年径流变差系数CVR经验公式及其参数的地理综合

在涉水工程设计初期,需要对涉水工程的设计年径流进行分析计算,以确定工程不同保证率的正常年来水量,从而指导工程运行管理过程中的兴利调节。而设计年径流分析计算的核心就是计算设计流域年径流3个统计参数,即:年径流均值、变差系数和偏态系数。对于有实测资料的设计流域来讲,上述3个统计参数可通过对实测资料进行频率分析计算确定。对于无实测资料的设计流域,一般通过经验公式求得。现介绍了山西省无资料地区设计年径流变差系数CVR经验公式形成过程以及参数的地理综合。引入了流域气候特点和下垫面条件对CVR经验公式中各种参数的影响,提出了不同水文分区参数的综合结果。并通过对已有实测资料的水文站点进行演算,对误差进行了分析对比,从误差统计结果看,年径流变差系数CVR经验公式以及参数其计算精度能满足无资料地区设计年径流变差系数的求算。

Empirical Formula of the Coefficient of Variation CvR of Annual Runoff and its Parameters in Geographical Synthesis

At the beginning of the construction design of the water-related project,the design annual runoff of the water-related project needs to be analyzed in order to determine the inflow of the project with different engineering guarantee rates,which is used to provide guidance for the profiting regulation in the engineering operation.The core of design annual runoff is to calculate and design three statistical parameters in annual runoff,including the average annual runoff,the coefficient of variation,and the coefficient of skewness.For the areas with observed data,the three statistical parameters can be obtained from the observed data using the frequency analysis.For the areas without observed data,the three statistical parameters are usually determined by the empirical formula.This paper introduces the development of the empirical formula to determine the coefficient of variation(C_VR) of the design annual runoff and the geographical synthesis of this parameter in an area without observed data in Shanxi province.In development of the empirical formula,the climatic characteristics of the river basin and the effects of underlying surface conditions on C_VR are considered,and the results of the parameters in different hydrological zones are also investigated.The formula is used to calculate the values of C_VR at the hydrological stations with observed data,and the calculated and observed C_VR are compared.The results show that the proposed empirical formula is applicable to determine the coefficient of variation(C_VR) of the design annual runoff for the areas without observed data.