1,720,959 research outputs found
Coastal flooding risk scenario for the city of Grado, northern Adriatic Sea
No full textSea level rise, along with fast urbanization, has significantly raised flood hazards in coastal areas due to both increased population and the frequent urgent situations encountered in the urban context (Neumann, 2015). Rigid defensive systems along shorelines, backshore, and perimeter embankments at the lagoon border must therefore undergo structural verification and accurate elevation control, adapted to the expected sea level rise over which extreme events emerge. In this regard, a thorough investigation was conducted on the city of Grado, located in the North Adriatic Sea and representing one of the most important coastline and heritage sites in Friuli Venezia Giulia. The city is located on a barrier island and is prone to flooding from both the sea and from the back lagoon. The examination of the historical dataset of mean sea level and maximum levels recorded between 1991 and 2022 allowed us to first obtain local elevation estimates while also including subsidence. The study then looked at the duration of annual exceedance of the minimal threshold level of 110 cm, which marks Grado’s first significant marine ingression. Annual extremes were then processed using the Gumbel-type distribution law (Gumbel, 1958; Coles, 2001), which modulated the level thresholds with their respective return times for the location. Finally, the reconnaissance includes a downscaling examination of the impacts on the urban fabric, which is divided into regions of different vulnerability. Inundated areas were compared from high resolution DEMs using a GIS-based technique and a modeling approach utilizing MIKE software, analyzing both the magnitude and exposure of the urban setting to flood risk estimated for 2050 and 2100. As of today, approximately 56% of Grado’s inhabited area is inundated with a sea level threshold value of 151 cm, which occurs during surge episodes with a 30-year return period. By 2100, with an optimistic forecast (SSP1-2.6) of local sea level rise of around +50 cm, the same threshold will be met with events with a 30 times shorter return time. As a result, by 2100, 56% of the land area will be submerged at least once a year due to 101 cm surges. Extreme levels linked with more catastrophic events with secular recurrence times will be achieved on a multiyear basis, flooding more than 70% of the urbanized area. This makes it more important than ever to develop proper adaptation measures from the outset. The simulations developed are thus essential for medium to longterm urban planning, with the goal of securing the city, which, like Venice, is indicative of the processes that may affect other coastal realities and historical cities of great national worth
Occurrence and speciation of mercury in the recent sediments of the western coastal area of the Gulf of Trieste (northern Adriatic Sea): is the legacy of historical mining still present?
No full textMercury (Hg) contamination in the northern Adriatic Sea (Italy) is still an issue of environmental concern due to historical mining at Idrija (Slovenia) which was the second largest Hg mine worldwide (Covelli et al., 2001). The Isonzo/Soča River inputs continue to convey mercury-enriched particles into the coastal area where the element was accumulated in the sediment compartment and transported longshore towards the nearby Marano and Grado Lagoon (Covelli et al., 2007).
This study is focused on the surface sediments from the coastal area in front of the eastern sector of the Marano and Grado Lagoon, where a nearshore depositional system made up of relict and active migrating sandbanks extends up to 2 km seawards from the beachfront (Bezzi et al., 2021). The primary aim of this research is to evaluate the occurrence and distribution of Hg in the surface sediments, their grain size composition and potential relationships between Hg concentrations and the prevalence of distinct grain size fractions. Since sediments may also act as a secondary source of contamination due to biogeochemical processes at the sediment-water interface and resuspension events induced by both natural and anthropogenic factors, Hg speciation through thermal desorption technique (Petranich et al., 2022) was also performed to identify the main Hg compounds.
A total amount of 122 surface sediment samples was collected and analysed for grain size composition and total Hg (THg). Mercury (Hg) speciation analysis was applied as well on a subgroup of samples which were selected following both statistical and geographical criteria.
Sand is the most common mean grain size in the central sector of the investigated area whereas the eastern and western ends are dominated by the silty fraction. The concentration of THg in the sediments varies widely, ranging overall from 0.16 to 59.1 μg g-1. Overall, the highest concentrations of THg were observed in the sediments showing a prevalent very fine sand fraction, most likely due to the occurrence of detrital form of Hg (cinnabar particles). This evidence was confirmed by the speciation analyses which identified cinnabar (α-HgS) and metacinnabar (β-HgS) as the main Hg species in sediments thus testifying to a generally scarce mobility of the element present as a sulphide. This evidence supports the hypothesis that the effects of a resuspension event would be negligible in terms of increase of dissolved Hg in the water column and we could expect a rapid settling back of Hg to the sea bottom in association with the sediment particles
Quantifying transgressive coastal changes using UAVs: dune migration, overwash recovery, and barrier flooding assessment and interferences with human and natural assets
Full text linkThe advantages derived from the use of Uncrewed Aerial Vehicles (UAVs) are well-established: they are cost-effective and easy to use. There are numerous environmental applications, particularly when monitoring contexts characterized by rapid morphological changes and high rates of sediment transport, such as coastal areas. In this paper, three different case studies of survey and monitoring with high resolution and accuracy obtained through the use of UAVs are presented; these concern transgressive coastal sites. Results allow for the definition and quantification of coastal landforms and processes, including: (i) The anatomy of a parabolic dune and the rate of landward migration that could interfere with a tourist settlement; (ii) The mode and timing of morphological recovery and realignment of a barrier island overwashed by storm surge episodes; and (iii) The potential flood risk of a progradational spit that is a nesting site of a species of migratory breeding birds of conservation concern. The results demonstrate and confirm that, through a good coupling of drone-sensed quality data and accurate topographic control, quantitative estimates that are useful in assessing the impacts of natural processes involving both human and natural assets can be obtained
Coastal Storm-Induced Sinkholes: Insights from Unmanned Aerial Vehicle Monitoring
Full text linkIn recent decades, the scientific community has increasingly focused on extreme events linked to climate change, which are leading to more intense and frequent natural disasters. The Mediterranean can be considered a hotspot where the effects of these changes are expected to be more intense compared to other regions of the planet. Italy is not exempt; in fact, with its extensive shoreline, it is particularly vulnerable, especially to high sea levels and coastal erosions. In this framework, from late October to early November 2023, six storm surges occurred in the Gulf of Trieste (NE Italy). These events, characterized by winds from 190°N to 220°N and the significant wave height, which reached up to 1.81 m nearshore—an uncommon meteorological condition in the northern Adriatic Sea—caused the occurrence of eight coastal sinkholes and substantial damages to man-made structures. Thanks to Unmanned Aerial Vehicles (UAVs) and their derived products (high-resolution orthomosaics, Digital Elevation Models—DEMs, and point clouds), it was possible to study these features over time, enabling long-term coastal dynamics monitoring, which can be crucial for timely and effective response and restoration efforts
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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