1. 5-7-2014 Challenge the future Delft University of Technology Dune erosion during storm surges Jaap van Thiel de Vries Picture: Beach and dunes near Westenshouwen

2. 2 Titel van de presentatie Dune erosion Maximum storm surge level Pre-surge dune foot Post-surge dune foot Pre-surge beach width Post-surge beach width Mean sea level Dune erosion during storm surges

3. 3 Titel van de presentatie Societal importance Dutch safety policy against flooding: •“Dijkringen” •Weakest link in a “dijkring” determines safety against flooding •Strength primary water defenses against normative conditions is assessed every five years. •Strength dunes is assessed with empirical guideline elaborated from large scale dune erosion experiments Dune erosion during storm surges

4. 4 Titel van de presentatie Societal importance Hondsbosche en Pettemer sea defense Scheveningen Head of Noord-Holland Head of Walcheren Dune erosion during storm surges

5. 5 Titel van de presentatie Thesis outline Thesis outline: •Large scale dune erosion tests in the Deltaflume •Interaction of dune and swash •New approach in modeling near dune hydrodynamics •New approach in modeling near dune sediment concentrations •Coupling of new physical insights in a 2DH morphodynamic model Objective: Improve our physical understanding of dune erosion in order to develop a more generic dune erosion model. Dune erosion during storm surges

6. 6 Titel van de presentatie Deltaflume experiment Dimensions: 220m x 5m x 7m Depth scale = 6 Irregular waves; Hm0=1.5m Dune erosion during storm surges

7. 7 Titel van de presentatie Deltaflume measurements In-situ Stereo Video Dune erosion during storm surges MOBILE FRAME STEREO VIDEO FLUME WALL

8. 8 Titel van de presentatie Deltaflume results Pressure sensors on flume wall: Suction tubes on shallow water frame: Dune erosion during storm surges duin golfschot Korte (wind) golven Lange golven

9. 9 Titel van de presentatie Deltaflume results Incoming bore Shore line Reflected wave Dune crest Dune erosion during storm surges

10. 10 Titel van de presentatie Dune erosion during storm surges Modeling near dune hydrodynamics The generation of long waves due to variations in the wind generated short waves

11. 11 Titel van de presentatie Dune erosion during storm surges Modeling near dune hydrodynamics

12. 12 Titel van de presentatie Dune erosion during storm surges Modeling near dune hydrodynamics

13. 13 Titel van de presentatie Dune erosion during storm surges Near dune sediment concentrations T bore Hypthesis: High near dune sediment concentrations are caused by wave breaking induced turbulence that is injected in the water column over a short time interval and reaches the bed as a pulse.

14. 14 Titel van de presentatie Dune erosion during storm surges Near dune sediment concentrations

15. 15 Titel van de presentatie Dune erosion during storm surges XBeach New physical insights are coupled in the morphodynamic model XBeach that: •Solves both short waves (energy balance) and long waves (Nonlinear Shallow Water Equations); •Includes a formulation that also relates the sediment concentration to the wave breaking induced turbulence pulses that potentially reach the bed; •Includes the longshore direction.

16. 16 Titel van de presentatie Dune erosion during storm surges LEF Restaurant en Bar Doelenplein 2, Delft Google maps