1. TNC meeting, May 28-31 2013, New Orleans, Louisiana Science & Tools: Effectiveness and Multiple Benefits of Natural Defenses/Infrastructure: How Does It Stack Up Against and Integrate with Built Infrastructure Dutch experiences Jaap Kwadijk Director of Science Deltares

2. Flood risk in The Netherlands 20th November 2012 Economically Efficient Flood Protection Standards 2/3 flood-prone, 9 million inhabitants, 65% GNP, 1800 billion € invested value

3. All generations have their own flood) 16751682 19161953

4. 4 Before 1995, Dutch reaction built infrastructure

5. 1995, a transistion, Room for the River ?

6. New standards  fail proof, multifunctional Deltadikes? New solutions to prevent floods Building with nature, sand engine, oyster reefs (eco engineering)

7. Focus on ecosystem-based eco-engineering Why should we make use of natural processes and ecosystem services in flood risk mitigation (in combination with hard engineering)? 1.Cost reduction 2.Reduces risk on failure 3.Adaptable

8. Marshland kwelders Foto paesens-moddergat Effective low cost low tech saltmarsh produces safety & large natural value Dutch historical large scale land reclamation = building with nature

9. soft eco-engineering dike concept with reef, marsh, dune combinations Not safe enough? safe Long term safety: Marshes grow with SLR Very safe reefs Marshes/ mangroves Sandy foreshore needs nourishment

10. Wavereducing forest-dike combi ‘fort Steurgat’ Deltares/RWS concept achieves required 1/2000 safety standards and now under construction Wave reducing willow-tree plantations Low cost low tech Clay dike will be lower than traditional design 100m wide

11. Vegetatie als golfremmer Saltmarsh grows with sea level and maintains stability and safety Flexible, low tech, low maintenance cost, longshore connectivity Hinterland Old dike Muddy coastline Wave reducing saltmarsh Super storm stable vegetated dune Muddy coast Soft Safe Dike: saltmarsh/dune/dike hybrid Existing dike 500m

12. Artificial oyster reefs Small scale pilot 2009 12 x 4 m Large scale pilot 2010 Each reef: 400 m 3, ± 230 tons of oyster shells 200 x 10 m Oyster reefs as a short / midterm solution for erosion problem in the Oosterschelde

13. Sand Engine to cope with SLR: Experiment Observed evolution (1st year)

14. Measured bathymetry after 1 year Initial After 3 year After 5 years After 10 years After 20 years D3D Model prediction 20 years (pre-project) Figures courtesy of Rijkswaterstaat / Shore Monitoring & Research Measured / predicted evolution (Delft3D)

15. Building with Nature projects overview 2009 2008 2007 USA!? SNG The Netherlands are leading in eco-engineering applied for safety against flooding 2010

16. Problem: Safest delta in the world By law (water act): Extremely high safety standards Maintenance of the structures Detailed standards on flood prevention structures

17. Pro’s and con’s Some are extremely efficient examples (sand nourishment) Some are probably effective Potentially more adaptable Potentially multi purpose Not clear how effective the measures are No handbooks on design and evaluation Not considered as “engineering” Not “one size fits many” Legal risk to implement them