Spatiotemporal Variability of Rainfall as an Evidence of Changing Climate over the Nigerian Niger Delta

Abstract

This study assesses the spatial and temporal variability of rainfall over the Niger Delta area (Benin, Calabar, Port Harcourt and Uyo) in Nigeria between 1990 and 2020. The daily rainfall data used for this study were obtained through secondary source from NASA’s POWER (Prediction of Worldwide Energy Resources). Coefficient of variation, standardized anomaly index (SAI), precipitation concentration index (PCI) and seasonality index (SI) were used to evaluate rainfall variability and seasonality. The results of temporal analysis of annual rainfall indicated that Benin had the highest annual rainfall amount in 2000 and lowest in 1999 while Calabar and Port Harcourt had their highest rainfall amount in 2007 with the lowest occurring in 1991 and 2014 respectively. Uyo had the highest in 2000 and lowest in 2014. SAI also witnessed the presence of interannual variability of rainfall with negative and positive anomalies in 59.46% and 40.54% of the analyzed years, respectively. PCI and SI results implied that the Niger Delta area had strong irregular rainfall distribution. The results confirm the meteorological sensitivity to locations and provide support for the implementation of station and regional meteorological hazards prevention and to support the mitigation of hazards and improve the management practices of environment system in Niger Delta area.