Wakeby分布对水文干旱指数建立的适用性分析

Applicability of Wakeby Distribution for Establishment of Hydrological Drought Index

为更准确地描述流域干旱,以汾河上游上静游站、汾河水库站的月、季、年径流量为例,计算了其对Wakeby分布、Kappa分布、广义Pareto分布、P-Ⅲ型分布拟合情况,选取最优分布,以此构建径流干旱指数SDI并进行正态标准化,对研究区的水文干旱事件进行等级划分,并依据历史记载干旱进行验证。结果表明,Wakeby分布计算得到的干旱情况与实际干旱事件基本吻合;1958~2016年间上静游、汾河水库站月尺度干旱发生频率为65%以上,以中、轻旱为主;旱情于春冬两季多发,月、季尺度干旱发生频率较稳定。Wakeby分布对于研究区径流数据有良好的适用性,其他相似地区构建干旱指数时也可将其作为参考分布。

The establishment of drought index can describe the basin drought accurately.The monthly,seasonal and annual runoff data of upstream of the Fenhe River were fitted by Wakeby distribution,Kappa distribution,Generalized Pareto distribution and P-Ⅲdistribution.Based on the optimal distribution,the runoff drought index(SDI)was established and normalized.The classified hydrological drought events were verified by historical records.The results show that the SDI established by Wakeby distribution is the best.From 1958 to 2016,the frequency of monthly drought is more than 65%in Shangjingyou and Fenhe Reservoir station.It is mainly moderate drought and mild drought.Drought often occurs in spring and winter,and the frequency of monthly and seasonal drought is stable and similar.The Wakeby distribution has good applicability for runoff data in the study area,and it can also be used as a reference distribution for other similar areas to establish drought index.