Temperature and Precipitation Trend Analysis and Implications for Hydropower Infrastructure in the Omo-Gibe River Basin, Ethiopia

Abstract

This study examined long-term trends in temperature and precipitation in the Omo–Gibe Basin of Ethiopia and explored their implications for hydropower infrastructure. Climate data spanning 32 years (1987–2019) were obtained from 15 meteorological stations across the basin. To ensure reliable trend analysis, Levene’s test was applied using SPSS to identify and exclude stations with inhomogeneous data. Data consistency was further checked using the double mass curve method, which compares cumulative climate records to confirm uniformity among stations. Missing climate records were filled using the inverse distance weighting (IDW) interpolation method. Trends in temperature and precipitation were analyzed using the Mann–Kendall test and Sen’s slope estimator implemented in R, allowing both the direction and statistical significance of changes to be assessed. The results show a clear warming trend across the basin. Statistically significant increases in both minimum and maximum temperatures were detected at 11 of the 15 stations, while two stations showed decreasing trends and two exhibited no significant changes. In contrast, precipitation generally declined, with 11 stations recording significant downward trends. The remaining four stations showed no significant monotonic trends in either annual or seasonal rainfall. These changes in temperature and precipitation patterns have important implications for hydropower development and operation. Rising temperatures and declining rainfall can intensify soil erosion, leading to increased sedimentation in reservoirs. Higher sediment loads reduce reservoir storage capacity and can damage turbines and other mechanical components, increasing maintenance costs and lowering overall efficiency. Overall, the findings highlight a warming and drying trend in the Omo–Gibe Basin and emphasize the need to account for climate variability and change in hydropower planning, design, and management. Integrating climate-resilient strategies into hydropower infrastructure and operations is therefore essential to reduce risks and ensure long-term sustainability in the face of climate change.