Identification of preferential flow paths by hydraulic tomography compared with tracer test and the groundwater contour map in coal mine water hazard area

Water inrush accident in the mining area is a potential hazard in the coal mining industry. Detailed detection of the inrush flow paths remains a challenge for the industry. In this study, taking the Panbei coal mine as an example, a new strategy of hydraulic tomography (HT) inversion is proposed. In order to improve the accuracy of inversion, the geological information of the site is brought into the HT inversion as a boundary condition. Then, we analyze the effect of different inversion sequences and prior information on the inversion results of HT. Finally, we use the results of HT compared with tracer test results and groundwater level contour map to determine the preferential flow paths of the study area. The results showed that: (1) The inversion sequence will not significantly impact the HT results because the distribution of K and S.S. obtained by inversion does not have a significant deviation. (2) The sequential inversion with prior information has higher accuracy than the traditional continuous inversion. HT an identify the location of fault zones. (3) Combined with the tracer test results, it can be determined that the DF1 (fault zone) has strong conductivity, while the F70 (fault zone) and WF1 (fault zone) are weakly permeable. Then, combined with the contour map of the groundwater level, it can be inferred that the preferential flow paths of groundwater in the study area. From the C3I formation outcrop, water was supplied by the Panji anticline. Groundwater mainly flows from northwest to southeast; most groundwater flow paths are along the development direction of the fault zone. The results of this paper verify that HT is a promising technology for exploring the groundwater preferential flow paths in the coal mine area.