Sediment impacts from the Savage Rapids Dam removal, Rogue River, Oregon

摘要

Before a dam removal project is implemented, engineers are often asked to estimate the potential for impacts from the release of reservoir sediment. Field measurements, numerical models, and physical models are typically used to develop sediment impact estimates. This information helps decision makers to make informed decisions about when and how to remove the dam, whether to allow the river to erode the reservoir sediment, or to remove or stabilize the reservoir sediment prior to dam removal, or whether mitigation of the effects is needed. Although numerous dams have been removed, mostly small in size, few case studies on sediment impacts have been documented. Because there are limited case studies, dam removal regulators and stakeholders often err on the side of caution when selecting the level of preremoval analysis or determining whether the reservoir sediment needs to be removed prior to dam removal. The purpose of this paper is to increase our knowledge base for application to future dam removals. The chapter discusses sediment impacts associated with the removal of the 11.9-m-high Savage Rapids Dam on the Rogue River near Grants Pass, Oregon. A unique factor to the Savage Rapids project was the construction and operation of a new diversion facility and water intake located immediately downstream of the dam, which introduced additional consequences associated with the release of reservoir sediment.