Variation in Annual Rainfall Data of Forty Years (1978-2017) for South-South, Nigeria

In this study the annual rainfall data of forty years (1978-2017) for South-South, Nigeria was collected from the archive of NiMet. Three methods were used for the analysis; statistical differences between two the equal-length time scales, coefficient of variability and the anomaly approach. The trend analysis using t-test, Sen’s estimator slope and Mann Kendall were also carried out in order to determine the trend in the rainfall variables. The results show that the differences between the two means of the equal-length time scales revealed variability of 7.00mm. Similarly, the CV of rainfall was 0.145 signifying low variability. However, the anomaly results revealed that 21 years (52.5%) recorded less rainfall; while 19 years (47.5%) recorded much rainfall. The Sen’s estimator slope revealed downward trend of 94mm/yr in 1978-1987 decades; while it recorded upward trends of; 90mm/yr, 30mm/yr and 118mm/yr during the 1988-1997, 1998-2007 and 2008-2017 decades respectively. This study has further revealed that there are variations in the rainfall. Consequently, there is an optimum need to sensitize the general public about its existence in order to take the necessary measures and adaptation options for its mollification and management.