1,721,023 research outputs found
Studio di dettaglio sulle aree della fascia costiera adriatica (settore italiano), che presentano le condizioni migliori per avviare lo studio avanzato sulla fattibilità del “sand engineering”
No full textConvenzione di ricerca tra Eni s.p.a. e il Dipartimento di Fisica e Scienze della Terra dell'Università di Ferrara (responsabile scientifico prof. Paolo Ciavola) - L’erosione costiera è un fenomeno sempre più costante lungo gran parte dei litorali dell’Europa e del mondo; in certe nazioni addirittura i processi erosivi mettono a serio rischio l’esistenza stessa dei centri abitati, od anche di vaste aree che sarebbero inondate qualora non fossero state prese adatte contromisure. L’esempio tipico è quello dei Paesi Bassi, dove da decenni ingenti risorse vengono impiegate per la protezione costiera e la ricerca su come difendersi in maniera sempre più efficace. Enormi passi avanti sono stati compiuti rispetto ai primi interventi: nel 2011, infatti, è stato realizzato per la prima volta nel mondo un ripascimento artificiale che ha coinvolto un enorme quantitativo di sabbia, circa 22 Mm3, il cosiddetto Sand Engine. Il vantaggio di questo mega-ripascimento è che dovrebbe assicurare per un periodo di 20 anni una buona alimentazione delle spiagge del litorale su cui è stato effettuato, nella fattispecie la Delfland Coast nei Paesi Bassi, senza necessità di ulteriori integrazioni come invece accade per i normali ripascimenti stagionali. Dati i risultati preliminari positivi del Sand Engine olandese, il presente studio è finalizzato alla ricerca di possibili siti sulla costa del Nord Adriatico dove poter realizzare un mega-ripascimento con criteri simili
A wireless waterproof RFID reader for marine sediment localization and tracking
No full textIn this paper an innovative RFID reader to be employed in marine sediment localization and tracking is presented. This device has been realized within the "Smart Pebble" project, where an RFID based solution is employed to measure the displacement of a swarm of pebbles during predefined periods, in order to analyze the dynamics of a beach under the effect of stormy events, and then the impact of coastal erosion on the studied stretch of coast. The reader described in this paper has been developed to facilitate the localization of the so-called Smart Pebbles, i.e. real pebbles taken from the beach under study and provided with an embedded RFID transponder, then positioned on and under the seabed. The developed device is able to detect the presence of a Smart Pebble up to a 50cm distance, and its functioning has been tested at depths up to 5 meters for prolonged spans of time (up to 4 hours). Moreover, a wireless connection based on IEEE 802.15.4 has been set up between the reader and a laptop to allow the wireless transfer of the transponder ID from the reader to a laptop positioned on the beach
Short term displacements of marked pebbles in the swash zone: Focus on particle shape and size
Full text linkIn this paper, two short term experiments with tracers on a mixed beach are presented. The aim was to understand how the size and shape of pebbles can affect their transport under low energy conditions. Sediment transport was studied by means of RFID technology to univocally monitor every single marked pebble. A size subdivision of injected pebbles was conducted based on three classes ("Big" from - 5.5 to - 6.5 phi; "Medium", from - 5 to - 5.5 phi; and "Small", from - 4.5 to - 5 phi). Two recoveries were realised 6 and 24 h after the injection. During a single day, the wave motion was very low in the first experiment and low to moderate in the second (never exceeding 0.4. m). The results showed that discs are less dynamic than spheres but can cover greater distances. Regarding the sediment size, "Big" pebbles are less dynamic if compared to finer classes, and they move preferentially down the swash zone towards the step or do not move up-slope if already at the step. Very low and steady energy conditions facilitate cross-shore and offshore movement of pebbles, rather than a slight raise in wave height producing predominant longshore transport even with non-marginal displacements. Low to moderate energy conditions can also produce some trend displacement based on the pebble shape even though T-tests showed that shape was not statistically significant for pebble displacement. The displacements of "Medium" and "Small" sized pebbles show a statistical dissimilarity compared to the "Big" ones. To refine the velocity estimation necessary to initiate pebble movement, the threshold velocity formulas known up to now should involve the shape parameter, especially for the short term. Better knowledge of the relationship between the sediment's characteristics and dynamics is critical to forecast the durability of replenishment material and to establish the suitability of fill material relative to native beach material. Hence, a better understanding of the role of particle characteristics is necessary
Esame della fascia costiera Adriatica (settore italiano). Studio di dettaglio sulle aree che presentano le condizioni migliori per avviare lo studio avanzato sulla fattibilità del “sand engineering”. FASE 2
No full textConvenzione di ricerca tra Eni s.p.a. e il Dipartimento di Fisica e Scienze della Terra dell'Università di Ferrara (responsabile scientifico prof. Paolo Ciavola) - Le ben note problematiche legate ai processi di erosione costiera mantengono alta l’attenzione sulle aree litorali, spesso investite da fenomeni di arretramento della linea di riva. Molteplici sono gli interventi adottati per ridurne l’impatto negativo, ma non sempre l’esito è risultato essere quello atteso o, altrimenti, un mero palliativo. Per questo motivo ultimamente è stata concepita l’idea di realizzare sulla costa emiliano-romagnola un ripascimento artificiale caratterizzato da quantitativi di sabbia molto maggiori rispetto a quelli effettuati sinora, secondo caso in Europa dopo quello sulla costa olandese: il cosiddetto Sand Engine. Dopo un primo studio di fattibilità volto alla selezione dei siti idonei all’attuazione del progetto, il presente lavoro è finalizzato a produrre una piena caratterizzazione delle dinamiche sedimentarie e morfologiche dei due tratti di litorale scelti come potenziali Sand Motors, ovvero Lido di Spina – Bellocchio a nord e Lido di Dante – Lido di Classe a sud. Report finale
TUMBLING EXPERIMENT FOR THE ESTIMATION OF ABRASION AND MASS LOSS OF COASTAL SEDIMENTS FROM AN ARTIFICIAL COARSE-CLASTIC BEACH
No full textAnalisi degli effetti della subsidenza indotta dalla coltivazione del giacimento di Dosso degli Angeli nella fascia costiera antistante la Laguna di Comacchio.
No full textConvenzione di ricerca tra Eni s.p.a. e il Dipartimento di Fisica e Scienze della Terra dell'Università di Ferrara (responsabile scientifico prof. Paolo Ciavola) - Lo scopo dello studio é la valutazione dell’impatto della riapertura del giacimento sulla fascia costiera su uno scenario a 30 anni, utilizzando il risultato delle simulazioni di subsidenza indotta dall’estrazione effettuate dall’Università di Padova per conto di Eni S.p.A. Il litorale in questione fa parte dell'unità fisiografica Casal Borsetti – Porto Garibaldi, comprendente l'apparato deltizio del Fiume Reno, area che soffre di forti fenomeni erosivi da circa 30 anni in seguito a fenomeni di subsidenza e ridotto apporto fluviale. Report finale
Analisi degli effetti della subsidenza indotta dalla coltivazione del giacimento “Agosta” sull’assetto della fascia costiera delle Vene di Bellocchio
No full textConvenzione di ricerca tra Eni s.p.a. e il Dipartimento di Fisica e Scienze della Terra dell'Università di Ferrara (responsabile scientifico prof. Paolo Ciavola) - Il sistema oggetto dello studio si riferisce all’unità fisiografica compresa tra il canale di Porto Garibaldi e la foce del Fiume Reno. In particolare l’assetto morfologico del sistema è stato indagato considerando la presenza dei processi erosivi in corso, il ruolo svolto dal Canale Gobbino, il comportamento morfologico dei bassi fondali e la sedimentazione sulla zona emersa delle Vene di Bellocchio. Pertanto sono stati eseguiti due rilievi topografici della porzione emersa della spiaggia e un’indagine morfobatimetrica dei bassi fondali antistanti le Vene di Bellocchio, per aggiornare i rilievi esistenti anche in seguito all’impatto della mareggiata eccezionale del 05 febbraio 2015, al fine di ricostruire in dettaglio la topografia del sistema morfologico nel suo complesso
Transport of marked pebbles in short periods of time on a coarse clastic beach (Marina di Pisa, Italy)
No full textTransport of coarse sediments on coarse clastic beaches still presents aspects that are not fully understood. For
instance, there is a generally perceived notion that during fair-weather periods coarse grains hardly move, if not
at all. The aim of this experiment is to prove that sediments such as pebbles are subject to significant shift in very
short lapses of time and under low energy waves. An artificial coarse clastic beach at Marina di Pisa (Tuscany,
Italy) was chosen as study site: Barbarossa beach is 110 m long and is bounded by two groynes. The mean grain
size is about 40-to-50 mm. About 80 pebbles were marked by means of the RFID technology, which enables to
univocally identify the tracers. The marked pebbles were released along cross-shore transects (one pebble each on
the fair-weather berm, on the beachface and on the step crest) on the morning of September 15th, and two recovery
campaigns were carried out after 6 and 24 hours from the injection. No particular wave activity was recorded
during the time frame of the experiment. After the first recovery campaign, which was performed 6 hours later
than the injection, about 94% of the pebbles were detected. After the second recovery campaign, 24 hours later,
the recovery rate decreased to 89%. Considering that the technique provides for detection of tracers within 50
cm, the resulting loss of pebbles after so brief spans of time is remarkable. The lack of detection of few tracers
implies that the transport rate that they experienced is not negligible. The highest rate of losses was recorded on
the beachface, the zone that is subjected the most to waves even under calm conditions. Pebble movement is also
confirmed by the fact that tracers detected after the first recovery campaign were not detected once again after the
second recovery campaign, and vice versa. The results of the experiment are useful to better define the transport of
coarse sediments, verifying that pebbles have to be expected be moving even in short periods of time
An RFID-based toolbox for the study of under- and outside-water movement of pebbles on coarse-grained beaches
No full textIn this paper the authors describe an innovative toolbox with an RFID-based automatic identification technology for tracking and analyzing pebble movements along coarse beaches. The developed system proposes utilizing several 'Smart Pebbles', embedded with an RFID transponder. Through an ad hoc waterproof device it was possible to detect the presence of these Smart Pebbles and calculate their exact position with a GPS device. Though RFID is a radio technology that is unsuitable under water, it can yet be developed to operate under water through certain modifications in the system. Performing several recovery campaigns over a long span of time, it was possible to trace the movements of the entire swarm of Smart Pebbles. All of the information gathered through the RFID system was then analyzed with an ad hoc software interacting with a database containing the movement data of every pebble. The software provided a graphic picture of the paths followed by all the Smart Pebbles and the same was utilized for calculating the distances covered by the pebbles
Implementing a coastal dune vulnerability index (CDVI) to support coastal management in different settings (Brazil and Italy)
Full text linkIn this paper, the vulnerability of two dune fields located in southern Brazil (São Francisco do Sul Island) and western Italy (Tuscany) has been defined through the
implementation of a Coastal Dune Vulnerability Index (CDVI). As the sites belonged to settings characterized by huge differences in terms of physical processes
(Atlantic Ocean and Mediterranean Sea), the index has been adapted accordingly to minimize the influence of the dissimilarities in an attempt to define potential
vulnerability parameters they might have in common. Five main groups of factors were taken into account in the design of the index: Geomorphological Condition of
the Dune system (GCD), Marine Influence (MI), Aeolian Effect (AE), Vegetation Condition (VC), and Human Effect (HE) for a total of 51 variables. A total vulnerability
index was calculated for each site. Cluster analysis and non-metric multidimensional scaling identified two main groups characterized by medium values of
vulnerability (0.32–0.49): as a result, the vulnerability of both sites can be defined as “medium”. In more detail, GCD turned out to be the most influent factor on both
settings; subordinately, marine influence also resulted relevant on the Oceanic site. The CDVI proved to be a flexible tool, as it was easily adjusted to work on such
different sites. In this sense it will be of great support to increase the awareness of coastal managers and decision makers about the mutual interactions of many
factors and processes that contribute to the evolution of coastal dunes regardless of the geographical setting
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