Statistical approaches for hydrogeochemical characterization of groundwater in West Delhi, India

Abstract

Parametric statistical approaches, correlations and multiple linear regressions were used to develop models for the interpretation of hydrogeochemical parameters in the Western part of Delhi sate, India. The hydrogeochemical parameters indicated that the groundwater quality is not safe for consumption. The water is moderately saline and the salinity level is increasing over time. There is also the problem of nitrate pollution. The correlation between electrical conductivity (EC) and other water quality parameters except potassium (K⁺), nitrate (NO₃ ⁻) and bicarbonate (HCO₃ ⁻) is significantly positive and Ca⁺⁺ + Mg⁺⁺/Na⁺ + K⁺ is significantly negative. In predicting EC, the multiple R² values of 0.996 and 0.985 indicate that 99.6% and 98.5% variability in the observed EC could be ascribed to the combined effect of Na⁺, HCO₃ ⁻, Cl⁻, SO₄ ⁻⁻, NO₃ ⁻ and Ca⁺⁺ + Mg⁺⁺ for the year of 2005 and 2006 respectively. Out of 99.6% of the variability in EC in 2005, 51.2% was due to Cl⁻ alone, and 8.5%, 12.5%, 6.1%, 14.7% and 6.7% were due to Na⁺, HCO₃ ⁻, SO₄ ⁻⁻, NO₃ ⁻ and Ca⁺⁺ + Mg⁺⁺. Similarly in 2006, out of 98.5% of the variability in EC, 48.5% was due to Cl⁻ alone, and 10.4%, 12.7%, 5.3%, 17.2% and 4.4% were due to Na⁺, HCO₃ ⁻, SO₄ ⁻⁻, NO₃ ⁻ and Ca⁺⁺ + Mg⁺⁺. The analysis shows that a good correlation exists between EC, Cl⁻ and SO₄ ⁻⁻ either individually or in combination with other ions and the multiple regression models can predict EC at 5% level of significance.