ABSTRACT
A sustainable water management system requires the reservoir operation that maintains the environmental flow (e-flow) for ecosystem integrity while optimizing the power production. Yeywa hydropower reservoir is operated to generate the power considering the e-flow requirement for the target of hydro-balancing. HEC-ResSim model is used to simulate the reservoir system with alternative e-flow constraints. To evaluate the possible impact of hydrologic alteration due to reservoir operation, Range of Variability Analysis (RVA) is used. When the reservoir is operated to generate the power maintaining the minimum amount of e-flow, the flow regime alteration reduces while increasing the annual power production compared to the existing operation rule. And, this operation can generate the enough power in each month without power deficit. When the reservoir is operated to generate the power by maintaining the five e-flow components, it can provide the better result for the riverine ecosystem in terms of the more decreased hydrologic alteration. But energy generation has an impact of power deficit in the non-rainfall period although the power production increases significantly in the rainy season. The result indicates that the operation with minimum e-flow constraint makes the better performance to be trade-off for the controversy between the different water users.
