Comparative assessment of desertification sensitivity in West Africa using standard and FAHP-modified MEDALUS approach.

West Africa faces significant challenges from land degradation and desertification, exacerbated by variables such as fluctuating rainfall and vulnerable soils. Approximately 46% of the land in this region is affected by degradation processes, necessitating a nuanced understanding of spatial variations for efficient land management. This study assesses land sensitivity to desertification using two methodologies: the original MEDALUS framework implemented in Google Earth Engine (MEDALUS-GEE) and an enhanced Fuzzy Analytic Hierarchy Process-based MEDALUS model (FAHP-MEDALUS). The research incorporates 17 ecological and management factors to derive soil, vegetation, climate, and management quality indices, ultimately creating the Environmental Sensitivity Area Index (ESAI). The MEDALUS-GEE approach identified 40.43% (approximately 2.14 million km2) of the study area as fragile and 19.54% (around 1.03 million km2) as critical. In contrast, FAHP-MEDALUS showed a higher sensitivity, classifying 50.77% (roughly 2.69 million km2) as fragile and 37.57% (approximately 1.99 million km2) as critical, thus detecting a more extensive range of highly critical areas. Crucial findings indicate that integrating FAHP-based weighting methods enhances model sensitivity and environmental coherence by accounting for uncertainty in the importance of each factor. The analysis ranks intensive agriculture, low rainfall, steep slopes, high bulk density, water erosion, and poor soil organic matter and vegetation density as the primary triggers of land degradation in West Africa. Furthermore, the FAHP-MEDALUS methodology augments assessment reliability by incorporating fuzzy logic, reducing subjectivity, and improving regional sensitivity differentiation compared to traditional models. Ultimately, the synergy of FAHP and MEDALUS within a geospatial framework presents a robust and adaptable approach for assessing desertification, enabling targeted restoration strategies. This contributes significantly towards achieving land degradation neutrality and fulfilling Sustainable Development Goal (SDG) 15 in semi-arid regions of Africa.