Effects of ramp width variation on the hydraulic conditions of spillway that affect downstream migrating fish

Abstract An experimental investigation was conducted to elucidate the effects of a 45º upstream spillway ramp with varying spanwise width ratios (10%, 25%, 50%) on the turbulent flow characteristics used to guide fish downstream. A particle image velocimetry system was employed to acquire the veloci...

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Main Authors: Seyed Sobhan Aleyasin, Sedem Kumahor, Mark Francis Tachie, Christos Katopodis, Haitham Ghamry
Format: Article
Language:English
Published: Nature Portfolio 2025-03-01
Series:Scientific Reports
Subjects:
Online Access:https://doi.org/10.1038/s41598-025-91651-3
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author Seyed Sobhan Aleyasin
Sedem Kumahor
Mark Francis Tachie
Christos Katopodis
Haitham Ghamry
author_facet Seyed Sobhan Aleyasin
Sedem Kumahor
Mark Francis Tachie
Christos Katopodis
Haitham Ghamry
author_sort Seyed Sobhan Aleyasin
collection DOAJ
description Abstract An experimental investigation was conducted to elucidate the effects of a 45º upstream spillway ramp with varying spanwise width ratios (10%, 25%, 50%) on the turbulent flow characteristics used to guide fish downstream. A particle image velocimetry system was employed to acquire the velocity field in several vertical and spanwise planes and analyze various statistics including mean velocities, spatial velocity gradient, Reynolds stresses and turbulent kinetic energy. The results indicate that the flow topology depends significantly on the ramp width ratio. However, regardless of the width ratio, a recirculation region was observed near the foot of the spillway and a smaller one formed upstream of the ramp. For the 10% ramp width ratio, the smaller recirculation bubble accompanied by the lower velocity, spatial velocity gradient and turbulent kinetic energy along the test channel generate a more favorable pathway for downstream migrating fish. Although a partial-width ramp (i.e., 10% width ratio) is less costly and easier to retrofit compared to a full-width ramp, it creates some spanwise inhomogeneity which may impact the migration route and time of some fish species, particularly those that swim close to the riverbed.
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spelling doaj-art-ef0da32518a747ac81a0fea53eb578d82025-08-20T02:52:16ZengNature PortfolioScientific Reports2045-23222025-03-0115111410.1038/s41598-025-91651-3Effects of ramp width variation on the hydraulic conditions of spillway that affect downstream migrating fishSeyed Sobhan Aleyasin0Sedem Kumahor1Mark Francis Tachie2Christos Katopodis3Haitham Ghamry4Department of Mechanical Engineering, University of ManitobaDepartment of Mechanical Engineering, University of ManitobaDepartment of Mechanical Engineering, University of ManitobaKatopodis Ecohydraulics Ltd.Fisheries and Oceans CanadaAbstract An experimental investigation was conducted to elucidate the effects of a 45º upstream spillway ramp with varying spanwise width ratios (10%, 25%, 50%) on the turbulent flow characteristics used to guide fish downstream. A particle image velocimetry system was employed to acquire the velocity field in several vertical and spanwise planes and analyze various statistics including mean velocities, spatial velocity gradient, Reynolds stresses and turbulent kinetic energy. The results indicate that the flow topology depends significantly on the ramp width ratio. However, regardless of the width ratio, a recirculation region was observed near the foot of the spillway and a smaller one formed upstream of the ramp. For the 10% ramp width ratio, the smaller recirculation bubble accompanied by the lower velocity, spatial velocity gradient and turbulent kinetic energy along the test channel generate a more favorable pathway for downstream migrating fish. Although a partial-width ramp (i.e., 10% width ratio) is less costly and easier to retrofit compared to a full-width ramp, it creates some spanwise inhomogeneity which may impact the migration route and time of some fish species, particularly those that swim close to the riverbed.https://doi.org/10.1038/s41598-025-91651-3Modified spillwayTurbulent kinetic energy (TKE)Spanwise inhomogeneityRecirculation bubbleParticle image velocimetry
spellingShingle Seyed Sobhan Aleyasin
Sedem Kumahor
Mark Francis Tachie
Christos Katopodis
Haitham Ghamry
Effects of ramp width variation on the hydraulic conditions of spillway that affect downstream migrating fish
Scientific Reports
Modified spillway
Turbulent kinetic energy (TKE)
Spanwise inhomogeneity
Recirculation bubble
Particle image velocimetry
title Effects of ramp width variation on the hydraulic conditions of spillway that affect downstream migrating fish
title_full Effects of ramp width variation on the hydraulic conditions of spillway that affect downstream migrating fish
title_fullStr Effects of ramp width variation on the hydraulic conditions of spillway that affect downstream migrating fish
title_full_unstemmed Effects of ramp width variation on the hydraulic conditions of spillway that affect downstream migrating fish
title_short Effects of ramp width variation on the hydraulic conditions of spillway that affect downstream migrating fish
title_sort effects of ramp width variation on the hydraulic conditions of spillway that affect downstream migrating fish
topic Modified spillway
Turbulent kinetic energy (TKE)
Spanwise inhomogeneity
Recirculation bubble
Particle image velocimetry
url https://doi.org/10.1038/s41598-025-91651-3
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