Once again we relied on volunteers to assist with riverbank restoration on the Girvan. Without volunteers, the Trust is really pushed to deliver this type of work with our limited staff. Anyway, today we were assisted by two students and a staff member from SRUC, Riverside Campus. Sally Gray brought along Elidh and Danny, both Countryside managers to help with the work and I think they all enjoyed themselves. We couldn’t have achieve so much without their assistance so a big thanks from the Trust to them.
In the last week, ART staff put together about 40+ faggots made of brash from a felled woodland. If we hadn’t used it, it would have been burnt or left to decompose on site so either way, it has now been put to good use to stabilise severe erosion on the Girvan and will lock up carbon for some years ahead. Bank stabilisation using ‘green’ technologies are a much more environmentally friendly way to address erosion problems on rivers and are more likely to be supported by SEPA in preference to the old solutions involving rock armour, gabon baskets and levies that are no longer in favour unless of course there’s real justification. This severe erosion that has long impacted the middle reaches of the Girvan and downstream occurs as a direct result of morphological changes that were made to the river over 200 years ago when manual labour was used to straighten and reroute the river, presumably to improve agriculture on the flood plain. We can still see signs of the meanders on the floodplain in some satellite and drone imagery and levies occur along much on the mainstem. The river is really only trying to remainder as it once did naturally and so while leaving it to do so may be an option, the problems lie with the loss of agricultural land and the silt and soil that would be lost downstream ruining spawning gravels and adding nutrients, (particularly phosphates) that can reduce water quality for many years. This really isn’t an option so we are looking to find acceptable solutions.
In 2011, Brain Shaw and I visited these 2 sites to see if we could suggest solutions that the estate could achieve without too great an expense (I’ll try to find some photos taken then). SEPA were also in attendance and it was agreed, the worst erosion point could have tree butts and root wads added into the bank to help stabile the bank. This was performed by a local contractor the following year under a CAR licence and while it may have helped to some extent, it didn’t solve the problem entirely as there was only a small section tackled due to the cost. Another contributing factor is livestock that have free access to the banks and sheep in particular have been detrimental to bank stability. As part of this project, both erosion points will be fenced to exclude livestock.
Since 2012 the banks have continued to crumble and some of the trees trunks washed out and are now stuck midstream. We needed a better solution and ART suggested we try willow spilling and planting on the eroding sections (all performed under the CAR licence. Last April along with another group of volunteers, we set about trialling willow spilling and willow faggots to compare results. Both have worked well and erosion has ceased at both and a considerable volume of silt and fine sediment has built up behind the willow bundles at the upper stretch.
Todays work of installing brash fagots was a continuation of last years willow faggots. The section we worked on today eroded baldly last winter so we decided to extend our efforts only this time using brash bundles. We built them at least 2 faggots high today and in the worst areas, two layers deep. They were staked in with a combination of willow and hardwood stakes cut from waste.
The willow we hope will root and ensure there’s plenty of buffering branches to reduce the force of the water on the bank. The branches that develop will provide shade and cover for fish, and the roots that trail on the water will provide refuge from predators when they enter a pool. Sally and Elidh cut a bucket load of willow cuttings while Danny, Struan, Muir and myself placed and staked the faggots into the toe of the bank. Once we had finished, staking, the cuttings were planted across the entire area. We also planted some tall cuttings about 4 -6′ long that we know should root fine and give height quickly.
The entire work took us until early afternoon when we then decided to add more willow where we had left off last year with the spilling at the erosion downstream. This spilling had been heavily grazed by sheep earlier this year but now that they are off this land, they are again doing well. Roots can be seen trailing in the water from the spilling and there not a bit of erosion taken place here since we installed it last April. Muir and Struan added some 7 -8′ willow poles we cut earlier in April and they are now doing very well. This was a bit experimental (as this entire site is really) and we are sure they will offer an good alternative in deep water situations. We could do with a few more brash bundles to stake into the bank behind these willows but we will get to that eventually. Today we added a few more thin willow cutting extending this section by another 12′ and we will watch to see how these do.
I’m quite certain that in 4 – 5 years time, these two banks will be stable and covered in foliage. The pools should have better fish cover and greater fish populations and sediment heading downstream from here will be a thing of the past.
We may make the odd mistake and have an occasional failure, but on the whole, we are making leaps and bound in developing and understanding what works best and is most cost effective. ART take these jobs on to demonstrate to anglers, owners and clubs how they may improve their own beats. Anyone wanting to do something similar or advice on how to approach this can give us a call in the office where we would be very please to discuss this with you and help where we can.
lot of the problems at kilkerran are due to gravel extraction from the 70s and early 80s . Having fished kilkerran from 1962 there was not much sign of bank erosion until after the extraction. The box pool came off worst when the bank gave way taking all the sand martins nests with it along with trees and the large concrete drain pipe. Erosion then continued towards Drumburle bridge.
Thanks for this Colin. Where exactly did the gravel extraction take place? Presumably the pipe carried water from the gravel pit?