Morphodynamic characterization of the Spanish beaches of the Gulf of Cadiz

During the1980s several attempts were made to classify beaches according to their morphodynamic behav- iour. Published papers proposed classifications based mainly on wave incident energy and beach character- istics, such as foreshore slopes and sediment settling velocities. In the 1990s more complex classifications appeared, where the effect of tides on wave action was included, highlighting their relevance to the determi- nation of the morphodynamic state of the beach. In this paper we present a beach monitoring programme, in which more than 30 beaches located along the Spanish shores of the Gulf of Cadiz and the Strait of Gibraltar were surveyed for four years (2000-2004). The long study period allowed the monitoring of beach morphologies related both to fair weather (summer) and storm (winter) conditions. The coastal setting in the study area provided the opportunity for covering a wide range of tidal conditions, from high mesotidal (MSTR ca. 4 m) to microtidal (MSTR around 1 m). Furthermore, the dimensions of the study area permitted the mon- itoring of beaches linked to different boundary conditions, thus including both attached and detached beach- es located at varying distances from main sediment sources, and influenced by different wave regimes. The analysis of the beach morphologies related to such contrasting conditions allowed the identification of the real significance of the tidal effect on beach profile morphology and hence on beach morphodynamics. Finally, we conclude that the effect of tides on wave action is the main factor determining beach morphody- namic behaviour. (Author)