Offshore-to-Nearshore Transformation of Wave Conditions and Directional Extremes with Application to Port Resonances in the Bay of Sitia-Crete

Flora Karathanasi,Angeliki Karperaki,Theodoros Gerostathis,Kostas Belibassakis

doi:10.3390/atmos11030280

Abstract

For coastal engineering studies and the efficient design of ports and harbors, reliable information concerning wave conditions in nearshore and coastal sites is needed. In the absence of long-term wave data at the site of interest, this becomes possible by using offshore data, which are usually available in the nearby geographical area, in addition to bathymetric and coastline information concerning the nearshore area and the local site. The latter are used in conjunction with a suitable wave model, which calculates the offshore-to-nearshore transformation of wave conditions and incorporates the relevant shallow-water phenomena. In the present work, the above methodology is applied to calculate the nearshore wave conditions in the Bay of Sitia, Crete, by applying the Simulating WAves Nearshore (SWAN) model. The interesting feature of the Bay of Sitia is its vulnerability due to strong erosion, which downgrades the touristic value of the beach. Furthermore, nearshore wave data offer valuable information concerning further coastal and port engineering studies. In this context, results from directional extreme value analysis of the nearshore wave conditions in the Sitia Bay are derived and used to investigate resonances in the enclosed marina of the Sitia port, by taking into account the depth variations inside the basin. To this end, a novel method was developed based on the modified mild-slope equation, in conjunction with the Finite Element Model, for the solution of the nonlinear eigenvalue problem.

Highlights

In a wide range of applications taking place in the marine environment, including the analysis of marine structures, the study of coastal processes, as well as coastal and port engineering studies, information concerning the wave climate in nearshore and coastal areas is derived by offshore-to-nearshore transformation of wave conditions; e.g., [1,2]
The findings suggest that the incoming eastern waves through the open entrance were likely to excite port resonances
The identification of wave directions from a directional extreme value model that could result in intense resonance phenomena inside the port of Sitia was examined

Summary

Introduction

In a wide range of applications taking place in the marine environment, including the analysis of marine structures, the study of coastal processes, as well as coastal and port engineering studies, information concerning the wave climate in nearshore and coastal areas is derived by offshore-to-nearshore transformation of wave conditions; e.g., [1,2]. This is because local buoy measurements are usually not available at the site of interest, and reliable information from satellite measured data and operational wave models with global coverage and long duration are available at some distance from the coast [3].

Methods

Results

Conclusion