Medmerry: managed coastal realignment

Setting and flood risk

Medmerry lies between Selsey and Bracklesham on the West Sussex coast. High tides and storms threatened nearby properties and infrastructure. The former shingle bank required repeated maintenance, making continued defence along the same line costly.

Sources: nationaltrust.org.uk 1 · gov.uk 2

How managed realignment works

The Environment Agency built new defences inland and allowed seawater into land seaward of them. The area between the new bank and the sea became intertidal: covered at high tide and exposed at low tide. Mudflats and saltmarsh create space for tidal water and absorb wave energy.

The scheme combines earth embankments with natural processes. Calling it simply a sea wall would miss the planned change in shoreline and habitat.

Sources: gov.uk 1 · nationaltrust.org.uk 2

Interests and choices

Residents and businesses needed reliable flood protection. The Environment Agency had to fund and maintain defences; conservation partners sought habitat creation. Realignment also changes the use of land and access routes, so agreement with landowners and local communities forms part of the response.

The RSPB manages much of the site as a nature reserve. New walking and cycling access brings recreation and visitors, alongside the flood-management purpose.

Sources: gov.uk 1 · gov.uk 2

Outcomes

The completed scheme provides flood-risk management for homes and infrastructure and created intertidal habitat. Later reporting records breeding birds using the reserve. These are different measures of success: protecting property and creating habitat need separate evidence.

Estimated benefits and visitor totals are useful for appraisal, but they are not guaranteed annual income. The project cost is an upfront sum; the earlier shingle-bank maintenance cost was an annual expenditure.

Sources: nationaltrust.org.uk 1 · gov.uk 2

Evaluation

Managed realignment can suit a coast where there is room to move the defence line inland. Its success depends on land availability, continuing bank maintenance and how the wetland develops. Reduced risk does not mean that future flooding is impossible. Use the dated cost and habitat evidence to justify a judgement for this site.

Sources: nationaltrust.org.uk 1 · gov.uk 2

Using this case in an answer

Explain the coastal risk, how managed realignment changes the defended line, and its effects on people, land use and habitats. Evaluate capital cost, maintenance and continuing flood risk as separate measures.

• Project capital cost and annual maintenance are different measures. Reduced flood risk does not mean zero risk.