Citation

Loureiro C, Ferreira, Cooper JAG. J. Coast. Res. 2009; (SI 56): 83-87.

Copyright

(Copyright © 2009, The Coastal Education and Research Foundation)

DOI

10.2307/25737542

PMID

unavailable

Abstract

Embayed beaches protected by rocky headlands evidence particular morphologic responses to episodic, seasonal and cyclic variations in external forcing depending on the degree of protection and shoreline orientation. This paper is concerned with the morphological behaviour of three embayed beaches (Cabanas Velhas, Boca do Rio and Salema) on the rocky south coast of Portugal that are subject to a moderate wave climate and have low sediment supply. The selected beaches show different geomorphological settings and have been regularly surveyed for measurement of morphological variability. Results show that when storms impact on an accreted profile with a well-developed berm all three beaches were highly responsive, with differences depending on coastal orientation and direction of incident waves. Severe erosion with depletion of sand and exposure of underlying layers of gravel and cobble or lag deposits of boulders occurred under single storms and storm groups. After severe erosion during storms, Cabanas Velhas and Boca do Rio did not show subsequent beach recovery. This may result from sand transport to outside the coastal cell and lack of an effective sediment source that enables recovery. The bi-directional storm wave climate, with storms occurring both from SE and SW, and the reduced headland confinement produced differential sediment displacement along opposing ends of Salema beach. Morphological adjustments, morphodynamic processes and the contrasting behaviour between these three embayed beaches appears to be strongly controlled by geomorphological inheritance.