选用11种概率分布函数,系统分析了鄱阳湖流域"五河"的6个水文站年最大径流量与连续3d、7d最大平均日流量,函数参数以及拟合优度分别由线性矩法与柯尔莫哥洛夫-斯米尔诺夫方法检验,选出最适合该区流量极值分布函数.在此基础上,对引起该流域水文极值变化的原因及其影响作了有益的探讨.结果表明:(1)韦克比分布是用于研究都阳湖流域水文极值的最佳概率分布函数;(2)各水文站重现期对应的流量在水库建设前后变化并不一致,具体为建库后外洲站小于30a重现期、虎山站大于70a重现期和万家埠站小于20a重现期洪水流最发生概率小于建库前发生的概率,而其余各站点各重现期在建库后发生洪水的概率大于建库前发生的概率,这与不同支流水文气象条件以及人类活动差异性有关;(3)降雨鼍和水利枢纽工程是影响鄱阳湖流域水文极值变化的重要因素.极端降雨和降雨强度的增加是导致洪水发生概率增大的最主要的因素,水利工程特别建设在干流的大型水利设施能减少洪水流量,而森林对洪水流量的影响并不明显.%We analyzed the statistical properties of maximum mean 7-day streamflow in Lake Poyang basin using eleven probability distribution functions. Estimate of parameters was performed using the L-moment technique. Goodness-of-fit was done based on Kolmogorov-Smirnov statistic D. Mann-Kendall trend test was used to detect the trends within the streamflow extreme series. The research results indicate that: ( 1 ) Wakeby distribution is the good choice for description of the statistical behaviors of streamflow extremes in the study region; (2) Changing properties are varying from one station to another, implying different fluvial geomorphological features, climate changes and human activities; (3) Rainfall and hydraulic engineering is an important factor in effect the changes of extreme streamflow in the Lake Poyang basin. Higher frequency of hydrological and meteorological extremes may cause higher probability of floods in the study region. While hydraulic engineering, especially the construction of large-scale water conservancy facilities in the river, reduce the flood discharge. The impact of forest on flood flows is not obvious.
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