The relation between karst spring discharge and rainfall by cross-correlation analysis (Campania, southern Italy)   总被引：4，自引：2，他引：2  

Francesco Fiorillo  Angelo Doglioni 《Hydrogeology Journal》2010,18(8):1881-1895

The relation between rainfall and the discharge from two springs, located at the base of different karst massifs in southern Italy, is investigated by cross-correlation analyses. Data are derived from a continuous time window of 13 years. The input signal involves multiple rainfall time series (cumulative rainfall over varying time windows), while the time series of daily spring discharges are used as the output signal. Analyses were first conducted on the unprocessed data and then on data for which linear trends and seasonal components had been removed, the latter by a spectral analysis. Analyses contributed to the investigation of the time required for water to flow through the karst aquifers at the two sites. Long time intervals of the cumulative rainfall (>60 days) appear to be the main component affecting the spring discharge hydrographs; shorter time intervals seem to be related to quick-flow paths. Some statistics about the linear regression and the meaning of the cross-correlation analysis are discussed. Cross-correlation analysis can provide strong support for identification of the main rainfall contribution and the travel time through the main infiltration pathways in aquifers.  相似文献   

Water quality and relationship between superficial and ground water in Rome (Aniene River basin,central Italy)   总被引：1，自引：1，他引：0  

Francesco La Vigna  Simone Ciadamidaro  Roberto Mazza  Laura Mancini 《Environmental Earth Sciences》2010,60(6):1267-1279

Chemical, physical, and biological features of streams and ground water of the North-Eastern area of Rome are jointly analyzed in order to assess the status of water resources. Ground water was investigated with classical survey methods (pH, temperature, and electric conductivity). Microbiological pollution, faunal composition, and stream surrounding area conditions of surface waters were studied, in order to quantify the residual value of these ecosystems from both a human and an environmental point of view. Results show a general impairment of the system and the comparison between superficial waters and shallow ground waters makes it possible to detect the presence of a connection between the two levels. This relationship occurs as an exchange from superficial waters (streams and rivers) to the shallow aquifers. Where superficial waters are contaminated, as in the Tor Sapienza stream, pollutants move to the shallow aquifers too, due to the decreased pressure of the over-exploited aquifer. Moreover, uncontrolled drilling activity, diffused in urban areas, makes it possible the connection between shallow and deep ground water. Notwithstanding this, the mixing between superficial and deep ground water system in Rome is not very widespread and, apparently, limited to restricted areas.  相似文献   

A numerical Round Robin on tunnels under seismic actions   总被引：3，自引：0，他引：3  

Emilio Bilotta  Giovanni Lanzano  S. P. Gopal Madabhushi  Francesco Silvestri 《Acta Geotechnica》2014,9(4):563-579

Although the seismic behaviour of shallow circular tunnels in soft ground is generally safer than aboveground structures, some tunnels were recently damaged during earthquakes. In some cases, damage was associated with strong ground shaking and site amplification, which increased the stress level in the tunnel lining. Pseudo-static and simplified dynamic analyses enable to assess transient changes in internal forces during shaking. Nevertheless, experimental evidences of permanent changes in internal loads in the tunnel lining would suggest that a full dynamic analysis including plastic soil behaviour should be performed when modelling the dynamic interaction between the tunnel and the ground. While sophisticated numerical methods can be used to predict seismic internal forces on tunnel structures during earthquakes, the accuracy of their predictions should be validated against field measurements, but the latter are seldom available. A series of centrifuge tests were therefore carried out at the University of Cambridge (UK) on tunnel models in sand, in the framework of a research project funded by the Italian Civil Protection Department. A numerical Round Robin on Tunnel Tests was later promoted among some research groups to predict the observed behaviour by means of numerical modelling. In this paper, the main results of five selected numerical predictions are summarized and compared with the experimental results.  相似文献   

Thermal decay of carbonate dimension stones: fabric,physical and mechanical changes     

Gioacchino Francesco Andriani  Luigi Germinario 《Environmental Earth Sciences》2014,72(7):2523-2539

This paper deals with the effects of thermal stresses on selected carbonate rocks used as dimension stones. They are Mesozoic calcareous and dolomitic rocks cropping out in Apulia (southern Italy) that, for their physico-mechanical and aesthetic properties, have always been finding a large application both as ornamental stones and as simple construction materials; their use is attested not only in Italy, in works of archaeological, historical and artistic interest too. The cause–effect relationships of thermal degradation were studied by means of an artificial accelerated ageing test, in order to provide a perspective about the decay of carbonate stones due to diurnal and seasonal temperature fluctuations, as well as thermal shocks during events of fire development. The stone samples were subjected to thermal cycles in a muffle furnace, ranging from 100 to 700 °C; after each cycle, several non-destructive and semi-destructive tests were carried out: mass and volume measurements, mercury intrusion porosimetry, sclerometer tests, ultrasonic tests, thin-section observations and determination of chromatic alterations through image analysis and Munsell charts method. In this way, the qualitative and quantitative modifications induced in fabric, physical and mechanical properties were discussed. The results highlight the fundamental role of depositional and diagenetic fabric that, together with mineralogical composition, represents the most significant discriminating factor in the response of the stone to thermal stresses.  相似文献   

Geometry and Properties of the Excavation-Induced Fractures at the Meuse/Haute-Marne URL Drifts   总被引：1，自引：1，他引：0  

G. Armand  F. Leveau  C. Nussbaum  R. de La Vaissiere  A. Noiret  D. Jaeggi  P. Landrein  C. Righini 《Rock Mechanics and Rock Engineering》2014,47(1):21-41

The performance and safety assessment and technology demonstration are the main objectives of research programs for feasibility studies for deep geological repository of radioactive waste. In this context, the French national radioactive waste management agency (ANDRA) started to develop the Meuse/Haute-Marne underground research laboratory (URL) at Bure, nearly 300 km East of Paris. The host formation consists of a Callovo-Oxfordian claystone found between 420 and 550 m below ground, overlain and underlain by poorly permeable carbonate formations. One of the major concerns related to performance assessment is the excavation-induced fractures which may provide groundwater preferential pathway for radionuclide migration. The extent of the fractures possibly acting significantly in the radionuclide migration is known as the excavation damaged zone (EDZ). A scientific study on the EDZ characterization is performed at the main level of the URL (?490 m). Observations such as structural analysis on core, overcored resin-filled samples, geological survey of the drift face and sidewalls, were made to better understand the fracture network characteristics, extent and its generation. Pulse and constant head test hydraulic conductivity measurements were performed with multi packer system to estimate the extension of the EDZ hydraulic conductivity. Fractures exhibited high transmissivity near the excavation walls, but farther from the exaction walls, shear fractures showed hydraulic conductivity values reflecting values of undisturbed or slightly disturbed rock mass condition. The major findings in terms of geometry and properties of excavation-induced fractures are discussed in detail in this paper. For example, it is observed that the shape of the fracture network depends on the orientation of the drift in relation to the orientation of the in situ stress field.  相似文献   

Monitoring large oil slick dynamics with moderate resolution multispectral satellite data     

Pieralberto Maianti  Marco Rusmini  Riccardo Tortini  Giorgio Dalla Via  Federico Frassy  Andrea Marchesi  Francesco Rota Nodari  Marco Gianinetto 《Natural Hazards》2014,73(2):473-492

Accidental release of crude oil into the sea due to human activity causes water pollution and heavy damages to natural ecosystems killing birds, fish, mammals and other organisms. A number of monitoring systems are used for tracking the spills and their effects on the marine environment, as well as for collecting data for feeding models. Among them, Earth observation technologies play a crucial role and moderate spatial resolution satellite systems are able to collect images with a very short revisit time or even daily. This paper describes the use of Moderate-Resolution Imaging Spectroradiometer data for monitoring large oil slicks with the fluorescence/emissivity index and object-based image analysis. Two case studies are presented: the Deepwater Horizon (2010) and the Campos Basin (2011) oil spill accidents. Results show that it is possible to track the dynamics of the slick both for massive and long-lasting accidents and for smaller and very quick accidents. The main advantages of the method proposed are a straightforward implementation, a fast and semi-automated data processing and the capability of integration of daytime and nighttime acquisitions, as well as its adaptability to different sensors.  相似文献   

Lessons learned from two case histories of seismic microzonation in Italy     

Filippo Santucci de Magistris  Anna d’Onofrio  Augusto Penna  Rodolfo Puglia  Francesco Silvestri 《Natural Hazards》2014,74(3):2005-2035

The prediction of the variability of the seismic ground motion in a given built-up area is considered an effective tool to plan appropriate urban development, to undertake actions on seismic risk mitigation and to understand the damage pattern caused by a strong-motion event. The procedures for studying the seismic response and the seismic microzonation of an urban area are well established; nevertheless, some controversial points still exists and are discussed here. In this paper, the selection of a reference input motion, the construction of a subsoil model and the seismic response analysis procedures are discussed in detail, based on the authors’ experience in two Italian case histories: the seismic microzonation of the city of Benevento, which was a predictive study, and the simulation of seismic response and damage distribution in the village of San Giuliano di Puglia, which was a retrospective analysis.  相似文献   

JP3D compression of solar data-cubes: Photospheric imaging and spectropolarimetry     

Dario Del Moro  Luca Giovannelli  Ermanno Pietropaolo  Francesco Berrilli 《Experimental Astronomy》2017,43(1):23-37

Hyperspectral imaging is an ubiquitous technique in solar physics observations and the recent advances in solar instrumentation enabled us to acquire and record data at an unprecedented rate. The huge amount of data which will be archived in the upcoming solar observatories press us to compress the data in order to reduce the storage space and transfer times. The correlation present over all dimensions, spatial, temporal and spectral, of solar data-sets suggests the use of a 3D base wavelet decomposition, to achieve higher compression rates. In this work, we evaluate the performance of the recent JPEG2000 Part 10 standard, known as JP3D, for the lossless compression of several types of solar data-cubes. We explore the differences in: a) The compressibility of broad-band or narrow-band time-sequence; I or V Stokes profiles in spectropolarimetric data-sets; b) Compressing data in [x,y, λ] packages at different times or data in [x,y,t] packages of different wavelength; c) Compressing a single large data-cube or several smaller data-cubes; d) Compressing data which is under-sampled or super-sampled with respect to the diffraction cut-off.  相似文献   

Lithosphere density model in Italy: no hint for slab pull     

Enrico Brandmayr  Iginio Marson  Fabio Romanelli  Giuliano Francesco Panza 《地学学报》2011,23(5):292-299

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Seasonal rainfall–runoff relationships in a lowland forested watershed in the southeastern USA     

Ileana B. La Torre Torres  Devendra M. Amatya  Timothy J. Callahan 《水文研究》2011,25(13):2032-2045

Hydrological processes of lowland watersheds of the southern USA are not well understood compared to a hilly landscape due to their unique topography, soil compositions, and climate. This study describes the seasonal relationships between rainfall patterns and runoff (sum of storm flow and base flow) using 13 years (1964–1976) of rainfall and stream flow data for a low‐gradient, third‐order forested watershed. It was hypothesized that runoff–rainfall ratios (R/P) are smaller during the dry periods (summer and fall) and greater during the wet periods (winter and spring). We found a large seasonal variability in event R/P potentially due to differences in forest evapotranspiration that affected seasonal soil moisture conditions. Linear regression analysis results revealed a significant relationship between rainfall and runoff for wet (r² = 0·68; p < 0·01) and dry (r² = 0·19; p = 0·02) periods. Rainfall‐runoff relationships based on a 5‐day antecedent precipitation index (API) showed significant (r² = 0·39; p < 0·01) correspondence for wet but not (r² = 0·02; p = 0·56) for dry conditions. The same was true for rainfall‐runoff relationships based on 30‐day API (r² = 0·39; p < 0·01 for wet and r² = 0·00; p = 0·79 for dry). Stepwise regression analyses suggested that runoff was controlled mainly by rainfall amount and initial soil moisture conditions as represented by the initial flow rate of a storm event. Mean event R/P were higher for the wet period (R/P = 0·33), and the wet antecedent soil moisture condition based on 5‐day (R/P = 0·25) and 30‐day (R/P = 0·26) prior API than those for the dry period conditions. This study suggests that soil water status, i.e. antecedent soil moisture and groundwater table level, is important besides the rainfall to seasonal runoff generation in the coastal plain region with shallow soil argillic horizons. Copyright © 2011 John Wiley & Sons, Ltd.  相似文献