Citation :

Baywood, C. N, Igbokwe, J.I., "Comparative Analysis of Hydraulic Flood Models in Mapping Flood Vulnerable Areas in Abia State, Nigeria," International Journal of Geoinformatics and Geological Science, vol. 13, no. 2, pp. 24-38, 2026. Crossref, https://doi.org/10.14445/23939206/IJGGS-V13I2P103

Abstract

Studying issues and risks associated with flooding is a thing of utmost importance, especially for a developing country like Nigeria. Flooding, being an event that occurs regularly with so many predictions of its constant hazardous effect, there is a pressing need to analyze and understudy the available methodology and ascertain the most suitable, with proven results for modelling flood risk vulnerability. Therefore, this paper, as part of research, is aimed at the analysis and assessment of the accuracy of hydraulic flood models in mapping flood vulnerability areas in Abia State, Nigeria. Its objectives were to: examine the pattern of landcover/landuse; determine the surface runoff potential; model the extent of flood vulnerability using HEC-RAS, TUFLOW, and Flood Modeler; and compare and analyze the results obtained. The methodology involved the acquisition of Sentinel-2 imagery covering Abia State, Rainfall data and ALOS PALSAR. Image subsetting was done to extract the area of study from the acquired dataset. This was followed by analysis of DEM accuracy using root mean square error, image classification to extract the landuse/landcover of the study area, surface runoff modelling to determine surface runoff potential in the study area and hydraulic flood modelling using HecRAS, TUFLOW AND flood modeler. The results indicated that ALOS PALSAR was a fit to be used for flood modeling, as backed by the vertical and horizontal accuracies of 5.64m and 14.39m, respectively. The flood frequency return as modelled by HecRAS revealed a 25.43km2 inundation extent in a 2-year return period, 28.09km2 inundation extent for a 5-year period and 26.67km2 inundation extent for a 10-year return period, increasing to its peak extent by 3.15% by the 5-year return period, then decreasing by 1.8% by the 10-year return period. The flood frequency return as modelled by TUFLOW also revealed a 24.97km2 inundation extent for a 2-year return period, 27.87km2 inundation extent for a 5-year period and 26.10km2 inundation extent for a 10-year return period, increasing to its peak extent by 3.67% by the 5-year return period, then decreasing by 2.24% by the 10-year return period. The flood frequency return as modeled by Flood Modeler indicated a 25.04km2 inundation extent for a 2-year return period, 28.10km2 inundation extent for a 5-year period and 26.04km2 inundation extent for a 10-year return period. Increasing to its peak extent by 3.67% by the 5-year return period, and then decreased by 2.24% by the 10-year return period. The surface runoff potential revealed that 35.99% with an area of 1630.19 km2 had low infiltration potential, 32.51% with an area of 1472.56 km2 had moderate infiltration, while 31.50% with an area of 1426.82 km2 had high infiltration. This indicated that the study area had a great extent of low surface infiltration, which will lead to flooding during heavy or frequent rainfalls. These results indicated that out of the three models tested, HecRAS had the best fit to the ground flood points, and it was recommended to be used as a hydraulic flood modeling option.

Keywords

Flood Vulnerability, GIS, Hydraulic Modelling, Surface Runoff, Hec-RAS, Tuflow, Flood Modeler.

References