Assessment of meteorological drought and its association with global climate drivers in Genale Dawa River Basin, South‑East of Ethiopia

Abstract

The Genale Dawa River Basin (GDRB) frequently experiences drought, making it important to understand how drought conditions have changed over time in the region. To assess the evolution of drought characteristics, we analyzed the patterns of drought in the GDRB from 1990 to 2020 using the Standardized Precipitation Evapotranspiration Index (SPEI). We also examined the relationship between the SPEI drought index and global climatic factors using the Pearson correlation coeffi cient (r). By applying the run theory, we identified the occurrence, duration, severity, intensity, and peak of droughts in each zone in the basin. Additionally, we used the Modified Mann-Kendall trend test to detect significant trends in the SPEI and drought indicators for each zone using the R software package. Our results indicate that the southern and southeastern regions of the basin experienced varying levels of drought, while the northern half was consistently affected by severe drought. On average, a drought event occurred once every 3–5 years in the basin. Furthermore, we observed that La Nina events were mainly associated with drought in the Belg season, while El Nino events were more linked to drought in the Kiremt season. The Nino3.4 index was found to be a useful indicator of the meteorological drought in the GDRB, suggesting its potential use as a drought predictor for the basin. In the region’s northernmost regions, we discovered a statistically significant ten dency toward increased dryness, but no such trend was seen in any other regions. Based on the results, it is recommended that conducting a comprehensive analysis using multiple drought indices under changing climate conditions is essential in future studies. The findings from the present study can be valuable for policymakers and stakeholders in developing effective strategies to mitigate the impact of droughts on agriculture and water resources management in GDRB.