Groundwater Quality assessment using Water Quality Index (WQI) in parts of Varanasi District, Uttar Pradesh, India

The water quality index (WQI) is an important tool to determine the drinking water quality in urban, rural and industrial area. WQI is defined as an index reflecting the composite influence of different water quality parameters which is considered and taken for calculation of water quality index. In the present study, sixteen groundwater samples were collected from the southern portion of the Varanasi district, Uttar Pradesh, India, during the pre monsoon period of May, 2015. The twenty two water quality parameters have been considered for the calculation of water quality index viz. pH, electrical conductivity (EC), total hardness (TH), total dissolved solid (TDS), alkalinity, sodium (Na + ), potassium (K + ), calcium (Ca 2+ ), magnesium (Mg 2+ ), nitrates (NO 3" ), bicarbonate (HCO 3 – ), chlorides (Cl – ), sulphates (SO 4 – ), fluorides (F – ), chromium (Cr), zinc (Zn), copper (Cu), manganese (Mn), iron (Fe), nickel (Ni), lead (Pb) and cadmium (Cd). The Bureau of Indian Standard (BIS, 2012) has been considered to assess the suitability of groundwater for drinking purposes and for the calculation of WQI. Correlation study between various physicochemical properties also reveals significant negative relationships. The current study shows that ~20% area is falling under the non suitable for drinking water category and rest is falling under good, moderate, poor, very poor as per the WQI classification. The present study is helpful in proper planning and management of available water resource for drinking purpose.