Modélisation de propagation d’écoulement entre lits mineur et majeur sur les fleuves Sénégal et Niger     

Jean-Claude Bader  Gilles Belaud  Jean-Pierre Lamagat  Thibaud Ferret  Philippe Vauchel 《水文科学杂志》2017,62(3):447-466

In the Senegal River valley and Niger Inner Delta, the annual floods inundate a wide floodplain consisting of a complex network of lakes and channels, where topographic information needed by standard hydraulic models is difficult to obtain. To represent the flood propagation between mainstream and floodplain, we use a model designed for flood propagation in river mainstreams with flat bed and large overflow and without topographic data. Depending on the water level in the riverbed, the model calibrated on the levels observed at two stations gives the level in the floodplains and propagation time between stations. Several cases are tested for various types of hydraulic connections between mainstream and floodplain. The model could correctly reproduce the flood rise and fall in the floodplain, even for a lake connected by a single channel to the riverbed or in the case of a strong attenuation of the flood between very distant stations.  相似文献   

War landform mapping and classification on the Verdun battlefield (France) using airborne LiDAR and multivariate analysis     

Rémi de Matos-Machado  Jean-Pierre Toumazet  Jean-Claude Bergès  Jean-Paul Amat  Gilles Arnaud-Fassetta  François Bétard  Clélia Bilodeau  Joseph P. Hupy  Stéphanie Jacquemot 《地球表面变化过程与地形》2019,44(7):1430-1448

Acting as efficient earth-movers, soldiers can be viewed as significant geomorphological drivers of landscape change when replaced in the recent debates on Anthropocene Geomorphology. ‘Polemoforms’, generated by military activities, correspond with a set of human-made landforms of various sizes and geometries. They are particularly common on the World War One battlefield of Verdun (France) which ranks among the largest battles of attrition along the Western Front. The artillery bombardments and building of defensive positions in that battle significantly altered the landscape, resulting in thousands of shell craters, dugouts, and gun positions that have altered both the meso and microtopography. This paper proposes an innovative methodology to make an exhaustive inventory of these small-scale conflict-induced landforms (excluding linear features such as trenches) using a digital terrain model (DTM) acquired by airborne LiDAR on the whole battlefield. Morphometric analysis was conducted using Kohonen's self-organizing maps (SOMs) and hierarchical agglomerative clustering (HAC) in order to quantify and classify the high number of war landforms. This combined approach allowed for mapping more than one million landforms which can be classified into eight different shapes including shell craters and various soldier-made landforms (i.e. shelters, gun positions, etc.). Detection quality evaluation using field observations revealed the algorithm successfully classified 93% of shell craters and 74% of anthropologically constructed landforms. Finally, the iconographic database and map series produced will help archaeologists and foresters to better manage the historic site of Verdun, today covered by a large forest of ~10 000 ha. © 2019 John Wiley & Sons, Ltd.  相似文献   

Benthic indicators and index approaches in the three main estuaries along the French Atlantic coast (Seine, Loire and Gironde)     

Jean-Claude Dauvin  Guy Bachelet  Anne-Laure Barillé  Hugues Blanchet  Xavier de Montaudouin  Nicolas Lavesque  & Thierry Ruellet 《Marine Ecology》2009,30(2):228-240

The three main estuaries in the French Atlantic coast – the Seine, Loire and Gironde, all with high tidal regimes – are interfaces between the continental and the coastal ecosystems. The Seine and Gironde are highly contaminated, whereas the Loire remains in a more natural state. Both the Seine and Gironde have suffered from harbour construction, and as a result, their biological units are extremely compartmentalized. Benthic species and communities have adapted to tolerate temporal physical and chemical changes ( e.g. salinity, substrata, depth, and levels of fine particles and oxygen) and human activities ( e.g. dredging, shipping traffic, and habitat reduction). Although numerous bio-indicators and indices are used to define the ecological quality status (EcoQS) of coastal waters, very few of them were developed specifically for environments with a mosaic of conditions and salinity levels, including freshwater. The main problem appears to be that all the indices for determining anthropogenic stress examine the abundances of stress-tolerant species, which may also be able to tolerate natural stressors such as those occurring in estuaries. This paper takes a look at the development status of the benthic indicators and index approaches used in the three main estuaries along the French Atlantic coast. In addition, it examines the adaptation of the different benthic indicators to the taxonomic sufficiency principle, and the adaptation of the Benthic Opportunistic Polychaetes Amphipods index (BOPA) and the Benthic Opportunistic Annelida Amphipod index (BO2A) for use in the freshwater zones of transitional waters ( i.e. up to the upper limit of the tidal range). Several perspectives are discussed in light of the diverse disturbances and the heterogeneity of such stressed zones, such as the use of multimetric and scoring approaches.  相似文献   

Ground temperature changes in eastern Canada: borehole temperature evidence compared with proxy data     

Hugo Beltrami  Jean-Claude Mareschal 《地学学报》1993,5(1):21-28

Borehole temperature logs have been inverted to infer ground temperature histories (GTH) in eastern and central Canada. Regional ground temperature histories were obtained by simultaneous inversion of several temperature profiles from the same areas. Simultaneous inversion of 21 temperature logs sampled across all of eastern and central Canada yielded an average solution for this region. All but three of the studied sites show signs of warming in the last 150 years. This period of warming, which started after 1800 AD, was found throughout this part of Canada. The warming followed a cooler period corresponding to the little Ice Age. The inferred ground temperature histories exhibit long-term trends similar to those obtained from treering growth indices in nearby regions and stable isotope data in the southern hemisphere. The modern warming appears correlated with the atmospheric concentration of CO₂ as measured in ice cores.  相似文献   

Bücher- und Zeitschriftenschau     

Steinmann  Schöndorf  W. Salomon 《International Journal of Earth Sciences》1915,6(1-2):94-102

Ohne Zusammenfassung  相似文献   

Impact of amoco cadiz oil spill on the muddy fine sand Abra alba and Melinna palmata community from the Bay of Morlaix     

Jean-Claude Dauvin 《Estuarine, Coastal and Shelf Science》1982,14(5):517-531

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Magma evolution of Quaternary minor volcanic centres in southern Peru,Central Andes   总被引：1，自引：0，他引：1  

Adélie Delacour  Marie-Christine Gerbe  Jean-Claude Thouret  Gerhard Wörner  Perrine Paquereau-Lebti 《Bulletin of Volcanology》2007,69(6):581-608

Minor centres in the Central Volcanic Zone (CVZ) of the Andes occur in different places and are essential indicators of magmatic processes leading to formation of composite volcano. The Andahua–Orcopampa and Huambo monogenetic fields are located in a unique tectonic setting, in and along the margins of a deep valley. This valley, oblique to the NW–SE-trend of the CVZ, is located between two composite volcanoes (Nevado Coropuna to the east and Nevado Sabancaya to the west). Structural analysis of these volcanic fields, based on SPOT satellite images, indicates four main groups of faults. These faults may have controlled magma ascent and the distribution of most centres in this deep valley shaped by en-echelon faulting. Morphometric criteria and ¹⁴C age dating attest to four main periods of activity: Late Pleistocene, Early to Middle Holocene, Late Holocene and Historic. The two most interesting features of the cones are the wide compositional range of their lavas (52.1 to 68.1 wt.% SiO₂) and the unusual occurrence of mafic lavas (olivine-rich basaltic andesites and basaltic andesites). Occurrence of such minor volcanic centres and mafic magmas in the CVZ may provide clues about the magma source in southern Peru. Such information is otherwise difficult to obtain because lavas produced by composite volcanoes are affected by shallow processes that strongly mask source signatures. Major, trace, and rare earth elements, as well as Sr-, Nd-, Pb- and O-isotope data obtained on high-K calc-alkaline lavas of the Andahua–Orcopampa and Huambo volcanic province characterise their source and their evolution. These lavas display a range comparable to those of the CVZ composite volcanoes for radiogenic and stable isotopes (⁸⁷Sr/⁸⁶Sr: 0.70591–0.70694, ¹⁴³Nd/¹⁴⁴Nd: 0.512317–0.512509, ²⁰⁶Pb/²⁰⁴Pb: 18.30–18.63, ²⁰⁷Pb/²⁰⁴Pb: 15.57–15.60, ²⁰⁸Pb/²⁰⁴Pb: 38.49–38.64, and δ ¹⁸O: 7.1–10.0‰ SMOW), attesting to involvement of a crustal component. Sediment is absent from the Peru–Chile trench, and hence cannot be the source of such enrichment. Partial melts of the lowermost part of the thick Andean continental crust with a granulitic garnet-bearing residue added to mantle-derived arc magmas in a high-pressure MASH [melting, assimilation, storage and homogenisation] zone may play a major role in magma genesis. This may also explain the chemical characteristics of the Andahua–Orcopampa and Huambo magmas. Fractional crystallisation processes are the main governors of magma evolution for the Andahua–Orcopampa and Huambo volcanic province. An open-system evolution is, however, required to explain some O-isotopes and some major and trace elements values. Modelling of AFC processes suggests the Charcani gneisses and the local Andahua–Orcopampa and Huambo basement may be plausible contaminants.  相似文献   

Expertise in coastal zone environmental impact assessments     

Dauvin JC 《Marine pollution bulletin》2005,50(1):107-110

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Relief and Gravity Anomalies Over a Convecting Mantle     

Jean-Claude De Bremaecker 《Geophysical Journal International》1976,45(2):349-356

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Analysis of a UV Event in a Polar Coronal Hole     

Patsourakos  Spiros  Vial  Jean-Claude 《Solar physics》2001,203(1):39-51

We present observations of a UV event which occurred in a polar coronal hole. They were obtained by SUMER on SOHO in several chromospheric and transition region spectral lines. Its birth site was about 50 arc sec inside the limb and in a network lane showing a net outflow before its initiation. The event had an extension of about 5 arc sec along the slit, a duration of about 3 min and was characterized by a large increase of intensity together with a significant line broadening with, however, downflows of about 50 km s^–1 being dominant. Proper motions with a velocity of about 10 km s^–1 were also observed. The event appeared at middle transition (Ovi) temperatures and it simultaneously showed up in chromospheric (Oi, Ly ) and low transition region (Cii) temperatures. We discuss this event in view of different scenarios to account for it. Our event could be a part of the large family of quiet-Sun explosive events observed by Ryutova and Tarbell (2000) taking place in polar coronal holes that are triggered by magnetic reconnection in the low solar atmosphere.  相似文献