Vertisols cover a hydrologically very significant area of semi-arid regions, and thus understanding of water flow and solute accumulation is very relevant to agricultural activity and water resources management. Previous works suggest a conceptual model of desiccation-crack-induced salinization where salinization of sediment in deep section of the vadose zone (up to 4 m) is induced by subsurface evaporation due to convective air flow in desiccation cracks. This thesis presents a conceptual model of water flow and solute transport in vertisols, and its numerical implementation. The model uses a single-porosity material but unconventionally prescribes a boundary condition representing a deep crack in soil and uses the unsaturated hydraulic conductivity as one of the fitting parameters. The numerical model is bound to one location close to a dairy farm waste pond, but the application of the suggested conceptual model could be possibly extended to all semi-arid regions with vertisols. Simulations were conducted using several modelling approaches with an ultimate goal of fitting the simulation results to the controlling variables measured in the field: water content, and chloride salinity of pore water. The development of the model was engineered in numerous steps; all computed as forward solutions by...

Ce mémoire présente une étude physicochimique sur la réutilisation des fluides de mobilisation pour le traitement de sols contaminés. Cette recherche a été menée afin d’étudier l’efficacité de cette réutilisation et d’évaluer la réduction des coûts opérationnels et des impacts environnementaux. La première partie de ce travail est consacrée au traitement d’hydrocarbures lourds issus de créosote ou de goudrons dans des sols moyennement à fortement contaminés. Plusieurs stratégies ont été développées et évaluées tant pour la réutilisation et l’optimisation d’agents chimiques que pour l’efficacité du fluide de lavage. L’étude du mécanisme d’oxydation des hydrocarbures avec du persulfate a permis d’entrevoir la possibilité de réactions en cascades. Les procédés membranaires d’ultra- et de nano-filtration se sont révélés particulièrement attractifs car préservant l’activité des fluides de traitement après utilisation; Des mesures ont permis d’optimiser à la fois la récupération des substances actives et l’abattement des contaminants. L’étude du mécanisme de mobilisation des hydrocarbures par des mousses de surfactant a montré que les hydrocarbures lourds sont majoritairement extraits dans la phase gazeuse de l’émulsion eau-air. Ces différentes stratégies ont été évaluées au cours de campagnes de terrain. La deuxième partie concerne la réutilisation de solutions diluées d’agents chélatants pour extraire, puis immobiliser des cations métalliques divalents. Plusieurs agents chélatants de la famille des polyaminocarboxylates ont été évalués. La régénération des ligands à partir de résines chélatantes ou de FeS a été évaluée à travers de nombreux cycles de réutilisation / This thesis presents a physico-chemical study devoted to the reuse of remediation fluids for contaminated soil treatment. The aim of this research project was to study the reuse efficiency and to evaluate the reduction of operational costs and environmental impacts. The first part was focused on the treatment of moderately to highly contaminated soils by heavy hydrocarbons from creosote or tar. Several strategies have been developed and evaluated for reuse and optimization of chemical agents. The oxidation mechanism of hydrocarbons with persulphate highlights possible cascade reactions. Ultra- and nanofiltration processes were particularly attractive for activity safe of used treatment fluids; Measurements have been optimized for both active substances recovery and contaminants reduction. The study of hydrocarbons mobilization mechanism by surfactant foams showed that the heavier hydrocarbons are mainly extracted into gaseous phase of water-air emulsion. The different strategies were evaluated during field campaigns. The second part deals with the reuse of chelating agents dilute solutions to extract and then immobilize divalent metal cations. Several chelating agents of polyaminocarboxylates family were evaluated. Regeneration of ligands from chelating resins or FeS was evaluated for many reuse cycles.

Le réchauffement climatique est lié aux augmentations des concentrations de gaz à effet de serre dans l'atmosphère terrestre et en particulier aux émissions anthropiques de CO₂. La séquestration géologique a la capacité et la longévité potentielles pour diminuer de façon significative les émissions anthropiques de CO₂. Cette séquestration à grande profondeur induit des risques de fuite des réservoirs géologiques. Parmi les scénarios de fuite envisagés, celui d'une fuite diffuse est le plus inquiétant puisque sans surveillance, cette fuite pourrait perdurer et entrainer des séquelles sur l'environnement ainsi que des risques pour les populations. Des outils et protocoles de surveillance doivent donc être mis au point pour la surveillance en proche surface. Ce travail de thèse s'inscrit dans le cadre de cette problématique. Il a pour objectif la caractérisation, la quantification et la modélisation du transport et des interactions du CO₂ dans une zone non saturée carbonatée. Ce travail a suivi une approche expérimentale sur un site pilote naturel à Saint-Emilion (Gironde, France), avec la réalisation de fuites diffuses en ZNS carbonatée. Cette étude aborde plusieurs thématiques: la description et l'instrumentation du site pilote naturel ; la caractérisation physico-chimique de l'hétérogénéité du réservoir carbonaté ; l'étude du fonctionnement naturel de la ZNS carbonatée et en particulier la mise en place d'une ligne de base des concentrations en CO₂ ; la caractérisation de l'extension des panaches de gaz suite à des expériences de fuite diffuse dans la ZNS carbonatée et l'étude par simulation numérique des interactions gaz-eau-roche lors d'une fuite diffuse de CO₂ dans une ZNS carbonatée. Les résultats de ces travaux montrent l'importance de la caractérisation de l'hétérogénéité du réservoir carbonaté ainsi que des techniques d'échantillonnage et d'analyse des différentes phases en présence. L'établissement de la ligne de base a une importance particulière pour permettre de distinguer les variations naturelles de celles induites par une fuite diffuse de CO₂ dans la ZNS carbonatée. Les modes de transport du CO₂ vont évoluer en fonction des paramètres physico-chimiques. Ce transport se fait par advection et/ou par diffusion. L'utilisation de gaz inertes au niveau du site de séquestration géologique est très importante puisque la détection de ces traceurs permettrait de prédire les arrivées de panaches de CO₂ en proche surface. Par ailleurs, les interactions chimiques doivent être prises en compte dans les modèles de transport afin de pouvoir définir les facteurs de retard et l'impact d'une fuite diffuse de CO₂ sur une ZNS carbonatée. / Global warming is related to atmospheric greenhouse gas concentration increase and especially anthropogenic CO₂ emissions. Geologic sequestration has the potential capacity and the longevity to significantly diminish anthropogenic CO₂ emissions. This sequestration in deep geological formation induces leakage risks from the geological reservoir. Several leakage scenarios have been imagined. Since it could continue for a long period, inducing environmental issues and risks for human, the scenario of a diffusive leakage is the most worrying. Thus, monitoring tools and protocols are needed to set up a near-surface monitoring plan. The present thesis deals with this problematic. The aims are the characterisation, the quantification and the modelling of transport and interactions of CO₂ in a carbonate unsaturated zone. This was achieved following an experimental approach on a natural pilot site in Saint-Emilion (Gironde, France), where diffusive gas leakage experiments were set up in a carbonate unsaturated zone. Different aspects were investigated during the study: natural pilot site description and instrumentation; the physical and chemical characterisation of carbonate reservoir heterogeneity; the natural functioning of the carbonate unsaturated zone and especially the set-up of a CO₂ concentrations baseline; the characterisation of gas plume extension following induced diffusive leakage in the carbonate unsaturated zone and the study of gas-water-rock interactions during a CO₂ diffusive leakage in a carbonate unsaturated zone through numerical simulations. The results show the importance of the carbonate reservoir heterogeneity characterisation as well as the sampling and analysing methods for the different phases. The baseline set-up is of main interest since it allows discrimination between the induced and the natural CO₂ concentrations variations. The transfer of CO₂ in a carbonate unsaturated zone is varying in function of physical and chemical properties. This transfer is done by diffusion and/or advection. Because the detection of the noble gases allows the prediction of CO₂ plume arrival, the use of tracers in the sequestration site is of main importance. The chemical interactions have to be taken under account in transport models in order to predict delay factors and the impact of a CO₂ leakage in a carbonate unsaturated zone.

The main objective of this study is to develop a modeling methodology that facilitates incorporating the plant pathway into environmental contamination models recognizing the fact that plants are dynamic entities that regulate their life cycle according to natural and anthropogenic environmental conditions. A modeling framework that incorporates the plant pathway into an integrated water flow and contaminant transport model in terrestrial systems is developed. The modeling framework is aimed to provide a tool to analyze the plant pathway of exposure to contaminants. The model developed using this framework describes the temporal and spatial variation of the contaminant concentration within the plant as it is interacting with the soil and the atmosphere. The first part of the study focuses on the integration of the dynamics of water and contaminant distribution and plant related processes within the vadose zone. A soil-plant system model is developed by coupling soil-water flow, contaminant transport, plant life-cycle, and plant pathway models. The outcome unifies single media continuous models with multimedia compartmental models in a flexible framework. The coupling of the models was established at multiple interfaces and at different levels of solution steps (i.e. model development phase vs. numerical solution phase). In the second part of the study, the soil-plant system model is extended to cover large spatial areas by describing the environmental system as a collection of soil-plant systems connected through overland flow and transport processes on the ground surface and through lateral interactions in the subsurface. An overland flow model is integrated with the previously coupled model of unsaturated zone soil-water flow and plant life-cycle by solving the flow model equations simultaneously within a single global matrix structure. An overland / subsurface interaction algorithm is developed to handle the ground surface conditions. The simultaneous solution, single-matrix approach is also adopted when integrating the overland transport model with the previously coupled models of vadose zone transport and plant pathway. The model developed is applied to various environmental contamination scenarios where the effect of the presence of plants on the contaminant migration within environmental systems is investigated.

Les particules mobiles du sol peuvent transporter des polluants vers la nappe phréatique. Dans les crassiers sidérurgiques, les éléments métalliques lixiviés contribuent à une contamination rapide des eaux du sol. L’objectif de ce travail est de comprendre les mécanismes qui interviennent dans le transport en solution et sous forme particulaire dans des déchets sidérurgiques stockés sur le long terme. Pour ce faire, une caractérisation complète des compositions minéralogiques et chimiques a été effectuée. Elle révèle que ces déchets sont constitués de minéraux de haute température typiques des laitiers et de minéraux d’altération météorique. Les eaux de percolation montrent des pH élevés, dus à des teneurs élevées en calcium, et des teneurs importantes en aluminium et silicium. Les teneurs en chrome et molybdène, et ponctuellement en vanadium sont élevées dans les lixiviats des laitiers de fusion. L’analyse granulométrique des particules mobilisées, pour des pluies simulées en colonne, indique que leur taille moyenne est de 200 µm, ce qui laisse prévoir une faible mobilité dans les formations sous-jacentes moins perméables. Les calculs de spéciation montrent que les lixiviats sont saturés ou proches de l'équilibre vis-à-vis des silicates calciques hydratés et souvent saturés en molybdate de calcium. / Mobile soil particles can transport pollutants to groundwater. In slag heaps, leached metallic elements contribute to soil water contamination. The aim of this work is to identify the role of slag particles in contaminant transport under unsaturated and saturated conditions. Mineralogical compositions and physicochemical properties of slags are first determined. The analysis show high temperature slag phases and weathering phases. Percolation tests are also carried out in repacked waste columns under infiltration/drying cycles to find out the effects of dry periods on in situ particle mobilization. Preferential flows lead to rapid transport of solute through the repacked column in vadose zone. Leachates are characterized by high pH and high concentrations of calcium, aluminum and silicon, molybdenum, chromium in the fusion slags. Speciation calculations showed that the leachates are saturated in calcium silicate hydrates. Laser size analyzer shows that the slag particles mobilized during the simulated rain events are around 200 µm, which suggests low mobility in the less permeable underlying formations.

Water in porous rocks (e.g. sandstone) plays a fundamental role in their disintegration. However, the places where water enters the sandstone rocks are somewhat overlooked. At two sites in the Český ráj region, I use Karsten tube to measure capillary water absorption (CWA) of natural sandstone exposures and, using TDR (Time Domain Reflectometry) method, I study movement of water in a shallow zone of ruiniform sandstone landscape. The CWA differed up to four orders of magnitude at a distance of tens of meters, mostly depending on the type of the surface. The highest CWA was measured at highly weathered surfaces, the second most absorbent were less weathered surfaces covered with a biologically-initiated rock crust. The horizontal surfaces on the tops of the rock formations were even less absorbent, probably due to clogging by fine particles from soil. Surfaces covered with iron crust were the least absorbent. The differences between those surfaces are significant. After simulated infiltration, the maximum rate of the propagation of the wet front in the sandstone was from 5,5.10-6 do 1,9.10-4 m.s-1 measured by TDR. The water propagated at this rate only to a certain depth (the first tens of cm), but then the propagation stopped or slowed down rapidly. From a long-term measurement of volumetric...

The increasing commercial and industrial use of ethanol, i.e., in biofuel and gasoline, has generated increased incidents of vadose zone contamination by way of ethanol spills and releases. This has increased the interest in better understanding infiltration behaviours of ethanol in unsaturated porous media and the multiphase interactions in the vadose zone. Solute-dependent capillarity-induced focused flow (SCIFF) is a vertical, highly focused flow infiltration behaviour first reported by Smith et al. (2011) in butanol-contaminated sands. Through the use of highly controlled laboratory experiments, this thesis research investigates focused flow (SCIFF) and related behaviours through water infiltration into ethanol-contaminated unsaturated sand. Focused flow behaviours (SCIFF) were demonstrated through the infiltration of water into an ethanol-contaminated unsaturated sand using both constant flux and constant head methodologies. The observation of focused flow behaviours in ethanol-contaminated sand supported the primary hypothesis of this work. The secondary hypothesis was also supported, as focused flow behaviours were not observed, rather stable semicircular infiltration patterns were observed during ethanol infiltration into water-wet sand. Comparisons between constant flux and constant head application methods under similar flow rates and fluid volumes produced similar results. The zone of lower saturation, or the “halo effect” reported in previous literature, was strongly expressed during water infiltration in ethanol-contaminated sand. This halo effect is affected by the maximum (at 40% to 50%) of aqueous concentration of ethanol. This maximum enhances the zone of lower saturation and stabilizes the solute front. The SCIFF focused flow also overcame the effects of minor heterogeneities in the sand. However, additional laboratory and modelling work is required to further understand the extent of SCIFF behaviour. / Thesis / Master of Science (MSc) / Understanding the behaviour and interaction of water and contaminants in soils is important as environmental contamination and spills can have devastating environmental impacts. In recent decades, ethanol spills and accidental releases onto ground surface have increased as the commercial and industrial use of ethanol has increased. The goals of this work were to qualitatively visualize and quantify the unique nature of water infiltration into the ethanol-contaminated soil and understand the complex mechanisms behind water-ethanol interactions. This research showed that water infiltration creates an uncommon vertical, focused pattern when flowing into sand contaminated by ethanol. However, when ethanol is applied to standard water-wet sand, that behaviour is not observed. This work provided greater insight into the nature of ethanol-contaminated soils. These findings furthered the understanding needed to evaluate impacts that ethanol contamination can have on remedial efforts and the rate of migration of contaminants to groundwater.

Le stockage géologique du carbone est l’une des techniques les plus prometteuses pour réduire le taux de CO₂ dans l’atmosphère. La séquestration géologique possède la capacité et la longévité potentielles pour diminuer les émissions de CO₂ vers l’atmosphère. Dans le cadre d’injections à l’échelle industrielle, les réservoirs carbonatés peuvent faire partie des sites aptes à stocker du CO₂. Toutefois, ces injections à grandes profondeurs sont sujettes à des risques de fuites du piège géologique lui-même ou des infrastructures liés à l’exploitation du site de stockage. Ainsi, il existe principalement deux types de fuite : brutale et diffuse. Dans les deux cas, elles sont susceptibles d’entrainer des risques pour l’environnement et de mettre en danger les populations. Il est ainsi nécessaire de développer des outils capables de prévenir une fuite de CO₂ quel que soit son type. Par ailleurs, il est particulièrement indispensable de comprendre les mécanismes de transport réactif qui rentrent en jeu lors de l’arrivée de cette fuite en contexte de proche surface (zone vadose) et ainsi d’essayer d’étudier comment cette fuite peut s’amortir. Ces travaux de thèse traitent donc de la caractérisation, de la quantification et de la modélisation des processus de transferts et des interactions CO₂-H₂O-CaCO₃ dans la zone vadose en contexte de fuite à partir d’un puits de forage. Cette problématique a été d’abord abordée par une approche expérimentale sur un site pilote à Saint-Emilion. Puis, les interactions CO₂-H₂O-CaCO₃ ont été étudiées au travers d’une approche expérimentale à l’échelle de la carotte en laboratoire. L’approche expérimentale a conduit à la réalisation de deux fuites dans la zone vadose du site pilote : une fuite diffuse et une fuite ultra diffuse. Elles furent réalisées dans la continuité des expériences qui avaient déjà eu lieu auparavant. Une comparaison de l’ensemble des fuites a montré la nécessité d’utiliser des gaz nobles comme précurseurs de l’arrivée en surface du CO₂. Selon le type de fuite, l’hélium peut servir de précurseur temporel du CO₂, tandis que le krypton prévient de l’étendue du panache de gaz durant la fuite. Plus la pression d’injection du CO₂ est importante et plus le gaz migre par advection. Par ailleurs, une pression d’injection importante favorise l’existence de passage préférentiel dans la zone vadose. L’utilisation d’isotopes tels que ceux de l’hélium et du carbone permet de mettre en évidence la présence locale de phases aqueuses dans le massif et de déterminer l’origine biologique ou anthropique du CO₂. Les expériences à l’échelle de la carotte permettent d’estimer le pouvoir tampon des calcaires oligocènes en fonction du faciès de la roche. La perméabilité et la porosité de celle-ci conditionnent la dissolution des calcaires. De même, la réactivité des carbonates en contexte de fuite dépend du pH de la phase aqueuse, du débit qui traverse le réseau poreux, de la saturation en eau et des caractéristiques pétro-physiques des carbonates. / Carbon storage is one of the most encouraging methods to decrease CO₂ concentration into the atmosphere. Carbon storage provides the longevity and the capacity needed to decrease CO₂ emissions toward the atmosphere. When dealing with storage on an industrial scale, carbonated reservoirs can be among the most suitable storage sites. However, these high depth injections are subject to leakage risks from the geologic trap itself or from the framework created by the establishment of the site. Two main types of leakage exist: brutal and diffusive leakage. In both cases, they are likely to endanger the environment and the population. Therefore, it is essential to develop tools that are able to anticipate any types of CO₂ leakage. Furthermore, it is also necessary to understand the reactive transport mechanism that take place when the leakage arrives in the shallow subsurface (vadose zone)and to see how the leakage can be buffered. This work deals with the characterization, the quantification and the modelling of transfer processes and CO₂-H₂O-CaCO₃ interactions into the vadose zone in a context of a leakage from a drilling well. This issue was first dealt through field experiment on the site of Saint Emilion. Then, the CO₂-H₂O-CaCO₃ interactions were studied through an experimental approach in laboratory. Two leakage experiments were performed on the site: a diffusive leakage and an ultra-diffusive leakage. They were performed as a sequel of former experiments carried on the pilot site. A comparison of all the leakage experiments revealed the necessity to use noble gases as precursor of the CO₂ arrival at the surface. Depending of the type of the leakage, helium can be a temporal precursor while krypton can anticipate the spread of the CO₂ gas plume. The higher the injection pressure, the more the gas migrates through advective flux. Moreover, a high injection pressure favors the existence of preferential paths in the vadose zone. The use of helium and carbon isotopes makes it possible to reveal the presence of a local aqueous phase within the porous media and to identify the origin of CO₂. The core scale experiments lead to the estimation of the buffering power of Oligocene limestone according to the rock facies. The permeability and the porosity influence the dissolution of the limestone. The reactivity of carbonates during a leakage depends on the pH of the aqueous phase, the flow rate that goes through the porous media, the water saturation and petrophysical characteristics of the carbonates.

Les bassins d’infiltration font partie intégrante des techniques alternatives de gestion des eaux pluviales en milieu urbain. Néanmoins, la potentialité de transfert de polluants vers la nappe est accrue en cas d’écoulements préférentiels dans les sols sous-jacents. Une bonne compréhension du couplage entre processus d’écoulements préférentiels en zone vadose et mécanismes géochimiques est requise. Cette thèse s’inscrit dans le cadre du suivi d’un bassin d’infiltration depuis plusieurs dizaines d’années de fonctionnement. Le site d’étude est situé sur le dépôt fluvioglaciaire hétérogène couvrant une grande partie de la région lyonnaise. Des auscultations sur une fosse sous le bassin (section 13.5m*2.5m) ont mis en évidence une régionalisation particulière de la pollution dans le sol. Cette étude s’appuie sur une étude numérique visant à identifier l’origine de la régionalisation des polluants et à la relier aux écoulements préférentiels résultant des hétérogénéités lithologiques. En amont de l’étude numérique, les lithofaciès sont complètement caractérisés aux regards de leurs propriétés hydrodynamiques, hydrodispersives et géochimiques. La modélisation numérique permet de souligner l’établissement de cheminements préférentiels en lien avec le contraste de propriétés hydrodynamiques, notamment lorsque de faibles débits sont appliqués en surface. Le rôle de chaque lithofaciès et de l’architecture du dépôt (stratification et inclusions) est clairement identifié. Les répercussions de tels écoulements sur les transferts non réactifs sont ensuite investiguées en combinant l’influence des écoulements préférentiels et le fractionnement de l’eau en fractions mobile et immobile résultant de l’hétérogénéité intrinsèque au sein de chaque lithofaciès. Enfin, ces processus physiques sont couplés à la réactivité géochimique pour le cas d’un polluant modèle (le cuivre) en prenant en compte la réactivité différentielle des lithofaciès. Ces résultats permettent de générer un modèle conceptuel d’écoulements préférentiels et de transfert de masse en milieu fortement hétérogène. / An infiltration basin is a stormwater best management practice (BMP) designed to infiltrate runoff volumes in urban areas. Nevertheless, preferential flow paths in the underlying soil may cause rapid migration of pollutants, thus contributing to groundwater contamination. Understanding the coupling between preferential flow processes in the vadose zone and geochemical mechanisms is then required. This thesis is a part of the follow-up of an infiltration basin for several decades of exploitation. The study site was settled over a highly heterogeneous glaciofluvial deposit covering much of the Lyon region. The investigation of an excavated section of the basin (13.5m long and 2.5m deep) pointed out a specific regionalization of pollution in the soil. This research is based on a numerical study to identify the origin of such a pollutant pattern and link this with preferential flow resulting from lithological heterogeneities. Different lithofacies were fully characterized regarding their hydraulic, hydrodispersive and geochemical properties. The numerical study proves that the high contrast in hydraulic properties triggers the establishment of preferential flow (capillary barriers and funneled flow). Preferential flow develops mainly for low initial water contents and low fluxes imposed at surface. The role of each lithofacies and architecture of deposit (stratification and inclusions) is clearly identified. The impact of such flows on non-reactive transfers is then investigated by combining the influence of preferential flow and pore water fractionation info into mobile and immobile fractions, resulting from the intrinsic heterogeneity within each lithofacies. Finally, these physical processes are coupled to the geochemical reactivity for a pollutant model (copper), taking into account the differential reactivity of lithofacies. These results generate a conceptual model of preferential flow and mass transfer in strongly heterogeneous media.

La compréhension des écoulements préférentiels dans la zone non saturée en fond de bassins d’infiltration est une condition préalable à une gestion optimale de ces ouvrages. Le basin d’infiltration étudié repose sur un dépôt fluvioglaciaire hétérogène constitué d’un lithofaciès majoritaire contenant des lentilles de sable et de gravier. Une étude géophysique (radar) a permis de caractériser cette hétérogénéité sédimentologique le long de radar-grammes (sections de quelques mètres de profondeurs et de plusieurs dizaines de mètre de long). Les écoulements ont été modélisés pour toutes ces sections ainsi qu’une section fictive remplie uniquement du lithofaciès majoritaire (témoin) et pour divers évènements pluvieux type incluant une chronique météorologique complète. Les résultats montrent clairement que l'hétérogénéité lithologique a un effet significatif sur l’écoulement avec la mise en place d’écoulements hétérogènes du fait de phénomènes de barrière capillaire au niveau des lentilles de sable et de gravier en non-saturé. Cet effet se répercute sur les chemins de l’eau dans le dépôt et sur les flux en surface (infiltration et ruissellement). Les résultats montrent aussi que cet effet dépend fortement de la section considérée. La variabilité spatiale de l’hétérogénéité lithologique induit donc une variabilité spatiale des écoulements préférentiels. Certains paramètres architecturaux et géométriques relatifs à l’hétérogénéité lithologique ont été proposés pour expliquer l’effet de l’hétérogénéité lithologique sur les écoulements préférentiels, de sorte à proposer une première tentative de modélisation des écoulements à méso-échelle. / Understanding preferential flows in the vadose zone is a prerequisite for a proper management of infiltration basins. The studied infiltration basin lies on a strongly heterogeneous glaciofluvial deposit made of a predominant lithofacies that embeds lenses of sand and gravel. Geophysics (GPR) were used to characterize the lithological heterogeneity along radar-grammes (sections few meters deep and dozens of meters long). Flow was modelled for all these sections and compared to a synthetic section filled only with the predominant lithofacies (control). Numerical results show that, under unsaturated conditions, the lithological heterogeneity has a strong impact on flow with the establishment of preferential flows induced by capillary-barrier effects in the vicinity of lenses of sand and gravel. These effects have also consequences on water fluxes at surface (infiltration and runoff) and depend strongly on the section considered for numerical modelling. It can thus be concluded that the spatial variability of lithological heterogeneity induces a spatial variability of preferential flow. Geometrical and architectural parameters were defined to quantity lithological heterogeneity and link it to preferential flows, with the aim to propose a first step towards modelling flow in the basin at the meso-scale. / O entendimento do fluxo na zona não saturada em formações heterogêneas é um prérequisito para uma gestão adequada de poluentes em bacias de infiltração inseridas nessas formações. Este estudo aborda o efeito da heterogeneidade litológica nos processo de escoamento numa bacia de infiltração com geologia inserida num depósito fluvioglacial. A bacia de infiltração é a Bacia Django Reinhardt, existente em Lyon. Esta bacia foi objeto de vários estudos que demonstraram algumas avaliações do impacto da heterogeneidade do solo. Os objetivos desses trabalhos foram todos baseados apenas no estudo sedimentológico de uma trincheira. Nenhum estudo abordou a potencial variabilidade espacial dos atributos do solo. Neste trabalho, foi modelizado o fluxo na zona vadosa através de três casos: drenagem interna, infiltração de água durante um evento de precipitação pluviométrica constante e solicitação hidrológica a partir de um fluxo variável escoamento superficial. Estes cálculos foram realizados para várias seções, que foram previamente caracterizadas quanto a sua heterogeneidade estrutural usando a técnica não destrutiva do GPR com uma frequência de 200MHz e 100MHz. O comportamento hidráulico dessas seções foi comparado com a de uma seção homogênea. Foi comparada o efeito da resolução da imagem nas estimativas das variáveis de fluxo. Alguns indicadores arquiteturais, geométricos e texturais foram propostos para esclarecer e avaliar a variabilidade espacial do efeito da heterogeneidade do solo sobre o fluxo em condições não saturadas. Os resultados mostram claramente que a heterogeneidade gera impactos nas variáveis de fluxo em condições não saturadas. Os impactos dependem da seção considerada.Os resultados mostram também que: a) a heterogeneidade estrutural do subsolo na meso-escala apresenta um efeito sobre a geração de escoamento preferencial e isso independe do tipo de solicitação aplicada na seção; b) O efeito da heterogeneidade se mostrou independentende das condições de contorno aplicadas na superfície; c) Nos períodos de ocorrência de chuvas intensas quem controla o comportamento das variáveis de fluxo é a intensidade de precipitação. No entanto, nos períodos em que ocorre ausência de precipitação, as variáveis de fluxo são controladas pela heterogeneidade da zona não saturada; d) A utilização de diferentes frequências influencia na estimativa das variáveis de fluxo. Isso é decorrente do impacto na quantificação da heterogeneidade decorrente do efeito da resolução de cada antena; e) Os indicadores não apresentaram relação direta com as variáveis de fluxo estudadas. Isso demonstra que o efeito da heterogeneidade não pode ser explicado por um único fator, mas por um conjunto de fatores.