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以径流量为水文干旱指标,通过径流量距平百分率和径流量累积频率两种方法识别水文干旱特征变量,并以适线法确定单个干旱特征变量的分布曲线,在此基础上利用Archimedean Copula函数构建了干旱历时与干旱烈度间的联合分布,并计算干旱重现期。应用研究结果表明:用Copula函数,得以上两种识别法提取的干旱历时和干旱烈度的联合概率分布,其重现期计算结果与区域实际受旱状况相符,其中径流量距平百分率法相对更优、更直观;适线法避免了基于样本数据估计分布函数参数的不合理性,使基于Copula函数的频率分析结果更可靠。
Taking the runoff as the index of hydrological drought, two characteristic variables of hydrological drought were identified by means of runoff anomaly percentage and cumulative runoff frequency, and the distribution curve of single drought characteristic variables was determined by using the fitness method. Based on this, the Archimedean Copula function The joint distribution of drought duration and drought intensity was constructed and the drought recovery period was calculated. The results of application research show that the joint probability distribution of drought duration and drought intensity extracted by the two recognition methods can be obtained by Copula function. The calculation results of the recurrence period coincide with the actual drought conditions of the area, and the runoff anomaly percentage method is relatively more Excellent and more intuitive. The fitting method avoids the irrationality of estimating the distribution function parameters based on the sample data, and makes the frequency analysis result based on the Copula function more reliable.