GIS and Geostatistical Techniques for Groundwater Science - Chapter 6 - Methods for Assessing the Groundwater Quality

The suitability of groundwater for drinking and irrigation purposes was evaluated using Water Quality Index, GIS and Multivariate Statistical method in a part of Nalgonda District, Telangana, India. Forty-five groundwater samples were collected from wells on January, 2010. On-site field measurements of pH, electrical conductivity (EC), and temperature, and the laboratory analysis of major ions were carried out. Six groundwater types are dominant: Ca-HCO3, Na-Cl, mixed Ca-Na-HCO3, mixed Ca-Mg-Cl, Ca-Cl, and Na-HCO3. Spatial variation maps were developed for physicochemical parameters by using inverse distance weighted interpolation method and grouping analysis. These maps are categorized as desirable, permissible, and not permissible according to the World Health Organization (WHO) standard. The water-quality index map comprised a 443 km2 area categorized as good for drinking purposes. Groundwater is suitable for irrigation by SAR, EC, Na%, PI, RSC, MR, and USSL classification and Wilcox methods. Multivariate statistical techniques of correlation matrix, factor analysis, and cluster analysis evaluated the hydrochemical variations and the driving factors as well as the hydrogeochemical characteristics of the aquifer. The final section of this study concludes that groundwater quality is mainly affected by water-rock interactions, intensive agricultural activities, and the anthropogenic activity in the study area.