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1.
Modelling surface runoff to evaluate the effects of wildfires in multiple semi‐arid,shrubland‐dominated catchments 
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下载免费PDF全文 Wildfires change the infiltration properties of soil, reduce the amount of interception and result in increased runoff. A wildfire at Northeast Attica, Central Greece, in August 2009, destroyed approximately one third of a study area consisting of a mixture of shrublands, pastures and pines. The present study simultaneously models multiple semi‐arid, shrubland‐dominated Mediterranean catchments and assesses the hydrological response (mean annual and monthly runoff and runoff coefficients) during the first few years following wildfires. A physically based, hydrological model (MIKE SHE) was chosen. Calibration and validation results of mean monthly discharge presented very good agreement with the observed data for the pre‐wildfire and post‐wildfire period for two subcatchments (Nash–Sutcliffe Efficiency coefficient of 79.7%). The model was then used to assess the pre‐wildfire and post‐wildfire runoff responses for each of seven catchments in the study area. Mean annual surface runoff increased for the first year and after the second year following the wildfires increased by 112% and 166%, respectively. These values are within the range observed in similar cases of monitored sites. This modelling approach may provide a way of prioritizing catchment selection with respect to post‐fire remediation activities. Additionally, this modelling assessment methodology would be valuable to other semi‐arid areas because it provides an important means for comprehensively assessing post‐wildfire response over large regions and therefore attempts to address some of the scaled issues in the specific literature field of research. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
2.
Hamdan Hamdan Nikos Andronikidis George Kritikakis Nikos Economou Zacharias Agioutantis Paul Schilizzi Chrysanthos Steiakakis Christodoulos Papageorgiou Panagiotis Tsourlos George Vargemezis Antonis Vafidis 《Environmental Earth Sciences》2014,72(5):1589-1598
In this paper, the application of 2D and 3D electrical resistivity methods in geotechnical investigations is explored through a case study in Northern Greece. These two methods were employed at a lignite surface mining operation where fracture zones and discontinuities have been recently observed close to the pit boundaries. The main aim of the geophysical survey was to estimate the inclination of the contact between the Neogene and Schist/Carbonate formations near the southern limits of the pit, as well as to estimate the thickness of the carbonate rocks on top of the Schist formations to evaluate the stability of the southern slopes. Synthetic data were initially generated to help plan an efficient electrical tomography survey, in a region with complex geology and irregular terrain. Three configurations (Wenner–Schlumberger and dipole–dipole or pole–dipole) proved essential in such conditions and helped improving the resolution of the resistivity section. The sections were then calibrated by boreholes. Finally, the geophysical survey provided invaluable data regarding the geometry of the bedrock and possible faults, which was essential for the slope stability calculations. 相似文献
3.
Achilleas Tripolitsiotis Chrysanthos Steiakakis Eirini Papadaki Zacharias Agioutantis Stelios Mertikas Panagiotis Partsinevelos 《Central European Journal of Geosciences》2014,6(1):56-66
This paper explores the potential of using satellite radar inteferometry to monitor time-varying land movement prior to any visible tension crack signs. The idea was developed during dedicated geotechnical studies at a large open-pit lignite mine, where large slope movements (10–20 mm/day) were monitored and large fissures were observed in the immediate area outside the current pit limits. In this work, differential interferometry (DInSAR), using Synthetic Aperture Radar (SAR) ALOS images, was applied to monitor the progression of land movement that could potentially thwart mine operations. Early signs of land movements were captured by this technique well before their visual observation. Moreover, a qualitative comparison of DInSAR and ground geodetic measurements indicates that the technique can be used for the identification of high risk areas and, subsequently, for the optimization of the spatial distribution of the available ground monitoring equipment. Finally, quantitative land movement results from DInSAR are shown to be in accordance with simultaneous measurements obtained by ground means. 相似文献
4.
Stimulated Raman scattering is used to prepare ensembles of aligned acetylene molecules in thev
2=1 excited vibrational level. Decay and transfer of the alignment is followed by laser induced fluorescence. Measurements of the initially excited alignment agree well with theoretical calculations. The rate constants for decay decrease as the rotational quantum numberJ of the excited level increases. 相似文献
5.
Changes in storm track and cyclone activity in three SRES ensemble experiments with the ECHAM5/MPI-OM1 GCM 总被引：2，自引：1，他引：2
J. G. Pinto U. Ulbrich G. C. Leckebusch T. Spangehl M. Reyers S. Zacharias 《Climate Dynamics》2007,29(2-3):195-210
Synoptic activity over the Northern Hemisphere is evaluated in ensembles of ECHAM5/MPI-OM1 simulations for recent climate
conditions (20C) and for three climate scenarios (following SRES A1B, A2, B1). A close agreement is found between the simulations
for present day climate and the respective results from reanalysis. Significant changes in the winter mid-tropospheric storm
tracks are detected in all three scenario simulations. Ensemble mean climate signals are rather similar, with particularly
large activity increases downstream of the Atlantic storm track over Western Europe. The magnitude of this signal is largely
dependent on the imposed change in forcing. However, differences between individual ensemble members may be large. With respect
to the surface cyclones, the scenario runs produce a reduction in cyclonic track density over the mid-latitudes, even in the
areas with increasing mid-tropospheric activity. The largest decrease in track densities occurs at subtropical latitudes,
e.g., over the Mediterranean Basin. An increase of cyclone intensities is detected for limited areas (e.g., near Great Britain
and Aleutian Isles) for the A1B and A2 experiments. The changes in synoptic activity are associated with alterations of the
Northern Hemisphere circulation and background conditions (blocking frequencies, jet stream). The North Atlantic Oscillation
index also shows increased values with enhanced forcing. With respect to the effects of changing synoptic activity, the regional
change in cyclone intensities is accompanied by alterations of the extreme surface winds, with increasing values over Great
Britain, North and Baltic Seas, as well as the areas with vanishing sea ice, and decreases over much of the subtropics. 相似文献
6.
The purpose of this work is to provide an OSL dating framework for raised marine sequences in the South-West coast of Greece during Upper Quaternary. Paleontological investigations and Geographic Information System (GIS) analysis on elevated marine landforms have proved that a record of uplift and eustacy exists in South Greece since the Early Pleistocene (～1.6 Ma). Hereby, we test the suitability of the SAR methodology for recuperated-OSL (Re-OSL), proposed by Wang et al. (2007), on coarse-grained quartz aliquots from emerged nearshore outcrops. Protocol's performance is examined on the basis of signal characteristics, dose response, sensitivity changes, recovery of known doses and Re-OSL bleachability to sunlight. The accuracy of the Re-OSL dates calculated for natural samples is also discussed. 相似文献
7.
Areti Gianni Miltiadis Zamparas Ioannis T. Papadas George Kehayias Yiannis Deligiannakis Ierotheos Zacharias 《Aquatic Geochemistry》2013,19(1):77-95
The balance between physicochemical processes, influencing vertical and temporal distributions of metal compounds in one relatively isolated anoxic environment, constitutes the objective of the present work. Ion activity product (IAP) was calculated for manganese and iron sulfides, in order to define the metal sulfide forms that control Fe and Mn solubility in the bottom waters of anoxic lagoons. Iron solubility depended on amorphous FeS formation, while manganese sulfides were a minor component in a solid solution lowering its solid-phase activity. A theoretical physicochemical model was developed for the iron speciation, based on experimental pH and redox potential data. A very good match was achieved for the measured and the theoretical total dissolved iron, at all depths. The dominance of oxidant iron species Fe(OH) 3 ? in the surface waters and their sequence by FeSH+ and FeSaq in the deeper layers brings out the influence of physicochemical parameters (dissolved oxygen, sulfide, pH and Eh) in vertical distribution of dissolved metal species, in anoxic/hypoxic basins. Based on these findings, we can conclude that the distribution of manganese and iron is of special interest, not only because these are the indicators of redox conditions but also for the role of their oxidized/reduced forms in the formation of the biogeochemical structure of redox zone. 相似文献
8.
Joaquim G. Pinto Stefan Zacharias Andreas H. Fink Gregor C. Leckebusch Uwe Ulbrich 《Climate Dynamics》2009,32(5):739-737
The occurrence of extreme cyclones is analysed in terms of their relationship to the NAO phase and the dominating environmental
variables controlling their intensification. These are latent energy (equivalent potential temperature 850 hPa is used as
an indicator), upper-air baroclinicity, horizontal divergence and jet stream strength. Cyclones over the North Atlantic are
identified and tracked using a numerical algorithm, permitting a detailed analysis of their life cycles. Extreme cyclones
are selected as the 10% most severe in terms of intensity. Investigations focus on the main strengthening phase of each cyclone.
The environmental factors are related to the NAO, which affects the location and orientation of the cyclone tracks, thus explaining
why extreme cyclones occur more (less) frequently during strong positive (negative) NAO phases. The enhanced number of extreme
cyclones in positive NAO phases can be explained by the larger area with suitable growth conditions, which is better aligned
with the cyclone tracks and is associated with increased cyclone life time and intensity. Moreover, strong intensification
of cyclones is frequently linked to the occurrence of extreme values of growth factors in the immediate vicinity of the cyclone
centre. Similar results are found for ECHAM5/OM1 for present day conditions, demonstrating that relationships between the
environment factors and cyclones are also valid in the GCM. For future climate conditions (following the SRES A1B scenario),
the results are similar, but a small increase of the frequency of extreme values is detected near the cyclone cores. On the
other hand, total cyclone numbers decrease by 10% over the North Atlantic. An exception is the region near the British Isles,
which features increased track density and intensity of extreme cyclones irrespective of the NAO phase. These changes are
associated with an intensified jet stream close to Europe. Moreover, an enhanced frequency of explosive developments over
the British Isles is found, leading to more frequent windstorms affecting Europe.
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| Joaquim G. PintoEmail: |
9.
Ilias Bertahas Elias Dimitriou Ioannis Karaouzas Sofia Laschou Ierotheos Zacharias 《洁净——土壤、空气、水》2006,34(4):349-359
Trichonis Lake is the largest natural freshwater body in Greece with a surface area of 97 km2. It receives pollutants from numerous anthropogenic activities, especially from intensive agricultural practices, urban sewages, stock grazing land and small industries. In this study, hydrologic and chemical parameters are assessed during two periods (1990–1991) and (2001–2002) to evaluate the effects of the climatic changes on phosphorous trends and consequently on the trophic status of Trichonis Lake. Even though large quantities of fertilizers are applied in the lake's catchment, phosphorus loads are still in the permissible level as estimated according to Vollenweider's relationship based on total phosphorus concentration. Due to relatively higher rainfall precipitation during the last years, an increased amount of the phosphorus entering into the lake system is flushed out, thus keeping the trophic status of the lake in oligotrophic levels. In contrast, lower rainfall rates during the first period (1990–1991) have led to the decrease in phosphorus flush out and its detainment into the lake water and sediment resulting to mesotrophic conditions. As the trophic status of the lake is mainly hydrologically dependent and thus unpredictable, effective management plans targeting the elimination of nutrient pollution loadings are necessary. 相似文献
10.
Christos Makris Panagiota Galiatsatou Konstantia Tolika Christina Anagnostopoulou Katerina Kombiadou Panayotis Prinos Kondylia Velikou Zacharias Kapelonis Elina Tragou Yannis Androulidakis Gerasimos Athanassoulis Christos Vagenas Ioannis Tegoulias Vassilis Baltikas Yannis Krestenitis Theodoros Gerostathis Kostantinos Belibassakis Eugen Rusu 《Ocean Dynamics》2016,66(12):1603-1635