An optimization model for integrated water allocation in the parallel system of Segawe regulating weir and Wonorejo multipurpose dam, Tulungagung, East Java

Abstract

The parallel system of Segawe Regulating Weir and Wonorejo Multipurpose Dam is one of waterworks in the Brantas river basin. Segawe Regulating Weir was built to divert its local inflow into Wonorejo Reservoir as well as to release certain amounts of water downstream needed for ecosystem maintenance and irrigation. On the other hand, Wonorejo Multipurpose Dam was built to serve for ecosystem maintenance, irrigation, domestic water supply and electricity generation. This research discusses an optimization model that integrates the purposes of the two river structures based on the release-demand ratio and by considering the priority constraints. The optimization model was used to derive the operating pattern under requirement for the initial condition of Wonorejo Reservoir in the first period must be the same as the final condition in the last period. The results show that the reliabilities of Segawe Regulating Weir and Wonorejo Multipurpose Dam for all the purposes can reach 100% in dry, normal and wet years, where the potential energies are 20.33, 22.45 and 24.16 GWh, respectively. However, the results come with some trade-offs in the release capability of each river structure due to the integration concept.