Assessment of Hydraulic Adequacy of Selected Culverts for Effective Flood Management in Ibadan Southwest Nigeria

This study assesses the hydraulic adequacy of selected culverts for flood management in Ibadan, Southwest Nigeria. The surface runoff potential and inflow at various culvert sections were analysed to determine their capacity to handle stormwater discharge. The Rational Method, which establishes a direct rainfall-runoff relationship, was employed to estimate storm discharge at different locations along the road alignment. For the hydraulic analysis, the HY-8 tool was used to simulate water profiles, applying the direct step method to calculate the sequent depths. A total of 17 box culverts, varying in number of cells and dimensions, were analysed. The hydrological analysis revealed that the lowest estimated flow occurred at culvert ID 73 with a value of 15.29 m³/s, while the highest flow was observed at culvert ID 40 with 52.78 m³/s. Overall, all 17 culverts were found to have sufficient capacity to convey the design flow. The study concludes that the culverts analysed are hydraulically adequate for managing flood events in the study area, thereby contributing to improved flood control and infrastructure resilience.