石家庄市城区暴雨强度公式修正方法对比分析

利用石家庄市国家基本气象站1961~2012年近52 a降水资料,基于年多个样法和年最大值法进行选样,采用皮尔逊-Ⅲ型分布对暴雨进行理论频率分析,得出暴雨强度—历时—重现期关系曲线,并利用高斯—牛顿迭代法对暴雨强度公式进行求解,以绝对标准差和相对标准差作为暴雨强度公式评价指标。结果表明:基于年多个样法推算的暴雨强度公式精度比年最大值法高,且满足暴雨强度公式评价指标。新编制的暴雨强度公式计算的暴雨强度值大部分比1978年编制的大,且随着降水历时的增长,其偏大的幅度呈增加趋势,与近30 a来石家庄市极端降水事件呈增加趋势基本相符。

Comparison of Method of Revising Urban Storm Intensity Formula in Shijiazhuang

Storm intensity formula is one of the most critical criteria for the design of retention or detention facilities and drainage sys-tems,and can directly affect their safety.In order to accommodate the increasing frequency and intensity of precipitation caused by global climate warming,the revision of storm intensity formula is necessary.In this paper the storm intensity formula in urban of Shiji-azhuang was studied based on the precipitation data during 1961 -2012.The storm cases were selected by annual multisampling and maximum methods,firstly.Then,the relations among the intensity,duration and recurrence period of storm was built by Person-Ⅲdistribution analysis.And on this basis the Gauss-Newton iterative method was applied to derive the storm intensity formula.Finally, the absolute and relative standard deviations were used to assess the fitting goodness of storm intensity formula.The results showed that the accuracy of storm intensity formula derived by using annual multisampling method was higher than that derived by using annual maximum method,and it met the evaluation indexes of storm intensity formula.The storm intensity of most precipitation processes de-rived by new formula was bigger than that derived by the formula deduced in 1978,it got bigger and bigger with the increasing of pre-cipitation duration,and it was consistent with the change trend of extreme precipitation events in Shijiazhuang city in recent 30 years. Therefore,it is necessary to study and revise the storm intensity formula with the accumulation of data and the expansion of city.