城市雨水池设计雨量公式的统计方法

Statistical Method Study on Rainfall Depth Formula for Urban Rainwater Tank

基于北京市53 a的日降雨量资料,分别采用年最大值、年超大值、年超定量和年多个值法进行选样对比,并用频率曲线(对数正态分布、皮尔逊Ⅲ型分布、对效皮尔逊Ⅲ型分布、耿贝尔分布)进行拟合.理论频率曲线的参数估计采用矩法.各种分布的拟合优度检验采用x^2检验法和K-S检验法.拟合准则采用离差平方和最小的原则.拟合各种选样方法数据,皮尔逊Ⅲ型分布函数拟合误差最小.在资料年数不长或需要计算小于1a重现期的情况下,建议采用年多个值法,否则采用年最大值法、皮尔逊Ⅲ型分布拟合最佳.

Based on 53 years observed data of rainfall in Beijing, the annual maximum series method, the annual exceedance series method, the partial duration series （rainfall depth over threshold） method and the annual multi-sampling series method were separately used to process rainfall depth data. Four candidate distributions （log normal, Pearson Ⅲ, log Pearson Ⅲ and Gumbel） were used to fit the observed data and find the most appropriate distribution. Distribution parameters were estimated using the moment method. The assessment was based on the Chi-Squared test and Kolmogorov-Smirnov test combined with root mean squared error. On the basis of these comparisons and estimation results, it can be concluded that, if the length of rainfall records is shorter or selected return period is less than one year, the annual multi-sampling series method is proposed, otherwise, the annual maximum series method is proposed. The Pearson m distribution is the most appropriate distribution for Beijing rainfall data.