Water erosion poses a major threat to soil resources and land sustainability in Mediterranean semi-arid environments. This study aimed to assess potential water erosion susceptibility, characterize the spatial distribution of observed erosion forms, and identify priority areas for soil conservation in the Nfifikh watershed (approximately 800 km²), northwestern Morocco. An integrated geospatial approach was adopted, combining the PAP/CAR methodology, Geographic Information Systems (GIS), remote sensing, visual interpretation of high-resolution satellite imagery, and field observations. Spatial correspondence between potential erosion classes and observed erosion forms was examined through spatial overlay analysis, while their statistical association was assessed using a Chi-square test of independence and Cramér’s V. The results indicated that approximately 41% of the watershed was classified as having high or very high potential erosion susceptibility, whereas 20% exhibited moderate susceptibility. The inventory of observed erosion forms revealed the predominance of sheet erosion (63%), followed by gully erosion (22%), with the latter concentrated mainly in the upper watershed. Statistical analysis revealed a significant but weak association between potential erosion classes and observed erosion forms (χ²(20) = 2012.91, p < 0.001; Cramér’s V = 0.157). Integrating potential erosion susceptibility, observed erosion forms, and land-use information enabled the identification of priority intervention areas and the formulation of differentiated soil conservation measures for agricultural and forested lands. These findings highlight the practical value of combining predictive erosion susceptibility mapping with systematic inventories of observed erosion forms to support spatially targeted soil conservation and sustainable watershed management.