Analysis of Rainfall Characteristics and Flood Incidences in Ogun River Basin, Nigeria

International Journal of Research and Innovation in Applied Science (IJRIAS) | Volume V, Issue XII, December 2020 | ISSN 2454–6186

Analysis of Rainfall Characteristics and Flood Incidences in Ogun River Basin, Nigeria 

B.S. Awe*, M.O.Lasisi and F.S. Omotayo
Department of Agricultural and Bio-Environmental Engineering, The Federal Polytechnic Ado Ekiti, Ekiti State, Nigeria
*Corresponding author

ABSTRACT:- This study examined rainfall characteristics in the Ogun River Basin concerning flood situations in Ogun and Lagos State through the release of water from Oyan dam. The research objectives are to analyse the rainfall characteristics and determine its effect on flood incidence in Ogun and Lagos State. 20 years rainfall data of the area, sourced from Tropical Rainfall Measuring Mission (TRMM) was used for the analysis. Height Above the Drainage (HAND) model with Terrain Analysis Using Digital Elevation Models (TauDEM) to delineate the flood-prone area. The result of the trend shows the potential of the future intensity of the monthly rainfall due to an increase in urbanization and which may result in extreme flood scenarios. The high amount of rainfall in the area triggers the continuous release of water from the Oyan dam, which has increased the occurrences of downstream flooding in the lower part of the Ogun Basin. The general rainfall trend is not statistically significant since the significance level is greater than 0.1 and the rate of change (Q = 4.94E-01 mm/year) is very low. This potentially indicates that the current trend of rainfall will not change. However, the potential increase in the population, urbanization and climate change in the study area can contribute to an increase in future flood occurrences.

Keywords: Climate change, Rainfall, Flood, Urbanization and Disaster

1. INTRODUCTION

The earth’s climate has been dynamic since inception and also, the rapidity, frequency and severity of the consequences of climate change in the last few decades are however increasing at in alarming rate (NRC, 2010). According to Afangideh, et al. (2013), the recent and future manifestation of climate change include global warming (increase in temperature), rise in sea level, shifting of global climate zones, changes in the intensity, quality, duration and general pattern of rainfall leading to drought, desertification and flooding; melting of glaciers/polar ice and increased incidences and severity of extreme weather events, among other effects.

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