Type-curve analysis of water-level changes induced by a longwall mine

Subsidence due to longwall mining creates long-term environmental effects, such as alteration of surface drainage patterns, changes in aquifer charact eristics, and water-level drops in wells near the mine panel. Evaluating th e impact of longwall mining on groundwater resources requires a knowledge o f aquifer properties, both in front of, and behind, the mining face. In thi s study, we develop a a method based on the one-dimensional flow equation, and utilize type-curves to estimate an aquifer hydraulic diffusivity value from water level versus time measurements at a single well. We tested the m ethod by calculating the hydraulic diffusivity value of the Trivoli Sandsto ne aquifer over a long-wall coal mine in the Illinois Basin, and our result s reasonably close to reported values. The presented method significantly r educes the computational effort involved in: (1) predicting mine-induced wa ter-level drops, and (2) determining the hydraulic conductivity and storage coefficient value representative of a larger aquifer volume, as compared t o conventional aquifer test methods.