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以汾河上游四个水文站月径流资料为基础,选取常用的六种概率分布拟合了月、季、年时间尺度下的径流量,并进行了拟合优度检验,判断出汾河上游水文站不同时间尺度下径流服从的最佳分布函数,根据最佳分布函数计算标准化径流指数,分析不同时间尺度下的水文干旱时空变化特征。结果表明,汾河上游不同站点在不同时间尺度下服从的概率分布并不统一;不同时间尺度下四个水文站的标准化径流指数变化具有较好的一致性;1956~2000年标准化径流指数总体呈下降趋势,水文干旱逐年加重;西北部干旱程度逐渐减轻,东南部干旱严重程度逐渐加重。
Based on the monthly runoff data of the four hydrological stations in the upstream of Fen River, six commonly used probability distributions were fitted to monthly, quarterly and annual runoff, and the goodness of fit test was conducted to determine the upper reaches of Fen River The optimal distribution function of runoff obey under different time scales of hydrological stations is calculated, and the standard runoff index is calculated according to the optimal distribution function to analyze the spatio-temporal variations of hydrological drought under different time scales. The results show that the probability distributions obeyed by different stations in the upper reaches of Fenhe River are not uniform under different time scales. The standardization runoff indices of four hydrological stations at different time scales are in good agreement. The standardization runoff indices from 1956 to 2000 are generally In the downward trend, the hydrological drought aggravates year by year; the drought in the northwest gradually reduces and the severity of the drought in the south-east gradually aggravates.