BIRDSALL-DREISS DISTINGUISHED LECTURE: TOWARD X-RAY VISION: GEOPHYSICAL SIGNATURES OF COMPLEX SUBSURFACE PROCESSES

Developing a predictive understanding of water and contaminant fate and transport is complicated by natural heterogeneity, as well as by the disparity of scales across which hydrological, geochemical, and microbiological processes dominate. Because some geophysical attributes are sensitive to hydrological and biogeochemical properties that govern flow and transport, geophysical methods hold potential for minimally invasive characterization and monitoring of complex subsurface processes.

This 2010 GSA Birdsall-Dreiss Distinguished lecture will describe the relatively new fields of hydrogeophysics and biogeophysics, which strive to use geophysical datasets to characterize subsurface hydrogeological and biogeochemical processes, respectively. Several key components are required for such quantitative characterization, including: high quality geophysical datasets, petrophysical models, frameworks to integrate disparate datasets, and attention to scale issues. This presentation will review these key components and present several examples that illustrate how hydrogeophysical and biogeophysical methods can be used to gain significant insights about complex subsurface system processes, such as subsurface bacterial transport and feedbacks between biogeochemical transformations and flow characteristics. A particular emphasis will be placed on processes relevant to environmental remediation, where in-situ treatments (such as bioremediation) significantly disrupt geochemical equilibrium and where developing a predictive understanding of remediation-induced transformations is difficult to develop using wellbore data alone.