1,721,094 research outputs found
Probabilistic modelling of uncertainties in earthquake-induced landslide hazard assessment
No full textTECNICHE DI RILIEVO DIGITALE IN GROTTA. L’ESEMPIO DELLE GROTTE “GRAVE DEL PULO” E “GROTTA MARIO” DEL PULO DI ALTAMURA
No full textIl presente lavoro illustra alcune tecniche di rilievo
in grotta e di analisi dati per la proiezione di mappe 2D
georeferenziate e modelli 3D delle stesse. L’analisi dei
dati e l’elaborazione dei rilievi è effettuata con l’ausilio
di software specifici e open source. E’ presentato il rilievo
di due cavità ipogee del Pulo di Altamura: Grotta del
Pulo PU 1238 (Grotta Mario) e Grave del Pulo PU 860
(Inghiottitoio). La creazione di mappe 2D e modelli 3D
risulta essere un utile strumento in campo speleologico,
permettendo di acquisire una visione chiara della forma,
dell’andamento, delle dimensioni e delle caratteristiche
della cavità naturale senza dover necessariamente ricorre
a tecniche complesse di rilievo (ad es. laserscanning o fotogrammetria
digitale
Global Change-induced Agricultural Runoff and Flood Frequency Increase in Mediterranean Areas: An Italian Perspective
No full textInsights on the evolution of the “Torrente Gravina di Gravina” drainage-basin (southwestern Murge of Apulia, Italy) through quantitative analyses
No full textNear station topographic masses correction for high-accuracy gravimetric prospetting
No full textThe expanding role of gravity prospecting in mineral and hydrocarbon exploration as well as seismic and volcanic risk studies will be related to its ability to provide
high-resolution anomalies. To achieve this goal it is necessary to consider the errors resulting from the topographic corrections, in particular near-station effects. Such errors are relevant not only for severe topographies but also for relatively flat surfaces
involving microgravity applications and large-scale surveys.
Indeed, the errors introduced by low-resolution digital elevation models can be of
the same order of magnitude as the anomalies of interest. This basic fact is demonstrated by tests on synthetic models. The results of this analysis are summarized in an intuitive graph that can be used to estimate what near-station topographic resolution
is necessary for a specific survey. For the Vulcano Island test site (in Southern
Italy), we also compare results obtained using three different representations of the topographic surface with different horizontal resolutions and vertical precisions: one from existing photogrammetric data, the second from a digitized map and the third from a very high-resolution laser scanning system. Among the three methods, laser scanning is shown to obtain the highest resolution topographic reconstructions in the shortest time. Some weaknesses of the laser scanning methodology are discussed and we suggest ways of overcoming them
Medium-term sediment production and erosion rate in gullies of Fossa Bradanica, Basilicata [Produzione di sedimenti e tassi di erosione a medio termine nei "gullies" della Fossa Bradanica, Basilicata]
No full textGully erosion is an important soil degradation process in a range of environments, causing considerable soil loss and producing large volumes of sediment and it has a very significant contribution to total soil loss in Mediterranean areas. Nothwistanding its importance in the soil erosion processes, gully erosion has been long neglected because it is difficult to study and to predict. Consequently, there is a need for monitoring, experimental and modelling studies of gully erosion as a basis for predicting the effects of environmental change (climatic and land use changes) on gully erosion rates. A key issue to be addressed, as the basis for predicting the effects of global changes such as land use and climate changes, is the mapping and quantification of gully erosion and sediment production rates. At present no standardized procedures are available for measuring gully erosion rates and controlling factors. At the medium-time scale (10-70 years) aerial photographs have been analysed to measure temporal changes in length, area or volume of various gully tipes. In this respect, contribution has been the use of multi-temporal DEMs to map active gully areas and compute sediment production and deposition within gullies. In Basilicata (Southern Italy), agricultural soils underwent continuous degradation during the last century due to the highly erodible nature of outcropping terrains and to the anthropic pressure favoured by the introduction of Common Agricultural Policy (CAP) measures, which, especially in the last 30 years, has led to the reclamation of scrub lands and badlands for durum wheat cultivation. All these practices have accelerated the natural soil erosion processes, leading to the depletion of soil organic matter (i.e. reduction of soil structure stability) and favouring crusting, runoff production, gully erosion and shallow mass movements. On the basis of these considerations, some research questions remain open, the most importance one in Basilicata is: what is the contribution of gully erosion to overall soil loss and sediment production at different temporal and spatial scales and under different climatic and land use conditions? In this paper we attempt to answer to this question adopting the consolidate procedure in GIS to determine medium-term sediment production and deposition rates in a large gullies of Fossa Bradanica, Basilicata, Southern Italy. This method, which is based on the subtraction of multi-date elevation values from digital elevation model, does not produce significant errors in the estimetes and has been considered as a valide technique in the estimating net erosion in gully areas. Infact, in comparison with other methods, it also includes sediment produced by processes other than only overland flow, i.e. downcutting, headcutting, and mass movements and bank erosion
Investigating valley spacing dynamics in linear mountain fronts through terrain numerical modeling
No full text
Trend analysis of precipitation and drought in Basilicata from 1923 to 2000 within southern Italy context
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