Applicability of Wave Models in Shallow Coastal Waters(3)

A comparison of the calculated significant wave heights at the locations of buoy no. 1 and 2 andof the measured wave heights is given for the complete test collective in figure 4.

H u o y 1 [m]s , b

Hs , b u o y 2 [m]

num.

num.

exp.

H [m]s, buoy 1

exp.

H [m]s, buoy 2

Figure 4

Comparison of the significant wave height obtained from field measurements and

simulations with SWAN at the location of buoy no. 1 (left) and buoy no. 2 (right).

Even though the wave parameter measured at buoy no. 1 were used to prescribe the incomingwave field the significant wave height at the location of buoy no.1 is underestimated by thenumerical simulations using the standard model parameters, especially in case of significant waveheights Hexp.m. This may be contributed to a too low energy input by wind generation. Thes,buoy1>17average quotient of simulated and measured wave heights at buoy no. 1 is approximatelyα=91%. At the location of buoy no. 2 the same underestimation of wave heights can be found,the average quotient of simulated to measured wave heights is α=89%. But still a clearcorrelation of measurements and numerical simulations is evident. The correlation coefficient isapproximately r2=0.97. One reason for the scatter of modelled wave heights around measuredheights may be the interaction of the tidal currents with the wave field.

5. CONCLUSION

The wave models HISWA, SWAN and MIKE 21 EMS are applicable very well for forecasts of thetransmission coefficient at forelands and summer dikes. Best results in comparison withexperimental wave tank data was achieved with model parameters of friction and wave breakingonly slightly changed from the recommend values in the manuals.

The simulations of wave propagation in coastal shallow waters using SWAN revealed differencesin wave height from measured data up to 30 %. These may be contributed in part to the influenceof tidal currents on waves.ACKNOWLEDGEMENT

We thank our colleague Dr.-Ing. K.-F. Daemrich for his support during the experiments in thewave tank and his contributions to the data analysis and interpretation. REFERENCES

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