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荆江三口是联系长江和洞庭湖的纽带,而近60年来三口分流分沙比呈不断减小的趋势,改变了干流的水沙过程,对荆江河段冲淤起着不可忽视的作用。利用实测水沙资料,探讨了分流分沙对干流河道冲淤的影响机理,定量分析了三口分流分沙变化对荆江河道冲淤的贡献值。结果表明:荆江三口分流分沙会使干流河道增淤,1957-2010年,三口分流分沙引起的年均增淤量为0.88亿t,且随分流比的减小呈减小趋势;增淤量的减小促进了荆江河段的冲刷,1957-2010年间,三口分流分沙变化对荆江河段的累计冲刷贡献量为0.95亿t,贡献率为5.23%,且三口分流分沙变化对荆江河段冲刷的促进作用沿时程呈减弱趋势。
The three Jingjiang rivers are the linkages between the Yangtze River and Dongting Lake. However, the diversion and sediment-to-sediment ratio of the three ports has been decreasing continuously in recent 60 years, changing the water and sediment process of the mainstream and playing an irreversible role in the scouring and silting of the Jingjiang reach. Using the measured water and sediment data, the influence mechanism of distributary sediment on the scouring and silting of the mainstream is discussed, and the contribution of the three changes of distributary sediment to the scouring and silting of Jingjiang River is quantitatively analyzed. The results show that the diversion and sedimentation of Jingjiang River will make the mainstream of the mainstream to be silted up. From 1957 to 2010, the annual average deposition due to the diversion and sedimentation of the three ports is 88 million tons, decreasing with the decrease of the diversion ratio. The decrease of the quantity promoted the erosion of Jingjiang reach. From 1957 to 2010, the cumulative contribution of the diversion and sediment change of the three branches to Jingjiang reach was 955 million t, accounting for 5.23% The promotion of river scouring tends to weaken along the time course.