Storm Energy Flux Characterization along the Mediterranean Coast of Andalusia (Spain)

This paper investigates wave climate and storm characteristics along the Mediterranean coast of Andalusia, for the period 1979&ndash

Caracterización y evolución del sistema playa-duna de la costa mediterránea de Andalucía (España): influencia de procesos naturales y actuaciones antrópicas

En las últimas décadas, los impactos relacionados con la erosión costera en las costas del mundo han aumentado significativamente debido al actual desarrollo costero y a la ocupación turística, así como a los eventos naturales de erosión/inundación acelerados por el cambio climático. Las costas oceánicas son entornos muy dinámicos y cambiantes, ya que muestran una gran variabilidad temporal y espacial en respuesta a la acción de diferentes y complejos procesos costeros. Esta variabilidad a escala temporal interanual está relacionada con las variaciones climáticas estacionales del oleaje, debido a distribuciones temporales y espaciales de tormentas de alta latitud y tormentas/huracanes tropi…

Dinamica costiera: individuazione della linea di riva e stima della sue incertezze

La linea di riva, ha natura dinamica, ovvero è sottoposta a continui cambiamenti, a breve e lungo termine, causati da processi geomorfologici, idrodinamici e da fattori improvvisi e rapidi. La ricerca esamina le problematiche legate all’incertezza nell’individuazione della posizione della linea di riva, al variare del tempo, considerando sia aspetti geologico - geomorfologici che aspetti idraulico marittimi. Il caso studio è un tratto di costa marsalese (Trapani). Tale settore è caratterizzato da una costa bassa con sedimenti sabbiosi d'età olocenica. L’analisi diacronica è stata basata su ortofoto e cartografie per il periodo di tempo compreso tra il 1994 e il 2006. È da precisare che la m…

A regional approach for exploring the relation between sediment transport and coastal erosion in Sicily

To study on a regional basis, the relation between fluvial sediment delivery and coastal erosion, the historical record of coastline migration of Sicily was analyzed with respect to the estimated sediment delivery to the coast obtained from the spatially distributed sediment delivery WaTEM/SEDEM model. The latter was directly acquired from the ESDAC database as a 25 m pixel layers, being based on the combination between the RUSLE model and a transport capacity routing algorithm. At the same time, the coastline-evolution (accretion/retreatment) data for 1960/1994 and 1994/2012 intervals were processed. This dataset, provided by ISPRA (Italian Institute for Environmental Protection and Resear…

Flow hydraulic characteristics determining the occurrence of either smooth or abrupt sewer pressurization

Laboratory experiments showed that pipe pressurization consequent on a drastic reduction in the downstream discharge can occur either by a gradual rising of the free-surface (“smooth” pressurization) or by propagation of a front filling the whole cross-section (“abrupt” pressurization). This study examines the free-surface flow characteristics that determine smooth or abrupt pressurization pattern through a theoretical approach using dimensionless variables. A critical flow rate value, which separates the pressurization patterns, exists for any given pipe diameter. For flow rates higher than this specific value, only abrupt pressurization occurs. For lower flow rates, either smooth or abrup…

Efficiency of Wave Energy Converters off the Sicilian Channel

This paper presents a preliminary analysis on efficiency of wave energy converters off the Sicilian Channel (Italy) carried out using the SNL-SWAN spectral model (”Sandia National Laboratories – Simulating WAves Nearshore”). This open source numerical code makes possible to calculate the power extracted from wave energy converter (WEC) devices, arranged in arrays. The WEC arrays were located parallel to the coastline, near the 20 m bathymetric isoline. Three devices were tested: Pelamis, Wave Dragon and Oyster 2; one of the input data of the numerical model is the WEC power matrix, expressed as a function of the wave height and period. This matrix was determined experimentally by the protot…

A Methodological Approach to Determine Sound Response Modalities to Coastal Erosion Processes in Mediterranean Andalusia (Spain)

Human occupation along coastal areas has been greatly increasing in recent decades and, in many places, human activities and infrastructures are threatened by erosion processes that can produce relevant economic and human losses. In order to reduce such impacts and design sound management strategies, which can range from the &ldquo

Run-up over variable slope bottom. Validation for a weakly nonlinear Boussinesq-type of model.

Analysis of wave energy conversion process

Since wave energy conversion technologies are developing due to the depletion of fossil fuels and due to their hazardous effects on the environment, an important and unexploited source of energy is wave energy. The paper proposes to compare theoretical data obtained using specialized software and data obtained via laboratory measurements using a scale model, regarding the mechanical torque generated at the axis of the electric motor. The data collected represent the kinetic and potential energy, simulating Black Sea waves using an installation proposed to be patented, an installation that converts off-shore wave energy.

Uncertainties in shoreline position analysis: the role of run-up and tide in a gentle slope beach

Abstract. In the last decades in the Mediterranean sea, high anthropic pressure from increasing economic and touristic development has affected several coastal areas. Today the erosion phenomena threaten human activities and existing structures, and interdisciplinary studies are needed to better understand actual coastal dynamics. Beach evolution analysis can be conducted using GIS methodologies, such as the well-known Digital Shoreline Analysis System (DSAS), in which error assessment based on shoreline positioning plays a significant role. In this study, we propose a new approach to estimate the positioning errors due to tide and wave run-up influence. To improve the assessment of the wav…

Shoreline detection in gentle slope Mediterranean beach

I grandi vincoli di un piccolo fiume. Notizie sulle interazioni fra l’Oreto e Palermo.

Applicazione alla verifica delle reti di condotte in una rivisitazione del capitolo del moto uniforme turbolento nelle correnti liquide

Una formula pseudo lineare esprime l’equazione del moto uniforme turbolento di un liquido viscoso, e consente di risolvere fedelmente, senza iterazioni né ricorsi a grafici o a tabelle, entrambi i “problemi di verifica” delle correnti nei tubi e si presta bene al “problema di progetto”. Il risultato è dovuto al ruolo di un nuovo parametro che aggiunto a quello che surroga la scabrezza relativa costituisce una coppia caratterizzante il sistema tubo scabro - liquido viscoso. Entrambi intervengono nella legge di resistenza di Colebrook-White ridotta ad una forma facile a ricordarsi e avente il significato concettuale di misurare il rapporto fra due variabili numeriche: esse sono proporzionali …

Analisi statistica della marea meteorologica sui tre versanti siciliani

La progettazione di porti, di opere di difesa e di protezione dei litorali e la pianificazione delle attività umane sulla costa richiedono una buona conoscenza delle fluttuazioni del livello del mare. Quest’ultimo è determinato dalla somma di due contributi principali: la marea astronomica, che essendo periodica è di facile predizione, e quella meteorologica, che viene considerata aleatoria. Nel presente lavoro, a partire dalle misure del livello idrico registrate dai mareografi dei porti di Catania, Palermo e Porto Empedocle nel periodo 1999-2010, sono state ricostruite le rispettive maree meteorologiche ed analizzate statisticamente al fine di trovare la migliore distribuzione di probabil…

Uncertainties in shoreline position analysis: the role of run-up and tide in a gentle slope beach

Abstract. In recent decades in the Mediterranean Sea, high anthropic pressure from increasing economic and touristic development has affected several coastal areas. Today the erosion phenomena threaten human activities and existing structures, and interdisciplinary studies are needed to better understand actual coastal dynamics. Beach evolution analysis can be conducted using GIS methodologies, such as the well-known Digital Shoreline Analysis System (DSAS), in which error assessment based on shoreline positioning plays a significant role. In this study, a new approach is proposed to estimate the positioning errors due to tide and wave run-up influence. To improve the assessment of the wave…

A non-hydrostatic pressure distribution solver for the nonlinear shallow water equations over irregular topography

Abstract We extend a recently proposed 2D depth-integrated Finite Volume solver for the nonlinear shallow water equations with non-hydrostatic pressure distribution. The proposed model is aimed at simulating both nonlinear and dispersive shallow water processes. We split the total pressure into its hydrostatic and dynamic components and solve a hydrostatic problem and a non-hydrostatic problem sequentially, in the framework of a fractional time step procedure. The dispersive properties are achieved by incorporating the non-hydrostatic pressure component in the governing equations. The governing equations are the depth-integrated continuity equation and the depth-integrated momentum equation…

Revisione critica del modello SMB attraverso un caso studio nel mediterraneo

Analysis of tide measurements in a Sicilian harbour

Designing of ports and coastal protection works as well as planning of coastal human activities require knowledge of tidal oscillations. The latter vary noticeably from site to site and present an “astronomic” component, which is roughly periodic, and a “meteorological” component which is usually considered as random. In this paper, the tidal oscillations observed in a Sicilian harbour in the period 1999-2009 are analysed statistically, in order to recognize a probability distribution which allows one to predict the highest tidal levels. First, the measurements are used to obtain, for each year, the astronomic tide by the harmonic analysis by the software package T_TIDE. The difference betw…

Coastal dynamics: shoreline detection in a Sicilian beach

The opportunity of using wave energy converters in a Mediterranean hot spot

The opportunity of using wave energy converter arrays in a hot spot area of the Mediterranean sea was investigated. For this purpose, numerical simulations of wave energy converters together with a simple cost-effective analysis were carried out. The selected study area is one of the most energetic inside the Sicilian channel (Italy). The numerical simulations were performed using the SNL-SWAN (“Sandia National Laboratories – Simulating WAves Nearshore”) spectral model with an unstructured mesh. The power absorbed from thirteen Wave Energy Converter (WEC) devices was computed. In particular, Pelamis, Wave Dragon, Oyster 2, Wavestar, B-HBA, B-OF, Bref-HB, Bref-SHB, F–2HB, F–3OF, F-HBA and F-…

Idrogeologia e crisi ecologica di un piccolo bacino endoreico

A new shoreline change assessment approach for erosion management strategies

Shoreline evolution studies are fundamental to assess the rate of beach accretion or retreatment. In the last years, researchers developed many methods with several techniques belonging to different disciplines and backgrounds. Nowadays, the Shoreline Change Analysis (SCA) is the most widespread method to assess shoreline evolution. In fact, the SCA is needed to perform management strategies able to respond to current erosion or potential future erosion problems. This paper presents a new approach using an automatic method for SCA with accuracy and speed improvements. Indeed, in the framework of the management of coastal erosion and to develop an adaptation plan to coastal hazards it is nec…

Wave Energy Assessment around the Aegadian Islands (Sicily)

This paper presents the estimation of the wave energy potential around the Aegadian islands (Italy), carried out on the basis of high resolution wave hindcast. This reanalysis was developed employing Weather Research and Forecast (WRF) and WAVEWATCH III ® models for the modelling of the atmosphere and the waves, respectively. Wave climate has been determined using the above-mentioned 32-year dataset covering the years from 1979 to 2010. To improve the information about wave characteristics regarding spatial details, i.e., increasing wave model resolution, especially in the nearshore region around the islands, a SWAN (Simulating WAves Nearshore) wave propagation model was used. Results obtai…

Field run-up measurements: Calibration of a physically based lagrangian shoreline model

In the present contribution a measurement technique based on video imaging has been selected for the assessment of the maximum run-up. Such measurements have been used for the calibration of a numerical model and of an empirical formulation. The on-site run-up measurements have been carried out at “Lido Signorino” beach, near Marsala, Italy. The positions of the swash have been localized on a transect, normal to the shore, constituted by stakes placed at 0.5 m intervals each other. The video camera was placed orthogonally to the line of the stakes. For the numerical simulations a 1DH Boussinesq-type of model for breaking waves has been applied which takes into account the wave run-up by a L…

Tsunami Propagation and Flooding in Sicilian Coastal Areas by Means of a Weakly Dispersive Boussinesq Model

This paper addresses the tsunami propagation and subsequent coastal areas flooding by means of a depth-integrated numerical model. Such an approach is fundamental in order to assess the inundation hazard in coastal areas generated by seismogenic tsunami. In this study we adopted, an interdisciplinary approach, in order to consider the tsunami propagation, relates both to geomorphological characteristics of the coast and the bathymetry. In order to validate the numerical model, comparisons with results of other studies were performed. This manuscript presents first applicative results achieved using the weakly dispersive Boussinesq model in the field of tsunami propagation and coastal inunda…

Masonry structures subjected to tsunami loads: Modeling issues and application to a case study

Abstract Tsunamis are among the most dangerous natural disasters for coastal areas experiencing tsunami hazard. One of the major concerns in the assessment of strategies for the risk mitigation is to estimate vulnerability of structures and infrastructures. However, reliable approaches for the evaluation of the structural capacity under tsunami loads are nowadays not always available for all the types of structures, especially masonry. On this aim, the paper deals with the modeling issues of 3D masonry structures subjected to tsunami loads and the effect on the structural behavior of different modeling approaches. First, a brief state of the art on the available studies is presented regardi…

Swash oscillation with a highly nonlinear Boussinesq model for breaking waves

Analisi statistica della velocità del vento nel Canale di Sicilia

Implementation of a software about the probability theory of reservoirs.

Oscillazioni della linea di riva in modelli alla Boussinesq

A shoreline boundary condition for a highly nonlinear Boussinesq model for breaking waves

Abstract A physically based strategy was used to model swash zone hydrodynamics forced by breaking waves within a Boussinesq type of model. The position and the velocity of the shoreline were determined continuously in space by solving the physically-based equations of the shoreline motion; moreover, a fixed grid method, with a wet–dry interface, was adopted for integrating the Boussinesq model. The numerical stability of the model was improved by means of an extrapolation method. To validate the proposed methodology, the classical analytical solution for the shoreline motion of a monochromatic wave train over a plane beach was considered. The comparison between the analytical and numerical…

Coupling a hydro-maritime model and remotely sensed techniques to assess the shoreline positioning uncertainty: the Marsala coast study case

The severe erosion phenomena affecting the Mediterranean coasts are strictly related to geophysical characteristics and socio-economic pressures. This suggests the need of monitoring and modelling the phenomenon in order to quantify its strength. In fact, the shoreline position, as well as its temporal evolution, provides important information for designing defence structures and for the development of a coastal management plan. The shoreline has a dynamic nature as it changes both in the short and long period. Those changes are caused by geo-morphological (e.g. bars and barrier island development etc.) and hydrodynamic (wave motion, tides and flows) processes, as well as by sudden and fast…

Oscillazioni della linea di riva in presenza di frangimento

Dune systems' characterization and evolution in the andalusia mediterranean coast (Spain)

This paper deals with the characterization and evolution of dune systems along the Mediterranean coast of Andalusia, in the South of Spain, a first step to assess their relevant value in coastal flood protection and in the determination of sound management strategies to protect such valuable ecological systems. Different dune types were mapped as well as dune toe position and fragmentation, which favors dune sensitivity to storms&rsquo

RESPONSE OF POSIDONIA OCEANICA TO WAVE MOTION IN SHALLOW-WATERS - PRELIMINARY EXPERIMENTAL RESULTS

Aim of the present work is to contribute to the knowledge about the interaction between the flow induced by wave and the aquatic vegetation. More in details the results of preliminary tests of an experimental laboratory investigation about the response of a Posidonia Oceanica meadow to wave motion in shallow waters is reported. A wide attention was posed to the behavior of a synthetic plants with plastic material. To this aim an image acquisition technique was used to analyze and compare the movement of both the artificial plant and the real one. The experiments carried out about the interaction between the artificial meadow and the waves showed a significant wave dumping, in particular in …

ANALYSIS OF THE RELATION BETWEEN THE FLOW “HORIZONTAL” TURBULENCE AND THE BED DEFORMATION

An Approach for the Validation of a Coastal Erosion Vulnerability Index: An Application in Sicily

In recent decades, coastal erosion phenomena have increased due to climate change. The increased frequency and intensity of extreme events and the poor sediment supply by anthropized river basins (dams, river weirs, culverts, etc.) have a crucial role in coastal erosion. Therefore, an integrated analysis of coastal erosion is crucial to produce detailed and accurate coastal erosion vulnerability information to support mitigation strategies. This research aimed to assess the erosion vulnerability of the Sicilian coast, also including a validation procedure of the obtained scenario. The coastal vulnerability was computed by means of the CeVI (Coastal Erosion Vulnerability Index) approach, whi…

Storm sewer pressurization transient – an experimental investigation

Pipe pressurization is examined experimentally by 144 laboratory experiments in a circular tilting pipe between two tanks, in which the transient was triggered by sudden closing of the downstream tank outlet. The experiments cover ranges of values of slope, velocity and filling ratio of the open-channel flow not explored in previous studies. Situations involving considerable air quantity and consequent intense pressure oscillations were also reproduced. Two different pressurization patterns, defined as “smooth” and “abrupt”, were observed, but only the abrupt pattern produced intense pressure oscillations. The comparison among all the abrupt pressurization surges showed how the oscillations…

A Shoreline model for breaking waves

In order to simulate the wave motion and, in turn, the flow, within the nearshore region, in the last decades the derivation and the application of depth-integrated type of models have been widely investigated and developed. However, in such models, the problems of facing wave breaking and the moving shoreline are not trivial and therefore several approaches have been proposed. About wave breaking, approaches both based on the adoption of an artificial eddy viscosity Zelt (1991) and on the concept of roller Veeramony (2000), Karambas (2003), Musumeci (2005) have been implemented. As regards the shoreline boundary condition, a couple of numerical techniques have been mainly adopted, namely t…

Present-day use of an empirical wave prediction method

Knowledge of the offshore wave climate is key to the design of coastal engineering structures and to the study of shoreline evolution. To date, the available wave data have been limited both in time and space; even though there are several options for obtaining wave data calculated using complex numerical models at basin scale, design issues can in some cases be solved by means of simpler models. This paper shows whether, under certain conditions and in an enclosed basin, an old empirical model can provide results that are good enough to determine the design condition necessary for engineering purposes. The empirical model chosen to answer this question is called Sverdrup–Munk–Bretschneide…

Tsunami Vulnerability Evaluation for a Small Ancient Village on Eastern Sicily Coast

The Ionian sea is prone to tsunamis due to its proximity to the Calabrian subduction zone, which is one of the major tsunamigenic areas of the Mediterranean. The tsunami disaster risk is, nowadays, significantly higher due to the increased exposure of buildings as a result of the economic and touristic growth of the Mediterranean coastal areas. This study focuses on Marzamemi, a small village in the western coast of Sicily, since its morphology and human presence amplify the need to assess its buildings’ vulnerability. The main objective of this research is to quantify the building vulnerability to tsunami hazards using a physical and realistic tsunami scenario. For this purpose, the relati…

Confronto fra valutazioni del run-up fatte con un modello matematico e una formula empirica con misure di campo

La posizione planimetrica della linea di riva, soli tamente, viene determinata attraverso l’uso di immagini aeree ed utilizzata pe r la ricostruzione dell’evoluzione storica dei litorali. Tuttavia, le informazioni est ratte da tali immagini, descrivendo il confine istantaneo acqua-terra, consentono l’indivi duazione della linea di riva esclusivamente come limite asciutto-bagnato proprio nel momento della ripresa. Per una più corretta localizzazione della linea di riva , è quindi necessario quantificare, oltre agli effetti di marea e di trasporto solido, gli effetti prodotti dal moto ondoso su tale posizione e in particolare il cosiddetto ru n-up. Nel presente lavoro si studia il run-up in u…

Trend dei deflussi in Sicilia

Gli effetti del cambiamento climatico si manifestano in maniera apprezzabile nelle modifiche subite da precipitazioni, temperatura e deflussi, in numerose località del pianeta, non solo con riferimento alla loro entità, più frequentemente indagata, ma anche riguardo alla loro variabilità nel corso dell’anno. In riferimento a questo secondo aspetto, con il lavoro qui riportato, si è voluto indagare circa l’esistenza o meno di un trend nella durata delle stagioni e nella quantità di risorsa idrica prodotta durante le stagioni stesse. Queste in genere sono identificate con criteri legati alle cadenze mensili che tengono conto solo sommariamente dell’effettiva variazione climatica stagionale; p…

A new shoreline boundary condition for a highly nonlinear 1DH Boussinesq model for breaking waves

In order to model the wave motion and, in turn, the flow, within the nearshore region, in the last decades the derivation and the application of Boussinesq type of models have been extensively investigated. Nevertheless, in the framework of such depth integrated numerical models, the problems of modeling wave breaking and moving onshore boundary at the shoreline are not trivial and several approaches have been proposed to overcome these limits. In the present work an effort toward a more physical based model of the surf and the swash zone has been accomplished. In particular, starting from the work of Musumeci et al. (2005), a new model of the shoreline boundary condition has been implement…