Adapting to coastal change: minsmere flood risk management

1. Adapting to coastal change: minsmere flood risk management Alex schofield Project manager, Maritime & Coastal schofielda@bv.com

2. Outline of presentation Project background Existing defences Coastal change Options “long list” to preferred option Preferred option Environmental and social mitigation Constructed scheme Community involvement Future management

3. Project background Parties involved: • Client: Environment Agency • Consultant: Black & Veatch Ltd • Contractor: Interserve • ECC PM: Royal Haskoning • Landowner: Timeline: • B&V first got involved in 2001 (!) • Urgent works to sluice outfall 2004 • Business case approved for construction 2010 • Construction August 2011 to January 2012

4. Project background “Minsmere” is RSPB’s flagship nature reserve on the Suffolk coast.

5. Project background Minsmere / Dunwich Cliffs Flood risk area: Minsmere tidal sluice and outfall Sizewell Nuclear power station

6. Project background Environmental features: • Natura 2000 (SPA, SAC, Ramsar wetland); • SSSI; • AONB; • Ancient Monument; • Heritage Coast. y law, UK government is required to maintain these sites, where it is sustainable to do so • By law, UK government is required to maintain Natura sites in situ and in favourable condition, where it is sustainable to do so (providing compensatory measures for where this is not possible).

7. Project background Project was to: 1) Investigate the long term issues associated with flood risk (coastal and fluvial) on the Natura 2000 site: • Coastal modelling study; • Freshwater drainage study; • Review of existing defences and assets. Develop a preferred option for the short, medium and long term. Develop a business case for funding of works required in short term. Implement the works.

8. Existing defences Primary bank Secondary bank Minsmere Sluice and outfall enable freshwater drainage. North of Sluice: South of Sluice: Secondary dune Primary dune

9. Coastal change Coastal processes: • changes to offshore banks will reduce protection to shoreline; • Sea level rise will increase wave impact on defences. Fluvial drainage: • Sea level rise will restrict future freshwater drainage. Coastal squeeze: • Rising sea levels squeezeing the coastal habitat between defences and the sea.

10. Options “long list” to preferred option No Active Intervention – Walk away. Do Minimum – Maintain existing assets. Hold the line (groynes, reefs, breach recharge, cliff protection, improving sea defence banks) – maintain existing shoreline alignment. Managed realignment – new line of defence landward of existing defences.

11. Options “long list” to preferred option Sustainability appraisal:

12. Options “long list” to preferred option Greater clarity on Habitat Regulations: • Less value of maintaining designated features in situ - longer term viability of Natura 2000 network to be addressed through habitat creation. No longer considered sustainable to Hold the Line in the short term or to construct a completely new line of defence in the long term at Minsmere. • Natural England concluded that Holding the Line at the northern part of the site would be interpreted as “coastal squeeze”and that coastal features take priority (easier to provide compensation for freshwater habitats than coastal habitats). Realignment required at the northern end of the site with compensatory freshwater habitat.

13. …meanwhile….. • Surge events 2006 & 2007: Breaching of primary bank Footpath Scour

14. preferred option Adapt to coastal change: • Allow coastal change to take place (provide 28 Ha of freshwater replacement habitat) • Build up the North Wall to provide a new secondary line for ~50 years • Construct two coastal bunds to control and slow down the water that flows south from the breach site • Continue to maintain the sluice and outfall, and existing defences to the south of the Coney Hill Cross Bank

15. Environmental and social mitigation Protected species: • Water voles – vegetation strimmingprogramme, ecological survey, burrow destruction. • Bats – avoided night time / dusk working. • Nesting birds – timing of works, bird search before commencing, minimal use of artificial lighting. • Invertebrates and reptiles - vegetation strimmingprogramme, surveys, relocating. • Fish – re-location within the site via electro-fishing. • Vegetated shingle – access prohibited from beach, use of protective matting on coastal banks. • Species “management” cards developed for site staff

16. Environmental and social mitigation Invasive species : • pirri-pirri burr (invasive plant from New Zealand - located in site compound area. • Concern that it would be spread into the Nature 2000 site. • Use of protective mats and hardcore for site compound and access way to site. • Species management” card developed for site staff

17. Environmental and social mitigation Traffic management: • Importation of 6,000m3 of fill material along rural road network and through villages – high level of public concern. • Needed to avoid disruption to RSPB visitors. • High recreational useage of area by public (locals and visitors). • RSPB works overlapping. • Local events (at the RSPB reserve and wider community). • Included for passing bays and temporary traffic lights. • RSPB visitors approaching from several directions. • Coastal bunds constructed on coastal PRoW. • Traffic Management Plan developed

18. Environmental and social mitigation Amenity and tourism: • Minsmere is a major attraction locally – a clear message was required that reserve was open. • Regular newsletters and notice board updates to keep visitors and community up to date with the works. • Presentations to local parish council and interest groups. • Provision of information: • need for project • what we have done; • what we are doing next

19. Constructed scheme Before Before, post strimming Improved North Wall After

20. Constructed scheme Before Improved water control structure After

21. Constructed scheme Before After (bund 1) Coastal bunds After – Bund 2

22. Community involvement Yoxford Primary School:

23. Future management Next 5 years: • Refurbishment of the Minsmere Sluice. • Asbestos piling within the site. Short term (within 20 years): • Minsmere outfall. • Remedial works to the new water control structure. Medium term(20 to 50 years): • Possible realignment of secondary bank / North wall join. Long term (50 to 100 years): • Consider pumping at Minsmere Sluice if freshwater drainage is to be maintained. • Further realignment of sea defences or NAI.

24. questions