基于Monte Carlo方法的地表水地下水耦合模拟模型不确定分析

为分析参数的不确定性对地表水地下水耦合模拟模型输出结果的影响,本文运用Monte Carlo方法对地表水地下水耦合模拟模型进行不确定性分析,并根据不确定性分析结果进行生态恶化风险评估。以石头口门水库上游饮马河汇水流域为例,建立地表水地下水耦合模拟模型,并运用HydroGeosphere(HGS)软件求解。利用局部灵敏度分析方法甄选出耦合模拟模型中灵敏度较高的参数,作为随机变量。最后,运用Monte Carlo方法对耦合模拟模型进行不确定性分析。为了减少不确定性分析过程中的计算负荷,应用Kriging方法,建立耦合模拟模型的替代模型。结果表明:地表水地下水耦合模拟模型中灵敏度较高的参数为渗透系数、孔隙度和曼宁粗糙系数,其中渗透系数的变化不仅对耦合模型中地下水水位产生影响,也对地表水流量产生影响;Kriging替代模型可以在保证一定精度的条件下大幅度减少计算负荷;风险评估结果表明,在当前的水资源开发利用条件状态下,研究区地下水生态环境恶化风险的概率为6%,地表水生态环境恶化风险概率为15%。

Uncertainty analysis of surface water and groundwater coupling simulation model based on Monte Carlo method

In order to analyze the influence of the uncertainty of the parameters on the output results of the surface water and groundwater coupled simulation model,this paper uses the Monte Carlo method to analyze the uncertainty of the surface water and groundwater coupling simulation model, and carries out the risk assessment on the basis of the results of uncertainty analysis. In this paper, the coupling simulation model of surface water and groundwater is established by taking the water catchment of the Yin Ma River in the upper reaches of the Shitoukoumen Reservoir as example, and the HydroGeosphere (HGS) software is used to solve the model. Local sensitivity analysis method is used to identify the parameters with high sensitivity in the coupled simulation model as random variables. Then the Monte Carlo method is applied to analyze the uncertainty of the simulation model. In order to reduce the computational load in the process of uncertainty analysis, a surrogate model of simulation model is established by using Kriging method. The results show that the most sensitive parameters in the coupling model of surface water and groundwater are hydraulic conductivity, porosity and Manning roughness coefficient. The Kriging surrogate model can significantly reduce the computation load under certain accuracy. The risk assessment results show that the risk probability of groundwater ecological environment deterioration is 6%, and the probability of surface water environment deterioration is 15%.