Analysing the characteristic-sequence of rainfall amounts in Ibadan, Nigeria

Abstract

Rainfall varies from year to year and over decades, and changes in rainfall amounts affect the environment and society. Steady moderate rains penetrate into the soil and benefit plants, while the same amounts of rainfall in a short period of time may cause local flooding and runoff. Ibadan
has been experiencing yearly severe flooding within and around the metropolis with substantial costs. Despite research endeavours by numerous
researchers, there is limited studies on the analysis of the characteristics of rainfall. This study, therefore analysed the sequence of rainfall amounts in Ibadan. Rainfall data from 1989 to 2018 were retrieved from the archive of the Nigeria Meteorological Agency and Forest Research Institute of
Nigeria meteorological station, Ibadan to examine the dynamics of rainfall amounts. The data were analysed using descriptive and inferential  statistics, at p≤0.05. The result showed that there was no significant relationship between the annual rainfall totals and time in years (-0.119). The study also revealed that there was no significant difference in the mean rainfall amounts between the Nimet and the FRIN stations, with the calculated T-value of 0.89, which was less than the T-critical value of 2.04 at 0.05 confidence level. This indicates that the difference in the mean annual rainfall at the two stations is not significant. The result showed that the Nimet station is not significantly wetter than FRIN station. The results will be used in establishing guidelines for the use of rainwater in agriculture, and the prevention of flooding, runoff and soil erosion in Ibadan.

Keywords: Temporal pattern, Variability, Amount, Decadal rainfall, Period