暴雨衰减指数为函数型的暴雨强度公式确定方法

暴雨强度公式是城镇排水工程设计的基本依据之一。为提高暴雨衰减指数随重现期显著变化时暴雨强度公式的拟合精度,结合实例研究了采用麦夸尔特法确定衰减指数为函数型的五参数暴雨强度公式的方法。计算结果表明,五参数暴雨强度公式能显著提高拟合精度,由该公式计算的残差平方和及各重现期的绝对均方差(即标准差)均明显小于四参数公式的计算结果,其各重现期的绝对均方差均小于0.05mm/min。该方法能有效降低重现期较小与较大时的绝对均方差。此外,给出了麦夸尔特法的计算程序框图,为编写计算程序代码奠定基础。

Determining method of storm intensity formula with the functional storm attenuating index

Storm intensity formula is one of the basic bases in the field of urban drainage engineering design.In order to improve the fitting accuracy of storm intensity formula when the storm attenuating index varies significantly with recurrence interval,combing the practical case study,this paper studied the determining way,which used Marquardt method,for five-index storm intensity formula with the functional storm attenuating index.The calculation results showed: five-index storm intensity formula could improve the fitting accuracy apparently;both the residual sum of squares and the absolute root mean square deviation(i.e.standard deviation) in the calculation of this formula were significantly less than the calculation of four-index storm intensity formula;standard deviation of the every recurrence interval was less than 0.05 mm/min.This method could decrease the standard deviation at relatively small or big recurrence intervals.In addition,calculation program block diagram of Marquardt method was proposed,which could provide basis for writing program code.