Case study:River Wensum Restoration, Reach 10 Lenwade

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Location: 52° 43' 29.97" N, 1° 7' 10.46" E

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Project overview

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Status	Complete
Project web site
Themes	Habitat and biodiversity, Hydromorphology
Country	England
Main contact forename	Amy
Main contact surname	Butcher
Main contact user ID	User:Amy.butcher
Contact organisation	Environment Agency
Contact organisation web site	http://www.gov.uk/environment-agency
Partner organisations	Natural England
Parent multi-site project	Case_study:Wensum River Restoration Strategy
This is a parent project encompassing the following projects	No

Project picture

Project summary

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Reach 10 of the River Wensum Restoration Strategy involved restoring 1.3km of SSSI & SAC designated river at Lenwade, west of Norwich, Norfolk. Improvements to morphological diversity were achieved here through the installation of woody material features, bank stabilisation, hinging willow trees and re-engineering the existing gravel bed to create riffles and pools. Selective tree felling also took place to allow light into a heavily shaded area of the channel.

Monitoring surveys and results

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Analysis of monitoring results pending.

Lessons learnt

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Access was very limited due to the presences of fishing lakes adjacent to the river. Most works had to be completed by hand. Some work was carried out by amphibious excavator where the benefits outweighed the potential damage to the gravel bed from the excavator tracks.

Additional tree works were required due to periods of high winds and the need to make the area safe for construction work to be carried out. Re-profiled river banks with bare soil were exposed during high flows and could have lead to erosion and sediment input. Seeding and the installation of a biodegradable jute matting was carried out to minimise erosion.

(This had not been anticipated in the design. Ideally work would be carried out early enough to allow bank vegetation to re-establish from the existing seed bank.)

Image gallery

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Catchment and subcatchment Select a catchment/subcatchment Edit the catchment and subcatchment details (affects all case studies in this subcatchment) Catchment River basin district Anglian River basin Broadland Rivers Subcatchment River name Wensum US Norwich Area category 100 - 1000 km² Area (km2) Maximum altitude category Less than 100 m Maximum altitude (m) 9898 m <br />0.098 km <br />9,800 cm <br /> Dominant geology Calcareous Ecoregion Great Britain Dominant land cover Arable and Horticulture Waterbody ID GB105034055881 Other case studies in this subcatchment: Great Ryburgh End Restoration Scheme, Meander reinstatement on the River Wensum at the Ryburgh Loop, River Wensum Restoration, Reach 3a Costessey, River Wensum Restoration, Reach 9 Attlebridge, River rehabilitation on the River Wensum at Swanton Morley, Sculthorpe Moor Restoration Scheme, Wensum River Restoration and Floodplain Enhancement, Wensum River Restoration and Floodplain Enhancement, Pensthorpe Site Edit site Name WFD water body codes WFD (national) typology WFD water body name Pre-project morphology Reference morphology Desired post project morphology Heavily modified water body National/international site designation Local/regional site designations Protected species present Invasive species present Species of interest Dominant hydrology Dominant substrate River corridor land use 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 Edit project background Reach length directly affected (m) Project started Works started Works completed Project completed 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 Reasons for river restoration Edit reasons for restoration Mitigation of a pressure Hydromorphology Channel pattern/planform, Width & depth variation, Flow velocities Biology Physico-chemical Other reasons for the project Measures Edit Measures Structural measures Bank/bed modifications Bank reprofiling, Bank stabilisation, Bed reprofiling Floodplain / River corridor Tree management Planform / Channel pattern Brushwood berms to increase scour on the gravels, Introducing large woody debris Other Non-structural measures Management interventions Social measures (incl. engagement) Other Monitoring Hydromorphological quality elements Edit Hydromorphological quality elements Element When monitored Type of monitoring Control site used Result Before measures After measures Qualitative Quantitative Biological quality elements Edit biological quality elements Element When monitored Type of monitoring Control site used Result Before measures After measures Qualitative Quantitative Physico-chemical quality elements Edit 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 Edit Other responses Element When monitored Type of monitoring Control site used Result Before measures After measures Qualitative Quantitative Monitoring documents Upload monitoring documents Additional documents and videos Upload additional documents RWRS Fact Sheet 9 -Lenwade.pdf Additional links and references Edit links and references Link Description Supplementary Information Edit Supplementary Information