Spatio-temporal characterization of groundwater hydrogeochemistry using GIS, multivariate statistics and geochemical modeling in the Lower Ganga-Yamuna Doab region, India
Ashutosh Mishra, Prabuddh Kumar Mishra, Anupam Mishra, H. K. Pandey, Kamal Abdelrahman, Mohammed S. Fnais
Abstract
Groundwater is essential to sustain life but is susceptible to geogenic and anthropogenic contamination. This study investigates hydrochemical characteristics, contamination sources and geochemical mechanisms affecting groundwater mineralization in India’s Lower Ganga-Yamuna Doab region. Under investigation, a total of 314 groundwater samples were collected during the pre-monsoon (PrM) and post-monsoon (PoM) seasons and analyzed for 15 physico-chemical parameters. The findings reveal that the groundwater in the study area is predominantly fresh but hard, with higher concentrations of fluoride, nitrate, and iron. Major cations and anions were found in the order of Na + > Ca 2+ > Mg 2+ > K + > Fe 2+ and HCO 3 − > Cl − > SO 4 2− > NO 3 − > F − . The Piper diagram reveals that the prevailing hydrochemical facies were mixed Ca–Na–HCO 3 and Ca–HCO 3 . The chloro-alkaline indices (CIA) and the Chadha diagram suggest that both ion exchange and reverse ion exchange processes have influenced the hydrochemistry of groundwater. The spatial variation of groundwater hydrochemistry can be attributed to the higher concentrations of TDS, TH, HCO 3 − , F − , NO 3 − , and Fe 2+ . However, the temporal variation in the groundwater geochemistry was controlled by the dilution effect of rainwater. A multivariate analysis employing principal component analysis and the Pearson correlation matrix provides a robust framework for understanding the complex interactions affecting groundwater quality. Gibbs diagram and geochemical modeling revealed that the primary influences on major ion chemistry in both the period are weathering and dissolution of carbonate and silicate minerals and the interactions between rock and water. However, during the PoM period, variations in hydrogeochemical behavior are likely caused by factors such as rainfall-induced irrigation return flow, leaching of fertilizers and other anthropogenic inputs. This study employs an interdisciplinary approach, offering significant insights for developing sustainable groundwater management strategies in the region.