三峡水库运用对水库下游水文分期的影响研究

Research on the Influence of Three Gorges Reservoir Operation on the Hydrological Staging of the Lower Reaches of the Reservoir

长江三峡等水库的建设运行,改变了下游径流过程及径流量的年内分配,也改变了长江中下游水文分期规律。为了分析三峡水库运用对长江中下游汛期和枯期分期的影响,本文采用基于长江中下游7个水文站的月径流重构序列进行变异分析和模糊统计两种水文分期方法,统计各站的汛枯期起止时间变化规律,结果表明:1961-1980年阶段长江中下游流域汛期为5-10月;1981-2002年阶段,宜昌至城陵矶河段汛期起止时间为6-10月,城陵矶至大通河段为5-10月;2003-2016年阶段,变异分析方法认为三峡蓄水后长江中下游流域汛期为5-9月,模糊统计法结果表明该时段汛期与天然径流规律一致为5-10月;若排除三峡水库蓄水的影响,则两种方法结果与1981-2002年阶段水文分期规律相同;进一步分析发现长江中下游5、10月径流量受三峡水库调度影响较大,且上游河段受影响程度明显大于下游,三峡水库的运用是水库下游汛枯期起止时间变化的主要原因。

The construction and operation of the Three Gorges Dam and other reservoirs in the Yangtze River have changed downstream runoff process and annual distribution,and also changed the hydrological staging law of the middle and lower reaches of the Yangtze River.In order to analyze the influence of the Three Gorges Reservoir operation on the flood seasons and dry seasons staging of the middle and lower reaches of the Yangtze River,two hydrological staging methods based on the monthly runoff reconstruction sequence of seven hydrological stations in the middle and lower reaches of the Yangtze River are used to calculate the beginning and ending time of the flood and dry seasons of each station.Results show that flood seasons in the middle and lower reaches of the Yangtze River from 1961 to 1980 ranged from May to October;during 1981 to 2002,the flood seasons from Yichang to Chenglingji was from June to October,while it is May to October from Chenglingji to Datong;during 2003 to 2016,the variation analysis method shows that flood seasons in the middle and lower reaches of the Yangtze River after impoundment of Three Gorges Dam is from May to September,but fuzzy statistical method shows that flood seasons during this period is consistent with the natural runoff law from May to October.If the impact of the Three Gorges Reservoir's water storage are removed,results of this two methods are the same as hydrological staging from 1981 to 2002.Further analysis reveals that in the middle and lower reaches of the Yangtze River,runoff during May and October is most greatly affected by Three Gorges Dam’s operation,and the upper reaches are more significantly affected than lower reaches.The operation of the Three Gorges Reservoir is the main reason for the change of the starting and ending time of the flood season in the lower reaches of the reservoir.