Bristol Avon River Bank Stabilisation & in Stream Habitat Works
Ecolibrium were given permission to carry out bank stabilisation works on a private property
on the Bristol Avon.
The property is located on the outside bend of the River and had
experienced an accelerated rate of erosion over the last couple of years. The site had a
number of challenges due to the depth of water, the steep gradient of the river bank and
the limited access required for any machinery.
What did we do?
- Cleared all vegetation prior to works including, pollarding a mature Sallow and Hawthorn, removed small rowan trees, brushcut, strimmed and sprayed bank side vegetation, hand pulled invasive Himalayan Balsam and rotovated the upper banks.
- Created a 100m long live willow revetment at the toe of the eroding bank.
- Created a deep rooted marginal zone at the bottom of the river bank by planting a community of native riverside plant species.
- Seeded upper banks with a local wild meadow and grass seed mix.
- Introduced two live willow tree deflectors at up end and downstream end of revetment to dissipate rivers energy and take flow away from the river bank.
How did we do it?
- Prior to works starting Ecolibrium visited the site and carried out a detailed topographical survey of the River bank and surrounding land. The survey allowed us to evaluate the scale of works, and helped to identify safe methods of working in and around water.
- Close liaison followed with the client and the Environment Agency, to produce comprehensive drawings, method statements and risk assessments to form a proposed plan of the project.
- Permission was granted from the adjacent landowner to source local Willow material to be utilised as part of the lower bank stabilisation works.
- Course Woody Debris (CWD), and Large Woody Debris (LWD), was secured into thefoot of the bank to provide protection from erosion and to form in channel habitat and refuge for various fish species.
- Once the bank side vegetation had been stripped, a woven natural bio-degradable material was fixed in place to prevent soil erosion from heavy rain and river levels rising.
- 300 marginal plug plants were planted along the bottom of the river bank to provide a marginal zone. This provided a much needed root system to protect the bank as well as providing a habitat for many invertebrates and wild fowl.
- A local wild flower and grass seed mix was sown to stabilise the upper banks and bank stabilising shrubs were planted in order to produce a good amount of root stock to hold the bank together.
What were the outcomes?
- The project was delivered to an extremely high standard, within the time limit and on budget.
- Over 300 plants and 5kg of local wildflower and grass seed mix were planted and spread to form a diverse plant community that has benefited many invertebrates including bees, damsel and dragonfly’s.
- 100m of live willow has helped to stabilise the bank and provide fish cover where there was none before. The structure has also helped to improve fishing on this section as many species use the woody debris to escape predators.