1,354,210 research outputs found
The Po Delta is restarting progradation: Geomorphological evolution based on a 47-years Earth Observation dataset
No full textFrom the 1950s, the Po delta, one of the largest anthropogenic world deltas, has been subjected to a fast degradation and shoreline retreat due a marked reduction of sediment supply, mainly controlled by human impacts/factors, including subsidence. Through the interpretation of satellite images, coupled with the analysis of the flow discharge, and of the annual frequency of marine storms, we show that recently (>2010) the Po River has resumed delta progradation, especially in its northern portion. This happens after decades of erosion, followed by alternating regrowth and degradation phases, indicating conditions of substantial stability (1970-2000). Today the delta shows aggradation of new mouth-bars at the main distributary mouth, a clear evidence of active constructive processes. The ongoing trend marks a countertendency compared to many deltas worldwide
Morphological Analysis for Architectural Applications: Comparison between Laser Scanning and Structure-from-Motion Photogrammetry
No full textTerrestrial laser scanning (TLS) and structure-from-motion photogrammetry (SfM) can both provide dense and accurate point clouds. Therefore, they can be used to perform a morphological analysis of the façades of a masonry building, which relies on evaluation of the differences between the point cloud and a reference regular surface fitted to it. To compare TLS and SfM performance in morphological analysis, multimodal surveys were carried out on the square cross-section, 48-m-high Garisenda Tower in Bologna, Italy (reference surface: plane), and the circle cross-section, 42-m-high Caorle’s leaning bell tower in Venice, Italy (reference surface: moving cylinder). The results show that the TLS- and SfM-based morphologies are qualitatively the same, and the relative differences are lower than 10%–20% under the condition that the viewpoint positions (VPs) are optimal. Also, the overall geometries are correctly described by both the techniques. The main conclusion is that, if no particular constraints exist (e.g., unavoidable suboptimal VPs, night surveys are needed, or trees hide the surface), TLS and SfM have similar performance in morphological analysis
Solar radiation and ground temperature as factors affecting the transition from glacial to periglacial processes in the Dolomites: the case of Cima Uomo glacier
No full textGlaciers of the Dolomites are mostly small and hosted in
cirques. Most of them were progressively covered by large
amount of debris throughout the retreating phase occurred after the Little Ice Age (LIA). This has allowed their preservation even at relatively low altitudes. In some cases, these ice-debris systems are currently developing under permafrost conditions, leading to interesting examples of transition from glacial to periglacial morphodynamic processes
DEM e telerilevamento per lo studio geomorfologico delle pianure alluvionali
No full textAlluvial plains are characterized by a very low gradient relief and is difficult to detect their
morphologies from the terrain. Two methodologies are applied to study the geomorphology of the
venetian-friulian plane and the Murghab,s terminal fan (Turkmenistam): analysis of DEMs and
remote sensing images, acquired from satellite and aerial platform.. DEMs are the fundamental
input of the terrain modeling, but their theory references are relatively poor defined, especially in
low gradient area. The use of a methodology (DEM) where the uncertainty always exists, need a
synthesis of the conceptual model adopted in this research. The application of a methodology where
uncertain is always around the corner is needed to give a synthesis of the conceptual model adopted
in this research. The morphometric analyses on an apposite constructed DEM of the Venetian plain,
permit the automatic classification of the landforms, with a good level of coherence and detail.
Statistical analyses of the curvatures show their strong geomorphic meaning and can help to
distinguish the processes that, over time, have generate this complex system. The acquisition and
the processing of oblique aerial photographs in the part of friulian-venetian plain, crossed by the
roman road via Annia, give new results to investigate the paleohydrology and geoarcheology of this
area. Cropmark reveals, with extraordinary clearness, parts of the millenary interaction between
natural and human dynamics. Both methods are effective in the study of the geomorphological
evolution of the Murghab’s terminal fan. The morphological monotony of the distal part of the fan,
clashes with the complexity of the interactions between the processes that regulate their evolution.
The appropriate use of both the methodologies, followed by the validate on terrain, can give a
substancial contribute to the geomorphological study of alluvial plains.Le pianure alluvionali si caratterizzano per la debole inclinazione e le morfologie fluviali che le
costituiscono risultano difficilmente percepibili sul terreno. In questa ricerca, due metodologie sono
applicate allo studio gemorfologico della pianura veneto-friulana e di quella del Murghab
(Tukmenistan): l’analisi di DEM e di immagini telerilevate, da piattaforma satellitare e aerea. I
DEM costituiscono l’input fondamentale del terrain modeling ma il loro quadro di riferimento
teorico è relativamente poco definito. Nell’applicazione di un metodo (DEM) dove l’incertezza è
sempre latente, si sente il bisogno di fornire una sintesi dei modelli concettuali adottati in questa
ricerca. L’analisi morfometrica condotta sul DEM della pianura veneta, adeguatamente preparato,
consente la classificazione automatica delle morfologie con un buon grado di coerenza. L’analisi
statistica delle curvature dimostra il loro forte significato geomorfologico e si rivela d’ausilio per
caratterizzare i processi che nel tempo hanno generato le diverse superfici che costituiscono la
pianura. L’acquisizione e l’elaborazione di dati telerilevati di dettaglio nella bassa pianura venetofriulana
attraversata dalla via Annia (di epoca romana), che congiungeva le principali città dell’Alto
Adriatico, ha portato buoni risultati. I cropmark rivelano con straordinaria chiarezza “frammenti”
della millenaria interazione tra dinamiche naturali e antropiche in questa porzione di territorio.
Entrambi i metodi si sono rivelati efficaci nello studio dell’evoluzione geomorfologica del terminal
fan del Murghab. La monotonia morfologica che caratterizza le pianure contrasta con la complessità
delle interazioni tra i processi che ne controllano l’evoluzione. Un adeguato utilizzo incrociato di
entrambe le metodologie, seguito dalla validazione sul terreno, può fornire un sostanziale contributo
allo studio geomorfologico delle pianure alluvionali
Integration of LiDAR and optical remote sensing for the study of fluvial and anthropogenic landforms in the Brenta-Bacchiglione alluvial plain (NE Italy)
No full textThe geomorphological study of alluvial plains takes great advantage from the integration of detailed altimetry with
high resolution images, especially in the lower relief sectors, like those in the distal plain of the Brenta and
Bacchiglione rivers near the city of Padua (mean slope 0.4‰).The LiDAR data which were specifically acquired
for this research (Riegl LMS-Q560; mean density 7 points/m
1101
2
, over 123 km
2
), were classified and interpolated in
order to map fluvial and anthropogenic landforms. The DEM (z accuracy <5-10 cm) was processed and analyzed
in integration with high resolution oblique and vertical (VIS+IR) aerial images, acquired in specific seasonal time
windows, to maximize the vegetation response (cropmarks) to soils, deposits, and palaeohydrographic features.
A detailed field survey (hand augerings, soil profile description, deep borehole stratigraphy) was conducted to
validate the remote sensing interpretations.
The detailed topography allows to individuate low rise interfluves and scarps (<1-2 m), paleochannels, scroll bars
and crevasse splays. The reconstruction of the precise “ground” surface has allowed a better definition of the
geometry of the multi-stratified archeological mound in the historical center of Padua.
Cropmarks result the most appropriate to complete the mapping of the numerous fluvial forms, that have no
topographic relevance being smaller (i.e. minor crevasse channels and splays) and/or flatted by anthropic activity
(mainly ploughing). LiDAR intensity permits a precise individuation of LGM deposits that have shown peculiar
reflectivity related to specific soil characteristics (i.e., presence of calcic and argillic horizons).
At this scale (cell size <0.5-1 m) the real complexity of this highly anthropized low plain environment fully
emerges. The results bring advances in the comprehension of the Holocene evolution of the Brenta-Bacchiglione
plain, also in close relation to ancient settlements
UAV application for monitoring the annual geomorphic evolution of a coastal dune in Punta Marina (Italy)
No full textUnmanned Aerial Vehicles (UAV) allow to gather detailed topographic data at low cost over large survey areas. The study site, located in Punta Marina (Emilia-Romagna), is one of the few regional coastal locations still characterized by “natural” dunes; in 2015 a preservation scheme was realized to protect the dune system and reduce the erosion and vegetation degradation generated by beach users. Four UAV surveys were performed using a commercial DJI Phantom 3 Professional, a quadcopter equipped with the standard digital camera of 12 megapixels (3.6 mm focal length). Drone surveys were supported by a RTK-GNSS, both for GCP measurements and drone-derived DSM validation. Orthophotos were obtained through photogrammetry processing with a geometric resolution of about 3 cm, generating a DEMs with a cell size of 5 cm. Dune morphology was compared by means of DoD processing to understand the geomorphological evolution and quantify the volume of sediments displaced. The most evident result is related to the growth of a small incipient dune fed by aeolian processes and enhanced by preservation measures (planted vegetation and wooden fence). A cumulative vertical growth of 0.5 m was locally measured after the monitoring period. The role played by the growth of pioneer plants in overestimating volume changes was quantified as +11%. The use of drone-derived images, combined with SfM algorithms, allowed to achieve a centimetric accuracy in the incipient dune analysis. This methodological approach can represent an efficient tool for coastal and landscape managers, both for mapping and risk assessment purposes at small spatio-temporal scales
Methodologies in a geomorphological approach: examples from the Venetian Po Plain
No full textThe principal aim of this paper is to indicate the more appropriate methodologies for geomorphological research in a «low plain» context. The methodologies are applied in two study cases: one is centered on the middle of the Bacchiglione River and the other on the Montegrotto Th ermae Neronian site; in both there are
strong interrelations between geomorphic processes and ancient cycles of human occupation. Thus in the areas of interest, stratigraphic records of buried soils are often associated with archaeological remains
Is the present the key to the future?
No full textThe empirical and conceptual relationships between Earth surface processes and global changes are very
complex. The concept that “the present is the key of the future” implies that we know enough the present to
be able to extend our knowledge forward to focus on the future. Field and remote observations on the
present-day Earth surface processes represent the methodological instruments for the forecasting. At the end
of the 1980s, the scientific community predicted a significant increase of global warming followed by changes
in the trends of related surface processes. Some processes, such as the Arctic and Antarctic snow melting are
now accelerating and even irreversible; thus these trends showthat we are nowin an ‘out of scale’ discontinuity
moment. Present-day measures and observations could be scarcely significant and may add uncertainty in the
prediction of future trends. The ‘out-of-scale’ trend raises a fundamental question regarding the present, since
it may provide a new angle of thought for contemporary theoretical approaches. The need for reducing the uncertainty
in the trends of future processes requires a deep rethinking of the current paradigms in order to consider
also the ‘out of scale‘ trends
La fotografia aerea obliqua per l'analisi geoarcheologica del territorio della via Annia
No full textLungo il tracciato della via Annia tra Adria e Aquileia sono stati eseguiti numerosi voli aerei dedicati con velivoli da turismo. Le fotografie aeree oblique sono state scattate in diverse condizioni stagionali e di uso del suolo. I crop mark risultano particolarmente efficaci nella detezione di tracce archeologiche sepolte e della paleoidrografia. Le foto oblique sono georiferite con GPS e raddrizzate mediante apposito software. Oltre al tracciato viario antico sono state mappate diverse tipologie di insediamenti e sistemazioni agrarie sepolte
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