1,720,967 research outputs found
Holocene alluvial deposits and infrastructures: a methodology to determine hazard in urban areas
No full textAlluvial deposits are characterized by seismic wave amplification in case of earthquakes. In urban areas it’s important determine the geometry of the alluvial body to identify buildings in danger of yielding. This paper proposes a methodology to identify and define the alluvial deposits trough historical topography and analysis of few mechanical drillings if well scatterd and deep enough to reach the subsurface of the alluvial terrains. Through the vectorilizaton of contour lines of old topography preceding urban expansion, the production of the D.E.M. of the area and the determination of the upper limit of the alluvium by drillings, define the exact perimeter of the alluvial area. The subsurface of the alluvium has been drown on the data of the mechanical drillings following the contour lines’arrangement of the surface. The superimposition of this two areas originate a 3D surface geometry of the alluvial deposit. This methodology allows to identify the geological hazard of urban areas standing on alluvial deposits
Analisys of recent snow volumic mass and elevation of the threshold of natural skiability (lan) in the frioulan alps
No full textThe Friulian Alps show peculiar meteorologica and climatic features, deriving also from their geographic position between the northern Adriatic Sea to the South, the main Alpine watershed to the North (Tauern Alps) and the Carpathian belt to the East. Furthermore, there are many topoclimatic situations in relation to the geographic setting of the valleys carved between the main reliefs. This makes the Frioulian territory among the wettest in the entire Alpine region, with very abundant snowfall in relation to the moderate average altitude. Thanks to the availability of continuous and fairly homogeneously distributed historical series, a nivological characterization was carried out at the regional scale, with particular attention to the trend of the density of fresh snow, of the number of days with snow thickness higher than 30 cm and the consequent average elevation of the threshold of 100 skiable days (LAN). The ten snow fields under examination are located at elevations between 603 m. (Claut, Carnic Prealps) and 1843 m. (Rifugio Gilberti, Julian Alps); the analysed timespan goes from the winter season 1990-91 to the 2018-19. Surprising data resulted from this analysis. First of all, we noted that the volume mass (Kg /m3), which cannot be correlated with altitude, tends to a very light decrease (about 1.3 km/mc for year) in all the recording stations: this seems to be in contrast with the strong thermal increase that is occurring also on the Frioulian Alps (about 1.1°C in the same time span). Therefore, it’s very probable that in the last few years the thermal characteristics have changed, maybe together with the main origin of the air masses bringing snow in the study area. We also noted for all the stations an increase in the number of days with Hs> 30 cm: consequently, the average elevation of the limit of 100 days with natural ski possible is at about 1780 m a.s.l. and tends to decrease by about 7 meters per year (14 m in the nearby Slovenian Alps), even though it cannot be correlated with the aforementioned positive variation in temperatures and is in disagreement with the corresponding signals calculated for the northern side of the Alps
Comparison of methods for implementing high-resolution digital terrain models for reproducing the surface of glaciers.
No full textThe aim of the research is the tri-dimensional reconstruction of glacial topographic surfaces by the comparison of satellite images and traditional techniques, such as aerial photo images and topographic maps. The considered area La Mare Glacier (TN) East Alpes Italy, located in the Stelvio National Park, one of the Italian biggest national park. The double aim of the project is to validate and improve the techniques for the extraction of Digital Terrain Model (DTM) with a high morphologic complexity areas and to produce a DTM for studying, monitoring and quantifying the glacial resources. The DTM extracted from different sources will be integrated with GIS. Considering all the multi-disciplinary information that has been collected until now on this glacial areas, GIS represents the reference system for the analysis of the landscape changes
Automated DEM Extraction and Orthoimage Generation from EROS-A1 satellite images of Mt. Etna. Italy
No full textWe present a tri-dimensional reconstruction of the summit area of Mount Etna volcano using remote sensed images. The recent eruptions at Mt. Etna have drastically changed the morphology of the summit area. Thanks to Eros A1 satellite stereo images availability, we performed a DGPS survey for the collection of GPC (ground control point) useful to detect new topographic features necessary for the 3D model generation. Two types of GCP were collected: the first type were marked on new topographic features using reflectors visible from high resolution satellite camera (2 m x 2 m), the second type were collected using existing visible objects. The placement and marking of new reflectors have been necessary because the upper part of the volcano lacks of enough referenced features. We have therefore devised and placed a grid of new reflectors taking into account the slope characteristics of the volcano, in terms of elevation and visibility. The aim of the project is to validate and improve the techniques for the extraction of Digital Elevation Models (DEM) in areas charaterised by high morphologic complexity and to produce a DEM of Mt Etna for studying, monitoring and quantifying the volcanic changes. The extracted DEM has been quantitatively analysed in a GIS environment to obtain the up-to-date morphometry of the volcano
Metodologie a confronto per la realizzazione di High Resolution DEMs per la ricostruzione delle superfici glaciali
No full textVengono illustrate le metodologie utilizzate per la realizzazione di DEM ad alta risoluzione nella ricostruzione delle superfici glaciali
Un modello concettuale di banca dati per l’informatizzazione di carta geomorfologica
No full textSulla base di alcuni rilevamenti geomorfologici condotti e finalizzati alla realizzazione di cartografie digitali, è stato messo a punto un modello fisico di banca dati, al fine di rendere gli eventuali database geomorfologici utilizzabili per l’allestimento di carte geomorfologiche a diversa scala. Il modello di banca dati proposto prevede la possibilità di sfruttare le informazioni anche per realizzare carte geotematiche di vario tipo e per effettuare analisi geomorfologiche quantitative più specifiche (Cipolloni et alii, 2005a). Sono stati identificati 5 insiemi di informazioni, provenienti non solo dal database geomorfologico ma anche dagli archivi dei progetti CARG e IFFI. Il modello concettuale è stato sviluppato a partire dalle linee guida della carta geomorfologica alla scala 1:50.000 (AA.VV., 1994), implementando attributi utili alla gestione della cartografia a scala multipla e alla valutazione e analisi della cronologia dei processi morfogenetici
La struttura geologica dell’area romana e il Tevere.
No full textRoma, il Paleotevere e il corso attuale del Tevere. La crescita della città; i depositi alluvionali e i riporti. Il fiume e l'assetto strutturale del substrato. Processi alluvionali del Tevere dal XVI secolo al XX secolo. Le piene del Tevere del XVI secolo. Le piene del Tevere tra il XVII e il XVIII secolo. Le piene del Tevere nel XIX secolo. Le piene del Tevere nel XX secolo. Depositi alluvionali olocenici. Caratteri stratigrafici generali dei depositi alluvionali olocenici nella città di Roma. I modelli stratigrafici dei principali depositi alluvionali in Roma
3D modelling and visualization of geological structures in fold-and-thrust belts: an example from the Sabina area, Central Apennines
No full textIn the Sabina area, Central Apennines of Italy, faults and folds mainly accommodated high rates of crustal strain and shortening, during the Alpine orogeny from Middle-Upper Miocene to Lower Pliocene (Parotto & Praturlon, 1975; Cipollari & Cosentino, 1992). To improve our understanding of how faults and folds developed in the most internal portion of the outcropping sedimentary fold-and-thrust belt, where structures are highly non-cylindrical, and to test the reliability of 2D models to predict 3D subsurface structure, we are acquiring a 3D dataset for the quadrangle n. 366150 named “Vicovaro”, provided by the CARG project - the remaking of the Italian geological map. This 3D study is based on field geological data from the mapping of the “Vicovaro” quadrangle of the “Palombara Sabina” geological map, an area a few km northeast of Rome. From these data we constructed a set of parallel geological sections that resulted in this 3D visualization of subsurface structures. The 3D model has been reconciled into a coherent geological interpretation.Analyzing the resulting 3D model allowed us checking each section for consistency with respect to the other. Frequently, we were forced to reinterpret sections that we could have considered correct when thinking in 2 dimensions
A Landslide Susceptibility Map Based On Geomorphological And Morphometric Evaluation.
No full textThe aim of this work is within a detailed geomorphological approach (1:10.000 scale) to analyze the landslide susceptibility in a southern Italy zone (Rossano Calabro-CS) among the watershed of Colognati river and Coserie river. Geological and geomorphological field data had been performed in a G.I.S. environment by the morphometric analysis obtanied from high resolution digital terrain model. In the first step a land forms analysis has been conducted obtaining a strong relationship between geological settings, lithology and weathering. We distinguished fast phenomena (debris flows) by a trigger factor study on landslide top, landslide body and landslide foot, obtaing significant parameters: slope, lithology and prone parameters: high slope profile variations, soil thickness, geological and structural settings, hydrological features.The second step consisted in collecting data which have been crossed with morphological and geological zoning, giving a landslide susceptibility model
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