Case study:Malltraeth Marsh

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Location: 53° 12' 53.43" N, 4° 19' 42.23" W

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Project overview

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Status	Complete
Project web site
Themes	Habitat and biodiversity
Country	Wales
Main contact forename	Nick
Main contact surname	Elbourne
Main contact user ID
Contact organisation	River Restoration Centre
Contact organisation web site	http://www.therrc.co.uk
Partner organisations
Parent multi-site project
This is a parent project encompassing the following projects	No

Wetland and open water restoration, Malltraeth Marsh.

Project summary

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The channel was canalised, embanked, and virtually featureless carrying highland water from upstream across a flat lowland valley. Marsh either side is grazing land designated as SSSI. Aims of the project: • To restore the open water characteristics of remnant cut-off channels of the Cefni that were being to be lost through drying and reed/rush/sweet-grass invasion. • Combined with local restoration of high water tables, these measures ensured that the wildlife interests which gave rise to its notification as an SSSI are maintained and enhanced. Works carried out: • excavation of drying relic meanders and other open water areas • sluices on drains/ditches to raise water levels in summer • sluices and/or bunds to raise winter water levels • willow/scrub control and other vegetation management • improved bank profiles to the many ditches that traverse the floodplain

Monitoring surveys and results

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Catchment and subcatchment

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Site

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Name	Malltraeth Marsh
WFD water body codes
WFD (national) typology
WFD water body name
Pre-project morphology	Embanked, Straightened
Reference morphology	Wetland marsh
Desired post project morphology
Heavily modified water body	No
National/international site designation	UK - Site of Special Scientific Interest
Local/regional site designations	Special Area of Conservation
Protected species present	No
Invasive species present	No
Species of interest
Dominant hydrology
Dominant substrate
River corridor land use	Wetland, Rough unimproved grassland/pasture
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)	70007,000 m <br />7 km <br />700,000 cm <br />
Project started	1993
Works started
Works completed
Project completed	1996/01/01
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Total cost (k€)
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Cost for project phases

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Reasons for river restoration

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Mitigation of a pressure	Impoundments (not hydropower)
Hydromorphology
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Measures

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Structural measures
Bank/bed modifications	excavation of historic channels, increase bed levels
Floodplain / River corridor	Creation of wetlands, reinstate floodplain
Planform / Channel pattern
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Non-structural measures
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Monitoring

Hydromorphological quality elements

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quality elements

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Any other monitoring, e.g. social, economic

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Supplementary Information

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