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Lowering the overall cost of wave energy converters is a necessity for creating a feasible solution to renewable energy. The design of wave energy converters is in general based on traditional steel design methods. In the design of steel structures subjected to significant dynamical loading and a harsh environment issues such fatigue resistance and durability are of major concern. The welded joints in steel structures significantly reduce the fatigue resistance and give a low utilization ratio of the steel material. Furthermore is coating of all exposed steel surfaces a necessity to secure a sufficient durability of the entire structure. Consequently it will be of great concern to optimize the structural concepts of the wave energy converters and secondly find materials tailored to the harsh environment at sea.The paper shows that utilizing Ultra High Performance Fibre Reinforced Concrete as primary material in the design of wave energy converters is a feasible and promising solution, which reduce the overall cost of the structure significantly. This will be illustrated by means of a feasibility study carried out on the Wavestar project, where special attention is pointed at the arm and float structure . The arm structure is previously designed as a steel structure, whereas the float has been designed as a light weight glass fibre structure. The new UHPFRC design gives a very beneficial solution that will contribute to the reduction of the manufacturing and the maintenance cost of the Wavestar wave energy converter.

In this paper, an optical non-contact low budget method for tracking the position of multi-object is presented for marine/off-shore laboratory applications. Particular focus is given at the wave energy field and the analysis of floating wave energy converters dynamics. The measurement of the position and orientation is often a key point in this context, achieved nowadays with different standard technologies. Typically a base requirement for a measurement system is to be accurate and precise, without affecting the dynamical and statical behavior of the system itself. Video based systems satisfy these points, but they are typically prohibitively expensive. Through the article a low budget one-camera video based system is presented and compared with other two standard methods: direct physical measurement and inertial motion unit (IMU). The system was tested both, in a dry environment and in waves. Results show an average error below 4%, with increased high signal accuracy and precision in the low frequency components but also increased high frequency noise components. Further investigation will be addressed to the implementation of a hybrid system, where the corrupted high frequency information can be replaced by the IMU signal.

Vicinanza, D., Norgaard, J.H., Contestabile, P. and Andersen, T.L., 2013. Wave loadings acting on Overtopping BReakwater for Energy Conversion. Any kind of Wave Energy Converter (WEC) requires information on reliability of technology and on time required for the return of the investment (reasonable payback). The structural response is one of the most important parameters to take in to account for a consistent assessment on innovative devices. This paper presents results on wave loading acting on an hybrid WEC named Overtopping BReakwater for Energy Conversion (OBREC). The new design is based on the concept of an integration between a traditional rubble mound breakwater and a front reservoir designed to store the wave overtopping from the incoming wave to produce electricity. 2D hydraulic model tests were carried out at the Department of Civil Engineering, Aalborg University (Denmark). The analyses of hydraulic model tests have identified the main shapes assumed by wave surfaces at the breakwater ...

The Seawave Slotcone Generator (WAVEnergy SAS, 2003) is a wave energy converter based on the overtopping principle. Although it has been effectively researched during the last decade, no design tool has been supplied to estimate the hydrodynamic loads the waves exert on its front face. In this article a set of well reliable 3D experiments has been re-analyzed, in order to get indications on possible calculation methods. It is shown that the Japanese design tools for monolithic sea dikes may be reasonably adapted to the present case. Finally a new approach is presented, which is based on the so called momentum flux principle ; the resulting predictive equation fits the experimental data remarkably well.

"New large-scale laboratory data are presented on the influence of long waves, bichromatic wave groups and random waves on sediment transport in the surf and swash zones. Physical model testing was performed in the large-scale CIEM wave flume at UPC, Barcelona, as part of the SUSCO (swash zone response under grouping storm conditions) experiment in the Hydralab III program (Vicinanza et al., 2010). Fourteen different wave conditions were used, encompassing monochromatic waves, bichromatic wave groups and random waves. The experiments were designed specifically to compare variations in beach profile evolution between monochromatic waves and unsteady waves with the same mean energy flux. Each test commenced with approximately the same initial profile. The monochromatic conditions were perturbed with free long waves, and then subsequently substituted with bichromatic wave groups with different bandwidth and with random waves with varying groupiness. Beach profile measurements were made at half-hourly and hourly intervals, from which net cross-shore transport rates were calculated for the different wave conditions. Pairs of experiments with slightly different bandwidth or wave grouping show very similar net cross-shore sediment transport patterns, giving high confidence to the data set. Consistent with recent small-scale experiments, the data clearly show that in comparison to monochromatic conditions the bichromatic wave groups reduce onshore transport during accretive conditions and increase offshore transport during erosive conditions. The random waves have a similar influence to the bichromatic wave groups, promoting offshore transport, in comparison to the monochromatic conditions. The data also indicate that the free long waves promote onshore transport, but the conclusions are more tentative as a result of a few errors in the test schedule and modifications to the setup which reduced testing time. The experiments suggest that the inclusion of long wave and wave group sediment transport is important for improved near-shore morphological modeling of cross-shore beach profile evolution, and they provide a very comprehensive and controlled series of tests for evaluating numerical models. It is suggested that the large change in the beach response between monochromatic conditions and wave group conditions is a result of the increased significant and maximum wave heights in the wave groups, as much as the presence of the forced and free long waves induced by the groupiness. The equilibrium state model concept can provide a heuristic explanation of the influence of the wave groups on the bulk beach profile response if their effective relative fall velocity is larger than that of monochromatic waves with the same incident energy flux."

This research describes a unique set of experiments undertaken at the Large Wave Channel (Hannover) aimed to study the morphodynamic behaviour of a beach face containing a buried drainage system. The advantage of using a large wave flume is that scale effects that affected previous laboratory experiments are minimized. This compares the response of the undrained beach under controlled wave forcing with the response of the drained one with the same wave action. Low, medium and high levels of wave energy were used for the experiments, with significant wave heights of 0.39–0.83 m and wave steepnesses between 0.004 and 0.013. Any positive effect of the drains on the beach face was confined by the position of the cone of depression in the aquifer surface. The best performance of the system was observed with two drains operating at the same time under low to moderate wave energy.

"The modelling of swash zone (SZ) sediment transport and the resulting morphodynamics have been areas of active research over the last decade. However, many details are still to be understood, whose knowledge will be greatly advanced by the collection of high-quality data under the controlled large-scale laboratory conditions. The research describes tests carried out in the large wave flume of the Maritime Engineering Laboratory at Catalonia University of Technology, to investigate the SZ under the storm conditions. Its main aim was to compare beach-profile responses for monochromatic waves, monochromatic waves plus free long waves, bi-chromatic waves and random waves. Both erosive and accretive conditions were considered. Results discussed here were derived from the analysis of only a part of the whole data set."

Chiaiolella Beach is a 1.5-km-long pocket beach located on Procida Island (Italy). The beach is formed by medium sand generated by erosion of vulcanoclastic rocks that form cliffs around the island and at the backshore of the study site. A beach dewatering system was installed in April 2002 to provide a wider beach for users and to prevent cliff undercutting during storms. It has not been operative since December 2004, as local authorities decided to undertake cliff stabilization measures. Surveys carried out immediately before (October 2001) and 1 year after installation (October 2002) showed negligible volumetric change on the drained beach in Ciraccio (−0.52 m3/m), the NNE sector of Chiaiolella Beach, whereas on the undrained control section there was an accumulation of 1.41 m3/m. Since no long-term monitoring of beach profiles was available at the site previous to installation, to obtain an indication of the nearshore hydrodynamics and morphodynamics in absence of the drain, historical shorel...

I sistemi di drenaggio delle spiagge (BDS) possono rappresentare, in alcuni casi, una possibile alternativa ai tradizionali sistemi rigidi per la difesa dei litorali dall’erosione costiera. Il sistema ha lo scopo di abbassare artificialmente la linea di falda, aumentando lo spessore della fascia insatura all’interno della spiaggia e favorendo l’infiltrazione del flusso di risalita e, quindi, il deposito dei sedimenti nella zona di swash. Nel presente lavoro sono descritti alcuni aspetti idrodinamici derivanti da un’attività sperimentale 2D in larga scala condotta presso il canale GWK di Hannover. In particolare, vengono analizzate le variazioni della water table e le portate drenate indotte da un particolare sistema costituito da 4 dreni installati all’interno della spiaggia e posti a distanza variabile dalla linea di riva. L’obiettivo della configurazione adottata, attraverso prove a regime statico e dinamico, è stato indirizzato alla verifica della posizione ottimale dei dreni. I risultati dedotti dalle analisi hanno mostrato l’efficacia dei dreni in termini di abbassamento della linea di falda, con conseguente aumento della zona insatura all’interno della spiaggia. Tuttavia, non è risultato possibile definire un’univoca correlazione tra l’abbassamento della linea di falda e la distanza dalla linea di riva dei dreni al fine di definire una loro corretta sistemazione planimetrica. Le ridotte portate drenate sono risultate essere dipendenti dal regime di moto a pelo libero che s’instaura all’interno dei dreni.

This paper presents results on loading acting on an innovative caisson breakwater for electricity production. The work reported here is part of the European Union Sixth Framework programme priority 6.1 (Sustainable Energy System), contract 019831, titled "Full-scale demonstration of robust and high-efficiency wave energy converter" (WAVESSG). Information on wave loadings acting on Wave Energy Convert (WEC) Seawave Slot-Cone Generator (SSG) exposed to extreme wave conditions are reported. The SSG concept is based on the principle of overtopping and storing the wave energy in several reservoirs placed one above the other. Comprehensive 2D and 3D wave tank model tests were carried out at the Department of Civil Engineering, Aalborg University (Denmark) in the 3D deep water wave tank. The model scale used was 1:60 of the SSG prototype at the planned location of a pilot plant at the west coast of the island Kvitsøy near Stavanger, Norway. The research study is intended to be of direct use to engineers analyzing design and stability of the pilot plant. This paper presents results on loading acting on an innovative caisson breakwater for electricity production. The work reported here is part of the European Union Sixth Framework programme priority 6.1 (Sustainable Energy System), contract 019831, titled "Full-scale demonstration of robust and high-efficiency wave energy converter" (WAVESSG). Information on wave loadings acting on Wave Energy Convert (WEC) Seawave Slot-Cone Generator (SSG) exposed to extreme wave conditions are reported. The SSG concept is based on the principle of overtopping and storing the wave energy in several reservoirs placed one above the other. Comprehensive 2D and 3D wave tank model tests were carried out at the Department of Civil Engineering, Aalborg University (Denmark) in the 3D deep water wave tank. The model scale used was 1:60 of the SSG prototype at the planned location of a pilot plant at the west coast of the island Kvitsøy near Stavanger, Norway. The research study is intended to be of direct use to engineers analyzing design and stability of the pilot plant.

This paper discusses a new type of Wave Energy Converter (WEC) named Seawave Slot-Cone Generator (SSG). The SSG is a WEC of the overtopping type. The structure consists of a number of reservoirs one on the top of each others above the mean water level in which the water of incoming waves is stored temporary. Using this method practically all waves, regardless of size and speed are captured for energy production. In each reservoir, expressively designed low head hydro-turbines are converting the potential energy of the stored water into electrical power. A key to success for the SSG will be low cost of the structure. The wave forces on the main structure can be estimated using experiences from coastal protection structures, but the differences between the structures are so large that more reliable knowledge on the wave forces is desired. The purpose of the work is to derive information on wave loadings acting on sloping walls constituting the structure. The research is intended to be of direct use to engineers analyzing design and stability of this peculiar kind of coastal structure. This paper discusses a new type of Wave Energy Converter (WEC) named Seawave Slot-Cone Generator (SSG). The SSG is a WEC of the overtopping type. The structure consists of a number of reservoirs one on the top of each others above the mean water level in which the water of incoming waves is stored temporary. Using this method practically all waves, regardless of size and speed are captured for energy production. In each reservoir, expressively designed low head hydro-turbines are converting the potential energy of the stored water into electrical power. A key to success for the SSG will be low cost of the structure. The wave forces on the main structure can be estimated using experiences from coastal protection structures, but the differences between the structures are so large that more reliable knowledge on the wave forces is desired. The purpose of the work is to derive information on wave loadings acting on sloping walls constituting the structure. The research is intended to be of direct use to engineers analyzing design and stability of this peculiar kind of coastal structure.

In recent years the hydraulic performance of low-crested structures has been widely studied both theoretically and through experimental analyses, but only a few studies have been focused on the combined diffraction-overtopping effects on wave transmission and induced wave currents. In this paper hydraulic model tests conducted at the 3D wave basin of Delft University of Technology ( Caceres et al., 2008 ) were used to obtain and discuss two simple methods for predicting the wave height at the lee of a single detached breakwater of finite length and the related current regime. For the first time diffraction effects are expressly accounted for. The agreement with experimental data is encouraging. The main objective of the paper is to aid engineers in the first stage of the design process, when using a mathematical model could be unnecessarily excessive.

The SSG (Sea Slot-cone Generator) is a wave energy converter of the overtopping type. The structure consists of a number of reservoirs one on the top of each other above the mean water level in which the water of incoming waves is stored temporary. In each reservoir, expressively designed low head hydro-turbines are converting the potential energy of the stored water into power. A key to success for the SSG will be the low cost of the structure and its robustness. The construction of the pilot plant is scheduled and this paper aims to describe the concept of the SSG wave energy converter and the studies behind the process that leads to its construction. The pilot plant is an on-shore full-scale module in 3 levels with an expected power production of 320 MWh/y in the North Sea. Location, wave climate and laboratory tests' results will be used here to describe the pilot plant and its characteristics.

In this paper, we present a model study on beach morphodynamic processes under the combined action of waves and controlled subsidence settlement. A special facility was designed to reproduce controlled seabed movements of a few millimetres. Vertical settlement is obtained with the use of wedges driven by the Archimedean screw. A prototype to model mechanical scale in this particular experiment showed the difficulties of reproducing a test duration that in the prototype could vary from 10 to 100 years. To solve this problem, tests were carried out reproducing only wave conditions able to give significant seabed movement. Measurements of wave heights, beach profiles, and shorelines were made. Results highlight the different effects of subsidence on beach profiles under storm surge, annual average wave conditions, and morphologic wave. Beach profiles and shorelines show a relevant increase in erosion, more evident in the vicinity of the still-water level because of the combined action of waves and s...

In addition to reducing the incoming wave energy, submerged breakwaters also cause a setup of the sea level in the protected area, which is relevant to the whole shadow zone circulation, including alongshore currents and seaward flows through the gaps. This study examines such a leading hydraulic parameter under the simplified hypothesis of 2D motion and presents a prediction model that has been validated by a wide ensemble of experimental data. Starting from an approach originally proposed by Dalrymple and Dean [(1971). Piling-up behind low and submerged permeable breakwaters. Discussion note on Diskin et al. (1970). Journal of Waterways and Harbors Division WW2, 423–427], the model splits the rise of the mean water level into two contributions: one is due to the momentum flux release forced by wave breaking on the structure, and the other is associated with the mass transport process. For the first time, the case of random wave trains has been explicitly considered.

Any kind of Wave Energy Converter (WEC) requires information on how optimize the device in terms of hydraulic performances and structural responses. This paper presents results on wave loading acting on an innovative caisson breakwater for electricity production. The Seawave Slot-Cone Generator (SSG) concept is based on the known principle of overtopping and storing the wave energy in several reservoirs placed one above the other. Using this method practically all waves, regardless of size and speed are captured for energy production. In the present SSG setup three reservoirs have been used. Comprehensive 2D and 3D hydraulic model tests were carried out at the Department of Civil Engineering, Aalborg University (Denmark) in the 3D deep water wave tank. The model scale used was 1:60 of the SSG prototype at the planned location of a pilot plant at the west coast of the Kvitsoy island (Stavanger, Norway). The analyses of hydraulic model tests have identified the main shapes assumed by wave surfaces at the breakwater and respective spatial and temporal pressure distributions. The influence of wave obliquity and multidirectionality is also described by loading reduction factors referred to the case of long-crested head-on wave attack. Pressure measurements were compared with the prediction method made for caisson breakwaters with sloping top. These results suggest to use the experimental data as design pressures since the design criteria of traditional maritime structures may be not satisfactory for designing innovative breakwater as SSG.

The SSG (Sea Slot-cone Generator) is a wave energy converter of the overtopping type. The structure consists of a number of reservoirs one on the top of each others above the mean water level, in which the water of incoming waves is stored temporary. In each reservoir, expressively designed low head hydroturbines are converting the potential energy of the stored water into power. A yearly energy production of 320 MWh is foreseen for a 10 meter wide section. A key to success for the SSG will be the low cost of the structure and its robustness. During the last 2 years such a 1350 tonnes concrete structure has been under detailed design in Norway. The construction was planned to be installed during spring and summer 2008 at a small island Kvitsoy situated near Stavanger. Unfortunately environmental issues have demanded a movement of the project to another location. The actual situation is that some breakwaters under design are being investigated as a possible places for integrating the SSG structure.The paper describes the concept of the SSG wave energy converter, the structure and the studies that led to its design. The SSG (Sea Slot-cone Generator) is a wave energy converter of the overtopping type. The structure consists of a number of reservoirs one on the top of each others above the mean water level, in which the water of incoming waves is stored temporary. In each reservoir, expressively designed low head hydroturbines are converting the potential energy of the stored water into power. A yearly energy production of 320 MWh is foreseen for a 10 meter wide section. A key to success for the SSG will be the low cost of the structure and its robustness. During the last 2 years such a 1350 tonnes concrete structure has been under detailed design in Norway. The construction was planned to be installed during spring and summer 2008 at a small island Kvitsoy situated near Stavanger. Unfortunately environmental issues have demanded a movement of the project to another location. The actual situation is that some breakwaters under design are being investigated as a possible places for integrating the SSG structure.The paper describes the concept of the SSG wave energy converter, the structure and the studies that led to its design.

Beach nourishment design requires a multi-disciplinary approach, the main aspect of design is related to a deep knowledge of the coastal zone and its processes to define: suitable kind of beach nourishment, characteristic of fill material and availability of submarine borrow sites. For an improved/integrated design need to be considered not only the Equilibrium Profile Theory and Depth of Closure, with their time-scale related aspects, but also environmental quality and suitability of resources. The most important beach nourishment problem it's to find a suitable site with high 'quality' material. In this paper the Authors underline that quality is not a strictly design concept but it's also referred to a more complex combination of sedimentologic, biogeochemical and environmental parameters whose equilibrium is sometimes difficult to define at the borrow site and at the eroded beach too. An integrated methodology is proposed to face the sand mining referring to sediment quality parameters definition.

Il lavoro è dedicato alla validazione di una formula sulla trasmissione ondosa a tergo di scogliere a cresta bassa che gli Autori hanno proposto sulla base di una estesa indagine sperimentale in grande scala svolta presso il Grosser WellenKanal (GWK) di Hannover, Germania.

This paper discusses wave loadings on vertical and composite walls, and related maritime / coastal structures. It presents new data on the magnitudes and probabilities of pulsating and impact loads from hydraulic model studies on a wide range of wall configurations, and compares the results with present prediction methods. Extensive model tests measured wave loads using realistic random wave conditions, without artificially forcing wave breaking or taking an extreme response from repeated regular waves. Results presented here identify the parameter regions within which impact or pUlsating loads may occur, and give example distributions of pressures. Results of these studies are intended to be used by engineers analysing the stability of vertical or composite walls in deep water, in harbours, near the coast or along the shoreline. Prediction methods and the test results discussed here may be used to estimate wave loadings on a variety of structures, existing or in design.

This paper discuss wave loadings acting on the Wave Energy Converter (WEC) Seawave Slot-Cone Generator (SSG). The SSG is a new type of structure for wave energy conversion based on storing the incoming waves in several reservoirs placed one above the other. The wave forces on the main structure can be estimated using experiences from coastal protection structures, but the differences between the two types of structures are so large that more reliable knowledge on the wave forces is desired. Model tests were carried out to measure wave loads using realistic random 2D and 3D wave conditions. Pressure cells were placed in order to achieve information on impact/pulsating loadings. Data analysis identifies different structure response depending on wall geometry and location. Results discussed here derive from preliminary analysis conducted using only a part of the whole data set. The research is intended to be of direct use to engineers analyzing design and stability of the pilot plant under construction at Kvitsøy island, partly funded by the EU 6th framework program (WAVESSG). This paper discuss wave loadings acting on the Wave Energy Converter (WEC) Seawave Slot-Cone Generator (SSG). The SSG is a new type of structure for wave energy conversion based on storing the incoming waves in several reservoirs placed one above the other. The wave forces on the main structure can be estimated using experiences from coastal protection structures, but the differences between the two types of structures are so large that more reliable knowledge on the wave forces is desired. Model tests were carried out to measure wave loads using realistic random 2D and 3D wave conditions. Pressure cells were placed in order to achieve information on impact/pulsating loadings. Data analysis identifies different structure response depending on wall geometry and location. Results discussed here derive from preliminary analysis conducted using only a part of the whole data set. The research is intended to be of direct use to engineers analyzing design and stability of the pilot plant under construction at Kvitsøy island, partly funded by the EU 6th framework program (WAVESSG).

Despite wave set up onshore low crested breakwaters may reveal quite important for the functional design of these structures, the experimental studies on this topic are up to now extremely limited, especially under random wave attacks. This contribution discusses results of large scale model tests the Authors conducted at the Grosser WellenKanal (GWK) of Hannover, Germany on an idealized 2D model of low crested/submerged breakwater. Analysis showed the importance of momentum release of breaking waves for submerged breakwaters and of the mass balance for low crested ones.

This note describes the influence of wave spreading, directionality and local bathymetry on the efficiency of the SSG wave energy converter Pilot plant in Kvitsøy, Norway. This is an overtopping device i.e. its efficiency is directly proportional to the overtopping flows in the three reservoirs the device has one on top of each others. The overtopping flow rates have been measured separately for each one of them, together with incoming waves during physical model tests at Aalborg University. The influence of the significant wave height Hs and of the wave length L on the captured overtopping water is also described. It has been found that the performance of the SSG Pilot will be negatively affected by spreading and directionality of the incoming waves as direct consequence of reduction on the overtopping flow rates of 10% - 35% compared to 2D conditions. This note describes the influence of wave spreading, directionality and local bathymetry on the efficiency of the SSG wave energy converter Pilot plant in Kvitsøy, Norway. This is an overtopping device i.e. its efficiency is directly proportional to the overtopping flows in the three reservoirs the device has one on top of each others. The overtopping flow rates have been measured separately for each one of them, together with incoming waves during physical model tests at Aalborg University. The influence of the significant wave height Hs and of the wave length L on the captured overtopping water is also described. It has been found that the performance of the SSG Pilot will be negatively affected by spreading and directionality of the incoming waves as direct consequence of reduction on the overtopping flow rates of 10% - 35% compared to 2D conditions.

This paper intends contributing to an economically and environmentally sustainable development of coastal infrastructures by investigating the possibility of combining together breakwaters and Wave Energy Converters (WEC). The latter change the wave energy to electricity, which may serve both the rubble mound breakwaters and seawalls related activity and the energy demand of small human communities. Wave loadings and overtopping on a seawall and rubble mound breakwater with front reservoir are discussed on the basis of physical 2-D model tests carried out at University of Southampton (UK) and Aalborg University (DK). This paper intends contributing to an economically and environmentally sustainable development of coastal infrastructures by investigating the possibility of combining together breakwaters and Wave Energy Converters (WEC). The latter change the wave energy to electricity, which may serve both the rubble mound breakwaters and seawalls related activity and the energy demand of small human communities. Wave loadings and overtopping on a seawall and rubble mound breakwater with front reservoir are discussed on the basis of physical 2-D model tests carried out at University of Southampton (UK) and Aalborg University (DK).

The accuracy of directional wave spectra sensors is crucial for obtaining accurate forecasts of ocean and coastal wave conditions for scientific and engineering applications. In this paper, a newly designed, low-cost GPS-based wave buoy, called the Directional Wave Spectra Drifter (DWSD), is presented. A field test campaign was conducted at the Gulf of Naples, Italy with the goal of comparing the directional wave properties obtained with the DWSD and with a nearly co-located bottom-mounted Acoustic Doppler Current Profiler (ADCP) from Teledyne RD-Instruments. The comparison shows a very good agreement between the two methodologies. The reliability of this innovative instrument and its low costs allow a large variety of applications, including the implementation of a global, satellite-linked, real-time open-ocean network of drifting directional wave spectra sensors and monitoring the sea-state in harbors to aid ship transit and for planning coastal and offshore constructions. The DWSD is currently in use to better constrain the wave energy climatology with the goal of optimizing the design of a full-scale prototype Wave Energy Converter (WEC) in the port of Naples, Italy.

In 2008 the authors verified the hydraulic stability of a coastal defense project to be built along the NW coast of Sicily (Italy, Tomasicchio et al., 2009). The intervention consisted of shore parallel barriers armored with a relatively new eco-friendly system: ECOPODETM. In that context the idea arose of conducting an exhaustive experimental campaign on the “ hydraulic response “ of these units, including wave run-up , wave overtopping, wave transmission and wave reflection observations. The latter has been performed in 2010 at the LInC Laboratory of University of Naples “Federico II”. In this paper results on wave run-up and reflection are presented and discussed.

Seismic stratigraphy and core litho-stratigraphy in the Salerno Bay inner shelf (Southern Tyrrhenian Sea) reveal significant storm deposition episodes over the last 1 ky. Three major events are preserved as decimetre thick silt/sand layers bounded at their base by erosional surfaces and sealed in the muddy marine sequences between 25 and 60 m of depth. Geochronology and chrono-stratigraphy on core sediment point towards a recurrence of major sea storms between 0.1 and 0.3 ky and put the last significant event in the 19th century, when no local meteorological time series is available. A modelling of extreme sea-storms with a return period of about 0.1 ky is here proposed based on historical hindcast and aims at explaining the occurrence of such unusual deep and thick sand deposits in the northern sector of the bay. Results highlight the vulnerability of the northern coast of the Salerno Bay to the south western sea storms which can drive waves up to about 8 m high and wave period of about 13 s. With these conditions an intense combined flow current is formed and might account for winnowing fine sand down to the depth of 40 m at least. The numerical model thus confirms a possible sand transport in the bottom boundary layer due to wave-current interaction and could corroborate the interpretation of the most recent sand layers, included in the cores, as being generated under extreme sea storm conditions.

Hydraulic performance of low crested structures have been widely studied both theoretically and through experimental analyses; yet only few indication are available on the interaction between the main transmission modes (overtopping , filtration) and wave diffraction. Starting from the analysis of hydraulic model tests conducted at the 3D wave basin of Delft University of Technology, the paper investigates the spatial distribution of the transmitted wave energy due to both wave overtopping and diffraction and discusses the corresponding change of the power spectrum functions.