Improving ERT Imaging of Small-Size 2D Targets Using Different Strategies

Investigation of small-size two-dimensional (2D) targets is a difficult task; it requires—among others—arrays with a high horizontal resolution. According to numerical calculations and quasi-field studies besides the Dipole, the γ 11n arrays, a special group of quasi null arrays were expected to be appropriate for this aim. Test field measurements were carried out by these arrays and the Wenner array to study small-size targets, as trenches and leakages linked to pipes whose parameters are known. These are the first field measurements performed with γ11 arrays, or even with any quasi-null arrays. For the investigation of small objects using just one array, the γ 114 -, γ 112 -, and dipole arrays proved to be the best. The effect of three principal strategies and five of their possible combinations are also demonstrated. Each of them could improve the performance of the electrical resistivity tomography (ERT), e.g. by separating 2D and 3D effects or true anomalies and artefacts, and increasing the reliability of the results. The strategy which may provide the most accurate results, the economically most advantageous method and a profit/investment optimized array set to solve problems of small 2D targets are presented. Each strategy is also suitable using solely traditional arrays, but the results may be better when γ 11n arrays are also involved. In the study site, each known small target could be detected. The presented strategies are recommended to apply when small 2D targets thus, e.g. pipes, trenches, tunnels, mining cuts, long straight caves, archaeological ruins (walls, basements), fractures, or dykes are studied.