Examining the Contribution of Urban Land Use Change to Intensification of Pluvial Flooding in Abuja Federal Capital Territory Using a Multi-Decadal Analysis

Pluvial urban flooding, driven by the inability of urban surfaces and drainage systems to accommodate intense rainfall, is an escalating challenge in Nigeria's planned capital Abuja, where decades of rapid peri-urban expansion have transformed the hydrological response of the city's watershed system. This study examines the contribution of urban land use change to intensification of pluvial flooding in Abuja FCT over a multi-decadal analytical period, combining atmospheric, hydrological, and urban planning science methodologies in an original integrated framework. Multi-temporal Landsat and Sentinel-2 imagery was classified for the years 2000, 2010, 2016, and 2022 to quantify LULC transitions across the FCT. Rainfall records from NiMet Abuja Airport and seven supplementary automatic stations were analyzed for trends in extreme rainfall indices. A semi-distributed urban hydrological model (EPA-SWMM) was configured for six representative sub-catchments within Abuja's Jabi, Dutse, and Lugbe drainage systems, incorporating measured storm drainage infrastructure parameters. Controlled model experiments isolating the rainfall intensification and urbanization contributions to changes in flood peak discharge were conducted. Results indicate that urban impervious cover has increased from 12 percent of FCT area in 2000 to 34 percent in 2022. Model experiments attribute 61 percent of observed flood peak intensification to urbanization-induced runoff changes and 39 percent to rainfall trend intensification, confirming that urban expansion is currently the dominant driver of worsening flood outcomes. Original methodological contributions include a land use change attribution methodology for pluvial flooding specific to planned capital city contexts. Keywords: pluvial flooding, urban land use, Abuja, SWMM, attribution.