Case study:Wensum River Restoration Strategy

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Location: 52° 46' 53", 0° 57' 38"
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Project overview

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Status In progress
Project web site http://www.environment-agency.gov.uk/homeandleisure/wildlife/114676.aspx
Themes Fisheries, Flood risk management, Habitat and biodiversity, Hydromorphology, Land use management - agriculture, Monitoring, Water quality
Country England
Main contact forename Adam
Main contact surname Thurtle
Main contact user ID
Contact organisation Environment Agency
Contact organisation web site http://www.environment-agency.gov.uk
Partner organisations Natural England, Water Management Alliance, Riparian Landowners, Atkins
This is a parent project
encompassing the following
projects
Great Ryburgh End Restoration Scheme, Meander reinstatement on the River Wensum at the Ryburgh Loop, River Tat Restoration Scheme, River Wensum Rehabilitation Project - Bintree, River rehabilitation on the River Wensum at Swanton Morley, Sculthorpe Moor Restoration Scheme
Wensum at Great Ryburgh, July 2011 (post-restoration)

Project summary

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The River Wensum Restoration Strategy is a long-term project with the vision to restore all 71km of the River Wensum SSSI/SAC. The project is lead by the Environment Agency, working in partnership with a range of organisations and individuals including Natural England, the Water Management Alliance, Atkins, riparian landowners and anglers. We intend to restore the river and floodplain to a more naturally functioning ecosystem so that it can support the wildlife and fisheries typical of a Norfolk chalk stream. We aim to ensure that the river is sustainably managed to meet the needs of all river users, providing ecosystem services to benefit wildlife, water quality, water resources, flood risk management, agriculture and leisure activities.

The Wensum is a chalk river of great importance for its wildlife, as well as being a notable landscape feature of rural Norfolk. Its conservation interest is recognised nationally and internationally through its notification as a Site of Special Scientific Interest (SSSI) and Special Area of Conservation (SAC). However, the river is in unfavourable ecological condition and failing its Water Framework Directive targets due to past physical modifications for land drainage and milling. In essence parts of the river are too wide, too deep and too straightened, as well as being heavily impounded by mill structures and disconnected from its floodplain by spoil banks resulting from historical dredging.

For the first time we have looked at a whole river scale to see what action needs to be taken to restore each section of the river. The main recommendations of the strategy include narrowing the channel, restoring the gravel bed, reducing impoundment, reconnecting the floodplain, improving channel sinuosity and increasing the amount of large woody material in the channel.

Our over-arching philosophy is to implement integrated schemes that deliver multiple benefits, including river restoration, floodplain biodiversity enhancements, reduced flood risk to people and property, and improved angling and water quality. We work closely with a wide range of other projects and initiatives within the Wensum catchment to achieve these objectives.

As of March 2014 we had completed 6 major restoration schemes on the river. A total of 12.46km of river has been restored.

Monitoring surveys and results

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For each scheme we monitor the impacts of restoration on fish, invertebrates, aquatic macrophytes, and protected species (e.g. water vole). Fixed point photography is also undertaken.

Lessons learnt

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Image gallery


WRS River Tat (Environment Agency)
Wensum Ryburgh Common meander loop (Environment Agency)
Wensum Swanton Morley floodplain re-connection (Environment Agency)
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Catchment and subcatchment

Catchment

River basin district Anglian
River basin Broadland Rivers

Subcatchment

River name Wensum
Area category 10 - 100 km²
Area (km2)
Maximum altitude category Less than 100 m
Maximum altitude (m) 98
98 m
0.098 km
9,800 cm
Dominant geology Calcareous
Ecoregion Great Britain
Dominant land cover Arable and Horticulture
Waterbody ID GB105034051110



Other case studies in this subcatchment: River Wensum Rehabilitation Project - Bintree


Site

Name Bintree
WFD water body codes GB105034051100
WFD (national) typology R19
WFD water body name Wensum
Pre-project morphology Single channel
Reference morphology Single channel
Desired post project morphology
Heavily modified water body Yes
National/international site designation EU - Special Area of Conservation
Local/regional site designations
Protected species present No
Invasive species present No
Species of interest
Dominant hydrology Groundwater
Dominant substrate Gravel
River corridor land use Intensive agriculture
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
Average unit stream power (W/m2)


Project background

Reach length directly affected (m)
Project started 2000/08/01
Works started
Works completed 2000/10/01
Project completed
Total cost category 50 - 100 k€
Total cost (k€) 73 k€
73,000 €
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 Environment Agency Simon Johnson
Stakeholder engagement and communication
Works and works supervision Environment Agency Rob Dryden
Post-project management and maintenance
Monitoring



Reasons for river restoration

Mitigation of a pressure Agriculture, Land drainage
Hydromorphology Channel pattern/planform, Quantity & dynamics of flow, Connection to groundwaters
Biology Invertebrates: Taxonomic composition
Physico-chemical
Other reasons for the project Landscape enhancement, Flood risk management


Measures

Structural measures
Bank/bed modifications Bed raising
Floodplain / River corridor
Planform / Channel pattern Channel narrowing
Other
Non-structural measures
Management interventions
Social measures (incl. engagement)
Other Participation in maintenance


Monitoring

Hydromorphological quality elements

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

Element When monitored Type of monitoring Control site used Result
Before measures After measures Qualitative Quantitative
Invertebrates: Taxonomic composition Yes Yes

Physico-chemical 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

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.norfolk.gov.uk/view/ncc089250 RWRS fact sheet
http://www.wensumalliance.org.uk/publications/Wensum restoration.pdf River Wensum restoration strategy 2009 Natural England
http://www.youtube.com/watch?v=-oigsbVY22M Three minute video produced for the 2014 England River Prize

Supplementary Information

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