Assessment of groundwater quality for drinking and irrigation purposes using hydrochemical studies in Nalbari district of Assam, India

The present work was carried out in Nalbari district of Assam (India) with an objective to assess the quality of groundwater and to check its suitability for drinking and irrigation purposes. Groundwater samples were collected from 50 different locations during pre- and post-monsoon seasons of 2016. Results of chemical analysis revealed that mean concentration of cations varied in the order Ca2+ > Na+ > Mg2+ > K+, while for anions the order was HCO3- > Cl- > SO42- > NO32- > F- during both pre- and post-monsoon seasons. The suitability of groundwater samples for drinking purpose was assessed by comparing the results of physico-chemical analysis of groundwater with Indian Standards. Further, its suitability for irrigation purpose was assessed by evaluating several parameters like sodium adsorption ratio (SAR), sodium percentage (Na%), magnesium ratio, Kelly's ratio and residual sodium carbonate (RSC). The SAR values obtained for all the samples were plotted against EC values in the US Salinity Laboratory diagram, and it was revealed that the most of the samples fall under water type C2-S1 indicating medium salinity and low SAR. Further, it was found that the majority of the samples belong to Ca-Mg-HCO3 hydrochemical facies followed by Ca-Mg-Cl-SO4, whereas only a few samples belong to Na-K-HCO3 hydrochemical facies.