High‐resolution characterization of hydraulic properties and dense nonaqueous phase liquid (DNAPL) contaminant source is crucial to develop efficient remediation strategies. However, DNAPL characterization suffers from a limited number of borehole data in the field, resulting in a low‐resolution estimation. Moreover, high‐resolution DNAPL characterization requires a large number of unknowns to be estimated, presenting a computational bottleneck. In this paper, a low‐cost geophysical approach, the self‐potential method, is used as additional information for hydraulic properties characterization. Joint inversion of hydraulic head and self‐potential measurements is proposed to improve hydraulic conductivity estimation, which is then used to characterize the DNAPL saturation distribution by inverting partitioning tracer measurements. The computational barrier is overcome by (a) solving the inversion by the principal component geostatistical approach, in which the covariance matrix is replaced by a low‐rank approximation, thus reducing the number of forward model runs; (b) using temporal moments of concentrations instead of individual concentration data points for faster forward simulations. To assess the ability of the proposed approach, numerical experiments are conducted in a 3‐D aquifer with 10⁴ unknown hydraulic conductivities and DNAPL saturations. Results show that with realistic DNAPL sources and a limited number of hydraulic heads, the traditional hydraulic/partitioning tracer tomography roughly reconstructs subsurface heterogeneity but fails to resolve the DNAPL distribution. By adding self‐potential data, the error is reduced by 24% in hydraulic conductivity estimation and 68% in DNAPL saturation characterization. The proposed sequential inversion framework utilizes the complementary information from multi‐source hydrogeophysical data sets, and can provide high‐resolution characterizations for realistic DNAPL sources.

中文翻译：

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通过水力头，自电势和分区示踪剂数据的顺序水文地球物理反演，改进对DNAPL源区的表征

水力学特性和致密非水相液体（DNAPL）污染源的高分辨率表征对于制定有效的补救策略至关重要。但是，DNAPL表征受限于现场有限数量的井眼数据，从而导致低分辨率估算。此外，高分辨率DNAPL表征需要估计大量未知数，这带来了计算瓶颈。在本文中，一种低成本的地球物理方法，即自势方法，被用作表征水力特性的附加信息。提出了对水头和自电位测量值进行联合反演的方法，以改进对水力传导率的估算，然后通过反演分区示踪剂测量值来表征DNAPL饱和度分布。通过以下方法克服计算障碍：（a）用主成分地统计方法解决反演问题，在该方法中，协方差矩阵被低秩近似代替，从而减少了正向模型的运行次数；（b）使用浓度的瞬时矩代替单个浓度数据点进行更快的正向模拟。为了评估所提出方法的能力，在3D含水层中进行了10个数值实验。^4个未知的水力传导率和DNAPL饱和度。结果表明，在现实的DNAPL来源和有限的液压头的情况下，传统的液压/分区示踪剂层析成像可以大致重建地下异质性，但无法解析DNAPL的分布。通过添加自电位数据，在水力传导率估算中的误差降低了24％，在DNAPL饱和度表征中的误差降低了68％。拟议的顺序反演框架利用了来自多源水文地球物理数据集的补充信息，并可以为现实的DNAPL源提供高分辨率的表征。