Recent changes in flood risk in the Gran La Plata,Buenos Aires province,Argentina: causes and management strategy     

María Isabel Andrade  Olga Eugenia Scarpati 《GeoJournal》2007,70(4):245-250

The paper analyses the causes of flood occurrence in the Gran La Plata, Buenos Aires Province, Argentina, and the changes that have occurred since the 1970s. The area is characterized by serious deficiencies in the use and management of water resources. The main factors are: (1) flood risk information is not updated; (2) urban building organization does not consider the flood risk; (3) the topography and other physical features are not taken into account in urban development. This research considers some specific problems, especially in data availability, and suggests ways to solve them, including improved analytical methodology. One of the main objectives is to analyse flood risk in social terms, producing a map of flood risk from the “human social vulnerability” point of view. The results suggest that flood risk has increased since the 1980s and that this is associated with changes in precipitation patterns that have also been aggravated by lack of controls on urban development. The poorer areas with the lowest level of infrastructure and public services, many of them developed over the last quarter-century, are especially vulnerable.  相似文献   

Possibilities and specific features of pulsed inductive electromagnetic sounding of shallow sections under complex geological conditions     

A. T. Pavlov  V. P. Lepeshkin  Yu. N. Pavlova 《Izvestiya Physics of the Solid Earth》2007,43(3):251-258

A new high-resolution technology of pulsed induction electrical survey is developed for sounding with small (2–30 m) loops in the depth interval from 0.5 to a few hundred meters (in its possibilities, this technology is unprecedented). The specific feature of the proposed technology is that it is applicable not only to well conducting and contrasting objects but also to sounding of low conductivity and low contrast geological objects (including those overlain by high and low resistivity screens) and to identification of thin and low contrast beds. The minimum initial time of recording the useful signal is 350 ns at a current of 3 A. The accuracy of the location of an interface between layers attains 2–5%. The interpretation results are close to electrical logging data. Testing methodological studies were carried out in the Malo-Batuobinskaya diamondiferous province of the Yakutian permafrost zone and in the inspection of high embankments and two landslides in a railroad zone. The new technology can be used in the presence of intense electromagnetic interferences (in particular, along electrified railroad tracks).  相似文献   

Neural network based daily precipitation generator (NNGEN-P)   总被引：1，自引：0，他引：1  

Jean-Philippe Boulanger  Fernando Martinez  Olga Penalba  Enrique Carlos Segura 《Climate Dynamics》2007,28(2-3):307-324

Daily weather generators are used in many applications and risk analyses. The present paper explores the potential of neural network architectures to design daily weather generator models. Focusing this first paper on precipitation, we design a collection of neural networks (multi-layer perceptrons in the present case), which are trained so as to approximate the empirical cumulative distribution (CDF) function for the occurrence of wet and dry spells and for the precipitation amounts. This approach contributes to correct some of the biases of the usual two-step weather generator models. As compared to a rainfall occurrence Markov model, NNGEN-P represents fairly well the mean and standard deviation of the number of wet days per month, and it significantly improves the simulation of the longest dry and wet periods. Then, we compared NNGEN-P to three parametric distribution functions usually applied to fit rainfall cumulative distribution functions (Gamma, Weibull and double-exponential). A data set of 19 Argentine stations was used. Also, data corresponding to stations in the United States, in Europe and in the Tropics were included to confirm the results. One of the advantages of NNGEN-P is that it is non-parametric. Unlike other parametric function, which adapt to certain types of climate regimes, NNGEN-P is fully adaptive to the observed cumulative distribution functions, which, on some occasions, may present complex shapes. On-going works will soon produce an extended version of NNGEN to temperature and radiation.  相似文献   

The IRI model residual difference and the new method of N(h)-profile determination     

Olga A. Maltseva  O. S. Poltavsky  A. S. Shlyupkin 《Acta Geophysica》2007,55(3):441-458

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Composition and Flux of Holocene Sediments on the Eastern Laptev Sea Shelf, Arctic Siberia     

Henning A. Bauch  Heidemarie Kassens  Olga D. Naidina  Martina Kunz-Pirrung  Jrn Thiede 《Quaternary Research》2001,55(3):344

A 467-cm-long core from the inner shelf of the eastern Laptev Sea provides a depositional history since 9400 cal yr. B.P. The history involves temporal changes in the fluvial runoff as well as postglacial sea-level rise and southward retreat of the coastline. Although the core contains marine fossils back to 8900 cal yr B.P., abundant plant debris in a sandy facies low in the core shows that a river influenced the study site until 8100 cal yr B.P. As sea level rose and the distance to the coast increased, this riverine influence diminished gradually and the sediment type changed, by 7400 cal yr B.P., from sandy silt to clayey silt. Although total sediment input decreased in a step-like fashion from 7600 to 4000 cal yr B.P., this interval had the highest average sedimentation rates and the greatest fluxes in most sedimentary components. While this maximum probably resulted from middle Holocene climate warming, the low input of sand to the site after 7400 cal yr B.P. probably resulted from further southward retreat of the coastline and river mouth. Since about 4000 cal yr B.P., total sediment flux has remained rather constant in this part of the Laptev Sea shelf due to a gradual stabilization of the depositional regime after completion of the Holocene sea-level rise.  相似文献   

Observed precipitation in the Paraná-Plata hydrological basin: long-term trends, extreme conditions and ENSO teleconnections     

Jean-Philippe Boulanger  Julie Leloup  Olga Penalba  Matilde Rusticucci  Florence Lafon  Walter Vargas 《Climate Dynamics》2005,24(4):393-413

The Paraná-Plata basin is the second largest hydrological basin in South America and is of great importance for the countries of the region (Argentina, Bolivia, Brazil, Paraguay and Uruguay). The present study focuses on the long-term trends in basin-scale precipitation with special emphasis on the role of distribution changes in extreme large-scale precipitation events and on the characteristics and evolution of ENSO teleconnections over the last 50 years. First, we defined a Paraná-Plata basin total precipitation index (PTPI) as the precipitations spatially averaged over the hydrological basin. On interannual time scales, such an index is mainly representative of anomalous monsoon precipitations in the northern part of the basin and large convective precipitation anomalies in the center of the basin (Paraguay-southern Brazil-Uruguay-northern Argentina) typical of the canonical ENSO teleconnection pattern. Our major findings clearly highlight a positive trend in yearly averaged PTPI mainly from the late 1960s to the early 1980s with a strong dependence from month-to-month. The largest precipitation increase is observed from November to May in southern Brazil and Argentina. A close examination of PTPI distributions during the two halves of the period 1950–2001 shows that the changes in the mean state from 1950–1975 to 1976–2001 result from significant changes in each calendar month mean state and in the tails of the PTPI anomaly distributions in May with lesser and weaker large-scale dry events and stronger large-scale wet events. Further studies will be needed to assess whether the observed trend in large-scale extreme precipitation conditions can be related to natural climate variability or anthropogenic activities and whether it is associated to changes in local/regional extreme events. The stronger wet conditions in different months seem to be associated to changes in ENSO characteristics (amplitude, propagation, spatial structure, ...) since the 1982–1983 El Niño. Indeed, spatial ENSO teleconnections (stronger in November and April–May) have greatly evolved from 1950–1975 to 1976–2001. Moreover, we demonstrate that there is a strong modulation and displacement of the teleconnection patterns from one event to another, impeding the definition of robust statistical relationship between ENSO and precipitation in the Paraná-Plata basin (except maybe over a very limited area near the common border between Paraguay, Argentina and Brazil). Finally, the non-antisymmetrical patterns of precipitation between El Niño and La Niña conditions and the non-linear relationship between precipitation and either Niño3.4 or Niño1+2 sea surface temperature indices show that linear statistical forecast systems are actually of very limited use for impact predictions on society on a local or regional scale.  相似文献   

Identification of the non-linear behaviour of liquefied and non-liquefied soils during the 1995 Kobe earthquake     

Olga V. Pavlenko  Kojiro Irikura 《Geophysical Journal International》2005,160(2):539-553

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Moscow and St. Petersburg, a sequence of capitals, a tale of two cities     

Olga Gritsai  Herman van der Wusten 《GeoJournal》2000,51(1-2):33-45

From early modern times until the present, Russia (temporarily extended to the USSR) had two capital cities: Moscow and Petersburg. Moscow was the original capital, it was succeeded by Petersburg from the beginning of the 18th century. From the early 20th century onward Moscow again became the capital, but it became a different kind of capital at the end of the 20th century. The paper describes the evolution of the representation of the state function in the appearance of the capital cities by way of the state buildings, the monuments, the street names. In addition it analyses the fate of the former capitals (first Moscow, then Petersburg) in terms of their symbolic functions. Petersburg originated as a capital turned to the outside emphasizing Russia's European vocation, while Moscow was at first the inward looking capital city representing the distinctive spiritual values of Russia. Changes had to do with the changes in the nature of the successive political regimes and with the changing roles of the two cities within those regimes.  相似文献   

Classification of hydrogeological features in volcanic areas of Kamchatka and a characterization of volcanogenic basins     

Yu. F. Manukhin  L. E. Pavlova 《Journal of Volcanology and Seismology》2011,5(3):159-178

Geological-structural and hydrogeological features available in the Kamchatka region were used to identify three leading types of volcanogenic hydrogeological structures: Quaternary volcanogenic basins (VBs), Neogene volcanogenic adbasins (VABs), and artesian volcanogenic basins (AVBs). The first type subdivides into six subtypes by morphogenetic features. It is these subtypes that control the conditions under which the VBs are generated. All these are characterized from the standpoint of regional hydrogeology.  相似文献   

The characteristic photoluminescence and EPR features of superdeep diamonds (São-Luis,Brazil)     

Olga P. Yuryeva  Mariana I. Rakhmanova  Vladimir A. Nadolinny  Dmitry A. Zedgenizov  Vladislav S. Shatsky  Hiroyuki Kagi  Andrey Yu. Komarovskikh 《Physics and Chemistry of Minerals》2015,42(9):707-722

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