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2003年三峡水库蓄水运行以来,进入长江中下游的年平均径流量变化不大,但输沙量锐减。分汊河段的演变对水沙条件的变化十分敏感,本文对长江中下游鹅头型、弯曲型、顺直型分汊河段的演变与调整进行了系统分析,分流比及汊道冲淤情况实测资料表明,长江中下游各种分汊河段的演变调整具有较好的一致性,比降较大的汊道趋于发展,与汊道分流比的大小关系不大。对此,分析认为主要是因为来沙大幅度减少后,河道由淤积型转换为冲刷型,水流条件的作用凸显,比降较大的汊道易于多冲或是少淤,随之呈现出发展态势。
Since the Three Gorges Reservoir was put into operation in 2003, the annual average runoff entering the middle and lower reaches of the Yangtze River has not changed much, but the amount of sediment has dropped drastically. The evolution of the Fenghuai section is very sensitive to the change of water and sediment conditions. This paper systematically analyzes the evolution and adjustment of the goose head, curved and straight sections in the middle and lower reaches of the Yangtze River. The diversion ratio, The actual measured data show that the evolution and adjustment of various sub-reach sections of the middle and lower reaches of the Yangtze River have a good consistency. The larger than the larger ones tend to develop, which has little to do with the diversion ratio. In this regard, the analysis shows that the main reason for this is that after the arrival of sand was drastically reduced, the channel changed from siltation to scouring, and the effect of water flow conditions was prominent. situation.