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In this work, we investigated if the Eulerian and the Lagrangian approaches for the computation of the Transport Time Scales (TTS) of semi-enclosed water bodies can be used univocally to define the spatial variability of basin flushing features. The Eulerian and Lagrangian TTS were computed for both simplified test cases and a realistic domain: the Venice Lagoon. The results confirmed the two approaches cannot be adopted univocally and that the spatial variability of the water renewal capacity can be investigated only through the computation of both the TTS. A specific analysis, based on the computation of a so-called Trapping Index, was then suggested to integrate the information provided by the two different approaches. The obtained results proved the Trapping Index to be useful to avoid any misleading interpretation due to the evaluation of the basin renewal features just from an Eulerian only or from a Lagrangian only perspective. [ABSTRACT FROM AUTHOR]

This work gives an assessment of the hazard faced by Sicily coasts regarding potential offshore surface oil spill events and provides a risk assessment for Sites of Community Importance (SCI) and Special Protection Areas (SPA). A lagrangian module, coupled with a high resolution finite element three dimensional hydrodynamic model, was used to track the ensemble of a large number of surface trajectories followed by particles released over 6 selected areas located inside the Sicily Channel. The analysis was carried out under multiple scenarios of meteorological conditions. Oil evaporation, oil weathering, and shore stranding are also considered. Seasonal hazard maps for different stranding times and seasonal risk maps were then produced for the whole Sicilian coastline. The results highlight that depending on the meteo-marine conditions, particles can reach different areas of the Sicily coast, including its northern side, and illustrate how impacts can be greatly reduced through prompt implementation of mitigation strategies. [ABSTRACT FROM AUTHOR]

Abstract: Measures of transport scale in aquatic systems can contribute to the formulation of definitions of indicators of the system’s ecological properties. This paper addresses confinement, a specific transport scale proposed by biological scientists as a parameter that can capture and synthesize the principal properties that determine the spatial structure of biological communities in transitional environments. Currently, there is no direct experimental measure of confinement. In this study, a methodology based on the accumulation rate within a lagoon of a passive tracer of marine origin is proposed, the influences of different factors in the calculation of confinement are analyzed, and general recommendations are derived. In particular, we analyze the spatial and the temporal variability of confinement and its sensitivity to the seasonal variability of climatic forcing, the inputs from rivers and the parameterization of the tidal exchanges. The Lagoon of Venice is used as a case study. [Copyright &y& Elsevier]

Abstract: Oil spill is a serious threat for all marine and coastal environments. This is even more true for areas having high environmental, social and/or touristic value. A serious and scientifically rigorous identification of the hazard and risk related to oil slicks is becoming mandatory, in order to reduce or mitigate the impact of oil dispersal at sea and its stranding. A new model based method for evaluating hazard of oil slicks contact with shorelines of the Archipelago of La Maddalena (Strait of Bonifacio, Sardinia, Italy) has been developed and applied. The core of the methodology is a coastal 3D finite elements model, able to simulate hydrodynamics and waves of the strait of Bonifacio and, through a Lagrangian module, the physical/chemical fate of the oil at sea. In order to estimate the hazard due to oil slicks for the Archipelago and Northern Sardinia shorelines, a two-years interannual experiment has been conducted. An hazard index, given by the ratio between the oil concentration reaching each predefined coastal cell and the maximum stranded concentration, has been computed and mapped by using geostatistic tools in GIS environment. Temporal and spatial variability as well as the climatological distribution of the hazard index were therefore described: this can be an useful information for local authorities in order to efficiently manage oil slick emergencies. A significant temporal and spatial variability has been observed in the distribution of the hazard index, showing highest values for winter months, in agreement with stronger wind-induced currents. Large hazard values were found mainly along westerly exposed shorelines, as expected considering the prevalence of westerly winds blowing through the Strait. In order to assess the risk, such a hazard index can be easily combined with quali-quantitative factors of vulnerability of the coastal environment, assuming the risk is the product of hazard and vulnerability. Two of the most important factors of vulnerability have been combined with the hazard index: the shores geomorphology and the level of environmental protection (proxy for the environmental value). The southern side of Spargi Island shows the highest risk values, because of coincident presence of large hazard index values, beaches presenting last classes of geomorphological vulnerability and a moderate/high level of protection. [Copyright &y& Elsevier]