Hydraulic Design of Labyrinth Weirs

Labyrinth weirs are widely used in spillway rehabilitation to upgrade existing dams to meet updated spillway design flood criteria.  In addition to increasing discharge capacity, these weirs are also well suited to regulating upstream pool elevations for flood control or at intake structures.  The hydraulic design of a labyrinth spillway requires the consideration of complex flow characteristics and optimization of multiple geometric parameters in an iterative process.  In addition to maximizing hydraulic performance, other considerations must be taken into account (e.g., site characteristics, construction costs, and operational objectives and requirements) when designing a labyrinth weir control structure.

During the past 10 years, considerable research has been performed at Utah State University on the hydraulics of labyrinth weirs.  This webinar presents the application of the resulting design methodology, information, and guidance used to develop effective labyrinth spillway designs.  Technical components include the influence of labyrinth weir geometry (sidewall angle and crest shape) on discharge efficiency, in-channel and reservoir-specific labyrinth weir applications, nappe interference, nappe behaviors, tailwater submergence effects, staged labyrinth weir hydraulics, high headwater ratios, downstream residual energy, generalized spillway construction costs, and a comparison between labyrinth spillways and a similar spillway type: the piano key weir.