Identification of underground water-bearing caves in noisy urban environments (Wuhan, China) using 3D electrical resistivity tomography techniques

Caves formed in hard limestone due to groundwater erosion and rainwater infiltration may cause damages of buildings. The electrical resistivity tomography (ERT) with high lateral resolution and low economic cost is a good way to detect the caves, as the electrical resistivity of water-bearing caves is much lower than that of surrounding rocks. In this study, we arranged three sets of intersected ERT profiles to detect the unknown water-bearing caves in an area of Wuhan city of China. Both two-dimensional and three-dimensional inversions were performed to obtain the underground electrical resistivity tomography images. The reliability of imaged water-bearing caves was analyzed in terms of the reliability analysis tool. The inversion results not only agree well with the drilling results, but also detect five possible locations of water-bearing caves in the limestone bedrock. The findings of these underground water-bearing caves in advance can effectively avoid potential safety hazards as this area will become the commercial center of Wuhan city. •29 intersected ERT lines with 2663 electrodes were arranged.•Both the depth of investigation index tool and drilling verification were adopted to increase the ERT reliability.•Five new water-bearing caves were found with high confidence levels.