Wave Overtopping in the Pre-Design of Coastal Works

Abstract

Wave overtopping situations, mainly caused by growing coastal erosion processes, directly affect the populations, causing coastal flooding, damages, and losses. Investments required for the construction and maintenance of coastal defence structures are thus expected to increase in the future over social, environmental and economically valuable coastal areas. The high costs incurred through coastal structures lifetime require improved knowledge on their performance, being important to deliver optimal solutions that consider impacts, costs and benefits. XD-Coast model was developed to facilitate pre-design processes of coastal structures and the COAST model was developed to perform subsequent cost-benefits analysis. However, the first version of XD-Coast does not allow forecasting wave overtopping phenomena. Thus, this work aims to improve the understanding of the overtopping impacts by including this valence in the XD-Coast and COAST numerical models, allowing to evaluate the relation between the structure design cost and the consequent costs due to overtopping and flooding hazard in the search for optimized solutions. Throughout this work it will be discussed the design of rocky revetments (slope and crown level) and their construction costs, with the potential benefits of reducing the overtopping and flooding consequences. A real case study on the Portuguese coast (Ovar) is also analysed. Conclusions demonstrate that the overtopping and flooding data recorded by the Portuguese Environment Agency (APA) and the ability to adequately reproduce it by formulations, can represent a step forward in the estimative of coastal overtopping and flooding impacts and to define a correlation between events and related costs.