Case study:Medmerry Managed Realignment Scheme

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Location: 50° 44' 10.04" N, 0° 48' 42.22" W

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Project overview

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Status	Complete
Project web site	http://https://www.gov.uk/government/publications/medmerry-coastal-flood-defence-scheme/medmerry-coastal-flood-defence-scheme
Themes	Flood risk management, Habitat and biodiversity, Land use management - agriculture, Monitoring, Social benefits
Country	England
Main contact forename	Lee
Main contact surname	Spicer-Howard
Main contact user ID	User:Leespicerhoward
Contact organisation	Environment Agency
Contact organisation web site	http://www.gov.uk/government/organisations/environment-agency
Partner organisations	RSPB
Parent multi-site project
This is a parent project encompassing the following projects	No

Whole Medmerry site aerial view - March 2012

Project summary

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The Environment Agency built major new sea defences between Selsey and Bracklesham in West Sussex. They have developed the Medmerry managed realignment scheme with the help of a wide range of community representatives.

Managed realignment means building new defences inland from the coast and allowing a new ‘intertidal’ area to form seaward of the new defences. ‘Intertidal’ means the land that is exposed at low tide and covered by the sea at high tide.

The scheme will greatly improve the standard of flood protection for over 300 homes, the water treatment works and the main road into Selsey. It will also create important new intertidal wildlife habitat and open up new footpaths, cycleways and bridleways.

Work started in September 2011, and on Monday 4 November, 2013, on one of the highest tides of the year along the south coast, Environment Agency Chairman, Lord Chris Smith, unveiled a plaque to celebrate the completion of the Medmerry flood defence.

Monitoring surveys and results

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Large numbers of birds are already using Medmerry, including wild ducks such as several hundred Teal and Wigeon and there are large roosting flocks of Lapwings. A Harbour Seal has been seen investigating the breach. It will take time for the habitats to develop, but the early signs are very encouraging indeed.

Lessons learnt

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In the 2013-14 winter, the south coast suffered some of the worst weather for 20 years with a sustained period of very high tides, strong winds and stormy seas. The new flood defences have held firm and are working as planned. The shingle beach, which used to be the flood defence, has rolled backwards and has been flattened by the sea. It is important to understand that this was expected and is not a problem.

Image gallery

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Catchment and subcatchment Select a catchment/subcatchment Edit the catchment and subcatchment details (affects all case studies in this subcatchment) Catchment River basin district South East River basin Arun and Western Streams Subcatchment River name Broad Rife Area category Less than 10 km² Area (km2) Maximum altitude category Less than 100 m Maximum altitude (m) 99 m <br />0.009 km <br />900 cm <br /> Dominant geology Siliceous Ecoregion Great Britain Dominant land cover Arable and Horticulture Waterbody ID GB107041006580 Site Edit site Name WFD water body codes WFD (national) typology WFD water body name Pre-project morphology Reference morphology Desired post project morphology Heavily modified water body National/international site designation Local/regional site designations Protected species present Invasive species present 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 Edit project background Reach length directly affected (m) Project started Works started Works completed Project completed Total cost category Total cost (k€) 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 Edit reasons for restoration Mitigation of a pressure Hydromorphology Biology Physico-chemical Other reasons for the project Measures Edit Measures Structural measures Bank/bed modifications Floodplain / River corridor Planform / Channel pattern Other Non-structural measures Management interventions Social measures (incl. engagement) Other Monitoring Hydromorphological quality elements Edit Hydromorphological quality elements Element When monitored Type of monitoring Control site used Result Before measures After measures Qualitative Quantitative Biological quality elements Edit biological quality elements Element When monitored Type of monitoring Control site used Result Before measures After measures Qualitative Quantitative Physico-chemical quality elements Edit 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 Edit Other responses Element When monitored Type of monitoring Control site used Result Before measures After measures Qualitative Quantitative Monitoring documents Upload monitoring documents Additional documents and videos Upload additional documents Additional links and references Edit links and references Link Description http://www.gov.uk/government/publications/medmerry-coastal-flood-defence-scheme/medmerry-coastal-flood-defence-scheme fact sheet http://www.youtube.com/watch?feature=player embedded&v=x7jemyJujg8 YouTube link to medmerry scheme http://https://www.flickr.com/photos/environment-agency/sets/72157631063812816/ Flicker picture Supplementary Information Edit Supplementary Information