Coastal vulnerability to wave storms of Sele littoral plain (southern Italy)   总被引：1，自引：1，他引：0  

Gianluigi Di Paola  Pietro Patrizio Ciro Aucelli  Guido Benassai  Germán Rodríguez 《Natural Hazards》2014,71(3):1795-1819

This paper presents a new method for coastal vulnerability assessment (CVA), which relies upon three indicators: run-up distance (as a measurement of coastal inundation), beach retreat (as a measurement of potential erosion), and beach erosion rate (obtained through the shoreline positions in different periods). The coastal vulnerability analysis of Sele Coastal Plain to storm impacts is examined along a number of beach profiles realized between 2008 and 2009. This particular study area has been selected due to its low-lying topography and high erosion propensity. Results are given in terms of an impact index, performed by combining the response due to coastal inundation, storm erosion, and beach erosion rate. This analysis is implemented on the basis of morphosedimentary characteristics of the beach, wave climate evaluation, and examination of multitemporal aerial photographs and topographic maps. The analysis of the final results evidences different coastal responses as a function of the beach width and slope, which in turn depend on the local anthropization level. The comparison of this method with a Coastal Vulnerability Index method evidences the better attitude of CVA index to take into account the different beach features to explain the experienced damages in specific stretches of the coastline considered.  相似文献   

The reconstruction of a glacial lake outburst flood using HEC-RAS and its significance for future hazard assessments: an example from Lake 513 in the Cordillera Blanca,Peru   总被引：1，自引：0，他引：1  

Jan Klimeš  Miroslava Benešová  Vít Vilímek  Petr Bouška  Alejo Cochachin Rapre 《Natural Hazards》2014,71(3):1617-1638

In April 2010, an ice/rockfall into Lake 513 triggered a glacial lake outburst flood (GLOF) along the Chucchun River in the Cordillera Blanca of Peru. This paper reconstructs the hydrological characteristics of this as yet undocumented event using a 1D flood model prepared with HEC-RAS. The principle model inputs were obtained during detailed field surveys of surface characteristics and topography within the river and across the adjacent floodplain; a total of 120 cross-sections were surveyed. These inputs were refined further by eyewitness accounts and additional geomorphological observations. The flood modelling has enabled us to constrain the extent of the water surface and its elevation at each cross-section in addition to defining the peak discharge (580 m³ s^?1). These modelling results show good agreement with other information about the flood including: flood marks and minimum flood levels; the lake displacement wave height; the extent of the flooded area; and the travel time from Lake 513 to the confluence with the Santa River. This demonstrates that the model offers a reliable reconstruction of the basic hydrological characteristics of the GLOF. It provides important information about the flood intensity and significantly improves our ability to model future flood scenarios along both the studied river and within neighbouring catchments. The flood hazard, defined by the flood depth during peak discharge, shows that the majority of the damaged infrastructure (houses, bridges, and a drinking water treatment plant) was only subjected to low or medium flood intensities (defined by a maximum water depth of less than 2 m). These low flood intensities help to explain why the flooding caused comparatively minor damage despite the significant public attention it attracted.  相似文献   

An Elasto-Plastic Constitutive Model for Rock Joints Under Cyclic Loading and Constant Normal Stiffness Conditions   总被引：1，自引：1，他引：0  

Jan Nemcik  Ali Mirzaghorbanali  Naj Aziz 《Geotechnical and Geological Engineering》2014,32(2):321-335

An elasto-plastic constitutive model is introduced for rock joints under cyclic loading, considering the additional shear resistance generated by the asperity damage in the first forward shear cycle and sliding mechanism for further shearing. A series of cyclic loading direct shear tests was conducted on artificial joints with triangular asperities and replicas of a real rock asperity surface under constant normal stiffness (CNS) conditions. The model was calibrated and then validated using selected data sets from the experimental results. Model simulations were found to be in good agreement with the rock joints behaviour under cyclic loading and CNS conditions both in stress prediction and dilation behaviour. In addition, dynamic stability analysis of an underground structure was carried out, using Universal Distinct Element Code and the proposed constitutive model.  相似文献   

Integral transformations of gradiometric data onto a GRACE type of observable     

Michal Šprlák  Pavel Novák 《Journal of Geodesy》2014,88(4):377-390

Integral transformations of gravitational gradients onto a Gravity Recovery And Climate Experiment (GRACE) type of observable are derived in this article. The gravitational gradients represent components of the gravitational tensor in the local north-oriented frame. The GRACE type of observable corresponds to a difference between two gravitational vectors as projected onto the line of sight between the two GRACE satellites. In total, three integral transformations relating vertical–vertical, vertical–horizontal and horizontal–horizontal gravitational gradients with the GRACE type of observable are provided. Spectral and closed forms of corresponding isotropic kernels are derived for each transformation. Special cases show that the integral transformations are general and relate gravitational gradients to many other quantities of the gravitational field, such as the gravitational vector, and its radial and tangential components. Correctness of the mathematical derivations is validated in a closed-loop simulation using synthetic data.  相似文献   

Molecular gas in young planetary nebulae     

R. Bachiller  V. Bujarrabal  J. Martín-Pintado  R. Planesas  J. Gómez-González 《Astrophysics and Space Science》1990,171(1-2):195-198

We review our recent results concerning the molecular gas content of young planetary nebulae NGC 2346, M 2–9, and NGC 6720 (the Ring Nebula in Lyra).Paper presented at the 11th European Regional Astronomical Meetings of the IAU on New Windows to the Universe, held 3–8 July, 1989, Tenerife, Canary Islands, Spain.  相似文献   

Direct detection of the secondary spectrum of the interacting eclipsing binary TX UMa     

J. Grygar  L. Hřič  R. Komžík  Z. Šíma 《Astrophysics and Space Science》1991,185(2):189-193

Eclipsing binary TX UMa was observed with the D.A.O. high-dispersion spectrographs in 1969–1970, with emphasis on the detailed coverage of the primary minimum. One spectrum was taken exclusively within totality, thus exhibiting an uncontaminated spectrum of the secondary component. This leads to spectral reclassification of the secondary (F6 IV). The narrowing of the line profile of the H-line in totality is interpreted in terms of synchronous rotation of the secondary (v sini80 km s^–1) while the primary rotates faster (v sini130 km s^–1) than synchronously (v sini50 km s^–1). Although the secondary does not fill in its Roche lobe fully, the system exhibits pronounced indications of rather strong physical interaction. This is now supported also by the profound changes of the line profiles of the H-line with phase.  相似文献   

Are the oroclines of the Variscan belt related to late Variscan strike‐slip tectonics?     

José R. Martínez Catalán 《地学学报》2011,23(4):241-247

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Compositional variations in ferrotapiolite + tantalite pairs from the beryl-columbite pegmatite at Moravanynad Váhom, Slovakia     

M. Novák  P. Uher  P. Černý  P. Siman 《Mineralogy and Petrology》2000,69(3-4):295-306

Summary ?Three texturally and compositionally distinct pairs of ferrotapiolite + tantalite, all spatially related to a cleavelandite unit, were distinguished in the zoned beryl-columbite pegmatite at Moravany nad Váhom, Považsky Inovec Mts., Slovakia. (1) Inclusions of ferrotapiolite I (∼200 μm) in zoned ferrotantalite I exhibit crosscutting tielines of coexisting compositions in the columbite-tantalite quadrilateral. (2) Large ferrotapiolite II grains and adjacent, compositionaly variable grains of ferro- to manganotantalite II (∼100 μm) display remarkably diverse tielines, not yet observed in a single sample or locality. (3) Sn-depleted and slightly Mn,Ta-enriched narrow rims (∼20 μm) of ferrotapiolite III with small inclusions of manganotantalite III (≤ 5 μm) are located along a late, hydrothermal, fracture-filling microlite vein cross-cutting ferrotapiolite II. Changes in fO₂ derived from calculated Fe₂O₃ as well as variations in Ti, Sn, W concentrations through the ferrotapiolite + tantalite pairs I to III are negligible. Consequently, it seems plausible to explain the broadening of the two-phase field and the enrichment of ferrotapiolite and tantalite in Mn and Ta particularly by decreasing temperature. A disequilibrium crystallization from highly evolved residual melt and/or fluids is suggested for all textural types.

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Zusammenfassung ?Zusammensetzung von Ferrotapiolit-Tantalit-Paaren im Beryll-Columbit Pegmatit von Moravany nad Váhom (Považsky Inovec Mts., Slowakei) Drei Ferrotapiolit-Tantalit-Paare k?nnen in dem zonierten Beryll-Columbit-Pagmatit von Moravany nad Váhom, Povazsky Inovec Mts., Slowakei, auf der Basis detaillierter textureller und chemischer Untersuchungen unterschieden werden. Sie wurden in verschiedenen Stadien der Pegmatit-Kristallisation gebildet und sind r?mlich in Beziehung zu der Cleavelandit-Einheit (1). Einschlüsse von Ferrotapiolit I (∼200 μm) in zoniertem Ferrotantalit I zeigen sich kreuzende Konoden im Columbit-Tantalit Quadrilateral, die koexistierende K?rner beider Minerale miteinander verbinden. Dies legt nahe, dass Ferrotapiolit ein Produkt prim?rer (magmatischer) Disequilibrium-Kristallisation ist, und gleichzeitig mit den assoziierten Mineralen der Columbit-Gruppe gebildet wurde (2). Gro?e Ferrotapiolit II K?rner und K?rner von angrenzenden Ferro- bis Manganotantalit II (∼100 μm) zeigen Konoden mit bemerkenswerter Verschiedenheit, die bisher nicht in einer einzigen Probe beobachtet wurden. Eine sehr betonte Disequilibrium-Kristallisation aus stark fraktionierter Restschmelze dürfte hierfür verantwortlich sein (3). An Zinn verarmte und etwas an Mn, Ta angereicherter Ferrotapiolit III bildet dünne R?nder (∼20 μm) mit schmalen Einschlüssen von Manganotantalit III (≤5 μm) l?ngs einer Mikrolit-Ader. Erhat sich w?hrend hydrothermaler Subsolidus Verdr?ngung von Ferrotapiolit II durch Sprünge füllenden Microlit gebildet. Schwankungen in fO₂, berechnet aus Fe₂O₃ und die Gehalten an Ti, Sn und W k?nnen in den Ferrotapiolit-Tantalit-Paaren (1) bis (3) vernachl?ssigt werden. Dementsprechend erscheint es naheliegend, die Erweiterung des Zweiphasenfeldes und die Anreicherung von Ferrotapiolit und Tantalit an Mn und Ta durch Temperaturabnahme zu erkl?ren.

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Received May 4, 1999;/revised version accepted January 5, 2000  相似文献   

Groundwater geochemistry of the Chihuahua City region in the Rio Conchos Basin (northern Mexico) and implications for water resources management     

Jürgen Mahlknecht  Axel Horst  Gabriela Hernández-Limón  Ramon Aravena 《水文研究》2008,22(24):4736-4751

The Chihuahua City region, located in the semiarid-arid northern highlands of Mexico, has experienced intensive groundwater abstraction during the last 40 years to meet water demands in the region. A geochemical survey was carried out to investigate the evolution from baseline to modern conditions of a 130-km flow path including the El Sauz–Chihuahua–Aldama–San Diego de Alcalá regions. The research approach included the use of major chemical elements, chlorofluorocarbons and environmental isotope (¹⁸O, ²H, ¹³C and ¹⁴C) tracers. Stable isotopes indicate that groundwater evolves from the evaporation of local rainfall and surface water. Groundwater located at the lower end of the flow section is up to 6000 years old and older groundwater in the order of 9000 years BP was found in a deep well located in the upper part of the flow system, implying contribution from a neighbour basin. The background groundwater chemistry upstream of Chihuahua City results from feldspar weathering. Beyond Chihuahua City the chemical conditions are strongly modified owing to disposal of sewage from public and industrial water supplies into the Rio Chuviscar, subsequent allocation of this water to agricultural irrigation areas and direct infiltration under the river bed. As a consequence, anions like chloride and sulphate are mainly related to surface sources. Nitrate is controlled in part by sewage from public supply and industry and in part by agricultural practices. Arsenic and fluoride are related to weathering of rock formations of local mineralized ranges and subsequent enrichment of the basin-fill by magmatic processes. The results of this study have implications for groundwater management in an arid region that depends entirely on groundwater for domestic, industrial and agricultural water consumption. Copyright © 2008 John Wiley & Sons, Ltd.  相似文献   

Boreas is heading for Denmark…new editors and new address from January 1, 2000     

Professor Jan A. Piotrowski  Eiliv Larsen 《Boreas: An International Journal of Quaternary Research》1999,28(4):435-435

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