Assessment of hydrological condition in strata associated with old mine working during and post-monsoon using electrical resistivity tomography: a case study

Water management is a strategic factor in old coal mine working areas due to disturbance in the aquifer caused by subsidence resulting in drying of wells and streams. Cavity formation due to underground mining leads to roof fall, heaving of clay floors and collapse of coal pillars in soft clay floors. Logging of water in old mine workings is a common phenomenon especially during rainy season. Mine water is extensively used in various mining activities, and hence, a study has been conducted in part of Jamadoba 6 and 7 Pits, Jharia coalfield, India, to assess the hydrological condition during and post-monsoon. Initially, a conceptual model has been prepared to identify the possible sources of water including its path entering into old mine workings. Electrical resistivity tomography (ERT) i.e. Wenner-Schlumberger configuration with quality factor 5 has been adopted as it is effectual and reliable in detecting subsurface cavities at shallow depth and the possible path of transmission of subsurface water into the mine void with season variation. The study helped in identification of abandoned incline, porous and permeable strata conditions. The correlation of the resistivity variations is observed to be in close approximation with working plans and available borehole lithology. This technique proved to be suitable for adopting such studies.