Assessment of Groundwater Quality Under Unplanned Urban Environment: a Case Study From Vellore City, Tamilnadu, India

Urban land cover changes impose multiple sources of contamination that severely degrade groundwater quality. The present study evaluates the seasonal assessment of groundwater quality in the unplanned urbanized city of Vellore, Tamil Nadu, India using hydrogeochemical analysis, multivariate statistical analysis and LULC map using GIS techniques. A total number of 96 groundwater samples were collected and analyzed in the year 2022. The Piper diagram shows that groundwater is dominated by Mixed Ca-Na-HCO₃, Mixed Ca–Mg–Cl and Na-Cl-SO₄, water types. Exceedances of BIS limits were observed for parameters such as Ca, Mg, K, Cl, NO₃, F and Coliforms during all the seasons in most of the samples. Principal component analysis (PCA) divides the water quality parameters into strong and moderate loading. Q mode of Hierarchical Cluster Analysis (HCA) reveals three clusters: residential, commercial and mixed zones, whereas R modes exhibited dominant parameters such as NO₃, Cl, TDS, Mg, F and Na. Both, high loading in PCA and the samples of Q mode and R mode exceeding the BIS-2012, limits clearly indicates that, the groundwater of this region is highly affected by the indicators of significant urban and geogenic influence. Further, the overlay analysis of Land Use and Land Cover map and groundwater samples, shows clear evident that the indicators present in the groundwater is corresponding to the urban activities of the study area. Therefore, this comprehensive study in Vellore, Tamil Nadu, will shed light on the sources of contaminants affecting groundwater quality and how they change with the seasons through the use of an integrated approach.