2012 NGWA Ground Water Summit: Innovate and Integrate

A New Thermal Method for Characterizing Groundwater Flux Variations

Tuesday, May 8, 2012: 3:30 p.m.
Royal Ballroom A (Hyatt Regency Orange County)
Steve Knobbe, University of Kansas;
Gaisheng Liu, University of Kansas;
James J. Butler Jr., University of Kansas;
Edward C. Reboulet, University of Kansas;

Groundwater flux has long been recognized as the most critical factor controlling the transport of contaminants in aquifer systems. A major challenge has been to develop field methods that allow information about groundwater flux variations to be obtained at the resolution needed for reliable risk assessment and remediation activities at contaminated sites. Recently, we have developed a new thermal method that holds considerable promise for obtaining high-resolution, continuous information about groundwater flux in an efficient fashion.  This new approach, which is based on the previously proven concept of using a heat tracer to track groundwater movement and the development of fiber optic distributed temperature sensing (FO-DTS) technology for hydrologic applications, uses a tool that is placed in an existing well. The approach was applied at a field site located in the floodplain of the Kansas River in the central United States. The thermal profiles obtained using this method are remarkably consistent with hydraulic conductivity (K) profiles obtained through other means at the same well, and provide new insights into the factors controlling the relatively large K variations observed within the sand and gravel aquifer at the site.  The high resolution possible with DTS enables this new method to provide a more detailed representation of aquifer flux than previous approaches.