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Guide des Curiosités Géologiques de la Creuse
No full textNational audienceLe granite est roi en ces terres, concourant à la réputation de ses habitants bâtisseurs, attachés à leurs racines, à leurhistoire et à leurs paysages faits de rondeurs verdoyantes, boisés de forêts mystérieuses et parfois interrompues deprofondes vallées ayant inspiré les plus grands peintres.De la Marche au plateau de Millevaches en passant de la Combraille aux monts de Guéret, la Creuse expose une richegéodiversité : chaos, étangs et sources, ressources minérales, cascades, roches diverses et variées.Des paysages naturels issus de plusieurs millions d’années d’évolution reposant sur un sous-sol dont le patrimoinegéologique constitue le socle pour tous les autres. Indissociable de celle du Massif central, l’histoire géologique de la Creuserésulte d’une évolution complexe sur près de 550 millions d’années !24 sites remarquables vous feront découvrir la géodiversité à l’origine des magnifi ques paysages de cette partie du Limousin.Et pour parfaire ce tour d’horizon géologique, un aperçu de la biodiversité creusoise vous est proposé
Visualizing uncertainty from meteo-oceanic ensemble data
No full textPaper has been accepted for presentation at the VIS 2025 Uncertainty Visualization workshop in Vienna, Austria and for inclusion in the IEEE proceedings.Accurate and timely forecasts represent a fundamental asset to mitigate damages due to natural disasters such as coastal flooding related to storm events. The production of such forecasts is based on the interpretation of data from various sources (local sensors, satellite imagery, simulated meteo-oceanic conditions) by experts of these meteorological phenomena. Visualization is a powerful tool for meteorological forecasters in order to cross these different information, make sense of large volumes of simulated meteo-oceanic data, while taking into account the uncertainty, inherent in natural phenomena or any dynamic complex system. The use of ensemble simulation (based on the generation of a set of possible future scenarios analyzed as a whole, instead of a single one) offers a way for forecasters to better integrate the uncertainty related to meteo-oceanic simulation models in the determination of vigilance levels, allowing to face the growing demand for ever more precise and higher-resolution local forecasts. However, the difficult task of visualizing spatio-temporal multivariate data for meteorological forecasters becomes even more complex when dealing with many ensemble scenarios, especially if forecasters have to get an overview of the phenomena through the entire set of scenarios. Furthermore, forecasters need bespoke visualizations that meet the demands of delivering vigilance warnings in daily operational settings. Uncertainty indicators can however be extracted by aggregating ensemble outputs, and be encoded through different cartographic approaches, allowing to visualize, for example, the spatial distribution of main trend among possible scenarios with a corresponding confidence interval. In this paper we present different geovisualization approaches, aiming to help the visual analysis of ensemble meteo-oceanic data in the context of coastal flooding forecast. These approaches use different ways to aggregate ensemble simulation outputs, and to encode the calculated indicators combining bivariate color scales and grid-distributed glyphs of different designs, which offers different points of view on the scenarios distribution. These different approaches were co-constructed with meteorological forecasters and other coastal flooding experts, and finally submitted to their manipulation. We present also the feedback of these experts users regarding these different propositions, which gives an insight about which type of representation could better answer their scientific or operational needs
Design for numerical simulation of induced seismicity using multi-scale heterogeneity model
No full textInternational audienceThe principal mechanism of any induced seismicity is an increase in pore pressure whereas the one of natural seismicity is a change in stress field and surrounding aseismic slip. Multi-scale heterogeneity model of a fault has been suitable for the fault behavior from a macroscopic point of view in which any small perturbation (a nucleation process) may grow up to any scale even if the shear stress did not reach the fault strength at the beginning and thus the nucleation point was stochastically chosen. However, this choice needs to be more reasonable for the context of the induced seismicity. In Aochi & Ide ( 2009), the nucleation is chosen according to a weighting function in stress accumulation, implicitly assuming the expected seismicity rate which is low enough compared to the loading rate. In this study, we introduce stochastically a fault strength only for determining the rupture initiation ("initiation fault strength") on the smallest patches of the model, described with a Weibull function, while we keep the uniform macroscopic fault strength over a fault. Every small patch is ruptured once the stress reaches the initiation fault strength. This includes no assumption on the seismicity rate and allows us to discuss the pore pressure change and the seismicity rate
Assessing accessibility to quiet and green areas at the city scale using an agent-based transport model
No full textInternational audienceStandard European approaches to assessing environmental noise focus on individuals exposed to critical noise levels. However, there are complementary approaches that question the accessibility of the population to quiet areas, highlighting the restorative properties of natural and quiet spaces for human health. In this regard, from an agent-based model, this study proposes a spatio-temporal methodology to assess accessibility to quiet areas in agglomerations, integrating everyday mobility into the analysis of place effects and opportunities. The two primary objectives are to identify current quiet areas that are accessible in order to preserve them acoustically and to identify green spaces with the greatest potential for accessibility in order to improve them acoustically. Green spaces of Lyon and Villeurbanne (France) are assessed during the lunch break period using an open-source framework. The results indicate that on average about 30% of agents have access to a quiet area. Further, green spaces in courtyards represent the current quiet areas with the greatest accessibility. Concerning spaces with great potential for accessibility, linear green spaces along rivers and small squares near high-attended urban centers represent the greatest potential gain in accessibility to quiet areas. Improvements pertain to the utilization of in-situ surveys to integrate human perception and place attendance evaluations in the formulation of action plans
Analyse et identification de Plans de Gestion de Données disciplinaires pouvant être utilisés comme exemple: Produit du Groupe de Travail PGD Disciplinaires de RDA France
No full textRDA France, le chapitre français de la Research Data Alliance (RDA), a mis en place en mars 2023 le groupe de travail RDA France – Plans de Gestion de Données disciplinaires (GT PGD-DISC), avec l’objectif de constituer un corpus de plans de gestion des données (PGD) disciplinaires pouvant être utilisés comme exemple. Ce document décrit en introduction les raisons pour lesquelles RDA France a créé ce groupe de travail et la manière dont le groupe a été constitué (Section 1), puis la méthodologie employée pour élaborer le corpus (Section 2) et le contenu de celui-ci, en termes de données et de métadonnées (Section 3). La maintenance envisagée pour le corpus est décrite en conclusion (Section 4).La Version 1 de la liste de plans de gestion de données disciplinaires résultant du travail du groupe est publiée dans l’entrepôt de l’infrastructure Recherche Data Gouv (https://doi.org/10.57745/ZSWLYJ)
Intégrité des écosystèmes : approches scientifiques et implications pratiques
No full textSource Agritrop Cirad (https://agritrop.cirad.fr/612484/)International audienceCette " Expertise et synthèse " présente d'abord l'intégrité des écosystèmes comme une approche applicable à tous les écosystèmes ; elle discute ensuite cette notion au regard des pressions anthropiques et des changements globaux puis évoque quelques perspectives d'utilisation et limites
Fate of an analogous molecule of hydroxypyridone alkaloids with potentially phytosanitary properties in the vadose zone of the Beauce aquifer (France)
No full textInternational audienceWith the aim of developing a new biodegradable pesticide, batch and transport experiments of a 4-hydroxy-2-pyridone core molecule (4H2P), were carried out through agricultural soil and limestone columns. 4H2P cores are natural biodegradable compounds with diverse biological activities, including fungicidal and bactericidal properties. The results of the transport experiments indicated that the 4H2P molecule is adsorbed in agricultural soil (with a retention rate of 35 %), but not on limestone (with a zero-retention rate). Modeling of the transport data also revealed a higher retardation coefficient in soil (R = 6.04) than in limestone (R = 1.00). Isotherms experiments modeling revealed that the constants "n" of the Freundlich model are < 1 and the free adsorption energy parameters "E" of the Dubinin Radushkevich model are about 4 kJ.mol−1 < < 8 kJ.mol−1 which indicates that the adsorption of the 4H2P molecule by the solid phases (Calcite, kaolinite and montmorillonite) is of physisorption type with montmorillonite exhibiting significant adsorption capacity (with Qm = 12.10−3 mol.g−1). X-ray diffraction analysis of montmorillonite before and after adsorption showed that the molecule is inserted between the intermediate layers from a concentration of 0.5 gL−1, with a disorganization in the stacking of the layers involved from 1.5 g.L−1
Bidirectional Translations Between Observational and Topography‐Based Hydrographic Data Sets: MERIT‐Basins and the SWOT River Database (SWORD)
No full textInternational audienceThe recently launched Surface Water and Ocean Topography (SWOT) Mission is expected to provide transformative observations of water surface elevation, width, and slope and produce derived estimates of discharge for global rivers along rivers in the SWOT River Database (SWORD). However, the hydrographic representation of rivers in SWORD differs from hydrography data sets commonly used for modeling purposes, such as Multi-Error-Removed Improved Terrain (MERIT)-Basins. Here, we develop links between the river networks of SWORD and MERIT-Basins (MB) to enable interoperability between SWOT data products and hydrologic modeling frameworks. This data set, termed MERIT-SWORD, identifies a subset of ∼277,000 global MB river reaches that most closely represent the location and extent of the SWORD river network and establishes bidirectional, one-to-many translations between reaches in the two hydrographic data sets. The MERIT-SWORD data set serves to unite SWOT observations with river routing models, allowing for the seamless and standardized assimilation of SWOT vector products into global river simulations and the provision of improved a priori discharge estimates for SWOT discharge computation. Plain Language SummaryThe Surface Water and Ocean Topography (SWOT) Mission observes the water surface elevation, width, and slope of river reaches described in the SWOT River Database (SWORD). The location and extent of rivers in SWORD differ considerably from other river network data sets that are commonly used for hydrological modeling such as Multi-Error-Removed Improved Terrain (MERIT)-Basins. Here, we present and publicly share the MERIT-SWORD data set which links rivers in SWORD to rivers in MERIT-Basins (MB), and vice versa. These links between river reaches in the two data sets can allow for model simulations to be used as a first guess for SWOT measurements, and for observations from SWOT to be easily transferred to hydrologic modeling frameworks based on the MB river network for data assimilation
Groundwater Level Projections for Aquifers Affected by Annual to Decadal Hydroclimate Variations: Example of Northern France
No full text(IF2.8;Q1)International audienceIn a context where anticipating future trends and long-term variations in water resources is crucial, improving our knowledge about most types of aquifer responses to climate variability and change is necessary. Aquifers with variability dominated by seasonal (marked annual cycle) or low-frequency variations (interannual to decadal variations driven by large-scale climate dynamics) may encounter different sensitivities to climate change. We investigated this hypothesis by generating groundwater level projections using deep learning models for annual, inertial (low-frequency dominated) or mixed annual/low-frequency aquifer types in northern France from 16 CMIP6 climate model inputs in an ensemble approach. Generated projections were then analyzed for trends and changes in variability. Generally, groundwater levels tended to decrease for all types and scenarios across 2030-2100 without any significant differences between emission scenarios. However, when comparing future projections to historical data, groundwater levels appeared slightly higher in the near future (2030-2050), with decreasing intensities in later periods. The variability of projections showed slightly increasing variability for annual types for all scenarios but decreasing variability for mixed and inertial types. As the severity of the scenario increased, more mixed and inertial-type stations appeared to be affected by decreasing variability. Focusing on low-frequency confirmed this observation: while a significant amount of stations showed increasing variability for the less severe SSP2-4.5 scenario, low-frequency variability eventually showed slight yet statistically significant decreasing trends as the severity of the scenario increased. For the most severe scenario, almost all stations were affected by decreasing low-frequency variability
Simulations Euler-Euler pour décrire le transport colloïdal en vue de la remédiation des eaux souterraines
No full textInternational audienceNon-aqueous liquids (NAPLs) are water-immiscible pollutants that can disperse and release significant amounts of toxic compounds into underground water resources. Numerous methods have been developed to remove these pollutants from aquifers, but NAPL droplets remain trapped by capillary forces in the porous matrix even after depollution. The aim of our research is to explore the potential of colloids (e.g. nanoparticles, bacteria) to remobilize immiscible pollutant droplets. Our final objective is to develop a multiphase model that includes colloidal interactions with the solid phase, the aqueous phase, and the NAPL. Euler-Lagrange models allow us an accurate description of colloidal particle interactions (e.g. transport and retention) but remains very time-and resource-intensive. In this work, we are developing Euler-Euler approaches based on OpenFOAM's multiphaseEuler module to represent particles as a dispersed phase in water. The use of this model in the context of the remediation of polluted porous media is currently under development. Our model includes new viscosity models and plastic behavior, as well as the poromechanic properties. We present preliminary results such as: i) comparisons with Euler-Lagrange simulations for very diluted suspension, and ii) response to fluid stresses and its compressibility.Les liquides non aqueux (NAPLs) sont des polluants non miscibles à l'eau qui peuvent se disperser et libérer des quantités importantes de composés toxiques dans les ressources en eau souterraines. De nombreuses méthodes ont été développées pour éliminer ces polluants des aquifères, mais les gouttelettes de NAPL restent piégées par les forces capillaires dans la matrice poreuse, même après la dépollution. Le but de notre recherche est d'explorer le potentiel des colloïdes (par exemple, les nanoparticules, les bactéries) pour remobiliser les gouttelettes de polluants non miscibles. Notre objectif final est de développer un modèle multiphasique qui inclut les interactions des colloïdes avec la phase solide, la phase aqueuse et le NAPL. Les modèles d'Euler-Lagrange nous permettent d'obtenir une description précise des interactions entre les particules colloïdales (par exemple, le transport et la rétention), mais ils nécessitent beaucoup de temps et de ressources numériques. Dans ce travail, nous développons des approches Euler-Euler basées sur le module multiphaseEuler d'OpenFOAM pour représenter les particules comme une phase dispersée dans l'eau. L'utilisation de ce modèle dans le contexte de la remédiation des milieux poreux pollués est actuellement en cours de développement. Notre modèle inclut de nouveaux modèles de viscosité et un comportement plastique, ainsi que les propriétés poromécaniques. Nous présentons des résultats préliminaires tels que : i) des comparaisons avec des simulations d'Euler-Lagrange pour une suspension très diluée, et ii) la réponse aux contraintes du fluide et sa compressibilité