Potential Impact of Unconventional Oil Resources on Major Oil-Producing Countries: Scenario Analysis with the ACEGES Model     

Ken’ichi Matsumoto  Vlasios Voudouris 《Natural Resources Research》2015,24(1):107-119

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Hydrological impacts of climate change on a data-scarce Greek catchment     

Venetsanou  P.  Anagnostopoulou  C.  Loukas  A.  Voudouris  K. 《Theoretical and Applied Climatology》2020,140(3):1017-1030

Theoretical and Applied Climatology - This paper demonstrates a climate change impact study on the hydrological process of a data-scarce Greek watershed. The Soil and Water Assessment Tool (SWAT)...  相似文献   

Sedimentation of submarine fan deposits in the Pindos foreland basin,from late Eocene to early Oligocene,west Peloponnesus peninsula,SW Greece     

Panagiotis A. Konstantopoulos  Avraam Zelilidis 《Geological Journal》2013,48(4):335-362

Turbidite facies distribution and palaeocurrent analysis of submarine fan evolution in the Pindos foreland basin of west Peloponnesus peninsula (SW Greece) indicate that this part of the foreland was developed during Late Eocene to Early Oligocene in three linear sub‐basins (Tritea, Hrisovitsi and Finikounda). The basin fill conditions, with a multiple feeder system, which is characterized by axial transport of sediments and asymmetric stratigraphic thickness of the studied sediments, indicate that the Pindos Foreland Basin in this area was an underfilled foreland basin. Sediments are dominated by conglomerates, sandstones and mudstones. The flow types that controlled the depositional processes of the submarine fans were grain flows, debris flows and low‐ and high‐density turbidity currents. The sedimentary model that we propose for the depositional mechanisms and geometrical distribution of the turbidite units in the Tritea sub‐basin is a mixed sand‐mud submarine fan with a sequential interaction of progradation and retrogradation for the submarine fan development and shows a WNW main palaeocurrent direction. The Hrisovitsi sub‐basin turbidite system characterized by small‐scale channels was sediment starved, and the erosion during deposition was greater than the two other studied areas, indicating a more restricted basin topography with a NW main palaeocurrent direction. The Finikounda sub‐basin exhibits sand‐rich submarine fans, is characterized by the presence of distinct, small‐scale, thickening‐upward cycles and by the covering of a distal fan by a proximal fan. It was constructed under the simultaneous interaction of progradation and aggradation, where the main palaeocurrent direction was from NNW to SSE. Copyright © 2012 John Wiley & Sons, Ltd.  相似文献   

Herbage Production and Species Richness in Sub-alpine Grasslands of Different Soil Parent Material in Northern Greece     

MPOKOS J.Panagiotis  YIAKOULAKI D.Maria  PAPAZAFEIRIOU Z.Agapi  SGARDELIS Stefanos  ALIFRAGIS Dimitrios  PAPANIKOLAOU Konstantinos 《山地科学学报》2014,(6):1579-1592

Several abiotic and biotic factors were investigated as possible predictors of local species richness in two sub-alpine grasslands of Jenna and Belles Mountains in Northern Greece.For species richness modelling a hierarchical modelling framework based on generalized additive models was adopted.The two sub-alpine grasslands differed in aspect,altitude and soil parent material（volcanic origin,mostly trachyte,and andesite（TA） for Jenna and metamorphic rocks,mostly gneiss（G） for Belles）.12 fenced squared plots,16 m2 each,were used per grassland,where soil properties,herbage production,species presence and cover of grasses,legumes and forbs were estimated.Mean herbage production was significantly affected by slope and altitude,soil K content and floristic composition as expressed by an ordination axis.Soil p H,floristic composition and average herbage production were significant predictors of forbs and total species richness.For the former,soil N content and for the latter the occurrence of Agrostis capillaris,were also included as significant terms in the predictive model.Thepredictors for grasses species richness were N content,having a positive effect,and average herbage production.In all cases higher species richness was predicted for intermediate values of average herbage production.Differential responses were found between forbs and grasses.The predictors of their species richness were different while for the case of the common predictor（N） the responses of the two groups were also different（grasses species numbers increase and forbs species numbers decreased with increasing N）.Maximum species richness of grasses was observed at relatively low production levels while forbs species richness maximized at relatively high production levels.  相似文献   

Impacts of simultaneous action of drought and overpumping on Quaternary aquifers of Glafkos basin (Patras region, western Greece)   总被引：1，自引：1，他引：1  

N. J. Lambrakis  K. S. Voudouris  L. N. Tiniakos  G. A. Kallergis 《Environmental Geology》1997,29(3-4):209-215

 The Glafkos river basin extends southeast of Patras and is the city's main groundwater reservoir. In the last few years, a steady decline of the groundwater level has been observed in 19 wells due to overpumping and prolonged drought periods. The present paper assesses the adverse simultaneous effects of drought and overpumping on the groundwater regime. Analysis of the rainfall data of the last 60 years shows a decrease of precipitation during the last decade. Runoff measurements show a decrease in the outflow of the Glafkos river. The increased water pumping and the decrease of recharge during the last decades have resulted in depletion of the aquifers. Chemical analyses showed a constant reduction of the groundwater quality. Comparison of piezometric maps of two periods with a 19-year interval shows a clear decline of the general piezometry as a result of overpumping and drought. Received: 11 January 1995 · Accepted: 21 November 1995  相似文献   

A comparative mineralogical study of Te-rich magmatic-hydrothermal systems in northeastern Greece     

P. Voudouris 《Mineralogy and Petrology》2006,87(3-4):241-275

Summary Several magmatic-hydrothermal systems in northeastern Greece (western Thrace and Limnos Island) are highly enriched in tellurides which, in addition to native gold and electrum, represent major carriers of precious metals in the ore. Deposition near the porphyry-epithermal transition for several systems is indicated by field relations and by the presence of key minerals (Pb- and Ag-rich tellurides, Bi-sulfosalts and Bi-tellurides/tellurosulfides). Hessite, stützite, sylvanite, petzite, coloradoite, altaite, unnamed Ag-sulfotelluride, native tellurium and electrum are abundant in intermediate sulfidation quartz-carbonate veins together with zincian tetrahedrite-group minerals, chalcopyrite and galena. The presence of hessite, goldfieldite, native gold and enargite or famatinite suggests deposition at a high sulfidation state. The main stage of telluride deposition took place at ∼275 °C at log fTe₂ values of −8.5 to −7.1 and log fS₂ values of −10.8 to −9.0, based on the Fe-content in sphalerite and the sulfide-telluride mineralogy. The close spatial association of telluride mineralization with intrusive centers of intermediate composition, the base metal enrichment and the trace element signature involving Au, Ag, Te, Bi, Sn and Mo suggest that ore-forming components were introduced at the porphyry-epithermal transition. Potential sources of tellurium are the high-K calc-alkaline (western Thrace) to shoshonitic (Limnos) intrusive rocks.  相似文献   

The grey-green divide: multi-temporal analysis of greenness across 10,000 urban centres derived from the Global Human Settlement Layer (GHSL)     

Christina Corbane  Pesaresi Martino  Politis Panagiotis  Florczyk J. Aneta  Melchiorri Michele  Freire Sergio 《International Journal of Digital Earth》2020,13(1):101-118

ABSTRACT

The presence of green spaces within city centres has been recognized as a valuable component of the city landscape. Vegetation provides a variety of benefits including energy saving, improved air quality, reduced noise pollution, decreased ambient temperature and psychological restoration. Evidence also shows that the amount of vegetation, known as ‘greenness’, in densely populated areas, can also be an indicator of the relative wealth of a neighbourhood. The ‘grey-green divide’, the contrast between built-up areas with a dominant grey colour and green spaces, is taken as a proxy indicator of sustainable management of cities and planning of urban growth. Consistent and continuous assessment of greenness in cities is therefore essential for monitoring progress towards the United Nations Sustainable Development Goal 11. The availability of multi-temporal greenness information from Landsat data archives together with data derived from the city centres database of the Global Human Settlement Layer (GHSL) initiative, offers a unique perspective to quantify and analyse changes in greenness across 10,323 urban centres all around the globe. In this research, we assess differences between greenness within and outside the built-up area for all the urban centres described by the city centres database of the GHSL. We also analyse changes in the amount of green space over time considering changes in the built-up areas in the periods 1990, 2000 and 2014. The results show an overall trend of increased greenness between 1990 and 2014 in most cities. The effect of greening is observed also for most of the 32 world megacities. We conclude that using simple yet effective approaches exploiting open and free global data it is possible to provide quantitative information on the greenness of cities and its changes over time. This information is of direct interest for urban planners and decision-makers to mitigate urban related environmental and social impacts.  相似文献   

Multivariate statistical analysis for the assessment of groundwater quality under different hydrogeological regimes     

N. Kazakis  C. Mattas  A. Pavlou  O. Patrikaki  K. Voudouris 《Environmental Earth Sciences》2017,76(9):349

Multivariate statistical analysis has been widely used for hydrogeochemical characterization of groundwater quality. In this study, hydrochemical data from three hydrological basins were used and two methods (factor and cluster analyses) were applied. The first area is the coastal area of Eastern Thermaikos Gulf where groundwater is influenced by seawater intrusion and geothermal fluids. The other two areas are the inland basins of Gallikos and Perdikas in which agricultural and industrial activities constitute the main anthropogenic pollution sources of groundwater. Initially, the aforementioned methods were applied for each area separately and resulted in a different number of significant factors and clusters, while the natural and anthropogenic influences were spatially determined in each area. Additionally, factor and cluster analyses were applied coupling data from all areas. Therefore, five clusters and three major factors were determined distinguishing the hydrochemical processes and impacts from anthropogenic activities in more detail. It is worth mentioning that the application of cluster analysis in the coupled groundwater samples of all studied areas resulted beneficially in the most hydrochemically complex area. Salinization dominates in the coastal area, while in Gallikos and Perdikas basins high concentrations of NO₃ occur mainly due to agricultural activities and small livestock units. The numerous hydrochemical samples are identified as the main issue for the higher discretization and reliability of the second approach. Nevertheless, this study is associated with a number of limitations of multivariable statistical analysis regarding extreme concentrations of Cl and Na. This issue stimulates further research in overcoming and understanding these drawbacks.  相似文献   

Structural identification of Egnatia Odos bridges based on ambient and earthquake induced vibrations     

Evaggelos Ntotsios  Christos Karakostas  Vasilios Lekidis  Panagiotis Panetsos  Ioannis Nikolaou  Costas Papadimitriou  Thomas Salonikos 《Bulletin of Earthquake Engineering》2009,7(2):485-501

The dynamic characteristics of two representative R/C bridges on Egnatia Odos motorway in Greece are estimated based on low amplitude ambient and earthquake-induced vibrations. The present work outlines the instrumentation details, algorithms for computing modal characteristics (modal frequencies, damping ratios and modeshapes), modal-based finite element model (FEM) updating methods for estimating structural parameters, and numerical results for the modal and structural dynamic characteristics of the two bridges based on ambient and earthquake induced vibrations. Transverse, bending and longitudinal modes are reliably identified and stiffness-related properties of the piers, deck and elastomeric bearings of the FEMs of the two bridges are estimated. Results provide qualitative and quantitative information on the dynamic behavior of the bridge systems and their components under low-amplitude vibrations. Modeling assumptions are discussed based on the differences in the characteristics identified from ambient and earthquake vibration measurements. The sources of the differences observed between the identified modal and structural characteristics of the bridges and those predicted by FEMs used for design are investigated and properly justified.  相似文献   

Bridge health monitoring system based on vibration measurements     

Evaggelos Ntotsios  Costas Papadimitriou  Panagiotis Panetsos  Grigorios Karaiskos  Kyriakos Perros  Philip C. Perdikaris 《Bulletin of Earthquake Engineering》2009,7(2):469-483

A bridge health monitoring system is presented based on vibration measurements collected from a network of acceleration sensors. Sophisticated structural identification methods, combining information from the sensor network with the theoretical information built into a finite element model for simulating bridge behavior, are incorporated into the system in order to monitor structural condition, track structural changes and identify the location, type and extent of damage. This work starts with a brief overview of the modal and model identification algorithms and software incorporated into the monitoring system and then presents details on a Bayesian inference framework for the identification of the location and the severity of damage using measured modal characteristics. The methodology for damage detection combines the information contained in a set of measurement modal data with the information provided by a family of competitive, parameterized, finite element model classes simulating plausible damage scenarios in the structure. The effectiveness of the damage detection algorithm is demonstrated and validated using simulated modal data from an instrumented R/C bridge of the Egnatia Odos motorway, as well as using experimental vibration data from a laboratory small-scaled bridge section.  相似文献