三峡水库调洪调度对江湖汇流区洪水相互顶托的影响

Effect of the Three Gorges Reservoir operation on flood inter-jacking in the confluence section of rivers and lakes

三峡工程是长江干流重要的控制性工程,自水库蓄水以来,下游河段的水情发生了较大变化。基于1990-2017年长江与洞庭湖汇流区的监利、城陵矶、螺山3个水文站7-8月水位及流量资料,运用相关分析、对比分析、汇流比等方法系统研究三峡水库调洪调度运行期(7-8月)对江湖汇流区水情的影响。结果表明:监利站下泄流量占来水总量的比重由58. 81%增加到60. 53%,洞庭湖湖口城陵矶站出流的比重由43. 19%减少至37. 68%。监利与城陵矶的汇流比由1. 36增加到1. 61;监利、城陵矶、螺山3站的流量、水位均有所下降,其中减少或下降幅度最大的是螺山站,7-8月平均流量减少6401. 39 m^3/s,水位下降了1. 32 m;监利、城陵矶、螺山3站之间的水文相关程度有所下降,其中螺山站的流量与监利站的水位相关性较强,其相关系数为0. 9219;在不同量级流量水位下,江湖洪水相互顶托强度均有不同程度的减弱,但其顶托作用仍然存在,其中以螺山站高洪水位对城陵矶和监利站泄洪的顶托作用较强。

As the major control engineering on the main stream of the Yangtze River,the impoundment of the Three Gorges Project has resulted in significant hydrological changes of the downstream.Based on the data of water level and flow in July and August collected from three hydrometric stations on the Yangtze River and the Dongting Lake(Jianli,Chenglingji,and Luoshan Stations)during 1990 and 2017,this paper employs methods of correlation analysis,contrastive analysis and discharge ratio to study the effect of operation of the Three Gorges Reservoir in July and August on the hydrology of confluence section of the downstream rivers and lakes.The results showed that:the percentage of outflow discharge account for the total inflow discharge at Jianli Station increased from 58.81%to 60.53%,whereas that of the Chenglingji Station decreased from 43.19%to 37.68%.The discharge ratio of Jianli and Chenglingji Stations raised from 1.36 to 1.61.The water level at all of the three stations decreased,especially at the Luoshan Station where the mean water flow and water level in July and August decreased by 6401.39 m^3/s and1.32 m,respectively.The hydrological correlation between the three stations decreased;however,a relatively stronger correlation(correlation coefficient is 0.9219)exists between the water flow in Luoshan Station and the water level in Jianli Station.The inter-jacking influence,though decreased at all rivers and lakeswith different magnitude of water level/flow,still exist,especially prominent in the effect of the high-water level at Luoshan Station on the outflow discharge at Chenglingji and Jianli Stations.