Detail Abstract

Hydrodynamic modelling of Magat Dam and Reservoir during extreme conditions using Telemac 2D

Abstract

Dams and reservoirs have become useful tools in managing existing water resources and have opened the possibility to effectively utilize them for irrigation, power generation and disaster mitigation. However, as to be expected when the natural course of a river is altered, these reservoirs are exposed to degradation and loss of effective operation due to natural sedimentation. In the case of Magat dam and reservoir, an improper or even the lack of sediment management at all would inevitably lead to the obstruction of the intake pipes and discontinued operation of the Magat Hydroelectric Power Plant. Moreover, the expected significant storage capacity loss will also indefinitely affect the agricultural production under the areas serviced by the said reservoir. This is in addition to the communities that depend on the reservoir for their domestic uses.</br>   Based on the accumulated sediment volume for the past five (5) years, the remaining storage capacity for the Magat Reservoir is now at around 577.68 MCM. with 30.52 MCM and 547.17 MCM for the dead and active storage capacities, respectively. With these data, the reservoir can now only hold approximately 570 MCM of water and is only expected to get worse if no effective sediment management is employed. The Telemac 2D solves the Saint-Venant or shallow water equations and was used to conduct modeling that provides the water depth and the average vertical velocity at each point of the resolution mesh. In terms of outflow volume, the calibration results for the Typhoon Ulysses showed a close agreement between the simulated and actual observed flows. On the other hand, free surface calibration results showed a very close curve and trends between the observed and simulated free surface values. The TELEMAC 2D model can now be used to estimate the impacts of parameters changes on hydrodynamic processes in Magat Dam.