Rainfall Variability and Trend Analysis Over Nguru Yobe State, Nigeria

Abstract

Aims: This study aimed to analyze rainfall variation in a semi-arid environment by examining the annual precipitation over Nguru in Yobe, Nigeria for a period of 31 years (1975-2005). Place and Duration of Study: The study was conducted in Nguru town, an arid environment in Yobe State of Nigeria using rainfall data from Nguru meteorological station from 1975-2005. Methods: Coefficient of variability (CV) was used to evaluate rainfall variability over time in the area, and non-parametric Mann-Kendall and Sen’s slope estimator were used to determine rainfall trend and its magnitude in the study area. The investigation was based on data collected over a 31-year period at a single site. Results: The result indicates that the coefficient of variation CV for the annual rainfall in Nguru revealed a moderate inter annual variability (25%), whereas the CV for seasonal rainfall demonstrates that rainfall in the May June July monsoon period is highly variable between seasons (more than 40%). The CV for the August September October monsoon period, on the other hand, was 31.6%, indicating a considerable and high variability in total rainfall received. Conclusion: The main conclusion of this study is that rainfall is highly variable over the years, posing a threat to climate change-induced drought and, as a result, affecting the socio-economic well-being of the people in the area, who are mostly peasant farmers who rely solely on agricultural activities for their livelihood.