Assessment of the impact of climate change on future hydropower production from Koka Reservoir under two representative concentration pathways (RCP) emission scenarios

Abstract

The aim of this research is to evaluate the impact of climate change on future hydropower generation in Upper Awash River Basin, Ethiopia. In analogous manner as professionals in the science of climate change try to project future climate variables based on the past and current situation of climate pattern, it is important that future hydropower energy is also projected as it is directly dependent on precipitation, one of the most important climate variables. This enables the planners, researchers, related professionals, and policy makers to implement reasonable policies to mitigate the adverse and negative effects of climate change on energy sector, as there is no sector which does not need energy in one way or another. Two scenarios of hydropower generation were developed based on two scenarios of climate change among others, namely RCP4.5 and RCP8.5, formulated by IPCC in the fifth assessment report, AR5. RCP4.5 is one of the two stabilisation scenarios. RCP8.5 represents the business as usual scenario and that there is no policy for alleviating the harsh effect of climate change. This certainly calls for special attention of the world community. It is considered reasonable to relate the projection of climate change with future hydropower production. The three periods selected for future hydropower projection for this study were 2019–2040, 2041–2070, and 2071–2100. The reference period (2006–2014) on which the projections are based is the time period for which monthly and annual hydropower production data are available. The water evaluation and planning was used to model hydropower production and related hydrological variables. As to RCP4.5 scenario, though variable, it was seen that there will be an increase in energy production in all the three periods as compared to the reference period. The increase in energy for the periods 2019–2040, 2041–2070, and 2071–2100 was predicted to be, respectively, 7.6%, 1.5%, and 0.9%. However, as can be seen from the percentages, the increment itself has a decreasing tendency going further in the future even for this middle concentration scenario. The result of simulation under RCP8.5 scenario revealed that there will be a decrease in energy by 15.1% in the last 2 decades of the twenty-first century. This would require big effort to compensate for the resulting problems.