地下水可开采系数计算结果的可靠度与敏感性

Reliability and sensitivity analysis of calculated results of allowable withdrawal coefficient of groundwater

为了分析地下水可开采系数计算结果的可靠程度及其对模型参数的敏感性,从参数存在的不确定性角度出发,采用蒙特卡罗方法对地下水可开采系数进行可靠度分析,结合实例定量分析了包气带对降水的有效利用系数αp、降水入渗补给系数αg、作物对潜水蒸发的有效利用系数C、给水度μ和灌溉回归系数β等5个参数的不确定性对地下水可开采系数计算结果的影响,分析了不同可靠度对应可开采系数(可开采量)的变化规律,并阐述了不同离势系数对可开采系数计算结果的影响.结果表明:参数服从正态分布时50%可靠度对应的可开采量比参数取均值时的可开采量小;地下水可开采系数计算结果对模型参数的敏感性排序从大到小为αg,αp,μ,β,C.

In order to analyze the reliability of the calculated results of the allowable withdrawal coefficient of groundwater and their sensitivity to model parameters,the reliability analysis of the allowable withdrawal coefficient of groundwater was performed based on the uncertainty of parameters by use of the Monte Carlo method.Through a case study,the influences of the uncertainty of 5 parameters on the calculated results of the allowable withdrawal coefficient of groundwater were quantitatively analyzed,including effective water efficiency of precipitation in aeration zone αp,feed coefficient of precipitation infiltration αg,effective water efficiency of evaporation from phreatic water by crops C,specific yield μ and regression coefficient of irrigation β.The variation rules of the allowable withdrawal coefficients （allowable withdrawal） under various reliabilities were discussed.The influences of different dispersion coefficients on the calculated results of the allowable withdrawal coefficient were investigated.The results indicate that when the parameters obey the normal distribution,the allowable withdrawal under the reliability of 50% is smaller than that under the average value.The calculated results of the allowable withdrawal coefficient of groundwater are sensitive to the parameters in the order of αg,αp,μ,β and C.