Hydrogeochemical assessment of groundwater quality for drinking and irrigation purposes in western Coimbatore, South India

Abstract

Groundwater is the only freshwater in the region, as textile industry effluents pollute the Noyyal river. Therefore, a hydrogeochemical investigation was conducted in the western Coimbatore district of Tamil Nadu to examine the groundwater chemistry and its appropriateness for drinking and irrigation. For this purpose, 25 groundwater samples from a borewell were obtained in precleaned 1-L polythene bottles within the study area. The study found that almost all the analysed groundwater samples contained total hardness (TH), total dissolved solids (TDS), sodium (Na+\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${\\text{Na}}^{ + }$$\\end{document}), potassium (K+\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${\\text{K}}^{ + }$$\\end{document}), calcium Ca2+\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\left( {{\\text{Ca}}^{2 + } } \\right)$$\\end{document}, bicarbonate HCO3-\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${ }\\left( {{\\text{HCO}}_{3}^{ - } } \\right)$$\\end{document}, and chloride (Cl-\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${\\text{Cl}}^{ - }$$\\end{document}) above the World Health Organization and the Bureau of Indian Standards recommendations for drinking water. In the investigated area, the groundwater chemistry is predominantly of Ca2+-HCO3-\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${\\text{Ca}}^{2 + } - {\\rm{HCO}}_{3}^{ - }$$\\end{document} type, as shown in the Piper Trilinear diagram. Gibbs plot shows that groundwater chemistry is controlled by rock–water interaction. A geographic information system (GIS) platform was used to create a spatial distribution map of all the physical and chemical parameters. About 60% of the groundwater sample fall in the poor water class according to the Water Quality Index (WQI) assessment. In contrast, most groundwater samples are found suitable for irrigation purposes by computing sodium percentage, sodium adsorption ratio, salinity hazard, Kelly ratio, residual sodium carbonate and permeability index. These hydrogeochemical results could benefit stakeholders and farmers by managing the water resources in the study area.