Cross-shore Evolution of Buarcos Beach, Portugal

Abstract

The seasonal morphological and sedimentary changes of Buarcos beach, in the central Atlantic west coast of Portugal, are discussed based on the analysis of one year of monitoring wave, topographic and sedimentary data and the application of numerical modeling. The beach is part of an important seaside resort area and is characterized by a narrow sandy fringe limited landward by urban infrastructures and at the lower foreshore by an active erosive platform of rock outcrops. During the study period the beach suffered important sediment loss (approximately 300x103 m3) without seasonal recovery of the reflective profile. The results show longitudinal variability of the cross-shore morphological response of the beach to the hydrodynamic conditions. This is related to an evident alongshore variability of the wave action along the beach, mainly for NW incoming waves, being the north sector the one more affected. The morphological response of the beach to storm events was dependent on the gradient of the cross-shore profile. The sedimentary content of the beach remained almost constant in time indicating uniformity in the source of sediment. Due to the beach low volumetric content, perturbations of the typical seasonal morphological evolution can have an important impact on the beach stability in a longer time scale.