Spatial and Temporal Uncertainty of Rainfall in Arid and Semi-Arid Areas of Ethiopia

Abstract

The aim of this study was to assess rainfall uncertainty and trends in the arid and semi-arid areas of Ethiopia by using rainfall data records from the thirteen stations over the period of 1952-2012. In this study, annual and seasonal rainfalls were analyzed for trends, least square regression was used to quantify the trends and Spearman's rho was used to test statistical significance of the trends. The results of the analysis in rainfall variability shows negative trend in Bulen and Asosa stations in the western arid and semi-arid areas was statistically significant at 0.71 and 0.3 levels respectively. In the same way, inter annual seasonal rainfall shows during observation negative trends for eight to eleven stations, though not statistically significant in most of the stations. The finding of the study revealed that, there are significant spatial differences in mean annual, seasonal and trends of rainfall between the Western and Eastern, South Eastern arid and semiarid areas of Ethiopia.