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1.
Large landslides and deep-seated gravitational slope deformations (DSGSD) represent an important geo-hazard in relation to the deformation of large structures and infrastructures and to the associated secondary landslides. DSGSD movements, although slow (from a few millimetres to several centimetres per year), can continue for very long periods, producing large cumulative displacements and undergoing partial or complete reactivation. Therefore, it is important to map the activity of such phenomena at a regional scale. Ground surface displacements at DSGSD typically range close to the detection limit of monitoring equipment but are suitable for synthetic aperture radar (SAR) interferometry. In this paper, permanent scatterers (PSInSAR?) and SqueeSAR? techniques are used to analyse the activity of 133 DSGSD, in the Central Italian Alps. Statistical indicators for assigning a degree of activity to slope movements from displacement rates are discussed together with methods for analysing the movement and activity distribution within each landslide. In order to assess if a landslide is active or not, with a certain degree of reliability, three indicators are considered as optimal: the mean displacement rate, the activity index (ratio of active PS, displacement rate larger than standard deviation, overall PS) and the nearest neighbor ratio, which allows to describe the degree of clustering of the PS data. According to these criteria, 66% of the phenomena are classified as active in the monitored period 1992–2009. Finally, a new methodology for the use of SAR interferometry data to attain a classification of landslide kinematic behaviour is presented. This methodology is based on the interpretation of longitudinal ground surface displacement rate profiles in the light of numerical simulations of simplified failure geometries. The most common kinematic behaviour is rotational, amounting to 41 DSGSDs, corresponding to the 62.1% of the active phenomena. 相似文献
2.
Martina Anelli Tommaso Julitta Luca Fallati Paolo Galli Micol Rossini Roberto Colombo 《国际地球制图》2019,34(5):459-472
Photogrammetry represents a non-destructive, cost-effective tool for coral reef monitoring, able to integrate traditional remote sensing techniques and support researchers’ work. However, its application to submerged habitats is still in early stage. We present new ways to employ Structure from Motion techniques to infer properties of reef habitats. In particular, we propose the use of Digital Surface Models and Digital Terrain Models for assessing coral colonies extension and height and discriminating between seabed and coral cover. Such information can be coupled with digital rugosity estimates to improve habitat characterization. DTM, DSM and orthophotos were derived and used to compute a series of metrics like coral morphologies, reef topography, coral cover and structural complexity. We show the potentialities offered by underwater photogrammetry and derived products to provide useful basic information for marine habitat mapping, opening the possibility to extend these methods for large-scale assessment and monitoring of coral reefs. 相似文献
3.
Alfredo Gallego Virginia L. Gemini Susana L. Rossi Carlos E. Gómez Gustavo D. Bulus Rossini Sonia E. Korol 《洁净——土壤、空气、水》2011,39(8):774-780
An indigenous bacterial strain of Delftia sp. capable of degrading 2,4‐dicholorophenol and an indigenous bacterial community that degrades 2,4,6‐trichlorophenol (TCP) were employed to inoculate continuous down‐flow fixed‐bed reactors. Continuous‐reactors were constructed from PVC employing hollow PVC cylinders as support material. Synthetic wastewater was prepared by dissolving the corresponding chlorophenol in non‐sterile groundwater. Biodegradation was evaluated by spectrophotometry, chloride release, GC, and microbial growth. Detoxification was evaluated by using Daphnia magna as test organism. Delftia sp. was able to remove an average of 95.6% of DCP. Efficiency in terms of chemical oxygen demand (COD) was of 88.9%. The indigenous bacterial community that degrades TCP reached an average efficiency of 96.5 and 91.6% in terms of compound and COD removal, respectively. In both cases stoichiometric removal of chloride and detoxification was achieved. When synthetic wastewater feed was cut off for 7 days, both reactors showed a fast recovery after inflow restarting, reaching average outlet concentration values within 36 h. The promising behavior of the microorganisms and the low cost of the reactors tested allow us to suggest their possible application to remediation processes. 相似文献
4.
G. Mastrantonio A. P. Viola S. Argentini G. Fiocco L. Giannini L. Rossini G. Abbate R. Ocone M. Casonato 《Boundary-Layer Meteorology》1994,71(1-2):67-80
In the period June–July 1992, four Doppler sodars were operated simultaneously in Rome and the surrounding area. The data have been used to investigate the contributions from sea breeze events to the local low-level circulation. Three days in which synoptic-scale pressure gradients were weak have been selected. A number of characteristics of the sea breeze are examined including the onset and cessation of the phenomenon, the behavior of the wind speed, and the depth of the density flow. The time propagation of the events and the influence of orography are obtained from a comparison between the data at different sites. The low-level circulation in the early morning is associated with the land breeze and appears to be enhanced by a mountain wind from the surrounding hills. The observed behavior of the vertical velocity field associated with the sea breeze is consistent with model predictions. 相似文献
5.
Massimo Meneghetti Micol Bolzonella Matthias Bartelmann Lauro Moscardini Giuseppe Tormen 《Monthly notices of the Royal Astronomical Society》2000,314(2):338-347
We present the results of a set of numerical simulations evaluating the effect of cluster galaxies on arc statistics.
We perform a first set of gravitational lensing simulations using three independent projections for each of nine different galaxy clusters obtained from N -body simulations. The simulated clusters consist of dark matter only. We add a population of galaxies to each cluster, mimicking the observed luminosity function and the spatial galaxy distribution, and repeat the lensing simulations including the effects of cluster galaxies, which themselves act as individual lenses. Each galaxy is represented by a spherical Navarro, Frenk & White density profile.
We consider the statistical distributions of the properties of the gravitational arcs produced by our clusters with and without galaxies. We find that the cluster galaxies do not introduce perturbations strong enough to significantly change the number of arcs and the distributions of lengths, widths, curvature radii and length-to-width ratios of long arcs. We find some changes to the distribution of short-arc properties in the presence of cluster galaxies. The differences appear in the distribution of curvature radii for arc lengths smaller than 12 arcsec, while the distributions of lengths, widths and length-to-width ratios are significantly changed only for arcs shorter than 4 arcsec. 相似文献
We perform a first set of gravitational lensing simulations using three independent projections for each of nine different galaxy clusters obtained from N -body simulations. The simulated clusters consist of dark matter only. We add a population of galaxies to each cluster, mimicking the observed luminosity function and the spatial galaxy distribution, and repeat the lensing simulations including the effects of cluster galaxies, which themselves act as individual lenses. Each galaxy is represented by a spherical Navarro, Frenk & White density profile.
We consider the statistical distributions of the properties of the gravitational arcs produced by our clusters with and without galaxies. We find that the cluster galaxies do not introduce perturbations strong enough to significantly change the number of arcs and the distributions of lengths, widths, curvature radii and length-to-width ratios of long arcs. We find some changes to the distribution of short-arc properties in the presence of cluster galaxies. The differences appear in the distribution of curvature radii for arc lengths smaller than 12 arcsec, while the distributions of lengths, widths and length-to-width ratios are significantly changed only for arcs shorter than 4 arcsec. 相似文献
6.
Explosive events are commonly accompanied or followed byheavy rains. These eruption-induced storms together with thedeposition of large amounts of ash contribute to destabilise thehydrological cycle in the areas affected by volcanic eruptions.Flooding of the region surrounding the active volcano can easilyfollow, increasing the complexity of the volcanic crisis and itsmanagement. This is particularly true in the case of Vesuvius,that is not only characterized by a dramatic volcanic hazard, butit is also located within an area that is normally prone to flood hazard. A complete assessment of the impact associated with explosive volcaniceruptions should involve a flood hazard assessment for the region.This work represents a first attempt to address the problem: atopographically based rainfall-runoff model was here applied to theVesuvian area where two main sub-basins were analysed. The modelwas applied to evaluate the role of selected parameters on the totaldischarge at the basins' outlet. These parameters were chosen amongthose likely to be affected by an explosive event and were variedthrough a reasonable range. Results confirm that the deposition oflarge amounts of ash can affect the temporal evolution of the dischargeand its maximum value, for a given precipitation event. The simulationspresented outline the need for a detailed flood forecasting study for theVesuvian area, that should be included within the hazard mitigation strategies. 相似文献
7.
Ilaria Anna Maria Marino Federica Barbisan Micol Gennari Folco Giomi Mariano Beltramini Paolo Maria Bisol Lorenzo Zane 《Estuarine, Coastal and Shelf Science》2010
Heterogeneity in genetic composition among recruits, mostly due to a large variance in reproductive success mediated by oceanographic processes, has been reported for marine species but is less understood in coastal lagoons' organisms. Temporal genetic variation in natural populations of the Mediterranean shore crab Carcinus aestuarii was quantified over a multi-year sample. A total of 486 adult crabs were collected at eight different sites of the Venice Lagoon during the period 2005–2007 and screened for genetic variation using 11 microsatellite loci. Two additional samples (N = 115) from neighbouring sites, located approximately 100 km North and South to the Venice Lagoon, were included for the sake of comparison. Our results show significant differences in allelic frequencies at the micro-geographic scale of the Venice Lagoon, observed between sites of collection, typologies of habitat, and areas with different class of ecological risk or pattern of hemocyanin expression. However, this pattern was not constant between years, with significant differences observed mainly in 2005 and 2006, but not in 2007. Our results indicate significant temporal differences suggesting the existence of dynamic processes that act on the genetic pool of this species. Although natural selection and gene flow might play a role, we suggest that genetic drift linked to large variation in the reproductive success of individuals is the most probable scenario to explain the local genetic patterns of differentiation in the Mediterranean shore crab. Our study, by providing the first evidence for the existence of genetic differences in this species at the micro-geographic scale, suggests that a better comprehension of the link between reproduction, recruitment and oceanography is critical to understand how colonization and maintenance of genetic variation is achieved in ephemeral and vulnerable environments such as coastal lagoons. 相似文献
8.
Javier Blanco-Sacristán Cinzia Panigada Rodolfo Gentili Giulia Tagliabue Roberto Garzonio M. Pilar Martín Mónica Ladrón de Guevara Roberto Colombo Thomas P. F. Dowling Micol Rossini 《地球表面变化过程与地形》2021,46(12):2466-2484
Biocrusts (topsoil communities formed by mosses, lichens, bacteria, fungi, algae, and cyanobacteria) are a key biotic component of dryland ecosystems. Whilst climate patterns control the distribution of biocrusts in drylands worldwide, terrain and soil attributes can influence biocrust distribution at landscape scale. Multi-source unmanned aerial vehicle (UAV) imagery was used to map and study biocrust ecology in a typical dryland ecosystem in central Spain. Red, green and blue (RGB) imagery was processed using structure-from-motion techniques to map terrain attributes related to microclimate and terrain stability. Multispectral imagery was used to produce accurate maps (accuracy > 80%) of dryland ecosystem components (vegetation, bare soil and biocrust composition). Finally, thermal infrared (TIR) and multispectral imagery was used to calculate the apparent thermal inertia (ATI) of soil and to evaluate how ATI was related to soil moisture (r2 = 0.83). The relationship between soil properties and UAV-derived variables was first evaluated at the field plot level. Then, the maps obtained were used to explore the relationship between biocrusts and terrain attributes at ecosystem level through a redundancy analysis. The most significant variables that explain biocrust distribution are: ATI (34.4% of variance, F = 130.75; p < 0.001), Elevation (25.8%, F = 97.6; p < 0.001), and potential solar incoming radiation (PSIR) (52.9%, F = 200.1; p < 0.001). Differences were found between areas dominated by lichens and mosses. Lichen-dominated biocrusts were associated with areas with high slopes and low values of ATI, with soil characterized by a higher amount of soluble salts, and lower amount of organic carbon, total phosphorus (Ptot) and total nitrogen (Ntot). Biocrust-forming mosses dominated lower and moister areas, characterized by gentler slopes and higher values of ATI with soils with higher contents of organic carbon, Ptot and Ntot. This study shows the potential to use UAVs to improve our understanding of drylands and to evaluate the control that the terrain has on biocrust distribution. 相似文献
9.
The Phlegraean Fields caldera is an active volcanic system where episodes of ground deformation are accompanied by significant changes in geochemical and geophysical parameters monitored at the surface. These changes derive from a complex interaction between magmatic system and hydrothermal fluid circulation. We calculate the gravity changes associated with the variable density of hydrothermal fluids. We simulate the multi-phase and multi-component fluid circulation triggered by a pulsating magma degassing, periodically increasing the discharge of CO2-enriched fluids into the shallow hydrothermal system. The simulated evolution of the hydrothermal system successfully reproduces the observed composition of gas discharged at the surface. At the same time, results indicate that changes in average fluid density generate a detectable gravity signal that is of the same order of magnitude of the observed changes. This contribution to gravity changes can explain the peculiar behavior of gravity data collected at Solfatara, where surface hydrothermal phenomena are present. Simultaneous fitting of two independent sets of monitoring data (gas composition and gravity changes) confirms the conceptual model proposed for the hydrothermal system at Solfatara, and it provides new insights for the interpretation of gravity data. 相似文献
10.
A search for cheap and efficient method to monitor atmospheric particulates in city centres has raised new interest to measure foliar element concentrations after the role of particulate pollution for respiratory illnesses was discovered. Leaf samples of Golden dewdrop (Duranta repens L.) collected in Palermo (South of Italy) between 1998 and 2000 were analysed to study the possible use of this shrub as a passive biomonitor for atmospheric pollution in urban areas. Concentrations of Ba, Cd, Cu, Fe, Mg, Mn, Pb and Zn were determined from leaf samples collected from six sampling sites representing either (a) areas of high traffic density or (b) areas not directly affected by the city traffic (e.g. gardens). Most of the elements showed a significant temporal variation but no consistent trends could be seen, i.e. the highest (or lowest) values were not detected consistently at some particular time of the year. Furthermore temporal changes were of same magnitude in polluted versus less polluted areas; no statistically significant interaction between pollution level and collection period was detected. Pollution level (traffic density) was the primary factor to explain spatial variation only in the case of foliar Mg concentrations. On the other hand, variation in foliar concentrations between sampling sites (irrespective of the pollution level) was large. Our results suggest that particulate deposition needs to be quite high before spatial segregation can be done on the basis of foliar element concentrations. 相似文献