Desertification poses a critical threat to ecosystems and livelihoods in arid regions, where fragile landscapes are increas-ingly exposed to climatic variability and human pressure. This study aims to evaluate land degradation sensitivity in the Ziz Valley, southeastern Morocco, by applying the MEDALUS model within a GIS-based analytical framework. Multi-source datasets, including satellite imagery (Sentinel-2, ASTER DEM), climatic records (WorldClim), and socio-economic indicators, were integrated to derive four quality indices soil, vegetation, climate, and management - subsequently com-bined into an Environmental Sensitivity Area Index (ESAI). The resulting high-resolution map shows that approximately 71.5% of the valley is highly sensitive to desertification, particularly in the southern oases of Erfoud and Rissani, where aridity, soil erosion, and overgrazing dominate. In contrast, only 12.3% of the area demonstrates low sensitivity. Valida-tion using field surveys yielded an overall accuracy of 90%, confirming the model's reliability. The findings emphasize the effectiveness of geospatial data integration for quantifying land degradation processes in data-scarce arid regions. This research underscores the importance of spatial information science in supporting evidence-based land management, enhancing resilience, and informing sustainable policy for vulnerable oasis ecosystems.