Assessing groundwater integrity: Insights into non-point source pollution patterns in the Palar River basin

• Groundwater quality assessment: The Palar River Basin was evaluated for Non-Point Source pollution from industrial, agricultural, and urban sources. • Spatial variability: Analysis of 485 post-monsoon samples revealed significant spatial variability in groundwater quality. • Water Quality Index: Over 70% of samples exceeded drinking water standards. • Sustainable water management: Findings highlight the need for Nature-Based Solutions, aligning with SDGs 6, 11, 12, 13, and 15. Groundwater quality is a vital indicator of environmental health, particularly in areas affected by non-point source (NPS) pollution from agricultural, urban, and industrial activities. This study evaluated 485 post-monsoon groundwater samples from the Palar River basin in Vellore District, Tamil Nadu, using spatial analysis, multivariate statistics, and Water Quality Index (WQI) assessments to delineate pollution gradients and hotspots relative to the river. Results reveal significant spatial variability, with elevated contaminant levels near the river primarily driven by industrial effluents, agricultural runoff, and urban waste. Principal Component and Correlation Analyses underscored the complex interactions among key pollutants, while the WQI indicated that over 70% of samples exceed safe drinking limits. GIS mapping further identified contamination hotspots, guiding targeted management interventions. Incorporating Nature-Based Solutions (NBS), such as wetland restoration and riparian buffers, is recommended to enhance natural filtration and aquifer recharge. Aligned with SDGs 6, 11, 12, 13 and 15, these findings establish a robust baseline for informed regional water resource management and policy development aimed at mitigating NPS pollution and promoting sustainable groundwater quality.