The Weierbach experimental catchment in Luxembourg: A decade of critical zone monitoring in a temperate forest - from hydrological investigations to ecohydrological perspectives     

Christophe Hissler  Núria Martínez-Carreras  François Barnich  Laurent Gourdol  Jean François Iffly  Jérôme Juilleret  Julian Klaus  Laurent Pfister 《水文研究》2021,35(5):e14140

The Weierbach experimental catchment (0.45 km²) is the most instrumented and studied sub-catchment in the Alzette River basin in Luxembourg. Within the last decade, it has matured towards an interdisciplinary critical zone observatory focusing on a better understanding of hydrological and hydro-geochemical processes. The Weierbach catchment is embedded in an elevated sub-horizontal plateau, characterized by slate bedrock and representative of the Ardennes Massif. Its climate is semi-marine, with precipitation being rather evenly distributed throughout the year. Base flow is lowest from July to September, essentially due to higher losses through evapotranspiration in summer. The regolith is composed of Devonian slates, overlaid by Pleistocene slope deposits and entirely covered by forest with 70% deciduous and 30% coniferous trees. Since 2009, the Weierbach has been extensively equipped for continuously monitoring water fluxes and physico-chemical parameters within different compartments of the critical zone. Additionally, these compartments are sampled fortnightly at several locations to analyze δ¹⁸O and δ²H isotopic composition of water including rainfall, throughfall, soil water, groundwater and streamwater. This ongoing monitoring and sampling programme is used for answering pressing questions related to fundamental catchment functions of water infiltration, storage, mixing and release in forest ecosystems. A recently started research line aims at investigating interactions between forest eco-hydrosystems with the atmosphere and understanding how catchments will respond to a non-stationary climate.  相似文献   

Découverte d’un chevauchement d’âge quaternaire au sud de la Grande Kabylie (Algérie)     

Azzedine Boudiaf  Hervé Philip  Alain Coutelle  Jean-François Ritz 《Geodinamica Acta》2013,26(2):71-80

Résumé

À l’échelle du Maghreb, la Kabylie (Algérie) est considérée comme une région asismique. L’étude détaillée des données de la sismicité historique et instrumentale de cette région montre une activité sismique modérée depuis au moins un siècle et demi (M₁ = 5,0). Les observations géomorphologiques faites sur le versant sud du massif kabyle, s’appuyant sur l’analyse d’images satellites, de photos aériennes et de la topographie, nous ont permis de démontrer la présence d’une activité tectonique quaternaire le long de la rupture de pente au sud de ces massifs. Elle correspond à la réactivation de chevauchements d’âge miocène qui se manifestent par des escarpements d’au moins 10 m affectant le glacis d’âge quaternaire ainsi que les cônes de déjection. Ces escarpements sont interprétés comme des ruptures probablement associées à une succession de séismes de forte magnitude. Les observations que nous décrivons se situent dans la région de Tazmalt et de Boüira où ces déformations sont les plus spectaculaires. L’ampleur des déformations quaternaires qui affectent l’ensemble de cette région considérée jusqu’à l’heure actuelle comme asismique ou faiblement sismique pose, comme dans la plupart des régions intracontinentales, le problème de la période de retour des séismes de forte magnitude. © Elsevier, Paris  相似文献   

Paleomagnetic results from the Permian Rodez basin implications: the Late Variscan tectonics in the southern French Massif Central     

Arturo Diego-Orozco  Yan Chen  Bernard Henry  Jean-François Becq-Giraudon 《Geodinamica Acta》2013,26(4):249-260

Abstract

A paleomagnetic study has been carried out on three sedimentary formations of the Permian Rodez basin in the southern France. Two of them yield paleomagnetic poles of Saxonian and Thuringian age showing counterclockwise rotation of moderate amplitude, during or after the Thuringian deposition. For the French Massif Central, contrary to its stable southern (Lodève basin) and eastern (Largentière basin) borders, on its southwestern border, in a large area including the Rodez, Saint-Affrique and perhaps Brive basins suffered rotations due to the extensional tectonics during the Late Variscan period. © 2002 Editions scientifiques et médicales Elsevier SAS. All rights reserved.  相似文献   

Evaluating drivers of land-use change and transition potential models in a complex landscape in Southern Mexico     

Melanie Kolb  Jean-François Mas  Leopoldo Galicia 《International journal of geographical information science》2013,27(9):1804-1827

Understanding and analysis of drivers of land-use and -cover change (LUCC) is a requisite to reduce and manage impacts and consequences of LUCC. The aim of the present study is to analyze drivers of LUCC in Southern Mexico and to see how these are used by different conceptual and methodological approaches for generating transition potential maps and how this influences the effectiveness to produce reliable LUCC models. Spatial factors were tested for their relation to main LUCC processes, and their importance as drivers for the periods 1993–2002 and 2002–2007 was evaluated by hierarchical partitioning analysis and logistic regression models. Tested variables included environmental and biophysical variables, location measures of infrastructure and of existing land use, fragmentation, and demographic and social variables. The most important factors show a marked persistence over time: deforestation is mainly driven by the distance of existing land uses; degradation and regeneration by the distance of existing disturbed forests. Nevertheless, the overall number of important factors decreases slightly for the second period. These drivers were used to produce transition potential maps calibrated with the 1993–2002 data by two different approaches: (1) weights of evidence (WoE) to represent the probabilities of dominant change processes, namely deforestation, forest degradation, and forest regeneration for temperate and tropical forests and (2) logistic RM that show the suitability regarding the different land-use and -cover (LUC) classes. Validation of the transition potential maps with the 2002–2007 data indicates a low precision with large differences between LUCC processes and methods. Areas of change evaluated by difference in potential showed that WoE produce transition potential maps that are more accurate for predicting LUCC than those produced with RM. Relative operating characteristic (ROC) statistics show that transition potential models based on RM do usually better predict areas of no change, but the difference is rather small. The poor performance of maps based on RM could be attributed to their too general representation of suitability for certain LUC classes when the goal is modeling complex LUCC and the LUC classes participate in several transitions. The application of a multimodel approach enables to better understand the relations of drivers to LUCC and the evaluation of model calibration based on spatial explanatory factors. This improved understanding of the capacity of LUCC models to produce accurate predictions is important for making better informed policy assessments and management recommendations to reduce deforestation.  相似文献   

Mapping urban fingerprints of odonyms automatically extracted from French novels     

Ludovic Moncla  Mauro Gaio  Thierry Joliveau  Yves-François Le Lay  Noémie Boeglin  Pierre-Olivier Mazagol 《International journal of geographical information science》2013,27(12):2477-2497

ABSTRACT

In this paper, we propose and discuss a methodology to map the spatial fingerprints of novels and authors based on all of the named urban roads (i.e., odonyms) extracted from novels. We present several ways to explore Parisian space and fictional landscapes by interactively and simultaneously browsing geographical space and literary text. Our project involves building a platform capable of retrieving, mapping and analyzing the occurrences of named urban roads in novels in which the action occurs wholly or partly in Paris. This platform will be used in several areas, such as cultural tourism, urban research, and literary analysis. The paper focuses on extracting named urban roads and mapping the results for a sample of 31 novels published between 1800 and 1914. Two approaches to the annotation of odonyms are compared. First, we describe a proof of concept using queries made via the TXM textual analysis platform. Then, we describe an automatic process using a natural language processing (NLP) method. Additionally, we mention how the geosemantic information annotated from the text (e.g., a structure combining verbs, spatial relations, named entities, adjectives and adverbs) can be used to automatically characterize the semantic content associated with named urban roads.  相似文献   

Land change modelling: moving beyond projections     

Martin Paegelow  María Teresa Camacho Olmedo  Jean-François Mas  Thomas Houet  Robert Gilmore Pontius Jr. 《International journal of geographical information science》2013,27(9):1691-1695

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Planets and Planet-Sized Binaries from the OGLE Transit Survey     

Frédéric Pont  François Bouchy 《Astrophysics and Space Science》2006,304(1-4):235-238

The OGLE survey for transiting planets has identified 177 transit candidates. Subsequent radial velocity follow-up of these candidates has allowed the detection of five transiting planets, as well as several dozen eclipsing binaries.Some of these systems consist of solar-type stars transited by small M dwarf companion, including the smallest stellar companions yet measured by transit. As a result, the OGLE transit survey has yielded a wealth of data on the mass-radius relation of planets and low-mass stars. In particular, two planet-sized stars were found, an empirical proof of the model predictions on Jupiter-sized main-sequence stars.  相似文献   

Uranium and thorium isotopes in the rivers of the Amazonian basin: hydrology and weathering processes     

Aguinaldo N. Marques  Iyad Al‐Gharib  Michel Bernat  Franois Fernex 《水文研究》2003,17(1):17-31

Two expeditions (October 1989 and May 1992) were carried out to two points of the main Amazon River channel and four tributaries. The Solimões and Madeira rivers, taking their origin in the Andes, are whitewater rivers. The Negro River is a typical acid, blackwater river. The Trombetas River flows through bauxite‐rich areas, and is characterized by low concentrations of dissolved humic substances. The ²³⁸U, ²³⁴U, ²³²Th and ²³⁰Th activities were recorded from dissolved, suspended particulate phases and river bank sediments. The latter were analysed for their ²²⁶Ra, ²²⁸Ra and ²¹⁰Pb contents, and also subjected to leaching with 0·2 M hydroxylamine–hydrochloride solution to determine the concentrations of radionuclides bound to amorphous Fe hydroxides and Mn oxides and hydroxides. The dissolved U average concentration in the Amazon system is ten times lower than the mean world river concentration. The uranium concentration observed at Óbidos in the lower Amazon (0·095 µg L^?1), where the U content in the river bank sediments and suspended matter is lowest, suggests U release from the solid phase during river transport. About 485 t of U are transported annually to the Amazon delta area in dissolved form, and 1943 t bound to suspended particulate matter. Total U and Th concentrations in the river bank sediments ranged from 1·59 to 7·14 µg g^?1 and from 6·74 to 32 µg g^?1, respectively. The highest concentrations were observed in the Trombetas River. The proportion extracted by means of the hydroxylamine solution (HL) was relatively high for U in the Trombetas river bank sediment (31%) and for Th in the Solimões sediment (30%). According to the alpha recoil effects, the ²³⁴U/²³⁸U activity ratios of the Andean river waters and downstream Amazon water (Óbidos) were >1, but were <1 in the Negro River (at Manaus). The activity ratios of dissolved U correlate with pH and also with the U activity ratios in the river bank sediment hydroxylamine extracts. As expected, the ²³⁴U/²³⁸U activity ratios in river bank sediments were <1 in the Andean rivers and in the downstream Amazon, but they were >1 in the Trombetas and Negro rivers. Such ratios probably result from the binding of dissolved uranium to solid sediment. The ²²⁸Th/²³²Th ratios of river bank sediments were close to unity (except for the Negro River, where it is lower), suggesting no significant Th exchanges between the river water and the sediment. The ²²⁶Ra/²³²Th activity ratios were <1, and the ²²⁶Ra/²²⁸Ra activity ratios generally were significantly higher than the activity ratios of their respective parents. This perhaps is the result of easier leaching of the ²²⁶Ra parent, ²³⁰Th, from solid material (owing to the alpha recoil effect) than of the ²²⁸Ra parent. Uranium and thorium isotopes were used as tools to evaluate the chemical weathering rate of rocks in the Amazon system, which was estimated to be 2·7 cm 1000 year^?1 s^?1. Copyright © 2002 John Wiley & Sons, Ltd.  相似文献   

Dating faulted alluvial fans with cosmogenic ¹⁰Be in the Gurvan Bogd mountain range (Gobi-Altay, Mongolia): climatic and tectonic implications     

Riccardo Vassallo  Jean-François Ritz  Régis Braucher  Sébastien Carretier 《地学学报》2005,17(3):278-285

The Gurvan Bogd mountain range is a fault system characterized by strong earthquakes (M ∼ 8) separated by long periods of quiescence. Further to the previous works in the area, our study provides new data concerning the tectonic and climatic processes in the Gobi-Altay. To quantify the slip rates along the faults, we dated offset alluvial fans analysing the in situ produced ¹⁰Be along profiles at depth. The slip rates along the Bogd strike–slip fault and its associated thrust faults over the Upper Pleistocene–Holocene period are 0.95 ± 0.29 mm yr⁻¹ and comprised between 0.12 ± 0.02 and 0.13 ± 0.02 mm yr⁻¹, respectively. The surfaces ages account for a cyclic formation of the fans over the past ∼360 ka, in correlation with the terminations of the marine isotope stages 2, 6, 8 and 10.  相似文献   

Improvement of TOPLATS‐based discharge predictions through assimilation of ERS‐based remotely sensed soil moisture values     

Valentijn R. N. Pauwels  Rudi Hoeben  Niko E. C. Verhoest  Franois P. De Troch  Peter A. Troch 《水文研究》2002,16(5):995-1013

In this paper, we investigate the possibility to improve discharge predictions from a lumped hydrological model through assimilation of remotely sensed soil moisture values. Therefore, an algorithm to estimate surface soil moisture values through active microwave remote sensing is developed, bypassing the need to collect in situ ground parameters. The algorithm to estimate soil moisture by use of radar data combines a physically based and an empirical back‐scatter model. This method estimates effective soil roughness parameters, and good estimates of surface soil moisture are provided for bare soils. These remotely sensed soil moisture values over bare soils are then assimilated into a hydrological model using the statistical correction method. The results suggest that it is possible to determine soil moisture values over bare soils from remote sensing observations without the need to collect ground truth data, and that there is potential to improve model‐based discharge predictions through assimilation of these remotely sensed soil moisture values. Copyright © 2002 John Wiley & Sons, Ltd.  相似文献