长江中下游鹅头型汊道演变规律的分析

鹅头型分汊是长江中下游城陵机至江阴分汊河段中形最复杂、放宽率最大，分汊数量多，占汊道总长度最大（达40％）的一种分汊形式。其演变主要于本身的河床形态，边界条件及水流条件的变化，基本上遵循新生汊道－产生、扩大、平移、衰亡而完成它一个完整的演变周期。由于汊道的弯曲引起滩地的大面积坍失，主流线大幅度摆动，各汊道水沙的重新分配及纵横剖面的调整，是一种最不稳定的分汊型式，对鹅头型分汊河道的形成条件及演变特征的研究是制订相应的规划整治措施，稳定河势，使其朝着有利的方向发展的前提条件，也是实际工程迫切要求解决的问题。

Study on the Evolution of Goose-neck Bifurcated Channel in the Middle and Lower Reaches of Changjiang(Yangtze) River

The goose|neck bifurcated channel is the one with the most complicated shape, the biggest broaden|rate and the largest in number in the middle and lower reaches of the Changjiang(Yangtze) river, and its length is almost 40 percent of that of the whole bifurcated channel. The evolution of this kind of channel mainly depends on the morphology of river bed, the boundary conditions and inflow conditions. In this paper the morphology characteristics and the evolution process of the goose|neck bifurcated channel are analyzed based on the data obtained by observation from Chenglingji to Jiangyin in the middle and lower reaches of the Changjiang river. Furthermore, the cause for the formation of goose|neck bifurcated channel is also investigated. The results of this paper are helpful to the river regulation in engineering practice.