Trend Analysis of Extreme Rainfall Events for Decision-making in North-West Nigeria

Abstract

Global climate change have trigger extreme rainfall events leading to meteorological hazards around the world. This paper examines the trends in extreme rainfall from five (5) synoptic stations in North-West Nigeria for a period of 35 years (1981-2015). Daily rainfall data acquired from Nigeria Meteorological Agency were converted into indices (heavy, very heavy, extremely heavy rainfall days, one day maximum rainfall amount and five days maximum rainfall amount). Statistical tests of Mann-Kendall Test (MK), based on non-parametric approach to trend detection were used to evaluate the possible trend in the derived indices. Results showed significant positive trends in the five indices at Kano and Kastina station. The insignificant positive trends were detected in the indices across other station with exception to Gusau for heavy, very heavy rainfall days and Yelwa for five days maximum rainfall amount where the trends were negative. The trends were attributed to a possible change in climate. It is recommended that similar research, utilizing longer-term data extending to entire Nigeria, to facilitate generalization of the outcome of this finding.