Case study:Salisbury Avon Restoration Project

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Location: 51° 3' 41.42" N, 1° 48' 1.15" W
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Project overview

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Status In progress
Project web site
Themes Habitat and biodiversity, Hydromorphology
Country England
Main contact forename John
Main contact surname Rattray
Main contact user ID
Contact organisation Wiltshire Wildlife Trust
Contact organisation web site http://www.wiltshirewildlife.org
Partner organisations Environment Agency, Natural England, Wessex Water, Wiltshire Fishery Association
This is a parent project
encompassing the following
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Project summary

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The Hampshire Avon has historically been dredged, over-widened and impounded in many places due to past river management. This has led to a reduction in the river’s geomorphological processes, which has, in turn, led to a decline in the habitat quality and quantity throughout the reach. This decline, despite recent sympathetic management, has continued due to the lack of variation in channel form and flows, as well as riparian land use.

Description of Works This project focuses on two 750m reaches of the Hampshire Avon at Figheldean and West Amesbury, identified in the Strategic Framework for the Restoration of the River Avon (SFfRRA) as being in need of restoration for habitat quality. The restoration aims to return a more natural flow regime at the two sites, in order to promote natural bed scouring and increase riparian habitat for a variety of organisms. This will be achieved through:

  • the narrowing of over-widened channels to promote bed scouring and increase Ranunculus growth;
  • re-meandering of channelized sections, through the creation of berms and the use of woody debris, to restore natural deposition/erosion processes;
  • introduction of woody debris to aid channel narrowing and create in-channel habitat for fish and invertebrates;
  • creation of gravel riffles to create fish spawning habitat and flow variation;
  • tree planting for channel shading and to provide future woody debris;
  • riparian habitat creation/enhancement, such as scrape creation for invertebrate and bird life and bank re-profiling to reconnect the river to the floodplain (re-wetting wet woodland/pasture).

Each restoration project completed will act as an example to future projects in the area. Through appropriate publi-cation and engagement this project will help to raise awareness of river restoration techniques and implementation on the River Avon catchment. Restoring natural functions to the river system will also increase the potential of the river to adapt to a changing climate in the future as part of a living landscape.

Monitoring surveys and results

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Catchment and subcatchment

Catchment

River basin district South West
River basin Hampshire Avon

Subcatchment

River name Hampshire Avon (Lower)
Area category 1000 - 10000 km²
Area (km2)
Maximum altitude category 100 - 200 m
Maximum altitude (m) 152152 m <br />0.152 km <br />15,200 cm <br />
Dominant geology Calcareous
Ecoregion Great Britain
Dominant land cover Improved grassland
Waterbody ID GB108043015840



Other case studies in this subcatchment: River Avon Stream project, Salmonid, coarse fish and wetland bird habitat and flood plain linkage project, Hampshire Avon, Strategic Framework for Restoration of the River Avon (SFfRRA)


Site

Name Hampshire Avon
WFD water body codes GB108043015840
WFD (national) typology
WFD water body name
Pre-project morphology
Reference morphology Actively meandering
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
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

Reach length directly affected (m)
Project started
Works started
Works completed
Project completed
Total cost category 100 - 500 k€
Total cost (k€) 286.470286.47 k€ <br />286,470 € <br />
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

Mitigation of a pressure
Hydromorphology Structure & condition of riparian zone, Width & depth variation, Freshwater flow regime, Flow velocities
Biology
Physico-chemical
Other reasons for the project Climate change mitigation, Socio-Economic


Measures

Structural measures
Bank/bed modifications Creation of gravel riffles to create fish spawning habitat and flow variation
Floodplain / River corridor Tree planting for channel shading and to provide future woody debris
Planform / Channel pattern Re-meandering of channelized sections, through the creation of berms and the use of woody debris, to restore natural deposition/erosion processes; the narrowing of over-widened channels to promote bed scouring and increase Ranunculus growth.
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

Biological quality elements

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

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


Monitoring documents




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Supplementary Information

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