Hydraulic conductivity and porosity heterogeneity controls on environmental performance metrics: Implications in probabilistic risk analysis
Hydraulic conductivity and porosity heterogeneity controls on environmental performance metrics: Implications in probabilistic risk analysis
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DOI：
10.1016/j.advwatres.2019.03.002
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发表时间：
2019-05
影响因子：
4.7
通讯作者：
Arianna Libera;C. Henri;F. D. de Barros
中科院分区：
文献类型：
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作者：
Arianna Libera;C. Henri;F. D. de Barros
天然多孔地层的非均质性主要通过水力传导率 (K) 和较小程度的孔隙度 (ψ) 表现出来，在很大程度上控制着地下流动和溶质运移。 K 的异质结构对输运过程的影响已被广泛研究，而对电导率场和孔隙度场的联合异质性的关注较少。我们的研究采用蒙特卡罗模拟来研究 K− ψ 空间变异性对 3D 含水层域内保守羽流和反应羽流的传输行为（和不确定性）的耦合影响。我们探索了以不同程度的地质性质异质性为特征的多种场景，并将联合 K− phi 异质系统的计算结果与普遍采用的恒定 phi 条件下的结果进行比较。在我们的研究中，空间变量 K− ψ 场呈正相关。我们对关键的环境绩效指标进行统计分析：非反应性物质的首次到达时间和峰值质量通量以及反应性氯化溶剂的终生癌症风险增加。保守的输运模拟表明，考虑耦合 K− ψ 场会降低羽流扩散，增加溶质的首次到达时间和观测平面的峰值质量通量。对于均质和非均质 phi，含水层连通性与峰值质量通量之间存在正相关关系。我们保守的输运结果表明， ψ 变异性的相关性可能取决于感兴趣的度量、控制平面-源距离以及电导率场的异质性水平。对反应性运输的分析表明，ψ 变异仅轻微影响控制平面上平均增加的终生癌症风险，但会导致癌症风险不确定性的显着降低。我们还发现，癌症风险对 phi 异质性的敏感性可能受到电导率场变异水平、源到控制平面距离的影响，但不受污染物浓度计算方式的影响。
Heterogeneities in natural porous formations, mainly manifested through the hydraulic conductivity (K) and, to a lesser degree, the porosity (ϕ), largely control subsurface flow and solute transport. The influence of the heterogeneous structure of K on transport processes has been widely studied, whereas less attention is dedicated to the joint heterogeneity of conductivity and porosity fields. Our study employs Monte Carlo simulations to investigate the coupled effect of K− ϕ spatial variability on the transport behavior (and uncertainty) of conservative and reactive plumes within a 3D aquifer domain. We explore multiple scenarios, characterized by different levels of heterogeneity of the geological properties, and compare the computational results from the joint K− ϕ heterogeneous system with the results originating from generally adopted constant ϕ conditions. In our study, the spatially variable K− ϕ fields are positively correlated. We statistically analyze key Environmental Performance Metrics: first arrival times and peak mass fluxes for non-reactive species and increased lifetime cancer risk for reactive chlorinated solvents. The conservative transport simulations show that considering coupled K− ϕ fields decreases the plume dispersion, increases both the first arrival times of solutes and the peak mass fluxes at the observation planes. A positive correlation between aquifer connectivity and peak mass fluxes is identified for both homogeneous and heterogeneous ϕ. Our conservative transport results indicate that the relevance of ϕ variability can depend on the metric of interest, the control plane-source distance as well as the level of heterogeneity of the conductivity field. The analysis on reactive transport shows that ϕ variability only slightly affects the mean increased lifetime cancer risk at the control planes but leads to a considerable reduction of the cancer risk uncertainty. We also see that the sensitivity of cancer risk towards ϕ heterogeneity can be influenced by the level of variability of the conductivity field, the source-to-control plane distance, but is not affected by the manner in which the contaminant concentration is computed.