编制兰州市暴雨强度公式中频率曲线的比较

The Comparison of P-Ⅲ Pattern and Exponential Distribution on the Base of Drawing up the Rain Storm Intensity Formulation of Lanzhou City

通过对暴雨强度资料的收集、整理及计算 ,就其拟合水文频率分布的数学模型时 ,对目前工程上所采用选择的P -Ⅲ型分布与指数分布从理论上进行对比 ,得出指数分布是P -Ⅲ型分布的特殊情况 .并结合兰州市的暴雨强度资料进行了计算分析 ,得出城市暴雨强度资料统计时 ,指数分布是二参数模型 ,电算手算均容易 ,抽样误差小 ;而P -Ⅲ型分布是三参数模型 ,电算手算均费时多 ,手算精度很难以保证 ,除非获得真正的三参数最佳解以外 ,不同的计算都会有所差异 .所以城市暴雨强度资料统计时 ,采用指数分布是简便。

When the frequencies of the rain-storm intensity data are adjusted, selected P-Ⅲ pattern distribution and exponential distribution are compared in theory.Its differences is calculated and analysed on the base of the rainstorm intensity of Lanzhou city. Drawing a conclusion ,when the frequencies of the rain-storm intensity data are statistics , adopting exponential distribution is simple, feasible and accurate.