Case study:River Quaggy- Chinbrook meadows

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Location: 51° 25' 44", 0° 1' 38"
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Project overview

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Status Complete
Project web site
Themes Habitat and biodiversity, Social benefits, Water quality, Urban
Country England
Main contact forename Dave
Main contact surname Webb
Main contact user ID User:Ascarr
Contact organisation Environment Agency
Contact organisation web site http://www.environment-agency.gov.uk
Partner organisations QWAG, London Borough of Lewisham
Parent multi-site project
This is a parent project
encompassing the following
projects
No
Chinbrook Meadows soon after the works had been completed

Project summary

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This project is an excellent example of a partnership initiative that has not only restored the river and floodplain, but has also paid careful attention to improving the park amenities. The channel work was completed in spring 2002 and by September that year there had already been considerable movement of gravels. Natural geomorphological features including a pool/riffle sequence, gravel bars and steeper banks had formed. The pond has been colonised by invertebrates and the vegetation planted along the banks is now providing good cover in both the planted and unplanted sections.

Site background This section of the River Quaggy, with a flashy flow regime, was channelised and straightened between 1960-1970 as part of a flood alleviation scheme. Prior to restoration it was encased in concrete with fences and high privet hedges near to each bank. It could neither be accessed nor viewed by the public and was devoid of natural fauna and flora.

Objectives To reintroduce the floodplain as a natural flood storage area as part of a larger catchment flood alleviation plan; to enable the River Quaggy to become accessible to the public and hence create a local amenity; to create an environment where native fauna and flora could colonise and allow for natural channel processes.

Design

  • The concrete channel in the park was replaced by a sinuous channel, allowing easy

access. It was (except where the cost of moving existing sewage drains prevented this) cut to follow its path prior to channelisation.

  • Whilst cutting the channel old gravels were evacuated and sufficient ‘room’ was left

along the river corridor to allow for natural adjustment.

  • The margins of the channel were planted using a reputable source of native wetland

plants (including iris, water mint and reeds), a wetland grass and wild flower mix was also sown. One section downstream has not been planted since there was a request from the local group to allow natural colonisation.

  • Flood storage ponds were included in the scheme and at the upstream section a

boardwalk, pond dipping and educational area, were incorporated to attract local school children.

Monitoring surveys and results

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Lessons learnt

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Image gallery


The river Quaggy in Chinbrook meadows before restoration
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Catchment and subcatchment

Catchment

River basin district Thames
River basin London

Subcatchment

River name Quaggy
Area category 10 - 100 km²
Area (km2)
Maximum altitude category 100 - 200 m
Maximum altitude (m) 135
135 m
0.135 km
13,500 cm
Dominant geology Calcareous
Ecoregion Great Britain
Dominant land cover Suburban
Waterbody ID GB106039023290



Other case studies in this subcatchment: Colfes School, Lidl, Manor House Gardens, Manor House Gardens Gauging Station, Manor Park, Mottingham Farm, Quaggy Flood Alleviation Scheme, Quaggy channel improvements, Sutcliffe Park, Sydenham Cottages Nature Reserve


Site

Name River Quaggy
WFD water body codes GB106039023290
WFD (national) typology Calcareous
WFD water body name Quaggy
Pre-project morphology Straight, Revetments
Reference morphology Sinuous
Desired post project morphology
Heavily modified water body Yes
National/international site designation
Local/regional site designations
Protected species present No
Invasive species present No
Species of interest
Dominant hydrology Artificially regulated, Quick run-off
Dominant substrate Bedrock
River corridor land use Urban
Average bankfull channel width category 2 - 5 m
Average bankfull channel width (m)
Average bankfull channel depth category 0.5 - 2 m
Average bankfull channel depth (m)
Mean discharge category
Mean annual discharge (m3/s)
Average channel gradient category
Average channel gradient 0.3
Average unit stream power (W/m2)


Project background

Reach length directly affected (m) 300 m
0.3 km
30,000 cm
Project started 2002/03/01
Works started
Works completed 2002/10/01
Project completed 2002/04/02
Total cost category 50 - 100 k€
Total cost (k€) 100 k€
100,000 €
Benefit to cost ratio
Funding sources Environment Agency

Cost for project phases

Phase cost category cost exact (k€) Lead organisation Contact forename Contact surname
Investigation and design
Stakeholder engagement and communication
Works and works supervision
Post-project management and maintenance
Monitoring



Reasons for river restoration

Mitigation of a pressure Riparian development
Hydromorphology Quantity & dynamics of flow, Channel pattern/planform
Biology Invertebrates, Macrophytes
Physico-chemical Oxygen balance
Other reasons for the project Landscape enhancement, Flood risk management


Measures

Structural measures
Bank/bed modifications Removal of revetments, Introduction of gravel, Planting of native species
Floodplain / River corridor Removal of embankments, Creation of wetland, Creation of pond
Planform / Channel pattern Adding sinuosity
Other
Non-structural measures
Management interventions
Social measures (incl. engagement)
Other Information provision, Consultation


Monitoring

Hydromorphological quality elements

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

Biological quality elements

Element When monitored Type of monitoring Control site used Result
Before measures After measures Qualitative Quantitative
Invertebrates Yes Yes Yes Improvement
Macrophytes Yes Yes Yes Improvement

Physico-chemical quality elements

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

Any other monitoring, e.g. social, economic

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


Monitoring documents



Additional documents and videos


Additional links and references

Link Description
http://www.therrc.co.uk/sites/default/files/projects/p1499.pdf RRC site description
http://www.restorerivers.eu/Publications/tabid/2624/mod/11083/articleType/ArticleView/articleId/3123/Chinbrook-Meadows----A-better-place-to-play.aspx Video on Chinbrook meadows
http://www.qwag.org.uk/quaggy/restoration.php Quaggy Waterways Action Plan link
http://www.lewisham.gov.uk/inmyarea/openspaces/parks/Pages/chinbrook-meadows.aspx Lewisham Council's link
http://en.wikipedia.org/wiki/Chinbrook Meadows Wikipedia link
http://www.greenchain.com/learning/sites/chinbrook-meadows.php Green chain link

Supplementary Information

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