Spatio-temporal variations in groundwater quality in the parts of South-western Punjab, India

Abstract

Spatio-temporal variations in groundwater quality for drinking and irrigation purposes were assessed in the parts of Bathinda district in Punjab (India). A total of 800 geotagged water samples (400 samples in each season) were collected from running tubewells during pre-monsoon (June 2020) and post-monsoon (October 2020) seasons. These water samples were analyzed for pH, electrical conductivity (EC), major cations (Ca2+, Mg2+, Na+ and K+) and anions (CO32−, HCO3−, Cl−, SO42− and NO3−) using standard methods. The water samples were categorized into drinking and irrigation purposes based on water quality index (WQI). Results showed that electrical conductivity, total dissolved solids, total hardness (including Ca2+, Mg2+), Cl−, and NO3− concentration in groundwater samples were significantly (p < 0.05) higher during post-monsoon than pre-monsoon season. Total alkalinity (including CO32− and HCO3− concentration in groundwater), pH, Na+, K+ and SO42− concentration in groundwater was significantly (p < 0.05) higher during pre-monsoon than post-monsoon season. The water quality for drinking purposes deteriorated from pre- to post-monsoon season, but water quality for irrigation purposes improved from pre- to post-monsoon season. The Gibbs diagram showed that direct and reverse exchange reactions occurred in groundwater samples. Spatio-temporal variations in groundwater based on various indices and WQI showed the specific locations for water management. Multivariate analysis showed that three diverse sets of constraints (salinity, carbonates hardness, and pollution processes) influence the groundwater chemistry of the study area.