Author(s): Paul Victor Villard; Andre-Marcel Baril

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Abstract: Vortex rock weirs are design elements that mimic naturally-forming cascades and are used for erosion control and habitat restoration within degraded watercourses, and as nature-like fishways to encourage fish passage. Most studies describing the hydraulics of these structures have relied on steady state simulations using computational fluid dynamics or physical based models in laboratory settings. The hydraulic evaluation of these structures in urban watercourses, where they are increasingly being implemented, is scarce. These watercourses are characterized by flow regimes consisting of prolonged periods of low flow and short duration, high intensity events. As such, determining fish passage during low-flow events may be sufficient in predicting a resident fishes ability for upstream migration. Here, the hydraulics associated with these features is examined during low-flow conditions through field measurements over installed vortex rock weirs within urban watercourses and assessed with simple models through the lens of facilitating fish passage. Specifically, the impact of different boulder configurations on fish passage and the ability for gap flow hydraulics (flow between boulders) to be modeled using simple equations to determine fish passage at vortex rock weirs during low flow is investigated.

DOI:

Year: 2018