Long-term trends and projections of climate variability for the Borkena river catchment of the Awash River basin, Ethiopia

Trend analysis of climate variables, such as precipitation and temperature, provides useful information for understanding the hydrological changes associated with climate change. In this study, we quantified and assessed the changes in different hydrological flux components for the Borkena River catchment in the Awash Basin of Ethiopia during the 2030s (2021–2040), 2050s (2040–2060), and 2070s (2061–2080) future periods. To accomplish this, we utilized a multi-temporal approach based on linear regression and the Mann–Kendall test. We used three different regional climate Models (MIROC-MIROC5, MPI-M-MPI-ESM-LR, and SPL-IPSL-CM5A-MR) under two Representative Concentration Pathway emission scenarios (RCP4.5 and RCP8.5). As a result, the GCM projections indicated that the mean annual maximum and minimum temperatures are projected to increase by 0.56 °C and 0.31 °C, respectively, while the mean annual rainfall has been projected to increase in the coming decades. The study also revealed considerable average monthly and seasonal changes in rainfall magnitude and direction. In general, from a hydro-climatic perspective, the outcomes suggest that the study area is moving towards a situation with more severe flood events.