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Flow Features for Fishway Design

Author(s): Oscar Link; Anita Laborde; Evelyn Habit

Linked Author(s): Oscar Link

Keywords: No Keywords

Abstract: Current practices in fishway design consider roughness and geometric elements into the fishway, such as brushes, arrays of boulders, baffles, and slots, to provide a more diverse flow than the so-called open channel flow, expecting to favor fishways passage. Taxonomically specific fish passes have been developed that utilize distinct physical and behavioural adaptations, such as those for eel that rely on the ability of eels to climb slopes using surface irregularities. As such, numerous substrate types have been developed to facilitate this behaviour. However, existing design guidelines only provide recommendations in terms of lumped parameters representing the bulk properties of the flow, such as the mean velocity, the turbulent kinetic energy, and the head losses at the fishway entrance. In this paper we provide insight into fundamental hydraulic features of the flow in a fishway, linking them with the expected behavior of fishes with different swimming abilities according to their sensory systems including the complex lateral line. We distinguish between sub and supercritical flows, as well as between hydraulically smooth, transitional, and rough bottom walls, and analyze wakes behind obstacles like cylinders, boulders, and baffles, as well as corner vortices such as the horseshoe vortex, and the roller in a hydraulic jump. Based on laboratory experiments, we show how these hydraulic features can be used to motivate, help, and improve fishway passage.


Year: 2018

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