Reservoir sedimentation affects all Reclamation reservoirs to some extent. In some cases reservoir sediment is beginning to approach the intake elevation for either a penstock or water diversion. A gated intake at a lower elevation can be used to remove sediment in the vicinity of the gate and prevent sediment from entering the penstock or water diversion. Can we construct numerical models to assist in the design and operation of these low level outlets? Many Reclamation facilities are approaching an age of 100 years. Often, the intake elevation for penstocks leading to hydroelectric facilities was set at the elevation expected after 100 years of sedimentation. Our current numerical modeling tools are lacking in their ability to simulate pressure flushing as may occur at facilities where they are attempting to keep the penstock intake clear of sediment by flushing sediment at a lower level intake while keeping the reservoir nearly full. Our current sediment models can only model flushing of sediment when the reservoir is drawdown completely and there is not appreciable reservoir pool left. Therefore, to design appropriate low level outlets and to analyze various operations, it will be necessary to have a numerical model that can simulate this process.
