Revetting and supporting river banks

Bank-side erosion is a common riverine problem, particularly in fast flowing (artificially straightened) channels and there are a number of revetment techniques which can be employed, the choice of erosion prevention measure employed in heavily dependent on site conditions and as such there is no one cure all. ‘Hard’ engineering solutions used in the past and to some extent still today can be effective but carry their own set of disadvantages. The A.G.A Group has instead focused on bio-engineering techniques to reduce erosion. By using such materials as coir, willow and other natural solutions can be found to support and revet banks.

Coir is a very effective natural material which can either be laid down under the top-soil in mats which help to reinforce the bank or used as edging to act as a barrier to erosion. After the turf reinforcement mats are laid down and pegged in plant species soon colonise. The mats can even be seeded after laying and the coir acts as the perfect germination medium, depending on the time of year banks can look naturalised again in as little as 6-8 weeks.

Where bank-sides are heavily eroded there may be the opportunity to create new more robust bank-sides and back fill behind. This bio-engineering methodology is often employed by the A.G.A Group and proves to be extremely effective. By using pre-planted coir fibre rolls placed on faggots to create ‘new’ bank-sides erosion can be effectively stopped.

Utilising silt from the river bed to backfill behind the new structure this methodology not only acts as a robust erosion prevention techniques but also removes a quantity of silt from the river bed without the need for consents. It can therefore be seen as a multi-functional technique to rehabilitate river banks which are suffering from erosion without the use of ‘hard’ revetments which are both unsightly and environmentally questionable.