Overtopping at port breakwaters and navigation risk using long-term multi-model numerical simulations

Abstract

This study assesses wave overtopping and ship maneuvering risks at Aveiro and Figueira da Foz ports, driven by climate change, namely sea level rise. The analysis is based on offshore wave hindcast data from the ECMWF database, covering a period from 1979 to present. Wave regimes are identified through statistical analysis of significant wave height, period, and direction for the years 2030, 2050, 2070 and 2100. These conditions, together with sea level rise projections, are downscaled using numerical wave propagation model SWAN, forcing NN_OVERTOPPING2 neural network to estimate mean overtopping discharge based on the local wave conditions, sea level and structural parameters. Ship manoeuvring safety will be analysed using the radiation/diffraction panel numerical model WAMIT, for linear analysis of surface waves interaction with floating structures. Maximum ship motions amplitudes along the navigation channel of each port will be computed, for the predicted local wave conditions and sea levels, allowing to establish new operating conditions. Following existing thresholds for admissible risk (overtopping and ship motions), risk levels changes from present to 2100 will be assessed. These results will enable the development of adaptive design and warning strategies. The proposed methodology supports effective risk assessment and can be applied to other coastal infrastructures and navigating channels.