三峡水库运用以来大马洲水道演变特性及对航道条件的影响

大马洲水道为荆江典型的单一顺直微弯河段,三峡水库蓄水以来该河段局部区域发生一定调整,航道条件也有向不利方向转化的趋势。根据三峡水库蓄水前后的水文及地形资料分析表明,该河段近期内将不会发生大的河势变化,主要表现为局部区域滩槽格局的调整;汛末退水加快,枯期流量有所增加,对滩槽的稳定性构成影响;未来一段时期河道滩槽变化将继续呈现滩冲槽淤的规律,河道沿程将发生不同程度的展宽,河床将向较宽平的"U"河道发展,过渡段主流摆动幅度和频率都将增大;航道条件虽然从长期来看有逐渐向好的趋势,但期间局部航道条件也将不稳定甚至恶化。

Evolution Features and Its Influence on Navigation Conditions of Damazhou Waterway after Operation of Three Gorges Project

The Damazhou Waterway is a typical straight and slightly curved river reach of the Jiangjiang River.After the operation of the Three Gorges Project（TGP）,the river reach has certain local changes,and the navigation conditions has been affected unfavorably.Analysis of the hydrological and topographic data before and after the operation of the TGP shows that,the river regime of this river reach will not change significantly in the near future,yet situations of the channel and bars have some local adjustment.Falling of water is speeded up at the end of the flood season,and flow rate is increased during dry season.The stability of the channel and bars is therefore affected.In a certain long period in the future the evolution of the river will continue to be scouring of the bars and silting of the channel.The width of the channel will be increased to different degrees along the river.Cross section of the river will develop towards the ＂U＂ shape which is relatively wide and flat.The amplitude and frequency of fluctuation of the main current at the transition section will increase.Though in the long run the navigation conditions have a tendency to getting better,local navigation conditions may get unstable and even worse.