Rainfall Variability and Trend Analysis over Lokoja, Nigeria

Abstract

Studies on rainfall variability and trends are of great importance, particularly to the nations where rain-fed agriculture is predominant. This study used CRU data (CRU_TS 4.01) to examine the temporal variability of rainfall data over Lokoja. Statistical tests were employed to examine variability and trend in monthly, seasonal and annual time series. Analysis of variability showed that the rainy seasons and annual rainfall had less variability (CV < 20), but the variability was high (CV > 30) in some months in the rainy season (April, July and August). Standardised precipitation index showed alternation of wet and dry period conditions had been witnessed in the study area. Trend analysis showed more positive trends had been experienced from 1970 through 2010. The variability in rainfall and the increasing trend may have a tremendous effect on water resources availabilities and vulnerabilities of Lokoja.