Hydrochemical Appraisal of Groundwater Quality for Managed Aquifer Recharge (MAR) in 1 Southern Punjab, Pakistan

Water quality assessment is crucial for the sustainable use and management of groundwater resources. This study was 5 carried out in the irrigated plains of Vehari District, Punjab, Pakistan, to evaluate groundwater suitability for a 6 managed aquifer recharge (MAR) project. Twenty-three groundwater samples were collected in June 2021 from an 7 area of 1,522 km² and analyzed for major physicochemical parameters including electrical conductivity (EC), total 8 dissolved solids (TDS), pH, turbidity, calcium (Ca), magnesium (Mg), chloride (Cl), alkalinity (Alk), bicarbonate 9 (HCO₃⁻), hardness, potassium (K), sulphate (SO₄²⁻), sodium (Na), and nitrate (NO₃⁻). Water quality was assessed 10 using WHO and PID standards, alongside derived hydrochemical indices such as sodium percentage (%Na), Kelley’s 11 ratio (KR), sodium adsorption ratio (SAR), residual sodium carbonate (RSC), and the water quality index (WQI). The 12 datasets were interpreted using geo-statistical, geospatial, multivariate, and correlation analyses. Cation and anion 13 dominance followed the order Na⁺ > Ca²⁺ > Mg²⁺ > K⁺ and HCO₃⁻ > SO₄²⁻ > Cl⁻ > NO₃⁻. WQI results showed that 14 35% of samples indicate “poor,” 50% “very poor,” and 15% “unsuitable” drinking-water quality. However, the irrigation 15 suitability indices confirmed that groundwater is generally acceptable for agricultural use, though unfit for drinking. 16 The outcomes of this study provide essential insights for groundwater management in the region, where the Punjab 17 Irrigation Department (PID) has initiated a MAR project. Considering that the irrigation sector is the major 18 groundwater consumer in the area, the compatibility of groundwater and surface water quality supports the 19 implementation of MAR to enhance agricultural sustainability.