推理公式计算淤地坝设计洪峰时暴雨递减指数取值研究

Study on Storm Decline Index in Rational Formula Used in Design Flood Peak of Warping Dam

推理公式法是现行淤地坝设计洪峰计算的主要方法,推理公式法中的暴雨递减指数n的取值具有随历时、频率、点面雨量不同而变化的特点,n的取值对淤地坝设计洪峰的计算结果具有较大影响。淤地坝地处小流域,洪水汇流时间短,一般小于1 h,其洪峰由超短历时雨峰形成,在运用推理公式法计算淤地坝设计洪峰流量时,应选取由10 min、1 h时段的点雨量资料分析得出的相应频率的暴雨递减指数值,才能计算出合理的洪峰流量值。

Rational formula is the main method used in design flood calculation of warping dam.The storm decline index(n for short)in ra⁃tional formula is changed with the time interval,frequency,and the point or area rainfall.The value of n influences the calculation result of design flood peak of warping dam.The warping dam is usually located in small watersheds with short flood confluence time which is less than one hour.As the flood peak is formed from the storm peak at very short time,the value of n should be n1 with corresponding frequency,which is analyzed from the point storm of ten minutes and one hour in order to calculate the reasonable peak discharge value.