Time series analyses of mean monthly rainfall for drought management in Sokoto, Nigeria

Abstract

This paper analyses the time series characteristics of rainfall data for Sokoto metropolis for 40 years with a view to understanding drought management. Data for this study was obtained from the Nigeria Metrological Agency (NIMET), Sokoto Airport; Sokoto. The data was subjected to time series tests (trend, cycle, seasonal and decomposition analyses) using additive and multiplicative modeling approach. The results showed an increasing trend of rainfall amount over the metropolis within the period under review. Analysis of seasonality in monthly precipitation showed a concentration of rainfall in the months of June, July and August while it decreases in September; however, the months of March, April, and October do experience some showers of rainfall sometimes. Obviously, result of the seasonality analysis showed that January, February, March, April, May, November and December are dry months. This implies that growing season in Sokoto do end around September. The implication is that farmers in the study area need to stream line their farming activities with a view to making effective use of the available rainfall. The paper also suggests a need for building micro dams, developed underground water resources and or adopts conjunctive water management as part of drought management efforts.

Keywords: Rainfall, seasonality, cycle, decomposition, multiplicative modeling, drought