Analysis of Rainfall Trend and Pattern in Owerri, Imo State, Nigeria

Abstract

The study analyzed the rainfall trend and pattern for Owerri municipal, Imo state. The data collected is secondary. A remote sensing daily rainfall data from 1981 to 2020 from CHIRPS data archive given in millimeter (mm) was downloaded. In order to achieve the aim of the research, data analysis was conducted on the rainfall data. Some of the statistical methods used includes mean, variance, standard deviation, coefficient of variation, and standardized anomaly index (S.A.I). The annual rainfall and monthly rainfall for Owerri municipal, Imo state were analyzed and charts were presented which show fluctuation in rainfall trend and pattern. The least annual rainfall happened to be in 1983 of about 1662.9mm, which is followed by that of 2001 of 1828mm. The wettest annual rainfall occurred in the year 1995 of 2962.2mm which happened to be the peak of the study, followed by 1999 of 2837.9mm. It was shown that the month July from 1981 to 2020 experienced more rainfall than that of August. The four decadal rainfall presented for the study shows; near normal condition to very wet condition (1981 – 1990), near normal condition (1991 – 2000), extremely dry conditions to near normal condition (2001 – 2010), and near normal condition to extremely dry condition (2010 - 2020). The hypothesis was tested using chi-square, the results shows there is no significant difference in trend and pattern of rainfall in owerri, thus, the null hypothesis was accepted. The study generally show there is a little or no singnificant change in the rainfall pattern and trend in Owerri from 1998-2020 and hence recommend that there should be more monitoring of rainfall activities in order to curtail it excesses in flooding and agricultural loss.