Water Waves

In the present study, a recently developed novel approach (Bender et al. in J Hydrol 514:123-130, 2014) has been further extended to investigate the changes in the joint probabilities of extreme offshore and nearshore marine variables with time and to assess design the total water level (TWL) at the shoreline under the effects of climate change. The nonstationary generalised extreme value (GEV) distribution has been utilised to model the marginal distribution functions of marine variables (wave characteristics and sea levels), within a 40-year moving window. All parameters of the GEV were tested for statistically significant linear and polynomial trends over time, and best-fitted trends have been detected. Different copula functions were fitted at the 40-year moving windows, to model the dependence structure of extreme offshore significant wave heights and peak spectral periods, and of wave-induced sea levels on the shoreline and nearshore sea levels due to storm surges. The most appropriate bivariate models were then selected. Statistically significant polynomial trends were detected in the dependence parameters of the selected cop-ulas, and time-dependent most likely bivariate events were extracted to be used in the estimation of the TWL at the shoreline. The methods of the present work were implemented in three selected Greek coastal areas in the Aegean Sea. The analysis revealed different variations in the most likely estimates of the offshore wave characteristics and nearshore storm surges in the three study areas, as well as in the time-dependent estimates of TWL at the shoreline. The approach combines nonstationarity and bivariate analysis, blends coastal and offshore marine features and finally provides non-trivial alterations in the response of coastal sea level dynamics to climate change signals, compared to former work on the subject. The methodology produces reasonable estimates of design quantities for coastal structures and boundary conditions for the assessment of flood hazard and risk in coastal areas.

In this paper, we present recent evolvements of three robust numerical models for the simulation of the evolution of wave fields and hydrodynamic circulation in gulfs and coastal areas with large harbours and significant urban port facilities. The models are integrated into a single software suite for the development of a decision support tool to provide reliable forecasts of sea states prevailing at selected important ports worldwide. The application of the integrated modelling platform is designed to support approaching procedures of vessels to ports and it is based on co-operating, high-resolution, hydrodynamic (ocean and wave) models that derive input data and boundary conditions from global scale or regional, open sea and weather forecasts. The implementation of short-term forecasts for sea conditions includes the development, validation, coupling, and operational application of: i) the High Resolution Storm Surge (HiReSS) model for sea level variations; ii) the 3rd generation spectral wave model called TELEMAC-based Operational Model Addressing Wave Action Computation (TOMAWAC) for irregular wave propagation in offshore and coastal areas; and iii) a high resolution phase-resolving wave model (WAVE-L) for port basins, based on the hyperbolic mild-slope equations. This innovative product, designed for port-related endusers, will improve the navigation safety at ports, optimize the berth occupancy, support the port pilotage operations, mooring and towage procedures, and may facilitate the port layout upgrade or design. Hereby, pilot forecast implementations are presented concerning the Mediterranean Sea and eight selected harbours in it.