Analysis of Rainfall Characteristics in Billiri, Gombe State, Nigeria

Abstract

This study examined the patterns of rainfall in Billiri. Rainfall data for 40 years from 1977 to 2016 were collected from the Gombe State Agricultural Development Program (GSADP) Ladongor station in Billiri. Descriptive statistics for both rainfall and rainy days and the Seasonality Index (SI) of the rainfall were determined. Linear time series analysis was used to determine the nature of the trend of both rainfall and rainy days. To identify variation within the trends, both the rainfall and rainy days series were divided into four-decade2, ten (10) years each from 1977-1986, 1987-1996, 1997-2006 and 2007-2016. Spearman’s rank correlation was used to determine the relationship between rainfalls total and the number of rainy days, the result of the statistics shows that the maximum and minimum rainfall were 1407.9mm, and 363mm respectively while the maximum and minimum rainy days were 60 and 27 days respectively. The SI of the station was markedly seasonal with a long drier season and there are more years of negative anomalies than positive anomalies. The linear trends show that both the rainfall and the number of rainy days decreased over time. There was a change in the patterns of rainfall and rainy days in each decade. A very weak relationship existed between rainfall totals and the number of rainy days. The study recommends that the agricultural extension workers should inform the farmers about the recent trends of rainfall in the study area.