Wansford Bridge to Snakeholme
This 1.5km section of the West Beck has been identified as being over wide, has compacted gravels, silt beds, lack of in-stream flow diversity and cover for invertebrates, fish and mammals. Although the site has some vertical banks that are stable and provide habitat for kingfishers other sections need support from erosion at times of high flows.
This project used a wide range of ‘green engineering’ techniques to address these issues and improve the overall biodiversity of the project site.
1. Removed encroaching glyceria margin and established a diverse plant community to benefit nectar insects and provide a seed bank at the top of this project site.
2. A stone groyne installed in the late ‘80s was removed. The stones were used as revetment along with willow material on a piled bend where existing piles have been exposed.
3. Large woody debris on site was placed into the channel and secured.
4. Some unstable bank side trees and bushes were hinged and secured into the channel to create cover for mammals and fish and increase flow diversity.
5. Several large willows on site were in danger of being lost through wind damage. The trees were surveyed and where necessary, the timber was used to create flow deflectors along the project site.
6. Created protection of a friable bank from further damage.
The margin was sprayed off using an approved herbicide. The effectiveness of this late application will be assessed during the summer and a decision made on a way forward.
Removal of the stone weir was undertaken and the stones and silt have been placed behind the nearby bank revetment. The new line of the bank was marked by pressing in posts where the willow spiling will be woven.
Large Wooded Debris (LWD) was inserted into the new bank line to enhance flow diveristy. The logs were securely pinned to the river bed. Once filled, the friable soil was protected by using a coir geotextile. The area will be allowed to decolonise with natural plant species
Removal of dangerous limbs from a riverside tree. These limbs were used as in-channel habitat and securely pinned to the riverbed. Small course material from these limbs was used to protect the ‘toe’ of vertical banks and provide habitat for voles, fry and kingfishers.
The image above shows a section at the lower end of the site where a large silted margin had encroached into the channel causing a massive erosion problem to the bank on the left. It was originally planned to create a secondary channel into the right of the frame in an attempt to encourage the river to flow around the outside of the bend and prevent further settlement of sediment. As the channel creation started it became apparent that the material was too friable to stand as an island. It was agreed that all the sediment would be removed and the banks stabilised by using willow material gained from the tree thinning. Several large bushes were hinged into the channel and secured to the bank. This will create in stream cover for fry and invertebrates and nesting sites for water fowl.
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