Estimating suitability of groundwater for drinking and irrigation, in Odisha (India) by statistical and WQI methods

Twelve major hydro-geochemical parameters derived from about 1134 water samples were studied to understand spatial variation of groundwater quality in the coastal state of Odisha. Multivariate statistical analysis techniques, i.e., cluster analysis and principal component analysis (PCA), and varimax rotation were used to classify various types of groundwater, and plausible sources that control the quality of water in the region. The concentration of major ions varies in the order of Na⁺ > Ca²⁺ > Mg²⁺ > K⁺ and HCO₃^- > Cl^- > SO₄^2- > F^-. Out of the three clusters identified, the 2nd cluster is having more mineralization and relatively poor quality of groundwater as compared to the first and the third cluster. Furthermore, estimates of the Water Quality Index (WQI) indicate that the groundwater in the area can be classified from excellent to medium quality. Furthermore, the sodium absorption ratio (SAR) and Kelly's ratio (KR) suggest that about 70% of groundwater samples are of low to medium salinity, whereas about 30% show higher salinity. The Wilcox diagram reveals that almost 90% of the groundwater is suitable for irrigation. The mining activity appears less likely to be affecting the quality of subsurface water. Water-rock interactions and evaporation-crystallization may be the two dominant factors that appear to control the groundwater away from the coastal areas. Results of this study may be useful to identify the suitable sites for groundwater extraction for drinking and irrigation purposes, besides being useful to the policy-makers in formulating effective plans for preventing further contamination of groundwater aquifers.