JDR Vol.13 No.4 pp. 702-708
doi: 10.20965/jdr.2018.p0702


Planning and Analysis of Sedimentation Countermeasures in Hydropower Dams Considering Properties of Reservoir Sedimentation

Chihaya Onda*,†, Tetsuya Sumi**, and Tsuyoshi Asahi***

*West Regional Headquarters, Electric Power Development Co., Ltd.
6-2-27 Nakanoshima, Kita-ku, Osaka-shi, Osaka 530-0005, Japan

Corresponding author

**Water Resources Center, Socio and Eco Environment Risk Management, Disaster Prevention Research Institute, Kyoto University, Kyoto, Japan

***Hydropower Department, Electric Power Development Co., Ltd., Tokyo, Japan

April 27, 2018
May 10, 2018
August 1, 2018
reservoir sedimentation, hydropower, sedimentation sluicing, dam operation

Sedimentation in hydropower reservoirs is one of the most important problems facing power generation. Many of the reservoirs our company’s dams, built in the postwar reconstruction period, have been storing up sedimentation for decades. The percentage of sedimentation is now considerable, about 9%, because of a combination of a high degree of sediment production and the river flow regime. We have been trying to excavate the sedimentation from the reservoirs to avoid aggradations of upstream riverbeds and to eliminate obstacles to intake and outlet functions. Considering sediment properties, we have carried out representative five different ways of managing reservoir sediment. At the Sakuma dam, which is comparatively large, provisional transporting inside the reservoir is the main countermeasure, but radical management will be required in the near future. At the Futatsuno dam and Taki dam, which are medium-sized, the current volume of sedimentation excavation is not sufficient to maintain the size of the reservoir, due to flow sedimentation. Sediment routing methods, such as bypassing, will therefore be urgently planned. At the Setoishi and Yambara dams, the testing of sediment sluicing or hydro-suction sediment removal systems has already started. Regarding sedimentation sluicing, we have studied the feasibility of sediment bypass tunnels and gated outlets in the dam reservoir that is unsuitable for sluicing with the existing spillway. We found that gated outlet will be effective. Although there are no quick remedies that can reduce reservoir sedimentation dramatically, there are some methods that may be suitable, considering the size, life and basin of each reservoir. Not only the technical feasibility, but also the economic advantages and ecological acceptability should be considered. To sustain reservoirs and hydropower, sedimentation should be managed effectively and adaptively, based on the specific conditions of each reservoir.

Cite this article as:
C. Onda, T. Sumi, and T. Asahi, “Planning and Analysis of Sedimentation Countermeasures in Hydropower Dams Considering Properties of Reservoir Sedimentation,” J. Disaster Res., Vol.13 No.4, pp. 702-708, 2018.
Data files:
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