Innovative reregulation weirs for dam releases

In this paper two different reregulation weir designs for dam release improvement are discussed. A porous timber crib is favored for applications where increased minimum flow is needed, and a labyrinth with vertical walls is favored where both minimum flow and aeration are needed. Weirs constructed below hydropower dams can improve minimum flows between generating periods and increase tailwater dissolved oxygen (DO) content during generation. TVA has developed two distinct functional designs: a timber crib weir for minimum flow and a labyrinth weir for minimum flow and aeration. A target minimum flow is sustained by slow drainage of the weir pool between periodic refills. With the labyrinth weir, aeration occurs during generation via overtopping. Both weirs are designed to maximize the value of the tailwater while minimizing backwater on the upstream turbine, unsafe hydraulic conditions, and environmental disturbance