1. Sigmaplan ‘Safety & Ecology’ Creating a sustainable estuary of the Schelde Patrik Peeters 18/05/10

2. 355 km 21.863 km 2 10,5 milion people Estuary of the Schelde

3. Storm surge in 1976

4. Schelde Durme Sigmaplan anno 1977 - Dike strengthening & heightening - Flood Control Area (FCA)

5. ScheldeFCA 1 2 3 4 Ring dikeLowered levee 1 2 3 4 Working principle of a FCA

6. 90 m 54 m 120 m 123 m Sigmaplan anno 1977 - Flood barrier

7. Sigmaplan anno 2005 No longer 1 flood protection level – Flood risk assessment Taking into account possible breach formation Combination of dike strengthening and FCA Based on a SCBA

8. Water management today: limit the damage Water level 1. Probability 2. Flood modeling 3. Damage calculations 4. Risk = Σ Probability x Damage Flemish Risk Methodology

9. Sigmaplan anno 2005 Adressing ecological needs System approach Habitat approach Species approach More space for the estuary Non-tidal wetlands Combining FCA with agriculture non-tidal wetland a Controlled Reduced Tide (CRT)

10. Pilot Project LIPPENBROEK Flood Control Area (FCA) with a Controlled Reduced Tide (CRT) Ring dike Overflow dike Inlet structure (high sill) Outlet culvert (low sill, flapped) Semi-diurnal water exchange Creation of intertidal habitat with inundation characteristics similar to natural conditions, ie. profound springtide/neap tide cycle

11. Outlet (low sill) and inlet (high sill)

12. Springtide/neap tide cylce Reduced tide Stagnante phase

13. Pilot Project LIPPENBROEK INLET (CRT side) OUTLET (river side) OUTLET (CRT side) Overflow dike

14. Freshwater Intertidal Habitat CREEK RESERVOIR SHALLOW POOL ready for colonisation, nutrient cycling, …

15. Discharge measurements At the inlet Rectangular section Sharp-crested weir

16. At the inlet By ADCP Head-discharge relations Discharge measurements

17. At the outlet Rectangular section Broad-crested weir Trash rack By ADCP Validation of continuously measured flow velocities and water levels Discharge measurements

18. At the outlet Discharge measurements

19. Sediment sampling Each in- and outflow At in- and outlet Tidal sampling SSC in laboratory (mg/l) At distinguished moments: detailed sampling Turbidity measurements (NTU)

20. Sediment sampling Relations between Q (m³/s), SSC (mg/l) et turbidity (NTU) Eg. at the inlet:

21. Water and sediment balance

22. Sediment balance

23. Sedimentation pattern Measurement of elevation changes by SET SET: Surface Elevation Tables

24. Yearly elevation change Elevation change as a function of tidal inundation frequency (average: 2-3 mm/year)

25. Improving connectivity Between estuary and FCA, non-tidal wetlands, tributaries, … Enhancing (fish) migration Fish passages Fish-friendlier tide gate designs Culvert adjustments

26. Fish immigration Fish emigration INLET OUTLET Improving connectivity

27. Tide gate of outlet Lippenbroek 1.80m x 1.80m Double hinged from above Small opening at low flows Turbulent at high flows, but with sufficient opening

28. Side-hinged “Pet Door” Mono-hinged “Pet Door”

29. Thank you for your attention Suggestions, questions, … patrik.peeters@mow.vlaanderen.be