A 500-metre stretch of the Quharity Burn has been restored to return the river to its historical course using nature-based solutions implemented on the Kinnordy Estate near Angus.
Funded by NatureScot’s Nature Restoration Fund, the design phase of the project began in September 2022, with ‘nature-based’ designs being developed by RSK Group company CBEC eco-engineering. This followed on from an original catchment-scale scoping study delivered by CBEC in March 2021, which prioritised this site as one of four where restoration would offer significant improvements to the natural functioning of the river and floodplain.
The design phase involved the application of a ‘stage zero’ approach that saw the burn redirected through the adjacent floodplain. Consideration was also given to measures that would improve localised flow attenuation and flood water storage. In addition to biodiversity benefits, such measures have potential reductions to downstream flood risk, which is important in terms of helping to sustainably mitigate against the future effects of climate change. In July 2023, construction works were procured, a process led by Advantage RSK. Construction began in September 2023, led by contractors CR Contracting North Ltd.
In order to deliver the designs and support construction, CBEC carried out a number of field surveys and computer-based technical assessments, as well as supporting the estate with stakeholder engagement, project management and construction supervision.
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CBEC Project Manager Alison Wilson said: “We encouraged the burn into the floodplain by excavating a simple channel design to guide the flow towards the natural low points. The design is sustainable and, once the vegetation has fully re-established, will require no ongoing maintenance or management. It is a unique opportunity to employ a nature-based approach to fully reinstate a ‘wandering’ channel network through a floodplain that has been disconnected from its river for some time.
“We installed 18 large wood structures in strategic locations to help further guide the flow and to improve habitat for aquatic invertebrates, fish and terrestrial species within the new channel areas. Two sections of sustainable large wood bank protection were also constructed to minimise the risk of the channel diverting back into its original course.”
The restoration site is upstream from the Loch of Lintrathen, a designated water supply for the Angus area. Alison said that this required close liaison with Scottish Water to ensure that the construction process did not result in short-term impacts to the loch through excess silt release.
CBEC Design Director Dr Hamish Moir said: “This is perhaps the first project of its kind upstream from a drinking water reservoir that has the potential to naturally improve the water quality going into the loch through river restoration activities.
“The site experienced the full force of Storm Babet less than one month after construction had finished, in a period before it had had a chance to recover. However, as a nature-based design, the scheme was remarkably resilient.”
Antony Gifford, the owner of Kinnordy Estate, said: “One only needs to look at the photos to see the difference this has made to this section of the river and floodplain in terms of renaturalising the site. That it can support flood resilience downstream and bring benefits to the wider catchment is truly amazing. I hope that we can replicate the success at other sites on the burn in the future.”
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