Appraisal of groundwater susceptibility to pollution using hybrid framework of stable isotopes and indexed approach

This study presents an integrated framework for assessing groundwater contamination risks by combining intrinsic aquifer vulnerability, isotope hydrology, and geospatial pollutant loading indicators. A two-dimensional vulnerability mapping approach was developed using a modified GOD index and δ¹⁸O stable isotope tracer, enabling evaluation of both vertical and lateral contaminant transport within the aquifer system. Pollution sources and loading potential were identified through remote sensing, land use classification, and hydrochemical data interpretation. Groundwater samples revealed significant hydrochemical variability, influenced by anthropogenic activities, salinization, and geogenic processes. Principal Component Analysis (PCA) extracted five dominant components, geogenic, anthropogenic, salinity-driven, redox-related, and agricultural, explaining spatial and temporal patterns of groundwater quality deterioration. δ¹⁸O values ranged from 5.89 to  -8.62‰, indicating diverse recharge mechanisms and pollutant retardability, and offering insights into groundwater/surface water interactions and lateral migration risks. GOD index values ranged from 0.04 to 0.28, classifying the area predominantly within negligible to medium vulnerability zones. Clay-rich sectors exhibited high natural protectability, while industrial impacted zones showed increased susceptibility. A fuzzy logic-based correlation between GOD scores and isotopic interpretations enhanced aquifer vulnerability assessment, providing a spatially explicit and nuanced risk evaluation. This study integrates established tools to improve groundwater risk characterization. The proposed framework supports contamination threat anticipation, prioritization of high-risk zones, and site-specific protection strategies. It facilitates evidence-based land use planning, targeted monitoring, and adaptive management, contributing to the long-term sustainability of aquifer systems in environmentally complex and industrially stressed regions.