The Masterplan Coastal Safety: a wave of opportunities

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1 The Masterplan Coastal Safety: a wave of opportunities In depth coastal research and state of the art maritime technology SPINCAM WEEK FLANDERS: OSTEND EVENT FEBRUARY 16-18th 2016 elias.vanquickelborne@mow.vlaanderen.be

2 Content Masterplan Coastal safety Underpinned by wide and detailed academic/scientific research & study Implementation through intensive monitoring strategies State of the art cases such as: - Nourishment program - Flood barrier - Stilling wave basin - Seadike reflecting wave concept - Nature expansion

3 Masterplan Coastal Safety More than 85% of the polders beneath +5m TAW (average storm)

4 Masterplan Coastal Safety Flood map of a 1000 year storm event

5 Masterplan Coastal Safety 1/3th of the Belgian coastline is not sufficiently protected against severe storm events. The Integrated Master Plan for Coastal Safety has been set up which forms the basis for the development of the seafront along the Belgian coast in the nearby and distant future (up till 2050) with safety against flooding as its main objective. estimated sea level rise in 2050: 30cm Proposed measures were approved on June 10th 2011 by the Flemish government Estimated cost: 300M

6 Scientific research & study First safety check (2007 till 2011) Norm: No fatalities due to a 1000 year storm Limited overtopping across the safety line: 1l/m/s No breaching of dunes and dikes No dune erosion that damages residential properties

7 Scientific research & study Outcome FSC

8 Scientific research & study Second safety check (ongoing) An update of the safety assessment methodology and hydraulic boundary conditions was needed New calculation methods for: - Beach and dune erosion: XBeach 2D - Determination of boundary condition at the toe of the dike: SWASH 2D - Calculation of wave overtopping: SWASH 1D + overtopping formulas

9 Intensive monitoring strategies Topography (LiDAR) & Bathymetry Hydrodynamic monitoring Ecological monitoring eg. pilot foreshore nourishment Mariakerke - Argus system: camera morphological changes - Intensified bathy, DTM, current and wave monitoring - Ecological monitoring (model input profile / grain size; output cf. species)

10 Nourishment program

11 Nourishment program

12 Nourishment program

13 Nourishment program Involved communities : De Panne Koksijde Westende Middelkerke Raversijde Mariakerke Oostende De Haan Blankenberge Knokke-Heist Up to now: 6,5 million m³ of wich over 4 million m³ sept sept Foreshore nourishments : decrease maintenance 2nd safety assessment in progress

14 Storm surge barrier Positioning: Nieuwpoort

15 Storm surge barrier Preconditions - Achieve a movable barrier - Passage width 38 m - Unlimited vertical clearance - Protection against a year storm (in 2100) Water level: + 7,64mTAW - Wave height Hs: 2,20m - Offer resistance to a + 8m storm (in 2100) Water level: + 8,64m TAW - Wave height Hs: 2,50m

16 Storm surge barrier Draft showing:

17 Storm surge barrier

18 Stilling wave basin

19 Seadike reflecting wave concept New sea wall Wenduine

20 Seadike reflecting wave concept Principle

21 Seadike reflecting wave concept Design: - Design storm: 1000 year annual recurrence interval storm: target value of discharge q = 1 l/s/m - During +8,0 m Superstorm: no breaching tolerable (q < 100 l/s/m) - Failure probability design of 1 % Physical scale models: optimal geometry of wave return walls and measure forces on wave return walls

22 Seadike reflecting wave concept Realisation seaside wave return wall with parapet

23 Seadike reflecting wave concept New sea wall Wenduine - detail

24 Zwin nature expansion Zwin Nature reserve

25 Zwin nature expansion Zwin Nature reserve

26 Zwin nature expansion Objective Combat silting up of the Zwin Add additional areas to the nature reserve (213ha) Limiting the risk of flooding for the hinterland (secondary objective) A cross-border expansion of 120 hectares 10ha on Dutch territory Total of 333ha Managed by MDK (project lead), ANB, VMM and the Province of Zeeland

27 Zwin nature expansion Actions Nature restoration in the existing is Zwin plain: typical estuary plants and animals by ensuring that the seawater is able to flow in and out of the Zwin more easily Gully excavated Controllable dam Separate islands for breeding birds

28 Zwin nature expansion Actions Dike: The new dike will be able to withstand a year storm. Length +/-3,9 km, Crest +/-7,5m NAP Cycling and hiking trail, viewing points & footbridge Improved water management in order to prevent problems of salinisation of the ground and surface water, flood damage and drought in the surrounding polder Salt/Fresh ditches & Fish-friendly pumping station

29 Zwin nature expansion Planning Extensive preliminary studies and procedures (i.e. expropriation of farmers/camping site and a zoning change FL + NL Appeal rejected 11/09/2015 (FL) & 23/09/2015 (NL) Urban planning permit (granted 09/06/2015) Construction file (opening tenders 18/09/2015) App. 13M Euro Start works (March 15th 2016) Excecution period: 3y Current dike can only be excavated when new dike is finished and verified

30 Het Zwin in verandering

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