Integrating Surface and Borehole Geophysics - Examples Based on Electromagnetic Sounding

By Frederick L. Paillet and John W. Lane, Jr.

Abstract

Integration of surface and borehole geophysical data is important in site characterization because there are rarely enough boreholes to effectively characterize complex aquifers, while surface soundings alone are usually too ambiguous, or lack enough spatial resolution, to provide completely noninvasive characterization. Three specific applications of logs are useful in such data integration: (1) calibration of geophysical variables, (2) definition of model layer or cell structure in the implementation of data inversion schemes, and (3) multivariate analysis of geophysical response. We demonstrate how the collective application of these three lines of approach has resulted in the successful characterization of a heterogeneous, secondary-permeability aquifer at a study site in southwestern Florida. A similar integration of surface and borehole data will be needed to effectively characterize the large-scale transport properties of bedrock aquifers buried under a thick cover of overburden such as the fractured bedrock aquifer at the Mirror Lake, New Hampshire, fractured rock field-study site.