Detection of water-rich areas and seepage channels via the transient electromagnetic method, electrical resistivity tomography, and self-potential method.

Groundwater serves as a vital water resource for human society, yet it also plays a significant role in geological- and engineering-related hazards, such as landslides, tunnel collapses, and mining-related issues. Detecting water-rich zones and groundwater seepage pathways is essential for mitigating these risks. The Xiaogangou Coal Mine, located in a low- to mid-mountainous region at the northern foot of the Tianshan Mountains in Xinjiang, China, contains multiple coal seams distributed at a depth of approximately 600 m. Surface infiltration from two rivers in the area has resulted in water-rich zones within the medium to coarse sandstone layers between these coal seams, posing a potential threat to mining operations and construction activities. In this study, geophysical methods, including transient electromagnetic surveys, electrical resistivity tomography, and self-potential measurements, were employed to investigate the extent of these water-rich zones and identify primary infiltration pathways. The transient electromagnetic data facilitated the construction of a three-dimensional geoelectric model of the mine, from which the planar distribution of resistivity in the medium to coarse sandstone layers-likely reservoirs of groundwater-was derived. Combining low-resistivity anomaly zones with geological and drilling data allowed for the delineation of water-rich areas. Additionally, two self-potential profiles along the rivers were used to map surface electric potential distributions, which, in conjunction with two-dimensional resistivity data from overlapping electrical resistivity tomography profiles, revealed the main infiltration points and seepage channels. The results from the three geophysical techniques corroborated one another, delineating the extent of the aquifer and demonstrating that the rivers recharge the groundwater through rock weathering and structural fractures. The subsequent post-processing of these detection results facilitated the construction of a comprehensive three-dimensional model of the groundwater system. This study highlights the efficacy of geoelectric methods in detecting water-rich zones and infiltration pathways in complex hydrogeological settings.