Case study:River Avon at East Chisenbury

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Location: 51° 16' 12", -1° 48' 32"
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Project overview

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Status Complete
Project web site
Themes Flood risk management, Habitat and biodiversity, Monitoring, Social benefits, Spatial planning
Country England
Main contact forename John
Main contact surname Rattray
Main contact user ID
Contact organisation Wessex Chalkstreams Project
Contact organisation web site http://www.wiltshirewildlife.org/what-we-do/wessexchalksstreams
Partner organisations Wiltshire Chalk Streams, Environment Agency, Wessex Water, Natural England, Wiltshire Wildlife Trust, Chisenbury Fishing Syndicate, Cain Bio-Engineering Ltd
Parent multi-site project

Case_study:River Avon Stream project

This is a parent project
encompassing the following
projects
No
Restored channel - berm feature installed to narrow channel. Courtesy of the River Restoration Centre.

Project summary

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The River Avon and its major tributaries are recognised as a Special Area of Conservation for their rare habitats and species, including flowing water vegetation (eg. ranunculus and water-crowfoot), Atlantic salmon, Bullhead, brook and sea lamprey, water vole and otter.

The restoration project at East Chisenbury is part of the Wessex Chalk Streams PRoject (WCSP), which began in 1999 - a partnership between the Wiltshire Wildlife Trust, Natural England, the Environment Agency, Wessex Water and the Wiltshire Fishery Association. the project is focused on restoring river and wetland habitat, while helping to achieve targets under the Wiltshire & Swindon and Wessex Water Biodiversity Action Plans (BAPs).

The project at East Chisenbury was completed in two phases:

  • Phase 1 (2005): Trial project to restore a 70m reach below Compton Bridge which had been subject to heavy dredging - Total Cost: £30,000.
  • Phase 2 (2009): Restoration of a 650m reach upstream of Compton Bridge. Involved use of successful 'coir net' technique to re-introduce sinuosity and hydromorphological function to the overwide channel.


  • Further information regarding aims, objectives, project successes and pre/post restoration project photos are available in the attached Wessex Chalk Streams Project report (see bottom of page).

Monitoring surveys and results

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Lessons learnt

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Catchment and subcatchment

Catchment

River basin district South West
River basin Hampshire Avon

Subcatchment

River name Hampshire Avon (Upper)
Area category 100 - 1000 km²
Area (km2)
Maximum altitude category 200 - 500 m
Maximum altitude (m) 212
212 m
0.212 km
21,200 cm
Dominant geology Calcareous
Ecoregion Great Britain
Dominant land cover Arable and Horticulture
Waterbody ID GB108043022350



Other case studies in this subcatchment: Gunville Phase I, Longstreet A 91a, River Avon Habitat Enhancement, Fifield, West Amesbury


Site

Name East Chisenbury
WFD water body codes GB108043022350
WFD (national) typology Low, Medium, Calcareous
WFD water body name Hampshire Avon (East)
Pre-project morphology High width:depth, Single channel
Reference morphology Sinuous, Pool-riffle
Desired post project morphology
Heavily modified water body Yes
National/international site designation EU - Special Area of Conservation
Local/regional site designations SSSI (Site of Special Scientific Interest)
Protected species present No
Invasive species present No
Species of interest
Dominant hydrology Quick run-off, Groundwater
Dominant substrate Gravel
River corridor land use Extensive agriculture, Urban
Average bankfull channel width category 5 - 10 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) 720 m
0.72 km
72,000 cm
Project started 2005/01/01
Works started 2006/01/01
Works completed 2009/01/01
Project completed
Total cost category 100 - 500 k€
Total cost (k€) 120 k€
120,000 €
Benefit to cost ratio
Funding sources Wessex Chalk Streams Project, Environment Agency

Cost for project phases

Phase cost category cost exact (k€) Lead organisation Contact forename Contact surname
Investigation and design Environment Agency
Stakeholder engagement and communication Environment Agency
Works and works supervision Environment Agency
Post-project management and maintenance
Monitoring



Reasons for river restoration

Mitigation of a pressure Flood defence
Hydromorphology Width & depth variation, Flow velocities, Substrate conditions, Channel pattern/planform
Biology Fish: Abundance, Invertebrates: Abundance, Macrophytes
Physico-chemical
Other reasons for the project Bank erosion, Habitat enhancement


Measures

Structural measures
Bank/bed modifications Deflectors, Tree management, Bed raising, Marginal planting, Introducing large woody debris
Floodplain / River corridor Reconnection to the riparian zone
Planform / Channel pattern Creation of wooden deflectors, Channel narrowing
Other
Non-structural measures
Management interventions
Social measures (incl. engagement)
Other


Monitoring

Hydromorphological quality elements

Element When monitored Type of monitoring Control site used Result
Before measures After measures Qualitative Quantitative
Width & depth variation Yes Yes Improvement
Flow velocities Yes Yes Improvement
Substrate conditions Yes Yes Improvement

Biological quality elements

Element When monitored Type of monitoring Control site used Result
Before measures After measures Qualitative Quantitative
Fish: Abundance Yes Yes Yes Improvement
Macrophytes Yes Yes Yes Improvement
Invertebrates: Abundance Yes Yes Yes Improvement

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

Element When monitored Type of monitoring Control site used Result
Before measures After measures Qualitative Quantitative
Public use Yes Yes Improvement


Monitoring documents



Additional documents and videos



Additional links and references

Link Description
http://publications.environment-agency.gov.uk/pdf/GESW0910BSTR-E-E.pdf WFD Status for Hampshire Avon (Middle) - See P. 1308.
http://www.youtube.com/watch?v=4goBfNnmS4s Youtube Video: Wessex Chalk Streams Project
http://www.cainbioengineering.co.uk/case-studies/river-case-study-river-restoration-chisenbury-phase-i/ Cain Bio-Engineering Ltd - Case Study Phase I
http://www.cainbioengineering.co.uk/case-studies/river-case-study-river-restoration-east-chisenbury/ Cain Bio-Engineering Ltd - Case Study Phase II

Supplementary Information

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