LIAO Xianwei,GAO Feng,WEI Ting,et al.基于Copula函数的松花江流域水文干旱频率分析[J].灌溉排水学报,0,():-.
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廖显薇1, 高峰2, 魏婷1, 宋小燕1, 宋松柏1
1.西北农林科技大学 水利与建筑工程学院;2.内蒙古自治区水利科学研究院
摘要:【目的】基于Copula函数对松花江流域进行水文干旱频率分析。【方法】利用可变阈值法识别日尺度水文干旱事件的历时和烈度,并进行融合处理;选择6种常用的分布函数拟合干旱特征变量,以Kolmogorov-Smirnov 检验法优选单变量边缘分布;从3种Copula函数中优选函数模型,建立了干旱历时和烈度二维联合分布,并计算联合分布概率和重现期,再利用蒙特卡洛方法,讨论基于Copula干旱研究的不确定性。【结果】融合标准取pc=0.1和tc=5,流域干旱历时均值为81~105 d;对数正态分布是大赉站、扶余站和哈尔滨站干旱历时的最优边缘分布,而各个站点干旱烈度最优分布各异; Frank Copula为流域干旱二维联合分布的最优模型,流域大多数干旱的重现期不超过20年;在同现重现期为20 a的条件下,大赉、扶余、哈尔滨和佳木斯4个水文站点的最大可能设计值表现出较大的不确定性。【结论】Copula函数能够较好地拟合松花江流域水文干旱特征变量间的联合分布,但需考虑其不确定性影响。
关键词:  水文干旱;Copula函数;干旱事件融合;松花江流域
Copula-based Analysis of Hydrologic Drought Frequency in Songhua River Basin
LIAO Xianwei1, GAO Feng2, WEI Ting1, SONG Xiaoyan1, SONG Songbai1
1.College of Water Resources and Architectural Engineering,Northwest A F University;2.Inner Mongolia Water Conservancy Research Institute
Abstract: 【Background】The occurrence of hydrological drought will have a significant impact on the water resources system of the Songhua River . Studying the frequency and uncertainty of hydrological drought is of great significance to water resources planning and drought resistance. Since univariate analysis cannot describe drought events objectively and comprehensively, it is inevitable to use Copula for multivariate analysis.【Objective】This paper analyzed the frequency of hydrological drought based on Copula in Songhua River Basin.【Method】The drought duration and severity of daily scale hydrological drought events were identified by using the Variable Threshold level Method and pooled them; The drought characteristic variables were fitted by six common distribution functions and evaluated the fitting degrees by Kolmogorov Smirnov test method. Selecting a function model from the three Copula functions, established a two-dimension joint distribution of drought characteristic variables and calculated the joint distribution probability and return period. Then, the uncertainty of drought research based on Copula was discussed by Monte Carlo method.【Result】The pooling criterion sets to pc =0.1 and tc=5, and the average drought duration is 81~105 days in Songhua River Basin; The lognormal distribution can describe the marginal distribution of drought duration well in Dalai, Fuyu and Harbin stations, but the optimal distribution of drought severity in each station is different; The Frank Copula is the optimal model for the two-dimension joint distribution of droughts. In Songhua River Basin ,the return periods of most droughts are no more than 20 years;Under the condition that the co-occurrence period is 20 years, the maximum probability design values of Dalai, Fuyu, Harbin and Jiamusi hydrological stations show greater uncertainty.【Conclusion】The Copula function can well fit the joint distribution of hydrological drought characteristic variables in the Songhua River Basin, However, the impact of uncertainty should be considered.
Key words:  hydrological drought;Copula function,;pooling of drought events; Songhua;River Basin