Fog harvesting: An alternative source of water supply on the West Coast of South Africa   总被引：1，自引：0，他引：1  

Jana Olivier 《GeoJournal》2004,61(2):203-214

Experiments conducted during the 1990s investigated the feasibility of using fog water to supplement existing water supplies in the arid west coast region of South Africa. Based on these results, a project was initiated aimed at implementing an operational fog water collection system to provide potable water to a small, water-poor rural community. A 70 m² fog water collector was subsequently erected on the crest of the hill located next to the mission station called Lepelfontein. The volume of water collected was measured by means of a water flow meter and a tipping bucket. An automatic weather station recorded rainfall, wind speed and direction. The data record spans the period September 1999–August 2001. This paper gives a brief overview of the methods used to select the experimental site and describes the design of the fog water collection system. This is followed by a detailed account of the water yields, the contribution of fog and rainfall to the total yield, the characteristics of wet events, the factors associated with water collection and water quality. On average, yields of around 4.6 l of water were collected per square metre of collecting surface per day with maximum daily yields approaching 4000 l. The quality of the water was excellent. It thus appears that fog water collection may have considerable potential as an alternative water source at many other locations on the west coast of South Africa. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

The deficient T waves of tsunami earthquakes   总被引：4，自引：0，他引：4  

Emile A. Okal  Pierre-Jean Alasset  Olivier Hyvernaud  François Schindelé 《Geophysical Journal International》2003,152(2):416-432

  相似文献   

The role of physical-biological coupling in the benthic boundary layer under megatidal conditions: The case of the dominant species of theAbra alba community in the Eastern Baie de Seine (English Channel)     

Frédéric Olivier  Christian Retière 《Estuaries and Coasts》1998,21(4):571-584

Recent evidence has shown that postlarvae and juveniles of the most dominant species of theAbra alba community of the eastern Baie de Seine are able to re-enter the water column after larval settlement and undergo active and/or passive redistribution. However, few subtidal studies have been conducted to investigate and quantify the processes controlling the abundance of drifting postlarvae and juveniles. The purpose of this study was to verify the reproducibility or the variability of this phenomenon and to assess coupling between the intensity of drifting and that of bed shear stress, which is dependent on tidal currents, wave characteristics, and sediment features. This study was conducted in June and July 1995 at two sites in the bay, one located at the center of the muddy fine-sediment community and the other at its external border with the fine clean sands of theOphelia borealis community. At each site, suprabenthic sledge samples were taken during specific tidal conditions (low tide, slack water, and flood and ebb peaks) during a neap and a spring tide. Physical data (current velocity, turbidity, and suspended matter content) and meiobenthic samples were taken at the same time. Under megatidal conditions, drifting was a quantitatively important dispersal mechanism for at least 15 of the fine-sediment dominant species belonging to various groups such as polychaetes, molluscs (gastropods and bivalves), and echinoderms. The fluctuation in abundance of drifters was related to tidal range, tidal period, location of the site, and the recruitment dynamics. However, species differed strongly in theri response to hydrodynamical parameters. Three types of drifting species were observed: species that were only present in the water column (‘undet. cardiids’ and Mytilidae); species that were both drifting and present at the seaded (Abra alba, Phaxas pellucidus, Eteone picta, Mysella bidentata, Ophiura texturata, Owenia fusiformis, Pholoe minuta, Phyllodoce lineata, Pectinaria koreni, andSpisula subtruncata); species that were present at the seabed but did not drift during the sampling period (Acrocnida brachiata, Eteone longa, Eumida sanguinea, Glycinde normanni, Magelona mirabilis, Nemertean sp1,Nephtys sp.,Spiophanes bombyx, andTubulanus polymorphus). Each drifting pattern is related to eco-ethological species characteristics and may have very different consequences on population dynamics.  相似文献   

Determination of cirrus radiative parameters from combination between active and passive remote sensing measurements during FRENCH/DIRAC 2001     

Grard Brogniez  Frdric Parol  Laurianne Bcu  Jacques Pelon  Olivier Jourdan  Jean-Franois Gayet  Frdrique Auriol  Christian Verwaerde  Jean-Yves Balois  Bahaiddin Damiri 《Atmospheric Research》2004,72(1-4):425

In the context of the next AQUA Train satellite experiment, airborne measurements were carried out to simulate satellite measurements. They were conducted between September 25 and October 12, 2001, off the coast of southern France over the Atlantic Ocean and over the Mediterranean Sea, respectively. During the intensive Field Radiation Experiment on Natural Cirrus and High-level clouds (FRENCH/DIRAC 2001), natural ice clouds were sampled from in situ and remote sensing measurements. On October 5 and 7, 2001, cirrus cloud decks were described by a complete data set acquired by: (i) in situ microphysical instruments onboard the TBM-700 aircraft: PMS probe, and Polar Nephelometer (ii) and downward-looking radiative instruments onboard the Mystère 20 aircraft: an infrared radiometer, a lidar, a visible imager with polarisation capabilities, and a middle infrared radiometer. Moreover, classical thermodynamical measurements were carried out onboard the Mystère 20. Mean microphysical characteristics of cirrus deck are derived from interpretation of remote sensing measurements. These properties are compared with those derived from in situ microphysical measurements in order to evaluate the radiative impact of natural cirrus clouds.  相似文献   

Late Palaeozoic NE–SW ductile–brittle extension in the La Serre horst,eastern France     

Guilhem Coromina  Olivier Fabbri 《Comptes Rendus Geoscience》2004,336(1):75-84

In the La Serre horst of the Alpine foreland, the pre-Triassic La Serre median fault zone separates a Late Devonian–Early Carboniferous granite from an ignimbrite of unknown age and from Permian deposits. Motion along this fault zone took place first in ductile conditions and then evolved in brittle conditions. Both ductile and brittle shear criteria indicate a top-NE normal-dextral displacement. Similar motions are reported along faults bounding Late Palaeozoic intramontane coal basins located in the Massif Central and correspond to a widespread NE–SW Late to Post-Orogenic extension that affected the Variscan basement during Late Carboniferous to Early Permian times. To cite this article: G. Coromina, O. Fabbri, C. R. Geoscience 336 (2004).  相似文献   

Seasonal thermal signatures of heat transfer by water exchange in an underground vault     

Frédéric Perrier  Pierre Morat  Toshio Yoshino  Osam Sano  Hisashi Utada  Olivier Gensane  Jean-Louis Le Mouël 《Geophysical Journal International》2004,158(1):372-384

  相似文献   

Graphitization in a high-pressure,low-temperature metamorphic gradient: a Raman microspectroscopy and HRTEM study   总被引：6，自引：0，他引：6  

Olivier Beyssac  Jean-Noël Rouzaud  Bruno Goffé  Fabrice Brunet  Christian Chopin 《Contributions to Mineralogy and Petrology》2002,143(1):19-31

The graphitization of carbonaceous material (CM) in a high-pressure metamorphic gradient is characterized along a cross section in the Schistes Lustrés formation, Western Alps. Along this 25-km cross section, both the CM precursor and the host-rock lithology are homogeneous, and the prograde evolution of the pressure-temperature metamorphic conditions from the lower blueschist-facies (13 kbar, 330 °C) to the eclogite-facies (20 kbar, 500 °C) is tightly constrained by literature data. Raman microspectroscopy shows that at the micrometre scale, this process is progressive and continuous with increasing metamorphic grade, and that the structure of CM is very sensitive to temperature variations. At the nanometre scale (HRTEM), the CM is composed of a mixture of a microporous phase and an onion-ring like phase, both known as non-graphitizing under the effect of temperature at ambient pressure. The HP-LT graphitization produces structurally and microtexturally heterogeneous CM. With increasing metamorphic grade, the graphitization of the two types of CM proceeds up to the triperiodic graphite stage because of microtextural and structural changes that are specific to each type of CM. The microporous material is progressively transformed into graphite through a macroporous transitional stage. In this case, graphitization mainly occurs on the pore walls as a result of pore growth. In the case of concentric onion-ring like material, graphitization occurs in the regions with the largest radius of curvature, i.e. on the outer part of the ring. In comparison with 1-bar experiments, pressure seems to induce microtextural changes, which allows the subsequent structural modifications of the starting material.  相似文献   

Display-sites selection by houbara bustard (Chlamydotis [undulata] macqueenii) in Mori, Xinjiang, People''s Republic of China     

Weikang Yang  Jianfang Qiao  Olivier Combreau  Xingyi Gao  Wenqin Zhong 《Journal of Arid Environments》2002,51(4):625

Display-site selection by houbara bustards was studied in Mori, Xinjiang, China during the breeding seasons from April to June 2000. Most of the habitats chosen for displaying were short sub-shrubby and open areas close to high shrub patches. The displaying males clearly prefer low covered areas and avoid densely covered and high vegetation sites. The vegetation density and number of plant species at display sites were significantly lower from that at randomly selected sites. The average distance to the closest shrub patch was significantly shorter at display sites than at random sites. Plant species richness, vegetative density, vegetative cover and distance to the shrub patches are possibly the most important factors that determined the display-sites selection of houbara bustard.  相似文献   

Origin of Pyroxenite-Peridotite Veined Mantle by Refertilization Reactions: Evidence from the Ronda Peridotite (Southern Spain)   总被引：4，自引：0，他引：4  

Bodinier  Jean-Louis; Garrido  Carlos J.; Chanefo  Ingrid; Bruguier  Olivier; Gervilla  Fernando 《Journal of Petrology》2008,49(5):999-1025

The Ronda orogenic peridotite (southern Spain) contains a varietyof pyroxene-rich rocks ranging from high-pressure garnet granulitesand pyroxenites to low-pressure plagioclase–spinel websterites.The ‘asthenospherized’ part of the Ronda peridotitecontains abundant layered websterites (‘group C’pyroxenites), without significant deformation, that occur asswarms of layers showing gradual modal transitions towards theirhost peridotites. Previous studies have suggested that theselayered pyroxenites formed by the replacement of refractoryspinel peridotites. Here, we present a major- and trace-element,and numerical modelling study of a layered outcrop of groupC pyroxenite near the locality of Tolox aimed at constrainingthe origin of these pyroxenites after host peridotites by pervasivepyroxene-producing, refertilization melt–rock reactions.Mg-number [= Mg/(Mg + Fe) cationic ratio] numerical modellingshows that decreasing Mg-number with increasing pyroxene proportion,characteristic of Ronda group C pyroxenites, can be accountedfor by a melt-consuming reaction resulting in the formationof mildly evolved, relatively low Mg-number melts (0·65)provided that the melt fraction during reaction and the time-integratedmelt/rock ratio are high enough (>0·1 and > 1,respectively) to balance Mg–Fe buffering by peridotiteminerals. This implies strong melt focusing caused by melt channellingin high-porosity domains resulting from compaction processesin a partial melted lithospheric domain below a solidus isothermrepresented by the Ronda peridotite recrystallization front.The chondrite-normalized rare earth element (REE) patterns ofgroup C whole-rocks and clinopyroxenes are convex-upward. Numericalmodeling of REE variations in clinopyroxene produced by a pyroxene-forming,melt-consuming reaction results in curved trajectories in the(Ce/Nd)_N vs (Sm/Yb)_N diagram (where N indicates chondrite normalized).Based on (Ce/Nd)_N values, two transient, enriched domains betweenthe light REE (LREE)-depleted composition of the initial peridotiteand that of the infiltrated melt may be distinguished in thereaction column: (1) a lower domain characterized by convex-upwardREE patterns similar to those observed in Ronda group C pyroxenite–peridotite;(2) an upper domain characterized by melts with strongly LREE-enrichedcompositions. The latter are probably volatile-rich, small-volumemelt fractions residual after the refertilization reactionsthat generated group C pyroxenites, which migrated throughoutthe massif—including the unmelted lithospheric spinel-tectonitedomain. The Ronda mantle domains affected by pyroxenite- anddunite- or harzburgite-forming reactions (the ‘layeredgranular’ subdomain and ‘plagioclase-tectonite’domain) are on average more fertile than the residual, ‘coarsegranular’ subdomain at the recrystallization front. Thisindicates that refertilization traces the moving boundariesof receding cooling of a thinned and partially melted subcontinentallithosphere. This refertilization process may be widespreadduring transient thinning and melting of depleted subcontinentallithospheric mantle above upwelling asthenospheric mantle. KEY WORDS: subcontinental mantle; refertilization; pyroxenite; peridotite; websterite; melt–rock reaction; plagioclase; trace elements  相似文献   

Progressive deformation of a zone of magma transfer in a transpressional regime: The Variscan Mérens shear zone (Pyrenees, France)   总被引：1，自引：0，他引：1  

Yoann Denle  Philippe Olivier  Grard Gleizes 《Journal of Structural Geology》2008,30(9):1138-1149

The EW-striking Variscan Mérens shear zone (MSZ), located on the southern border of the Aston dome (Pyrenees), corresponds to variously mylonitized gneisses and plutonic rocks that are studied using the Anisotropy of Magnetic Susceptibility (AMS) technique. The plutonic rocks form EW-striking bands with, from south to north, gabbro-diorites, quartz diorites and granodiorites. The MSZ underwent a mylonitic deformation with an intensity progressively increasing from the mafic to the more differentiated rocks. The foliations are EW to NW–SE striking and subvertical. A first set of lineations shows a moderate WNW plunge, with a dextral reverse kinematics. More recent subvertical lineations correspond to an uplift of the northern compartment. To the east, the MSZ was cut by a N120°E-striking late shear band, separating the MSZ from the Quérigut pluton. The different stages of mylonitization relate to Late Variscan dextral transpression. This regime allowed the ascent of magmas along tension gashes in the middle crust. We interpret the MSZ as a zone of magma transfer, which fed a pluton now eroded that was similar to the Quérigut and Millas plutons located to the east. We propose a model of emplacement of these plutons by successive pulses of magmas along en-échelon transfer zones similar to the MSZ.  相似文献