Modeling of Climate Change Effects on Coastal Erosion

Sediment Transport and Morphodynamic

Modelling of Harbour and Coastal Structures

The world’s coasts are being continuously reshaped by the interplay between natural- and human-induced pressures [...

An Integrated Numerical Model for the Design of Coastal Protection Structures

In the present work, an integrated coastal engineering numerical model is presented. The model simulates the linear wave propagation, wave-induced circulation, and sediment transport and bed morphology evolution. It consists of three main modules: WAVE_L, WICIR, and SEDTR. The nearshore wave transformation module WAVE_L (WAVE_Linear) is based on the hyperbolic-type mild slope equation and is valid for a compound linear wave field near coastal structures where the waves are subjected to the combined effects of shoaling, refraction, diffraction, reflection (total and partial), and breaking. Radiation stress components (calculated from WAVE_L) drive the depth averaged circulation module WICIR (Wave Induced CIRculation) for the description of the nearshore wave-induced currents. Sediment transport and bed morphology evolution in the nearshore, surf, and swash zone are simulated by the SEDTR (SEDiment TRansport) module. The model is tested against experimental data to study the effect of representative coastal protection structures and is applied to a real case study of a coastal engineering project in North Greece, producing accurate and consistent results for a versatile range of layouts

Numerical Simulation of Scour Depth and Scour Patterns in Front of Vertical-Wall Breakwaters Using OpenFOAM

An advanced coupled numerical model was developed and implemented in the present work, describing the scour patterns and predicting the scour depth in front of vertical-wall breakwaters. It consists of two independent models, a hydrodynamic Computational Fluid Dynamics (CFD) Reynolds Averaged Navier–Stokes (RANS) model developed on the OpenFOAM (version 2.4.0) toolbox (CFD), describing the wave propagation and the associated hydrodynamic field, and a morphodynamic one (sediment transport model), which was developed in FORTRAN by the authors and yields the updated seabed morphology. The method used here is iterative. The hydrodynamic model is applied for any given initial seabed geometry and wave conditions, resulting in the hydrodynamic field of the flow, which is used as input by the second sediment transport model for the seabed morphology evolution. This process is repeated until the equilibrium profile is achieved. Model results are compared satisfactorily with experimental data for both scour patterns and prediction of scour depth

Boussinesq modeling of wave run-up and overtopping

Proceedings of the Seventh International Conference on Hydroscience and Engineering, Philadelphia, PA, September 2006. http://hdl.handle.net/1860/732In this study, wave overtopping of coastal structures in the surf zone is investigated numerically. Simulations are performed with the use of a Boussinesq-type model. The model incorporates high-order equations with improved dispersion characteristics. These equations are capable of modeling dispersive wave propagation even in deep water conditions. Wave breaking and bottom friction are also included in the model while a linear extrapolation technique is used to describe wave run-up on steep slopes. Model results are evaluated using experimental measurements conducted in wave flumes. Tests involving wave run-up on a plane beach and wave overtopping of permeable and impermeable breakwaters are considered. The analysis demonstrates that the model results had good agreements with the experiments except for some deficiencies in cases of complex flow structures

Simulation of tsunami generation, propagation and coastal inundation in the Eastern Mediterranean.

In the present work, an advanced tsunami generation, propagation and coastal inundation 2-DH model (i.e. 2-D Horizontal model) based on the higher-order Boussinesq equations - developed by the authors - is applied to simulate representative earthquake-induced tsunami scenarios in the Eastern Mediterranean. Two areas of interest were selected after evaluating tsunamigenic zones and possible sources in the region: one at the southwest of the island of Crete in Greece and one at the east of the island of Sicily in Italy. Model results are presented in the form of extreme water elevation maps, sequences of snapshots of water elevation during the propagation of the tsunamis, and inundation maps of the studied low-lying coastal areas. This work marks one of the first successful applications of a fully nonlinear model for the 2-DH simulation of tsunami-induced coastal inundation; acquired results are indicative of the model's capabilities, as well of how areas in the Eastern Mediterranean would be affected by eventual larger events

Assessment of island beach erosion due to sea level rise: The case of the Aegean Archipelago (Eastern Mediterranean)

The present contribution constitutes the first comprehensive attempt to (a) record the spatial characteristics of the beaches of the Aegean Archipelago (Greece), a critical resource for both the local and national economy; and (b) provide a rapid assessment of the impacts of the long- term and episodic sea level rise (SLR), under different scenarios. Spatial information and other attributes (e.g. presence of coastal protection works and backshore development) of the beaches of the 58 largest islands of the Archipelago were obtained on the basis of remote-sensed images available in the web. Ranges of SLR-induced beach retreats under different morphological, sedimentological and hydrodynamic forcing and SLR scenarios were estimated, using suitable ensembles of cross-shore (1-D) morphodynamic models. These ranges, combined with empirically-derived estimations of wave run up-induced flooding, were then compared with the recorded maximum beach widths, to provide ranges of retreat/erosion and flooding at the Archipelago scale. The spatial information shows that the Aegean beaches may be particularly vulnerable to mean (MSLR) and episodic SLRs due to: (i) their narrow widths (about 59 % of the beaches have maximum widths < 20 m); (ii) their limited terrestrial sediment supply; (iii) the substantial coastal development and (iv) limited existing coastal protection. Modeling results indeed project severe impacts under MSLR and storm surges, which by 2100 could be devastating. For example, under MSLR of 0.5 m (RCP4.5), a storm surge of 0.6 m is projected to result in complete erosion of between 31 and 88 % of all beaches (29 - 87 % of beaches currently fronting coastal infrastructure and assets), at least temporarily. It appears that, in addition to the significant effort and financial resources required to protect/maintain the critical economic resource of the Aegean Archipelago, appropriate coastal ‘set-back zone’ policies should also be adopted and implemented.JRC.E.1-Disaster Risk Managemen

Validation and Application of the Accu-Waves Operational Platform for Wave Forecasts at Ports

This paper presents a recently developed Operational Forecast Platform (OFP) for prevailing sea conditions at very important ports worldwide (Accu-Waves). The OFP produces reliable high-resolution predictions of wave characteristics in and around ocean ports. Its goal is to support safer navigation, predict possible port downtime, assist vessel approaching, enhance management of towing services, and bolster secure ship maneuvering in busy ports around the globe. Accu-Waves OFP is based on integrated, high-resolution wave modelling over the continental shelf and in coastal areas that incorporates data from global- and regional-scale, open-sea wave and ocean circulation forecasts as boundary conditions. The coupling, nesting, calibration, and implementation of the models are reported and discussed in this paper, concerning 50 selected areas near and inside significant port basins. The detailed setup of the Accu-Waves OFP and its sub-system services is also provided regarding three-day forecasts at three-hourly intervals. The validation of the wave forecast system against in situ observations from wave buoys in coastal areas of the USA, Belgium, and Spain, as well as other model predictions by established OFPs, seems very promising, with performance skill scores ranging from adequate to very good. An exceptional case of stormy seas under severe marine weather conditions with very high wave maxima (>10 m) in the port of Algeciras is further discussed, confirming the good performance of the Accu-Waves OFP