Multi-Temporal Land Use/Land Cover Change and NDDI-Based Drought Assessment in Semi-Arid Gadaref State, Sudan (1985-2022)

This study investigates land use and land cover (LU/LC) dynamics in three semi-arid Sudanese localities-Elsefia, Al-Khayari, and Aliadedat-over the period 1985-2022, using multitemporal Landsat imagery processed in Google Earth Engine (GEE) and ArcGIS Pro. The Normalized Difference Drought Index (NDDI) was derived alongside NDVI and NDWI to assess concurrent drought severity across the study period. Results reveal a consistent decline in rangeland across all sites (-2.5% to-4.7%), accompanied by sharp increases in settlement and agricultural areas. Settlement expansion was most pronounced in Al-Khayari (+10,861%), while agriculture surged in Elsefia (+33,350%) and Aliadedat (+527%), reflecting intensified cultivation and urban encroachment. Flooded vegetation expanded significantly in Elsefia (+296%) and Al-Khayari (+173%), suggesting hydrological variability and ecological adaptation. Bare land trends were mixed, with slight declines in Elsefia and Al-Khayari but localized increases in Aliadedat. These findings highlight a regional transition from natural rangeland toward human-dominated landscapes, driven by demographic pressures, agricultural intensification, and climate variability. The study underscores the need for integrated land management strategies-including community-based rangeland restoration, water-efficient agriculture, and evidence-based urban planning-to balance human development with ecological sustainability in semi-arid Sudan.