The INRIA-LIM-VocR and AXES submissions to Trecvid 2014 Multimedia Event Detection

-This paper describes our participation to the 2014 edition of the TrecVid Multimedia Event Detection task. Our system is based on a collection of local visual and audio descriptors, which are aggregated to global descriptors, one for each type of low-level descriptor, using Fisher vectors. Besides these features, we use two features based on convolutional networks: one for the visual channel, and one for the audio channel. Additional high-level featuresare extracted using ASR and OCR features. Finally, we used mid-level attribute features based on object and action detectors trained on external datasets. Our two submissions (INRIA-LIM-VocR and AXES) are identical interms of all the components, except for the ASR system that is used. We present an overview of the features andthe classification techniques, and experimentally evaluate our system on TrecVid MED 2011 data

Dataset used in "From lowlands to mountain peaks: impacts of landforms on the desaturation of groundwater-dependent wetlands"

<p>Dataset in the form of text files, all 60 presented catchments are identified by the HydroATLAS database ID in each file. For the seepage distribution, one text file is presented for each catchment named with the corresponding catchment ID. </p&gt

Fault zones properties and groundwater resources in crystalline rocks

International audiencepas de résum

Hydrological behavior of a deep sub-vertical fault in crystalline basement and relationships with surrounding reservoirs

International audienceCrystalline-rock aquifers generally yield limited groundwater resources. However, some highly productive aquifers may be encountered, typically near tectonic discontinuities. In this study, we used a multidisciplinary experimental field approach to investigate the hydrogeological behavior of a sub-vertical permeable fault zone identified by lineament mapping. We particularly focused our investigations on the hydrogeological interactions with neighboring reservoirs. The geometry of the permeable domains was identified from geological information and hydraulic test interpretations. The system was characterized under natural conditions and during a 9-week large-scale pumping test. We used a combination of piezometric analysis, flow logs, groundwater dating and tracer tests to describe the interactions between permeable domains and the general hydrodynamical behaviors. A clear vertical compartmentalization and a strong spatial heterogeneity of permeability are highlighted. Under ambient conditions, the vertical permeable fault zone allows discharge of deep groundwater flows within the superficial permeable domain. The estimated flow across the total length of the fault zone ranged from 170 to 200 m3/day. Under pumping conditions, hydrological data and groundwater dating clearly indicated a flow inversion. The fault zone appears to be highly dependent on the surrounding reservoirs which mainly ensure its recharge. Groundwater fluxes were estimated from tracer tests interpretation. This study demonstrates the hydrogeological capacities of a sub-vertical fault aquifer in a crystalline context. By describing the hydrological behavior of a fault zone, this study provides important constrain about groundwater management and protection of such resources

Geomorphological controls on groundwater transit times:a synthetic analysis at the hillslope scale

International audienceWe investigated how geomorphological structures shape Transit Time Distributions (TTDs) in shallow aquifers. Extensive 3D simulations were performed to determine the TTDs for synthetic convergent, straight and divergent hillslopes with a constant slope. The uniform recharge applied on top of the aquifer is transferred to the receiving stream through steady-state groundwater flows, return flows and saturation excess overland flows. Without seepage, TTDs evolve from uniform- to power law-like- distributions depending on the average distance of the groundwater volume to the river (barycenter). Remarkably, the coefficient of variation (ratio of the standard deviation to the mean) of the TTDs scales linearly with the barycenter in agreement with a theoretical prediction based on three analytical approximations derived for specific cases. With seepage, the TTD has three separate modes corresponding to rapid saturation excess overland flows, to the intermediate flow paths ending in seepage area and to the slower flow paths going all the way to a discharge in the river. The coefficient of variation additionally depends on the extent of the seepage area. For a natural hillslope in the crystalline basement of Normandy (France), the same synthetic analysis demonstrates that the coefficient of variation is not only determined by the extent of the seepage zone but also by its structure in relation to the local and global geomorphological organization. The results suggest the possibility to assess the variability of transit times by combining geomorphological analysis, surface soil saturation observations and environmental tracers

How geomorphology shapes groundwater transit times at the hillslope scale?

International audienceWe investigate how geomorphological structures shape Transit Time Distributions (TTDs) in shallow aquifers. We show that the TTD is determined by integrated features of the groundwater structure and of the repartition of seepage in convergent/divergent hillslopes of constant slope. More specifically, the coefficient of variation of the TTD (standard deviation divided by the mean) scales linearly with the mean distance of the groundwater volume to the river. The extent and structure of seepage modify the groundwater contribution to the transit time distribution and increase its variability.Extensive 3D simulations were performed to determine the TTDs synthetic convergent, straight and divergent hillslope models of constant slope. The recharge was applied uniformly on top of the aquifer and transferred to the receiving stream through steady-state groundwater flows, return flows and saturation excess overland flows. Without seepage, TTDs evolve from uniform- to power law-like- distributions depending on the average distance of the groundwater volume to the river. Remarkably, the coefficient of variation of the TTDs scales linearly with the groundwater volume to the river at any hillslope convergent/divergent rate in agreement with a theoretical prediction based on three analytical approximations. With seepage, the TTD progressively displays three separate modes corresponding (1) to the rapid saturation excess overland flows, (2) to the intermediary circulations ending up in seepage area and (3) to the slower circulations going from a recharge upstream the seepage zone to a discharge in the river. The coefficient of variation additionally depends on the extent of the seepage area.Applied to a natural hillslope in the crystalline basement of Normandy (France), the same synthetic analysis demonstrates that the coefficient of variation is not only determined by the extent of the seepage zone but also by its structure in relation to the geomorphological local and global organizations. These results suggest the possibility to assess the variability of transit times by combining geomorphological analysis, surface soil saturation observations and environmental tracers

Geomorphological Controls on Stream Baseflow Recession

International audienceThe understanding of the physical processes controlling water fluxes from hillslope aquifers to surface waters is critically needed for predicting stream discharge and establishing sustainable water resources management strategies. Two major hypotheses are currently being debated: the first considers that climate, stream network morphology and topography have a first-order control on groundwater flow and stream recession. Thus the prediction of stream baseflow can be approximated by considering idealized homogeneous groundwater reservoirs with effective properties. The second hypothesis suggests that the structural heterogeneity of the landscape (lithological variations, geological discontinuities, spatial distribution of topographic and tectonic stresses) might significantly control the partitioning of water within the landscape, and in turn impact how streamflow recession behaves.In this contribution we provide a comprehensive analysis of stream discharge and geomorphological databases across various geological domains distributed throughout the globe in order to identify the main factors that might influence recession constants at baseflow. A novel computational approach for single recession analysis revealed that recession constants might strongly deviate from what is predicted from idealized theories, with power law recession constants ranging from 1.5 to more than 10. A correlation analysis allows us to identify the control of key features of the landscape on groundwater storage and streamflow recession constants, with depth to bedrock, lithology and maturity - i.e. degree of weathering and fracturing - of the landscape being the main drivers. We tested these observations through a numerical modelling framework which allowed us to quantify the variability of streamflow recession behaviors raising from the drainage of hillslopes with different structural and geometrical properties. We identify the respective roles of hydraulic conductivity contrasts between the upper and lower compartments, the depth of the shallower compartment and the steepness of the slope on streamflow recession parameters. We finally discuss the implications of these findings in establishing future strategies for the improvement of groundwater storage and stream discharge predictions

HydroModPy: Une application python pour automatiser le déploiement des modèles de bassin versant à grande échelle

International audienceModéliser à l'échelle régionale les circulations souterraines de proche subsurface dans des aquifères superficiels de faibles profondeurs (10-100 m) continuent à se confronter à des enjeux autant hydrologiques que numériques. Les circulations de proche subsurface sont intermédiaires entre l'hydrologie et l'hydrogéologie. Comme en hydrologie, les circulations sont très majoritairement confinées aux versants et en suivent la structure. Les temps de réponse et de transfert sont en revanche plus longs et résultent de processus hydrogéologiques. Les variations de recharge et les battements de nappe induisent également des changements fréquents dans la répartition entre les écoulements en souterrain et en surface. C'est le cas notamment dans des régions de socle cristallin comme dans le Massif Armoricain et le Massif Central où les faibles volumes d'aquifère alliés au climat tempéré produit de fortes interactions des nappes avec la surface à l'échelle caractéristique des versants qui s'échelonne entre quelques km2 et quelques dizaines de km2.     Nous proposons une application développée en Python sous la forme de boite à outils pour modéliser et déployer aussi automatiquement que possible des modèles de bassins versants pour des aquifères libres en forte interaction avec la surface. Cette application, nommée HydroModPy, relie les fonctionnalités de traitement de Modèle Numérique de Terrain (MNT) du logiciel WhiteBoxTool avec les capacités de modélisation des écoulements souterrains et de transport des logiciels Modflow et Modpath via l'interface Python Flopy. Elle est conçue de façon à ce que plusieurs solveurs d'écoulements souterrains soient facilement interchangeables. Elle propose plusieurs options de construction de modèles et de déploiement à partir d'un MNT à l'échelle régionale et d'un exutoire de bassin versant. D'autres options sont en cours de développement pour la calibration à partir de données de niveau piézométrique, de débit en rivière,de localisation du réseau hydrographique, ou encore de traceurs géochimiques. Les atouts de cette approche de modélisation sont de regrouper des projets de modélisation sur des sites différents dans le même environnement en factorisant le développement, d'offrir des capacités de modélisation des aquifère de proche de subsurface et de préparer leur extension à des échelles régionales.

HydroModPy: Une application python pour automatiser le déploiement des modèles de bassin versant à grande échelle

International audienceModéliser à l'échelle régionale les circulations souterraines de proche subsurface dans des aquifères superficiels de faibles profondeurs (10-100 m) continuent à se confronter à des enjeux autant hydrologiques que numériques. Les circulations de proche subsurface sont intermédiaires entre l'hydrologie et l'hydrogéologie. Comme en hydrologie, les circulations sont très majoritairement confinées aux versants et en suivent la structure. Les temps de réponse et de transfert sont en revanche plus longs et résultent de processus hydrogéologiques. Les variations de recharge et les battements de nappe induisent également des changements fréquents dans la répartition entre les écoulements en souterrain et en surface. C'est le cas notamment dans des régions de socle cristallin comme dans le Massif Armoricain et le Massif Central où les faibles volumes d'aquifère alliés au climat tempéré produit de fortes interactions des nappes avec la surface à l'échelle caractéristique des versants qui s'échelonne entre quelques km2 et quelques dizaines de km2.     Nous proposons une application développée en Python sous la forme de boite à outils pour modéliser et déployer aussi automatiquement que possible des modèles de bassins versants pour des aquifères libres en forte interaction avec la surface. Cette application, nommée HydroModPy, relie les fonctionnalités de traitement de Modèle Numérique de Terrain (MNT) du logiciel WhiteBoxTool avec les capacités de modélisation des écoulements souterrains et de transport des logiciels Modflow et Modpath via l'interface Python Flopy. Elle est conçue de façon à ce que plusieurs solveurs d'écoulements souterrains soient facilement interchangeables. Elle propose plusieurs options de construction de modèles et de déploiement à partir d'un MNT à l'échelle régionale et d'un exutoire de bassin versant. D'autres options sont en cours de développement pour la calibration à partir de données de niveau piézométrique, de débit en rivière,de localisation du réseau hydrographique, ou encore de traceurs géochimiques. Les atouts de cette approche de modélisation sont de regrouper des projets de modélisation sur des sites différents dans le même environnement en factorisant le développement, d'offrir des capacités de modélisation des aquifère de proche de subsurface et de préparer leur extension à des échelles régionales.

Characterization of fluxes between deep and surface compartment assessing through groundwater ages

International audienc