Local spatiotemporal variability and trends in rainfall and temperature in the central highlands of Ethiopia

This study evaluates recent spatiotemporal variability and trends in rainfall and temperature in the central highlands of Ethiopia by using monthly rainfall and temperature records. The monthly rainfall data are for 132 points of 10x10km grids reconstructed from weather stations and meteorological satellite observations, which cover the period between 1983 and 2013. The monthly maximum and minimum temperatures are for the same points and girds, but cover the period 1981-2011. Linear regression is used to each of the 132 grid points to detect changes or trends in rainfall, maximum and minimum temperatures and the statistical significance of the trends is determined by the F-distribution test. These points were reclassified into the three districts (Woredas in Amharic) studied having different agroecologies by extraction techniques with ArcGIS 10.1 and converted into raster to generate surface data using simple krigging interpolation technique. Annual and June-September (Kiremt) rainfall exhibit statistically insignificant increasing trends in most of the grid points while March-May (Belg) rainfall shows significant decreasing trends. On the other hand, significant spatiotemporal variability in the maximum and minimum temperatures is observed across the study area. The warming trends in the maximum and minimum temperatures for Basona Werana and Efratana Gidim, respectively, are statistically significant at p=.05 and p=.01 levels. It is concluded that trends of rainfall and temperature vary considerably within the study area. This indicates the need for local-level analysis, and context-specific planning and implementation of climate change adaptation interventions.