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Complex para-glacial systems may show signs of destabilization leading to frequent and potentially hazardous debris-flows. Understanding creeping permafrost displacement over a period of time is therefore crucial for hazard management and risks assessment. This paper presents our methodology for estimating creeping permafrost displacement based upon data derived from various survey methods and demonstrates its relevance on the Glacier Bonnard system in southern Switzerland. Geostatistical processing allowed estimation of the displacement intensity over the area of interest, as well as assessment of the interpolation quality. Although the local measurement network needs to be refined, the results largely improve the understanding of the Bonnard para-glacial system, though highlighting the need to locally refine the measurement network. In the present case, the destabilized front advances at ~1 m/a and the upstream creeping part at ~0.4 m/a. Variance analysis also provide objective thresholds that could be used to distinguish underlying physical processes. Copyright © 2015 John Wiley & Sons, Ltd.

The Glacier Bonnard is a rock glacier located in the State of Valais, Switzerland. It overhangs a settlement and its slow downward constant creep constitutes an environmental hazard. It is therefore important to understand the glacier’s internal structure, particularly in terms of ice content, in order to evaluate its current global dynamic and future evolution. Following preliminary geophysical investigations, several boreholes have been drilled to measure the thickness of the glaciated mass and the vertical distribution of lithology and ice content. These new data are helpful in assessing the amount of ice within the Glacier Bonnard. Two geostatistical modeling approaches are considered: a direct modeling of ice content and an indirect approach linking together lithology and ice content by the use of the plurigaussian algorithm. Comparisons between these approaches are made in terms of ice content prediction and of global ice mass within the sampled area; they underline the benefit of the geostatistical modeling and particularly the advantages of the indirect approach.

A collection of local and regional point daily and monthly rainfall data series is used to illustrate the anisotropy affecting meteorological rainfall totals in North-Eastern France. Their relationship with geographical or atmospherical factors likely to explain their spatial patterns at different spatial scales is also presented. A method of spatial interpolation incorporating an auxiliary geographical information at meso-scale is then applied to a strong windy rainfall event. An attempt to account for the micro-scale variability into the procedure of meteorological rainfall estimation is finally performed., À la faveur d’un effort important de collecte et de validation de données pluviométriques quotidiennes et mensuelles à l’échelle régionale et locale dans le Nord-Est français, on rappelle comment s’exprime l’hétérogénéité spatiale du flux de précipitations et quels sont les facteurs géographiques ou atmosphériques susceptibles de l’expliquer aux différents niveaux scalaires. Une méthode d’interpolation spatiale permettant de prendre en compte une information géographique exogène dans la spatialisation à méso-échelle du flux de précipitations est ensuite appliquée à un épisode pluvieux et venteux. Une tentative de prise en compte de la micro-variabilité spatiale dans la cartographie du flux de précipitations est également présentée dans le but de produire une représentation multiscalaire du phénomène géographique étudié., Jeannée Nicolas, Adzijian-Gérard Jocelyne, Drogue Gilles, Francois Didier. La répartition spatiale des précipitations à différentes échelles dans le Nord-Est français : observations et cartographie (The spatial distribution of rainfall at different scales in Northeastern France : observations and mapping). In: Bulletin de l'Association de géographes français, 87e année, 2010-2. Approches spatiales multiscalaires en climatologie. pp. 245-260.

The objective of this work is to combine several approaches to better understand nitrate fate in the Grand Morin aquifers (2700 km2), part of the Seine basin. cawaqs results from the coupling of the hydrogeological model newsam with the hydrodynamic and biogeochemical model of river ProSe . cawaqs is coupled with the agronomic model Stics in order to simulate nitrate migration in basins. First, kriging provides a satisfactory representation of aquifer nitrate contamination from local observations, to set initial conditions for the physically based model. Then associated confidence intervals, derived from data using geostatistics, are used to validate cawaqs results. Results and evaluation obtained from the combination of these approaches are given (period 1977–1988). Then cawaqs is used to simulate nitrate fate for a 20-year period (1977–1996). The mean nitrate concentrations increase in aquifers is 0.09 mgN L−1 yr−1, resulting from an average infiltration flux of 3500 kgN.km−2 yr−1.

Resume Dans les sols heterogenes, l'importante variabilite spatiale des teneurs rend les estimations peu precises. Celles-ci peuvent-elles etre ameliorees grâce a des informations qualitatives, peu precises, mais potentiellement abondantes ? Plusieurs criteres de comparaison d'indices qualitatifs sont proposes, dont sont deduites differentes variables auxiliaires pour un cokrigeage avec les teneurs. Pour un ancien site de cokerie, nous montrons l'amelioration sur l'estimation des teneurs en benzo(a)pyrene que permet l'utilisation des releves organoleptiques dans les sols. Pour citer cet article : N. Jeannee, C. de Fouquet, C. R. Geoscience 335 (2003). Pour citer cet article : N. Jeannee, C. de Fouquet, C. R. Geoscience 335 (2003).

International audience; Although spatial studies of diseases on land have a long history, far fewer have been made on aquatic diseases. Here, we present the first large-scale, high-resolution spatial and temporal representation of a mass mortality phenomenon cause by the Ostreid herpesvirus (OsHV-1) that has affected oysters (Crassostrea gigas) every year since 2008, in relation to their energetic reserves and the quality of their food. Disease mortality was investigated in healthy oysters deployed at 106 locations in the Thau Mediterranean lagoon before the start of the epizootic in spring 2011. We found that disease mortality of oysters showed strong spatial dependence clearly reflecting the epizootic process of local transmission. Disease initiated inside oyster farms spread rapidly beyond these areas. Local differences in energetic condition of oysters, partly driven by variation in food quality, played a significant role in the spatial and temporal dynamics of disease mortality. In particular, the relative contribution of diatoms to the diet of oysters was positively correlated with their energetic reserves, which in turn decreased the risk of disease mortality.

International audience; Geostatistics applied to radiological evaluation of nuclear premises provides methods to estimate radiological activities, together with their associated uncertainty. These tools enable to set up a sophisticated sampling methodology combining radiation map and destructive samples. The radiological assessment is divided into two steps: first, a systematic (exhaustive) control of the surface activity is performed. Then, to assess the true contamination, concrete samples are collected and analyses are performed at several locations within the premises. These two types of measurement are first dealt separately, then cokriging is applied to estimate the contamination over the premise, taking both measurements into account. This work provides a methodological study of geostatistical and computational approaches to target suitable areas for additional radiological measures. In order to compare the proposed augmented sampling designs, several optimization criteria can be taken into account. Their diversity ensures the coverage of a wide range of practical problematics. Two algorithms (greedy algorithm and simulated annealing) are developed to optimize the chosen criterion value as a function of the location of the additional points. The sampling scenarios obtained with the different algorithms are compared in terms of optimization performance and computational efficiency.

L’evaluation des impacts sanitaires lies a la pollution atmospherique requiert la connaissance quantifiee de l’exposition des populations. Cette exposition peut etre mesuree ou estimee, individuellement ou collectivement. Au plan collectif, plusieurs approches permettent d’estimer la repartition spatiale des expositions : 1) l’approche dite « deterministe » part de l’inventaire des sources et de leurs flux d’emission et calcule les concentrations atmospheriques resultantes, 2) l’approche dite « probabiliste » spatialise des resultats de mesures issues du reseau de surveillance de la qualite de l’air par interpolation geostatistique. Outre leurs incertitudes propres, la pertinence de ces deux approches depend des objectifs de l’etude des impacts sanitaires. Concernant la prevision des benefices sanitaires attribuables aux normes limitant les emissions des vehicules routiers, une combinaison des deux approches s’avere necessaire. Cette combinaison est possible par l’intermediaire des methodes geostatistiques, qui presentent en outre l’avantage de fournir une estimation des incertitudes liees a la cartographie du polluant. L’objectif de cette etude est donc de tester la faisabilite d’une approche combinee deterministe/ probabiliste pour la determination de la repartition spatiale de l’exposition moyenne annuelle aux PM10 en France metropolitaine en 2000. Elle fait partie d’une etude portant sur l’evaluation des impacts sanitaires de la pollution atmospherique liee au trafic routier dans les zones urbaines, en se focalisant en particulier sur les enfants et en comparant les situations en 2000 et en 2010. Cette etude s’inscrit dans le cadre du programme UNECE-WHO Pan European Program for Transport, Health and Environment (THE PEP Project): « Transport-related health impacts and their costs and benefits with a particular focus on children ».Les avantages et inconvenients des methodes permettant d’evaluer l’exposition des populations a la pollution atmospherique sont tout d’abord discutes. Le cas d’etude et les principales etapes d’une combinaison geostatistique sont ensuite presentes, ainsi que les resultats obtenus pour l’evaluation des populations exposees aux PM10 en France en 2000.

International audience