GIS-based GALDIT method for vulnerability assessment to seawater intrusion of the Quaternary coastal Collo aquifer (NE-Algeria)   总被引：1，自引：0，他引：1  

Boulabeiz Mahrez  Stefan Klebingat  Belgacem Houha  Bousnoubra Houria 《Arabian Journal of Geosciences》2018,11(4):71

The overexploitation of groundwater in coastal aquifers is often accompanied by seawater intrusion, intensified by climate change and sea level rise. Heading long-term water quality safety and thus the determination of vulnerable zones to seawater intrusion becomes a significant hydrogeological task for many coastal areas. Due to this background, the present study focussed the established methodology of the GIS-based GALDIT model to assess the aquifer vulnerability to seawater intrusion for the Algerian example of the Quaternary coastal Collo aquifer. According to the result analysis overall, more than half of the total surface of the northern study area can be classified as highly vulnerable. Besides the coastline, the areas nearby the local wadis of Guebli and Cherka occur to be the most vulnerable in the region. In view of further map removal performance as well as single-parameter sensitivity analyses from a coupled perspective respectively the GALDIT parameters, distance from the shore (D) and aquifer hydraulic conductivity (A) have been found to be of key significance regarding the model results (mean effective weightings ~?18–19%). Overall, the study results provide a good approximation basis for future management decisions of the Collo aquifer region, including various perspectives such as identification of suitable settings for prospective groundwater pumping wells.  相似文献   

Saint-Pierre-le-Viger (L5-6) from asteroid 2023 CX1 recovered in the Normandy,France—220 years after the historic fall of L'Aigle (L6 breccia) in the neighborhood     

Addi Bischoff  Markus Patzek  Tommaso Di Rocco  Andreas Pack  Aleksandra Stojic  Jasper Berndt  Stefan Peters 《Meteoritics & planetary science》2023,58(10):1385-1398

On February 13, 2023, a huge fireball was visible over Western Europe (fireball event 2023 CX₁). After the possible strewn field was calculated, the first of several recovered samples, with a mass of about 100 g, was discovered just 2 days after the fireball event on the ground of the village of Saint-Pierre-le-Viger. Meanwhile, more than 60 samples with a total mass of more than 1 kg were recovered and a piece of one of these is studied here. The fall occurred 220 years after the historic meteorite fall of L'Aigle on April 26, 1803, <120 km south. L'Aigle is the closest meteorite fall to Saint-Pierre-le-Viger and belongs to the same chondrite group. Both meteorites are breccias containing only clasts of high metamorphic degree (type 5 and type 6). Since only 20% of the L chondrites are breccias this coincidence is remarkable. As just mentioned, both samples studied from these rocks in this work are ordinary chondrite breccias and consist of equilibrated and recrystallized lithologies of petrologic type 6. The brecciated texture in L'Aigle, resulting in a remarkable light–dark structure, is more pronounced than the brecciated features in Saint-Pierre-le-Viger, from which also type 5 fragments have been reported. The compositions of low-Ca pyroxene and olivine grains in Saint-Pierre-le-Viger (Fs_21.2 and Fa_23.4, respectively) clearly require an L-group classification. L'Aigle was classified as an L6 breccia in the past, and this has now been confirmed by new data on low-Ca pyroxene and olivine (Fs_20.7 and Fa_23.8, respectively). Saint-Pierre-le-Viger contains local thin shock veins, and both meteorites are moderately shocked. Most olivines in the studied samples have planar fractures, but the estimated abundance of mosaicized olivines of 30%–40% among the large grains require a S4 shock classification. Oxygen isotope and bulk chemical data of Saint-Pierre-le-Viger certainly support the L chondrite classification. Bulk spectral data of Saint-Pierre-le-Viger are dominated by silicate minerals, that is, Fe-bearing low-Ca pyroxene, olivine, and plagioclase. Isotopic, chemical, and spectral data of the L'Aigle meteorite are shown for comparison and are very similar, providing additional circumstantial evidence of Saint-Pierre-le-Viger's L chondritic nature.  相似文献   

Synthetic observations using POLARIS: an application to simulations of massive prestellar cores     

Zamponi  Joaquin  Giannetti  Andrea  Bovino  Stefano  Sabatini  Giovanni  Schleicher  Dominik R. G.  K&#;rtgen  Bastian  Reissl  Stefan  Wolf  Sebastian 《Astrophysics and Space Science》2022,367(6):1-9

Astrophysics and Space Science - Dynamical evolution of galaxies is a complex process, especially the centers. Gravitationally coupled gas and stellar discs have been observed to coexist in the...  相似文献   

Economic,institutional and technological uncertainties of emissions trading—a system dynamics modeling approach     

Irina Dolgopolova  Bo Hu  Armin Leopold  Stefan Pickl 《Climatic change》2014,124(3):663-676

System dynamics models are employed for analyzing the impact of different uncertainties on carbon emission trading–both on national and business levels. Economic, institutional and technological uncertainties significantly influence any country's benefits from emission permit trading. If a country participates in trading on the international market then the possible price range becomes the source of additional uncertainty. In the case of business investment decisions for implementing resource‐saving technology, our system dynamics model shows that the first‐mover investor will get significantly fewer advantages than his followers, which leads to delay in primary investment to the sector.  相似文献   

On the relationship between vegetation and climate in tropical and northern Africa     

Martin Schmidt  Doris Klein  Christopher Conrad  Stefan Dech  Heiko Paeth 《Theoretical and Applied Climatology》2014,115(1-2):341-353

Vegetation cover is a crucial component of the Earth’s climate system but, still, our understanding of the mechanisms governing the reciprocal influence between atmosphere and vegetation is limited. In this study, we investigate the unilateral atmospheric impact on vegetation cover in tropical and northern Africa, differentiated into regions with different circulation regimes and into detailed land-cover classes. In contrast to former studies, climate predictors from a regional climate model are used as input for a multiple regression model. Climate models provide consistent data without gaps at high spatial resolution, a considerably larger set of available climate variables and the perspective to transfer the statistical relationships to future projections, e.g., in the context of anthropogenic climate change. Indeed, robust climate predictors which drive up to 70 % of observed interannual vegetation variability could be extracted from the climate model. Besides precipitation and temperature, global radiation, and relative humidity play an important role. The statistical transfer functions are plausible in terms of the affected regions and land-cover classes and draw a rather complex picture of the atmosphere–vegetation relation in Africa.  相似文献   

Effects of hydrophobicity on splash erosion of model soil particles by a single water drop impact     

Sujung Ahn  Stefan H. Doerr  Peter Douglas  Robert Bryant  Christopher A.E. Hamlett  Glen McHale  Michael I. Newton  Neil J. Shirtcliffe 《地球表面变化过程与地形》2013,38(11):1225-1233

Raindrop impact can be a major contributor to particle mobilization for soils and other granular materials. In previous work, water repellent soils, comprised of hydrophobic particles, have been shown to exhibit greater splash erosion losses under multiple drop impact. However, the underlying principle differences in splash behavior between hydrophobic and hydrophilic granular surfaces have not been studied to date. In this study the effects of particle hydrophobicity on splash behaviour by a single water drop impact were examined using high‐speed videography. Water drops (4 mm in diameter) were dropped on beds of hydrophilic and hydrophobic glass beads (sieved range: 350–400 µm), serving as model soil particles. The drop velocity on impact was 2.67 m s^‐1, which corresponds to ~30% of the terminal velocity of a raindrop of similar size. The resulting impact behaviour was measured in terms of the trajectories of particles ejected from the beds and their final resting positions. The response to the impacting water drop was significantly different between hydrophilic and hydrophobic particles in terms of the distance distribution, the median distance travelled by the particles and number of ejected particles. The greater ejection distances of hydrophobic particles were mainly the result of the higher initial velocities rather than differences in ejecting angles. The higher and longer ejection trajectories for hydrophobic particles, compared with hydrophilic particles, indicate that particle hydrophobicity affects splash erosion from the initial stage of rainfall erosion before a water layer may be formed by accumulating drops. The ~10% increase in average splash distance for hydrophobic particles compared with hydrophilic particles suggests that particle hydrophobicity can result in greater net erosion rate, which would be amplified on sloping surfaces, for example, by ridges in ploughed agricultural soils or hillslopes following vegetation loss by clearing or wildfire. Copyright © 2012 John Wiley & Sons, Ltd.  相似文献   

Abiotic schwertmannite transformation kinetics and the role of sorbed As(III)   总被引：1，自引：0，他引：1  

Susanta Paikaray  Stefan Peiffer 《Applied Geochemistry》2012

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Comment on Rosenberg and Garcia: Estimating displacement along the Brenner Fault and orogen-parallel extension in the Eastern Alps, Int J Earth Sci (Geol Rundsch) (2011) 100:1129–1145     

Bernhard Fügenschuh  Neil S. Mancktelow  Stefan S. Schmid 《International Journal of Earth Sciences》2012,101(5):1451-1455

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Historical intensity VIII earthquakes along the Rhone valley (Valais, Switzerland): primary and secondary effects     

Stefan Fritsche  Donat F?h  Gabriela Schwarz-Zanetti 《Swiss Journal of Geoscience》2012,105(1):1-18

In recent years the upper Rhone Valley has been one of the most intensively investigated regions by the Swiss Seismological Service. The high seismicity in the region encourages research in the seismological field and one main focus has been historical seismology. This report presents the state of the art of our historical investigations by giving an overview of the effects of four damaging earthquakes with intensity larger than VII, for which a fairly large number of documents could be found and analyzed. The overview includes the events of 1584 (Aigle, epicentral intensity VIII), 1755 (Brig, epicentral intensity VIII), 1855 (Visp, epicentral intensity VIII), and 1946 (Sierre, epicentral intensity VIII for the main shock and intensity VII for the largest aftershock). The paper focuses mainly on primary and secondary effects in the epicentral region, providing the key data and a general characterization of the event. Generally, primary effects such as the reaction of the population and impact on buildings took more focus in the past. Thus building damage is more frequently described in historic documents. However, we also found a number of sources describing secondary effects such as landslides, snow avalanches, and liquefaction. Since the sources may be useful, we include citations of these documents. The 1584 Aigle event, for example, produced exceptional movements in Lake Geneva, which can be explained by an expanded sub aquatic slide with resultant tsunami and seiche. The strongest of the aftershocks of the 1584 event triggered a destructive landslide covering the villages Corbeyrier and Yvorne, VD. All macroseismic data on the discussed events are accessible through the webpage of the Swiss Seismological Service (http://www.seismo.ethz.ch).  相似文献   

北京市大气可吸入颗粒物的化学成分和来源   总被引：3，自引：0，他引：3  

于扬  岑况  NORRA Stefan  SCHLEICHER Nin  陈媛 《地质通报》2012,31(1):156-163

2007年3月至2008年5月,在北京市成府路东口设立采样点,共采集监测周期为一周的PM2.5(直径小于2.5μm的大气可吸入颗粒物)样品56个,用HR-ICP-MS方法测量了15种元素的含量,并在此基础上应用主因子分析法对PM2.5中这些元素的来源进行探讨。同时,在2008年奥运会和残奥会期间开展了24h时间间隔的密集采样,特别分析了机动车限行期间细颗粒污染物的浓度特征。结果表明,2007年春季至2008年春季期间北京市大气PM2.5平均浓度为72.9μg/m3,超过美国环保局（USEPA）制定的PM2.5年平均浓度限值15μg/m3的近5倍。机动车限行期间北京成府路东口采样点大气PM2.5的平均浓度为40.7μg/m3。通过因子分析方法确定北京PM2.5的3种可能来源：①交通排放、工业排放和燃煤,特征元素为Cu、Zn、As、Sn、Sb、Cd、Pb;②本地扬尘和远源沙尘细颗粒;③可能与成土母岩风化有关的土壤颗粒的再悬浮和/或迁移,其方差贡献率分别为41.2%、31.4%和12.2%。  相似文献