极端暴雨条件下暴雨频率曲线线型及参数分析

为解决极端暴雨条件下频率曲线线型及参数问题,分别采用不同偏变比P-Ⅲ型以及广义极值分布(GEV)频率曲线分析,并以山东省小清河流域为实例说明了算法适用性。利奇马暴雨在小清河重现期为120~140 a,利用R_(sv)=3.5、R_(sv)=5和R_(sv)=6三种偏变比P-Ⅲ型频率曲线,以及广义极值分布(GEV)频率曲线拟合1951年~2019年不同历时(最大24、72 h)暴雨经验点据,结果表明:上游、中游、下游最大24 h暴雨以及上游、中游最大72 h暴雨均可采用R_(sv)=3.5的P-Ⅲ型频率曲线;下游最大72 h暴雨,GEV与R_(sv)=5的P-Ⅲ型拟合效果佳且二者成果接近,工程设计中可采用R_(sv)=5的P-Ⅲ型频率曲线。

Research on Frequency Curves and Parameters of Extreme Storm

In order to solve the problems of frequency curve type and parameter selection for extreme storm research,the P-Ⅲ and GEV curves are used and applied in Xiaoqing River basin in Shandong Province to study the applicability of different algorithms. The occurrence frequency of Liqima rainstorm in Xiaoqing River is 120-140 years,and three P-Ⅲ curves with different ratios of skewness to variation( Rsv= 3. 5,5 and 6 respectively) and the GEV curve are used to fit the 1951-2019 historical data of measured rainfall. The results indicate that,( a) the maximum 24 h duration rainfall of upper reach,middle reach and lower reach and the maximum 72 h duration rainfall of upper reach and middle reach could use the P-Ⅲ curve with Rsv= 3. 5 to fit;and( b) the P-Ⅲ curve with Rsv= 5 and the GEV curve have same better fitting effect for the maximum 72 h duration rainfall of lower reach,and the P-Ⅲ curve with Rsv= 5 is proposed to be used in engineering design.