Assessing groundwater quality and suitability for Agricultural use in Punjab, India: A spatial and temporal analysis.

Groundwater is a crucial global water resource; however, it faces the threat of depletion and quality degradation due to intensive agriculture and excessive fertilizer use. In India, groundwater assessments focus mainly on exploitation levels and often neglect quality. This study integrates groundwater quality with exploitation data to evaluate groundwater resources in Punjab, India. A novel Integrated Water Quality Index (IWQI), developed using advanced statistical techniques like Principal Component Analysis (PCA), identified Sodium (Na⁺), Sulphate (SO₄2⁻), Chlorine (Cl⁻), Sodium Adsorption Ratio (SAR), and Electrical Conductivity (EC) as key contributors to groundwater quality. Spatial-temporal maps for 2014 and 2022 classified water quality into five suitability classes: Excellent (0-35), Good (35-60), Poor (60-85), High Restrictions (85-100), and Severe Restrictions (> 100). Hydrogeochemical analyses, including Piper and Durov diagrams, indicated saline water dominance due to high fertilizer use. Notably, water quality degradation was observed in the North-Eastern, Western, and Southern regions, whereas the Central Punjab region, despite over-exploitation, retained excellent water quality for agricultural use. Statistical analysis revealed that 4.7% of the groundwater depth variability was linked to changes in water quality. The block-wise groundwater exploitation map from the Central Groundwater Board was refined to improve resource management and incorporate IWQI data, providing a more comprehensive view of Punjab's groundwater status. This study underscores the importance of integrating water quality into groundwater assessments to inform irrigation strategies and ensure sustainable water resource management.