基于PPCC检验的径流指数对汾河上游水文干旱演变分析

Hydrologic Drought Evolution Analysis of Upper Fenhe River by Streamflow Index Based on PPCC Approach

水文干旱处于气象与农业干旱之间,影响着社会经济干旱。根据概率点据相关系数法检验汾河上游年径流对P-Ⅲ、对数P-Ⅲ及二参数对数正态分布的拟合情况,采用最佳分布计算径流干旱指数,分析汾河上游水文干旱变化趋势。结果表明,汾河上游年径流最佳拟合分布为二参数对数正态分布。随着时间的推移,汾河上游无旱持续时间变短,干旱持续时间延长,且发生干旱的趋势性显著。其中,不同程度干旱发生的可能性最大为轻旱,其次为中旱、重旱及特旱发生可能性较小且概率相当。

Hydrologic drought is in the midst of meteorological drought and agrieultural drought, and affects the society economy drought. The best fitting distribution for annual runoff of upper Fenhe River from P-III distribution, logarithmic P-III distribution and two parameters of logarithmic normal distribution is tested based on the approach of probability plot correlation coefficient, and a runoff drought index is obtained by using the best probability distribution function to analyze the hydrologic drought trend of upper Fenhe River. The results show that the annual runoff of upper Fenhe River fits two parameters of logarithmic normal distribution very well. Over time, the duration of non-drought is shorter while that of drought is longer than ever, and the trend of having drought events in upper Fenhe River is obvious, in which, the mild drought is most likely to happen, the next is moderate drought and the probability of severe drought and extreme drought is equal but very small.