1,721,427 research outputs found
Geomorphological survey for lagoon and coastal pond management projects: the Lagoon of Venice and the Orbetello coastal pond study cases
No full textRIASSUNTO
Questo lavoro riporta l'applicazione del rilevamento geomorfologico attraverso misure plano-altimetriche e batometriche ad alta risoluzione per differenti problematiche ambientali in due aree costiere: la Laguna di Venezia e lo stagno costiero di Orbetello. La programmazione di un piano di gestione e salvaguardia degli ecosistemi ha richiesto, per la laguna di Venezia, il monitoraggio delle tendenze evolutive' dei principali elementi morfologici, mentre per Orbetello la naturalizzazione di alcune casse di colmata. I rilevamenti topografici e batimetrici di dettaglio sono stati effettuati sia mediante strumenti e metodologie tradizionali sia mediante GPS in modalità statica-differenziale e cinematica-differenziale che ha permesso la visualizzazione dei dati in tempo reale ottenendo un diretto controllo delle misure. Queste metodologie, per il rilevamento topografico di alcuni limiti ed elementi morfologici inaccessibili,sono state integrate dal telerilevamento con foto aeree mentre, per la progettazione degli interventi di modella mento delle casse di colmata,dalla mappa tura dei sedimenti superficiali. Infine, la valutazione dei tassi erosivi e deposizionali, è stata effettuata sia con rilevamenti topografici stagionali sia con il confronto di una serie storica di cartografie e di foto aeree.
ABSTRACT
Environment management plans for lagoonal ecosystems require highly detailed geomorphological maps that cannot be obtained with the standard topographical survey. High resolution topographic and bathymetric measurements were carried out in the Lagoon of Venice and in the Lagoon of Orbetello (ItaIy) both with traditional methods and instrumentation and with DGPS (Differential Global Positioning System) in static and kinematic differential modes, with the purpose of providing the ecosystem management plans for the two lagoons, with detailed geomorphological data. For the Lagoon of Venice the detailed topographic and bathymetric surveys were required for the recognition and quantification of erosion and/or deposition processes active in the Venetian basin survey. The comparison of topographic and bathymetric surveys, since 1931, of aerial photographs and of all available information on the geomorphology of the area, has allowed the recognition and quantification, on a decadal scale, of the rate and trend of erosion and sedimentation and has made it possible to de fine those morphological boundaries impossible to survey due to the inaccessible soft mud. Three field measurements done during the 1996-1997 period have made possible the identification of the present erosion rate in a selected area of a salt marsh subjected to wave action. For the Lagoon of Orbetello very low scale topographic measurements were needed for the "naturalization" of manmade mud flats and salt marshes. The naturalization plan of five artificial islets, made with dredged sediments, required the detailed topographic measurements at very low scale of all the morphological elements in order to recreate a natural environment for a rich transitory, nesting or permanent bird life. In addition, sever l small creeks have been dredged for improve the hydrodynamics of the lagoon and the water exchallge between shallows in the 111art made islets and the main channels and to protect the bird life by making it inaccessible for man and other predacious animals. Overall the combination of traditional survey methods with DGPS and the use of all in house developed software has proved to be very efficient for producing the required for detailed topographic and bathymetric maps of the two study areas. Furthermore the study has provided the management plans for the two different ecosystems with geomorphological data otherwise not available.Published13-216A. Monitoraggio ambientale, sicurezza e territorioN/A or not JCRope
Geomorphological survey for lagoon and coastal pond management projects: the Lagoon of Venice and the Orbetello coastal pond study cases
No full textRIASSUNTO
Questo lavoro riporta l'applicazione del rilevamento geomorfologico attraverso misure plano-altimetriche e batometriche ad alta risoluzione per differenti problematiche ambientali in due aree costiere: la Laguna di Venezia e lo stagno costiero di Orbetello. La programmazione di un piano di gestione e salvaguardia degli ecosistemi ha richiesto, per la laguna di Venezia, il monitoraggio delle tendenze evolutive' dei principali elementi morfologici, mentre per Orbetello la naturalizzazione di alcune casse di colmata. I rilevamenti topografici e batimetrici di dettaglio sono stati effettuati sia mediante strumenti e metodologie tradizionali sia mediante GPS in modalità statica-differenziale e cinematica-differenziale che ha permesso la visualizzazione dei dati in tempo reale ottenendo un diretto controllo delle misure. Queste metodologie, per il rilevamento topografico di alcuni limiti ed elementi morfologici inaccessibili,sono state integrate dal telerilevamento con foto aeree mentre, per la progettazione degli interventi di modella mento delle casse di colmata,dalla mappa tura dei sedimenti superficiali. Infine, la valutazione dei tassi erosivi e deposizionali, è stata effettuata sia con rilevamenti topografici stagionali sia con il confronto di una serie storica di cartografie e di foto aeree.
ABSTRACT
Environment management plans for lagoonal ecosystems require highly detailed geomorphological maps that cannot be obtained with the standard topographical survey. High resolution topographic and bathymetric measurements were carried out in the Lagoon of Venice and in the Lagoon of Orbetello (ItaIy) both with traditional methods and instrumentation and with DGPS (Differential Global Positioning System) in static and kinematic differential modes, with the purpose of providing the ecosystem management plans for the two lagoons, with detailed geomorphological data. For the Lagoon of Venice the detailed topographic and bathymetric surveys were required for the recognition and quantification of erosion and/or deposition processes active in the Venetian basin survey. The comparison of topographic and bathymetric surveys, since 1931, of aerial photographs and of all available information on the geomorphology of the area, has allowed the recognition and quantification, on a decadal scale, of the rate and trend of erosion and sedimentation and has made it possible to de fine those morphological boundaries impossible to survey due to the inaccessible soft mud. Three field measurements done during the 1996-1997 period have made possible the identification of the present erosion rate in a selected area of a salt marsh subjected to wave action. For the Lagoon of Orbetello very low scale topographic measurements were needed for the "naturalization" of manmade mud flats and salt marshes. The naturalization plan of five artificial islets, made with dredged sediments, required the detailed topographic measurements at very low scale of all the morphological elements in order to recreate a natural environment for a rich transitory, nesting or permanent bird life. In addition, sever l small creeks have been dredged for improve the hydrodynamics of the lagoon and the water exchallge between shallows in the 111art made islets and the main channels and to protect the bird life by making it inaccessible for man and other predacious animals. Overall the combination of traditional survey methods with DGPS and the use of all in house developed software has proved to be very efficient for producing the required for detailed topographic and bathymetric maps of the two study areas. Furthermore the study has provided the management plans for the two different ecosystems with geomorphological data otherwise not available.Published13-216A. Monitoraggio ambientale, sicurezza e territorioN/A or not JCRope
I sedimenti tardo-quaternari dell'area litorale veneziana: analisi delle caratteristiche fisico-meccaniche
No full textAbstract: This paper describes the geotechnical properties of the Venetian littoral. Analyses of 110 cohesive soil samples and 338 granular, taken from 30 cores, 25-30 meters in depth, were considered. The classical geotechnical classification supported by statistical analysis has pointed out that the compression index presents the best correlations with void ratio index and natural water content. Moreover, this paper shows the importance of the Atterberg limits to distinguish the cohesive soils of the late Pleistocene from those of the Holocene. Granular sediments have shown a zonation of both the grain size distribution and permeability coefficient.
Resumé: Pour l'analyse des caractéristiques géotecniques du littoral venitien, qui est le sujet de ce travail, on a étudié 110 échantillons de terrains cohérents et 338 de terrains granulaires. Ces échantillons ont été prélevés de 30 carottages efféctués à la profondité moyenne de 25-30 m., et ils représentent les dernières 25.000-30.000 années de sèdiments quaternaires. En considérant la masse des donneés disponibles pour l'elaboration traditionnelle des propriétés géotechniques, une élaboration statistique a été utilisée pour obtenir des meilleures rélations de synthèse. En particulier, on a vu l'importance des limites de Attemberg pour effectuer la distinction entre les terrains cohérents du Pleistocene tardif et ceux de l'Olocene. En plus, la correlation du plus haut niveau de l'indice de compression est celle avec le pourcentage naturel d'eau et l'indice des vides. En ce qui concerne les terrains granulaires, on a verifié qu'il existe des zonations de la distribution granulometrique et du coeficient de perméabilité.
Riassunto: Per l'analisi delle caratteristiche geotecniche del litorale veneziano, argomento di questo lavoro, sono stati studiati 110 campioni di terreni coesivi e 338 di terreni granulari prelevati da 30 sondaggi terebrati lungo il cordone litoraneo a profondità medie di 25-30 metri che rappresentano gli ultimi 25.000-30.000 anni di sedimentazione quaternaria. In considerazione della massa di dati disponibili all'elaborazione tradizionale delle proprietà geotecniche si è affiancata un'elaborazione statistica (analisi discriminante) che ha permesso di fornire relazioni di sintesi maggiormente interpretative. In particolare è emerso il potere selettivo dei limiti di Atterberg per distinguere i terreni coesivi tardo-pleistocenici da quelli olocenici. Inoltre si è visto che l'indice di compressione presenta le correlazioni più elevate con il contenuto naturale d'acqua e l'indice dei vuoti. Per quanto concerne i terreni granulari si sono riscontrate zonazioni della distribuzione granulometrica e del coefficiente di permeabilità.Published47-606A. Monitoraggio ambientale, sicurezza e territorioN/A or not JCRope
I sedimenti tardo-quaternari dell'area litorale veneziana: analisi delle caratteristiche fisico-meccaniche
No full textAbstract: This paper describes the geotechnical properties of the Venetian littoral. Analyses of 110 cohesive soil samples and 338 granular, taken from 30 cores, 25-30 meters in depth, were considered. The classical geotechnical classification supported by statistical analysis has pointed out that the compression index presents the best correlations with void ratio index and natural water content. Moreover, this paper shows the importance of the Atterberg limits to distinguish the cohesive soils of the late Pleistocene from those of the Holocene. Granular sediments have shown a zonation of both the grain size distribution and permeability coefficient.
Resumé: Pour l'analyse des caractéristiques géotecniques du littoral venitien, qui est le sujet de ce travail, on a étudié 110 échantillons de terrains cohérents et 338 de terrains granulaires. Ces échantillons ont été prélevés de 30 carottages efféctués à la profondité moyenne de 25-30 m., et ils représentent les dernières 25.000-30.000 années de sèdiments quaternaires. En considérant la masse des donneés disponibles pour l'elaboration traditionnelle des propriétés géotechniques, une élaboration statistique a été utilisée pour obtenir des meilleures rélations de synthèse. En particulier, on a vu l'importance des limites de Attemberg pour effectuer la distinction entre les terrains cohérents du Pleistocene tardif et ceux de l'Olocene. En plus, la correlation du plus haut niveau de l'indice de compression est celle avec le pourcentage naturel d'eau et l'indice des vides. En ce qui concerne les terrains granulaires, on a verifié qu'il existe des zonations de la distribution granulometrique et du coeficient de perméabilité.
Riassunto: Per l'analisi delle caratteristiche geotecniche del litorale veneziano, argomento di questo lavoro, sono stati studiati 110 campioni di terreni coesivi e 338 di terreni granulari prelevati da 30 sondaggi terebrati lungo il cordone litoraneo a profondità medie di 25-30 metri che rappresentano gli ultimi 25.000-30.000 anni di sedimentazione quaternaria. In considerazione della massa di dati disponibili all'elaborazione tradizionale delle proprietà geotecniche si è affiancata un'elaborazione statistica (analisi discriminante) che ha permesso di fornire relazioni di sintesi maggiormente interpretative. In particolare è emerso il potere selettivo dei limiti di Atterberg per distinguere i terreni coesivi tardo-pleistocenici da quelli olocenici. Inoltre si è visto che l'indice di compressione presenta le correlazioni più elevate con il contenuto naturale d'acqua e l'indice dei vuoti. Per quanto concerne i terreni granulari si sono riscontrate zonazioni della distribuzione granulometrica e del coefficiente di permeabilità.Published47-606A. Monitoraggio ambientale, sicurezza e territorioN/A or not JCRope
Evidence of climatic variations in Upper Pleistocene and Holocene sediments from the Lagoon of Venice (Italy) and the Yellow Sea (China)
No full textThe effects of global climatic changes that occurred since the last Quaternary glaciation are recognizable in the stratigraphic sequences from several coastal zones in different locations around the world. The paleoevolution of the Northern Adriatic Sea and the Yellow Sea during the last 25,000 years has been characterized by several similar episodes of climatic changes. We report on the effects of climatic changes on the mineralogical composition and textural characteristics of clay and sand sedimentations in these paleoenvironments that are geographically far apart, correlating regional paleoclimatic changes with the mineralogical composition variations of sand and clay sequences. The mineralogical investigation has evidenced an increase of Quartz and Feldspar percentages and a decrease of Calcite and Dolomite during colder periods. Two depositional events, the hard clay layers and the cemented sand formations, that carry the imprints of the climatic conditions during their diagenesis are here reported and described. The hard clay layers represent the last continental sedimentation deposited during the Upper Pleistocene. The compactness of these clay layers is probably due to a long exposure to a cold and very dry climate. The water inside cemented sands studied were found under and outside of the Venice Lagoon and are similar to the beachrock formations presently found in tropical regions in intertidal zones. These cemented sands are remnants of ancient shorelines and witnesses of warm climate events.Published101-1126A. Monitoraggio ambientale, sicurezza e territorioN/A or not JCRope
Evidence of climatic variations in Upper Pleistocene and Holocene sediments from the Lagoon of Venice (Italy) and the Yellow Sea (China)
No full textThe effects of global climatic changes that occurred since the last Quaternary glaciation are recognizable in the stratigraphic sequences from several coastal zones in different locations around the world. The paleoevolution of the Northern Adriatic Sea and the Yellow Sea during the last 25,000 years has been characterized by several similar episodes of climatic changes. We report on the effects of climatic changes on the mineralogical composition and textural characteristics of clay and sand sedimentations in these paleoenvironments that are geographically far apart, correlating regional paleoclimatic changes with the mineralogical composition variations of sand and clay sequences. The mineralogical investigation has evidenced an increase of Quartz and Feldspar percentages and a decrease of Calcite and Dolomite during colder periods. Two depositional events, the hard clay layers and the cemented sand formations, that carry the imprints of the climatic conditions during their diagenesis are here reported and described. The hard clay layers represent the last continental sedimentation deposited during the Upper Pleistocene. The compactness of these clay layers is probably due to a long exposure to a cold and very dry climate. The water inside cemented sands studied were found under and outside of the Venice Lagoon and are similar to the beachrock formations presently found in tropical regions in intertidal zones. These cemented sands are remnants of ancient shorelines and witnesses of warm climate events.Published101-1126A. Monitoraggio ambientale, sicurezza e territorioN/A or not JCRope
Introduzione Parte V, Diritto Tributario
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L’ONERE DELLA PROVA
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