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
Parent multi-site project	Case_study:Wensum River Restoration Strategy
This is a parent project encompassing the following projects	No

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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.)

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Catchment and subcatchment Select a catchment/subcatchment 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 Biology Physico-chemical Other reasons for the project Measures Edit Measures Structural measures Bank/bed modifications Floodplain / River corridor Planform / Channel pattern 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 Additional links and references Edit links and references Link Description Supplementary Information Edit Supplementary Information