Integration of geo-electrostratigraphic data and hydrogeological parameters in SINTACS, AVI, and GOD vulnerability models for enhanced groundwater vulnerability assessment

ABSTRACT Graphical abstract showing aquifer vulnerability using resistivity data, 2D tomograms, and vulnerability indices (GOD, SINTACS), with high- and low-risk zones. Groundwater vulnerability assessments are crucial for sustainable water resource management, especially in regions experiencing anthropogenic pressures. This study integrated geo-electrostratigraphic data with SINTACS, aquifer vulnerability index (AVI), and Groundwater occurrence – Overlying lithology – Depth (GOD) models to enhance vulnerability mapping within a major coastal aquifer impacted by saline intrusion. SINTACS incorporates depth of groundwater (S), infiltration (I), nature of vadose zone (N), type of soil (T), aquifer media (A), hydraulic conductivity (C), and slope/topography (S). The AVI evaluates aquifer susceptibility based on hydraulic resistance, while the GOD model is derived from groundwater occurrence, overlying lithology, and depth to groundwater. This hybrid, multimodel assessment approach was necessary to reduce model-specific bias, improve spatial reliability, and increase confidence in the results. SINTACS scores (154–188) classified 90% of the area as having moderate-high vulnerability, and 10% as having high vulnerability to contamination. This was corroborated by GOD scores (0.35–0.63) and AVI scores (1.23–2.59), with the most vulnerable zones concentrated in areas with thin overburden. Longitudinal conductance was used to corroborate results obtained from the vulnerability models. This work provides a scientifically robust framework for assessing aquifer vulnerability within heterogeneous aquifer systems, and the methodologies employed are replicable in other regions worldwide.