Effectiveness of horizontally and vertically oriented wedge-wire screens to guide downstream moving juvenile chub (Squalius cephalus)

Bie, Jasper de; Peirson, Graeme; Kemp, Paul S.

doi:10.1016/j.ecoleng.2018.07.038

Cited by 10 publications

(13 citation statements)

References 41 publications

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“…At prototype HPPs with varying approach flow directions (e.g., during periods with and without spillway discharge), HBRs will lead to similar downstream velocity fields, whereas they can significantly change for angled bar racks with vertical bars. De Bie et al [11] investigated HBRs with wedge-wire bars for α = 30 • . The velocity measured 5 cm above the channel bottom increased by ≈50% from the rack head to the rack end for approach flow velocities of U o = 0.17 and 0.40 m s −1 .…”

Section: Comparison With Literaturementioning

confidence: 99%

“…However, the present investigation focused on a sectional model, where the bypass was not replicated. In contrast, an unregulated bypass, covering 10% of the channel width, was included in the physical model of de Bie et al [11]. They did not quantify the bypass discharge, but it can be assumed to be considerably above 10% due to the flow resistance of the fine-spaced HBR.…”

Section: Comparison With Literaturementioning

confidence: 99%

“…The transversal velocity components upstream of the rack were small, and the flow slightly accelerated along the rack. De Bie et al [11] investigated racks with α = 30 • made of horizontally and vertically aligned wedge-wire bars (s b = 6 mm, t b = 3 mm, BR ≈ 0.33 without accounting for the vertical tie-bars) in a laboratory flume for two different discharges.…”

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confidence: 99%

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Velocity Fields at Horizontal Bar Racks as Fish Guidance Structures

Meister

Fuchs

Beck

et al. 2020

Water

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Horizontal bar racks used as fish protection measures at hydropower plants have rapidly gained importance in recent years. Despite the large number of installed racks in Europe, systematic investigations of the hydraulic losses and velocity fields were missing. To fill these research gaps, the hydraulic performance of horizontal bar racks was systematically investigated in a laboratory flume for a large number of rack parameters and different hydropower plant layouts. The results of the head loss assessment are published in a paper entitled Head Losses of Horizontal Bar Racks as Fish Guidance Structures, whereas the present paper focuses on the velocity fields. The measurements show that the bar shape, the horizontal approach flow angle, and the clear bar spacing have only a minor effect on the velocity fields. In contrast, bottom and top overlays might enhance the fish guidance efficiency for bottom and surface oriented fish, while the asymmetric downstream velocity field can reduce turbine efficiencies. The hydropower plant layout strongly affects the approach flow field to horizontal bar racks. For block-type hydropower plants, the installation of a dividing pier or partial opening of the spillways improves the flow field for better fish guidance.

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Section: Comparison With Literaturementioning

confidence: 99%

Section: Comparison With Literaturementioning

confidence: 99%

mentioning

confidence: 99%

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Velocity Fields at Horizontal Bar Racks as Fish Guidance Structures

Meister

Fuchs

Beck

et al. 2020

Water

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“…(1) by hydraulics and biological responses created by the structure holding the screens (nose cone of CGS's cylindrical T-screen) and (2) hydraulics and biological responses at the fish-water separation surface such as traditional passive mesh screens, bar racks (Albayrak et al 2020a(Albayrak et al , 2020b, trash racks (Raynal et al 2013), curved bars (Beck et al 2020), louvers (Albayrak et al 2018), and flat-plate wedgewire screens (de Bie et al 2018) whether placed perpendicular to flow or angled. Cylindrical screens placed with the axis perpendicular to flow, such as tested by Weisberg, et al (1987), are also in the second category.…”

Section: Discussionmentioning

confidence: 99%

Why cylindrical screens in the Columbia River (USA) entrain few fish

Coutant¹

2021

Journal of Ecohydraulics

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Cooling-water intakes often entrain large numbers of larval and juvenile fish, leading to questions why a water intake on the Columbia River, USA, with axial flow, cylindrical screens on a T-screen structure entrained very few (four fish in 4,007 x 10 3 m 3 of water sampled over four years). This is despite being downstream of spawning areas for Chinook salmon Oncorhynchus tshawytscha releasing up to 56 million pre-smolts and having screens consisting of porous plate with 9.5-mm-diameter pores capable of passing salmon fry and other small fish (poor physical exclusion). Multiple publications of experiments and observations in hydraulics and biology are used to help explain the low entrainment, concluding that effects of the screening structure rather than the actual screen are most important. Primary mechanisms appear to be: (1) bow-wave-like hydraulics at the structure's nose cone that deflect small fish away from the screen's pores, and (2) fish detection and avoidance of pressure and velocity changes upstream of the structure that aid deflection. These combined hydraulic and biological-behavior effects of the structure would cause salmon fry and other small fish to bypass the screened portion of the intake. At the screens, (3) high ratio of sweeping flow to approach and through-screen velocities likely further prevents entrainment. Although site-and design-dependent, this analysis may be useful for evaluating or planning other screen installations and focusing regulatory attention on hydraulics of the structure as well as the screen.

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“…Because the fish cannot pass through the gaps and smolts generally avoid both the structures and the resulting turbulence (Enders et al, 2012;Nestler et al, 2008;Williams et al, 2012), they may migrate along the angled boom to reach the southern flow towards the gates. It has been shown that fish guidance systems such as fish-friendly trash-racks or trash-booms placed upstream of the intake are viable solutions to guide fish away from HPP intakes (Albayrak et al, 2018;Boes et al, 2016;Calles et al, 2013;de Bie, Peirson, & Kemp, 2018;Nestler et al, 2008;Tomanova et al, 2018). In particular, Nyqvist et al (2017), who analysed migration data from a very similar angled rack with horizontal bars, documented high guiding effectively for salmon towards the bypass channel at a HPP dam and intake facility in Sweden but with a full depth rack.…”

Section: Discussionmentioning

confidence: 99%

Modelling mitigation measures for smolt migration at dammed river sections

et al. 2019

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There is no generic solution to establish safe passage of downstream‐migrating fish passed hydropower facilities, and mitigation measures are species and site specific. Development of solutions is thus often based on “trial and error,” and modelling‐based approaches may significantly reduce cost and time to arrive at successful mitigation. Here, we explore such an approach by combining data on fish migration and hydraulic modelling. First, we performed a positional telemetry study at a dammed section of a Norwegian river, where 100 Atlantic salmon smolts were tagged to track their downstream movement at the vicinity of a hydropower intake channel and bypass gates. An explanatory model was developed to explore mechanisms of migration route, into the intake towards the turbines or through the bypass gates. Next, flow conditions during the smolt run was numerically modelled to explore the physical environment of the tracked smolts. The joint results from the two approaches supported the general assumption that downstream migration is strongly influenced by flow patterns and showed that fish entering the study site closer to the riverbank where the intake channel is located were more likely to enter the intake due to the strong currents towards the intake. Finally, a suite of measures to guide salmon smolts past the hydropower intake were proposed based on the findings and local conditions and tested by hydraulic modelling. We found that most of the measures that were likely candidates for field trials would most likely fail at improving safe passage, and only a rack‐type guiding boom was promising. The presented combination of telemetry migration data and hydraulic modelling illustrates the value of evaluation of mitigation measures prior to implementation.

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Effectiveness of horizontally and vertically oriented wedge-wire screens to guide downstream moving juvenile chub (Squalius cephalus)

Cited by 10 publications

References 41 publications

Velocity Fields at Horizontal Bar Racks as Fish Guidance Structures

Velocity Fields at Horizontal Bar Racks as Fish Guidance Structures

Why cylindrical screens in the Columbia River (USA) entrain few fish

Modelling mitigation measures for smolt migration at dammed river sections

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