165 Marine Technology and Engineering – Guedes Soares et al. (Eds) © 2011 Taylor & Francis Group, London, ISBN 978-0-415-69808-5 High resolution wave model simulations in the Portuguese nearshore Eugen Rusu, Marta Gonçalves & C. Guedes Soares Centre for Marine Technology and Engineering (CENTEC), Instituto Superior Técnico, Technical University of Lisbon, Lisbon, Portugal ABSTRACT: The performance of state of the art coastal wave models in the Portuguese nearshore are evaluated in the present work. This includes first the phase average coastal models, STWAVE and SWAN, and on the other hand the phase resolving models REFDIF and FUNWAVE. Some previous works that were carried out to implement and validate the above models are first outlined. This is followed by a brief description of the theoretical background of the wave models considered. The first field of experiments considered is Pinheiro da Cruz beach south of Lisbon characterized by smooth bathymetric contours. At this level the emphasis was put on performing comparisons in spatial frames concerning the field distributions of the main wave parameters provided by STWAVE and SWAN. The second target area considered is close to the Portuguese city Figueira da Foz almost equally distanced between Lisbon and Porto. In this location the bathymetry is rather irregular. Comparisons in the time domain are carried out in this area for a three-month period between December 1993 and February 1994. The third target area is a coastal sector located in the central part of the Portuguese continental nearshore, south of the city Figueira da Foz. Simulations with the models FUNWAVE and REFDIF1 were performed in parallel. The present work gives relevant information concerning the performances of different high resolution wave models as well as on the accuracy of their results in different coastal environments and for various forcing conditions. wave-current interactions and consistent results are presented in Rusu and Guedes Soares (2008b and 2011) and in Rusu et al (2011b) and assess- ment of the wave energy resources in the Portu- guese coastal environment as presented in Rusu and Guedes Soares (2008b and 2009). The same wave prediction system was implemented with very good results also in the Archipelago of Madeira as reported by Rusu et al (2008 a and b). As a continuation of the efforts carried out up to now to develop a reliable wave prediction system based on numerical models, the objective of the present work is to implement and compare high resolution computational tools that may constitute the final extension of this system and that are able to assess properly the local effects that usually occur in the coastal areas due to the bathymetric particularities or some other particular factors. Beside high resolution simulations with spectral phase averaged models STWAVE (Smith et al., 2001) and SWAN, two other wave models are considered in the present work. These are the phase resolving models REFDIF1 (Refraction-Diffraction Wave Model, Kirby and Dalrymple 1994) and FUNWAVE (Fully Nonlinear Boussinesq Wave Model, Kirby et al., 1998), which are more appro- priate for high resolution wave simulations in the coastal environment, where usually the wave 1 INTRODUCTION The work of establishing a comprehensive wave prediction system for Portugal has started with simple models and the moved into an implemen- tation of the WAM model (acronym from Wave Modelling, WAMDI Group, 1988) covering the whole North Atlantic. This was expanded into coastal areas by using the SWAN model (acronym for Simulating Waves Nearshore, Booij et al. 1999), as reviewed in Rusu et al (2011). This paper deals with the next level of detail of the system which includes the use of high resolution models in shallow waters and harbours. The implementation calibration and further development of this system is described first in Rusu et al (2005a and b). Extended hindcast stud- ies have been carried out, as reviewed in Guedes Soares (2008), Rusu et al (2008d), and also sensitiv- ity tests related to the influence of the resolution and accuracy of the wind field in the wave model performances as discussed in Ponce de León and Guedes Soares (2008) and Rusu et al (2008e and 2009) works that represent the prerequisite for the operational wave prediction system based on numerical models described in Guedes Soares et al (2011). Some other important issues studied using the above modelling system are related to the