USGS Groundwater Information: Branch of Geophysics
Dept. of Geosciences, Penn State University, 311 Deike Building, University Park, PA 16802
Branch of Geophysics, U.S. Geological Survey, 11 Sherman Place, Storrs, CT 06268
Traditionally, interpretation of geophysical tomograms for geologic structure or engineering properties has been either qualitative, or based on petrophysical or statistical mapping to convert tomograms of the geophysical parameter (e.g., seismic velocity, radar velocity, or electrical conductivity) to some hydraulic parameter or engineering property of interest (e.g., hydraulic conductivity, porosity, or shear strength). Standard approaches to petrophysical and statistical mapping do not account for variable geophysical resolution, and thus it is difficult to obtain reliable, quantitative estimates of hydrologic properties or to characterize hydrologic processes in situ. Recent research to understand the limitations of tomograms for quantitative estimation points to the need for data integration. We divide near-surface geophysical data integration into two categories: 'inversion-based' and 'post-inversion' approaches. The first category includes 'informed-inversion' strategies that integrate complementary information in the form of prior information; constraints; physically-based regularization or parameterization; or coupled inversion. Post-inversion approaches include probabilistic frameworks to map tomograms to models of engineering properties, while accounting for geophysical resolution, survey design, heterogeneity, and physical models for hydrologic processes. Here, we review recent research demonstrating the need for, and advantages of, data integration. We present examples of both inversion-based and post-inversion data integration to reduce uncertainty, improve interpretation of near-surface geophysical results, and produce more reliable predictive models.
Final copy as submitted to the American Geophysical Union for publication as: Day-Lewis, F.D., and Singha, Kamini, 2007, Data integration for interpretation of near-surface geophysical tomograms: EOS Transactions, American Geophysical Union, v. 88, no. 52, Fall Meeting Supplement, Abstract NS43A-01 Invited.