A Physical and Behavioral Barrier for Enhancing Fish Downstream Migration at Hydropower Dams: The Flexible FishProtector

Tutzer, Ruben; Röck, Simon; Walde, Janette; Haug, Jonas; Brinkmeier, Barbara; Aufleger, Markus; Unfer, Günther; Führer, Simon; Zeiringer, Bernhard

doi:10.3390/w14030378

Cited by 11 publications

(11 citation statements)

References 37 publications

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“…Moreover, recent studies suggest that a combination of physical barriers such as bar screens with behavioral barriers (e.g., electric fields) could increase fish protection from turbine entrainment and the guiding effect towards bypasses (cf. Tutzer et al, 2021Tutzer et al, , 2022Haug et al, 2022). However, since fish downstream movements can also take place at very low water temperatures in late autumn/ winter and reduced metabolic rates potentially increase the proportion of fish drifting passively with the main current (Wiesner et al, 2004), it would be worthwhile for future studies to investigate whether the turbine entrainment risk is increased under these conditions.…”

Section: Discussionmentioning

confidence: 99%

“…In contrast, behavioral barriers are intended to induce an avoidance or scaring reaction in fish through external stimuli such as electricity, light, sound or air bubbles (e.g., Schilt, 2007;Noatch and Suski, 2012). Recently, so-called "hybrid" barriers have also been developed, where physical barriers (e.g., bar screens) are combined with electric fields to provide an additional behavioral barrier (Tutzer et al, 2021(Tutzer et al, , 2022Haug et al, 2022).…”

Section: Introductionmentioning

confidence: 99%

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Downstream fish passage at small-scale hydropower plants: Turbine or bypass?

Knott

Mueller

Pander

et al. 2023

Front. Environ. Sci.

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Introduction: Hydropower plants are frequently equipped with physical and behavioral fish protection barriers to prevent downstream moving fish from harmful turbine passage and to guide them to alternative bypasses. As not only diadromous but also potamodromous fish species migrate and inevitably have to pass hydropower plants, knowledge on corridor usage for a wide range of species is important to identify potential deficits and to improve bypass efficiency.Methods: In this study, the corridor usage of downstream moving fish (6,646 individuals from 42 species) was investigated at four small-scale hydropower plants with different concepts to prevent turbine entrainment and to bypass fish.Results: Despite existing bypasses and fine screens with 15 mm and 20 mm bar spacing to prevent turbine entrainment, a large proportion of fish (35%–88%) still passed the turbines. The mainly poor efficiency of the investigated bypasses was probably due to low discharge and unfavorable bypass location or detectability. The various bypass types were used by a different range of fish species and sizes due to species-specific behavior and differing fish communities between sites. The effectiveness of the investigated downstream corridors was positively correlated with the share of discharge.Discussion: To reduce the negative ecological impacts of hydropower plants on downstream moving fish, well-performing bypasses are required that consider not only current requirements regarding design, dimensioning and location, but also the site-specific fish community. Thus, bypasses should function for the widest possible range of species, which can be achieved through less selective bypass types such as full-depth bypasses, or a combination of different bypass systems. Moreover, less harmful turbine technologies and more effective fish protection systems need to be implemented, since fine screens with 15 mm and 20 mm bar spacing cannot prevent small-bodied fish species and juvenile fish <20 cm from turbine entrainment.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Downstream fish passage at small-scale hydropower plants: Turbine or bypass?

Knott

Mueller

Pander

et al. 2023

Front. Environ. Sci.

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“…The bar rack was electrified with electrodes made of structural steel rods (8 mm diameter) which were attached with cable ties to the front side of the electrically disconnected bars. A Neptun pulse generator from Procom System S.A. (Poland) was used to generate the pDC of 80V, which has been proven to be effective and harmless for fish in prior studies [32,34,39]. Connection to the wiring was made with cable lugs attached by electrically conductive screws which were mounted to the upper end of the electrodes.…”

Section: Experimental Channelmentioning

confidence: 99%

“…Immobilization of the fish, especially upstream of the electric field, must be prevented to avoid passive drift towards the undesired route [20]. Factors such as voltage, pulse parameters and electrode distance have to be optimized for the current application and fish species/size to prevent taxis, narcosis or tetany, as described in the literature [30][31][32]. A pulsed direct current (pDC) allows for more controlled escape reactions of fish when compared to direct current, in addition to showing a less harmful effect on deterred fish [22,33,34].…”

Section: Introductionmentioning

confidence: 99%

Retrofitting of Existing Bar Racks with Electrodes for Fish Protection—An Experimental Study Assessing the Effectiveness for a Pilot Site

Haug

Auer

Frees

et al. 2022

Water

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Downstream-migrating fish in rivers tend to follow the main current, and are in danger of swimming through the turbines at run-of-river hydropower plants, possibly causing high mortality rates. To avoid these losses, fish must be prevented from entering the turbines. Most existing vertical bar rack systems (used for turbine protection) however usually do not ensure proper fish protection due to large bar spacings. FishProtector technology enables the retrofitting of existing bar racks (i.e., the mechanical barrier) with additional electrodes to create a hybrid barrier. The induced electric field in the water aims to create a behavioral barrier to prevent fish passage through the bar rack. In this study, ethohydraulic experiments to investigate the effect of such a behavioral barrier on fish were performed. In detail, the fish-protection rate at a bar rack with a bar spacing of 30 mm was tested in five different scenarios: (i) a bar rack without electrodes (reference), and four electrified setups with electrode spacings of (ii) 80 mm, (iii) 120 mm, (iv) 160 mm, and (v) 200 mm. A flow velocity of 0.23 m/s was chosen to replicate the situation at a planned pilot site. The study was conducted in an outdoor laboratory flume using small fish of several local riverine species, mostly cyprinids and minnows. The results show that the mean fish-protection rate in the experiments could be increased from 62% in the reference setup up to 96% in the electrified setups.

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“…In particular, these regulations apply to water intakes for cooling purposes, characterized by very high yields. Large hydropower plant intakes are also dangerous for fish, as on their way downstream, they are exposed to various related negative effects, ranging from a delay in downstream movement to being injured or killed by rotating blades [24].…”

Section: Introductionmentioning

confidence: 99%

Hydraulic Analysis of a Passive Wedge Wire Water Intake Screen for Ichthyofauna Protection

Zielina,

Pawłowska-Salach,

Kaczmarski

2023

Applied Sciences

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A passive wedge screen, thanks to its many functional and environmental advantages, has recently become a popular type of surface water intake for municipal and industrial purposes. The design solutions proposed in this paper for a passive wedge wire screen intake model and two different deflectors have been experimentally tested under conditions that can be considered as no-flow conditions at the hydraulic flume. There was only a slight flow associated with the operation of the screen, while there was almost no flow in the hydraulic channel itself, such that it would be considered a watercourse. A hydraulic analysis was carried out, including velocity distribution around the screen as well as the determination of head losses with or without deflectors installed inside the screen. Lower inlet and inflow velocities to the surface of the water intake reduce the risk of injury or death to small fish and fry as well as attracting pollutants understood as sediments, debris, and plant remains floating in the river. In order to achieve the lowest possible maximum inlet and inflow velocities at the highest possible intake capacity, it was necessary to equalize the approach velocity distributions. It was shown that by using the proposed deflectors, the approach velocity distributions were equalized and the maximum values of inflow and inlet velocities were reduced. A water intake screen with a deflector with an uneven porosity distribution equalized the approach velocities better than a deflector with equal openings, but the differences were small. Installing the wedge screen model reduced the maximum inlet velocity from exceeding 2 m/s to a value of 0.08 m/s, and after installing deflectors with equal and unequal openings to values of 0.06 m/s and 0.05 m/s, respectively. In addition to laboratory tests, the paper describes the numerical simulations performed in ANSYS Fluent software. The results of the simulations made it possible to obtain a broader study, as well as to compare the velocity values obtained at the measuring points during the laboratory tests.

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A Physical and Behavioral Barrier for Enhancing Fish Downstream Migration at Hydropower Dams: The Flexible FishProtector

Cited by 11 publications

References 37 publications

Downstream fish passage at small-scale hydropower plants: Turbine or bypass?

Downstream fish passage at small-scale hydropower plants: Turbine or bypass?

Retrofitting of Existing Bar Racks with Electrodes for Fish Protection—An Experimental Study Assessing the Effectiveness for a Pilot Site

Hydraulic Analysis of a Passive Wedge Wire Water Intake Screen for Ichthyofauna Protection

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