Flood Frequency Analysis of Ogun River Basin

ABSTRACT
Flooding is one of the most common and devastating natural disaster, characterized by the overflow of water onto land that is usually dry. This study analyses flood risk of Ogun River Basin, Nigeria. Flood frequency analysis was carried out on rainfall data from Ogun River Basin at west region of Nigeria, from 1993 – 2023 as the rainfall is the primary cause of flooding in the study area. Normal Distribution and Log Normal Distribution model are used to assess their suitability for predicting flood return period of 5, 10, 15, 50 and 100 years respectively. The result showed 127.60mm, 138.14mm, 144.74mm, 156.72mm and 163.22mm for Normal Distribution. While, 116.94mm, 128.83mm, 136.77mm, 152.75mm and 161.80 for Log Normal Distribution. From the analysis, Normal Distribution was selected as the appropriate model used for the study area than Log Normal Distribution. The results of the analysis provide crucial insights into the potential severity and frequency of future flood events which are essential for flood risk management, infrastructure design, and disaster preparedness in Ogun River Basin. Further research into alternative statistical models, such as the Gumbel or Generalized extreme value (GEV) Distributions, could provide additional insights into the behavior of extreme events in Ogun River Basin and offer better tools for flood risk estimation.
Keywords: Flood, distribution, river, basin, analysis, frequency, flooding, disaster