Case study:Emmanuel’s Common Reconnection Project

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Location: 52° 43' 12", 0° 42' 58"
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Project overview

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Status Complete
Project web site
Themes Fisheries, Habitat and biodiversity, Hydromorphology
Country England
Main contact forename Helen
Main contact surname Mandley
Main contact user ID User:JoshRRC
Contact organisation Norfolk Rivers Trust
Contact organisation web site http://www.norfolkriverstrust.org/
Partner organisations
Parent multi-site project
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projects
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Project summary

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The River Nar has been historically modified for human use, changing its channel size and shape, and in places the river’s course. These changes have negatively impacted on the wildlife of the river. The River Nar through Emmanuel’s Common has historically been used for water meadows to graze animals. The river has been deepened and straightened to enable drainage of the site and to increase water flow to power Newton Mill. By looking at historic maps and investigating on the ground you can see the old meandering channel through the woodland.

The project within the common has now been completed. We have delivered the restoration scheme as planned where we wanted to reconnect 600m of old channel constructing one new length of channel to make the meander sequence link up.

The project aims to reconnect the old meandering channel, open up some of the channel by removing scrub to allow light in, improve flow regime, improve fish & invertebrate habitat, and improve aquatic and riparian plant habitat.

Reinstating the old channel by creating a short linking channel upstream and reconnecting the meanders downstream.

The lower channel accounted for 80% of the project time. The available route passed through a slightly raised part of the flood-plain and in the middle reaches it was a challenge to peel away enough ground to make the correct, naturally shallow cross-section. There was little fall to play with too and the main river to which the new channel returned has been dredged and so tuning the gradient proved very tricky. It was worth the effort though. When the flows finally broke through the new channel worked perfectly, with good velocity and no unintentional impoundments.

Monitoring surveys and results

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Please use the link to find out about the Electrofishing surveys for the project http://www.norfolkriverstrust.org/wp-content/uploads/2016/02/Electrofishing-doc.pdf

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Catchment and subcatchment

Catchment

River basin district Anglian
River basin North West Norfolk

Subcatchment

River name Nar
Area category 100 - 1000 km²
Area (km2)
Maximum altitude category Less than 100 m
Maximum altitude (m) 21
21 m
0.021 km
2,100 cm
Dominant geology Calcareous
Ecoregion Great Britain
Dominant land cover Arable and Horticulture
Waterbody ID GB105033047792



Other case studies in this subcatchment: The Pentney Restoration Project


Site

Name
WFD water body codes GB105033047792
WFD (national) typology
WFD water body name Nar DS Blackborough Drain
Pre-project morphology
Reference morphology
Desired post project morphology
Heavily modified water body No
National/international site designation
Local/regional site designations
Protected species present No
Invasive species present No
Species of interest
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Dominant substrate
River corridor land use
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Project background

Reach length directly affected (m)
Project started 2014/06/02
Works started
Works completed
Project completed 2014/11/14
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Cost for project phases

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Reasons for river restoration

Mitigation of a pressure
Hydromorphology Reconnect old channel, improve flow regime
Biology Improve fish habitat and biodiversity
Physico-chemical
Other reasons for the project


Measures

Structural measures
Bank/bed modifications
Floodplain / River corridor Reinstating old channel, Remeandering
Planform / Channel pattern
Other
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Management interventions
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Monitoring

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Monitoring documents



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Supplementary Information

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