Optimal Operation of Cascade Reservoir Systems under Climate Change: Case Study of Tekeze Hydropower Reservoir in the Tributary of the Blue Nile River

Abstract

Planning and optimal operation of reservoirs under the paradigm of climate change is one of the most momentous problems in the planning and management of water resources due to the rapid growth of economy and population. In this study, Soil and Water Assessment Tool (SWAT) and reservoir operation optimization (HEC-ResPRM) models have been employed in the three cascade hydropower reservoirs in Tekeze basin, Ethiopia to investigate the impact of planned cascade reservoirs’ operation on the existing reservoir on the face of climate change. Results showed that an increase in rainfall and temperature in the future will be critical to future inflow in cascade hydropower reservoirs, with rainfall variability having a greater impact than temperature variability. HEC-ResPRM was prepared to reproduce optimum hydropower reservoir storage and water levels on the joint cascade operation of Tekeze reservoirs in each mode under climate change effect. Joint optimum operation of cascade reservoirs in different operation modes under climate change in both RCP4.5 and RCP8.5 climate scenarios affects existing reservoir operation in the future. Therefore, it is better to improve existing reservoir operation before investing into new planned cascade reservoirs and incorporate climate change scenarios in the planning, design, and operation of new reservoirs in Tekeze Basin. The results of this study can help the water resources planners and managers to plan and manage the future water resources of Ethiopian Rivers.