Electrical Resistivity Tomography (ERT) Surveys on the Des Moines River Floodplain, Des Moines, Iowa, 2018

Electrical resistivity tomography (ERT) surveys were collected in summer 2018 to support hydrogeologic characterization of the alluvial aquifer. For this investigation, 7 surveys were conducted with ERT methods. At each site three surveys were collected, including dipole-dipole (DD), Wenner-Schlumberger (WS), and Inverse Schlumberger (SI )configurations. For each survey a total of 56 electrodes spaced 5-meters (m) apart were used. During the ERT measurement, current is injected through two current electrodes and voltage is measured sequentially across multiple pairs of potential electrodes, which is used to determine the apparent resistivity of the subsurface. Results were combined into a merged dataset. ERT surveys can be inverted to obtain resistivity profiles that can be interpreted for subsurface layers. This data release provides only the raw ERT data and the resultant inversion model. This data release contains a notes file for archiving surface-geophysical data (ERT_Archive_Notes_DesMoinesIA.csv), a text file (readme_ERT.txt) explaining the data files and processing references, and a color scale file (ERT_colorscale.png) relating colors to resistivity values. This data release also contains 7 compressed zip folders (one for each survey line) containing the original instrument files (windows command scripts, .crs, and .stg). There is a windows command script, a .crs, and a .stg file for each configuration: dipole-dipole (DD), Wenner-Schlumberger (WS), and Inverse Schlumberger (SI), two .xyz files (raw data culled and inverted data), and inverted model output image for each survey line (.wmf). Field notes taken at the time of data collection are not included in this data release but are available upon request.