Sediment management strategies for sustainable reservoir

The worldwide sediment management techniques consist of three basic strategies: sediment yield reduction, sediment routing, and sediment removal. The paper focuses on reservoir sustainability by considering the following points. One is how we should choose suitable sediment management options under the consideration of each sedimentation conditions. In that case, annual water and sediment inflow volumes comparing to reservoir storage volumes are the key factors for the selection. The other is how we can design suitable volumes to be discharged from reservoirs. Combination of excavation and sediment replenishment option is now becoming common in Japan. Recently these projects are still in trial stage with limited percentages of sediment replenishment ranging between 0.1 to 10% of annual reservoir sedimentation. Case study at Nunome dam is a good example of comprehensive sediment management and it contributes positively to rebuilt sand bars, mitigate the armouring of river bed, and management of reservoir sedimentation.