USGS Groundwater Information: Branch of Geophysics
Locating and characterizing bedrock fractures and lithologic changes is an important component of studies of ground-water supply and contamination in fractured-rock aquifers. Borehole-radar reflection methods provide information on the location, orientation, and lateral extent of fracture zones that intersect the borehole, and can identify fractures in the rock surrounding the borehole that are not penetrated by drilling. Cross-hole radar logging provides cross-sectional maps of the electromagnetic properties of bedrock between boreholes that can identify fracture zones and lithologic changes and can also be used to monitor tracer tests.
Borehole-radar logs can be integrated with results of surface-geophysical surveys and other borehole-geophysical logs, such as acoustic or optical televiewer and flowmeter, to distinguish transmissive fractures from lithologic variations or closed fractures. Integrated interpretation procedures provide results that can be used to develop conceptual and numerical models, design monitoring and sampling programs, and monitor implementation of contamination remediation measures, such as blast-fracturing.
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Citation: Singha, Kamini; Kimball, Kari; and Lane, J.W., Jr., 2000, Borehole-Radar Methods -- Tools for Characterization of Fractured Rock: U.S. Geological Survey Fact Sheet 054-00, 4 p.