Assessing Impacts of Mining-Induced Land Use Changes on Groundwater and Surface Water Quality Using Isotopic and Hydrogeochemical Signatures

The current investigation aimed to assess the impact of land use changes on groundwater quality because of the extensive mining activities in the coal mining province of the Mahan River catchment area, which is located in the Surguja district of Chhattisgarh, India. The water quality index (WQI), Collin’s ratio, stable isotope ratios of water molecules (δ 18 O and δD), and various physicochemical parameters were measured to determine the suitability of water for domestic purposes. Water samples collected from dug wells, tube wells, river water, and mine water were analyzed, and the results revealed that 28% of the samples were classified as excellent and 44%were classified as good during the pre-monsoon period. In the post-monsoon period, 50% of the samples were categorized as good, while 35% were classified as poor, whereas in mining areas, 54% of samples were found to be unsuitable during the pre-monsoon period, and this increased to 77% in the post-monsoon period. Stable isotope analysis was also conducted: samples were plotted to the right of the Local Meteoric Water Line (LMWL) in the isotope bivariate plot, and the observed slopes for all samples were smaller than that of the LMWL. The enrichment of the δ 18 O ratio and negative d-excess values at certain locations suggest the occurrence of non-equilibrium processes and mixing mechanisms.