考虑历史洪水的混合分布(Historical Flood Concerned Mixed—distribution Method,HFCMM)非一致性洪水频率分析克服了样本序列长度和传统方法不考虑物理成因的不足。以武江坪石和犁市站为例,采用考虑历史洪水的L矩法估参,构建了武江非一致性年最大实测流量序列混合分布模型,并对比了厚、薄、混尾三类不同尾型分布拟合混合分布水文频率曲线的不同应用结果。结果表明:①采用不同尾型分布拟合所得水文频率曲线相对于传统结果皆存在高水尾端上翘;②厚尾分布和三参数混尾分布能在高水端提高拟合优度,而二参数混尾分布不能明显提高高水拟合效果;③采用薄尾分布拟合样本所得水文频率曲线的低水端易上翘,混合分布处理非一致性洪水序列时不宜采用薄尾分布:④HFCMM厚尾分布与三参数混尾分布相对于传统皮尔逊三型更适用于武江流域洪水频率分析。
Historical flood-concemed mixed-distribution method (HFCMM) not only extends sample length of flood runoff data but improves the traditional flood frequency analysis lacking physical ground. This study applied this method to Annual Maximum Flood(AMF) series from the Wujiang basin and developed a mixed-distribution model of annual maximum flood runoff, using historical flood-concerned L-moment for parameter estimation. Comparison of the modeling results for different Probability Distribution Function(PDF) tail types shows that HFCMM increases the recurrence intervals of high flood flows and improves their flood frequency analysis by adopting heavy-tailed or three-parameter mix-tailed PDFs but not two-parameter mix-tailed PDFs. But with thin-tailed PDFs fitting, the method reduces the recurrence intervals of low flood flows, and thus this fitting is not recommended. For flood frequency analysis of the Wujiang basin by HFCMM, the distributions of GLO and GEV fit better than the traditional Pierson Ⅲ.