Giovanni De Falco

Management of Beach-Cast Posidonia oceanica Seagrass on the Island of Sardinia (Italy, Western Mediterranean)

Abstract Removal of beach-cast Posidonia oceanica seagrass litter, called “banquettes,” is a common practice on Mediterranean shores to allow the recreational use of beaches. Ongoing removal practices of P. oceanica banquettes were analyzed on the island of Sardinia to quantify this phenomenon on a broad scale and to evaluate the potential environmental impacts of banquette removal and dumping on the coastal zone. Data on banquette management were collected by means of a questionnaire given to the coastal municipalities and private companies in charge of beach-cleaning operations during 2004. P. oceanica banquette removal resulted in a widespread practice applied on 44 beaches (out of 116). The total removed amount for 2004 was estimated at 106,180 m3. Heavy machines were generally used to remove banquettes. Relationships between banquette removal and beach characteristics showed that higher quantities removed resulted in low-energy beaches. The amount of sediment subtracted to the beach following removal was evaluated by analyzing sand concentration in banquettes collected at three locations. Mean sediment concentration in banquettes was 92.8 kg m−3. This value, multiplied for the amount of banquettes removed, allowed us to evaluate the sediment subtracted from each beach between 0.5 and 1725 m3. Furthermore, the majority (80%) of the volume removed was dumped in unauthorized areas. Following the findings of the study, some management measures are suggested in order to minimize environmental impact of banquette removal.

STREAM-SCANNING LASER SYSTEM, ELECTRIC SENSING COUNTER AND SETTLING GRAIN SIZE ANALYSIS: A COMPARISON USING REFERENCE MATERIALS AND MARINE SEDIMENTS

Abstract Surface and deep-sea core sediments and two sets of standards were measured by three different techniques — Galai Cis-1 laser system, Coulter Counter TA II, and Micromeritics SediGraph 5000D — in order to compare the Galai results with the other two. The differences between the three types of measuring device turned out to be greater in sediments than in standards, and were attributed to the physical properties, shape, density and composition of the particles (complexity of the matrix). Comparison of moment statistics showed that the Galai determines coarser grain sizes than the Coulter and finer than the SediGraph, particularly as regards analysis of surface sediments. The relationships between Galai and SediGraph were estimated using analysis of variation/residuals within individual intervals. The analysis showed a higher variability of residuals for the coarser fractions (8–16 μm and 16–32 μm) with respect to the finer (2–4 μm and 4–8 μm) fractions. The

Sediment Analysis Evidences Two Different Depositional Phenomena Influencing Seagrass Distribution in the Gulf of Oristano (Sardinia, Western Mediterranean)

Abstract Sediment grain size and total organic carbon (TOC) content in sediments, coupled with image processing analysis, were investigated to assess natural vs. anthropogenic distribution patterns of Posidonia oceanica seagrass meadow, in the proximity of a river mouth and a port embankment in the Gulf of Oristano (Sardinia, Italy). Two unvegetated areas (∼9 km2 each) were detected by meadow mapping: (i) in front of the river mouth, and (ii) close to the port. Both unvegetated areas were characterised by a high silt+clay content in the bottom sediments, allowing us to identify the deposition of fine sediments as a factor limiting P. oceanica distribution. A marked variation within the depth of sediment grain size was recorded close to the port, where a 5-cm layer with silt+clay >50% overlapped a sediment with silt+clay <20%, suggesting a recent change in depositional processes. Grain-size fractionation was analysed using the silt : clay ratio, which indicated high-energy conditions in the area close to the port. Differently high TOC concentrations were found in front of the river mouth. These data allowed us to identify two different types of sedimentary process impacts on P. oceanica distribution: (i) a “natural” limitation because of the river inflow and (ii) an anthropogenic impact due to fine-sediment deposition following the dredging and building of the port.

Morphological changes of a Mediterranean beach over one year (San Giovanni Sinis, western Mediterranean)

ABSTRACT Simeone, S., De Falco, G., Quattrocchi, G., Cucco, A. 2014. Morphological changes of an Mediterranean beach over one year (San Giovanni Sinis, western Mediterranean).In: Green, A.N. and Cooper, J.A.G. (eds.), Proceedings 13th International Coastal Symposium (Durban, South Africa), Journal of Coastal Research, Special Issue No. 70, pp. 217–222, ISSN 0749-0208. Mediterranean beaches experience major modifications in their morphology and grain size features mainly during intense storms and extreme meteo-marine events. The assessment of beach response to storms can be useful in the evaluation of coastal hazards, and in relation to the efficiency of management projects such as artificial nourishment. This paper aims to establish the subaerial morphological response of a beach located in western Sardinia (western Mediterranean) during the period of a year. Both experimental and numerical approaches were adopted to investigate the beach system. In particular, beach profiles, acquired by means of Differential Positioning System were used to analyze the morphological changes of the beach and wave parameters and current velocity data were collected by means of an Acoustic wave and current meter (ADCP). Numerical techniques were also applied to investigate the hydrodynamics in the area of study. Coupled wind wave - 3D hydrodynamic finite element model were used to reproduce the wave propagation and the wind, tide and wave induced 3D water circulation along the coastal areas, and it displayed a good accuracy. During the year, the beach experienced intense morphological changes in the area where submerged beach is not occupied by rocky outcrops and the model was also able to reproduce the related observed periods of strong wind wave events. The interdisciplinary approach allowed an evaluation to be made about the response of the beach morphology in respect to meteo-marine forcings.

Sandy beaches characterization and management of coastal erosion on western Sardinia island (Mediterranean Sea).

ABSTRACT De Falco, G., Budillon, F., Conforti A., De Muro, S., Di Martino G., Innangi, S., Perilli, A., Tonielli, R., Simeone, S. 2014. Sandy beaches characterization and management of coastal erosion on western Sardinia island (Mediterranean sea).In: Green, A.N. and Cooper, J.A.G. (eds.), Proceedings 13th International Coastal Symposium (Durban, South Africa),Journal of Coastal Research, Special Issue No. 70, pp. 395–400, ISSN 0749-0208. Coastal erosion is a global problem which affects sandy and rocky shores worldwide. Coastal erosion can be triggered by several causes. Local processes can generate erosion hot spots, whereas at the global scale, the main forces are sea level rise, changes in storm climate and human interference. Beaches along the Mediterranean sea are strongly affected by coastal erosion. Recently, the Protocol on Integrated Coastal Zone Management in the Mediterranean (PAP/RAC 2007) recommended the prevention of erosion processes by restoring the natural adaptive capacity of the coast and by improving the knowledge on the state, development and impact of coastal erosion. In order to achieve the objective of the PAP/RAC protocol, we characterized 24 sandy beaches along ~270 km of the western coastline of the Sardinia island (western Mediterranean). Grain size and mineralogy of the foreshore sediments were analyzed and the intertidal elevation/bathymetric profile were measured using the Differential Global Positioning System. Aerial photos were used to identify the shoreline configuration, the number of bars and morphodynamic features. A digital elevation model (DEM) of the adjacent shelf was produced and acoustic backscatter, grab and box-corer sediment samples were collected in order to characterize the seafloor and to identify the substrate lithology, particularly the distribution of sandy sediments. The investigated coastline is characterized by linear, multibarred beaches and wide transgressive dune fields formed by terrigenous and coarse sand. These linear beaches are alternated with embayed beaches which locally show a mixed terrigenous/bioclastic carbonate composition. Large sandy bodies were found in the inner shelf, often forming dune fields which were uncovered by mud drapes. A database was created to facilitate the characterization of the beach systems along the studied coastline and adjacent inner shelf. It is anticipated that the database will be used by policy makers in support of the implementation of coastal erosion management strategies.

Morphodynamics of a Nontidal Embayed Beach: The Case Study of Is Arutas (Western Mediterranean)

ABSTRACT Simeone, S.; Palombo, L., and De Falco, G., 2013. Morphodynamics of a nontidal embayed beach: the case study of Is Arutas (western Mediterranean). This study evaluates the reliability of the Short morphodynamic model by using experimental data on the wave climate, sediment budget, and topographic beach profiles of an embayed beach located in western Sardinia, Mediterranean Sea. Wave parameters, measured by an offshore buoy located to the NW of Sardinia were downloaded daily, from the Rete Ondamentrica Nazionale Web site. Beach elevation data were collected in 2005 and 2010, using a Differential Global Positioning System, to determine the volume of beach sediments. Three beach profiles were measured in the northern, central, and southern areas of the beach from September 2010 to May 2011 to investigate morphological variability. Grain-size and composition of beach sediments were determined. From 2005 to 2010, the sediment volume did not show any significant changes (14,200 m3 and 13,800 m3, respectively). Sediments were sandy to gravelly, whereas the composition was siliciclastic. Morphological variability occurred in the swash zone, where the northern and southern profiles showed an opposite trend, in terms of changes in elevation. This was related to the longshore redistribution of sediments and occurred mainly during the autumn–winter season. The Short model revealed that, for 98% of the available data, Is Arutas assumed a “normal” or “transitional” morphodynamic state. The sediment remained constrained between the headlands, in accordance with the results of the Short model, which showed the assumed morphodynamic states did not implicate the transport of sediment outside the system. Experimental data confirmed that the Short morphodynamic model can be applied to studies on sediment exchange on embayed Mediterranean beaches.

Biogenic sediments from coastal ecosystems to Beach-Dune Systems: implications for the adaptation of mixed and carbonate beaches to future sea level rise

Coastal ecosystems produce and store carbonate particles, which play a significant role in the carbonate dynamics of coastal areas and may contribute to the sediment budget of adjacent beaches. In the nearshore seabed of temperate zones 10 (e.g. Mediterranean Sea and South Australia), marine biogenic carbonates are mainly produced inside seagrass meadows. This study quantifies the contribution of biogenic sediments, mainly produced in Posidonia oceanica seagrass meadows and secondarily in photophilic algal communities, to the sediment budget of a Mediterranean beach-dune system (San Giovanni beach, western Sardinia, western Mediterranean Sea). A set of geophysical, petrographic and sedimentological data were used to estimate the sediment volume and composition of the beach-dune system as a whole. The San Giovanni beach-dune 15 system contains 3,797,000±404,000 tons of sediments, 83% (3,137,000±404,000 tons) of which are located in the coastal wedge, 16% (619,000±88,000 tons) in the dune fields and 1% (41,000±15,000 tons) in the subaerial beach. The sediments are composed of mixed modern bioclastic and relict bioclastic and non-bioclastic grains from various sources. The system receives a large input of modern bioclastic grains, mainly composed of Rhodophytes, Molluscs and Bryozoans, which derive from sediment production by present-day carbonate factories, particularly P. oceanica seagrass meadows. Radiocarbon 20 dating of modern bioclastic grains indicated that they were produced during the last 4.37 ka. This value was used to estimate the long-term deposition rates of modern bioclastic sediments in the various beach compartments. The total deposition rate of modern bioclastic grains is 46,000±5,000 tons century, mainly deposited in the coastal wedge (39,000±4,000 tons century) and dunes (7,000±1,000 tons century), and 46,000 tons represents ~ 1.2% of the total beach-dune sediment mass. Carbonate production from coastal ecosystems was estimated to be 132,000÷307,000 tons century, 28% (15%÷34%) of 25 which is transported to the beach-dune system, thus significantly contributing to the beach sediment budged. The contribution to the beach sediment budget represents a further ecosystem service provided by P. oceanica, which our data can help quantify. The value of this sediment-supply service is in addition to the other important ecological services provided by seagrass meadows. The dependence of the beach sediment budget on carbonate production associated with coastal ecosystems has several implications for the adaptation of mixed and carbonate beaches to the loss of seagrass 30

Flooding scenario for four Italian coastal plains using three relative sea level rise models

ABSTRACT The coastal areas of the central Mediterranean Sea are sensitive to climate change and the consequent relative sea level rise. Both phenomena may affect densely urbanized and populated areas, causing severe damages. Our maps show the land-marine flooding projections as effects of the expected relative sea level rise for four Italian coastal plains using (i) IPCC AR5 estimations, based on the IPCC RCP 8.5 emission scenarios and (ii) the Rahmstorf 2007 model. Isostatic and tectonic data were added to the global projections to estimate the relative sea changes expected along the coastline by 2100, as well as sea-flooding. The northern Adriatic map shows the study area, extending for about 5500 km2, and is presented at a scale of 1:300,000 with two inset maps at a scale of 1:150,000. The Oristano coastal plain is about 125 km2; the map scale is at 1:60,000 with an inset map scale at 1:33,000. The Cagliari coastal study area extends for 61 km2; the map scale is at 1:60,000 with two inset maps at 1:30,000. The Taranto area extends for 4.2 km2 and is represented at a scale map of 1:30,000, while the three inset maps are at a scale of 1:10,000.

Beaches Morphological Variability Along a Complex Coastline (Sinis Peninsula, western Mediterranean Sea).

ABSTRACT Simeone, S., De Falco, G., Quattrocchi, G., Palombo, L., Cucco, A. 2016. Beaches morphological variability along a complex coastline (Sinis Peninsula, western Mediterranean Sea). In: Vila-Concejo, A.; Bruce, E.; Kennedy, D.M., and McCarroll, R.J. (eds.), Proceedings of the 14th International Coastal Symposium (Sydney, Australia). Journal of Coastal Research, Special Issue, No. 75, pp. 1302 - 1306. Coconut Creek (Florida), ISSN 0749-0208. Wave climate, sediments, topographic features and tides influence the morphology and the short-term dynamics of beaches. The interactions between these different forcings affect the features of the beach system. In this work the morphological beach responses in relation to the most energetic period of the year were studied in a coastline with high geomorphological complexity. Three beaches, located along the Sinis Peninsula (western Mediterranean Sea, western Sardinia), were monitored for about 6 months. In order to estimate morphological changes, repetitive beach profiles were acquired by means of Differential Global Positioning System. Wave data were collected by an offshore wave buoy and the grainsize features of each beach was determined. A coupled 3D hydrodynamics–wave, finite element model was also applied in order to investigate the current dynamics and the wave propagation along the selected coastal area. During the monitoring period, the beaches experienced relevant changes when consecutive storms occurred. In sediment deprived embayed beaches, the presence of headlands interacting with waves, favored beach rotation and lead to a crenulate shape of the shoreline. In addition, on sediment abundant beach, cross-shore sediment transport and simultaneous shoreline retreats were observed during storms events. Finally, the effects on the wave heights and directions, due complex coastline features of the Sinis Peninsula, were discussed in relation to the morphodynamics response of each beach.

Sorted Bedforms Along the Continental Shelf of Western Sardinia

Two sorted bedforms fields located at the western Sardinian margin are described. Bedforms are developed at the edge of prograding sedimentary wedges related to the last sea-level rise and in a small basin of the inner shelf, surrounded by rocky outcrops. The mechanisms of formation and evolution are discussed in relation with sea-level oscillations, hydrodynamic forcing and complex seabed morphology.