Gayle Beck Restoration – Morphological Hydraulic Modelling

Location: Gayle Beck                                                                                       Client: Ribble Rivers Trust

Challenge

The Ribble Rivers Trust (RRT) identified that the Gayle Beck in the Yorkshire Dales had insufficient fish habitats and was unable to support the sustainable migration of fish. As such, the Gayle Beck was failing the Water Framework Directive for having poor Ecology. The RRT commissioned JBA Consulting to investigate potential river restoration options to improve fish habitat and passage.

Solution

We undertook hydraulic modelling to assess the impact of adding woody debris features into Gayle Beck. Woody debris has been successfully used on a number of river restoration schemes across the UK, as they have been proven to increase habitat diversity in rivers. The installation of woody debris within a river provides a wide range of enhancements, from slowing down the flow of water, encouraging gravel deposition, trapping organic matter and providing shade. These offer excellent benefits for fish by providing migration routes, additional habitats and spawning locations, and a wider range of food sources. Different combinations of woody debris were represented in the hydraulic model to assess the impact that this would have on the flow regime and sediment movement patterns across a 300m reach of the Gayle Beck.

Benefit

The addition of woody debris in the channel creates a greater diversity in flow velocities, generating areas of high and low velocity. This will lead to areas of sediment erosion where the channel is constricted, and sediment deposition directly downstream where the channel widens and flow velocities reduce.

The model results indicate that fish will benefit from the following:

  • A greater range of flows facilitates improved fish migration
  • bed scour generates pool features in the channel, creating a valuable fish habitat
  • Sediment deposition generates bar features and riffles, a valuable fish habitat

Want to know more?

Email Matt Hemsworth for more on our Gayle Beck Restoration Project. You can also learn more about our catchment and river restoration services by visiting our dedicated webpage here.



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