Case study:Spring Meadow Meander Restoration

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Location: 50° 59' 57", -0° 0' 29"
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Project overview

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Status Complete
Project web site http://www.oart.org.uk/projects/morph-sheffield-park.htm
Themes Fisheries, Flood risk management, Habitat and biodiversity, Hydromorphology, Monitoring
Country England
Main contact forename Peter
Main contact surname King
Main contact user ID
Contact organisation Ouse and Adur Rivers Trust
Contact organisation web site http://www.oart.org.uk/
Partner organisations Environment Agency, Royal HaskoningDHV, C A Blackwell
Parent multi-site project

Case_study:The Middle Ouse Restoration of Physical Habitats (MORPH)

This is a parent project
encompassing the following
projects
No
Restored meander eighteen months after project works finished, looking upstream © RRC, July 2014

Project summary

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The Sussex River Ouse near Slaugham, West Sussex has historically been managed for navigation. These works have straightened the channel, increasing the width and depth in many places. The Spring meadow site is on the north eastern bank of the river at Sheffield Park, within the High Weald Area of Outstanding Natural Beauty (AONB). The site was acquired by the current landowner to increase wildlife value in the area. Since conception in 2010, works on site were finished in 16 weeks and the project was completed in 2012. Initially it had been hoped to complete works in 8 weeks, however heavy rainfall caused a relatively short delay.


The Sheffield Park Meanders project involved the reinstatement of the historic meandering course of the Ouse at spring meadow to achieve the following aims:

• Reinstate the historic course of the river through the re-excavation of the visible meander. The creation of a meandering channel allows a greater diversity of habitats to develop, specifically for multiple fish species.

• Reduce flood risk by creating a longer meandering channel length, which slows the flow of water heading downstream. At the same time the new bank profiling aimed to encourage natural functioning of the floodplain.

• The incorporation of a low flow channel which maintains sufficient water depth for fish migration in all flow conditions.

• Restoration of existing wet meadow habitats at the site and creation of new woodland areas.


Initially a 20 meter trial area was excavated, allowing adjustments to be made on expert on site recommendation. Banks were roughened up with a toothed bucket to ensure an undulating bank profile. Spoil from excavation was spread across a railway embankment close by to reduce the cost of disposal.

The project was named the Professional category winner at the annual Wild Trout Trust (WTT) Conservation Awards 2013. The panel comprised two experts, Paul Gaskell (WTT) and Dr. Jenny Mant from the River Restoration Centre.

The project is one of thirteen projects within the Middle Ouse Restoration of Physical Habitats (MORPH) project; led by the Environment Agency in partnership with the Ouse & Adur Rivers Trust (OART) & supported by Royal HaskoningDHV (design, engineering and environmental consultancy services) and C A Blackwell (contractor for the implementation works). Each of these projects is being considered individually but also in terms of how they will work in conjunction with each other to improve the diversity of the river and reduce flood risk.


Several details were built into the design to meet the site specific requirements. A ford was constructed to give access to a newly created island area in the centre of the channel. Woody material was added to the new channel at five locations to encourage flow diversity and provide the channel with some shade. The existing channel and new meandering course are joined via a bund constructed at the upstream confluence of the two channels. At normal flow levels this directs all the flow down the mender, leaving the old course as a backwater. In times of flood the bund can be overtopped, allowing water to flow down both channels, increasing local flood capacity.

The land surrounding the site is in Higher Level Stewardship scheme for floodplain hay meadow. The island at the centre of the site was no longer manageable as a hay meadow, therefore a Forestry Commission Woodland Creation Grant was approved to create 1.5Ha of floodplain woodland. This area would slow the flow of flood waters, help to trap sediment and increase biodiversity of the site. Promotion of the project included coverage on BBC South East today programme, local papers and area group websites.

Monitoring surveys and results

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Working with University of Brighton, the project has set up a long term monitoring programme to look at and assess geomorphological changes, seed dispersal of Himalayan Balsam, and hay meadow restoration techniques.

Lessons learnt

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The design of the new two-stage channel (incorporating a low flow channel) has increased water depth during low flows. In combination with a greater variety of channel widths and depths, this has increased habitat diversity which should benefit fish populations.

Within a year of the project works, native vegetation had begun to establish on the banks. This will provide shelter and feeding areas for fish during high flows and will increase habitat for invertebrate species such as dragonflies, beetles and fly species.

The newly created backwater will provide refuge for juveile fish, create warmer conditions and shallow refugia as nursey areas for young amphibians and invertebrates which live in still water. The introduction of woody material provides shelter during low flows and marginal shelves will become vegetated and provide areas for feeding and resting.

Out of channel habitat enhancement of floodplain woodland and additional lateral connectivity is expected to lead to improvements in the biodiversity value of the landscape (wet meadow habitats are nationally rare) & reduce flood risk downstream by increasing capacity for floodwaters.

The public have been consulted and kept informed of progress throughout the project, building local support for river restoration and its associated benefits.


Image gallery


Upstream part of the project where Himalayan Balsam will need to be managed - © Nick Elbourne (RRC), October 2013
Re-instated meander, looking downstream - © Nick Elbourne (RRC), October 2013
Constructed river crossing (Ford) - © Nick Elbourne (RRC), October 2013
River Ouse at Sheffield Park/Spring Meadow post restoration © Royal HaskoningDHV
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Catchment and subcatchment

Catchment

River basin district South East
River basin Adur and Ouse

Subcatchment

River name Ouse from Cockhaise Brook confluence to Spithurst
Area category 100 - 1000 km²
Area (km2)
Maximum altitude category 100 - 200 m
Maximum altitude (m) 161
161 m
0.161 km
16,100 cm
Dominant geology Siliceous
Ecoregion Great Britain
Dominant land cover Improved grassland
Waterbody ID GB107041012710



Other case studies in this subcatchment: River Ouse at Sharpsbridge Rock Ramp Fish Easement Project


Site

Name River Ouse at Sheffield Green
WFD water body codes GB107041012710
WFD (national) typology Low, Medium, Siliceous
WFD water body name Ouse from Cockhaise Brook confluence to Spithurst
Pre-project morphology Trapezoidal, Impounded, Over-widened, Uniform bed
Reference morphology 2-stage channel
Desired post project morphology Width and depth variation, 2-stage channel
Heavily modified water body Yes
National/international site designation
Local/regional site designations
Protected species present No
Invasive species present Yes
Species of interest Himalayan balsam (Impatiens glandulifera )
Dominant hydrology
Dominant substrate
River corridor land use Wet meadow, Rough unimproved grassland/pasture, Woodland
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) 400
400 m
0.4 km
40,000 cm
Project started
Works started 2012/09/01
Works completed 2012/12/24
Project completed
Total cost category 100 - 500 k€
Total cost (k€) 150
150 k€
150,000 €
Benefit to cost ratio
Funding sources Defra

Cost for project phases

Phase cost category cost exact (k€) Lead organisation Contact forename Contact surname
Investigation and design Royal HaskoningDHV Ian Dennis
Stakeholder engagement and communication Ouse and Adur Rivers Trust Peter King
Works and works supervision Ouse and Adur Rivers Trust Peter King
Post-project management and maintenance Ouse and Adur Rivers Trust Peter King
Monitoring University of Brighton



Reasons for river restoration

Mitigation of a pressure Barriers to fish migration
Hydromorphology Quantity & dynamics of flow
Biology Fish: Abundance, Fish: Species composition, Invertebrates: Abundance, Invertebrates: Diversity
Physico-chemical
Other reasons for the project Landscape enhancement


Measures

Structural measures
Bank/bed modifications Alteration in channel dimensions, Bank improvement, Improvement of natural flows, Introducing large woody debris
Floodplain / River corridor Creation of wet woodland
Planform / Channel pattern Improvement of channel morphology, Meandering channel
Other
Non-structural measures
Management interventions Monitoring strategy
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 No Yes No No No Awaiting results

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
Seed dispersal of Himalayan Balsam No Yes No No No Awaiting results


Monitoring documents



Additional documents and videos


Additional links and references

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Supplementary Information

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