CLIMATE VARIABILITY AND ITS IMPACT ON WHEAT (Triticum aestivum L.) YIELD IN SELECTED WOREDAS OF SOUTH EASTERN ZONE OF TIGRAY, NORTHERN ETHIOPIA

In Ethiopia in general and the study region in particular, where vulnerability to climate change and variability is high studying the impact of climate change at a local scale is critical for designing appropriate strategies for adaptive capacity. This study was conducted in four Woredas of Tigray Region namely Hintalo Wejerat, Degua Tembien, Enderta and Seharti Samre to examine whether observed climate variables revealed significant change and to assess the impact of future climate on the yield of Wheat. Historical (1988–2017) climate data (rainfall, maximum and minimum temperatures) and Wheat yield data of each Woreda were used in this study. The historical climate data of each Woreda was obtained from the National Meteorological Agency of Ethiopia while the production data was obtained from the Central statistical Agency and Agricultural and Rural Development Bureau. Likewise, future climate data of the study area was downscaled from an ensemble of 17 GCMs under two scenarios (RCP 4.5 and 8.5) and for the period of 2050s and 2080s. Observed climate data was used to analyze the onset date, cessation date, length of growth period, number of rainy days and probability of dry spell lengths of the study area. Furthermore, Instatplus_3.37, Man Kendall trend test and multiple regressions were employed for climate variable, trend test and predict the impact of climate change on Wheat yield in the coming decades. The result revealed that trend of mean annual rainfall totals was decrease in all study station sites, except Samre station and statistically non-significant at 0.05 significant level. Regardless of station the onset date of the kiremt season was on the second decade of July in all station. On the other hand, the annually rainfall stopped early in the second week of September at all study stations. The probability of dry spell length at 5 days were above 20% at Adigudem and Samre and less than 10% at Hagereselam and Mekelle stations during the highest rainfall on June 30 (180 DOY) to August 31 (243 DOY). Moreover, maximum temperature showed increases trend with statistically significant at all station. Similarly, trend of minimum temperatures were increasing except Hagereselam station in the study area. The results indicated that the coefficient of determination value for Hintalo wejerat (0.95), Degua tembien (0.93), Enderta (0.94) and Seharti samre (0.93). The regression models will have projected the yield of wheat yields will decrease in all study areas except Degua tembien area; it will increase by 10.25% and 1.48% under the RCP4.5 and RCP8.5 respectively in midcentury (2050s) compare to the baseline. Whereas, in the end century (2080s) the production of wheat will decrease at all study areas in both concentration pathways (RCP4.5 and RCP8.5).