On the regularity of flood occurrences in Poyang Lake in the past 600 years

根据鄱阳湖区地方志等史料提供的信息,确定了鄱阳湖历史上无实测资料时期的洪水年份,统计分析了不同时期洪水出现次数和变化特征,揭示了鄱阳湖近600年来洪水出现的规律。;Based on the local chronicles in the lake district, the historical flood years in Poyang Lake in the past 600 years are deferred.The characteristics of the heavy flood and heavier flood occurrences are statistically analysed.The heavier flood occurrences can be summarized into three stages, namely, active (frequency P>0.416), normal (P<0.231) and interval stages (0.231≤P<0.416), as a result of which 3 active periods, 2 interval ones and 7 normal ones are obtained.Statistics also shows that both the heavier flood and heavy flood occurrences tend to mcrease with a tendency rate of 0.042 a/10a and 0.066 a/lOa, respectively.The regularity of seasonal and yearly changes are given.The historical evolution of the heavier flood occurrences in 1401-1990 has been simulated, showing a wavy fluctuation with 2 crests and 2 troughs.