Abstract
<title>Abstract</title> <p>Groundwater is a critical resource in the arid Imiter region of the central Anti-Atlas, Morocco, where surface water is scarce, and groundwater occurrence is mainly controlled by fracture-related secondary permeability, terrain conditions, and hydrothermal alteration. This study delineates groundwater potential zones (GWPZs) by integrating multisource remote sensing, morphostructural analysis, terrain-derived indices, and airborne radiometric data within a GIS-based multi-criteria decision analysis (MCDA) framework. Eight thematic factors were considered: lineament density, topographic wetness index (TWI), slope, drainage density, normalized difference vegetation index (NDVI), and three ASTER-derived hydrothermal alteration indicators, namely carbonate, kaolinite, and Fe³ alteration. Slope, TWI, and drainage density were derived from SRTM-based terrain analysis, NDVI was calculated from Sentinel-2 imagery, lineament density was extracted from morphostructural analysis, and hydrothermal alteration layers were obtained from ASTER VNIR–SWIR data. The reclassified thematic layers were integrated using weighted overlay analysis, with lineament density assigned the strongest influence, followed by TWI, slope, drainage density, carbonate alteration, kaolinite alteration, NDVI, and Fe³ alteration. The resulting GWPZ map reveals strong structural and morphometric controls on groundwater favorability, with high-potential zones preferentially concentrated along fractured corridors and hydrothermally altered domains, where terrain conditions favor infiltration and subsurface accumulation. To evaluate the model independently, single-band airborne radiometric layers of uranium, thorium, and potassium were used to calculate U/Th and Th/K ratios, which were then compared with the predicted GWPZ classes through point-based validation. A total of 5307 validation points were used. The Th/K ratio provided the strongest agreement with the groundwater-favorable zones, with an accuracy of 0.601, precision of 0.632, recall of 0.857, and F1-score of 0.728. The U/Th ratio provided complementary support, with an accuracy of 0.537, precision of 0.571, recall of 0.828, and F1-score of 0.676. These results indicate that the proposed workflow provides a reproducible and physically meaningful framework for regional-scale groundwater prospectivity mapping in structurally complex arid hard-rock terrains.</p>