Modelling mitigation measures for smolt migration at dammed river sections

Marcell Azabo-Meszaros*, Torbjørn Forseth, Henrik Baktoft, Hans-Petter Fjeldstad, Ana T. Silva, Karl Øystein Gjelland, Finn Økland, Ingebrigt Uglem, knut Alfredsen

*Corresponding author for this work

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Abstract

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, which 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.
Original languageEnglish
Article numbere2131
JournalEcohydrology (Online)
Volume12
Issue number7
ISSN1936-0584
DOIs
Publication statusPublished - 2019

Keywords

  • Downstream migration
  • Mitigation assessment
  • Hydraulic modelling
  • Ecohydraulics
  • Atlantic salmon

Cite this

Azabo-Meszaros, M., Forseth, T., Baktoft, H., Fjeldstad, H-P., Silva, A. T., Gjelland, K. Ø., ... Alfredsen, K. (2019). Modelling mitigation measures for smolt migration at dammed river sections. Ecohydrology (Online), 12(7), [e2131]. https://doi.org/10.1002/eco.2131
Azabo-Meszaros, Marcell ; Forseth, Torbjørn ; Baktoft, Henrik ; Fjeldstad, Hans-Petter ; Silva, Ana T. ; Gjelland, Karl Øystein ; Økland, Finn ; Uglem, Ingebrigt ; Alfredsen, knut. / Modelling mitigation measures for smolt migration at dammed river sections. In: Ecohydrology (Online). 2019 ; Vol. 12, No. 7.
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keywords = "Downstream migration, Mitigation assessment, Hydraulic modelling, Ecohydraulics, Atlantic salmon",
author = "Marcell Azabo-Meszaros and Torbj{\o}rn Forseth and Henrik Baktoft and Hans-Petter Fjeldstad and Silva, {Ana T.} and Gjelland, {Karl {\O}ystein} and Finn {\O}kland and Ingebrigt Uglem and knut Alfredsen",
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Azabo-Meszaros, M, Forseth, T, Baktoft, H, Fjeldstad, H-P, Silva, AT, Gjelland, KØ, Økland, F, Uglem, I & Alfredsen, K 2019, 'Modelling mitigation measures for smolt migration at dammed river sections', Ecohydrology (Online), vol. 12, no. 7, e2131. https://doi.org/10.1002/eco.2131

Modelling mitigation measures for smolt migration at dammed river sections. / Azabo-Meszaros, Marcell; Forseth, Torbjørn; Baktoft, Henrik; Fjeldstad, Hans-Petter; Silva, Ana T.; Gjelland, Karl Øystein; Økland, Finn; Uglem, Ingebrigt; Alfredsen, knut.

In: Ecohydrology (Online), Vol. 12, No. 7, e2131, 2019.

Research output: Contribution to journalJournal articleResearchpeer-review

TY - JOUR

T1 - Modelling mitigation measures for smolt migration at dammed river sections

AU - Azabo-Meszaros, Marcell

AU - Forseth, Torbjørn

AU - Baktoft, Henrik

AU - Fjeldstad, Hans-Petter

AU - Silva, Ana T.

AU - Gjelland, Karl Øystein

AU - Økland, Finn

AU - Uglem, Ingebrigt

AU - Alfredsen, knut

PY - 2019

Y1 - 2019

N2 - 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, which 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.

AB - 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, which 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.

KW - Downstream migration

KW - Mitigation assessment

KW - Hydraulic modelling

KW - Ecohydraulics

KW - Atlantic salmon

U2 - 10.1002/eco.2131

DO - 10.1002/eco.2131

M3 - Journal article

VL - 12

JO - Ecohydrology (Online)

JF - Ecohydrology (Online)

SN - 1936-0584

IS - 7

M1 - e2131

ER -

Azabo-Meszaros M, Forseth T, Baktoft H, Fjeldstad H-P, Silva AT, Gjelland KØ et al. Modelling mitigation measures for smolt migration at dammed river sections. Ecohydrology (Online). 2019;12(7). e2131. https://doi.org/10.1002/eco.2131