Circalittoral Macrobenthic Assemblages of Strymonikos Gulf (North Aegean Sea)   总被引：1，自引：0，他引：1  

Costas G.  Dounas Athanasios S.  Koukouras 《Marine Ecology》1992,13(2):85-99

Abstract. Six macrobenthic assemblages of the circalittoral zone found in Strymonikos Gulf, North Aegean Sea, are described and compared with the corresponding ones from other Mediterranean and Atlantic areas. For the delimination of these assemblages and the evaluation of the major environmental gradients governing their distribution, several numerical techniques were used.  相似文献   

Relationships of photosynthetically active radiation and shortwave irradiance     

G. Papaioannou  N. Papanikolaou  D. Retalis 《Theoretical and Applied Climatology》1993,48(1):23-27

Summary Hourly measurements of solar irradiance in the wave band excluding photosynthetically active radiation (PAR) and solar irradiance (SI) were made over a 12-month period at the National Observatory of Athens, for obtaining the ratios of PAR to SI. These irradiance ratios exhibit dependence on sky conditions, with slightly larger values being observed under cloudy skies and seasonal variations, attributable to changes in local air mass climatology. The highest values have been obtained during the growing season (April–September). The mean annual value of 0.473 observed for the irradiance ratio in the PAR band compares favorably with values reported in the literature for different locations over a wide geographical area.With 2 Figures  相似文献   

A new approach for the development and management of brackish karst springs     

Athanasios Maramathas 《Hydrogeology Journal》2006,14(7):1360-1366

A new approach to the method of artificial upraising of the water outlet point, for management and development of brackish karst springs, uses the MODKARST model. Brackish karst springs simulation can be used to estimate the necessary upraising of the spring elevation, so that sea-water intrusion is blocked. The consequent freshwater loss to the sea, due to this upraising, can also be estimated. The method has been applied to the periodically brackish karst Almiros spring at Heraklion of Crete, Greece. The spring simulation showed that the sea-water intrusion could be prevented through an artificial upraising of the water-outlet point, realized by the construction of a dam. The exact upraising has been estimated. Freshwater loss to the sea because of this upraising has also been estimated. The model could also be used as a tool for the management of the spring. For example, it was used to assess management options for the spring during the depletion period of the year 1994. The best scenario for the development of the spring during this period has been estimated.  相似文献   

Manifestation and measurement of the fractal characteristics of karst hydrogeological formations     

Athanasios J. Maramathas  Andreas G. Boudouvis 《Advances in water resources》2006

A new method of estimating the fractal dimension of the percolation backbone of karst systems, which are discharged through karst springs, is presented. This method is based on the simulation of the spring by the MODKARST deterministic mathematical model. Application has been made to the Psiloritis karst formation in Crete, which feeds the periodically brackish karst spring “Almiros” in Crete. Furthermore, the estimated dimension justifies an independently determined power law that quantifies the sea intrusion into the karst system.  相似文献   

On the Analysis of the Complex Forbush Decreases of January 2005     

A. Papaioannou  O. Malandraki  A. Belov  R. Skoug  H. Mavromichalaki  E. Eroshenko  A. Abunin  S. Lepri 《Solar physics》2010,266(1):181-193

In this work an analysis of a series of complex cosmic ray events that occurred between 17 January 2005 and 23 January 2005 using solar, interplanetary and ground based cosmic ray data is being performed. The investigated period was characterized both by significant galactic cosmic ray (GCR) and solar cosmic ray (SCR) variations with highlighted cases such as the noticeable series of Forbush effects (FEs) from 17 January 2005 to 20 January 2005, the Forbush decrease (FD) on 21 January 2005 and the ground level enhancement (GLE) of the cosmic ray counter measurements on 20 January 2005. The analysis is focusing on the aforementioned FE cases, with special attention drawn on the 21 January 2005, FD event, which demonstrated several exceptional features testifying its uniqueness. Data from the ACE spacecraft, together with GOES X-ray recordings and LASCO CME coronagraph images were used in conjunction to the ground based recordings of the Worldwide Neutron Monitor Network, the interplanetary data of OMNI database and the geomagnetic activity manifestations denoted by K _p and D _st indices. More than that, cosmic ray characteristics as density, anisotropy and density gradients were also calculated. The results illustrate the state of the interplanetary space that cosmic rays crossed and their corresponding modulation with respect to the multiple extreme solar events of this period. In addition, the western location of the 21 January 2005 solar source indicates a new cosmic ray feature, which connects the position of the solar source to the cosmic ray anisotropy variations. In the future, this feature could serve as an indicator of the solar source and can prove to be a valuable asset, especially when satellite data are unavailable.  相似文献   

Worst case scenario as stakeholder decision support: a 5- to 6-m sea level rise in the Rhone delta, France     

Marc Poumadère  Claire Mays  Gabriela Pfeifle  Athanasios T. Vafeidis 《Climatic change》2008,91(1-2):123-143

Risk policy and public attitudes appear disconnected from research predicting warmer climate partially due to human activity. To step out of this stalled situation, a worst case scenario of a 5- to 6-m sea level rise (SLR) induced by the collapse of the WAIS and occurring during the period 2030–2130 is constructed and applied to the Rhone delta. Physical and socio-economic scenarios developed with data from the Rhone delta context are developed and submitted to stakeholders for a day-long workshop. Group process analysis shows a high level of trust and cooperation mobilized to face the 5–6 m SLR issue, despite potentially diverging interests. Two sets of recommendations stem from the scenario workshop. A conservative “wait and see” option is decided when the risk of the WAIS collapse is announced in 2030. After WAIS collapse generates an effective 1 m SLR rise by 2050, decisions are taken for total retreat and rendering of the Rhone delta to its hydrological function. The transposition of these results into present-day policy decisions could be considered. The methodology developed here could be applied to other risk objects and situations, and serve for policy exercises and crisis prevention.  相似文献   

Regionalisation of population growth projections in coastal exposure analysis     

Jan-Ludolf Merkens  Daniel Lincke  Jochen Hinkel  Sally Brown  Athanasios Thomas Vafeidis 《Climatic change》2018,151(3-4):413-426

Large-area coastal exposure and impact analysis has focussed on using sea-level rise (SLR) scenarios and has placed little emphasis on socioeconomic scenarios, while neglecting spatial variations of population dynamics. We use the Dynamic Interactive Vulnerability Assessment (DIVA) Framework to assess the population exposed to 1 in 100-year coastal flood events under different population scenarios, that are consistent with the shared socioeconomic pathways (SSPs); and different SLR scenarios, derived from the representative concentration pathways (RCPs); and analyse the effect of accounting for regionalised population dynamics on population exposure until 2100. In a reference approach, we use homogeneous population growth on national level. In the regionalisation approaches, we test existing spatially explicit projections that also account for urbanisation, coastal migration and urban sprawl. Our results show that projected global exposure in 2100 ranges from 100 million to 260 million, depending on the combination of SLR and population scenarios and method used for regionalising the population projections. The assessed exposure based on the regionalised approaches is higher than that derived from the reference approach by up to 60 million people (39%). Accounting for urbanisation and coastal migration leads to an increase in exposure, whereas considering urban sprawl leads to lower exposure. Differences between the reference and the regionalised approaches increase with higher SLR. The regionalised approaches show highest exposure under SSP5 over most of the twenty-first century, although total population in SSP5 is the second lowest overall. All methods project the largest absolute growth in exposure for Asia and relative growth for Africa.  相似文献   

Colume Contents 1999     

Nagy El-Bermawi  Athanasios D. Baxevanis  Theodore J. Abatzopoulos  Gilbert Van Stappen  Patrick Sorgeloos 《International Journal of Salt Lake Research》1999,8(4):397-399

  相似文献   

Learning soil parameters and updating geotechnical reliability estimates under spatial variability – theory and application to shallow foundations     

Iason Papaioannou  Daniel Straub 《Georisk: Assessment and Management of Risk for Engineered Systems and Geohazards》2017,11(1):116-128

ABSTRACT

Field data is commonly used to determine soil parameters for geotechnical analysis. Bayesian analysis allows combining field data with other information on soil parameters in a consistent manner. We show that the spatial variability of the soil properties and the associated measurements can be captured through two different modelling approaches. In the first approach, a single random variable (RV) represents the soil property within the area of interest, while the second approach models the spatial variability explicitly with a random field (RF). We apply the Bayesian concept exemplarily to the reliability assessment of a shallow foundation in a silty soil with spatially variable data. We show that the simpler RV approach is applicable in cases where the measurements do not influence the correlation structure of the soil property at the vicinity of the foundation. In other cases, it is expected to underestimate the reliability, and a RF model is required to obtain accurate results.  相似文献   

The SHARE European Earthquake Catalogue (SHEEC) 1000–1899     

M. Stucchi  A. Rovida  A. A. Gomez Capera  P. Alexandre  T. Camelbeeck  M. B. Demircioglu  P. Gasperini  V. Kouskouna  R. M. W. Musson  M. Radulian  K. Sesetyan  S. Vilanova  D. Baumont  H. Bungum  D. Fäh  W. Lenhardt  K. Makropoulos  J. M. Martinez Solares  O. Scotti  M. Živčić  P. Albini  J. Batllo  C. Papaioannou  R. Tatevossian  M. Locati  C. Meletti  D. Viganò  D. Giardini 《Journal of Seismology》2013,17(2):523-544

In the frame of the European Commission project “Seismic Hazard Harmonization in Europe” (SHARE), aiming at harmonizing seismic hazard at a European scale, the compilation of a homogeneous, European parametric earthquake catalogue was planned. The goal was to be achieved by considering the most updated historical dataset and assessing homogenous magnitudes, with support from several institutions. This paper describes the SHARE European Earthquake Catalogue (SHEEC), which covers the time window 1000–1899. It strongly relies on the experience of the European Commission project “Network of Research Infrastructures for European Seismology” (NERIES), a module of which was dedicated to create the European “Archive of Historical Earthquake Data” (AHEAD) and to establish methodologies to homogenously derive earthquake parameters from macroseismic data. AHEAD has supplied the final earthquake list, obtained after sorting duplications out and eliminating many fake events; in addition, it supplied the most updated historical dataset. Macroseismic data points (MDPs) provided by AHEAD have been processed with updated, repeatable procedures, regionally calibrated against a set of recent, instrumental earthquakes, to obtain earthquake parameters. From the same data, a set of epicentral intensity-to-magnitude relations has been derived, with the aim of providing another set of homogeneous Mw estimates. Then, a strategy focussed on maximizing the homogeneity of the final epicentral location and Mw, has been adopted. Special care has been devoted also to supply location and Mw uncertainty. The paper focuses on the procedure adopted for the compilation of SHEEC and briefly comments on the achieved results.  相似文献