ABSTRACT
Flooding of settlements around river basins is a global problem, but responses and mitigating issues tend to vary with planning efficiency and technological development. The present study assessed urban growth and its impact on flood vulnerability in a flood-prone urban settlement in southwestern Nigeria and also determined the perception of the victims. Data evaluated were daily rainfall and monthly runoff records of the main river (River Osun) as well as multi-date Landsat imageries for the 1986–2020 period. In addition, the perception of the stratified samples of residents in the study area was obtained using Open Data Kit (ODK) to link the extent of urban growth and flood vulnerability. The image data were classified while the rainfall data were classified for standardised precipitation index (SPI). Also, runoff–rainfall relationship analysis and vulnerability maps were produced using the multi-criteria approach in GIS. The results showed a significant impact of human/anthropogenic variables (including increased built-up, de-vegetation, and poor waste management) as flood-exacerbating factors in the area. The use of GIS also made the multi-criteria approach (which provides better explanatory variables than non-GIS-based analysis) possible in the area. The study concluded on the effectiveness of GIS to provide a better flood decision-support system than single-based, standalone models.
