极限水文干旱历时概率分析

An analysis of frequency of critical hydrologic drought duration

本文用枚举法导出了独立同分布的随机变量序列的最大负游程长的概率分布函数，并将其用于相应序列的极限干旱历时（最大干旱持续时间）的概率分析．应用结果显示，本文介绍的独立同分布的随机变量序列的最大负游程长的概率分布函数，将其最大负游程长作为极限于旱历时，与相应结构的年径流序列在各种频率对应的流量截取后得到的水文干旱最大持续时间序列的经验频率拟合良好．因此可将这一概率分布函数称为极限干旱概率分布函数．将其用于由具有独立结构的年降水序列表证的气候干旱，也可得到良好的结果．

In this paper, the probability distribution function of the maximum negative run length in an independently and identially distributed random variance series was derived using the enumeration technique. The basic characteristics of the function was analyzed and also used to analyze the probability distribution features of critical multi-year hydrologic drought durations extracted from statistically independent annual stream flow series. The selected annual stream now data for the analysis are those from six hydrologic gauges with relatively long records in the Wei River, the Jing River and the North Luo River. All the stream flow series have independently and identially distributed structures at the confidence level of 90%. The results show that the probability distribution function of the maximum negative run length can be used as the probability distribution function of the critical hydrologic drought durations, which is in good fitting with the empirical frequency of the maximum persistent years of the droughts (critical drought durations), obtained after truncating the corresponding structural annual stream flow series from the six gauges by corresponding flows of various frequencies. The probability distribution function may also be used in the analysis of other kinds of persistent droughts such as climatological and agricultural droughts.