Integrated GIS-based Assessment of Soil Quality Using the MEDALUS Framework in the Nile Delta, Egypt

Abstract Soil quality is crucial for sustaining agricultural productivity, especially in intensively farmed regions like the Nile Delta, where salinity, degradation, and declining fertility threaten soils. The Mediterranean Desertification and Land Use (MEDALUS) framework is widely used in Egypt, but most studies focus on broad land degradation rather than detailed soil quality. This study develops a spatially explicit Soil Quality Index (SQI) for Kafr El-Zayat, Gharbia Governorate, Egypt, integrating field observations, lab analyses, remote sensing, and GIS-based geomorphological modeling. Twenty representative soil profiles were described and analyzed for their physical, chemical, and fertility properties, which were subsequently used to derive the MEDALUS indicators: the Physical Quality Index (PQI), Chemical Quality Index (CQI), and Fertility Quality Index (FQI). Sentinel-2B (2023) imagery and DEM-derived geomorphological units were used to improve spatial discrimination of soil conditions. All indices were integrated in a GIS environment using interpolation, reclassification, and weighted overlay, with the workflow automated in ArcGIS Model Builder to produce a reproducible and efficient final SQI map. The results indicate that 24.3% of the study area exhibits high soil quality, 54.2% moderate quality, and 21.5% low quality. The spatial distribution of SQI is primarily controlled by geomorphology, soil texture, salinity levels, and organic matter content. The enhanced SQI model offers a practical, spatially explicit tool to visualize soil quality variability and identify priority areas for sustainable land management. The integrated MEDALUS–GIS approach is scalable and transferable to deltaic and Mediterranean regions under intensive agricultural pressure. Graphical Abstract This study presents an integrated, GIS-based assessment of the Soil Quality Index (SQI) in the Kafr El-Zayat Province of the Nile Delta, Egypt, using the established Mediterranean Desertification and Land Use (MEDALUS) framework. The workflow begins with acquiring Sentinel-2B satellite imagery for 2023 and a Digital Elevation Model (DEM), both of which were used to delineate the geomorphological units of the study area. Fieldwork included soil profiling and the collection of twenty representative soil samples. These samples were subjected to detailed physical, chemical, and fertility analyses to generate the three MEDALUS indices the Physical Quality Index (PQI), Chemical Quality Index (CQI), and Fertility Quality Index (FQI) All datasets were subsequently integrated within a GIS environment, where the Model Builder in ArcGIS was used to automate the spatial workflow including interpolation, reclassification, indicator mapping, and the computation of the final SQI map. The results indicate that medium SQI dominates (54.15%), followed by High (24.34%) and Low (21.49%) quality zones. The graphical abstract highlights how the integration of multisource data with an automated spatial workflow provides a robust and scalable model for soil quality assessment and land management in deltaic environments. It visually represents this end-to-end process by showing Sentinel-2B imagery as the primary source of remote-sensing data, geomorphological units derived from the DEM, the spatial modeling steps performed within the Model Builder, and the final SQI map spatially integrated with the geomorphological units to reveal the spatial variability of soil quality across the study area.