基于含水层非均质性随机特征的地下水脆弱性评价

由于地质条件的复杂性,人们所能获取的地质和水文地质资料是有限的,这就导致对水文地质条件的认识具有不确定性,其中以含水层非均质特征最为显著,这对地下水脆弱性评价显然会产生显著的影响。考虑含水层的非均质特性,提出具有非平稳随机场空间相关性的地下水脆弱性评价方法。以南京市江宁区中部地区为例,用改进的连续随机增加方法(Successive Random Additional method,简称SRA)生成了渗透系数对数(lnK),具有分维Levy运动统计特征的随机场,模拟含水层渗透系数可能的非均质空间分布,采用DRASTIC方法进行地下水脆弱性评价。结果表明由此方法生成的渗透系数场变化的程度相对传统的普通克里金方法更加剧烈,更加符合复杂分布的非平稳随机场特征,在此基础上建立的地下水脆弱性评价更加符合客观事实,丰富和发展利用随机理论解决地下水环境问题的理论和方法。

Groundwater Vulnerability Assessment Based on Random Characteristics of Aquifer Heterogeneity

Due to the complexity of geological conditions, the geological and hydrogeological data available to the people arelimited,which leads to the uncertainty in the understanding of hydrogeological conditions. Among them, the heterogeneity of aquifersis the most significant one, which would have a significant impact on the assessment of groundwater vulnerability. This paperconsidered the heterogeneity of aquifers and proposed a groundwater vulnerability assessment method with non -stationary random space spatial correlation. Taking the central area of Jiangning district in Nanjing as an example, a modified successive randomadditional method (SRA) was used to generate a random field with fractional Levy motion statistics for the logarithm of hydraulicconductivity (lnK),and the possible non -homogeneous spatial distribution of the hydraulic conductivity was simulated,and theDRASTIC method was used to evaluate groundwater vulnerability.The results show that the degree of change in the hydraulicconductivity field generated by SRA is more severe than that of the conventional ordinary Kriging method,and it is more in linewith the characteristics of complex distributed non-stationary random fields. The groundwater vulnerability assessment established onthis basis is more in line with objective facts,which enriches and develops theories and methods in using stochastic theory to solvegroundwater environmental problems.