Case study:River Bure

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Location: 52° 49' 26.61" N, 1° 12' 23.32" E

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Project overview

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Status	Complete
Project web site
Themes	Fisheries, Habitat and biodiversity
Country	England
Main contact forename	Nick
Main contact surname	Elbourne
Main contact user ID	User:NickRRC
Contact organisation	River Restoration Centre
Contact organisation web site
Partner organisations
Parent multi-site project
This is a parent project encompassing the following projects	No

River Bure - following restoration

Project summary

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The National Trust in conjunction with the Blickling fishing club undertook a two-phase restoration project (in 2008 and 2010) at the River Bure, Norfolk. This involved installation of Large Woody Debris (LWD) with the overall aim of improving in-channel and marginal habitats, by re-establishing natural river processes interrupted by past management activities.

The stretch of the Bure flowing through the Blickling Estate had been severely over-widened due to historic dredging to increase channel and holding capacity for several mills in the area. Within the 7 km of river channel that border the Blickling Estate there are four mills and several bypassed meanders. Siltation added to the degraded state of the river, which was heavily wooded.

Felling trees to create in-channel LWD was identified as a good way to increase habitat and restore natural processes to the Bure (historically fallen trees had been removed by the Environment Agency and local fishing club). Riparian habitats were of high quality, comprising ancient woodland and alder and willow carr, therefore restoration works were restricted to options which would have a low impact on the site and surrounding habitats i.e. use of heavy machinery was not advised.

Objectives were:

- To improve river habitat by re-instating woody debris

- To increase the stock of wild brown trout

- To enhance biodiversity and conservation value of the reach

The project was completed in two phases. Phase 1 work was completed in November 2008 over four weeks. There was no allocated budget for the project, so works had to be economical and non-technical as access to the site was limited. Much of the work was therefore based on intuition and what was deemed to be aesthetically “right” for the location. Trees were felled into the channel with some minor modifications made to their in-stream position to comply with EA by-laws and fishing requirements. Work was carried out by volunteers using chainsaws, a hand winch and plastic boat. This phase increased fish catch numbers (based on Blickling fishing club records).

Phase 2 of the project was completed in November 2010, encompassing a baseline survey and monitoring. In this phase the introduction of LWD was more adventurous. Consequently, the results of phase 2 were even more dramatic than phase 1. Effects of restoration appeared to be proportional to the amount of LWD introduced into the river.

The approach at both stages involved adhering to the following:

-selection of trees which were already likely to fall into the channel

-fell them so they remained attached to the root plate

-allow branches to penetrate the river bed to secure the tree

-only if necessary use a stake to prevent movement

-modify the position if necessary to maintain other channel functions e.g. fishing points

-felling more than one tree at each location allows a web of branches and twigs to form, diversifying habitats and anchoring the “structure”

Since 2010 the river has continued to become more diverse in terms of the range of habitats. Sediment trapped by LWD has increase in channel and marginal vegetation. The redistribution of sediments has resulted in a naturally developing channel. Areas of faster flows have begun to clean gravels, with areas of reduced flow velocity causing deposition.

The National Trust has identified an increasing enthusiasm for retaining naturally occurring LWD as part of sustainable river management and restoration since the completion of this project. In the local area request to remove LWD have reduced dramatically. The potential reduction in management costs is likely to encourage LWD to be retained in its natural position or slightly modified as opposed to removed. The River Restoration Centre would like to thank Dave Brady from The National Trust for providing the case study content and photographs.

Monitoring surveys and results

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Lessons learnt

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Catchment and subcatchment

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Subcatchment:Bure

Site

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Name	Bure at Blickling Estate
WFD water body codes
WFD (national) typology
WFD water body name
Pre-project morphology	Over-widened, Over deepened, Straightened
Reference morphology	Sinuous, Pool-riffle
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	Brown trout
Dominant hydrology
Dominant substrate	Gravel, Silt
River corridor land use	Intensive agriculture (arable), Broadleaf/mixed woodland (semi natural)
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

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Reach length directly affected (m)	300300 m <br />0.3 km <br />30,000 cm <br />
Project started	2008/11/01
Works started
Works completed
Project completed	2010/11/01
Total cost category	1 - 10 k€
Total cost (k€)	66 k€ <br />6,000 € <br />
Benefit to cost ratio
Funding sources	The National Trust

Cost for project phases

Reasons for river restoration

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Mitigation of a pressure
Hydromorphology
Biology
Physico-chemical
Other reasons for the project	historic channel widening

Measures

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Structural measures
Bank/bed modifications	Introduction of naturally occuring LWD to encourage flow diversity and increase channel sinuosity
Floodplain / River corridor
Planform / Channel pattern	Allow future natural channel changes to occur, Channel narrowing via the ntroduction of large woody debris
Other
Non-structural measures
Management interventions	no longer remove naturally occuring LWD
Social measures (incl. engagement)
Other