A Hydrogeochemical Characterization and Quality Assessment of Groundwater from the Sadar Upazila, Khagrachhari District, Bangladesh for Irrigation and Drinking Uses

Water scarcity in the hill tract districts of Bangladesh becomes acute in the dry season as most of the streams, the primary source of water, dry up. However, groundwater, where available, can supply water throughout the year. In this study, a total of 37 water samples were collected and analyzed from shallow (34) and deep (3) wells in Khagrachhari Sadar to assess their geochemical type and suitability for drinking using a multiparameter groundwater quality index (GWQI), as well as their suitability for irrigation uses using the sodium adsorption ratio (SAR), residual sodium carbonate (RSC), sodium percentage (SP), and the Riverside and Wilcox classifications. The physicochemical parameters of the groundwater were characterized by relatively low EC, low pH, positive redox potentials (Eh) in millivolts, and mostly soft water. Shallow wells were dominated by Ca-HCO3- and Ca-Na-HCO3-type water, and deep wells by Na-HCO3-type water. Among major and trace ions, there were higher concentrations, exceeding safe water standards, of HCO3- in deep wells and NO3-, Fe2+, and Mn2+ in shallow wells. Irrigation water quality assessments and GWQI results reveal that most shallow wells can be considered good and safe options for both drinking and irrigation, while groundwater from deep wells requires additional caution prior to use for agricultural purposes.