Shoreline response to detached breakwaters: overview of design guidelines and application to field cases

Anglès: This study consists on the analysis of detached breakwaters and their influence on the shoreline response. Their importance to protect coastal strips against erosion and the difficulty to determine their complete behaviour and their relevant parameters, are the main aspects treated along the whole paper.First of all, a general overview of coastal dynamics is depicted. Second, a description of the actual coastal protection state is made, highlighting the reasons why coastal engineers have been focused on the problems and solutions related to coastline response for the last years.A comparison between the different measures that can be applied is realised in order to define their strong and weak points and to introduce offshore breakwaters as a valid and broadly applied option.The third item deals with detached breakwaters characteristics and influence on morphodynamic processes, and is the previous step to the exposure of the main topic of the thesis: the design guidelines.A subdivision between submerged and emerged breakwaters is made in order to achieve a better understanding of the process behind and around the structures, and highlight the relative difference of behaviour.General design guidelines, basically in form of geometric indicators, are defined and classified depending on their shoreline response description, for instance discerning between salient, tombolo and limited response. In order to determine the current validity of these indicators, and other parameters that seem to be relevant and were not taken into consideration, an overview of real reported cases is exposed. Comparisons between the results observed in the real cases with the guidelines and the numerical calculations realized on a first stage are described, stressing the complexity of the design of detached breakwaters.