Characterizing Current and Future Rainfall Variability and its Effect on Wheat and Barley Production in Sinana District, South Eastern Ethiopia

This study was undertaken in Sinana district to analyze current and future rainfall variability and its effect on wheat and barley production in Sinana district. Data on rainfall and crop yield were obtained from National Meteorological Agency and Sinana District Agricultural Offices, respectively. Following data quality checking, rainfall data (current and future), correlation and regression studies were analyzed using Statistical software like Instat V3.36 and SPSS V20. Downscaling the output of CSIRO-Mk3.6.0 GCM model (daily rainfall data) for RCP4.5 emission scenario using a web based software tool (Marksim GCM) for the period 2020-2049 were used to determine trends of annual and seasonal total rainfall and ascertain its impact on yield. Besides, a proportional size method was used to determine 161 sample respondents. Systematic random sampling method was employed to select respondents from Hora-Boqa kebelle for interview. This study used mean, coefficient of variation, correlation and regression analysis to ascertain the relation, cause and effect relationship between rainfall characteristics and wheat and barley yields. The results indicated that the mean onset date of the main rain season (JJAS) for Robe and Sinana station was 1st July. Furthermore, the results of Pearson Correlation Coefficients indicated that duration of kiremt rainy season and kiremt rain had moderate and strong positive relationship (r = 0.488 and r = 0.702) with wheat and barley, respectively in the study area. It was also observed that fifty percent of total variance of crop yield is explained jointly by kiremt rainfall total and rainy day (R2 value are 51.2%). The results of the linear trend analysis indicated that annual rainfall will be increased by 0.16 mm and 0.86 mm every ten years for Robe and Sinana stations respectively. The result of projected wheat and barley yield indicated that there will be a slight decrease in both crops yield (qt/ha) by 2020, 2030 and 2049 years due to the impact of expected weakening of rainfall feature. The study revealed that Spider web, cold air, cloud movement and group of stars seen on the sky were the signs and signals identified by local communities which indicates whether the coming season will experience excessive or deficit rainfall. Taking in to account the above findings, it could be suggested that the farmers’ community are encouraged to utilize timely climate information issued from National Meteorological Agency of Ethiopia (NMA) for farm level decision to enhance their crop yield under changing climate.