STATISTICAL ANALYSIS OF RAINFALL CHARACTERISTICS IN AKURE, ONDO STATE.

ABSTRACT

This study examines the trends, onset, cessation and growing season of rainfall over Akure using data obtained from the archive of Nigerian Meteorological Agency (NIMET) Oshodi, Lagos, over the period of 1970-2005. Standardized Precipitation Index (SPI) was estimated from the available Rainfall records, Decadal analysis of Akure indicated 1991-2000as a wet decade, while 1981- 1990 was a dry decade. The onset and cessation dates were determined. The estimated parameters were subjected to time series analysis. Evaluation of trends was done using the Mann-Kendall test. Trend lines for each of the parameter were produced. The length of growing season in the study area ranges between 196 to 287 Julian days, the mean cessation date of the is about 310 Julian day and on the average, the rainy season starts from the 62 Julian day. The Mann-kendall statistic was used to investigate the significance of these trends. The results show that the rainy season has progressively been starting late. The results also indicated that the hydrological growing season is decreasing. The results of this study have great implications for both surface and underground water resource management, agriculture and sustainable food security not only for the Akure region but the state a at large. Increased irrigation agriculture is eminent in this environment

Key words: Cessation, Growing season, Onset, Trends, SPI