A temporal analysis of rainfall characteristics on the Jos Plateau, Nigeria

Jos Plateau practices rain fed agriculture which is completely dependent on rainfall which in turn is highly variable in time and space. The timing of rainfall availability has been proven to be more important to crops than its amount and duration. It is for this reason that the present study examines some important rainfall characteristics such as annual rainfall amount, length of rainy season, seasonality index, onset and cessation dates of rainfall on the Jos Plateau using monthly rainfall data obtained from the head office of Nigerian Meteorological Services department for a period of 30 years (1988 – 2017). Appropriate statistical techniques were used in calculating each index. Major findings shows that none of the indices calculated remain stable from their mean over time. The mean annual rainfall on the Jos Plateau for the study period was found to be1245.020 mm with a standard deviation of 139.28 mm. The mean length of raining season for the study period was found to be 173 days with a minimum occurrence of 129 rain days occurring in the year 2017, and a maximum of 203 rain days occurring in the year 2003. The same variability was observed with seasonality index, onset and cessation dates with mean values of 0.94, 14th April and 3rd October respectively. It was therefore observed that since the rainfall characteristics studied exhibited high variability, this might be the major determinant in yield variability of crops in the study area. The research therefore concludes that further studies should be planned towards establishing the relationships between the studied indices and crop yield on the Jos Plateau. Keywords:  Agriculture, rainfall, characteristics, variability and relationship