Case study:River Wandle: Butter Hill Phase 3

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Location: 51° 22' 13", -0° 9' 36"
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Project overview

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Status Complete
Project web site
Themes Fisheries, Habitat and biodiversity, Social benefits, Urban
Country England
Main contact forename Tim
Main contact surname Longstaff
Main contact user ID
Contact organisation Wandle Trust
Contact organisation web site http://www.wandletrust.org
Partner organisations Environment Agency, Defra, Thames Water, National Lottery's Heritage Lottery Fund
Parent multi-site project

Case_study:Butter Hill restoration project, River Wandle

This is a parent project
encompassing the following
projects
No
Before & After Butter Hill Phase 3 Works © Wandle Trust

Project summary

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This Project is part of a larger scheme with the overall aim of establishing a population of brown trout in the Carshalton arm of the River Wandle for the first time in over 80 years. For more background on this larger scheme, please refer to the parent project "River Wandle Restoration Project".

Flood risk and hydraulic assessment of the weir and fish pass were carried out in conjunction with Matt Horritt Consulting. Works were delivered with the help of appointed contractors Aquamaintain Ltd under the supervision of South East Rivers Trust staff.   The weir at Butter Hill bridge was partially lowered to restore natural flow to the upstream channel and the fish pass modified to improve its efficiency.

Upstream of the weir the over-straight, over-wide channel was narrowed and modified to create a meandering sequence using a combination of gravel, hazel faggots, chestnut posts and coir geotextile with silt from the channel and brash as backfill.   The banks on both sides of the channel were then re-graded to create marginal and transitional habitats. A variety of marginal plant species were introduced to assist with naturalisation by a team of 15 volunteers.

Downstream, for 300 m, channel narrowing and meandering was continued and gravel and Large Woody Debris was introduced along the whole reach to further diversify the river flow and replicate natural hydromorphological processes, creating habitats for invertebrates and all life stages of fish.

Trees were also removed in phases over a two year period to increase light in selected places and encourage plant growth along the whole 500 m reach.

Monitoring surveys and results

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Please see the parent project (River Wandle Restoration Project) for the final results on this work, combined with the other phases.

Lessons learnt

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Catchment and subcatchment

Subcatchment:Wandle


Site

Name Wandle, Butter Hill
WFD water body codes
WFD (national) typology
WFD water body name
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Desired post project morphology
Heavily modified water body No
National/international site designation
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Protected species present No
Invasive species present No
Species of interest
Dominant hydrology
Dominant substrate
River corridor land use
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Project background

Reach length directly affected (m)
Project started 2010/01/01
Works started
Works completed
Project completed 2012/01/01
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Cost for project phases

Phase cost category cost exact (k€) Lead organisation Contact forename Contact surname
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Monitoring



Reasons for river restoration

Mitigation of a pressure
Hydromorphology
Biology Fish: Abundance
Physico-chemical
Other reasons for the project


Measures

Structural measures
Bank/bed modifications Introduction of gravel, Introducing large woody debris, Regrading, Habitat restoration, Restoration of natural vegetation, Tree removal, Weir lowering
Floodplain / River corridor
Planform / Channel pattern Enhancing flow diversity, Improving fish migration, Channel narrowing, Meandering channel
Other
Non-structural measures
Management interventions
Social measures (incl. engagement) Volunteer engagement
Other


Monitoring

Hydromorphological quality elements

Element When monitored Type of monitoring Control site used Result
Before measures After measures Qualitative Quantitative

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Any other monitoring, e.g. social, economic

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Monitoring documents



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Additional links and references

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Supplementary Information

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