Struthan Bhraigh nan Allt, Scotland: Design study for the restoration of a Relic Course and Peatland Hydrology
Date: February 2018
For: Lochaber Fisheries Trust
Type: Options appraisal and design guidance
The Struthan Bhraigh nan Allt is located on the Ardnamurchan Peninsula and is part of the Ardnamurchan Burns SAC. It is designated for its freshwater pearl mussel population, and is currently in unfavourable condition. Previous reports by RRC and Envirocentre had assessed the site and provided some options for improvement. Lochaber Fisheries Trust wished to refine a relic course restoration option into a practical and achievable design to inform contractors to be able to undertake the peatland and channel restoration work.
There are three drivers behind the project; peatland condition, freshwater pearl mussel populations and natural river morphology. RRC provided detailed advice on re-connecting the relic channel to result in the improvement of each driver.
Using information from a desktop and site assessment as well as an external topographic survey, the optimal course for the restoration was plotted. This was supplemented with detail on the ideal gradient and cross-sectional shape and dimensions of the new channel.
RRC also produced a method statement which included guidance on in-filling the current channel and blocking small ditches in tandem with the main restoration works. Lochaber Fisheries Trust are now able to use this report to inform and guide local contractors when the work goes ahead.