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洪水极值事件在全球范围频频发生,准确估计设计流量对降低洪水灾害十分重要。洪水频率分析已广泛应用于水文设计领域,有很多被推荐的频率分布,还包括很多选择分布的准则。在北纬23.5°—66.5°之间选取4条河流——泰晤士河、沃巴什河、北江和淮河,采用极大似然法估参,并以3种分布选择准则对8种频率分布进行拟合优选。为减少可能的分布线型数量,不仅总结对比100%实测年最大日流量与分布的拟合结果,而且对在洪水频率分析中起重要作用的50%高水端实测年最大日流量进行分布拟合对比。结果表明:(1)适合100%实测流量与50%高水实测流量的最优分布基本一致但存在差别,适合50%高水流量的分布与大洪水点据拟合得更好;(2)综合考虑100%与50%高水实测流量选择最优分布,泰晤士河为Gumbel,沃巴什河是GEV和P3,北江为Weibull和GEV,淮河为Weibull;(3)为满足工程设计洪水要求,选择最优频率分布时,应综合考虑既适合100%又适合50%高水实测序列的共同分布,以减少设计洪水的不确定性。
Extreme flood events occur frequently on a global scale. Accurately estimating the design flow is very important for reducing flood disasters. Flood frequency analysis has been widely used in hydrological design, there are many recommended frequency distribution, but also includes many criteria for selection and distribution. Four rivers, the Thames, Wabash, Beijiang and Huaihe River, were chosen between 23.5 ° -66.5 ° north latitude and the maximum likelihood method was used to estimate the parameters. Eight kinds of frequency distributions were selected according to three kinds of distribution selection criteria Together preferred. In order to reduce the number of possible linear distributions, we not only summarize the fitting results of the maximum daily flow and distribution in 100% of the measured years, but also distribute the maximum daily flow of 50% of the high-water-end measured years that play an important role in the analysis of flood frequency Co-contrast. The results show that: (1) the optimal distribution for 100% measured flow and 50% measured high water is basically the same, but there is a difference. The distribution suitable for 50% Taking into account the optimal distribution of the 100% and 50% high water measured flow, the Thames River is Gumbel, the Wabash River is GEV and P3, the North River is Weibull and GEV, and the Huaihe River is Weibull. (3) In order to meet the engineering design flood demand, When choosing the optimal frequency distribution, the common distribution of 100% and 50% high-water-measured sequences should be taken into consideration to reduce the design flood uncertainty.