鄱阳湖流域天然径流变化特征与水旱灾害

Natural runoff change characteristics and flood/drought disasters in Poyang Lake catchment basin

为探讨鄱阳湖流域河川径流的变化过程和规律,深入了解径流特征及其与鄱阳湖水旱灾害的关系,利用时间序列分析方法,对鄱阳湖流域五河水系干流河段主要控制水文测站的天然径流系列进行了研究。研究显示,鄱阳湖五河径流年内分配集中程度在0.43到0.56之间,集中期为每年的5月底6月初,比鄱阳湖汛期提前1-2个月。径流多年变化变差系数变化在0.28～0.33之间,径流年际变率较大,在年代际变化上20世纪90年代径流增加尤其突出;径流序列呈长期的增加趋势,1998年后增加趋势变缓;鄱阳湖流域五河水系出现特大枯水年和丰水年的概率较大,出现平水年的概率略小。以上结果表明,五河汛期来水是影响鄱阳湖洪水的重要因素,而其形成、发展过程还受到长江中上游洪水的控制;径流的长期变化中,气候因素是引起鄱阳湖流域径流变化主导因素,水土流失和水利工程的建设等人为因素起着一定的辅助作用;径流序列枯、丰循环周期的交替变化过程,与过去几十年间流域内出现的干旱、洪水现象具有较好的一致性。

In order to better understand the variations of surface runoff and the relationship between runoff and flood/ drought in Poyang lake catchment basin, time series analysis was performed for eight stream flow gauging stations loca- ted at five main rivers in the catchment basin. The results show that, the distribution of annual runoff is uneven with a moderate annual concentration between 0.43 and 0.56, and concentration period is between the end of May and the early of June, which is one or two months before the flood period of Poyang Lake. There is great variation of yearly surface runoff, with variation coefficient ranging from O. 28 to 0.33. The long-term annual runoff sequences in main rivers dent- onstrate a constant increase trend, especially after 1990s, when the increase trend is more obvious. Frequency of enor- mously wet and dry year is relatively high in that area, but low for normal hydrological year, which implies that Poyang Lake catchment basin is more frequent to encounter drought and flood disasters. The study of this paper indicate that the flood of Poyang Lake is mostly influenced by the recharge front the five river subcatchment at flood season , but controlled by the flood from the upper and middle reaches of Yangtze River. The long-term trend of stream runoff is controlled by the variation of climate changes, and impacted by human activities in the catchment basin. Circulation and dry years gives a clear illustration of the drought and flood events in the last five decades of 20th century.