长江中游典型顺直河段交错边滩复归性演变机理

Periodic Evolution Mechanism of Staggered Beach in Typical Straight Reach of the Middle Yangtze River

顺直河段交错边滩受水动力条件、来水来沙情况、边界条件、滩槽分布及其相互作用的影响,使得其演变趋势较为复杂.本文以长江中游典型顺直河段——界牌河段为例,在阐述了河段形态特征和河道水文泥沙特征的基础上,分析了顺直河段交错边滩的演变特点及机理.在此基础上,结合该河段交错边滩复归性演变规律,分析了三峡工程蓄水前后来水来沙变化,人类河段治理工程等对交错边滩复归性演变周期的影响,研究了交错边滩的演变趋势.结果表明,界牌河段交错边滩的复归性演变规律仍将延续,但演变周期将延长.

Staggered beach evolution process wss effected by hydrodynamic condition, sediment discharge, boundary condition, beach and channel distribution. These factors had made the regime evolution of the straight reach complicated. In a case study of Jiepai Reach, we analyzed the evolution mechanism of straight reach channels. Based on river morphology and sediment transport characteristics, the staggered beach evolution characteristics had been analyzed. The evolution mechanism including hydrodynamics mechanism, sediment transport mechanism, boundary condition had been researched. Many factors that effected the staggered beach evolution had been studied, including the runoff and sediment change before and after the impoundment the three gorges reservoir, the river regulation project. The results showed that the periodic evolution of staggered beach and the straight section shape in ]iepai Reach will continue in the future, nevertheless the periodic time will become longer. It indicated that we should take more consider of time point as well as space point in our future project plans.