This document discusses modeling the response of a deltaic, curvilinear coastline to extreme weather events. The study area contains hotspots sensitive to storm impacts. Both the hazard probability and consequences of storms are expected to increase. Coastal managers need decision support and early warning systems to estimate hazard extent and magnitude. The model successfully reproduced a 2008 storm event and showed the coast is similarly sensitive to changes in wave direction and projected sea level rise. Future work should include additional validation cases and accounting for wave asymmetry in steep environments.

1. UNDERSTANDING THE RESPONSE TO EXTREME
EVENTS OF A DELTAIC CURVILINEAR SENSITIVE
COAST
PAIRISC-CLIMA
CGL2014-55387-R
Universitat Politècnica de Catalunya
Marc Sanuy (marc.sanuy@upc.edu)
José A. Jiménez

2. HOTSPOT  Spot in the coast sensitive to the impact of
extreme events (storms)
RISK  (Hazard probability) x (Consequences)
Both components are likely to increase
COASTAL MANAGER NEEDS:
• Decision Support Systems
• Early Warning Systems
Need to estimate extension and
magnitude of hazards of interest

4. HOTSPOT  Spot in the coast sensitive to the impact of
extreme events (storms)
RISK  (Hazard probability) x (Consequences)
Both components are likely to increase
COASTAL MANAGER NEEDS:
• Decision Support Systems
• Early Warning Systems
Need to estimate extension and
magnitude of hazards of interest
Model Train Set-up
Calibration / Validation
Sensitivity to Dir Change
Sensitivity to SLR
Performance of measures

6. Dic. 2008 storm
0
2
4
6
8
10
12
14
16
0 20 40 60 80 100
Tp(s)
hr from 26th at 00:00
Bouy observations Simulation

7. BSS = 0,51
BSS = 0,73
Overall
BSS = 0,65
Dic. 2008 storm

8. P1 P2
P3 P4
Dic. 2008 storm

9. 2008 Event 2008 + 20 º2008 – 20º 2008 + 40 º

10. 2008 Event 2008 + 20 º2008 – 20º 2008 + 40 º

11. 2008 Event
RCP 8,5
SLR
2100
(0,73 cm)
No SLR
+20º
towards
South

13. 2008Event
Current
N + D

14. 2008 Event 2008 + 20 º2008 – 20º

15. 2008 Event 2008 + 20 º2008 – 20º

16. CONCLUSIONS (from local results)
 Model train is successful in both propagation and hazard estimation. Limitation!: Validation
was only performed using one reference historical event (2008)
 TD has complex layout: very steep environment, coarse sediment, hard structures.
Nevertheless: good reproduction of the morphodynamic response with XB surf-beat mode
 Better performance north of the river (more orthogonal to storm incidence) than in the
south (more oblique). Bathymetry in the south is also more complex  higher
hydrodynamic complexity
 The study site is “almost equally” sensitive to a switch in incoming wave direction (20-40º)
towards south than to SLR RCP 8.5 2100 (inundation hazard only).
 Nature based bar reconstruction needs to be furtherly studied. The tested measure does
not reach the efficiency of the more classical Nourishment + Dune. Long term
behaviour????

17. LESSONS LEARNED (and future work)
 Surfbeat XB has good skill on reproducing morphodynamic patterns (along- and crosshore).
Non-H XB showed worse skill to capture those.
 Deviations on wave propagation before XB boundary lead to more significant deviations on XB
estimations in subzones with highest obliquity.
 Steep environment: inf. waves have less contribution to run-up:
 DELTA  0,5 ; GAMMA  0,7 increased wave attack due to steep environment
 Finer crosshore resolution of the grid in the intermediate depths
 No available hydrodynamic data to validate wave breaking
 Steep environment: wave assymetry/skeewness  non-linearity on sediment transport :
 Increased FACUA  0,6 (Elsayed and Oumeracy 2017 used FACUA = 0.5)
 Too much sediment suspension leading to overestimation of erosion/deposition processes
 McCall 2010 ; Elsayed and Oumeracy 2017 : sediment is more stable in steep env.
 SEDCAL set to 0,1 to get the appropriate morphodynamic results.
 Is the model set-up overfitted?? Need data on more storms at the same CSS to further study this
(more validation cases).

18. THANK YOU
Universitat Politècnica de Catalunya
Marc Sanuy (marc.sanuy@upc.edu)
José A. Jiménez
PAIRISC-CLIMA
CGL2014-55387-R