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31.
Matteo Vacchi Monica Montefalcone Chiara F. Schiaffino Valeriano Parravicini Carlo Nike Bianchi Carla Morri Marco Ferrari 《Marine pollution bulletin》2014
The upper portion of the meadows of the protected Mediterranean seagrass Posidonia oceanica occurs in the region of the seafloor mostly affected by surf-related effects. Evaluation of its status is part of monitoring programs, but proper conclusions are difficult to draw due to the lack of definite reference conditions. Comparing the position of the meadow upper limit with the beach morphodynamics (i.e. the distinctive type of beach produced by topography and wave climate) provided evidence that the natural landwards extension of meadows can be predicted. An innovative model was therefore developed in order to locate the region of the seafloor where the meadow upper limit should lie in natural conditions (i.e. those governed only by hydrodynamics, in absence of significant anthropogenic impact). This predictive model was validated in additional sites, which showed perfect agreement between predictions and observations. This makes the model a valuable tool for coastal management. 相似文献
32.
Marco Benvenuti Marco Bonini Giovanna Moratti Marianna Ricci Chiara Tanini 《Geomorphology》2008,100(3-4):269-284
Integration of geomorphology, stratigraphy, sedimentology and morphotectonics in the analysis of the lower Cecina River reach, coastal Tuscany, reveals an undocumented historical channel avulsion. Geomorphological evidence and radiocarbon dating support that, from the Last Glacial Maximum until the end of the 16th century, the Cecina River flowed north of the present course and formed a well-developed cuspate delta. Two concurrent factors, active tectonics as a preparing factor and discharge regime as an activation factor, are thus inferred to have favored the avulsion of Cecina River. Fragmentary archaeological and historical records indicate that the late Holocene Cecina River plain was virtually unpopulated until the latest 16th century. This seems the main reason why high-magnitude hydrological events and prominent river channel avulsions were not reported in historical chronicles. From this perspective, geomorphological data may provide important knowledge and understanding of recent dynamics of environmental change when historical record is lacking or missing. 相似文献
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Giampaolo Di Silvio Chiara Dall’Angelo Davide Bonaldo Giacomo Fasolato 《Continental Shelf Research》2010
This model is based on the concept of transport concentration, defined as the time-averaged concentration in a given location of a lagoon, which determines the long-term net transport of sediments as the sum of a dispersive and an advective flux. Dispersive net flux of sediments is due to the alternate components of the tidal flow, while the advective net flux of sediments is due to the residual (Eulerian) component of the tidal, fluvial and littoral flow and possibly to the asymmetry between flow and ebb tide. 相似文献
36.
Chiara Turino Paola Morasca Gabriele Ferretti Davide Scafidi Daniele Spallarossa 《Journal of Seismology》2010,14(2):393-411
Reliable automatic procedure for locating earthquake in quasi-real time is strongly needed for seismic warning system, earthquake
preparedness, and producing shaking maps. The reliability of an automatic location algorithm is influenced by several factors
such as errors in picking seismic phases, network geometry, and velocity model uncertainties. The main purpose of this work
is to investigate the performances of different automatic procedures to choose the most suitable one to be applied for the
quasi-real-time earthquake locations in northwestern Italy. The reliability of two automatic-picking algorithms (one based
on the Characteristic Function (CF) analysis, CF picker, and the other one based on the Akaike’s information criterion (AIC),
AIC picker) and two location methods (“Hypoellipse” and “NonLinLoc” codes) is analysed by comparing the automatically determined
hypocentral coordinates with reference ones. Reference locations are computed by the “Hypoellipse” code considering manually
revised data and tested using quarry blasts. The comparison is made on a dataset composed by 575 seismic events for the period
2000–2007 as recorded by the Regional Seismic network of Northwestern Italy. For P phases, similar results, in terms of both
amount of detected picks and magnitude of travel time differences with respect to manual picks, are obtained applying the
AIC and the CF picker; on the contrary, for S phases, the AIC picker seems to provide a significant greater number of readings
than the CF picker. Furthermore, the “NonLinLoc” software (applied to a 3D velocity model) is proved to be more reliable than
the “Hypoellipse” code (applied to layered 1D velocity models), leading to more reliable automatic locations also when outliers
(wrong picks) are present. 相似文献
37.
Modeling water resources of a highly irrigated alluvial plain (Italy): calibrating soil and groundwater models 总被引:1,自引:0,他引:1
Chiara Vassena Michele Rienzner Giansilvio Ponzini Mauro Giudici Claudio Gandolfi Cinzia Durante Davide Agostani 《Hydrogeology Journal》2012,20(3):449-467
Modern and effective water management in large alluvial plains that have intensive agricultural activity requires the integrated modeling of soil and groundwater. The models should be complex enough to properly simulate several, often non-linear, processes, but simple enough to be effectively calibrated with the available data. An operative, practical approach to calibration is proposed, based on three main aspects. First, the coupling of two models built on well-validated algorithms, to simulate (1) the irrigation system and the soil water balance in the unsaturated zone and (2) the groundwater flow. Second, the solution of the inverse problem of groundwater hydrology with the comparison model method to calibrate the model. Third, the use of appropriate criteria and cross-checks (comparison of the calibration results and of the model outputs with hydraulic and hydrogeological data) to choose the final parameter sets that warrant the physical coherence of the model. The approach has been tested by application to a large and intensively irrigated alluvial basin in northern Italy. 相似文献
38.
Mauro Giudici Stefano Margiotta Fiorella Mazzone Sergio Negri Chiara Vassena 《Environmental Earth Sciences》2012,67(7):1891-1907
The control exerted by the hydrostratigraphic structure on aquifer recharge, groundwater flow and discharge along the coastal areas of a Mediterranean basin (Salento peninsula, about 5,000?km2 wide, southern Italy) is assessed through the development and application of a groundwater flow model based on the reconstruction of the hydrostratigraphic architecture at the regional scale. The hydrostratigraphic model, obtained by processing surface and subsurface data, is applied to map the top of the main aquifer, which is hosted in the deep hydrostratigraphic unit corresponding to Cretaceous and Oligocene limestones with complex geometrical relationships with the sea. It is also used to estimate the aquifer recharge, which occurs by percolation through overlying younger sediments with low permeability. These data are completed with information about the soil use to estimate water abstraction for irrigation and with literature data to estimate the water abstraction for drinking and industrial purposes. The above-sketched conceptual model is the basis for a finite difference groundwater 2D pseudo-stationary flow model, which assumes the following fundamental approximations: the fractured and karst limestone hydrostratigraphic unit can be approximated, at the model scale, as a continuous medium for which the discrete Darcy??s law is valid; the transition zone between salt and fresh water is so small with respect to the grid spacing that the Ghyben?CHerzberg??s approximation for a sharp interface can be applied. Along the coastline different boundary conditions are assigned if the top of the limestone hydrostratigraphic unit lies either above the sea level (the aquifer has a free surface and fresh water is drained), or below the sea level (the aquifer is under pressure and the contact with sea occurs off-shore). The groundwater flow model correctly predicts the areas where the aquifer is fully saturated with salt water. 相似文献
39.
Silvia Bianchini Francesca Cigna Gaia Righini Chiara Proietti Nicola Casagli 《Environmental Earth Sciences》2012,67(4):1155-1172
Landslide detection and mapping represent fundamental requirements for every hazard and risk evaluation and consequent improvement of the management strategies for such natural hazards. Optical and radar remote sensing can be used to observe landslide-induced ground deformation, ranging from regional to local scales. This work presents a methodology called Landslide HotSpot Mapping; this approach integrates cartographic, thematic and optical data with Persistent Scatterer Interferometry for the identification of extremely slow to very slow moving landslides, and for the evaluation of their state of activity and intensity. This methodology scans wide areas to detect hotspots, which are narrow unstable zones characterized by higher landslide hazard. To these hotspots, priority has to be given when planning field surveys and in situ validation campaigns, so that field work time and effort can be optimized and significantly reduced. The approach is tested in Central Calabria, over a 4,470?km2 area located in southern Italy. ENVISAT ascending images acquired between 2003 and 2009 and processed with the Persistent Scatterer Pairs (PSP) technique are used to analyse deformation patterns. Combining conventional photo-interpretation with the analysis of PSP data, 64 new landslides are identified and the spatial (boundaries) and temporal (activity) information of 980 pre-mapped phenomena (23.6% of updated inventory) are updated. 1,012 active (continuous or reactivated) landslides are identified and 4 hotspot areas selected: San Fili, Rende, Lago, Catanzaro. Urgent field checks have to be organized for these hotspots to validate the satellite-based observations and to design appropriate mitigation measures to reduce impacts on the elements at risk. 相似文献
40.
Accoroni S Romagnoli T Colombo F Pennesi C Di Camillo CG Marini M Battocchi C Ciminiello P Dell'Aversano C Dello Iacovo E Fattorusso E Tartaglione L Penna A Totti C 《Marine pollution bulletin》2011,62(11):2512-2519
Intense blooms of the benthic dinoflagellate Ostreopsis cf. ovata have occurred in the northern Adriatic Sea since 2006. These blooms are associated with noxious effects on human health and with the mortality of benthic organisms because of the production of palytoxin-like compounds. The O. cf. ovata bloom and its relationships with nutrient concentrations at two stations on the Conero Riviera (northern Adriatic Sea) were investigated in the summer of 2009. O. cf. ovata developed from August to November, with the highest abundances in September (1.3 × 106 cells g−1 fw corresponding to 63.8 × 103 cells cm−2). The presence of the single O. cf. ovata genotype was confirmed by a PCR assay. Bloom developed when the seawater temperature was decreasing. Nutrient concentrations did not seem to affect bloom dynamics. Toxin analysis performed by high resolution liquid chromatography-mass spectrometry revealed a high total toxin content (up to 75 pg cell−1), including putative palytoxin and all the ovatoxins known so far. 相似文献