Evaluation of hydrogeochemical characteristics and groundwater quality in the quaternary aquifers of Unnao District, Uttar Pradesh, India

The present study has been carried out to assess the factors controlling the hydrogeochemical characteristics and groundwater quality in a part of Unnao district, Uttar Pradesh, India. For this purpose total 68 groundwater samples were collected from pre- and post- monsoon season corresponding to June and November 2013 and analyzed for physico-chemical parameters such as pH, electrical conductivity, total hardness, total dissolved solids and major cations (Ca2+, Mg2+, Na+, K+) and anions (HCO3−, Cl−, SO42−, NO3−, F−). Groundwater of the area is slightly alkaline in nature. Major groundwater facies identified are ‘Ca + Mg-HCO3’ and ‘Na + K-HCO3’ during both sampling seasons. The PHREEQC geochemical modeling program was used to evaluate the saturation state of minerals and its dissolution/precipitation reactions occurring in groundwater. The computed saturation indices demonstrate oversaturated condition with respect to dolomite and calcite and undersaturated condition with gypsum, halite and fluorite. Drinking and agriculture quality of groundwater samples were also assessed. Parameters such as total dissolved solids, Na+, K+, HCO3−, Cl−, SO42−, F− exceed the desirable limits of drinking water standards as prescribed by Bureau of Indian Standards and Word Health Organization in few samples. Agricultural water quality is assessed by using various indices such as sodium adsorption ratio, residual sodium carbonate, and permeability index. Excess value of these indices at some sites restrict its suitability for irrigation purpose. Therefore, groundwater management plan is required to improve the water quality in the area. Keywords: Groundwater, Hydrogeochemical characteristics, Saturation index, Water quality, Unnao, India