Case study:Southington River Restoration Project

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Location: 51° 14' 41.51" N, 1° 16' 16.57" W
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Project overview

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Status Complete
Project web site
Themes Economic aspects, Environmental flows and water resources, Fisheries, Flood risk management, Habitat and biodiversity, Spatial planning, Urban
Country England
Main contact forename Heb
Main contact surname Leman
Main contact user ID
Contact organisation Environment Agency SSD
Contact organisation web site http://.gov.uk
Partner organisations Natural England
This is a parent project
encompassing the following
projects
Image showing location of removed structure and newly improved surrounding area

Project summary

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Removal of a historic impounding structure on the River Test at Overton and the restoration of 400m of channel upstream. The reach include x2 crescent rock ramps to retain the head and spread it over a longer distance.

Monitoring surveys and results

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There was no official monitoring at this site.

Lessons learnt

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No real lessons. Just make sure you get it right before you start.


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Catchment and subcatchment



Site

Name River Test
WFD water body codes
WFD (national) typology
WFD water body name
Pre-project morphology
Reference morphology
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) 400m0.4 km <br />40,000 cm <br />
Project started 2017/06/01
Works started 2017/09/20
Works completed 2017/12/21
Project completed 2017/12/21
Total cost category 50 - 100 k€
Total cost (k€)
Benefit to cost ratio
Funding sources Test and Itchen River Restoration Strategy, Landowner

Cost for project phases

Phase cost category cost exact (k€) Lead organisation Contact forename Contact surname
Investigation and design
Stakeholder engagement and communication 50 - 100 k€ Environment Agency Heb Leman
Works and works supervision Environment Agency Heb Leman
Post-project management and maintenance
Monitoring



Reasons for river restoration

Mitigation of a pressure The River Test is one of the best examples of a Chalk River in England supporting diverse plant and wildlife species. As such, it is designated a Site of Special Scientific Interest (SSSI).
Hydromorphology
Biology
Physico-chemical
Other reasons for the project


Measures

Structural measures
Bank/bed modifications This project took place on the River Test at Overton, Hampshire (SU50953 49769) in autumn of 2017. The report by Atkins in 2012 identified this stretch as needing restoration. The report had broken the river into reaches. Each numbered reach had the problems associated with that reach and the restoration actions needed to restore it. In the case of reach T009 an historic structure was impounding several hundred metres of channel to the detriment of the SSSI. The aims of the project were to improve 400m of river, restore the reach from a silty canal to a naturally flowing channel and provide fish passage by removing the structure while at the same time being sympathetic to the history of the site.
Floodplain / River corridor
Planform / Channel pattern
Other
Non-structural measures
Management interventions
Social measures (incl. engagement) One of the most enjoyable parts of this restoration was working with and involving the local community. This came about because of the experiences gained in 2016. In 2016 given the location of the restoration through Overton village the owner and contractor where advised to let as many people know about the project so they knew what was happening. While this instruction was carried out many local people where still shocked as to the scale of works. Many non-indigenous tree where felled to allow light into a previously over shaded channel and consequently the view for many locals changed dramatically. Following local concerns Heb Leman the Project Officer gave a presentation to the local community on the background to the Strategy and consequently why the works where being carried out. After this the local community embraced what was being done and wanted to be informed of any future works. Once the landowner had agreed to continue the works upstream in 2017 and remove the structure a guided tour was arranged for residents. This showed them the already beneficial changes to the restored channel and informed them of what was going to happen in 2017. To involve them further it was decided that the Overton Biodiversity Society would carry out the water vole surveys prior to the work and that the community would be kept informed of the new works via the community Face Book page. The landowner also agreed that because of the historic and archaeological interest in the site that Overton Archaeological Society could also carry out a dig during the works. Consequently throughout the works local archaeologist worked alongside County archaeologist piecing together the history of the site. On completion of the works all the finds and the long history of the site where presented to the local community through an evening of presentations on the restoration itself and the history of the site. This event was attended by at least 120 people and was very well received. From this also came further potential restoration works with others wanting to be involved. The whole experience also engaged the wider community with the landowner for the benefit of all. Other external inputs came from colleagues specialising in fish passage. This was a technically challenging project and the finished project had to enable up and downstream fish passage. Their knowledge was invaluable in allowing this happen.
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



Additional documents and videos


Additional links and references

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Supplementary Information

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