Optimal Reservoir Operations on Water Resource Projects At Wabi Shebelle River Basin

No Thumbnail Available



Journal Title

Journal ISSN

Volume Title


Addis Ababa University


Wabi Shebelle River Basin is one of the twelve river basins in Ethiopia with catchment area of 202,697 Km2 and covering parts of the regions Oromia, Harari, Somali and a small area at the source of the Wabe River in SNNPE. Wabi Shebelle river basin has an estimated potential irrigable land of 237,905 and hydropower potential of 5,440 GWh/year is expected to contribute about 3.48% of the total estimated potential of the country. In this study, HEC-ResSim (Hydrologic Engineering Center-Reservoir System Simulation) model was used to simulate reservoirs operation to optimize water for hydropower energy production, flood management as well as environmental flows. To control the model, two scenarios were simulated via scenario one (Baseline Scenario) and scenario two (future development scenario) based the project implementation period to incorporate the parameters that may influence flow requirements at a reservoir include hydrology conditions and simultaneous operation by other reservoirs in a system. The model was attempted to represent the physical behavior of reservoirs in the basin with its hydrologic routing to represent the lag and attenuation of flows through the main and tributaries of the river. Hence, the model results suggest that the new reservoir operation rule selected, and its reservoir and power guide curves established for modeling of the dams and reservoirs operation enhances average energy production of the plant by 13% and also the study evaluate the effect of Erer and Gololcha irrigation project on Gode, results reveal that the new operation system will decrease water availability in the dry season by 4.07 and decrease flooding in the wet season by 9.5%. Overall the study has determined the new reservoir operation system will evenly allocate and release the available water in real time during day-to-day and emergency operations throughout the year.



water resource, Wabi Shebelle river basin, Optimal Reservoir