特枯2006年长江中下游径流特征及江湖库径流调节过程

利用1978特枯年、2000~2006年长江中下游宜昌、汉口、大通、城陵矶及湖口等水文实测资料,对2006年长江中下游出现特大枯水水情条件下的径流变化和江、湖与水库的调节过程进行分析。结果表明:长江中下游径流变化出现洪季不洪、枯季不枯特征,洪季来水量不到平常年的60%~70%,枯季基本维持平常年的来水量;其中长江上游来水量急剧减少是造成长江中下游洪季不洪的主要因素,三峡在枯水期间的调蓄对维持长江中下游干流的水量有一定的贡献,洞庭湖与鄱阳湖两大湖泊在枯季因干流水位显著降低形成的胁迫效应是长江中下游枯季不枯的重要因素。

Adjustment Processes of Runoff Among River,Lake and Reservoir Along Mid-lower Reaches of Changjiang River During 2006 Extreme Drought Year

Lakes are important water supplies to the discharge of the mid-lower reaches of the Changjiang (Yangtze) River (MLRCR), which take vital function of adjuster in maintaining constant runoff of the mainstream in the Changjiang River. Based on the measured hydrological data, during 1978 extreme drought year and 2000-2006, of the gauge stations including Yichang, Datong, Hukou and Chenglingji, the change of runoff along the MLRCR and water adjustment processes among of river, lake and reservoir in response to abnormal historical record of the 2006 extreme drought year were analyzed. The results showed that it could be characterized as "no flood in the flood season, no drought in the dry year" for the changes of runoff along the MLRCR. During the period of 2006 year, there was usual water flux in the dry season along the MLRCR in comparison with those of normal years, and the water flux in the flood season was only 60%-70% of normal years. "No flood in the flood season" results from rapid decreases in runoff of the upper reaches of the Changjiang River. In addition, it was benefit to the increased water flux to some degree in the MLRCR due to the adjustment of the Three Gorge Reservoir. However, supplies and adjusted function from Dongting and Poyang lakes resulted from constraint effects by obvious decrease in water level in the stream was an important part to the MLRCR in maintaining the runoff characteristics of "no drought in dry season".