Metrics to assess how longitudinal channel network connectivity and in-stream Atlantic salmon habitats are impacted by hydropower regulation

Willem B. Buddendorf, Iain A. Malcolm, Josie Geris, Mark E. Wilkinson, Chris Soulsby

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19 Citations (Scopus)
15 Downloads (Pure)


Habitat fragmentation in channel networks and riverine ecosystems is increasing globally due to the construction of barriers and river regulation. The resulting divergence from the natural state poses a threat to ecosystem integrity. Consequently, a trade-off is required between the conservation of biodiversity in channel networks and socio-economic factors including power generation, potable water supplies, fisheries and tourism. Many of Scotland's rivers are regulated for hydropower generation but also support populations of Atlantic salmon (Salmo salar L.) that have high economic and conservation value. This paper investigates the use of connectivity metrics and weightings to assess the impact of river barriers (impoundments) associated with hydropower regulation on natural longitudinal channel connectivity for Atlantic salmon. We applied two different weighting approaches in the connectivity models that accounted for spatial variability in habitat quality for spawning and fry production and contrasted these models with a more traditional approach using wetted area. Assessments of habitat loss using the habitat quality weighted models contrasted with those using the less biologically relevant wetted area. This highlights the importance of including relevant ecological and hydrogeomorphic information in assessing regulation impacts on natural channel connectivity. Specifically, we highlight scenarios where losing a smaller area of productive habitat can have a larger impact on Atlantic salmon than losing a greater area of less suitable habitat. It is recommended that future channel connectivity assessments should attempt to include biologically relevant weightings, rather than relying on simpler metrics like wetted area which can produce misleading assessments of barrier impacts.
Original languageEnglish
Pages (from-to)2132-2142
Number of pages11
JournalHydrological Processes
Issue number12
Early online date2 May 2017
Publication statusPublished - 15 Jun 2017

Bibliographical note

Thanks to the Scottish Government's Hydro Nation Scholars Program for funding WBB to do this research. Also, many thanks to colleagues at Marine Science Scotland and the James Hutton Institute for providing some of the datasets used in this work. The authors thank the anonymous referees for constructive feedback on the manuscript.


  • hydropower
  • river regulation
  • Atlantic salmon
  • longitudinal channel connectivity
  • river network
  • weighting


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