Riverbank Conservation Ltd

Erosion Control & Bank Stabilisation

Introduction

Since the Middle Ages willow has been used to stabilise the banks of rivers, streams, canals and other watercourses. Although alternatives have been used, the last 20 years have seen resurgence in the use of this natural technique. With modern implementations, Willow Spiling is now the natural choice to protect banks and prevent erosion.

Rivers and streams are affected by excessive amounts of rainfall and this is the primary cause of erosion although many other factors can affect watercourses. Increased awareness of environmental issues from both the government and the general public has given rise to a re-evaluation of erosion control techniques and the need to consider the wider needs of both human and wildlife. There has been a greater emphasis placed on regeneration. Our waterways have suffered neglect after their use for navigation, industrialisation and flood protection and have also been affected by changes in land drainage due to farming. During the heavy industrial years little regard or consideration has been given to the affects our modern life may have on rivers. This may well be the cause of the problems you are experiencing now but meandering rivers are also likely to adjust their path through the landscape and erosion can be a gradual transition or a more rapid experience.

Personal Care

It is important to consider a bank stabilisation solution carefully as although a ‘cure’ can be provided to restore a bank, it is also necessary to think about the implications of carrying out the work and the effects on the surrounding environment. Rivers and watercourses have very complex systems and can be sensitive to changes made even several miles further up or down stream. A riparian landowner, those who own property adjacent to rivers and waters, are responsible for the protection of their banks. However, anyone carrying out work to a river is also responsible for any damage they may cause to a third party. Each set of circumstances will be unique and it is seldom possible to predict accurately the affect change will have elsewhere within the watercourse. Erosion can provide benefits to a river and this does need to be taken into account when we offer our clients the best advice and service available. We strongly recommend that you seek professional advice and discuss your concerns and plans with the relevant bodies before contracting work to your watercourse. We can help by putting you in touch with the relevant authorities and agencies and ensure all parties are comfortable with the solutions we would recommend.

Bank Stabilisation Considerations

The main consideration when applying bank stabilisation techniques must of course be the natural course of the waterway and how its adverse affect can be arrested but there are also many other factors that must be gauged. The slope of the bank and its material composition will affect the speed and form the erosion will take. The likelihood of flooding, the density and type of bank side vegetation, whether previous methods of erosion control have been employed and whether there is evidence of any up or downstream changes that may have affected the water flow, for example a bridge or weir, all contribute. The bank stabilisation solution must consider and cater for all these factors.

Wildlife habitat, proximity to buildings or other man made structures and the specific needs and requirements of the customer all form part of the overall solution.

The alternatives to Willow Spiling, such as steel and concrete usually have a longer installation period and are subsequently more expensive to install. Riverbanks’ soft engineering solution is very cost effective and has a greater aesthetic appeal with a living woven barrier forming an immediate protection and providing habitat recreation.
Blue Water

Blue Rushes 2

Blue Ripple 2

Techniques of bank stabilisation

Spiling

Spiling, usually involves, driving live willow stakes vertically into the eroded bank and then weaving living willow shoots (withies) horizontally between and around the stakes. The space behind the willow wall to the existing bank is then filled with soil to provide an area for the willow roots to grow. This work is normally carried out between November and April during the harvesting of the willow (dependent upon the season) and should be installed within three weeks of harvest. As willow does not grow easily in shade it is sometimes necessary to carry out coppice work on nearby trees. A natural and regenerating wall will very quickly develop from a Willow Spiling installation. The results are superbly functional and aesthetically pleasing.

Spiling will require maintenance and we are very keen to carry out the first years work to check bank stability, the adherence and growth rate of the willow and of the affect on the natural wildlife. We are happy to include this in the costs and contract for the installation of the works. This maintenance is essential to maintain an effective system. We can offer an additional service, providing training for future years maintenance or discuss an ongoing maintenance programme with you and your team.

Although Riverbank Conservation specialise in soft engineering solutions to erosion control and bank stabilisation we are also conversant with hard engineering solutions and these are sometimes unavoidable due to practical or economic reasons, a combination of both can often provide a good overall solution.

Spiling rooted & growing after two months

Faggoting

Faggots or fascines are bundles of willow or sometimes hazel, bound together and used for various stabilisation and revetment purposes. Faggoting is an ancient technique, undergoing something of a revival as the advantages of 'soft' revetments are realised. The faggots slow the flow of moving water and trap silt and sediment, and the buried branches then help consolidate the sediments against renewed erosion. The faggots are arranged to produce a ‘mattress’ and held in place using stakes. Their use is common in estuaries, where it is common to have a large siltation deposit, to prevent erosion.

Live faggots (but dormant) can be provided to deliver immediate growth and rapid bank vegetation. As the faggots will root, it is important to consider the width of the channel in which they are installed. The natural growth of the material may narrow channels and could cause flooding. More often faggots are installed without the possibility of taking root (dead form) to prevent erosion and help with the siltation process.