基于Copula函数的抚河流域水文干旱特征分析

Analysis of Hydrological Drought Characteristics in Fuhe River Basin Based on Copula Function

探究流域干旱特征对科学防旱有着重要意义。以抚河流域为研究区,利用SWAT模型获取研究区31个子流域的径流序列并计算标准化径流指数(Standardized Runoff Index,SRI),采用游程理论和Copula函数条件概率方法对比分析流域水文干旱特征。结果表明:抚河流域在1960—2019年共发生干旱事件51次,平均干旱历时和烈度分别为4.22月和4.70;单变量因素下,流域干流附近地区发生干旱的风险较高;Frank Copula函数能较好地拟合大多数子流域的干旱两变量联合分布,重旱以上同现重现期和联合重现期均小于8 a。总体上,抚河流域发生严重干旱的风险较高,流域抗旱能力有待提高。

Exploring the characteristics of hydrological drought in watersheds is greatly significant for scientific drought prevention.In this paper,taking the Fuhe River basin as the study area,the SWAT model is used to obtain runoff sequences for 31 sub-basins in the study area and compute the Standardized Runoff Index(SRI).The tour theory and the conditional probability methods of the Copula function are applied to compare and analyze the hydrological drought characteristics in the basin.The results show that 51 drought events occurred in the Fuhe River Basin during 1960—2019,with an average drought duration and intensity of 4.22 months and 4.70,respectively.Under univariate factors,the risk of drought is relatively high in the vicinity of the mainstream of the basin.The Frank Copula function effectively fits the joint distribution of drought variables in most sub-basins,with the co-recurrence return period for severe droughts and above being less than 8 years.In general,the risk of severe hydrological drought in the Fuhe River Basin is relatively high,and the basin′s drought resistance capacity needs to be improved.