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This paper is the product of the wave modelling community and it tries to make a picture of the present situation in this branch of science, exploring the previous and the most recent results and looking ahead towards the solution of the problems we presently face. Both theory and applications are considered. The many faces of the subject imply separate discussions. This is reflected into the single sections, seven of them, each dealing with a specific topic, the whole providing a broad and solid overview of the present state of the art. After an introduction framing the problem and the approach we followed, we deal in sequence with the following subjects: (Section) 2, generation by wind; 3, nonlinear interactions in deep water; 4, white-capping dissipation; 5, nonlinear interactions in shallow water; 6, dissipation at the sea bottom; 7, wave propagation; 8, numerics. The two final sections, 9 and 10, summarize the present situation from a general point of view and try to look at the future developments.

The high fidelity simulation of littoral environments (HFSoLE) challenge project (C75) encompasses a suite of seven oceanographic models capable of exchanging information in a physically meaningful sense across the littoral environment. This project is leveraging and extending state-of-the-art atmospheric, oceanographic, estuarine, riverine, surface water/groundwater, and sediment transport models to provide DoD with the technology capable of rapidly characterizing the littoral environment. Applications of these models include real world scenarios such as predicting the ocean currents off the Spanish Coast after the prestige oil spill and generating diver visibility maps for the Persian Gulf. These models and their inputs have been finely tuned, tested, analyzed, and coupled with the use of HPC challenge time.

This note presents laboratory experiments conducted in a wave-current flume, concerning piling-up and filtration at low crested rubble-mound breakwaters of different permeability. The experiments tested 4 barrier geometries, 2 water depths, 5 irregular waves and 2 barrier materials for a total of 80 test cases. The experimental apparatus permits a simple and accurate measurement of the total water inshore flux induced by the wave loads, overtopping and filtration through the barrier crest. Original measurements are presented.

A semi-empirical model is developed for prediction of wave heights pdf in shallow waters. It assumes that a single Weibull distribution holds both in shoaling waters and in the surf zone. Pdf parameters have been linked to water depth and zero-moment of wave spectrum. The model has been calibrated using small scale experiments conducted at the University of Naples and has been validated on data from large scale tests performed at the Grosser WellenKanal (GWK) of Hannover, Germany. A comparison has been done with Composite Weibull Distribution (CWD) proposed by Battjes and Groenendijk (2000). The model seemed to be slightly more accurate in predicting commonly used wave height statistics, except for those with very low exceedence level within the surf zone

Functional design of low crested breakwaters requires an accurate prediction of wave transmission in the protected areas. Nevertheless, commonly used formulae do not appear to be reliable enough, especially for structures located in shallow waters. The paper describes results from large-scale model tests conducted on rubble mound breakwaters exposed to breaking waves. Tests were carried out at the "Grosser WellenKanal" of Hannover, Germany. The model dimension, near to prototype, allowed minimizing scale effects connected to wave breaking. Existing formulas on wave transmission have been verified and influence of crest width and breaker index have been highlighted

This note presents a method for producing coastal flooding hazard maps and its application to Lido delle Nazioni (Ferrara, Italy). The application is not part of a supported investigation but a mere example, the area being selected since a detailed altimetry was available, even though no specific information on dune resistance could be obtained. Some simplifying assumption are therefore made, the most strict being that flooding is only induced by overtopping, i.e. in the absence of dune breaching. MIKE21 flexible mesh tool is used for simulating several flooding scenarios induced by different combinations of waves and tide. By interpolating simulation results, a level II analysis based on the First Order Reliability Method (FORM) is used to produce maps giving the annual probability that flood level exceeds a given threshold. For instance, the most exposed urbanised areas have an yearly probability of 0.2% that flooding exceeds 1.0 m (0.01% that flooding exceeds 2.0 m). Hazard maps, usually evaluated by engineers, are the first step required to produce quantitative risk maps, for which also socio-economic expertise is needed.