Time‐lapse electrical resistivity imaging of solute transport in a karst conduit |
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| Authors: | Audrey H Sawyer Junfeng Zhu James C Currens Clay Atcher Andrew Binley |
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| Institution: | 1. The Ohio State University, School of Earth Sciences, Columbus, OH, USA;2. University of Kentucky, Earth and Environmental Sciences, Lexington, KY, USA;3. University of Kentucky, Kentucky Geological Survey, Lexington, KY, USA;4. University of Lancaster, Lancaster Environment Centre, Lancaster, UK |
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| Abstract: | The use of electrical resistivity surveys to locate karst conduits has shown mixed success. However, time‐lapse electrical resistivity imaging combined with salt injection improves conduit detection and can yield valuable insight into solute transport behaviour. We present a proof of concept above a known karst conduit in the Kentucky Horse Park (Lexington, Kentucky). A salt tracer solution was injected into a karst window over a 45‐min interval, and repeat resistivity surveys were collected every 20 min along a 125‐m transect near a monitoring well approximately 750 m downgradient from the injection site. In situ fluid conductivity measurements in the well peaked at approximately 25% of the initial value about 3 h after salt injection. Time‐lapse electrical resistivity inversions show two broad zones at the approximate conduit depth where resistivity decreased and then recovered in general agreement with in situ measurements. Combined salt injection and electrical resistivity imaging are a promising tool for locating karst conduits. The method is also useful for gaining insight into conduit geometry and could be expanded to include multiple electrical resistivity transects. Copyright © 2015 John Wiley & Sons, Ltd. |
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| Keywords: | karst groundwater electrical resistivity hydrogeophysics tracer |
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