Analysis of Impact of Exposures and Hydrological Modelling of Flood Peak Zones in Adamawa Catchment, Nigeria

Nwilo P. C.1, Olayinka N. D.1 and Adzandeh A. E.2,*

1 Department of Surveying and Geoinformatics, University of Lagos, Akoka, Nigeria

2African Regional Institute for Geospatial Information Science and Technology (AFRIGIST), Obafemi Awolowo University, Ile-Ife, Nigeria

*Corresponding Author: ayilaj2013@gmail.com

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 Vol. 3 No. 2  | October 2019 | Pages 256 – 267

https://doi.org/10.36263/nijest.2019.02.0148

Abstract

ABSTRACT

During the wet season, the Benue River overflows its banks and sometimes, extreme floods also occur in Adamawa catchment. Intensification of agriculture in some areas and urban growth in other areas has exposed a large population to flood risk. Little is known about localities or areas liable to flood at various peak flows and how land use and soil permeability affects the severity of flood in Adamawa catchment. This study seeks to analyse the exposures of land use/land cover and soil permeability to flood and model flood peak zones for three flow rates (2 years, 5 years and 10 years) using geospatial techniques and HEC-RAS model. Results of 2 years flood show that at least eight localities in the study area are highly prone to flood. This means that the probability of a flood of this calibre to occur and affect those localities in a given year is 50%. The number of localities prone to flood increases for Annual Exceedance Probability of 20% and 10%. The probability of 10% flood to occur and affect those localities in a given year is relatively low compared to both the 2yr and 5yr flood. Modelling results generated a curve number grid map which shows the permeability levels within the study area. Areas with more infiltration capacity recorded 50% (very high) and 20% (high). Moderate permeability score 16%. Very low and low levels account for 7.6% and 5.2% respectively. The implication is that 70% of the total area experience reduced surface runoff whereas 12.9% are more prone to water logging.

Keywords: Adamawa catchment, flood peak zones, Geospatial techniques, HEC-RAS model, land use/land cover, soil permeability to flood

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Nwilo P. C., Olayinka N. D. and Adzandeh A. E., 2019. Analysis of Impact of Exposures and Hydrological Modelling of Flood Peak Zones in Adamawa Catchment, Nigeria. Nigerian Journal of Environmental Sciences and Technology, 3(2), pp. 256-267. https://doi.org/10.36263/nijest.2019.02.0148