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Fish Passage at Hydropower Dams
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Fish Passage at Hydropower Dams

A special issue of Water (ISSN 2073-4441). This special issue belongs to the section "Hydraulics and Hydrodynamics".

Deadline for manuscript submissions: closed (31 December 2021) | Viewed by 37479

Special Issue Editors

Dr. Ismail Albayrak

E-Mail Website
Guest Editor
Laboratory of Hydraulics, Hydrology and Glaciology, ETH Zurich, 8093 Zurich, Switzerland
Interests: upstream and downstream fish migrations; hydro-abrasion at hydraulic structures; sediment bypass tunnels and turbines; reservoir sedimentation and management; suspended sediment and bed load transports in open channel flows; turbulent open-channel flows; hydraulic structures
Special Issues, Collections and Topics in MDPI journals
Prof. Dr. Laurent David

E-Mail Website
Guest Editor
Institut Pprime, CNRS- Université de Poitiers - ENSMA, UPR 3346, 11 Boulevard Marie et Pierre Curie, TSA 51124, 86073 Poitiers, CEDEX 9, France
Interests: upstream and downstream fish migration; eco-hydraulics; environmental hydrodynamics; turbulent open-channel flows; fluid–structure interaction; cohesive and non-cohesive sediment transports; rheology; renewable energy
Special Issues, Collections and Topics in MDPI journals
Dr. Ana Teixeira da Silva

E-Mail Website
Guest Editor
The Norwegian Institute for Nature Research (NINA), P.O. Box 5685 Torgard, 7485 Trondheim, Norway
Interests: upstream and downstream fish migration; ecohydraulics; fish passage engineering; ecology and fish conservation and restoration; fish physiology; fish evolution and behavior; biomechanics of fish; environmental hydrodynamics; renewable energy
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

Hydropower dams represent barriers for animal movement, in both upstream and downstream directions. For instance, fish can be blocked or delayed in their spawning migration and are subjected to injury or death when passing turbines, spillways, or bypasses in their downstream migration, resulting in cumulative negative impacts on the individual and population levels.

Fish-friendly turbines, collection systems, sensory barriers, mechanical and behavioral barriers, physical barriers, and fish-friendly operations are widely known technological concepts to mitigate negative impacts of hydropower dams by protecting and guiding downstream migrating fish. Compared to downstream fish passage technologies, upstream fish passage technologies are well advanced but still need to be adapted for multi-species of different biomechanical requirements and attraction flow at the entrance. Furthermore, the head and layout of hydropower dams require specific adaptations of the technologies. Therefore, this Special Issue focuses on both upstream and downstream fish migration research from different regions of the world and different hydropower dam layouts.

Contributions from the latest laboratory, field, and/or numerical research studies on the available or innovative new solutions, as well as tools to evaluate the effectiveness of the solutions are invited. Original research papers and critical reviews will be considered. All scales of application are accepted.

Dr. Ismail Albayrak
Prof. Dr. Laurent David
Dr. Ana Margarida Teixeira de Silva
Guest Editors

Manuscript Submission Information

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Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Water is an international peer-reviewed open access semimonthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2600 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • upstream fish passage solutions
  • downstream fish passage solutions
  • fish-friendly turbines
  • physical barriers
  • mechanical and behavioral barriers
  • sensory barriers
  • collection systems
  • bypass systems
  • flow–fish interactions
  • fish behavior

Published Papers (14 papers)

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Research

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19 pages, 941 KiB  
Article
Retrofitting of Existing Bar Racks with Electrodes for Fish Protection—An Experimental Study Assessing the Effectiveness for a Pilot Site
by Jonas Haug, Stefan Auer, Calvin Frees, Barbara Brinkmeier, Ruben Tutzer, Daniel S. Hayes and Markus Aufleger
Water 2022, 14(6), 850; https://doi.org/10.3390/w14060850 - 09 Mar 2022
Cited by 8 | Viewed by 1848
Abstract
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 [...] Read more.
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. Full article
(This article belongs to the Special Issue Fish Passage at Hydropower Dams)
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23 pages, 16013 KiB  
Article
Field Investigation of Hydraulics and Fish Guidance Efficiency of a Horizontal Bar Rack-Bypass System
by Mohammadreza Maddahi, Roland Hagenbüchli, Ricardo Mendez, Claudia Zaugg, Robert Michael Boes and Ismail Albayrak
Water 2022, 14(5), 776; https://doi.org/10.3390/w14050776 - 01 Mar 2022
Cited by 5 | Viewed by 3006
Abstract
This paper investigates the hydraulics and fish guidance efficiency of a Horizontal Bar Rack-Bypass System (HBR-BS) installed at a hydropower plant with a design discharge of 33 m3/s. The HBR is placed at a horizontal rack angle of 38° to the [...] Read more.
This paper investigates the hydraulics and fish guidance efficiency of a Horizontal Bar Rack-Bypass System (HBR-BS) installed at a hydropower plant with a design discharge of 33 m3/s. The HBR is placed at a horizontal rack angle of 38° to the flow direction with clear bar spacing of 20 mm. The BS has a vertical-axis flap gate with two openings. The HBR-BS complies with most literature design criteria. Velocity measurements were conducted using a moving-vessel Acoustic Doppler Current Profiler (ADCP). The fish monitoring study was conducted using a stow net, video, and ARIS sonar recordings. The fish monitoring calculations imply guidance efficiency of 84%, even for fish with total body lengths below 10 cm. Furthermore, the hydraulic results show that the flow field is favorable in terms of fish guidance due to a good alignment of the rack and the BS, corroborating the fish monitoring results. The results indicate that the HBR-BS functions not only as a physical barrier but also as a mechanical behavioral barrier for some small fish that are capable of physically passing the HBR. The present results are compared and discussed with the laboratory and field results from different studies in the literature. Full article
(This article belongs to the Special Issue Fish Passage at Hydropower Dams)
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12 pages, 1750 KiB  
Article
Experimental Assessment of the Influence of Fish Passage Geometry Parameters on Downstream Migrating Atlantic Salmon (Salmo salar) Smolts Behavior
by Sebastien Erpicum, Vasileios Kitsikoudis, Pierre Archambeau, Benjamin Dewals and Michel Pirotton
Water 2022, 14(4), 616; https://doi.org/10.3390/w14040616 - 17 Feb 2022
Cited by 1 | Viewed by 1588
Abstract
The fragmentation of rivers caused by the construction of dams and weirs disturbs fish migration and poses a threat to fish populations and aquatic biodiversity. Fish passages around hydraulic structures aim to restore river connectivity; however, the effective design of fish passages is [...] Read more.
The fragmentation of rivers caused by the construction of dams and weirs disturbs fish migration and poses a threat to fish populations and aquatic biodiversity. Fish passages around hydraulic structures aim to restore river connectivity; however, the effective design of fish passages is a challenging problem that depends on several processes. The present experimental study investigated how the characteristics of a trash rack at the entrance of a fish passage for downstream migration affects fish behavior and subsequently the effectiveness of the fish passage. A series of experiments was carried out to systematically analyze the behavior of Atlantic salmon smolts in a flume with two outlets featuring the same 1:1 physical model of the entrance of a downstream passage with or without a trash rack. The parameters that were tested were the spacing of the vertical round bars of the trash rack, the location of the trash rack at the fish passage, and the velocity gradient at the entrance of the passage. Aggregated results showed that only 34% of the fish selected the outlet with a trash rack to exit the flume while 66% preferred the unobstructed outlet. More fish swam through the outlet with the trash rack when the spacing of the vertical bars increased from 10 cm to 20 cm and when the rack was placed in the higher velocity region compared to the lower velocity one. These results show that a trash rack acts as an obstacle to Atlantic salmon smolts passing through a downstream passage. When possible, trash racks should be avoided at the entrance of downstream fish passages. Full article
(This article belongs to the Special Issue Fish Passage at Hydropower Dams)
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20 pages, 2712 KiB  
Article
A Physical and Behavioral Barrier for Enhancing Fish Downstream Migration at Hydropower Dams: The Flexible FishProtector
by Ruben Tutzer, Simon Röck, Janette Walde, Jonas Haug, Barbara Brinkmeier, Markus Aufleger, Günther Unfer, Simon Führer and Bernhard Zeiringer
Water 2022, 14(3), 378; https://doi.org/10.3390/w14030378 - 27 Jan 2022
Cited by 9 | Viewed by 2786
Abstract
Fish protection at hydropower plants is important for the sustainability of hosting ecosystems and the acceptance of hydropower. On their way downstream, fish are exposed to hydropower plants and various related negative effects, ranging from a delay in downstream movement to being injured [...] Read more.
Fish protection at hydropower plants is important for the sustainability of hosting ecosystems and the acceptance of hydropower. On their way downstream, fish are exposed to hydropower plants and various related negative effects, ranging from a delay in downstream movement to being injured or killed by a turbine. Understanding the behavior of fish in close proximity to protection devices is essential in order to establish efficient fish protection facilities. In this study, physical (horizontal steel cables) and behavioral barriers (electric field) for fish protection were developed (Flexible FishProtector) and their effectiveness was investigated. The behavior of brown trout (Salmo trutta fario), rainbow trout (Oncorhynchus mykiss), grayling (Thymallus thymallus) and chub (Squalius cephalus) at the Flexible FishProtector was analyzed using video evaluation. The experimental setup was a non-scaled section model of a runoff river power plant. The used electric field induced a flight reaction at a corresponding distance to the Flexible FishProtector that significantly increased the protection rate. Furthermore, an increase in guiding efficiency was achieved with the use of a physical as well as a physical and behavioral barrier, supporting safe downstream migration with the narrower cable clearance (30 mm versus 60 mm). Full article
(This article belongs to the Special Issue Fish Passage at Hydropower Dams)
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25 pages, 71450 KiB  
Article
Protection and Guidance of Downstream Moving Fish with Electrified Horizontal Bar Rack Bypass Systems
by Julian Meister, Anita Moldenhauer-Roth, Claudia Beck, Oliver M. Selz, Armin Peter, Ismail Albayrak and Robert M. Boes
Water 2021, 13(19), 2786; https://doi.org/10.3390/w13192786 - 08 Oct 2021
Cited by 7 | Viewed by 2226
Abstract
Horizontal bar rack bypass systems (HBR-BS) are characterized by a horizontal bar rack (HBR) with narrow clear bar spacing of 10–20 mm and an adjacent bypass (BS) to efficiently protect and guide downstream moving fish at water intakes. The small bar spacing may [...] Read more.
Horizontal bar rack bypass systems (HBR-BS) are characterized by a horizontal bar rack (HBR) with narrow clear bar spacing of 10–20 mm and an adjacent bypass (BS) to efficiently protect and guide downstream moving fish at water intakes. The small bar spacing may lead to operational challenges, such as clogging and high head losses. This study investigated whether combining an HBR with a low-voltage electric field (e-HBR) allows one to increase the clear bar spacing while maintaining a high standard of fish protection and guidance efficiency. To this end, an HBR-BS with 20 mm bar spacing and an e-HBR-BS with 20 and 51 mm bar spacing were tested with spirlin (Alburnoides bipunctatus) and European eel (Anguilla anguilla) in a laboratory flume. The racks were electrified with 38 V pulsed direct current. The protection efficiency of the e-HBR with 51 mm was 96% for spirlin and 86% for eels, which are similar results to those of the HBR with 20 mm. Some eels passed through the e-HBR, but only when they were parallel to the rack. Fish injuries of variable severeness due to the electrification were observed. The results highlight the potential of hybrid barriers for the protection of downstream moving fish. However, fish injuries due to electricity may occur; and reporting applied voltage, electrode geometry, resulting electric field strength and the pulse pattern of the electrified rack setup is necessary to ensure comparability among studies and to avoid injuries. Full article
(This article belongs to the Special Issue Fish Passage at Hydropower Dams)
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16 pages, 5001 KiB  
Article
Relationship between Upstream Swimming Behaviors of Juvenile Grass Carp and Characteristic Hydraulic Conditions of a Vertical Slot Fishway
by Ping Cao, Xiangpeng Mu, Xiang Li, Baoligao Baiyin, Xiuying Wang and Wanyue Zhen
Water 2021, 13(9), 1299; https://doi.org/10.3390/w13091299 - 06 May 2021
Cited by 6 | Viewed by 2316
Abstract
The successful fish upstream movement through a dam/gate is closely associated with the hydraulic conditions of a fishway. To improve the passage efficiency, this study investigated the upstream swimming behaviors of juvenile grass carp, a representative fish of four major Chinese carps, under [...] Read more.
The successful fish upstream movement through a dam/gate is closely associated with the hydraulic conditions of a fishway. To improve the passage efficiency, this study investigated the upstream swimming behaviors of juvenile grass carp, a representative fish of four major Chinese carps, under characteristic hydraulic conditions of a designed vertical slot fishway model. The impacts of different discharges and baffle lead angles on the successful movement of test fish were analyzed, and the selection of the movement trajectory was studied through overlay of their upstream swimming trajectories on the water flow field resulting from numerical modeling. We found that under the same discharge, the percentage of successful test fish movement with a lead angle of 45° was higher than 60° and 30°. Within a fixed lead angle, the higher the discharge, the lower the percentage of successful movement. During upstream movement, the test fish had a preferred water velocity of 0.01–0.45 m/s in the pool, and avoided areas where the turbulence kinetic energy (TKE) was greater than 0.012 m2/s2. These results provide a basis for the hydraulic design of vertical slot fishways and a reference for studying swimming behaviors of other fish species. Full article
(This article belongs to the Special Issue Fish Passage at Hydropower Dams)
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10 pages, 1084 KiB  
Article
Validation of a Swimming Direction Model for the Downstream Migration of Atlantic Salmon Smolts
by Marcell Szabo-Meszaros, Ana T. Silva, Kim M. Bærum, Henrik Baktoft, Knut Alfredsen, Richard D. Hedger, Finn Økland, Karl Ø. Gjelland, Hans-Petter Fjeldstad, Olle Calles and Torbjørn Forseth
Water 2021, 13(9), 1230; https://doi.org/10.3390/w13091230 - 28 Apr 2021
Cited by 8 | Viewed by 2403
Abstract
Fish swimming performance is strongly influenced by flow hydrodynamics, but little is known about the relation between fine-scale fish movements and hydrodynamics based on in-situ investigations. In the presented study, we validated the etho-hydraulic fish swimming direction model presented in the River Mandal [...] Read more.
Fish swimming performance is strongly influenced by flow hydrodynamics, but little is known about the relation between fine-scale fish movements and hydrodynamics based on in-situ investigations. In the presented study, we validated the etho-hydraulic fish swimming direction model presented in the River Mandal from Southern Norway, using similar behavioral and hydraulic data on salmon smolts from the River Orkla in Central Norway. The re-parametrized model explained the variation of the swimming direction of fish in the Orkla system in same degree as the original model performed in the Mandal system (R2: 84% in both cases). The transferability of the model when using it from one river to predict swimming direction in the other river was lower (R2: 21% and 26%), but nevertheless relatively high given that the two localities differed in hydraulic conditions. The analyses thus provide support for the fact that the identified hydraulic parameters and their interaction affected smolt behavior in a similar way at the two sites, but that local parametrization of the base model is required. The developed etho-hydraulic models can provide important insights into fish behavior and fish migration trajectories and can be developed into prediction models important for the future development of behavioral downstream migration solutions. Full article
(This article belongs to the Special Issue Fish Passage at Hydropower Dams)
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20 pages, 7364 KiB  
Article
Turning Pools in Stepped Fishways: Biological Assessment via Fish Response and CFD Models
by Francisco Javier Bravo-Córdoba, Juan Francisco Fuentes-Pérez, Jorge Valbuena-Castro, Andrés Martínez de Azagra-Paredes and Francisco Javier Sanz-Ronda
Water 2021, 13(9), 1186; https://doi.org/10.3390/w13091186 - 25 Apr 2021
Cited by 12 | Viewed by 2927
Abstract
With the aim of building more compact fishways and adapting them to field conditions to improve their location by fish, it is common to use turning pools, reducing the longitudinal development of the construction. However, depending on their design, turning pools may affect [...] Read more.
With the aim of building more compact fishways and adapting them to field conditions to improve their location by fish, it is common to use turning pools, reducing the longitudinal development of the construction. However, depending on their design, turning pools may affect the hydraulic performance of the fishway and consequently the fish passage. To study these phenomena, turning pools in a vertical slot and in different configurations of submerged notches with bottom orifice fishway types were assessed. Both types of fishways were studied using numerical 3D models via OpenFOAM, a computational fluid dynamics software, in combination with fish responses, assessed with PIT (Passive Integrated Transponder) tag telemetry for three different species of potamodromous cyprinids in several fishways. Results show differences between the hydrodynamics of straight and turning pools, with lower values in the hydrodynamic variables in turning pools. Regarding fish behavior, the ascent was slower in turning pools but with no effect on passage success and without being a problem for fish migration. This information validates the use of turning pools as a key design component for fishways for studied species. Full article
(This article belongs to the Special Issue Fish Passage at Hydropower Dams)
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22 pages, 3108 KiB  
Article
Study of a Rock-Ramp Fish Pass with Staggered Emergent Square Obstacles
by Flavia Cavalcanti Miranda, Ludovic Cassan, Pascale Laurens and Tien Dung Tran
Water 2021, 13(9), 1175; https://doi.org/10.3390/w13091175 - 24 Apr 2021
Cited by 3 | Viewed by 2062
Abstract
A rock-ramp fish passage with square obstacles was experimentally and numerically studied in this work with the objective of investigating in detail the hydraulic behind such fishways and to evaluate the importance of the shape of the obstacles. The LES and VOF methods [...] Read more.
A rock-ramp fish passage with square obstacles was experimentally and numerically studied in this work with the objective of investigating in detail the hydraulic behind such fishways and to evaluate the importance of the shape of the obstacles. The LES and VOF methods were used for the simulations, and for the measurements, shadowgraphy and ADV were applied. Two different validations were successfully performed. In the first one, the experimental and numerical results of a chosen case were compared in detail. In the second validation, the focus was given to the stage-discharge. Following the validation, a numerical study was carried out to point out the differences in the flow characteristics from a configuration with square and circular obstacles. The discharge was nearly the same for both configurations, which implies different water depths. The results showed a lower velocity field, lower turbulent kinetic energy, and lower lateral fluctuations for the configuration with square blocks, which indicated a better passability for this geometry. However, it also presented a higher water depth, which led to a less attractive discharge. The differences in the flow generated in the two configurations indicated that the shape is an important modifiable parameter to be considered in the design process. Full article
(This article belongs to the Special Issue Fish Passage at Hydropower Dams)
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21 pages, 5550 KiB  
Article
Numerical Study of Three-Dimensional Surface Jets Emerging from a Fishway Entrance Slot
by Lena Mahl, Patrick Heneka, Martin Henning and Roman B. Weichert
Water 2021, 13(8), 1079; https://doi.org/10.3390/w13081079 - 14 Apr 2021
Cited by 3 | Viewed by 2139
Abstract
The efficiency of a fishway is determined by the ability of immigrating fish to follow its attraction flow (i.e., its jet) to locate and enter the fishway entrance. The hydraulic characteristics of fishway entrance jets can be simplified using findings from widely investigated [...] Read more.
The efficiency of a fishway is determined by the ability of immigrating fish to follow its attraction flow (i.e., its jet) to locate and enter the fishway entrance. The hydraulic characteristics of fishway entrance jets can be simplified using findings from widely investigated surface jets produced by shaped nozzles. However, the effect of the different boundary conditions of fishway entrance jets (characterized by vertical entrance slots) compared to nozzle jets must be considered. We investigate the downstream propagation of attraction jets from the vertical slot of a fishway entrance into a quiescent tailrace, considering the following boundary conditions not considered for nozzle jets: (1) slot geometry, (2) turbulence characteristics of the approach flow to the slot, and (3) presence of a lateral wall downstream of the slot. We quantify the effect of these boundary conditions using three-dimensional hydrodynamic-numeric flow simulations with DES and RANS turbulence models and a volume-of-fluid method (VoF) to simulate the free water surface. In addition, we compare jet propagation with existing analytical methods for describing jet propagations from nozzles. We show that a turbulent and inhomogeneous approach flow towards a vertical slot reduces the propagation length of the slot jet in the tailrace due to increased lateral spreading compared to that of a jet produced by a shaped nozzle. An additional lateral wall in the tailrace reduces lateral spreading and significantly increases the propagation length. For highly turbulent flows at fishway entrances, the RANS model tends to overestimate the jet propagation compared to the transient DES model. Full article
(This article belongs to the Special Issue Fish Passage at Hydropower Dams)
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15 pages, 2517 KiB  
Article
Fishways as Downstream Routes in Small Hydropower Plants: Experiences with a Potamodromous Cyprinid
by Francisco Javier Sanz-Ronda, Juan Francisco Fuentes-Pérez, Ana García-Vega and Francisco Javier Bravo-Córdoba
Water 2021, 13(8), 1041; https://doi.org/10.3390/w13081041 - 10 Apr 2021
Cited by 13 | Viewed by 2965
Abstract
Fish need to move upstream and downstream through rivers to complete their life cycles. Despite the fact that fishways are the most commonly applied solution to recover longitudinal connectivity, they are not considered viable for downstream migration. Therefore, alternative facilities are recommended to [...] Read more.
Fish need to move upstream and downstream through rivers to complete their life cycles. Despite the fact that fishways are the most commonly applied solution to recover longitudinal connectivity, they are not considered viable for downstream migration. Therefore, alternative facilities are recommended to facilitate downstream migration. However, a few recent studies have disagreed with this general assumption, showing the potential for bidirectional movements. This study advances our understanding of the potential of fishways for downstream migration by studying their efficiency in a run-of-the-river hydropower plant in the Duero River (Spain). To achieve this, downstream movements of the Iberian barbel (n = 299) were monitored in a stepped fishway for two years with passive integrated transponder (PIT)-tag technology, considering the effect of fish origin and release zone. The results showed that 24.9% of barbels descended through the fishway, with the origin and release zone affecting the fishway location. In addition, downstream movements were observed throughout the whole year, except in winter. The study concludes that, under specific scenarios, fishways could act as safe alternative routes for downstream migration. Full article
(This article belongs to the Special Issue Fish Passage at Hydropower Dams)
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21 pages, 4534 KiB  
Article
A Parametric Approach for Determining Fishway Attraction Flow at Hydropower Dams
by Patrick Heneka, Markus Zinkhahn, Cornelia Schütz and Roman B. Weichert
Water 2021, 13(5), 743; https://doi.org/10.3390/w13050743 - 09 Mar 2021
Cited by 5 | Viewed by 3300
Abstract
High discharges at hydropower plants (HPP) may mask fishway attraction flows and, thereby, prevent fishes from locating and using fishways critical for their access to upstream spawning and rearing habitats. Existing methods for determining attraction flows are either based on simple guidelines (e.g., [...] Read more.
High discharges at hydropower plants (HPP) may mask fishway attraction flows and, thereby, prevent fishes from locating and using fishways critical for their access to upstream spawning and rearing habitats. Existing methods for determining attraction flows are either based on simple guidelines (e.g., a proportion of HPP discharge) that cannot address the spatial and temporal complexity of tailrace flow patterns or complicated studies (e.g., combinations of detailed hydraulic and biological investigations) that are expensive and time-consuming. To bridge this gap, we present a new, intermediate approach to reliably determine attraction flows for technical fishways at small to medium-sized waterways (mean annual flow up to 400 m3/s). Fundamental to our approach is a design criterion that the attraction flow should maintain its integrity as it propagates downstream from the fishway entrance to beyond the highly turbulent zone characteristic of HPP tailraces to create a discernable migration corridor connecting the fishway entrance to the downstream river. To implement this criterion, we describe a set of equations to calculate the width of the entrance and the corresponding attraction discharge. Input data are usually easy to obtain and include geometrical and hydraulic parameters describing the target HPP and its tailrace. To confirm our approach, we compare model results to four sites at German waterways where the design of attraction flow was obtained by detailed experimental and numerical methods. The comparison shows good agreement supporting our approach as a useful, intermediate alternative for determining attraction flows that bridges the gap between simple guidelines and detailed hydraulic and biological investigations. Full article
(This article belongs to the Special Issue Fish Passage at Hydropower Dams)
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25 pages, 7560 KiB  
Article
Swimming Behavior of Downstream Moving Fish at Innovative Curved-Bar Rack Bypass Systems for Fish Protection at Water Intakes
by Claudia Beck, Ismail Albayrak, Julian Meister, Armin Peter, Oliver M. Selz, Claudia Leuch, David F. Vetsch and Robert M. Boes
Water 2020, 12(11), 3244; https://doi.org/10.3390/w12113244 - 19 Nov 2020
Cited by 18 | Viewed by 3092
Abstract
New types of fish guidance structures with vertical curved bars and a subsequent bypass system represent a promising technical solution for the protection and guidance of downstream moving fish at run-of-river hydropower plants and water intakes. These so-called “curved-bar rack bypass systems” (CBR-BSs) [...] Read more.
New types of fish guidance structures with vertical curved bars and a subsequent bypass system represent a promising technical solution for the protection and guidance of downstream moving fish at run-of-river hydropower plants and water intakes. These so-called “curved-bar rack bypass systems” (CBR-BSs) function as a mechanical behavioral barrier and are characterized by low hydraulic losses, a symmetrical downstream flow field and an overall high fish guidance efficiency in the laboratory for a wide array of European freshwater fish species. This paper presents the results of the hydraulic and live-fish laboratory tests of an optimized CBR-BS configuration with a bar spacing of 50 mm and 30° rack angle to the flow direction. The tests were conducted with six different fish species in an ethohydraulic laboratory flume at different approach flows (0.5 m/s, 0.7 m/s) and different bypass entrance velocities (0.6–1.0 m/s). A numerical model was used to simulate the flow fields in the CBR-BS in order to link the fish behavior to the hydrodynamic cues created by the CBR-BS. Lower approach flow velocities decreased the hydraulic cues of the CBR, which led to more rack passages. A 20% velocity increase towards the bypass entrance significantly increased the fish guidance efficiency compared to a 40% velocity increase. The tested CBR-BS resulted in overall higher interspecies fish protection and guidance efficiencies compared to the more commonly applied horizontal-bar rack with a narrow bar spacing of 20 mm. Recommendations for a sustainable and cost-effective application of CBR-BSs are given. Full article
(This article belongs to the Special Issue Fish Passage at Hydropower Dams)
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Review

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13 pages, 2590 KiB  
Review
Migrations of Young Fish in Anthropogenically Transformed Rivers: Responses of Cyprinids and Percids to Ecological Filters and Barriers
by Dmitrii S. Pavlov, Vasilii V. Kostin and Victor N. Mikheev
Water 2021, 13(9), 1291; https://doi.org/10.3390/w13091291 - 04 May 2021
Cited by 2 | Viewed by 1985
Abstract
Downstream migration (DSM) of larvae and fry is an important phase of the life cycle of fish as it allows them to disperse, and it increases the size and diversity of the populations via them extending rearing grounds, exchanging genes, and avoiding competition [...] Read more.
Downstream migration (DSM) of larvae and fry is an important phase of the life cycle of fish as it allows them to disperse, and it increases the size and diversity of the populations via them extending rearing grounds, exchanging genes, and avoiding competition and cannibalism. Two numerous and diverse fish families of the Eurasian rivers, Cyprinidae and Percidae, are well adapted to the conditions of the riverine continuum. Having said that, the regulation of rivers (construction of dams and water reservoirs) drastically changes their hydrology and topography. In this work, we argued that novel conditions of transformed river habitats influence the DSM of young cyprinids and percids in different ways. The published results on fish DSM and spatial distribution in nine European reservoirs (Russia, Kazakhstan, Czech Republic, Bulgaria) in comparison with untransformed rivers were reanalyzed from the viewpoint of this argument. Changes in the major characteristics of DSM of young cyprinids and percids, i.e., intensity, diel (24-h period), and seasonal patterns of migrations, as caused by anthropogenic transformation of the rivers, were revealed. We found that the novel ecological barriers and filters associated with different parts of water reservoirs differently influence the lateral and longitudinal movements, and the diel and seasonal dynamics of DSM of cyprinids and percids. These effects result in significantly more intensive emigration of young percids compared to cyprinids from reservoirs with deep-water intakes. At the scale of the whole regulated river, the morphological complexity (topography) of the reservoir plays a pivotal role in controlling the intensity of the DSM of young fish. Measures for the conservation and restoration of percid and cyprinid populations should be different. Full article
(This article belongs to the Special Issue Fish Passage at Hydropower Dams)
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