Case study:River Marden at Calne

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Location: 51° 26' 17", -2° 0' 15"
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Project overview

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Status Complete
Project web site
Themes Flood risk management, Habitat and biodiversity, Social benefits
Country England
Main contact forename Paul
Main contact surname Jolliffe
Main contact user ID
Contact organisation Nicholas Pearson Associates
Contact organisation web site http://www.npaconsult.co.uk/
Partner organisations
Parent multi-site project
This is a parent project
encompassing the following
projects
No
Plan of restored reach

Project summary

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Following the demolition of a town centre factory, the River Marden through Calne flowed in a straight concrete channel and two small weirs barred the passage of fish. Urban regeneration, and the resultant redevelopment of the site, meant that the river had to be diverted south of its existing course and the opportunity was taken to improve the character of the river and create a public amenity.

The diversion was undertaken in the form of a double meander so that natural geomorphological features such as shoals, riffles and pools could be incorporated, along with public access to the river and the creation of a variety of sustainable, attractive habitats for flora and fauna.

The scheme has been a success and the river is now a focal point of the town and the centerpiece for the towns annual duck race!

Monitoring surveys and results

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Lessons learnt

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Image gallery


River Marden before restoration looking downstream
River Marden before restoration looking upstream
Re-meandered channel and riverside access - 2012
Scheme holding up well in floods - 2012
Calne charity duck race - 2007
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Catchment and subcatchment

Catchment

River basin district Severn
River basin Bristol Avon and North Somerset Streams

Subcatchment

River name R Marden - conf Abberd Bk to conf unnamed trib
Area category 10 - 100 km²
Area (km2)
Maximum altitude category 100 - 200 m
Maximum altitude (m) 114
114 m
0.114 km
11,400 cm
Dominant geology Calcareous
Ecoregion Great Britain
Dominant land cover Arable and Horticulture
Waterbody ID GB109053022060



Site

Name River Marden at Calne
WFD water body codes GB109053022060
WFD (national) typology
WFD water body name R Marden - conf Abberd Bk to conf unnamed trib
Pre-project morphology Straightened, Artificial bed
Reference morphology Bedrock cascade, 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
Dominant substrate Chalk
River corridor land use Urban
Average bankfull channel width category
Average bankfull channel width (m)
Average bankfull channel depth category
Average bankfull channel depth (m)
Mean discharge category
Mean annual discharge (m3/s)
Average channel gradient category
Average channel gradient
Average unit stream power (W/m2)


Project background

Reach length directly affected (m) 100
100 m
0.1 km
10,000 cm
Project started 1999/03/01
Works started
Works completed
Project completed 1999/09/30
Total cost category
Total cost (k€)
Benefit to cost ratio
Funding sources

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

Supplementary funding information

Exact costs for the project are not available but would have been "considerable" given the works required



Reasons for river restoration

Mitigation of a pressure Urbanisation
Hydromorphology Channel pattern/planform, Quantity & dynamics of flow
Biology Fish
Physico-chemical
Other reasons for the project Community demand, access to the river, urban regeneration/development


Measures

Structural measures
Bank/bed modifications Bedrock cascades and outcrops, Creation of pools and riffles, Creation of shoals/berms, Weir removal
Floodplain / River corridor Public access to the river
Planform / Channel pattern Re-meandering
Other Replacement existing culvert with twin culvert
Non-structural measures
Management interventions
Social measures (incl. engagement) Improved public access, Focal point for local events
Other


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
Fish No Yes Yes No No 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/pdf/manual/MAN 1 5.pdf RRC Manual of River Restoration Techniques entry - Creation of meandering channel and replacement of concrete weirs
http://www.therrc.co.uk/pdf/manual/MAN 5 4.pdf RRC Manual of River Restoration Techniques entry - Installation of simulated bedrock outcrops
http://www.therrc.co.uk/pdf/manual/MAN 8 5.pdf RRC Manual of River Restoration Techniques entry - Urban riverside access

Supplementary Information

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