Flow Through Rockfill Dam

Occurrence of an extraordinary flood caused large flows through the uncompleted rockfill section of Hell Hole Dam on the Rubicon River, California. The partially completed dam was then acting as a cofferdam for the construction and ultimately failed during flow through the rockfill portion. During the flood, observations were made of the reservoir elevations at certain times, and also on two occasions of the elevations at which flow was issuing from the downstream face of the rockfill. Based on the flood hydrograph, computed flow through the diversion tunnel, and the mentioned observations, flows through the rockfill were computed and the equation for nonlinear flow was determined. Results suggest that flow through rockfill can be computed assuming laminar flow, even though flow is not laminar. Comparison is made with published results obtained for flow through rockfill by use of models.