Author(s): Mitsumasa Anan, Kozue Yuge, Kosuke Hamada
Linked Author(s): Mitsumasa Anan
Keywords: Flood control, irrigation facility, surface water track, river modelling, unsteady flow
Abstract: Prompt gate control of diversion weirs is required to flow the excess water under the flood condition. It is also important for gate opening method of diversion weir to ensure safety and simplicity to prevent the water accidents and human errors. The aims of this study are evaluating the effect of gate opening of a series of diversion weirs on the temporal and spatial fluctuations of river water level and optimizing the gate opening operation for disaster prevention under the flood condition. A simulation model describing one dimensional unsteady flow is introduced to evaluate the effect of the gate opening of multiple diversion weirs on the downstream current in the Onga River. Using this model, the spatial and temporal variations of the river water level are clarified under the different patterns of gate opening operation. To evaluate the influence that the fall dawn time for weir affects the change of water level, river water level simulations are calculated for six observed floods. As the result of river water level calculated using unsteady flow model, it is recognized that the fall down time for the weir are related to the change of the river water level closely. In particular, the fluctuation of water level and extent of impact by gate opening varies with the speed of the gate opening. The appropriate speed of the gate opening is clarified to reduce the fluctuation of water level by gate opening under the flood condition. The method introduced in this study is effective to develop the optimal gate control method of the diversion weirs for not only prompt flood protection but also safety
Year: 2017