One-Dimensional Hydraulic Modelling of River Ona Bridges, Ibadan, South-Western Nigeria
1* Ganiyu, H. O., 1 Adeogun, A.G., 1 Sheriff, B. and 2 Na’allah, A. .
1Department of Civil & Environmental Engineering, Kwara State University, Malete, Kwara State, Nigeria
2Department of Civil Engineering, Kwara State Polytechnic, Ilorin, Kwara State, Nigeria.
DOI: 10.36108/laujoces/3202.01.0110
Abstract
Bridges are crucial for transporting people and goods, but their failures can be catastrophic, resulting in loss of life and property. This study assessed the flood stage of selected bridges (Alaafin Avenue, Seven-Up, and Oluyole) along the Ona River, Ibadan, Nigeria, using a one-dimensional model called the Hydraulic Engineering Center-River Analysis System (HEC-RAS). The model requires two major input data: geometric and steady flow data. The geometric features of the study area (stream centerline, riverbanks, flow paths, cross-sections, and bridges) were generated from the Digital Elevation Model (DEM) in HEC-GeoRAS, an extension of ArcMap GIS. The MapWindow Soil and Water Assessment Tool (MWSWAT) was used to predict flow. The input data for the model include DEM, Land use, soil map data, and meteorological data obtained from the Nigerian Meteorological Agency (NIMET). The flood stages of the three bridges were predicted in the HEC-RAS model and the results showed that Alaafin Avenue, Seven-Up and Oluyole bridges had predicted flood stages of 1.5 m, 1.6 m, and 2.5 m and a freeboard minimum clearance of 2 m, 0.3 m, and 0.5 m respectively. However, the predicted flow (75.25 m³/s) was compared with the corresponding value of the flow in ERA (2002) for a free board minimum clearance. It was shown that only Alaafin Avenue Bridge is safe while Seven-Up and Oluyole bridges are prone to inundation by approximated values of 0.3 m and 0.5 m respectively. Therefore, regular inspection and maintenance of bridges are recommended to prevent inundation.
Keywords: HEC-RAS, Bridge, MWSWAT, Ona River, Flood Stage