Spatiotemporal Analysis of Climate Variability and Trends in West Arsi Zone, South‐Central Ethiopia

Abstract

The objective of this study was to evaluate the historical trends and variability of rainfall and temperature and to estimate the extent of change across various agroecological zones (AEZs) in the West Arsi Zone of south‐central Ethiopia from 1983 to 2019. Data on daily temperature and rainfall were collected from the Ethiopian Meteorological Institute. The study utilized the Mann–Kendall test, Sen’s slope estimator, and descriptive statistical methods to analyze data and identify trends. The analysis revealed a significant increase in mean annual temperature (p < 0.001) with 0.045°C per annum. The lowland and midland experienced significant increases in mean annual temperature (p < 0.001) by 0.063°C and 0.094°C per year, respectively, while insignificant increase was found in the highland AEZ. Analysis of rainfall revealed high interannual and seasonal variability, with the highest rainfall variability observed in the lowland. The analysis also revealed the study area experienced a significant decrease in annual average rainfall (p < 0.01) by 3.704 mm and Belg rainfall, short rainy season from mid‐February to May (p < 0.05) by 22.46 mm per year. The annual number of rainy days (RDs >1 mm) shows a significant decreasing trend (p < 0.001). The analysis further revealed decreasing trends of rainfall in all AEZs where the midland experienced a significant decrease in annual rainfall (p < 0.01) by 8.72 mm and Belg rainfall (p < 0.05) by 4.734 mm. In the Kiremt rainfall pattern, there was a decreasing wet spell and an increasing dry spell, and the annual rainfall coefficient of variation (CV) was 17.22% in the highland, 26% in the midland, and 32.36% in the lowland. Overall, the detected alterations in rainfall patterns, coupled with their considerable variability, are expected to negatively affect rain‐fed agriculture and the environment. The results of this study are anticipated to offer crucial insights into the spatiotemporal variability and climate trends, aiding decision‐makers and development planners in crafting tailored strategies to enhance climate resilience.