Articles | Volume 16, issue 12
Research article
01 Dec 2016
Research article |  | 01 Dec 2016

Contribution of storms to shoreline changes in mesotidal dissipative beaches: case study in the Gulf of Cádiz (SW Spain)

María Puig, Laura Del Río, Theocharis A. Plomaritis, and Javier Benavente

Abstract. In this study an analysis of storminess and rates of shoreline change is performed and discussed jointly in four geomorphological units of the Gulf of Cádiz (SW Spain) for the period of 1956–2010. For this purpose, storm events are identified based on the following characteristics: wave height above 2.5 m, a minimum duration of 12 h and events with calm periods of less than 24 h were considered as a single event. Subsequently, energy parameters are determined in order to characterize storm-induced impacts. Conversely, geographic information system (GIS) tools are used to measure shoreline changes in aerial photographs and orthophotographs of each site, selecting the high water line as shoreline proxy. Each geomorphological unit is divided into different behavioural patterns according to recorded coastal changes, so that each one shows a particular behaviour.

In general the variability of shoreline changes that is explained by storms and the relation between storm parameters and coastal changes present better results in exposed areas (Cádiz and Vistahermosa) than in sheltered areas (Valdelagrana spit barrier) because the former are more sensitive to storm impacts. On the contrary, in areas where there is no relation between coastal changes and storm parameters (Valdelagrana and Sancti Petri sand spit), it is suggested that anthropogenic factors are the main forcing agents determining shoreline behaviour. However, in these areas the storminess also modulates coastline recession by increasing erosion when the number of storms is high.

Short summary
This work evaluates shoreline response to storm impacts at four beaches in SW Spain by comparing medium- and short-term rates of shoreline change and storm parameters. Results show that shoreline behaviour is mainly determined by both anthropogenic and geological factors. Moreover, a correlation is found between storm parameters and shoreline changes in exposed areas with a low degree of human intervention. This work provides a useful contribution to the prediction of coastal variations.
Final-revised paper