1,720,988 research outputs found
Land cover changes in abandoned agricultural land in the Northern Apennine (Italy) between 1954 and 2008: spatio-temporal dynamics
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Vegetation of abandoned areas in the northern Apennines (Italy): phytosociological aspects and biodiversity analysis
No full textSpectral characterization of coastal sediments using Field Spectral Libraries, Airborne Hyperspectral Images and Topographic LiDAR Data (FHyL)
No full textBeach dune systems are important for coastal zone ecosystems as they provide natural sea defences that dissipate wave energy. Geomorphological models of this near-shore topography require site-specific sediment composition, grain size and moisture content as inputs. Hyperspectral, field radiometry and LiDAR remote sensing can be used as tools by providing synoptic maps of these properties. However, multi-remote sensing of near-shore beach images can only be interpreted if there are adequate bio-geophysical or empirical models for information extraction. Our aim was thus to model the effects of varying sediment properties on the reflectance in both field and laboratory conditions within the FHyL (Field Spectral Libraries, Airborne Hyperspectral Images and Topographic LiDAR) procedure, using a multisource dataset (airborne Hyperspectral - MIVIS and topographic LiDAR - Hawk-eye II and field radiometry). The methodology consisted of (i) acquisition of simultaneous multi-source datasets (airborne Hyperspectral - MIVIS and topographic LiDAR - Hawk-eye) (ii) hyperspectral measurements of sediment mixtures with varying physical characteristics (moisture, grain size and minerals) in field and laboratory conditions, (iii) determination and quantification of specific absorption features, and (iv) correlation between the absorption features and physical parameters cited above.Results showed the potential of hyperspectral signals to assess the effect of moisture, grain-size and mineral composition on sediment properties
Sentinel-2 Reveals Record-Breaking Po River Shrinking Due to Severe Drought in 2022
Full text linkMonitoring inland waters is of critical importance for the effective and sustainable management of water resources, especially under climate change scenarios. This paper introduces a satellite-based approach for river monitoring using optical multispectral data. Time series of percentage water content, derived by the normalized difference water index (NDWI) calculated for each satellite acquisition, are aggregated at monthly timesteps to generate monthly water frequencies. Then, the river dynamics are evaluated by comparing each month with the previous one and with the average conditions of the same month in previous years. The ability of the method to investigate hydromorphological processes over time is demonstrated with the case study of the record-breaking Po River shrinking due to the severe 2022 drought in northern Italy, through the analysis of Copernicus Sentinel-2 satellite acquisitions. Earth observation data analysis is complemented with metrics generated from in situ river discharge measurements, including the coefficient of variation and the Streamflow Drought Index (SDI), to provide a more comprehensive understanding of the severity and variability of the hydrological drought throughout the year 2022. The findings demonstrate the satellite-based observation capabilities in monitoring surface waters, thereby stimulating the development of operational services like hydromorphological assessment
Understanding relationships between morphology and ecosystem structure in a shallow tidal basins of Venice lagoon
No full textCoastal wetlands represent complex ecosystems prone to continue fluctuation of their internal equilibrium. They
are valuable natural resources characterized by the continue interactions between geomorphological and biological
components. Their adaptation to changing conditions is highly dependent on the rate and extent of spatial and
temporal processes and their responses are still poorly understood. According to this, the vulnerability assessment
to natural and human made hazard have became fundamental to analyse the resilience of these areas, their ability
to cope with the impacts from externally driven forces or the efforts needed to minimize the impacts (Gitay et al.,
2011). The objective of this research is to develop a comprehensive and replicable method through the application
of Multi-Source data analysis, based on the integration of Earth Observation data and field survey, to analyse a
shallow tidal basin of salt marshes, located in the northern part of the Venice lagoon. The study site is charac-
terised by relatively elevated areas colonized by halophytic vegetation, and tidal flats, with not vegetated areas,
characterized by lower elevations. Sub-pixel processing techniques (Spectral Mixing Analysis – SMA) were used
to analyse the spatial distribution of both vegetation and sediments typology. Furthermore the classifications were
assayed in terms of spatial (Power law) and temporal (Empirical Orthogonal Functions) patterns, in order to find
the main characteristics of the aforementioned spatial trends and their variation over time. The principal aim is
to study the spatio-temporal evolution of this coastal wetland area, in order to indentify tipping points, namely
thresholds, beyond which the system reaches critical state and the main climatic, hydrodynamic and morphologi-
cal variables that may influence and increase this behaviour. This research represents a new approach to study the
geomorphological processes and to improve the management and conservation planning for coastal areas
Accuracy assessment of LAI, PAI and FCOVER from Sentinel-2 and GEDI for monitoring forests and their disturbance in Central Germany
No full textGoing Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
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