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61.
The velocity field in a river flow cross‐sectional area can be determined by applying entropy as done in 1978 by Chiu, who developed a two‐dimensional model of flow velocity based on the knowledge of maximum velocity, umax, and the dimensionless entropic parameter, characteristic of the river site. This is appealing in the context of discharge monitoring, particularly for high floods, considering that umax occurs in the upper portion of flow area and can be easily sampled, unlike velocity in the lower portion of flow area. The simplified form of Chiu's entropy‐based velocity model, proposed in 2004 by Moramarco et al., has been found to be reasonably accurate for determining mean flow velocity along each vertical sampled in the flow area, but no uncertainty analysis has been reported for this simplified entropy‐based velocity model. This study, therefore, performed uncertainty analysis of the simplified model following a procedure proposed by Misirli et al. in 2003. The flow velocity measurements at the Rosciano River section along the Chiascio River, central Italy, carried out for a period spanning 20 years were used for this purpose. Results showed that the simplified entropy velocity model was able to provide satisfactory estimates of velocity profiles in the whole flow area and the 95% confidence bands for the computed estimated mean vertical velocity were quite representative of observed values. In addition, using these 95% confidence bands, it was possible to have an indication of the uncertainty in the determination of mean cross‐sectional flow velocity as well. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
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The analysis of the physical processes involved in a conceptual model of soil water content balance is addressed with the objective of its application as a component of rainfall–runoff modelling. The model uses routinely measured meteorological variables (rainfall and air temperature) and incorporates a limited number of significant parameters. Its performance in estimating the soil moisture temporal pattern was tested through local measurements of volumetric water content carried out continuously on an experimental plot located in central Italy. The analysis was carried out for different periods in order to test both the representation of infiltration at the short time‐scale and drainage and evapotranspiration processes at the long time‐scale. A robust conceptual model was identified that incorporated the Green–Ampt approach for infiltration and a gravity‐driven approximation for drainage. A sensitivity analysis was performed for the selected model to assess the model robustness and to identify the more significant parameters involved in the principal processes that control the soil moisture temporal pattern. The usefulness of the selected model was tested for the estimation of the initial wetness conditions for rainfall–runoff modelling at the catchment scale. Specifically, the runoff characteristics (runoff depth and peak discharge) were found to be dependent on the pre‐event surface soil moisture. Both observed values and those estimated by the model gave good results. On the contrary, with the antecedent wetness conditions furnished by two versions of the antecedent precipitation index (API), large errors were obtained. Copyright © 2007 John Wiley & Sons, Ltd. 相似文献
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Cristina Ingarao Giovanna Lanciani Carmen Verri Tommaso Pagliani 《Marine pollution bulletin》2009,58(4):596-600
Prorocentrum lima (Ehrenberg) Dodge has been found for the first time during the summer of 2007 inside Ortona harbor and along the coast of the Abruzzo region, a slightly eutrophic area influenced by runoff from a nearby river. The investigations were conducted in two harbors and at six coastal sampling stations. Samplings were conducted using a phytoplankton net and with a pump. Average P. lima cellular concentrations were 3.2 × 104 cells L−1. Other well-known toxic and potentially toxic phytoplankton species have been considered. The number of toxic cells from net samples were higher than the numbers of toxic cell samples collected without the net. Occurrences of P. lima with abiotic factors revealed that temperature was positively correlated with P. lima abundance (p = 0.01), while salinity was highly negatively correlated with P. lima presence (p = 0.001). The total phytoplankton community was studied. 相似文献
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Tommaso De Pippo Carlo Donadio Micla Pennetta Carmela Petrosino Francesco Terlizzi Alessio Valente 《Geomorphology》2008,97(3-4):451-466
In the Northern Campanian coastal zone, over 150 km long, three geomorphic units are recognised: (1) sandy beaches that are well developed in the northern area, where a prominent river mouth (Volturno River) is also present; (2) steep and rocky shores, often with gravelly beaches or debris cones at their base, are mainly diffuse in the southern area (Sorrentine Peninsula); and, lastly, (3) “techno coast”, shorelines stabilized with revetments and seawalls as well as former natural environments no longer clearly operational because of urbanization, as is visible in Naples and in the Vesuvian coast. Six primary hazards are considered in this investigation: shoreline erosion, riverine flooding, storms, landslides, seismicity and volcanism, and man-made structures. These hazards do not have a uniform distribution along this coast in terms of their frequency and intensity; moreover both their interaction and the intensive action of humans, often uncontrolled, makes it difficult to assess the overall coastal hazard. In this paper a semi-quantitative method with which to quantify, rank and map the distribution of hazard is applied along this particular stretch of coast. In such a stretch, previously characterized in terms of types and processes and compartmentalized into geomorphic units, the effect of individual hazards, based on their magnitude and recurrence, is evaluated. Dominant and subordinate hazards for each geomorphic unit are identified, assigning a rank that is also a weighting. Comparison of each weighting through an interaction matrix permits the calculation of a resultant, which is the overall hazard assessment and which can be expressed cartographically. The results obtained for a coastal zone with one of the highest pressures from urbanization in the world, help us to recognise that this approach could become a useful tool to aid decision-making regarding coastal land-use and planning. 相似文献
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Benedetto?Badalamenti Nicola?Bruno Tommaso?Caltabiano Fabio?Di Gangi Salvatore?GiammancoEmail author Giuseppe?Salerno 《Bulletin of Volcanology》2004,66(1):80-89
Continuous monitoring of soil CO2 dynamic concentration (which is proportional to the CO2 flux through the soil) was carried out at a peripheral site of Mt. Etna during the period November 1997–September 2000 using an automated station. The acquired data were compared with SO2 flux from the summit craters measured two to three times a week during the same period. The high frequency of data acquisition with both methods allowed us to analyze in detail the time variations of both parameters. Anomalous high values of soil CO2 dynamic concentration always preceded periods of increased flux of plume SO2, and these in turn were followed by periods of summit eruptions. The variations were modeled in terms of gas efflux increase due to magma ascent to shallow depth and its consequent depressurization and degassing. This model is supported by data from other geophysical and volcanological parameters. The rates of increase both of soil CO2 dynamic concentration and of plume SO2 flux are interpreted to be positively correlated both to the velocity of magma ascent within the volcano and to lava effusion rate once magma is erupted at the surface. Low rates of the increase were recorded before the nine-month-long 1999 subterminal eruption. Higher rates of increase were observed before the violent summit eruption of September-November 1999, and the highest rates were observed during shorter and very frequent spike-like anomalies that preceded the sequence of short-lived but very violent summit eruptions that started in late January 2000 and continued until late June of the same year. Furthermore, the time interval between the peaks of CO2 and SO2 in a single sequence of gas anomalies is likely to be controlled by magma ascent velocity.Editorial responsibility: H. Shinohara 相似文献
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Addi Bischoff Markus Patzek Tommaso Di Rocco Andreas Pack Aleksandra Stojic Jasper Berndt Stefan Peters 《Meteoritics & planetary science》2023,58(10):1385-1398
On February 13, 2023, a huge fireball was visible over Western Europe (fireball event 2023 CX1). After the possible strewn field was calculated, the first of several recovered samples, with a mass of about 100 g, was discovered just 2 days after the fireball event on the ground of the village of Saint-Pierre-le-Viger. Meanwhile, more than 60 samples with a total mass of more than 1 kg were recovered and a piece of one of these is studied here. The fall occurred 220 years after the historic meteorite fall of L'Aigle on April 26, 1803, <120 km south. L'Aigle is the closest meteorite fall to Saint-Pierre-le-Viger and belongs to the same chondrite group. Both meteorites are breccias containing only clasts of high metamorphic degree (type 5 and type 6). Since only 20% of the L chondrites are breccias this coincidence is remarkable. As just mentioned, both samples studied from these rocks in this work are ordinary chondrite breccias and consist of equilibrated and recrystallized lithologies of petrologic type 6. The brecciated texture in L'Aigle, resulting in a remarkable light–dark structure, is more pronounced than the brecciated features in Saint-Pierre-le-Viger, from which also type 5 fragments have been reported. The compositions of low-Ca pyroxene and olivine grains in Saint-Pierre-le-Viger (Fs21.2 and Fa23.4, respectively) clearly require an L-group classification. L'Aigle was classified as an L6 breccia in the past, and this has now been confirmed by new data on low-Ca pyroxene and olivine (Fs20.7 and Fa23.8, respectively). Saint-Pierre-le-Viger contains local thin shock veins, and both meteorites are moderately shocked. Most olivines in the studied samples have planar fractures, but the estimated abundance of mosaicized olivines of 30%–40% among the large grains require a S4 shock classification. Oxygen isotope and bulk chemical data of Saint-Pierre-le-Viger certainly support the L chondrite classification. Bulk spectral data of Saint-Pierre-le-Viger are dominated by silicate minerals, that is, Fe-bearing low-Ca pyroxene, olivine, and plagioclase. Isotopic, chemical, and spectral data of the L'Aigle meteorite are shown for comparison and are very similar, providing additional circumstantial evidence of Saint-Pierre-le-Viger's L chondritic nature. 相似文献
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Fabian Zahnow Tido Stracke Tommaso di Rocco Thilo Hasse Andreas Pack 《Meteoritics & planetary science》2023,58(11):1567-1579
In this study, we present a method for high precision Δ′17O (Δ′17ORL = ln(δ17O + 1) – λRL ln(δ18O + 1)) analysis of small mass silicate and oxide materials. The analyses were conducted by laser fluorination in combination with gas chromatography and continuous flow isotope ratio monitoring gas spectrometry. We could analyze the oxygen isotope composition of samples down to 1 μg, which corresponded to about 13 nmol O2. The analytical error (we report the 1σ external reproducibility of a single analysis) in δ18O increases with decreasing sample sizes from ~0.2‰ for ~20 μg samples to ~0.9‰ for 1 μg samples. For Δ′17O, we achieved an external reproducibility of 0.04‰ for a sample mass range between 1 and 27 μg. The uncertainty in Δ′17O is smaller than the uncertainty in δ18O due to the correlated errors in δ17O and δ18O. We applied the method to urban micrometeorites, that is, small meteorites (<2 mm) that were sampled from a rooftop in Berlin, Germany. A total of 10 melted micrometeorites (S-type cosmic spherules, masses between 11 and 22 μg) were analyzed. The oxygen isotope compositions are comparable to that of modern Antarctic collections, indicating that the urban micrometeorites sample the same population. No indication for terrestrial weathering had been identified in the studied set of urban micrometeorites making them suitable materials for the study of micrometeorite origins. 相似文献
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Tommaso Campani Matteo Baini Matteo Giannetti Fabrizio Cancelli Cecilia Mancusi Fabrizio Serena Letizia Marsili Silvia Casini Maria Cristina Fossi 《Marine pollution bulletin》2013
This work evaluated the presence and the frequency of occurrence of marine litter in the gastrointestinal tract of 31 Caretta caretta found stranded or accidentally bycaught in the North Tyrrhenian Sea. Marine debris were present in 71% of specimens and were subdivided in different categories according to Fulmar Protocol (OSPAR 2008). The main type of marine debris found was user plastic, with the main occurrence of sheetlike user plastic. The small juveniles showed a mean ± SD of marine debris items of 19.00 ± 23.84, while the adult specimens showed higher values of marine litter if compared with the juveniles (26.87 ± 35.85). The occurrence of marine debris observed in this work confirms the high impact of marine debris in the Mediterranean Sea in respect to other seas and oceans, and highlights the importance of Caretta caretta as good indicator for marine litter in the Marine Strategy Framework Directive (MSFD) of European Union. 相似文献
70.
Tommaso Carlà Federico Raspini Emanuele Intrieri Nicola Casagli 《Environmental Earth Sciences》2016,75(24):1492
On December 3, 2013, a large complex landslide was triggered SW of the town of Montescaglioso (Southern Italy), causing the destruction of roads, commercial buildings and private dwellings, as well as several direct and indirect economic losses. A set of interferometric ground measurements acquired by the Cosmo-SkyMed satellite constellation and processed by means of the SqueeSAR algorithm was used to study the pre-event slope displacements in the entire Montescaglioso municipal area. Data span from January 30, 2012, to December 2, 2013, and show average line-of-sight velocities of 1–10 mm/year in the slope sector ultimately affected by the collapse. In retrospect, a time series analysis of the radar targets was performed in order to identify and characterize all the slope instabilities in proximity of the town. This was based on the setup of characteristic thresholds of displacement. The procedure permitted to locate several areas which recurrently exceeded these previously established thresholds, in consistency with the amount of precipitation. In particular, the major source of potential hazard in the area was indeed found where the December 3, 2013, landslide eventually occurred. The results of this quick data processing technique were validated through comparison with two independently developed landslide maps. This simple method, which is not supposed to diminish the importance of geomorphologic field surveys, could improve both the accuracy and the update rate of landslide susceptibility maps. Not relying on arbitrary or empirically derived approaches, it has the advantage of computing statistically based thresholds specific for each time series. By indicating the slope sectors in higher need of deeper in situ investigation, more support could be provided to administrative bodies for the processes of risk assessment and management. 相似文献