Modeling Shoreline Changes in Northwest Portugal Using a Process-Based Numerical Model: COAST2D

Abstract

The coastal stretch between Vagueira and Praia de Mira, northern Portugal, is subject to high-energy wave conditions. At the same time, the shoreline is a main contributor to the local economy, extensively due to tourism. Despite the shoreline being currently protected by groynes, a better understanding of the hydrodynamics and the morphodynamics in the area is crucial for coastal managers and planners. In this work, it is intended to use a process-based model, COAST2D, to predict the beach morphological changes of the said sandy beach as the study site. The model is applied to simulate the morphological changes over a 4-month period between October 2013 and February 2014 to the study site, during which a series of high-intensity storm events occurred along the west coasts of Europe. Model results are compared with the measurements from topobathymetric fieldwork campaigns. The model results show the effect of the groynes on the nearshore coastal processes under the combined wave and tide conditions. The predicted morphological changes agree well with the field measurements. The model results also show the shoreline sensibility at the study site to high-energy waves during storms, where the shoreline changed its slope to adapt to the more energetic conditions. The results clearly demonstrate the capability of COAST2D in modeling the complex hydrodynamics and morphodynamics at the study site in a seasonal scale.