航槽的稳定,即存在一定曲率差的分汊河型是鹅头型汊道航道整治的目标河型;具体河段的汊道曲率可根据进口水力特征及进出口河床高程差计算而得。

Problems on navigation of the goose-head-shaped anabranching channel （GHA for short） is extremely serious because of branches substantially shifting and altering. Controversy about objective river pattern of the GHA regulation lies in anabranching or single meandering channel. Characteristics of navigation-obstructing in GHA are summarized in this paper, and objective river pattern of waterway regulation is proposed based on cause of the riffle-pool sequence and energy conservation of waterflow in the anabranch- ing channel. The conclusions are as follows： （1） Inlet node of the GHA amplifies range of waterflow hori- zontal shifting and astricts translating and extending of the branches, so retaining anabranching pattern is in- evitable considering waterway regulation; （2） Maintaining significant resistance difference of the branches of GHA will meet the requirements of stability of navigation channel. On the whole, anabranching channel with a greater curvature difference calculated from inlet velocity and riverbed elevation is objective river pattern of GHA.