Economic Analysis of Reservoir Sedimentation In Gavins Point Dam

Extending a dam’s life requires adopting a new design and operational paradigm that focuses on managing the reservoir and watershed system to bring sediment inflow and outflow into balance by including reservoir sediment management facilities in dam and reservoir. However, the cost of methods that remove the sediment from reservoirs is usually prohibitive and is a serious factor preventing sustainable sediment management. Traditionally, reservoirs are designed for a lifetime of 50 to 100 years. Moreover, economic analyses omitted critical costs associated with reservoir sedimentation, such as up-and downstream damages, degrading water supply benefits, and dam decommissioning, which produce non-sustainable projects. This paper considered a case study, Gavins Point Dam, to investigate relative performance of without and with sediment management (flushing, dredging) in next 150 years, considering comprehensive sedimentation costs including prevented up-and downstream sedimentation costs. The purpose is to determine how sediment management can be effective to extend reservoir life and whether this management is economically viable. The paper applies Reservoir Sedimentation Economics Model to evaluate the benefits and costs of continued sedimentation and eventual dam decommissioning to sediment management costs and benefits. The results are compared to the sediment management plan done by the Omaha District of the U.S. Army corps of Engineers.