Evaluation of hydrogeochemistry and water quality in Bist-Doab region, Punjab, India

Agricultural activities act as dominant polluter of groundwater due to increased fertilizers and pesticides usage. Bist-Doab region, Punjab, India, is one such region facing deterioration of groundwater quality due to usage of fertilizers. This study aims in delineating and evaluating the groundwater quality in the region. Water samples are collected from canals, reservoir, and shallow and deep groundwater. Water types in canal and reservoir in Kandi region are Mg²⁺HCO₃ ⁻ and Mg²⁺Ca²⁺Na⁺HCO₃ ⁻, respectively. While water types of shallow and deep groundwaters are found to be of two types: Na⁺Mg²⁺Ca²⁺HCO₃ ⁻ and Ca²⁺Mg²⁺Na⁺HCO₃ ⁻. Presence of Mg²⁺ in groundwater at locations adjoining canals indicates recharge due to canal. The major ion (Na⁺, Mg²⁺, Ca²⁺, HCO₃ ⁻) chemistry of the region is due to weathering of rocks that are rich in sodic minerals and kankar. Deep groundwater quality in the region meets BIS and WHO standards for drinking purpose, unlike shallow groundwater which is of poor quality at many locations. Both shallow and deep groundwater with high sodium concentration (>1.5 meq/l) affect cropping yield and permeability of soil matrix. High concentration of SO₄ ²⁻ and NO₃ ²⁻ (>1 meq/l) in shallow groundwater at few locations indicates influence of anthropogenic (fertilizer) activity. Factor analysis indicates that the major cations, bicarbonate and chloride are derived from weathering/dissolution of source rocks. Higher concentration of nitrate and presence of sulphate in shallow groundwater at few locations is due to usage of fertilizers and pesticides.