Study of groundwater hydrochemistry and drinking suitability through Water Quality Index (WQI) modelling in Kadava river basin, India

The present study aims to know the groundwater hydrochemistry and its drinking suitability in Kadava river basin through Water Quality Index (WQI) modelling approach. Eighty (80) dug/bore well samples were collected and analysed for the span of dry (pre) and wet (post) monsoon seasons of 2012 by following standard procedures of APHA. According to BIS standard, the parameters, viz., pH, Ca, Mg, Na, Cl, NO3, TH and TDS, surpass the threshold limits in both the seasons. It is observed that TDS content in pre- (75%) and post (97.5%)-monsoon seasons is exceeding the desirable limit (500 mg/l). Also, 67.5% (pre-monsoon) and 75% (post-monsoon) of the groundwater samples are beyond the nitrate permissible limit (45 mg/l) of the BIS. The magnesium content in 15 and 37.5% samples is surpassing the permissible limit (100 mg/l) in pre- and post-monsoon seasons. TH content in 15 and 25% samples surpassed the permissible limit (600 mg/l) in pre- and post-monsoon seasons. WQI results demonstrated that 50.0 and 22.5% samples come under good quality of water; 47.5 and 72.5% samples fall in poor water category, while 2.5 and 5.0% samples exhibit very poor category in pre-/post-monsoon seasons. Hydrochemical characterization based on Durov plot, Chaddha diagram, Gibbs plot and various scatter plots was used to ascertain the types of weathering, influence of rock, precipitation and evaporation, types of reactions, etc., influenced on groundwater composition of the region. The groundwater chemistry is mostly deteriorated due to the influence of agricultural and anthropogenic activities. Spatial variation map of WQI exhibits that groundwater quality is affected mainly in south and few patches in north regions of the study area.