Land use change, planning instruments, and sustainable strategies for urban flood risk management in Ibadan, Nigeria

The study examined land use/land cover changes in Ibadan, Southwestern Nigeria, from 1990 to 2020. It also assessed flood occurrences, land use planning, and appraise the current flood risk management. Primary data was collected through intensive fieldwork including ground-truthing of flood zones verification. A total of 241 questionnaires were retrieved from the respondents and 50 Key Informants (KIs) from urban flood management agencies were engaged to discuss current strategies in the study area. Secondary data utilized included Digital Elevation Model and satellite images from 1990, 2005, 2010, and 2020 for flood vulnerability assessment using supervised classifier algorithm. All data were analyzed statistically and with Geographic Information Systems (GIS) methods. The results indicated a significant reduction in vegetation cover (49.5%) limiting flood buffer capacity, while built-up areas (3.5%) and bare soil (5%) showed an increase in land use dynamics. Similarly, KIs confirmed cases of flood occurrences, including 1st occurrence (34), 2nd occurrence (12), and 3rd occurrence (4). Respondents agreed that zone regulation (53.5%) and land use planning (78%) helped minimize floods. Findings revealed that strict compliance with planning laws (19.1%) and waste management laws (16.7%) were very effective flood sustainable strategies, while 53.5% of respondents identified different land use planning instruments for managing urban flooding. This study concluded that integrating geospatial analysis with stakeholder interviews evaluated the effectiveness of planning instruments in flood-prone urban zones and sustainable flood reduction strategies.