Hydraulic Tomography in Highly Heterogeneous Geologic Media: Field and Computational Investigations

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Information about subsurface hydraulic parameters is critical for thorough understanding of fluid flow and contaminant transport processes. A detailed understanding of these processes is necessary for the evaluation of groundwater supplies, groundwater remediation, extraction of fossil fuels, evaluation of nuclear waste disposal sites, and in situ leaching of metals, etc. However, the subsurface is heterogeneous at multiple scales and this significantly complicates our understanding of these processes. Hydraulic tomography (HT) is rapidly emerging as a new method to image the subsurface heterogeneity of both hydraulic conductivity (K) and specific storage (Ss). HT is different from geophysical tomography, as the former relies on pumping or injection of water as a source of excitation, while the latter relies on electromagnetic signals as sources. While HT has been shown to be a promising method for imaging subsurface heterogeneity, there is a critical need to examine whether: 1) other site data can improve HT results; 2) HT can be effective at larger scales; and 3) HT is effective in fractured rock terrains. Therefore, we will first examine the effectiveness of fusing other site data (e.g., geological, geophysical and geochemical) with pumping test data on HT results. Next, this project will examine the feasibility of conducting HT surveys at a considerably larger scale (100's to 1000's m) than previously attempted. Lastly, this project will also examine the applicability of HT to fractured rocks. Collectively, these research projects will help determine whether HT can significantly improve subsurface characterization efforts relevant at the resolution and scale necessary for various industries (water, remediation, energy, mining, etc.). The proposed research focuses on conducting complementary field and computational investigations that should significantly advance our capabilities to map subsurface heterogeneity in porous and fractured geologic media. Development of such capabilities will also allow us to significantly advance our fundamental understanding of fluid flow and contaminant transport processes in highly heterogeneous geologic media.