Historical Trend Analysis of Rainfall in Amhara National Regional State
Book Chapter
Mesfin, S, Adem, AA, Mullu, A et al. (2021). Historical Trend Analysis of Rainfall in Amhara National Regional State
. 475-491. 10.1007/978-3-030-76437-1_25
Mesfin, S, Adem, AA, Mullu, A et al. (2021). Historical Trend Analysis of Rainfall in Amhara National Regional State
. 475-491. 10.1007/978-3-030-76437-1_25
Ethiopian agriculture is mostly rainfed and is threatened by interannual and seasonal rainfall variability. This study aimed to assess rainfall in the Amhara Region, Ethiopia. Two rainfall datasets: observed and Climate Forecasting System Reanalysis (CFSR) were used. CFSR data was bias corrected using rain gauge data. In order to analyze the rainfall characteristics, Mann-Kendal trend test, Sen’s slope estimator, connected component (CC)-based homogeneity test and seasonality index were used. The results showed that Amhara Region received mean annual rainfall of 1,150 mm. Western part of Amhara Region showed significant increasing trend. Decreasing trend was observed in the remaining part of the region but the trend was not significant at 95% of significance level except for some northeastern part of the region. Amhara Region has three homogeneous rainfall regions: Region 1, 2 and 3. The region also has four major groups of seasons. Area of Region A received 75–80% of rain over five to six months while Region B received this amount of rain in four months. Region C received similar amount of rainfall in three months and Region D received same amount of rainfall in two or less months. In 79% of Amhara Region, rainfall is unimodal and received in wet season. The rest part of the region, 21% and mainly in the eastern part, has bimodal rainfall. From the result, we can conclude that Amhara Region has ample amount of rain but concentrated in few months with considerable variability and trend. Therefore, it is important to adjust the cropping system with the variability of rainfall.
