Abstract
BackgroundRainfall variability exceedingly affects agriculture in Ethiopia, particularly in the eastern region where rainfall is relatively scarce. Hence, understanding the spatiotemporal variability of rainfall is indispensable for planning mitigation measures during high and low rainfall seasons. This study examined the spatiotemporal variability and trends of rainfall in the West Harerge Zone, eastern Ethiopia.MethodThe coefficient of variation (CV) and standardized anomaly index (SAI) were used to analyze rainfall variability while Mann-Kendall (MK) trend test and Sen’s slop estimator were employed to examine the trend and magnitude of the rainfall changes, respectively. The association between rainfall and Pacific Ocean Sea Surface Temperature (SST) was also evaluated by Pearson correlation coefficient (r).ResultsThe annual rainfall CV during 1983–2019 periods is between 12 and 19.36% while the seasonal rainfall CV extends from 15–28.49%, 24–35.58%, and 38–75.9% for average Kiremt (June–September), Belg (February–May), and Bega (October–January) seasons, respectively (1983–2019). On the monthly basis, the trends of rainfall decreased in all months except in July, October, and November. However, the trends were not statistically significant (α = 0.05), unlike in November. On a seasonal basis, the trends of mean Kiremt and Belg seasons rainfall decreased while it increased in Bega season although it is not statistically significant. Moreover, the annual rainfall showed a non-significant decreasing trend. The findings also revealed that the correlation between rainfall and Pacific Ocean SST was negative for Kiremt while positive for Belg and Bega seasons. Besides, annual rainfall and Pacific Ocean SST was negatively correlated.ConclusionsHigh spatial and temporal rainfall variability was observed at the monthly, seasonal, and annual time scales. Seasonal rainfall has high inter-annual variability in the dry season (Bega) than other seasons. The trends in rainfall were decreased in most of the months. Besides, the trend of rainfall decreased in the annual, Belg and Kiremt season while increased in the Bega season. The study also indicated that the occurrence of droughts in the study area was associated with ENSO events like most other parts of Ethiopia and East Africa.
Highlights
In recent decades, climate change and variability generate a significant impact on the environment, society, and economy globally (IPCC 2007; Tierney et al 2013; Birkmann and Mechler 2015; Wang et al 2018)
The findings revealed that the correlation between rainfall and Pacific Ocean Sea Surface Temperature (SST) was negative for Kiremt while positive for Belg and Bega seasons
The study indicated that the occurrence of droughts in the study area was associated with El Niño/Southern Oscillation (ENSO) events like most other parts of Ethiopia and East Africa
Summary
Climate change and variability generate a significant impact on the environment, society, and economy globally (IPCC 2007; Tierney et al 2013; Birkmann and Mechler 2015; Wang et al 2018). In many African countries, more than 85% of the population is engaged in rain-fed agriculture (Diro et al 2011; Mulugeta et al 2019). Due to this, they are exceedingly susceptible to anomalously high and/or low rainfall amounts (Anyah and Qiu 2012; IPCC 2018). The impact of climate change on the developing countries is higher than developed countries since their adaptive capacity is very low (IPCC 2014). Rainfall variability exceedingly affects agriculture in Ethiopia, in the eastern region where rainfall is relatively scarce. This study examined the spatiotemporal variability and trends of rainfall in the West Harerge Zone, eastern Ethiopia
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