Presentation by Renske de Winter (University of Utrecht) at the XBeach X (10th Year Anniversary) Conference, during Delft Software Days - Edition 2017. Friday, 3 November 2017, Delft.

1. Sea level rise impacts
on the nearshore wave climate
and dune erosion
Renske de Winter, Gerben Ruessink
XBeachX
3 November 2017

2. Dune Erosion
sea level rise
waves
storm surge
dune erosion

3. XBeach validation
 Egmond aan Zee, the Netherlands
 Autumn 2011 hydrodynamic
measurements
 Storm January 2012
 Pre and post storm topography
measurements
 XBeach version V19-Easter
sea level rise
waves
storm surge
dune erosion

4. Observations
 Erosion is alongshore variable
 Erosion of embryo dunes
 Development of cliff
 Slumping of dune face
erosion (m)
 dune sea 
alongshore
sea level rise
waves
storm surge
dune erosion

5.  dune sea   dune sea 
Observations vs XBeach results
modelled
bed level change
observed
bed level change
r2= 0.55
Slope of regression line m
= 0.72
sea level rise
waves
storm surge
dune erosion

6. Sea level rise impact on dune erosion
 2 sites
 Offshore boundary conditions:
Egmond: storm surge = +5.5 m
Hs = 9.55 m, Tp = 16.1 s
Noordwijk: storm surge = +5.8 m
Hs = 8.55 m, Tp = 14.3 s
 Different sea level scenarios
( 0 – 2.5 m) added to offshore
storm surge level
 Sea level rise and change in wave
angle
sea level rise
waves
storm surge
dune erosion

7. Sea level rise impact on dune erosion
 Retreat distance is unrelated to sea level rise (Bruun-rule
not applicable).
sea level rise
waves
storm surge
dune erosion

8. Sea level rise impact on dune erosion
 Increase in erosion volumes are the
result of higher point of impact
(higher water levels) of the waves
on the dune front resulting from an
increased sea level.
sea level rise
waves
storm surge
dune erosion

9. Sea level rise impact on dune erosion
 Erosion volumes increase by
approx. 25% with 0.8m sea
level rise.
 50-80 m3/m /m sea level
rise
 Linear relation between the
increase in dune erosion
volumes and sea level rise
 This relation is site specific,
since hydroynamical
boundary conditions vary
per site.
sea level rise
waves
storm surge
dune erosion

10.  Deviation from shore normal
results in increased erosion
volume
 Increase same order of
magnitude as 40 cm sea
level rise
sea level rise
waves
storm surge
dune erosion
Sea level rise and wave angle
increase in erosion
wave angle
increase in eros
40 cm SLR

11. Sea level rise and wave angle
sea level rise
waves
storm surge
dune erosion
 Increased alongshore
currents

12.  Different sea level scenarios ( 0 – 3.5 m)
added to offshore storm surge level
 Profiles with different steepness (Egmond,
Petten(old), Ameland
 XBeach version Kingsday
 Wave height = 9.55 m, wave period = 16.1 s
Near shore wave climate and sea level rise
sea level rise
waves
storm surge
dune erosion

13. Near shore wave climate and sea level rise
 Short waves are higher
under an increase sea level
 Infragravity waves are
similar under all sea level-
scenarios
 Short waves are highest
for the steepest profile
(Petten)
 Infragravity wave heights
increase with lower bed
slope, but are independent
of increase in sea level.
sea level rise
waves
storm surge
dune erosion

14. Take home messages
 XBeach can model observed alongshore variability
 Not all erosion features are covered
 Retreat distance and sea level rise are uncorrelated.
Bruun-rule not applicable
 Level of attack (water level) is dominant for increase in
dune erosion, not the increase in short waves.
 Linear relation between sea level rise and dune erosion
volume (approx. 25% more dune erosion with 0.8 m
SLR).
 Wave angle increases dune erosion ~ as 40 cm SLR

15. Questions?
More info:
De Winter, Gongriep, Ruessink (2015): Observations and modeling of
alongshore variability in dune erosion at Egmond aan Zee, the
Netherlands,Coastal Engineering , vol 99, pp167-175
De Winter, Ruessink (2017): Sensitivity analysis of climate change impacts on
dune erosion: case study for the Dutch Holland coast, Climatic Change, vol
141, 685-701

16. Additional Slides

17. outlook
scenario
2050 2085
(2100)
2200
low 20 40 -
high 40 80 130
extreme 40 130 250
6 scenarios: 0, 20, 40, 80, 130, 250 (cm)
Sea level rise

18. de Winter, R., Reerink, T. J., Slangen, A. B. A., de Vries, H., Edwards, T., and Van de Wal, R. S.
W.: Impact of asymmetric uncertainties in ice sheet dynamics on regional sea level projections,
Nat. Hazards Earth Syst. Sci. Discuss., https://doi.org/10.5194/nhess-2017-86, 2017

19. de Winter, R., Reerink, T. J., Slangen, A. B. A., de Vries, H., Edwards, T., and Van de Wal, R. S.
W.: Impact of asymmetric uncertainties in ice sheet dynamics on regional sea level projections,
Nat. Hazards Earth Syst. Sci. Discuss., https://doi.org/10.5194/nhess-2017-86, 2017