Evaluation of streamflow response to climate change in the data-scarce region, Ethiopia

Even though many agricultural and infrastructure developments are undertaken in the Upper Blue Nile basin, the possible impact of future climate variation on the streamflow is not considered. Therefore, the goal of this study is to evaluate the impact of climate change on the Megech streamflow and to calibrate and validate the Soil Water Assessment Tool (SWAT) model. The baseline period (1976–2005) and the future period of the 2050s and 2080s were used. The widely accepted Global Circulation Models (GCM) were used to derive the climate data: Canadian Centre for Climate Modeling and Analysis (CanMES2), Model for Interdisciplinary Research on Climate (MIROC), Institute Pierre Simon Laplace (IPSL), Max Planck Institute for Meteorology (MPI). The dynamic downscaling and bias corrections were done for all the GCM data. The Nash–Sutcliffe Efficiency (NSE) values of 0.74 and 0.68 for calibration and validation periods show the capability of the SWAT model for simulation of the streamflow. The result of the models reveals a steady increase in temperature and decrease in precipitation at both time windows for both Representative Concentration Pathway (RCP) 4.5 and 8.5 scenarios. The result of the future scenarios depicted that the mean annual streamflow of the Megech river may rise by 5.9% and 6.5% for the 2050s and 2080s, respectively for the RCP 4.5 scenario, while for the RCP 8.5 scenario, the model shows an increase by 7.3 and 8.3% for 2050s and 2080s, respectively. The multi-model projections revealed that the Megech watershed is likely to become warmer and wetter during the summer season in the future, which in turn influences the environment. Additional works should be done to know the impact of land use and land cover alteration on the catchment towards sustainable development nowadays and in the future. Further studies should be done using other GCMs with state-of-the-art datasets to investigate the impact of climate change and land use–land cover on Megech hydrological process.