Page - 134 - in Book of Full Papers - Symposium Hydro Engineering

were also critical to improve the hydraulic performance of the restored spillway chute.  Simulation of behavior of flow over the Emergency Spillway’s monoliths/weir and down the Emergency Spillway hill slope. Information from this analysis informed designs about the type and extent of protection needed downstream, and methods to increase the factor of safety of the concrete monoliths without adversely impacting the outflow capacity. The complex hydraulics of the project, the immediate data needs of other teams (structure, geotechnical, and geological), compliance with the current codes and design guidelines, concurrence by regulating agencies (FERC and DSOD), and the available time were some of the challenges faced by the hydraulic engineering team. To meet the project objectives, the team agreed that: (1) initial hydraulic analyses would be done using simplified one-dimensional (1-D) and two- dimensional (2-D) numerical models, with the resulting data passed to other teams; (2) for selected alternatives, the findings from the simplified 1-D and 2-D models would be verified with three-dimensional (3-D) numerical models; and (3) a 1:50 scaled physical model of the FCO Spillway chute would be developed to validate the findings from the numerical models. Table 2 summarizes the hydraulic engineering analyses completed and the methods used. Table 2 Hydraulic Models Used in the Restoration of Oroville Dam’s Spillways Feature Analyzed Model Type Modeling Objective FCO Spillway Chute 1-D models  Determine flow characteristics (flow depth, velocity, drag force, uplift forces, cavitation index, centrifugal forces, boundary layer thickness, and air content) along the spillway chute profile.  Inform design decisions by structural, geotechnical, and geological engineers, and construction managers regarding best design features and methods of construction. 134