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671.
A major development programme comprising 15 gas fields of the northern Adriatic Sea has recently been submitted to the Ministry
of the Environment, VIA Committee for the assessment of the environmental impact, by ENI-Agip, the Italian national oil company.
One of the largest reservoirs is Chioggia Mare, located about 10 km offshore of the Venetian littoral, with a burial depth
of 1000–1400 m. The planned gas production from this field is expected to impact the shoreline stability with a potential
threat to the city of Venice, 25 km northwest of the center of Chioggia Mare. To evaluate the risk of anthropogenic land subsidence
due to gas withdrawal, a numerical model was developed that predicts the compaction of both the gas-bearing formations and
the lateral/bottom aquifer (water drive) during a 13-year producing and a 12-year post-production period, and the transference
of the deep compaction to the ground surface. To address the uncertainty of a few important hydromechanical parameters, several
scenarios are simulated and the most pessimistic predictions obtained. The modeling results show that at most 1 cm of land
subsidence over 25 years may be expected at the city of Chioggia, whereas Venice is not subject to settlement. If aquifer
drawdown is mediated by water injection, land subsidence is arrested 5 km offshore, with the Chioggia littoral zone experiencing
a rebound of 0.6–0.7 cm.
Electronic Publication 相似文献
672.
673.
Hazardous industrial sites have always represented a threat for the community often provoking major accidents overcoming the
boundaries of the plants and affecting the surrounding urban areas. If the industrial sites are located in natural hazard-prone
areas, technological accidents may be triggered by natural events, generating so-called na-tech events which may modify and
increase the impact and the overall damage in the areas around them. Nevertheless, natural and technological hazards are still
treated as two separate issues, and up to now the methods for na-tech risk assessment have been developed mainly for specific
natural hazards, generally restricted to some plant typologies and to the area of the plant itself. Based on a review of the
current na-tech literature, this article illustrates a risk assessment method as a supporting tool for land use planning strategies
aimed at reducing na-tech risk in urban areas. More specifically, a multi attribute decision-making method, combined with
fuzzy techniques, has been developed. The method allows planners to take into account, according to different territorial
units, all the individual na-tech risk factors, measured through both quantitative and qualitative parameters, while providing
them with a na-tech risk index, useful to rank the territorial units and to single out the priority intervention areas. The
method is designed to process information generally available about hazardous plants (safety reports), natural hazards (hazard
maps) and features of urban systems mainly influencing their exposure and vulnerability to na-tech events (common statistical
territorial data). Furthermore, the method implemented into a GIS framework should easily provide planners with comparable
maps to figure out the hazard factors and the main territorial features influencing the exposure and vulnerability of urban
systems to na-tech events. The method has been tested on a middle-sized Municipality in the Campania Region, identified as
2nd class seismic zone, according to the Ordinance 3274/2003, in which a LPG storage plant, classified as a plant with major
accident potential by the Seveso II Directive (art. 9), is located just within the city core. 相似文献
674.
Mind the gap: Addressing the shortcomings of marine protected areas through large scale marine spatial planning 总被引:1,自引:0,他引:1
A blind faith in the ability of MPAs to counteract loss of biodiversity is fraught with risk, especially when MPAs are poorly planned and when the consequences of establishing MPAs are not adequately thought out. MPA shortcomings are categorized as one of five main types: (1) MPAs that by virtue of their small size or poor design are ecologically insufficient; (2) inappropriately planned or managed MPAs; (3) MPAs that fail due to the degradation of the unprotected surrounding ecosystems; (4) MPAs that do more harm than good due to displacement and unintended consequences of management; and (5) MPAs that create a dangerous illusion of protection when in fact no protection is occurring. A strategic alternative, which fully utilizes the strengths of the MPA tool while avoiding the pitfalls, can overcome these shortcomings: integrating marine protected area planning in broader marine spatial planning and ocean zoning efforts. 相似文献
675.
The accuracy of several closure models of the Reynolds-Averaged Navier–Stokes Equations in predicting the characteristics of an oscillating turbulent wall boundary layer is analyzed. The analysis involves four low Reynolds number k − ε models and a k − ω model and it is carried out by comparing the model results both with experimental data and with data obtained by a Direct Numerical Simulation (DNS) of the Navier–Stokes equations. The boundary layer is generated by a spatially constant time-oscillating pressure gradient given by the sum of two harmonic components characterized by angular frequencies Ω∗ and 2Ω∗ respectively, which generates a steady streaming because of the asymmetry of turbulence intensity during the cycle. Thus the results are relevant to the boundary layer at the bottom of nonlinear sea waves. The attention is therefore focused on the accuracy of the models in reproducing the period averaged profiles of the hydrodynamic characteristics of the steady streaming. The instantaneous quantities, such as time development of the wall shear stress, profiles of the streamwise velocity, Reynolds stresses and turbulent kinetic energy are also considered and analyzed. The results shows that a model can be judged better or worse than other models depending on the specific flow characteristic under investigation. However, an approach has been adopted which allowed to rank the models according to their accuracy in predicting the values of the hydrodynamic quantities involved in the present study. 相似文献
676.
We present a code for automated detection, classification, and tracking of solar filaments in full-disk Hα images that can contribute to Living With a Star science investigations and space weather forecasting. The program can reliably identify filaments; determine their chirality and other relevant parameters like filament area, length, and average orientation with respect to the equator. It is also capable of tracking the day-by-day evolution of filaments while they travel across the visible disk. The code was tested by analyzing daily Hα images taken at the Big Bear Solar Observatory from mid-2000 until beginning of 2005. It identified and established the chirality of thousands of filaments without human intervention. We compared the results with a list of filament proprieties manually compiled by Pevtsov, Balasubramaniam and Rogers (2003) over the same period of time. The computer list matches Pevtsov's list with a 72% accuracy. The code results confirm the hemispheric chirality rule stating that dextral filaments predominate in the north and sinistral ones predominate in the south. The main difference between the two lists is that the code finds significantly more filaments without an identifiable chirality. This may be due to a tendency of human operators to be biased, thereby assigning a chirality in less clear cases, while the code is totally unbiased. We also have found evidence that filaments obeying the chirality rule tend to be larger and last longer than the ones that do not follow the hemispherical rule. Filaments adhering to the hemispheric rule also tend to be more tilted toward the equator between latitudes 10° and 30°, than the ones that do not. 相似文献
677.
The North Atlantic Oscillation (NAO), which is a dominant circulation pattern in Northern Hemisphere winter, is known to affect sea-level variability in the Mediterranean Sea mainly through the hydrostatic response of water masses to pressure anomalies and changes in evaporation/precipitation budgets. In this study the influence of the NAO on sea levels along the Adriatic coasts is re-assessed in the attempt to uncover the potential causes of the observed high sensitivity of the northern basin to NAO fluctuations. The investigation is focused on the role of the NAO as forcing factor of the winds blowing in the area and of the freshwaters input from the Po River, both of which influence the hydrodynamics of the Northern Adriatic. In addition, some insights into the future of Venice are discussed on the basis of the hypothesis that NAO phases are modulated by the varying solar activity through the intensity of the Earth's geomagnetic activity. 相似文献
678.
Massimiliano De Pasquale Dirk Grupe T. S. Poole A. A. Breeveld S. Zane S. R. Rosen M. J. Page K. O. Mason D. N. Burrows H. A. Krimm N. Gehrels J. A. Nousek P. W. A. Roming S. Kobayashi B. Zhang 《Monthly notices of the Royal Astronomical Society》2006,370(4):1859-1866
We present the results of X-ray and optical observations of GRB 050712 performed by Swift . The X-ray light curve of this burst exhibits episodes of flares in the first 1000 s, the same epoch at which the UVOT detected an optical counterpart. A shallow X-ray decay, with a decay slope of α=−0.73 , followed and lasted ∼70 ks. This behaviour can be explained in terms of activity of the gamma-ray burst 'inner engine', with the possibility that the last flare is caused by the interaction of the ejecta with the surrounding medium.
We also find interesting spectral parameters for the X-ray emission. In particular, data suggest the presence of an intrinsic absorption in the first 1000 s, which can be explained if circumburst medium clouds lie along the line of sight. 相似文献
We also find interesting spectral parameters for the X-ray emission. In particular, data suggest the presence of an intrinsic absorption in the first 1000 s, which can be explained if circumburst medium clouds lie along the line of sight. 相似文献
679.
Apatite fission-track (FT) analyses of sandstone samples collected across the trace of the Ganos segment of the North Anatolian Fault (NAF) in south-western Thrace (Turkey) indicate that a significant structural discontinuity was in existence at least by the latest Oligocene. Such discontinuity had a complex kinematic history, as exhumation south of it occurred during the latest Oligocene and north of it during the mid-Miocene. Our data imply that early Pliocene westward propagation of the NAF in the Marmara region followed a pre-existing structural discontinuity; such discontinuity could be related to the development of the Intra-Pontide Suture, marking the terminal closure of the Intra-Pontide Ocean during the Oligocene. 相似文献
680.
Massimiliano Guzzo Zoran Knežević Andrea Milani 《Celestial Mechanics and Dynamical Astronomy》2002,83(1-4):121-140
We apply the spectral formulation of the Nekhoroshev theorem to investigate the long-term stability of real main belt asteroids. We find numerical indication that some asteroids are in the so-called Nekhoroshev stability regime, that is they are on chaotic orbits but their motion is stable over very long times. We have analyzed the motion of bodies in different regions of the belt, to assess the sensitivity of our method. We found that it allows us to clearly discriminate between different dynamical regimes, such as the one described by the Nekhoroshev stability, the one well described by the KAM theory, and the unstable chaotic regime in which diffusion in phase space can be detected over time spans much shorter than the age of the solar system. 相似文献