Major ion chemistry and hydrochemical studies of groundwater of Bangalore South Taluk, India

Abstract

Groundwater is almost globally important for human consumption as well as for the support of habitat and for maintaining the quality of base flow to rivers, while its quality assessment is essential to ensure sustainable safe use of the resources for drinking, agricultural, and industrial purposes. In the current study, 28 groundwater samples were collected around Vrishabhavathi valley region of Bangalore South Taluk to assess water quality and investigate hydrochemical nature by analyzing the major cations (Ca^2 +, Mg^2 +, Na⁺, K⁺) and anions $(\text{HCO}_{3}^{-}$, Cl⁻, F⁻, $\text{SO}_{4}^{2-}$, $\text{NO}_{3}^{-}$, $\text{PO}_{4}^{3-}$, $\text{CO}_{3}^{2-})$ besides some physical and chemical parameters (pH, electrical conductivity, alkalinity, and total hardness). Also, geographic information system-based groundwater quality mapping in the form of visually communicating contour maps was developed to delineate spatial variation in physico-chemical characteristics of groundwater samples. Piper trilinear diagram was constructed to identify groundwater groups (hydrochemical facies) using major anionic and cationic concentration and it was found that majority of the samples belongs to $\text{Ca}^{2+}-\text{Mg}^{2+}-\text{Cl}^{-}-\text{SO}_{4}^{2-}$ and $\text{Ca}^{2+}-\text{Mg}^{2+}-\text{HCO}_{3}^{-}$ hydrochemical facies. Wilcox classification and US Salinity Laboratory hazard diagram suggests that 92.86% of the samples were falling under good to permissible category and C3–S1 groups, respectively, indicating high salinity/low sodium.