1,720,979 research outputs found
Small catchments evolution on clayey hilly landscapes in Central Apennines and northern Sicily (Italy) since the Late Pleistocene
No full textThe study aims to define a possible evolutionary geomorphological model of small catchments (i.e., <40 km2) that characterise the clayey hilly landscape of Central Apennines and Northern Sicily piedmont for the late Pleistocene–Holocene (i.e., the last 20,000 years, from the last glacial stage to the Holocene climate amelioration). The study is based on an integrated approach incorporating (i) geomorphological surveys and mapping, (ii) dating of Quaternary continental deposits, and (iii) topographical and morphometrical processing. It combines the data collected from previous published investigations as well as new data, specifically related to the availability of geo-chronological markers, and helps outline a common evolutionary model. The selected small catchments are tributaries of major rivers in inland areas (small catchments of the inland hills of Tuscany, Marche, and Sicily) or flow directly to the coast (coastal small catchments in Abruzzo). For each area, the geomorphological features (clay dominated bedrock, erosional landforms and fluvial terraces, and erosional/depositional strath terraces) and the dating of Quaternary deposits (from <50kyr to 15kyr) were compared, reconstructing the morphometry of the probable late Pleistocene landscape configuration. The analysis of the results showed that, although currently characterised by different climatic and geo-structural conditions, the different basins underwent a common geomorphological evolution mostly since the late Pleistocene. During the last glacial stage, under cold climate rhexistasy conditions, the small catchments were dominated by low gradient erosional surfaces with the deposition of fluvial, colluvial, or slope deposits, resulting in the formation of uniform slopes and wide minor valleys. The Holocene climate warming, together with marine transgression and tectonic uplift, induced the incision and dissection of the erosional surfaces and the continental deposits via gravitational movements and rapid erosion processes up until the present-day landscape configuration. The control factors of this evolution are most likely linked to the climate changes at the beginning of the Holocene and the interplay with the changes in the local base level of the small catchments since the late Pleistocene, combining late Quaternary tectonic uplift, sea-level rise, and river/coastal incision
Combining multi-typologies landslide susceptibility maps: a case study for the Visso area (central Italy)
Get PDFThe research proposes a simple but geomorphologically adequate method to produce a combined landslide susceptibility map. In fact, in a logic of real use, offering type-specific landslide susceptibility maps to land use planners and administration could be not a successful solution. On the other hand, the simple grouping of more types of landslides could be misleading for model calibration considering that the relationships between slope failures and geo-environmental predictors should be conveyed by the abundance of each type of landslide resulting not specific and diagnostic for each typology. In this test, after having produced independent models for flow, slide and complex landslide by exploiting MARS (Multivariate Adaptive Regression Splines) and a set of type-specific geo-environmental variables, a combined landslide susceptibility map was obtained by combining the scores of the three source maps. The combined map was finally validated with a new unknown archive, showing very good performances
Small catchments evolution on clayey hilly landscapes in Central Apennines and northern Sicily (Italy) since the Late Pleistocene
No full textThe study aims to define a possible evolutionary geomorphological model of small catchments (i.e., <40 km2) that characterise the clayey hilly landscape of Central Apennines and Northern Sicily piedmont for the late Pleistocene–Holocene (i.e., the last 20,000 years, from the last glacial stage to the Holocene climate amelioration). The study is based on an integrated approach incorporating (i) geomorphological surveys and mapping, (ii) dating of Quaternary continental deposits, and (iii) topographical and morphometrical processing. It combines the data collected from previous published investigations as well as new data, specifically related to the availability of geo-chronological markers, and helps outline a common evolutionary model. The selected small catchments are tributaries of major rivers in inland areas (small catchments of the inland hills of Tuscany, Marche, and Sicily) or flow directly to the coast (coastal small catchments in Abruzzo). For each area, the geomorphological features (clay dominated bedrock, erosional landforms and fluvial terraces, and erosional/depositional strath terraces) and the dating of Quaternary deposits (from <50kyr to 15kyr) were compared, reconstructing the morphometry of the probable late Pleistocene landscape configuration. The analysis of the results showed that, although currently characterised by different climatic and geo-structural conditions, the different basins underwent a common geomorphological evolution mostly since the late Pleistocene. During the last glacial stage, under cold climate rhexistasy conditions, the small catchments were dominated by low gradient erosional surfaces with the deposition of fluvial, colluvial, or slope deposits, resulting in the formation of uniform slopes and wide minor valleys. The Holocene climate warming, together with marine transgression and tectonic uplift, induced the incision and dissection of the erosional surfaces and the continental deposits via gravitational movements and rapid erosion processes up until the present-day landscape configuration. The control factors of this evolution are most likely linked to the climate changes at the beginning of the Holocene and the interplay with the changes in the local base level of the small catchments since the late Pleistocene, combining late Quaternary tectonic uplift, sea-level rise, and river/coastal incision
Assessment of Badlands Erosion Dynamics in the Adriatic Side of Central Italy
Get PDFBadlands are unique soil erosion landforms distributed in numerous geological, geomorphological, and climate contexts in several Mediterranean countries. The aim of this study was to map, classify, and analyze the temporal evolution of the badlands that crop out between the Tesino and Tronto Rivers in the Marche region, Central Apennines (Italy). In this study, 328 badlands landforms were mapped through Google Earth, orthophoto analysis (year 2016), and field surveys. Moreover, badlands were classified from a morphological point of view based on the active processes detected in the field. Additionally, badlands were studied from a lithological point of view, meaning they were strictly related to the soft sedimentary formations of the study area. Subsequently, through the analysis of a 10 × 10 m DEM, the most significant morphometric indices were extrapolated and badlands were classified. Finally, through the orthophotos from 1988, another badlands dataset was created and the area of each landform was compared with respect to the orthophotos from 2016. The multi-temporal air photo analysis, combined with the NDVI results, identified a general reduction trend in badlands areas, with increases in green cover and dense vegetation and changes in badlands morphotypes
Gully Erosion Development in Drainage Basins: A New Morphometric Approach
Get PDFThe formation and evolution of management gullies is a highly intense process of soil erosion often overlooked in policies and river basin strategies. Despite the worldwide spread of the phenomenon, our ability to assess and simulate gullying and its impacts remains limited; therefore, predicting the development and evolution of these river reaches represents a significant challenge, especially in areas where the loss of productive soil or the hazards linked to landslides or floods represent critical factors. Our study demonstrates how an exclusively morphometric approach, based on the construction of the hypsometric curve and applied to small hydrographic basins that are lithologically homogeneous and hierarchized according to the Strahler classification method, is able to predict the triggering height of the gullies; this height corresponds to the mean elevation of the basin and the inflection point of the hypsometric curve itself, confirming the hypothesis that this point coincides with the point at which a sudden change in surface runoff energy occurs, The study also shows that the portion of the basin necessary to trigger these intense erosive processes is always within a small range, regardless of the size and morphology (slope) of the basin itself. Such an approach, which is quick and relatively easy to apply, could help develop hydrogeological hazard mitigation practices in land planning projects
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
Get PDF“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
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
From traditional to modern ‘full coverage’ geomorphological mapping: a study case in the Chienti river basin (Marche region, central Italy)
Get PDFThe present work contributes to the process of modernization of traditional geomorphological mapping, a fundamental tool for the assessment of the hazard degree of natural processes for the planning, of works and infrastructures. Starting from a traditional and detailed geomorphological survey and through elaborations in a GIS environment, this paper presents a multiscalar cartography model, characterized by a ‘full coverage’ representation of landforms. These characteristics make it possible to upscale or downscale processes and landforms and to use different information levels created in a hierarchical form. The test site for the experimentation is located on the Adriatic side of central Italy and is represented by a small catchment, about 13 km2 large. All geomorphological features and information have been organized as elements and attributes within digital geomorphological information layers, following structured on a Digital Terrain Model derived from LiDAR; this new product is here proposed also as web-browser version
- …
