Analysis of Spatiotemporal Trends and Variability in Temperature and Rainfall in the West Wallaga Zone, Western Ethiopia

Agriculture is a crucial sector in Western Ethiopia that provides livelihoods to many people. However, climate change has brought about extreme weather conditions which pose a challenge to the agricultural sector. To combat the negative effects of climate change, adaptation strategies should be designed using historical and projected climate change patterns. This study aims to analyze spatiotemporal trends and variability in temperature and rainfall in the West Wallaga Zone, Western Ethiopia. The analysis used rainfall data from the Climate Hazards Group Infrared Precipitation with Stations (CHIRPS) and satellite-based temperature data from the Nederlands Meteorologisch Instituut (Koninklijk Netherlands Meteorological Institute [KNMI]) covering a period from 1981 to 2022. The coefficient of variation (CV), rainfall anomaly index (RAI), and precipitation concentration index (PCI) were used to determine rainfall variability. The Mann–Kendall (MK) trend test and Sen’s slope methods were used to examine the existence of trends and slope magnitudes of temperature and rainfall. The result revealed a statistically significant increasing trend in annual temperatures. The mean maximum temperature showed higher seasonal variability than the mean minimum temperature for the past four decades. Annual, Bega, Belg, and Kiremt seasons rainfall increases with the trend being significant for all seasons except Kiremt. Spatial and temporal variations in rainfall were detected on both annual and seasonal timescales. Negative and positive rainfall anomalies each accounted for 50% of annual observations, with the highest seasonal negative anomalies occurring during the Belg. The PCI was highly irregular in Belg and uniform in the Kiremt season. Overall, the West Wallaga Zone has experienced moderate rainfall variability and significant warming over the past four decades. These findings provide important evidence to inform targeted adaptation strategies that can strengthen agricultural resilience under a changing climate.