Integrated approach for the investigation of groundwater quality through hydrochemistry and water quality index (WQI)

Evaluation of groundwater quality and their controlling processes are very important for the sustainable utilization of groundwater in any region. In the present study, 100 groundwater samples were collected during pre-monsoon and post-monsoon 2019 from the tube well and public water supply wells in Mewat district, Haryana to investigate the water quality for drinking purposes and their controlling hydrogeochemical processes through an integrated approach. Different methods like conventional hydrogeochemical analysis, ion ratio plots, and water quality index (WQI) were applied. The results showed that the groundwater of Mewat is highly saline, with the average concentration of total dissolved solids (TDS) during the pre-monsoon (PRM) and post-monsoon (POM) being 4435 mg/L and 4938 mg/L, respectively. Statistical results revealed that anion concentrations follow the order as Cl- > SO42- > HCO3- > NO3- while cation con-centrations were Na+ > Ca2+ > Mg2+ > K+. The dominant hydrochemical types of Mewat groundwater were identified to be Ca2+.Mg2+- SO42- .Cl- and SO42- .Cl-- Na+. Silicate weathering, evaporation, and cation exchange were the three factors that control the composition of groundwater of Mewat. The chloro-Alkali indices indicate the dominance of direct base cation exchange reaction in the study area. Moreover, the results of the water quality evaluation showed that the values of WQI ranged from 72 to 3683 and 51 to 2451 during PRM and POM, respec-tively. WQI classes, namely Very poor and Poor water for drinking, are cumulatively represented by 64% and 58% of the total samples over the PRM and POM. And groundwater of Mewat was found mostly not suitable for drinking purposes. This is the first work in the Mewat district to assess the groundwater quality using WQI and their controlling hydrogeochemical process. This study provides insight into fundamental processes and aquifer controlling factors that are sig-nificant for the sustainable management of Mewat groundwater resources.