Assessment of urban surface runoff potential in response to land use land cover changes in the Federal Capital City, Abuja, Nigeria

Rapid urban expansion in sub-Saharan Africa transforms landscapes, yet empirical links between land-use changes and runoff dynamics remain limited, particularly in planned cities like Abuja’s Federal Capital City (FCC), Nigeria. While previous studies documented land use/land cover (LULC) changes in the FCC, none have quantified the multi-decadal hydrological response using integrated remote sensing and hydrological modeling, nor identified district-level runoff accumulation hotspots to guide localized flood planning. This study assess the relationship between LULC changes (1990–2020) and surface runoff dynamics, mapping districts vulnerable to accumulation. Multi-temporal Landsat imagery was classified using a Random Forest algorithm, while the Soil Conservation Service-Curve Number (SCS-CN) model integrated with GIS estimated runoff depth and volume. Vulnerability mapping identified risks across 134 districts, validated using Sentinel-1 SAR flood extents (2018–2020). Results show Built-up areas expanded from 56.9 km² to 247.8 km² (+ 335%), while forest and grassland declined by > 86%. Surface runoff from built-up areas increased from 13.2% to 41.6% of total runoff, and runoff volume rose from 52.93 × 10⁶ m³ to 61.34 × 10⁶ m³. Vulnerability analysis revealed that 44.3% of the FCC (59 of 134 districts) is at high or very high runoff accumulation risk, concentrated in the northern and central zones. This study provides the first district-level, multi-decadal runoff vulnerability assessment for the FCC, proving that urbanization on hydrologically sensitive soils amplifies flood risk. These findings support SDG 11 by identifying priority zones for green infrastructure and stormwater management interventions.