TWO-DIMENSIONAL QUANTIFICATION OF GROUNDWATER FLUX USING HEAT AS A GROUNDWATER TRACER: APPLYING AMPLITUDE SHIFT METHODS TO DISTRIBUTED TEMPERATURE MEASUREMENTS

Current methods of using heat as a tracer to quantify groundwater discharge have been confined to 1D point measurements. While 2D measurement techniques using instruments such as Distributed Temperature Sensors (DTS) and remote sensing exist, these spatially distributed measurements have been limited primarily to qualitative results. Combining methods of a 1D quantitative approach with those of the 2D qualitative approach will provide a synoptic temperature profile of the stream bed allowing researchers to locate and quantify spatially variable points of diffuse flow. The work presented here evaluated the use of amplitude shifts in temperature signals at two depths along a simulated stream bed collected using a DTS to spatially quantify groundwater discharge. To accomplish this shift to 2D we have constructed both computer models and physical models. Our computer model simulating groundwater flow and heat transport was built in COMSOL Multiphysics. The initial computer model was able to evaluate numerous discharge scenarios before creating these scenarios in a controlled laboratory experiment. By controlling the discharge scenario in the computer model and laboratory experiments we are able to access the accuracy and resolution of using the DTS cable to quantitatively measure specific discharge.