Identification of the processes controlling groundwater quality in shallow aquifers of Moradabad city, west Uttar Pradesh, India

Abstract

Present study has been carried out to identify the processes controlling groundwater quality of Moradabad city, Uttar Pradesh. A total 188 groundwater samples were collected and analyzed for major ions in pre- and post-monsoon seasons of years 2012 and 2013. Analysis results showed higher concentration of Na, K, Cl, SO4 and NO3. LL diagram showed dominance of alkalis and Cl + SO4, in three sampling seasons except in post-monsoon 2012, when Na + K–Cl + SO4 facies is recorded in 50% samples. There is dearth of HCO3 complexes in the pre-monsoon season of 2012, and then, their appearance in the post-monsoon season with alkali bicarbonates being 50%. This trend is reversed in 2013. Groundwater composition showed potential impact of varying rainfall pattern suggesting that chemistry of groundwater is intimately related to meteorological parameters. To predict minerals and their reactivity in groundwater, saturation index (SI) was calculated for pre- and post-monsoon of 2012. Groundwater is highly under-saturated with respect to halite, sulphates of Ca and fluorite and super-saturated with respect to chalcedony, quartz and talc, and these minerals may possibly be precipitated out. Relationship of SiO2 with Cl and TDS gives unequivocal evidence of anthropogenic factors having significant effect in determining the chemical characteristics of groundwater. Groundwater chemistry of the area is sum total of factors, such as, meteorological, hydrological and lithological and a set of processes related to various domains of anthropogenic activities, where variation in intensity and distribution of rainfall seems to be one of the driving factors responsible for overall temporal variations in groundwater chemistry.