An appraisal of groundwater quality for drinking and irrigation purposes in southern part of Bathinda district of Punjab, northwest India

Groundwater is being used for drinking and irrigation purposes in the agricultural dominated Indian state of Punjab. Fifty-six groundwater samples were collected from Bathinda, a south-western district of Punjab, during the pre-monsoon (March 2010) and post-monsoon (October 2011) seasons. These samples were tested for major cations, anions and contaminants. Various classification systems were used to study the groundwater quality with respect to drinking as well as irrigation purposes. Total dissolved solids (TDS) and total hardness (TH) are generally used to determine the suitability of groundwater for drinking purpose. Considering TDS as a parameter, 54 and 57 % groundwater samples were found to be unsuitable for use during the pre- and post-monsoon seasons. A wide range of TH values were observed in the pre-monsoon and post-monsoon waters samples (mean 250 and 270 mgL⁻¹). About 75 % of pre-monsoon and 79 % of post-monsoon samples exceeded the maximum permissible limit (MPL) of TH (150 mg L⁻¹) proposed by WHO. In terms of contaminant ions, 40 % and 55 % of the pre- and post-monsoon water samples were unfit for drinking purposes w.r.t. fluoride (MPL 1.5 mg F L⁻¹), 29 and 36 % were unfit w.r.t arsenic (MPL 10 μg L⁻¹) and 33 and 45 % were unfit w.r.t nitrate (MPL 45 mg NO₃ ⁻ L⁻¹), respectively. To determine the suitability of groundwater of Bathinda for irrigation purpose, three classification systems proposed by different research workers were used. The parameters electrical conductivity (EC), sodium adsorption ratio, and residual sodium carbonate (RSC) were calculated on the basis of chemical data. Considering EC and RSC together, 32 % samples collected during pre-monsoon season were fit, 19 % were marginal and 49 % were unfit for use. However, during post-monsoon, samples fit for irrigation decreased to 17 % and samples unfit for irrigation increased to 70 %. Increases in the percentage of unfit samples for irrigation after monsoon indicates addition of salts along with the rain water percolated into the groundwater. The other two classification systems, i.e. US Salinity diagram and Wilcox diagram also showed the similar results.