Assessment of TELEMAC system performances, a hydrodynamic case study of Anglet, France

Abstract

The wave propagation and flow modules of the TELEMAC system have been applied to the Adour River mouth and the adjacent beaches of Anglet (France). The wave propagation has been simulated using the phase-averaged model TOMAWAC. In addition, the phase-resolving REFDIF S model has been also used, as the diffraction of wind waves, which is not taken into account in TOMAWAC, can occur in the vicinity of the River mouth. Next, the hydrodynamics has been simulated using the two-dimensional depth-averaged flow TELEMAC 2D model. The numerical results are compared with field measurements collected in March 2003. Model performance statistics are calculated in order to assess the accuracy of the predictions at six locations. Regarding the computation of the wave propagation, a root mean square error (RMSE) is evaluated for the significant wave height, the mean period and the peak direction of propagation. For the flow computation, a mean absolute error (MAE) is used as it is applicable to vector quantities. A classification is also adopted that categorises the quality of the results. Regarding the significant wave height, the average relative RMSE is of 18.2% for the TOMAWAC computations whereas the error is of 30.8% for the REFDIF S simulations. Concerning the peak wave direction, the RMSE is about 10°. Both models predict the wave direction normal to the shore whereas the experimental parameters are more variable. However, the areas, where energy concentrates, are well reproduced. The classification of errors shows that TELEMAC 2D flow predictions are in a range from excellent to reasonable.