1,721,064 research outputs found
Suspended sediment load during floods in a small stream of the Dolomites (Northeasteran Italy)
No full textHypsometric Analysis of Headwater Rock Basins in the Dolomites (Eastern Alps) Using High-Resolution Topography
No full textHypsometric curves and integrals are effective tools for rapid quantitative assessments of topography. High-resolution digital terrain models derived from airborne LiDAR data have been analysed to study the hypsometry of small headwater rock basins (drainage areas up to 0.13 km2) in three study areas in the Dolomites (Eastern Alps) that have similar lithologies and climatic conditions. Hypsometric curves in the studied rocky headwaters display a variety of shapes and present remarkable differences between neighbouring basins. Hypsometric integrals show generally high values in the three study areas (>0.42, mean values between 0.51 and 0.65). The extent of the scree slopes located at the foot of rock basins in the three study areas is larger in the area with lower hypsometric integrals and indicates consistency between the development of basin erosion, which is shown by the hypsometric integral, and debris yield, represented by the extent of scree slope. No clear relations were observed between the hypsometric integrals and basin area and shape. When extending the analysis to larger basins, which encompass rocky headwaters and downslope soil-mantled slopes, a negative correlation is found between the hypsometric integral and catchment area, suggesting that the scale independency of the hypsometric integral occurs essentially in headwater rock basins. Geomorphometric indices (residual relief and surface roughness) have contributed to interpreting the variability of surface morphology, which is related to the geo-structural complexity of the catchments. © 2014 Swedish Society for Anthropology and Geography
Hydrological control on the triggering of debris flows in alpine catchments: storm analysis and basin response variability
No full textThree storm events, occurred in 2006, 2007 and 2009 in the upper Adige River basin (Eastern Alps, northern Italy) have been analyzed. The first storm system (4 October 2006) generated a flash flood with almost no debris flows and landslides, the second (21 June 2007) triggered a large number of debris flows and was characterized by a relatively minor runoff response, and the third (4 September 2009) resulted in both a relevant flash flood response and debris flows in minor streams. A strong interest both for civil protection and research purposes has been devoted by local authorities and researchers to such events. The study methods include radar rainfall analysis, hydrological modeling and {GIS} processing of spatial rainfall data and debris-flow locations. Precise information on debris-flow location and related volumes were derived from a geo-spatial database of instability phenomena implemented and managed by the Autonomous Province of Bolzano. Patterns of rainfall distribution and relations between the main hydrological variables (cumulative rainfall, intensity and antecedent moisture) have been analyzed to explain differences in catchments responses between the three studied events. Radar rainfall data have permitted to analyze rainfall fields with high spatial resolution, taking into account also the elevation variability of rainfall rates. The striking responses' contrast among the three events is related to differences in antecedent moisture, space-time structure of the rainstorms, cumulative rainfall and intensity distributions and temperature regime. The frequency analysis of the main hydrological variables revealed to be a powerful tool capable of distinguishing, within a synoptic framework, the space-time-magnitude variability of the events, so as to highlight the differences in flood and debris-flow response
Editorial: Lung Ultrasound and COVID-19 Interstitial Pneumonia in Different Medical Care Settings
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Multi-temporal analysis of sediment source areas and sediment connectivity in the Rio Cordon catchment (Dolomites)
No full textIn this study, two sediment source inventories produced in 1994 and 2006 have been compared and an analysis of sediment connectivity has been carried out in a 5 km2 headwater catchment (Rio Cordon catchment, Eastern Italian Alps). The 2006 sediment sources inventory was produced through an integrated approach encompassing field survey and interpretation of geomorphometric parameters (i.e., openness, surface roughness and wetness index) computed on a LiDAR-derived 1-m resolution DTM. The 2006 inventory aimed at updating a sediment source dataset dating back to 1994, which had been implemented by means of traditional techniques, i.e., field survey and interpretation of aerial photographs. Moreover, a topography-based index of connectivity (Cavalli et al., 2013) has been applied in order to evaluate the potential connection of 2006 sediment source areas with regard to the channel network. The analysis indicates that using a geomorphometric approach based on highresolution LiDAR DTM in combination with field survey helps obtaining reliable and detailed sediment sources inventory and improving sediment delivery assessment
Geomorphic change detection in small Alpine basins using LiDAR DTMs
No full textMorphological change evaluation of earth surface through time is an important task in environmental monitoring and risk management. Methods devoted to the assessment of geomorphic changes can be used to identify geomorphologically unstable areas, to quantify processes intensity, and to compute sediment budgets. Digital elevation models (DEMs) built from repeated topographic surveys can be used to produce DEM of Difference (DoD) maps and to estimate volumetric changes through time. Nowadays LiDAR technology can provide digital models representative of the bare earth surface (Digital Terrain Models – DTMs) at high spatial resolution and over great spatial extents contributing to the increase of accuracy of morphometric and volumetric measurement of varying surfaces.
In this study, high-resolution DTMs derived from airborne LiDAR data acquired in different years (2006 and 2011) were used in order to characterize the sediment transport processes such as debris flows and bedload transport in a small Alpine basin. Two DTMs (2 m resolution) were derived for the Gadria-Strimm catchment (Vinschgau/Venosta valley, Autonomous Province of Bozen-Bolzano, Italy). These catchments, which cover a total area of 14.7 km2, have been chosen due to their contrasting morphology and because they feature different types and intensity of sediment transfer processes: the Gadria creek is characterized by frequent occurrence of debris flows (almost one debris flow per year), whereas the Strimm channel is essentially a bedload stream.
A method based on fuzzy logic (Wheaton et al., 2010), which takes into account DTM uncertainties, was used to derive the DoD of the study area. The comparison between the 2006- 2011 DTMs permitted the analysis of the relationship between morphometric changes and the sediment transport dynamics at the basin scale over the 5 yr period. Besides, this approach proved useful to identify the relationship between erosion, deposition or no-change areas and geomorphometric parameters (e.g. slope, curvature, upslope area) relevant for sediment transport processes
Predicting debris flow occurrence in Eastern Italian Alps based on hydrological and geomorphological modelling
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The flash flood of October 2011 in the Magra river (Italy): Results of Post-Event documentation
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