| Cross Borehole Ground Penetrating Radar (XBGPR) is used in monitoring a series of vadose zone infiltration experiments at a test site in Socorro, New Mexico in order to examine contaminant transport in the vadose zone. A water-infiltration and two-stage salt infiltration experiment were conducted at this site in order to investigate flow and solute transport mechanisms in the vadose zone. This research focuses on testing the application and analyzing the resolution of the XBGPR tomography technique in monitoring vadose zone flow and solute transport. The results show that XBGPR tomograms are able to provide high-resolution images that indicate regions of higher water content and locations of fine-grained materials. However, artifacts arising from the inversion processes are also present in the attenuation images. These artifacts are caused by the use of straight-ray inversion to approximate curved-ray, near-field propagation of the EM waves. Thus, it is necessary to properly incorporate physics into the inversion algorithms in order to correctly invert for the attenuation. |
