Nether Cambushinnie Bank Protection – 2022 Update

The upper reaches of the Allan Water between Kinbuck and Greenloaning mostly consists of active farmland. This reach also consists of sandy soils which mean that due to a lack of riparian tree cover and land use within the river corridor, the banks of the river are prone to erosion. This erosion leads to excess sedimentation in the river – the buildup of fine sediments and sands in a river system – which has a negative effect on in-stream habitat. This impacts the diversity of macroinvertebrates, and limits habitat for species such as Atlantic salmon and freshwater pearl mussel. It also results in the loss of land for landowners.

In 2017, working with the local landowner at Nether Cambushinnie farm, we applied to the Agri-Environment Climate Scheme (AECS) to restore 95 metres of river bank using green bank protection techniques.

The works involved reprofiling 95 metres of river bank, along with the installation of willow spiling and willow faggots which were pinned to the bank face to encourage willow growth. A grass seed mix was then sown on the bank to help bind the soils topped off with a hessian geotextile to protect the bank face until vegetation could establish. The section was also fenced off to prevent livestock access.

Green bank protection is a great tool to reduce erosion in a green and environmentally friendly way. It reduces the reliance on hard bank protection measures such as gabion baskets or concrete which are carbon intense options, while also providing a boost to habitats locally with overhanging vegetation and increased riparian tree cover.

We recently returned to the site in November 2022 to see how the protection has been faring after 5 years, and the site is holding up well. The willow that’s been planted has grown to 3-5m in length. The mixture of native willow and the osier variety, used for it’s structural rigidity and flexibility, has worked well and both have integrated on the river banks.

The river level was fairly high on the day we visited so the toe of the bank was obscured, however the general profile of the bank has been maintained and the willow spiling and geotextile has provided enough of a barrier to erosion to allow for the willow to establish and bind the bank together.

The restricting of livestock to the small peninsula has resulted in the regeneration of other bank binding vegetation such as gorse along with the unhindered natural regen of native broadleaf species, along with unhindered growth of the planted willow.

The trees in tree tubes that were planted on site haven’t been as successful as we’d have liked, with deer browsing and competition from unhindered grass species playing a factor. The use of some form of natural weed mat, such as straw or sheeps wool along with marginally higher tree tubes in future may allow for better growth.

The site serves as a good demonstration for the benefits of green bank protection, particularly involving willow, due to its versitility and relative low cost.