Electrical tomography and 3D geophysical models towards informed land-use planning in glacial-fluvial outwash plain

We use two-dimensional electrical resistivity tomography (ERT) methods to delineate and model in three dimensions the localized nature and extent of Wisconsinan-age outwash deposits. The study area consisted of five adjacent sites, including agricultural fields, residential neighborhoods, and natural areas. Data were collected in spring of 2017 using an ABEM Terrameter 4000 and a dipole-dipole array. The data collected included twenty-four ERT profiles with a total nominal length of 16,305 meters (just over ten miles). At each site, a network of ERT profiles was collected. The spacing between most of the parallel profiles was approximately 100 meters, but a few of lines were spaced about 200 m apart. Most of the data collected had a depth of investigation of about 20 meters, but several profiles extended to 80 meters. These 2-D profiles were processed through inversion and the resulting data was interpolated in two-dimensions and three dimensions. The 2-D interpolations were only performed to the depth of the shallower lines-about 20 meters-to ensure sufficient data density. Figure 1 is an example of the twenty-four lines we obtained showing the stratifications we saw generally through all the sites: a somewhat resistive layer atop a highly resistive layer on top of a less resistive layer. This specific profile had a highly resistive layer that was among the thickest in the dataset.