RAINFALL VARIABILITY OVER GUSAU AND ENVIRONS, ZAMFARA STATE, NIGERIA

Abstract

ABSTRACT: This study aims to determine trends in long-term monthly rainfall using nonparametric methods (i.e. the Mann-Kendall and Sen’s T tests) in Gusau North-Western Nigeria. Monthly rainfall records of Gusau synoptic stations for a period 60 years (1953-2012), were acquired from the Nigerian Meteorological Agency. The result revealed that the monthly rainfall recorded downward trend in the months of April, June, July, August and September within 1953-2012. While an upward trend in May and October was recorded but they were significance at 95% confidence level. The s Sen’s slope estimator revealed that of the seven (7) rainy months considered (April, May, June, July, August, September and October) only two months May and October showed upward trends with rainfall of 0.028mm and 0.182mm as obtained by Sens’s slope estimator, while from of month of June, July, August and September there were downward trends of -0.492mm, -0.580mm, -0.069mm and -0.016mm. The implication of the findings is that the area experience some basic indices of climate change.