Gravel Capping for Turbidity Control during Sediment Sluicing Upstream of Oouchibaru Dam by the Use of Ejector Pump System

Tsurusaki, D, Kiyota, M, Asazaki, K, Nakamura, Y, Temmyo, T, Mizunuma, M, Mousa, A, Kantoush, S, Sumi, T, 37th IAHR World Congress, Kuala Lumpur, Malaysia 13-18 August 2017, 2017

Successful control of sediment sluicing for river and dam systems requires adopting integrated management plans. Minimizing sediment flow at an early stage is, therefore, important for efficient sediment sluicing as the resuspension of silty sediment could be extremely detrimental to the downstream environment. Gravel capping is one of the common countermeasures that are used effectively for turbidity control during sluicing process. It involves forming a layer of gravel and sand over the silt deposited at the bottom of the reservoir to minimize its resuspension and subsequent flow to the downstream reaches below dam. In this study, a hopper-type of an ejector system is used to execute capping in the reservoir of Oouchibaru dam in Japan. Trial experiments have first been carried out coupled with field investigation of the system design and performance for comparison and gauging efficiency of the implementation. The outcomes of the study are used to propose a final layout plan to effectively carry out sluicing operation. The Mimi River Basin Integrated Sediment Flow Management Plan is presented as a success story for gravel capping by the use of the Ejector system. In this project, a total volume of 107,600 m3 of gravel and sand is projected, of which approximately 28,200 m3 of gravel capping has been completed by monitoring water turbidity in 2016.

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