The Westerly Index as complementary indicator of the North Atlantic oscillation in explaining drought variability across Europe   总被引：1，自引：0，他引：1  

Sergio M. Vicente-Serrano  Ricardo García-Herrera  David Barriopedro  Cesar Azorin-Molina  Juan I. López-Moreno  Natalia Martín-Hernández  Miquel Tomás-Burguera  Luis Gimeno  Raquel Nieto 《Climate Dynamics》2016,47(3-4):845-863

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Proposal of a New Parameter for the Weathering Characterization of Carbonate Flysch-Like Rock Masses: The Potential Degradation Index (PDI)     

M. Cano  R. Tomás 《Rock Mechanics and Rock Engineering》2016,49(7):2623-2640

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Behavior of Shallow Strip Footing on Twin Voids     

Arash Alimardani Lavasan  Ali Talsaz  Mahmoud Ghazavi  Tom Schanz 《Geotechnical and Geological Engineering》2016,34(6):1791-1805

This paper numerically examines the bearing capacity and failure mechanism of a shallow strip foundation constructed above twin voids. The voids may refer to caves, caverns, underground aqueduct or tunnels due to water seepage, chemical reaction or deliberately excavated in soil deposit. The ability of numerical model to accurately predict the system behavior is evaluated by performing verification analyses on existing researches. Subsequently, a parametric study carried out to reveal the influence of size of footing/voids and their location (i.e. depth, spacing, eccentricity) on the bearing capacity of footing. To clarify the failure mechanism, the distribution of shear strain in the soil for different scenarios is assessed. The parametric study provided a new framework to determine the bearing capacity and the mode of failure for footings on voids. Based on the results, a criterion can be issued to avoid collapse of footing/voids regarding the shape, location and size of voids. The results can also be used to design construction of a footing on existing voids while the acquired failure mechanisms can be appointed to develop analytical solutions for this problem. Results demonstrated that a critical depth for voids and a critical distance between them exist where the influence on the ultimate bearing capacity of footing disappears.  相似文献   

Hyper-resolution mapping of regional storm surge and tide flooding: comparison of static and dynamic models   总被引：1，自引：0，他引：1  

Jorge A. Ramirez  Michal Lichter  Tom J. Coulthard  Chris Skinner 《Natural Hazards》2016,82(1):571-590

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Comparison of water-level,extensometric, DInSAR and simulation data for quantification of subsidence in Murcia City (SE Spain)     

S. Tessitore  J. A. Fernández-Merodo  G. Herrera  R. Tomás  M. Sanabria  J. Duro  J. Mulas  D. Calcaterra 《Hydrogeology Journal》2016,24(3):727-747

Subsidence due to groundwater overexploitation has been recognized in the metropolitan area of Murcia (25 km²) in south-eastern Spain since the early 1990s. Previous published works have focused their attention on land subsidence that occurred during the drought period between 1995 and 2008. This work first analyzes the groundwater recovery that has occurred since 2008 and then determines the kind of associated ground deformation detected by the new extensometric data. Subsequently, subsidence time series are computed on 24 geotechnical boreholes scattered throughout the study area by means of a hydro-mechanical finite element code and a linear-elastic constitutive law. A spatio-temporal interpolation of the numerically modeled surface displacements is performed over the whole domain and compared with extensometers and DInSAR-derived displacement maps in two different periods: the drought period from 2004 to 2008, and the recovery period from 2008 to 2012. In spite of the limited information on the geomechanical parameters characterizing the modelled geological formations, the proposed approach is able to discriminate areas where the soils have an elastic behavior (small differences in the comparisons) or an elasto-plastic behavior (large differences in the comparisons). This zonation enhances the understanding of the subsidence phenomenon in Murcia City and could prevent, from a quantitatively point of view, future severe subsidence due to aquifer overexploitation.  相似文献   

Structural and Functional Composition of Benthic Nematode Assemblages During a Natural Recovery Process of <Emphasis Type="Italic">Zostera noltii</Emphasis> Seagrass Beds     

Patrick Materatski  Anna-Maria Vafeiadou  Tom Moens  Helena Adão 《Estuaries and Coasts》2016,39(5):1478-1490

In 2008, the stable seagrass beds of the Mira estuary (SW Portugal) disappeared completely; however, during 2009, they have begun to present early symptoms of natural recovery, characterised by a strongly heterogeneous distribution. This study was designed to investigate the spatial and temporal variability patterns of species composition, densities and trophic composition of the benthic nematode assemblages in this early recovery process, at two sampling sites with three stations each and at five sampling occasions. Because of the erratic and highly patchy seagrass recovery and the high environmental similarity of the two sampling sites, we expected within-site variability in nematode assemblages to exceed between-site variability. However, contrary to that expectation, whilst nematode genus composition was broadly similar between sites, nematode densities differed significantly between sites, and this between-site variability exceeded within-site variability. This may be linked to differences in the Zostera recovery patterns between both sites. In addition, no clear temporal patterns of nematode density, trophic composition and diversity were evident. Nematode assemblages generally resembled those of other estuarine muddy intertidal areas, which have a high tolerance of stress conditions.  相似文献   

Identification of Uranyl Minerals Using Oxygen K‐Edge X‐Ray Absorption Spectroscopy          下载免费PDF全文

Jesse D. Ward  Mark Bowden  C. Tom Resch  Steven Smith  Bruce K. McNamara  Edgar C. Buck  Gregory C. Eiden  Andrew M. Duffin 《Geostandards and Geoanalytical Research》2016,40(1):135-148

Although most of the world's uranium exists as pitchblende or uraninite, this mineral can be weathered to a great variety of secondary uranium minerals, most containing the uranyl cation. Anthropogenic uranium compounds can also react in the environment, leading to spatial–chemical alterations that could be useful for nuclear forensics analyses. Soft X‐ray absorption spectroscopy (XAS) has the advantages of being non‐destructive, element‐specific and sensitive to electronic and physical structure. The soft X‐ray probe can also be focused to a spot size on the order of tens of nanometres, providing chemical information with high spatial resolution. However, before XAS can be applied at high spatial resolution, it is necessary to find spectroscopic signatures for a variety of uranium compounds in the soft X‐ray spectral region. To that end, we collected the near edge X‐ray absorption fine structure (NEXAFS) spectra of a variety of common uranyl‐bearing minerals, including uranyl carbonates, oxyhydroxides, phosphates and silicates. We find that uranyl compounds can be distinguished by class (carbonate, oxyhydroxide, phosphate or silicate) based on their oxygen K‐edge absorption spectra. This work establishes a database of reference spectra for future spatially resolved analyses. We proceed to show scanning X‐ray transmission microscopy (STXM) data from a schoepite particle in the presence of an unknown contaminant.  相似文献   

Evaluating the impact of visualization of wildfire hazard upon decision-making under uncertainty     

Lisa Cheong  Susanne Bleisch  Allison Kealy  Kevin Tolhurst  Tom Wilkening  Matt Duckham 《International journal of geographical information science》2016,30(7):1377-1404

The paper investigates whether the methods chosen for representing uncertain geographic information aid or impair decision-making in the context of wildfire hazard. Through a series of three human subject experiments, utilizing 180 subjects and employing increasingly difficult tasks, this research evaluates the effect of five different visualizations and a text-based representation on decision-making under uncertainty. Our quantitative experiments focus specifically on the task of decision-making under uncertainty, rather than the task of reading levels of uncertainty from the map. To guard against the potential for generosity and risk seeking in decision-making under uncertainty, the experimental design uses performance-based incentives. The experiments showed that the choice of representation makes little difference to performance in cases where subjects are allowed the time and focus to consider their decisions. However, with the increasing difficulty of time pressure, subjects performed best using a spectral color hue-based representation, rather than more carefully designed cartographic representations. Text-based and simplified boundary encodings were among the worst performers. The results have implications for the performance of decision-making under uncertainty using static maps, especially in the stressful environments surrounding an emergency.  相似文献   

Evaluation of coseismic landslide hazard on the proposed Haast-Hollyford Highway,South Island,New Zealand     

Tom R. Robinson  Tim R. H. Davies  Thomas M. Wilson  Caroline Orchiston  Nicolas Barth 《Georisk: Assessment and Management of Risk for Engineered Systems and Geohazards》2016,10(2):146-163

Coseismic landsliding presents a major hazard to infrastructure in mountains during large earthquakes. This is particularly true for road networks, as historically coseismic landsliding has resulted in road losses larger than those due to ground shaking. Assessing the exposure of current and planned highway links to coseismic landsliding for future earthquake scenarios is therefore vital for disaster risk reduction. This study presents a method to evaluate the exposure of critical infrastructure to landsliding from scenario earthquakes from an underlying quantitative landslide hazard assessment. The method is applied to a proposed new highway link in South Island, New Zealand, for a scenario Alpine Fault earthquake and compared to the current network. Exposure (the likelihood of a network being affected by one or more landslides) is evaluated from a regional-scale coseismic landslide hazard model and assessed on a relative basis from 0 to 1. The results show that the proposed Haast-Hollyford Highway (HHH) would be highly exposed to coseismic landsliding with at least 30–40?km likely to be badly affected (the Simonin Pass route being the worse affected of the two routes). In the current South Island State Highway network, the HHH would be the link most exposed to landsliding and would increase the total network exposure by 50–70% despite increasing the total road length by just 3%. The present work is intended to provide an effective method to assess coseismic landslide hazard of infrastructure in mountains with seismic hazard, and potentially identify mitigation options and critical network segments.  相似文献   

Event water detection in tile drainage runoff using stable isotopes and a water temperature in small agricultural catchment in Bohemian-Moravian Highlands,Czech Republic     

Antonín Zajíček  Tomáš Pomije  Tomáš Kvítek 《Environmental Earth Sciences》2016,75(9):838

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