Spatio-temporal Variability and Trends of Rainfall and Temperature Over Gamo Gofa Zone, Ethiopia

Abstract

This study examined spatiotemporal climate variability and trends of observed rainfall and temperature data from 1991-2010 over Gamo Gofa zone, southern Ethiopia. Normalized anomaly and coefficient of variation were analyzed to observe the variability of climate. Linear regression was used to analyze trends; Mann Kendall trend test was used for testing the significance and ArcGIS was used to map trend magnitudes and the statistical significance. Normalized anomaly of annual rainfalls showed the variability of dry and wet years at all stations. Coefficient of variation analysis indicated that variability of annual and seasonal rainfalls increased from west to east and to the south. Annual, June to August and September to November rainfalls showed both significant decreasing and increasing trends at different stations in the zone. Generally, most of the land area of the zone had experienced insignificant trends for both annual and seasonal rainfalls. Normalized anomaly of mean maximum and minimum temperature showed 2000s were warmer than 1990s at most of the stations. Mean annual and seasonal maximum temperature at all stations in the zone showed warming trends. Significant land of the zone had experienced both warming and cooling trends of minimum temperature for annual and seasonal timescales. These may result in failure of agricultural production that necessitates developing and implementing systematic planning and management activities in the crop calendar.