A Spacio-Temporal trend analysis of rainfall and its implications for agricultural production in Sudano-sahelian region of Nigeria

Abstract

This study examined the trends in monthly and annual rainfall totals in the Sudano – Sahelian zone of Nigeria. Ten synoptic stations were selected across the region and monthly rainfall records for 60 years (1952 – 2011) were obtained from the Nigerian Meteorological Agency (NIMET) for each station. Descriptive statistics of the long-term characteristics of rainfall were computed for all the stations while dispersion and variability indices (standard deviation and coefficient of variation) were also calculated for all the sampled stations. Anomaly values were computed for all the stations using the Standardized Rainfall Anomaly Index (SRAI). Time series for each station were plotted to present the inter-annual characteristics of rainfall in the study area. Decadal mean rainfall maps of the area were produced using Krigin Interpolation in Arcmap environment of ArcGIS 10.1 software. The results revealed that there was a downward trend in rainfall amounts in the 1970s and 1980s which was responsible for the drought episodes of 1972/73 and 1980 and an upward trend in the amount of rainfall between 1990 and 2011. These downward trends in rainfall resulting in droughts and upland trends resulting in floods have implications for agricultural production in the region. The Federal and States Governments affected by these implications should adopt measures towards tackling the situation in the region.