The document summarizes a study that assessed the performance of the SWAN wave model under extreme conditions in the Wadden Sea. Stationary SWAN computations were performed for 8 time periods during a storm in December 2013 and results were validated against measurements from multiple wave buoys. Different SWAN settings were tested, including default settings as well as configurations with and without currents. The reference SWAN settings that include currents performed best. While currents had a limited direct effect on wave growth, omitting them led to degraded results. The updated default SWAN settings performed better than previous defaults. In conclusion, SWAN can accurately model nearshore waves during storms in the Wadden Sea when appropriate settings are used.

1. IAHR World Congress 2015
Den Haag, 30th June 2015
Validation of SWAN under extreme
conditions in the Wadden Sea
Amaury Camarena
Caroline Gautier
Joana van Nieuwkoop

2. Introduction
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3. Introduction
• Hydraulic Boundary
Conditions partly derived by
the SWAN model.
• Assess the performance of
SWAN when simulating
extreme conditions.
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4. Study area
Ameland
Eastern Wadden Sea
• Stationary SWAN computations: Storm 5th and 6th December 2013
• Several wave measuring devices available for comparison and validation
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5. Available data and case selection
Eight different times are selected to undertake stationary SWAN
computations (pre, during, post storm).
• Tidal phase
• No large offshore temporal variation
• Availability of data in buoys
(buoys are shown by the different colors)
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6. SWAN model setup
-Wind input: HARMONIE
-Wave input: Wave buoys
-Water level and current input: Delft3D-Flow coupled with waves
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7. SWAN settings
A-series: Reference settings, including currents (based on the
research carried out for the so-called ‘Wettelijk
toetsinstrumentarium’ (WTI) project).
B-series: Reference settings, deactivating currents.
C-series: Komen wind growth and whitecapping with delta=1. These
are the SWAN default settings in version 40.91.A.
D-series: Komen wind growth and whitecapping with delta=0.
Represent the previous default SWAN settings before version
40.91.A.
E-series: Reference settings, without enhanced whitecapping due to
currents (Cds3=0).
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8. Results - Ameland
• * represent the measured value at the time of the event
• + shows 1 hour after
• □ 1 hour before
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9. Results - Eastern Wadden Sea
• * represent the measured value at the time of the event
• + shows 1 hour after
• □ 1 hour before
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10. Statistical performance of SWAN - Ameland
ID SETTINGS BIAS
STANDARD
DEVIATION
ROOT
MEAN
SQUARE
RELATIVE
BIAS
RELATIVE
STANDARD
DEVIATION
NUMBER
OF
SAMPLES
HM0 A Westh Cds3=0.8 -0.02 m 0.26 m 0.26 m -1.9 % 20.6 % 72
HM0 B Westh (no currents) -0.01 m 0.24 m 0.24 m -0.9 % 18.9 % 72
HM0 C Komen, δ=1 0.13 m 0.37 m 0.39 m 10.0 % 29.0 % 72
HM0 D Komen, δ=0 0.10 m 0.40 m 0.41 m 8.1 % 31.5 % 72
HM0 E Westh Cds3=0.0 0.04 m 0.29 m 0.29 m 3.5 % 23.1 % 72
TM-1,0 A Westh Cds3=0.8 -0.25 s 0.50 s 0.56 s -4.8 % 9.5 % 72
TM-1,0 B Westh (no currents) -0.41 s 0.65 s 0.77 s -7.9 % 12.4 % 72
TM-1,0 C Komen, δ=1 -0.43 s 0.71 s 0.83 s -8.3 % 13.6 % 72
TM-1,0 D Komen, δ=0 -0.86 s 0.77 s 1.15 s -16.5 % 14.7 % 72
TM-1,0 E Westh Cds3=0.0 -0.31 s 0.55 s 0.63 s -5.9 % 10.6 % 72
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11. Statistical performance of SWAN - Eastern Wadden Sea
ID SETTINGS BIAS
STANDARD
DEVIATION
ROOT
MEAN
SQUARE
RELATIVE
BIAS
RELATIVE
STANDARD
DEVIATION
NUMBER
OF
SAMPLES
HM0 A Westh Cds3=0.8 0.20 m 0.28 m 0.34 m 10.4 % 14.6 % 48
HM0 B Westh (no currents) 0.23 m 0.28 m 0.36 m 11.8 % 14.7 % 48
HM0 C Komen, δ=1 0.35 m 0.40 m 0.53 m 18.6 % 21.1 % 48
HM0 D Komen, δ=0 0.55 m 0.55 m 0.77 m 29.0 % 28.7 % 48
HM0 E Westh Cds3=0.0 0.27 m 0.30 m 0.40 m 14.3 % 15.9 % 48
TM-1,0 A Westh Cds3=0.8 -0.3 s 0.6 s 0.7 s -5.2 % 9.7 % 48
TM-1,0 B Westh (no currents) -0.5 s 0.8 s 0.9 s -7.4 % 11.6 % 48
TM-1,0 C Komen, δ=1 -0.9 s 0.8 s 1.2 s -14.1 % 11.9 % 48
TM-1,0 D Komen, δ=0 -1.5 s 1.1 s 1.9 s -22.7 % 16.6 % 48
TM-1,0 E Westh Cds3=0.0 -0.6 s 0.6 s 0.8 s -8.3 % 9.5 % 48
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12. Conclusions
• The reference settings (Series-A) perform significantly better than the
standard SWAN settings especially in areas with mixed swell and wind-
sea conditions.
• The present default SWAN settings (version 40.91.A), which includes
Komen wind growth and whitecapping with delta=1 (C-series), give a
better approximation of wave conditions than previous settings (Komen
with delta=0, D-series) during extreme events on areas dominated by wind
sea and swell like the Wadden Sea.
• Whitecapping formulation and associated calibration parameters strongly
influence the results of the SWAN model.
• Although the effect of currents on wave growth is limited, it cannot be
omitted.
• Overall it is concluded that SWAN is a high quality tool to compute
nearshore waves during storms in the Wadden Sea when the adequate
combination of settings is used.
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13. Questions?
30 June 2015
Amaury Camarena Calderon
Consultant / Researcher
T +31(0)88335 8029
E amaury.camarenacalderon@deltares.nl
www.deltares.com
P.O.Box 177
2600 MH Delft
The Netherlands

14. Results - SWAN (series A) vs measurements
AZB11 AZB 31 AZB 41 AZB 51 AZB 61
AZB 12
(G1A)
AZB 12
(G2A)
AZB 22 AZB 32 AZB 42 AZB 52 AZB 62
T1A 0.13 -0.07 0.06 0.06 0.27 0.06 -0.01 -0.17 0.07 0.18 -0.26 -0.20
T2A 0.14 -0.07 -0.05 -0.08 0.09 0.10 0.00 -0.22 0.19 0.14 0.11 0.03
T3A 0.04 0.10 -0.01 -0.01 0.33 0.16 0.00 -0.25 0.14 0.06 0.03 0.06
T4A 0.16 -0.09 -0.02 -0.15 0.06 0.11 0.00 -0.31 -0.14 0.28 -0.17 -0.21
T5A -0.01 -0.02 0.33 0.27 0.39 -0.04 0.10 0.04 0.06 0.04 0.17 0.47
T6A -0.01 -0.16 -0.17 -0.15 0.08 -0.06 0.00 -0.37 -0.21 0.16 0.03 -0.09
T7A -0.05 0.20 0.10 0.06 0.35 0.02 0.00 -0.27 0.07 0.34 0.07 0.11
T8A 0.05 0.18 0.50 0.50 0.91 0.02 0.00 -0.38 -0.01 0.29 0.42 0.04
BRKN
(G1E)
BRKN
(G2E)
WEW WEO RZGN OWEN OWEZ UHW2 LAUOT BOSZ PBW
T1E 0.00 -0.01 -0.04 0.14 0.36 0.69 0.36 0.58 0.30 0.20 0.25
T2E 0.02 0.00 -0.05 0.01 0.39 0.51 0.73 0.14 0.27 0.10 0.15
T3E -0.02 0.00 0.13 -0.05 0.39 0.21 0.23 0.27 0.15 0.00 0.08
T4E 0.02 0.00 -0.05 0.12 0.15 0.12 0.59 -0.22 0.11 -0.13 -0.12
T5E 0.01 0.00 -0.24 0.06 0.18 0.86 0.89 -0.07 0.02 0.03 0.23
T6E -0.02 0.00 -0.15 -0.04 0.02 -0.04 0.36 0.03 0.16 0.04 0.21
T7E -0.01 0.00 0.07 0.03 0.09 0.44 0.56 -0.15 0.16 -0.11 -0.06
T8E 0.01 0.00 -0.07 0.14 0.37 0.71 1.04 -0.19 0.25 0.09 0.11
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