非饱和土壤渗透系数空间不确定性对溶质运移的影响

Effect of spatial uncertainty of unsaturated zone permeability coefficient on solute transport

包气带渗透系数的不确定性是影响非饱和带溶质运移的主要因素。应用贝叶斯方法对非饱和土壤渗透系数进行前处理,使用Monte-Carlo方法模拟其空间不确定性,并通过HYDRUS-1D模型对溶质运移进行数值模拟,研究包气带渗透系数的空间不确定性对溶质运移的影响。结果表明,由于包气带渗透性的不确定性使得溶质浓度分布呈现明显的不确定性,包气带内不同点的浓度值相差很大。与忽略包气带土性参数空间不确定性的模拟结果相对比,考虑包气带渗透系数不确定性的模拟结果与实际情况更加接近,更具合理性和科学性。同时,根据模拟结果,对实际工作中进行地下水数值模拟时溶质初始浓度输入值的确定提出相应建议。

Spatial uncertainty of permeability is the primary factor which has significant impact on solute transport in unsaturated zone. In this study,Bayesian method was used in pre-processing of permeability coefficients and Monte Carlo method was used to simulate spatial uncertainty of permeability coefficients. Numerical model of HYDRUS-1D was used to simulate the solute migration in the unsaturated zone taking spatial uncertainty of permeability coefficient into account. The results showed that the distribution of solute concentration presented a significant uncertainty,and compared with the case of ignoring spatial uncertainty of permeability coefficients in unsaturated zone,it is more closer to the actual situation. Meanwhile,some suggestions about the value of initial concentration in numerical simulation of groundwater are given combining the simulation results.