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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-OWC were investigated. Hydrodynamic stationary simulations of a WEC array parallel to the coastline were carried out in order to choose the best devices for a non-stationary simulation. The devices selected for this simulation are Pelamis, Wave Dragon, Oyster 2, F–2HB, and Bref-HB. The non-stationary simulation was forced with thirty-nine years wave parameters reanalysis from ERA5 by ECMWF (European Centre for Medium-range Weather Forecasts). This simulation has allowed to obtain the capacity factor (CF) and the dissipative effects in the period from 1979 to 2018. Moreover, a preliminary cost-to-benefit analysis was carried out for the best performance WEC array only. Costs, revenues, LCoE (Levelized Cost of Energy), and payback period were therefore computed by means of economic assumptions. The high energy concentration near the coast produces hydrodynamic effects which have as a consequence potential erosion phenomena. A shoreline change analysis of three beaches of the studied coast was carried out. Such an analysis was focused on shoreline retreatment during the last thirty years. On the basis of the presented results, there is a slight economic advantage in installing a Wave Dragon scaled array with the added value of potentially giving beneficial effects on coastal erosion. Nevertheless, from a strictly economic point of view, other renewable resources could give better results (e.g. wind energy). The adopted methodology gives encouraging results that confirm the opportunity to deploy WEC devices in the Sicilian Channel together with devices exploiting other renewable resources.

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 tropicales, o son resultado de eventos con un gran período de retorno, como el impacto de tormentas y tsunamis muy energéticos, elevación del nivel del mar y variaciones en el suministro de sedimentos de los ríos. Para prevenir y reducir tales impactos, los gestores deben conocer la sensibilidad de los sectores costeros naturales, que está relacionada con la energía de las olas, las características/evolución de las playas y la tendencia del nivel del mar, así como la vulnerabilidad potencial y el valor económico de los sectores urbanizados.Este trabajo muestra la evolución costera y los impactos de las estructuras costeras y la caracterización y evolución de los sistemas dunares a lo largo de la costa mediterránea de Andalucía (España). Para ello, se definieron 47 unidades a lo largo de la costa de estudio, y se cuantificó la evolución de las tasas de evolución (erosión/acreción/estabilidad) para el período 1956-2016, mediante el uso de la extensión DSAS del software ArcGIS. Como resultado, 9 unidades registraron acreción, 19 erosión y 19 estabilidad y, en cuanto al balance de superficie de playa, 17 unidades presentaron balance positivo y 28 negativo con un balance neto de -29.738,4 m2/año. El análisis de la evolución costera evidenció el impacto de las estructuras sólidas: la acreción se observó principalmente aguas arriba de los puertos y espigones y en correspondencia con los rompeolas; la erosión se detectó aguas abajo de los puertos y espigones y en correspondencia con los malecones, revestimientos y deltas de los ríos más largos; la estabilidad se observó en las playas pequeñas y en las áreas costeras estabilizadas localmente por estructuras de protección y obras de sustento. Estos resultados se utilizaron para determinar la distribución de los sectores costeros alineados con la corriente y la deriva y la dirección principal del transporte de sedimentos.En cuanto a la caracterización y evolución de los sistemas dunares, se cartografiaron diferentes tipos de sistemas dunares, así como la posición y fragmentación de la punta de las dunas, y la ocupación y evolución humana desde 1977 hasta 2001 y desde 2001 hasta 2016. En total, se delimitaron 53 sistemas dunares. a lo largo de la costa mediterránea de Andalucía, diferenciando tres tipos: dunas embrionarias y móviles, dunas fijadas por herbáceas y dunas estabilizadas. Se observa un descenso generalizado de la superficie dunar en el periodo 1977-2001 (-7,5 x 106 m2), ligado al aumento de la ocupación antrópica (+2,3 x 106 m2), y fragmentación de las dunas, especialmente en las provincias de Málaga y Almería. Durante el período 2001-2016 se observaron cambios menores en el nivel de fragmentación y en la superficie de las dunas. Solo se observó un aumento de la superficie de dunas en playas estables o en acreción (4 de 53 sistemas de dunas), tanto en áreas naturales como antrópicas (generalmente aguas arriba de los puertos).

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 regarding the evaluation of tsunami forces on buildings and the studies carried out on the determination of structural capacity. Then, an advanced structural analysis software based on the Finite Element Method (FEM) is used to analyze the influence of parameters such as load type, masonry type and interaction properties type. Finally, an application on a typical two-storey masonry structure subjected to tsunami load according to the actual codes is presented and discussed, providing recommendations on the assumptions to be made for the definition of a reliable numerical model. The findings of the numerical simulations revealed that the structural response is strongly influenced by the modeling approach defined for the masonry walls in terms of interaction properties and the type of connection between orthogonal walls. Moreover, it was observed that, as for the case of seismic analysis, when local behavior governs the failure, lower structural capacity is obtained, while in the case of global behavior governing the failure, higher structural performances are provided.

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 Research), is made by vectorial polygons, corresponding to erosion or accretion areas obtained by the intersection between two coastlines. The dataset contains polygons related to the 1960-1994 and 1994-2012 periods.Once a common baseline was extracted from 2019 satellite images, 22 Physiographic Units (PU) were identified. The PU was defined based on geomorphologic criteria and by assuming a null net sediment budget (null sediment transport between two PU neighboring). Each coastal PU was connected to its contributing fluvial basins, also assigning the expected sediment delivery at the coastline.To perform the analysis, cross profiles along the coastline were generated and intersected with the polygons, calculating a response value, in terms of retreatment or accretion, to each of the cross-profile centroids. Finally, for each PU, the cumulated variations were computed.PUs with significant cumulative variations (more than 2 km) in at least one of the two epochs were identified and three different patterns were detected: accretion/retreatment, retreatment/accretion, and retreatment/retreatment. The response observed for the different PUs was then analyzed considering estimated sediment delivery, recognizing coherent (large sediment delivery = accretion) and incoherent (large sediment delivery = retreatment) behaviors, which have been interpreted as controlled by the history of soil/coastal erosion management practices.In particular, in spite of a very high expected sediment delivery, more than three-quarters of the Tyrrhenian coast resulted as affected by a marked retreat in 60-94 (same tens of meters) and a moderate accretion in 94-12, as the result of extensive coastal works which have been realized to mitigate coastal erosion.

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 relative vulnerability index of the buildings in Marzamemi was calculated by means of an improved Papathoma Tsunami Vulnerability Assessment (PTVA) model. The presented approach has three main improvements: (a) a probabilistic tsunami scenario was used; (b) a realistic signal of water surface linked with a specific focal mechanism was adopted; (c) a tsunami wave was propagated from offshore to nearshore using a nonlinear numerical model. The good results of the proposed methodology make it very useful for coastal risk planning conducted by decision makers and stakeholders.

The geodynamic context in which El Salvador is located, made of a convergent structure characterized by the interaction among six different plates, together with the lithological characteristics of the outcropping rocks and soils (mainly corresponding to deeply weathered acid pyroclastites, basic effusive rocks and volcanic ashes), are responsible for the very high seismically-induced landslide susceptibility of the country. These predisposing factors were decisive on the occurrence of thousands of seismically-induced landslides caused by two huge earthquakes on 13th January and 13th February 2001, which triggered thousands of landslides in the country. In particular, the February event (6.6M, onshore and intraplate at a depth of 10 km) triggered 5,371 landslides in an area of around 300km2. These gravitational phenomena took the form of debris slides, earth slides and debris flows and affected several inhabited areas damaging infrastructures and crops and causing, respectively 844 and 315 fatalities.Thanks to aerial photos taken soon after the days following both the two earthquakes and made available by the CNR (Centro Nacional de Registros - Instituto Geográfico y del Catastro Nacional), associated landslide maps have been prepared, where each phenomenon is represented by a landslide polygon and its LIP (Landslide Identification Point), located in the crown of the landslide. In particular, static landslide susceptibility models were prepared for the Ilopango (1594 landslides in an area of around 40km2) and the San Vicente (1602 landslides in an area of around 108 km2) sectors, by regressing the spatial distribution of the 13th February seismically-induced landslides on a set of explanatory variables obtained by a geologic map and a 10m pixel DTM (Digital Terrain Model). At the same time, shaking-dependent models were prepared by including also PGA (Peak Ground Acceleration) and the epicentral distance (ED) among the predictors.For both the two areas a marked increase of performance was observed (AUC from 0.70 to 0.75, for Ilopango, from 0.73 to 0.77, for San Vicente) from the static to the shaking-dependent models, highlighting the role of the seismic acceleration in the triggering of the landslides both in activating the susceptible sites and in lowering the score threshold for slope failures occurrences. Besides, for the Ilopango sector, a rainfall-induced susceptibility model was also prepared, exploiting a landslide inventory available for the 2009 IDA/12E storm events. The obtained score was then combined with PGA and ED to predict the spatial distribution of the seismically induced landslides, obtaining a higher performance than the relative basic model (AUC = 0.75).The results obtained from the research demonstrate suggest the possibility to couple the susceptibility scores obtained from static modelling to the expected mechanical shaking for the seismically-induced susceptibility assessment.The whole modelling was carried out by applying MARS (Multivariate Adaptive Regression Splines) analysis through RStudio and SAGA GIS freeware software.

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 necessary to study the links existing between coastal and marine morphological transformations. A new tool was written in Matlab, the input files were built using a GIS environment and the results were arranged in a GIS project. The present tool adopts two approaches: the Transect Based Analysis (TBA) and the Area Based Analysis (ABA). New roughness and irregularity indexes were defined to calculate the transects’ spacing. Moreover, a piecewise polynomial baseline was defined to improve accuracy in shoreline position assessment. The approaches TBA and ABA were validated both by synthetic benchmarks and by a study case. The adopted synthetic benchmarks represent very common types of beaches: with one or more salients, with cusps and groynes. The case study was a logarithmic spiral Mediterranean beach on the southwestern coast of Sicily. All the studied test cases provided good results in terms of accuracy and easiness of use. The new tool and methodology, with TBA and ABA coupling, encloses many practical aspects. Indeed, ABA allows the general assessment of advancing/retreating beach areas, whereas TBA is needed to study very short stretches of beach. The proposed SCA analysis is useful for the requirements of a complete coastal management plan and to evaluate erosion management options. Moreover, the SCA gives a sound technical understanding of the physical coastal processes and should engage the community, the stakeholders and the agencies responsible for development application decisions. The new approach gives high-quality results achieved with significant speediness making it suitable for regional studies and directly providing parameters needed for erosion managing strategies

Coastal areas are among the most biologically productive, dynamic and valued ecosystems on Earth. They are subject to changes that greatly vary in scale, time and duration and to additional pressures resulting from anthropogenic activities. The aim of this work was to investigate the shoreline evolution and the main environmental changes of the coastal stretch between the towns of Licata and Gela (in the Gulf of Gela, Sicily, Italy). The methodology used in this work included the analysis of: (i) shoreline changes over the long- and medium-term periods (1955–2019 and 1989–2019, respectively), (ii) dune system fragmentation and (iii) the impact of coastal structures (harbours and breakwaters) on coastal evolution. The shoreline change analysis mainly showed a negative trend both over the long- and medium-term periods, with a maximum retreat of 3.87 m/year detected over the medium-term period down-drift of the Licata harbour. However, a few kilometres eastward from the harbour, significant accretion was registered where a set of breakwaters was emplaced. The Shoreline Change Envelope (SCE) showed that the main depositional phenomena occurred during the decade between 1955 and 1966, whereas progressive and constant erosion was observed between 1966 and 1989 in response to the increasing coastal armouring.

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This paper shows coastal evolution along the Andalusia Region (Spain) and the impacts on it of coastal structures. The study area was divided into 47 units to calculate the erosion/accretion/stability (or evolution) rates by using the DSAS extension of ArcGIS software. Evolution rates were divided into different classes from &ldquo, Very high accretion&rdquo, to &ldquo, Very high erosion&rdquo, As a result, 9 units recorded accretion, 19 stability and 19 erosion. Further, 17 units presented a positive balance and 28 units a negative one, showing a negative net balance of 29,738.4 m2/year corresponding to the loss of 1784.30 km2 of beach surface in the 1956&ndash, 2016 period. The distribution of evolution areas along the studied coast was carried out by means of the &ldquo, R&rdquo, project for statistical computing. The analysis evidenced the impact of rigid structures: accretion was essentially observed up-drift of ports and groins and in correspondence of protection structures, especially of breakwaters. Erosion classes were observed down-drift of ports and groins and in correspondence of revetments/seawalls, and at largest river deltas, and &ldquo, stability&rdquo, was observed at pocket beaches and coastal areas locally stabilized by protection structures. Last, results were used to determine the distribution of swash- and drift-aligned coastal sectors and main direction of sedimentary transport.

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 prototype manufacturers and it allows to compute the energy flux that can be extracted, depending on the significant wave height and on the peak period. Wave climate has been obtained from the Mazara del Vallo wave buoy dataset, covering the years from 1995 to 2005. The numerical model analysis results include the comparison between the energy flux distribution both in the case of presence of WECs and in their absence. The results obtained through the nearshore analysis allowed to assess the devices efficiency. Among the simulated devices only the Oyster 2 had a high value efficiency whereas for the other two devices lower power values were obtained. This results because the prototypes were designed considering the ocean wave conditions, which are of an order of magnitude higher than the conditions that occur in a closed sea basin, as is the Mediterranean Sea.

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, impacts, and human occupation and evolution from 1977 to 2001 and from 2001 to 2016. Within a GIS (Geographic Information System) project, 53 dune systems were mapped that summed a total length of ca. 106 km in 1977, differentiating three dune environments: (i) Embryo and mobile dunes (Type I), (ii) grass-fixed dunes (Type II) and (iii) stabilized dunes (Type III). A general decrease in dunes&rsquo, surfaces was recorded in the 1977&ndash, 2001 period (&minus, 7.5 &times, 106 m2), especially in M&aacute, laga and Almer&iacute, a provinces, and linked to dunes&rsquo, fragmentation and the increase of anthropic occupation (+2.3 &times, 106 m2). During the 2001&ndash, 2016 period, smaller changes in the level of fragmentation and in dunes&rsquo, surfaces were observed. An increase of dunes&rsquo, surfaces was only observed on stable or accreting beaches, both in natural and anthropic areas (usually updrift of ports).

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 inundation. Ionic coast of Sicily (Italy) was chosen as a case study due to its high level of exposure to tsunamis. Indeed, the tsunami could be generated by an earthquake in the external Calabrian arc or in the Hellenic arc, both active seismic zones. Finally, in order to demonstrate the possibility to give indications to local authorities, an inundation map, over a small area, was produced by means of the numerical model.

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 obtained through the development of the nearshore analysis detected four energetic hotspots close to the coast of the islands. Near Marettimo island, only one hotspot was detected with a maximum wave energy flux of 9 kW/m, whereas, around Favignana, three hotspots were identified with a maximum wave energy flux of 6.5 kW/m. Such values of available wave energy resource are promising to develop different projects for wave energy converters in specific areas along the coast, in order to improve the energetic independence of Aegadian islands.

This paper investigates wave climate and storm characteristics along the Mediterranean coast of Andalusia, for the period 1979&ndash, 2014, by means of the analysis of wave data on four prediction points obtained from the European Centre for Medium-Range Weather Forecasts (ECMWF). Normally, to characterize storms, researchers use the so-called &ldquo, power index&rdquo, In this paper, a different approach was adopted based on the assessment of the wave energy flux of each storm, using a robust definition of sea storm. During the investigated period, a total of 2961 storm events were recorded. They were classified by means of their associated energy flux into five classes, from low- (Class I) to high-energetic (Class V). Each point showed a different behavior in terms of energy, number, and duration of storms. Nine stormy years, i.e., years with a high cumulative energy, were recorded in 1980, 1983, 1990, 1992, 1995, 2001, 2008, 2010, and 2013.

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, no action&rdquo, to the &ldquo, protection&rdquo, option, coastal managers need to know the intrinsic coastal sensitivity and the potential vulnerability and value of land uses. In this paper, in a first step, coastal sensitivity was determined by calculating the following: (i) the spatial distribution at the coast of the wave forcing obtained by using the ERA5 wave dataset and defined as the energy associated with the 50-year return period storm. Two storm conditions were considered, that is, one for the eastern and one for the western parts of the Andalusia Mediterranean coast, respectively, characterized by a height of 8.64&ndash, 7.86 m and 4.85&ndash, 4.68 m and (ii) the existence of a buffer zone, namely the dry beach width expressed as a multiple of the 20-year predicted shoreline position that was calculated using a dataset of aerial photographs covering a time span from 1956 to 2016. Coastal sensitivity values were divided into five classes with class 1 indicating the lowest sensitivity (i.e., the presence of a wide buffer zone associated with low wave energy flux values) and class 5 the highest sensitivity (i.e., a narrow buffer zone associated with very high wave energy flux values). In a second step, land uses were obtained from the official Land Use Map of the Andalusia Region, based on the results of the &ldquo, Coordination of Information on the Environment&rdquo, (CORINE) European Project. Such uses were divided into five classes from class 1 including natural areas (typologies &ldquo, A&rdquo, and &ldquo, B&rdquo, of the CORINE Project) to class 5 including very capital land uses (typologies &ldquo, E1&rdquo, E2&rdquo, ). In a third step, information concerning coastal sensitivity and land uses was crossed to determine the best mitigation strategies to cope with erosion processes. The &ldquo, option was observed at the westernmost area of C&aacute, diz Province and at some areas from the west coast of Almer&iacute, a Province, where both coastal sensitivity and land use classes show low values, the &ldquo, adaptation&rdquo, option was recorded along more than one half of the coast studied, essentially at natural areas with high sensitivity and at urbanized areas with low sensitivity, and the &ldquo, option was observed especially at some areas from the center and eastern part of M&aacute, laga Province and at the easternmost areas of Almer&iacute, a Province, where both coastal sensitivity and land use classes presented high values.

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 wave run-up uncertainty, we used a spectral numerical model to propagate waves from deep to intermediate water and a Boussinesq-type model for intermediate water up to the swash zone. Tide effects on the uncertainty of shoreline position were evaluated using data collected by a near tide gauge. The proposed methodology was applied to an unprotected, dissipative Sicilian beach far from harbours and subjected to intense human activities over the last 20 years. The results show wave run-up and tide errors ranging from 0.12 m to 4.5 m and from 1.20 m to 1.39 m, respectively.

Emplacement of hard coastal defence structures, such as seawalls, revetments, groins and breakwaters, or even ports, harbours and marinas, is commonly known as coastline armouring. This paper deals with coastal armouring evolution along the 546 km Mediterranean coast of Andalusia (Spain). It is based on photo interpretation and GIS tools, which have been employed to map coastal structure emplacement and evolution by analysis of 1956, 1977, 2001 and 2010 aerial photos. Additionally the coefficient of infrastructural impact K , which represented the relation between the total length of maritime structures and the length of the study coastal section, was obtained - i.e. minimal at 0.001 ≤ K average when 0.1 ≤ K maximal at 0.5 ≤ K extreme , when K ≥ 1.0. In the mid 50s, coastal zones presented a very low level of armouring and the most important settlements were coastal towns and associated fishing communities. The total length of anthropogenic structures, 11 ports and a few protection structures, gave rise to K values ranging from “minimum” (with average K = 0.07) to K “extreme” ( K = 2.5 in 8 sectors). During the 60s and 70s, the armoured coastline length increased from 42.1 (1956) to 98.2 km (in 1977). The “minimum” K value maintained the same average value (0.07) but affected 10 sectors. The “extreme” K value increased the average value to 3.6 and affected 25 sectors. The above was essentially linked to coastal tourism development under an extreme laissez-faire politico-economic regime: several ports were enlarged and new marinas constructed specially along the Costa del Sol. Induced coastal retreat processes were counteracted by progressive groin emplacement to enlarge tourist beaches and/or halt coastal erosion: 42 groins and 1 breakwater in 1977, some 8 fold increase with respect to 1956. Revetments and seawalls occupied a total amount of 7.6 km. Coastal occupation modalities from the mid 70s to 2001 were similar to the previous period. The armoured coastline length increased from 98.2 to 182.3 km, with “minimum” K values (average: 0.09) recorded in 15 sectors and “extreme” values (average K = 4.7) recorded in 33 sectors. Coastal occupation and tourism development did not record significant improvements during 2001–2010 and K values recorded a small increase. Approaches used to halt beach erosion were coastal structures as coastal tourism was the main beach management target, carried out essentially by increasing beach carrying capacity without consideration of ecological and environmental aspects. In the last few decades, coastal defence policies experienced important changes based on reshaping/removal of hard structures and the realization of nourishment.

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 events such as sea storms, earthquakes and tsunamis. The research examines the uncertainty in positioning the shoreline coupling remotely sensed images and a hydro-maritime model. Although the assessment accuracy strongly relies on data availability and consistency, the resulting assessment of the shoreline erosion and accretion is crucial for an overall understanding of the hydro-maritime geo-morphological interaction. The study case is the Marsala coastline (western coast of Sicily, Italy), named 12th island physiographic unit. It is characterized by a low coast with sandy sediments from Holocene age. These sediments are in continuity of sedimentation on whitish debris composed by organogenic limestone from Pleistocene age. The diachronic analysis was carried out on both emerged and submerged parts of the beach and involves two distinct phases. In the first phase, geo-morphological in situ data have been compared with maps and georeferenced remote sensing images referred to the period 1994-2006. It allowed the identification of shoreline indicators [2] such as the beach cross-section and the shoreline positioning including its spatial and temporal variations. It should be noted that the comparison between EO (Earth Observation) images and cartographic maps is subjected to several uncertainties, due to graphic error, geo-referencing accuracy and spatial resolution. Moreover tidal and climate waves data refer to an acquisition time different to that of the EO images. In the second phase, a maritime hydraulic modelling accounting for sea fluctuations has been performed. The run-up is related to wave's amplitude and phase, as well as to the composition and particle size of the beach sediments determining the beach slope [3]. Prior to run-up calculation, an investigation aiming to evaluate how the waves propagate from offshore to inshore (a third-generation spectral wave numerical model, SWAN - Simulating WAves Nearshore), has been carried out. Wave data have been acquired by a buoy belonging to the National Network Waves Data, located at the SW of the Mazara del Vallo harbour (Trapani), while tide data were recorded by the national marigraph of Porto Empedocle (Agrigento). The results allowed assessing the uncertainty and the consequent accuracy in the shoreline positioning for given slope, highlighting that it is not always possible to assess the shoreline rise and fall, for values lower than 10-15 m.

Karst areas are distributed over most of Sicily. The most widespread karst rocks are carbonates, particularly limestones, but karst phenomena can also be seen in evaporites and particularly in salt mines. This report provides an overview of evaporite karst in Sicily, along with a “case history” that shows some of the evaporite karst risks to the environment. In the centre and south of Sicily, a thick sequence of Messinian evaporite rocks are subject to dissolution from meteoric and formation waters. In areas where potassium salts and rock salts are being mined, some geomorphologic changes result from the drilling of boreholes and the collapse of underground mines, thus lowering or collapsing the land surface. An example is the old salt mine “Muti-Coffari”, situated in the commune of Cammarata, where there is a modification of the surface flow of the River Platani. Meteoric waters and runoff flow down through a borehole, enter the underground mine cavity and dissolve the salts, and then the resulting brine flows into a branch of the river, making it salty. Field investigations showed the presence of salt along the edges and on the bed of the stream where it comes out of the cave. Therefore, interventions for risk mitigation are necessary since the old mine constitutes a serious danger for damage or collapse of nearby infrastructures, and can lead to degradation of the river ecosystem and the natural environment.

The River Platani, situated in the western side of Sicily, is one of the greatest rivers of the island. It runs for about 103 Km and the basin extends to about 1,784.9 Km. It rises near Santo Stefano Quisquina (Ag); the river flows to Capo Bianco (Ag) ends in the Mediterranean Sea. The morphology of the basin is predominantly characterized by rises of modest entities with slopes sweet or calanques. In the containing gypsum and carbonatic stony heaps are diffused the karst phenomena. In the Platani basin some mines are located of rock salt and potassium salts; today the mines are closed after a long activity and they interact with the geomorphology of the territory and on the water quality of the river. An example is given by the ex mine “Muti-Coffari” (Ag), in fact the mine determines an evident incidence on the physical-chemical characteristics of the water and the fluvial ecosystem. Where the “sinkholes” are present, caused by the incessant thinning of the vault and pillars of the mine’s tunnel, meteoric water penetrates inside, flooding all the underground levels; the waters, through different chemical process, attach the evaporitics rocks and they have a concentration of salts. Consequently, because of the flooding of the tunnels, the saturated salt waters escape from the entrance of the mines to flow into the River Plantain. Through the monitoring of the principal branch of the River Platani it can be deduced that the river can be considered constituted by two separate ecosysystems: the first goes from the source to the point of immission of the small affluent coming from the mine; the second extended from the salt mine up to the mouth. Observing the graphs products on the chemical-physical parameters evident as the element of separation is constituted by the immission of saturated salt water. After the immission of the Torrente Salina, the values of the sulphates, of the chlorides, and of the sodium, sensitively increase. The environmental aspect that derives is a hyper saltiness that affects the fluvial ecosystem, as a matter of fact a desertification of fertile areas where once there were very fertile cultivations.

Given the increasing phenomenon of Sinkholes all over Italy, the Gruppo Nazionale per la Difesa dalle Catastrofi Idrogeologiche (G.N.D.C.I) and the Dipartimento della Protezione Civile (D.P.C.), during 2004, started a plan called Sinkholes dedicated to the phenomena in Italy. The plan provides the publication of the database realized by the D.P.C. by means of the census of beyond 1000 cases scattered across the nation. The city of Marsala is strongly characterized by the presence of a great number of Calcarenite cavities. The material object of extraction is the Calcarenite di Marsala of the Pleistocene, frequently used in the construction of buildings. The presence of the underground cavities in the city subsoil has in the last few decades caused a series of landslides whose frequency has visibly increased. The sinkholes have affected buildings and infrastructures. In the case of the evaluation of the hazard following the collapse of an underground cavity it is not possible to do probabilistic evaluations on the occurring events in a definite period. Such difficulty can be overcome if the concept of hazard is replaced with that of danger where no probabilistic term is included. In this context a methodology for the evaluation of the risk of Sinkholes proposes to foresee the identification of hazard expose areas and estimates the hazard H factor and potential damage D factor. Every factor will be given a weight, chosen inside of established classes of value. Through combination of the two factors, hazard H and potential damage D, risk will be determined. The risk areas will be subdivided into zones with different degrees of exposure to the danger. In order to visualize and to localize the areas of interest by cavity and those already subject to landslides, a database has been realized, coordinated with a program GIS. Relatively to the areas subject to landslides, where possible, photographs, planimetries have been inserted and, in addition, a list has been compiled purposely proposed by the G.N.D.C.I and by the D.P.C. Risk Analysis V: Simulation and Hazard Mitigation 107 www.witpress.com, ISSN 1743-3541 (on-line) © 2006 WIT Press WIT Transactions on Ecology and the Environment, Vol 91, doi:10.2495/RISK060111 Sinkholes risk analysis: case history of Marsala (Sicily, Italy)

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 Lagrangian shoreline model. In such simulations monochromatic waves have been propagated in a numerical flume having the same beach slope of the measured transect. The comparison between registered and estimated run-up have underlined an acceptable agreement. In particular, it has been obtained that the numerical model tends to underestimate the run-up, instead the applied empirical formula gives overestimated values.