Case study:West Lexham Rehabilitation Project

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Location: 52° 43' 9.81" N, 0° 43' 14.84" E

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Project overview

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Status	Complete
Project web site
Themes	Habitat and biodiversity
Country	England
Main contact forename	Nigel T.H.
Main contact surname	Holmes
Main contact user ID
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Partner organisations	River Restoration Centre, Environment Agency, Norfolk County Council, Natural England
This is a parent project encompassing the following projects

site location of works

Project summary

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A half day work to remove the impounding influence of a weir, and in the channel upstream four pools and runs were dug. A second weir, between two bridges c35m downstream of the one shown in the images, was also removed. This structure had minimal impact on habitat, but was an impediment to easy migration of fish etc. wishing pass upstream.

The structure within the meadow that was impounding the Nar upstream had some archaeological interest. For this reason there was a ‘watching brief’ from Norfolk County Council to ensure there was no damage done to any known existing interest features, and to record anything else of interest should this be revealed during the removal of the impounding structure. To minimise damage to the historical elements of the bridge, the concrete ‘boards’ were removed with great care, leaving the central pillar and upper lintel in place, yet drawing the bed down to the required level.

The effect of centuries of impoundment has been to create a sluggish/non-existent flow in the river upstream with the resultant deposition of thick layers of mud. Pools were created by widening the channel locally. To help keep the pools clear in the future, the channel was narrowed upstream. Due to the extreme depth of soft mud, narrowing was achieved by pushing in one side of the existing river edge with the back of the bucket, and the void created behind this was filled with the arisings from creating the pools. Four pools and upstream ‘runs’ were created, with the run formed upstream of the second pool from the top having a small amount of gravel spread on the bed – this was won from the bed of the river in the pool downstream.

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Catchment and subcatchment

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Catchment

River basin district	Anglian
River basin	North West Norfolk

Subcatchment

River name	Nar
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Site

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Name	West Lexham
WFD water body codes
WFD (national) typology
WFD water body name
Pre-project morphology	Single channel, impounded, straightened
Reference morphology	Single channel, Pool-riffle, Sinuous
Desired post project morphology
Heavily modified water body	No
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Protected species present	No
Invasive species present	No
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Project background

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Project started	2011/02/28
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Project completed	2011/03/04
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Reasons for river restoration

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Mitigation of a pressure
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Measures

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Monitoring

Hydromorphological quality elements

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Image gallery

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River Nar Rehabilitation summary report by Nigel Holmes

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