Marijke Huysmans

Application of Multiple-Point Geostatistics on Modelling Groundwater Flow and Transport in a Cross-Bedded Aquifer

Sedimentological processes often result in complex three-dimensional subsurface heterogeneity of hydrogeological parameter values. Variogram-based stochastic approaches are often not able to describe heterogeneity in such complex geological environments. This work shows how multiple-point geostatistics can be applied in a realistic hydrogeological application to determine the impact of complex geological heterogeneity on groundwater flow and transport. The approach is applied to a real aquifer in Belgium that exhibits a complex sedimentary heterogeneity and anisotropy. A training image is constructed based on geological and hydrogeological field data. Multiple-point statistics are borrowed from this training image to simulate hydrofacies occurrence, while intrafacies permeability variability is simulated using conventional variogram-based geostatistical methods. The simulated hydraulic conductivity realizations are used as input to a groundwater flow and transport model to investigate the effect of small-scale sedimentary heterogeneity on contaminant plume migration. Results show that small-scale sedimentary heterogeneity has a significant effect on contaminant transport in the studied aquifer. The uncertainty on the spatial facies distribution and intrafacies hydraulic conductivity distribution results in a significant uncertainty on the calculated concentration distribution. Comparison with standard variogram-based techniques shows that multiple-point geostatistics allow better reproduction of irregularly shaped low-permeability clay drapes that influence solute transport.RésuméLes processus de sédimentation génèrent fréquemment des hétérogénéités tridimensionnelles dans les paramètres hydrogéologiques en subsurface. Les approches stochastiques basées sur des variogrammes ne sont souvent pas en mesure de décrire cette hétérogénéité de manière satisfaisante dans des environnements géologiques si complexes. La présente étude expose comment des analyses géostatistiques à points multiples peuvent être mises en œuvre pour une application hydrogéologique réaliste, afin de déterminer l’impact des hétérogénéités géologiques complexes sur l’écoulement et le transport souterrains. Cette approche est mise en application sur un aquifère de Belgique, qui démontre une hétérogénéité sédimentaire et une anisotropie complexes. Une image expérimentale est construite sur la base des données géologiques et hydrogéologiques de terrain. Les statistiques à points multiples sont empruntées à cette image afin de simuler l’occurrence des faciès perméables, tandis que la variabilité de la perméabilité entre les faciès est simulée en utilisant les méthodes géostatistiques standard, basées sur les variogrammes. Les transmissivités simulées sont utilisées comme données entrantes dans un modèle d’écoulement et de transport souterrain, afin de simuler l’effet des hétérogénéités sédimentaires à petite échelle sur la migration d’un panache de polluant. Les résultats montrent que les hétérogénéités à petite échelle ont un effet significatif sur le transport de polluant dans l’aquifère étudié. L’incertitude sur la distribution spatiale des faciès et des transmissivités intrafaciès génère une incertitude significative sur la distribution calculée des concentrations. La comparaison avec les techniques standard basées sur les variogrammes démontre que les analyses géostatistiques à points multiples permettent une reproduction plus fidèle des horizons argileux peu perméables et discontinus qui influencent le transport de solutés.ResumenLos procesos sedimentológicos a menudo dan como resultado heterogeneidad tridimensional compleja en el subsuelo de los valores de los parámetros hidrogeológicos. Aproximaciones estocásticas basadas en variogramas no son a menudo capaces de describir la heterogeneidad en tales ambientes geológicos complejos. Este trabajo muestra de que manera la geoestadística de múltiples puntos puede ser aplicada en una aplicación realista para determinar el impacto de una heterogeneidad geológica compleja en el flujo y transporte de aguas subterráneas. La aproximación es aplicada a un acuífero real en Bélgica que exhibe una complejo heterogeneidad y anisotropía sedimentaria. Una imagen de ensayo se construyó basada en datos de hidrogeológicos y geológicos de campo. La estadística de múltiples puntos es tomada de esta imagen de ensayo para simular la ocurrencia de hidrofacies, mientras que la variabilidad de la permeabilidad de intrafacies está simulada usando métodos geoestadísticos convencionales basados en variogramas. Los ensayos simulados de la conductividad hidráulica son usados como entrada al modelo de flujo y transporte para investigar el efecto de la heterogeneidad sedimentaria de pequeña escala en la migración de la pluma contaminante. Los resultados muestran que la heterogeneidad sedimentaria de pequeña escala tiene un efecto significativo sobre el transporte de contaminantes en el acuífero estudiado. La incertidumbre en la distribución espacial de las facies y la distribución de la conductividad hidráulica de intrafacies da como resultado en una significativa incertidumbre sobre el cálculo de la distribución de la concentración. La comparación con las técnicas standard basadas en variogramas muestra que la geoestadística de múltiples puntos permite una mejor reproducción de cortinas de arcilla de forma irregular y baja permeabilidad que influyen en el transporte de soluto.摘要沉积过程往往会导致水文地质参数在地下空间的复杂的非均质性。基于方差图的随机方法往往不能描述这种复杂地质环境的非均质性。本次工作展示了如何将多点统计地质学应用于实际水文地质问题, 确定复杂的地质非均质性对地下水流和溶质运移的影响。该方法被用于比利时的一个实际的具有复杂的沉积非均质性和各向异性含水层中。根据地质和水文地质实测资料绘制了训练图像。从这个训练图像中得出多点统计数值用于模拟水相分布, 亚相渗透率变化率利用传统的基于方差图的地质统计方法进行模拟。模拟出的水力传导度作为地下水流和溶质运移模型的输入值, 用来研究小范围内沉积造成的非均质性对污染物晕运移的影响。结果显示, 小范围的沉积造成的非均质性对研究目的含水层中的污染物运移有重要影响。空间相分配和亚相水力传导系数分配的不确定性导致计算出的浓度分布的显著不确定性。同标准的基于方差图方法对比, 多点统计地质学能够更好地再现影响溶质运移的不规则形态的低渗透率粘土隔层。ResumoOs processos sedimentológicos resultam frequentemente em heterogeneidades subsuperficiais tridimensionais complexas dos valores dos parâmetros hidrogeológicos. Abordagens estocásticas baseadas na análise variográfica são frequentemente incapazes de descrever a heterogeneidade nesses ambientes geológicos complexos. O presente trabalho evidencia como a geoestatística multiponto pode ser utilizada numa aplicação hidrogeológica realista para determinar o impacte da heterogeneidade geológica complexa no fluxo e transporte hídrico subterrâneo. A abordagem é aplicada a um aquífero real na Bélgica que apresenta uma heterogeneidade e anisotropia sedimentar complexa. É construída uma imagem de treino baseada em dados de campo de natureza geológica e hidrogeológica. As estatísticas multiponto são retiradas desta imagem de treino para simular a ocorrência de hidrofácies, enquanto a variabilidade da permeabilidade intrafácies é simulada utilizando métodos geoestatísticos baseados na análise variográfica convencional. Os resultados da simulação da condutividade hidráulica são utilizados como “input” no modelo de simulação de fluxo e de transporte para investigar o efeito de heterogeneidades sedimentares de pequena escala na migração de plumas de contaminação. Os resultados mostram que as heterogeneidades sedimentares de pequena escala têm um efeito significativo sobre o transporte de contaminantes no aquífero estudado. A incerteza na distribuição espacial das fácies e na distribuição da condutividade hidráulica intrafácies resulta numa incerteza significativa na distribuição das concentrações calculadas. A comparação com técnicas clássicas de análise variográfica mostra que a geoestatística multiponto permite uma melhor reprodução das barreiras argilosas irregulares de baixa permeabilidade que influenciam o transporte em solução.

Estimation of hydraulic conductivity and its uncertainty from grain-size data using GLUE and artificial neural networks

Various approaches exist to relate saturated hydraulic conductivity (Ks) to grain-size data. Most methods use a single grain-size parameter and hence omit the information encompassed by the entire grain-size distribution. This study compares two data-driven modelling methods—multiple linear regression and artificial neural networks—that use the entire grain-size distribution data as input for Ks prediction. Besides the predictive capacity of the methods, the uncertainty associated with the model predictions is also evaluated, since such information is important for stochastic groundwater flow and contaminant transport modelling.Artificial neural networks (ANNs) are combined with a generalised likelihood uncertainty estimation (GLUE) approach to predict Ks from grain-size data. The resulting GLUE-ANN hydraulic conductivity predictions and associated uncertainty estimates are compared with those obtained from the multiple linear regression models by a leave-one-out cross-validation. The GLUE-ANN ensemble prediction proved to be slightly better than multiple linear regression. The prediction uncertainty, however, was reduced by half an order of magnitude on average, and decreased at most by an order of magnitude. This demonstrates that the proposed method outperforms classical data-driven modelling techniques. Moreover, a comparison with methods from the literature demonstrates the importance of site-specific calibration. The data set used for this purpose originates mainly from unconsolidated sandy sediments of the Neogene aquifer, northern Belgium. The proposed predictive models are developed for 173 grain-size Ks-pairs. Finally, an application with the optimised models is presented for a borehole lacking Ks data.

Reservoir characteristics of fault-controlled hydrothermal dolomite bodies: Ramales Platform case study

Abstract Hydrothermal dolomite (HTD) bodies are known as high-quality hydrocarbon reservoirs; however few studies focus on the geometry and distribution of reservoir characteristics. Across the platform-to-basin transition of the Ramales Platform, fault-controlled HTD bodies are present. Three kinds of bodies can be distinguished based on their morphology, that is, elongated HTD corridors, a massive HTD body (Pozalagua body) and an HTD-cemented breccia body. The differences in size and shape of the HTD bodies can be attributed to differences in local structural setting. For the Pozalagua body, an additional sedimentological control is invoked to explain the difference in HTD geometry. A (geo)-statistical investigation of the reservoir characteristics in the Pozalagua body revealed that the HTD types (defined based on their texture) show spatial clustering controlled by the orientation of faults, joints and the platform edge. Porosity and permeability values are distributed in clusters of high and low values; however, they are not significantly different for the three HTD types. Two dolomitization phases (i.e. ferroan and non-ferroan) can be observed in all HTD bodies. In general, the HTDs resulting from the second non-ferroan dolomitization phase have lower porosity values. No difference in permeability is found for the ferroan and non-ferroan dolomites.

Multi-scale three-dimensional distribution of fracture- and igneous intrusion-controlled hydrothermal dolomite from digital outcrop model, Latemar platform, Dolomites, northern Italy

ABSTRACT In recent years, fracture-controlled (hydrothermal) dolomitization in association with igneous activity has gained interest in hydrocarbon exploration. The geometry and distribution of dolomite bodies in this setting are of major importance for these new plays. The Latemar platform presents a spectacularly exposed outcrop analogue for carbonate reservoirs affected by igneous activity and dolomitization. Light detection and ranging (LIDAR) scanning and digital outcrop models (DOMs) of outcrops offer a great opportunity to derive geometrical information. Only a few analysis methods exist to quantitatively assess huge amounts of georeferenced three-dimensional lithology data. This study presents a novel quantitative approach to describe three-dimensional spatial variation of lithology derived from DOMs. This approach is applied to the Latemar platform to determine dolomite body geometry and distribution in relation to crosscutting dikes. A high-resolution photorealistic DOM of the Latemar platform allows description of dolomite occurrences in three dimensions, with high precision at platform scale. This results in a unique lithology dataset of limestone, dolomite, and dike positions. This dataset is analyzed by true three-dimensional variography for the geospatial description of dolomite distribution. In most studies, three-dimensional geostatistics is the combination of two-dimensional horizontal and one-dimensional vertical variation. In this study, the dolomite occurrences are extensive in three dimensions and cannot be reduced to a two-dimensional + one-dimensional case. Therefore, the concept of two-dimensional variogram maps is expanded to a three-dimensional description of lithology variation. Three-dimensional anisotropy detection is used to derive principal directions in the occurrence of dolomite. Two small-scale (

The effect of heterogeneity of diffusion parameters on chloride transport in low-permeability argillites

Understanding flow and transport in low-permeability media is very important in the context of nuclear waste disposal, oil and gas reservoirs and long term evolution of groundwater systems. In low-permeability media, transport by diffusion is often the most important mass transport process. This study investigates the effect of the heterogeneity of diffusion parameters on mass transport in low-permeability media. A geostatistical approach for integrating heterogeneity of diffusion parameters in groundwater flow and transport models is proposed and applied to the Toarcian argillites in France which are studied in the framework of feasibility of storing radioactive waste in deep clayey massifs. Stochastic fields of the diffusion parameters of the Toarcian argillites (France) are generated based on 64 measured values of diffusion coefficient and diffusion accessible porosity and used as input for a 3D local-scale groundwater flow and transport model. The chloride concentrations computed by these heterogeneous models are compared to the measured chloride concentrations and to concentrations calculated with a model in which the Toarcian argillites are subdivided into several homogeneous zones. The heterogeneous simulations result in a slightly better correspondence between measured and calculated values and have the additional advantage that the measured diffusion coefficient values in the Toarcian are perfectly honored in the model. This study shows that small-scale variability of diffusion parameters has a significant effect on solute concentrations and omitting this heterogeneity may be a problem in transport calculations in low-permeability media, depending on the specific setting and objectives of the study.

Reactive transport modeling of redox processes to assess Fe(OH)3 precipitation around aquifer thermal energy storage wells in phreatic aquifers

Well clogging due to iron (hydr)oxide precipitation can negatively influence the performance, or even cause failure, of aquifer thermal energy storage (ATES) wells in aquifers with varying redox conditions. The interactions between physical and chemical processes during ATES operation are, however, not well understood. The reactive transport modeling code PHT3D is used to assess the effects of alternating pumping by ATES systems near the redox boundary on the precipitation of iron hydroxides for two cases, Leuven and Antwerp in the north of Belgium. Results show in both investigated cases that initial mixing plays an important role in the development of Fe(OH)3 precipitation around the wells, with the highest concentration of Fe(OH)3 around the cold well. The initial injection into the warm well causes both the initial mixing and temperature effects to counteract each other, so that the Fe(OH)3 concentration at the cold well is lower and closer to those of the warm well. Since the temperature dependence of the reaction rate of Fe(OH)+, Fe(OH)2 and other reactive species is not taken into account, the impact of the temperature effect on iron (hydr)oxide precipitation should not be viewed quantitatively. However, avoiding the mixing of oxygen/nitrate rich water with iron rich water remains the best strategy to prevent well clogging. Feasibility studies for ATES should therefore assess water quality variations with depth, and use this information to optimize filter screen settings. In this way, the well screen setting can be optimized and the risk of well clogging due to iron (hydr)oxide precipitation is reduced.

Hydrogeological Modeling of Radionuclide Transport in Heterogeneous Low-Permeability Media: A Comparison Between Boom Clay and Ieper Clay

Deep low-permeability clay layers are considered as possible suitable environments for disposal of high-level radioactive waste. In Belgium, the Boom Clay is the reference host formation and the Ieper Clay an alternative host formation for research and safety and feasibility assessment of deep disposal of nuclear waste. In this study, two hydrogeological models are built to calculate the radionuclide fluxes that would migrate from a potential repository through these two clay formations. Transport parameters’ heterogeneity is incorporated in the models using stochastic sequential simulation of hydraulic conductivity, diffusion coefficient and diffusion accessible porosity, using primary information and several types of secondary information, i.e. resistivity, gamma ray and grain size. The calculated radionuclide fluxes in the two clay formations are compared. Results show that in the Ieper Clay larger differences between the fluxes through the lower and the upper clay boundary occur than in the Boom Clay, larger total output radionuclide amounts are calculated than in the Boom Clay, and a larger effect of parameter heterogeneity on the calculated fluxes is observed, compared to the Boom Clay.

Travel time simulation of radionuclides in a 200 m deep heterogeneous clay formation locally disturbed by excavation

In Belgium, the Boom Clay Formation at a depth of 200 m below surface is being evaluated as a potential host formation for the disposal of vitrified nuclear waste. The aim of this study is to model the transport of radionuclides through the clay, taking into account the geological heterogeneity and the excavation induced fractures around the galleries in which the waste will be stored. This is achieved by combining a transport model with geostatistical techniques used to simulate the geological heterogeneity and fractures of the host rock formation. Two different geostatistical methods to calculate the spatially variable hydraulic conductivity of the clay are compared. In the first approach, one dimensional direct sequential co-simulations of hydraulic conductivity are generated, using measurements of hydraulic conductivity (K) and 4 types of secondary variables: resistivity logs, gamma ray logs, grain size measurements and descriptions of the lithology, all measured in one borehole. In the second approach, three dimensional cokriging was performed, using hydraulic conductivity measurements, gamma ray and resistivity logs from the same borehole and a gamma ray log from a second borehole at a distance of approximately 2000 m from the first borehole. For both methods, simulations of the fractures around the excavation are generated based on information about the extent, orientation, spacing and aperture of excavation induced fractures, measured around similar underground galleries. Subsequently, the obtained 3D cokriged and 1D simulated values of hydraulic conductivity are each randomly combined with the simulated fractures and used as input for a transport model that calculates the transport by advection, diffusion, dispersion, adsorption and decay through the clay formation. This results in breakthrough curves of the radionuclide Tc-99 in the aquifers surrounding the Boom Clay that reflect the uncertainty of travel time through the clay. The breakthrough curves serve as a risk management tool in the evaluation of the suitability of the Boom Clay Formation as a host rock for vitrified nuclear waste storage. The results confirm previous calculations and increase confidence and robustness for future safety assessments.

Simulation of radionuclide mass fluxes in a heterogeneous clay formation locally disturbed by excavation

The safe disposal of nuclear waste is an important environmental challenge. Several countries are investigating deep geological disposal as a long-term solution for high-level waste. The Belgian nuclear repository program, conducted by ONDRAF/NIRAS (Belgian agency for radioactive waste and enriched fissile materials), is in the process of characterizing the host rock capacities of the Boom Clay. This is a marine sediment of Tertiary age (Rupelian) (Wouters and Vandenberghe 1994). The research activities are concentrated at SCK●CEN (Belgian Nuclear Research Centre) located on the nuclear zone of Mol/Dessel (province of Antwerp) where an underground experimental facility (HADES-URF) was built in the Boom Clay at 225 m depth. In this area, the Boom Clay has a thickness of about 100 m and is overlain by approximately 180 m of water bearing sand formations. The isolation of waste from the biosphere is obtained by means of a multi-barrier concept, composed of engineered and natural barriers. In this study, the radionuclide migration through the most important natural barrier, the Boom Clay, is investigated. The average hydraulic conductivity value of this formation is very low (

Characterization of spatially variable riverbed hydraulic conductivity using electrical resistivity tomography and induced polarization

The spatial distribution of hydraulic conductivity (K) in riverbeds is essential to understand and model river–groundwater interactions. However, K in riverbeds varies over several orders of magnitude and its spatial distribution is closely linked to complex geological and fluvial processes. Investigating the local distribution and spatial heterogeneity of K is therefore a challenging task. The use of direct current (DC) and time-domain-induced polarization (IP) geoelectrical methods to map qualitatively the spatial distribution of K within riverbeds is described. The approach is demonstrated for a test site situated in a typical lowland river in Belgium. Inverted geophysical parameters (resistivity, chargeability and normalized chargeability) are compared with estimates of K obtained through slug tests. In general, high values of K are observed in the middle of the river and lower values towards the banks, while the opposite is true for chargeability and normalized chargeability. Therefore, there exists an inverse correlation between K and IP geophysical parameters. Furthermore, geostatistical analyses using variograms show that all parameters have ranges of similar magnitudes. The strong correlation between K and chargeability or normalized chargeability can be explained by the fact that all three parameters are mainly controlled by clay and organic matter content.RésuméLa distribution spatiale de la conductivité hydraulique (K) dans les berges est essentielle pour la compréhension et la modélisation des interactions nappe-rivière. Cependant, K varie dans les berges de plusieurs ordres de grandeur et sa distribution spatiale est étroitement liée à des processus géologiques et fluviaux complexes. C’est. pourquoi l’étude de la distribution et de l’hétérogénéité spatiale de K est un défi. L’utilisation des méthodes géophysiques électriques de courant continu (CC) et de polarisation provoquée induite (PI) dans le domaine temporel pour cartographier de manière qualitative la distribution spatiale de K dans les berges est décrite. Cette approche est mise en œuvre sur un site d’essai localisé sur une rivière caractéristique d’une plaine en Belgique. Les paramètres géophysiques déduits (résistivité, chargeabilité et chargeabilité normalisée) sont comparés aux estimations de K obtenues par des tests d’injection. Les valeurs élevées de K sont généralement observées au milieu de la rivière et les plus faibles vers les berges, alors que l’inverse est constaté pour la chargeabilité et la chargeabilité Normalisée. Il existe donc une corrélation inverse entre K et les paramètres géophysiques de PI. De plus, les analyses géostatistiques reposant sur des variogrammes montrent que tous les paramètres ont des variations d’amplitudes comparables. La forte corrélation entre K et la chargeabilité ou la chargeabilité normalisée peut s’expliquer par le fait que les 3 paramètres sont principalement contrôlés par la teneur en argile et en matière organique.ResumenLa distribución espacial de la conductividad hidráulica (K) en lechos de ríos es esencial para comprender y modelar las interacciones río-agua subterránea. Sin embargo, el K en lechos de ríos varía en varios órdenes de magnitud y su distribución espacial está estrechamente relacionada con complejos procesos geológicos y fluviales. La investigación de la distribución local y la heterogeneidad espacial de K es, por lo tanto, una tarea desafiante. Se describe el uso de métodos geoeléctricos de corriente continua (DC) y polarización inducida (IP) en el dominio del tiempo para mapear cualitativamente la distribución espacial de K dentro de los lechos de los ríos. El enfoque se demuestra para un sitio de prueba situado en un río típico de tierras bajas en Bélgica. Los parámetros geofísicos invertidos (resistividad, cargabilidad y cargabilidad normalizada) se comparan con las estimaciones de K obtenidas a través de slug tests. En general, los valores altos de K se observan en el medio del río y los valores más bajos hacia las márgenes, mientras que lo opuesto es cierto para la cargabilidad y cargabilidad normalizada. Por lo tanto, existe una correlación inversa entre los parámetros geofísicos de K e IP. Además, los análisis geoestadísticos que usan variogramas muestran que todos los parámetros tienen rangos de magnitudes similares. La fuerte correlación entre K y la cargabilidad o cargabilidad normalizada se puede explicar por el hecho de que los tres parámetros están controlados principalmente por el contenido de arcilla y materia orgánica.摘要河床水力传导率(K)的空间分布对于了解和模拟河流-地下水相互作用必不可少。然而,河床的K变化达几个数量级,其空间分布与复杂的地质条件和河床演变过程紧密相连。因此,调查K的局部分布和空间异质性是一项具有挑战性的任务。本文论述了采用直流和激发极化地电法定性绘制河床内K 空间分布图。通过位于比利时一个典型低地河流的试验场展示了该方法。反转的地球物理参数(电阻率、荷电率及规范化的荷电率)与通过断塞试验获取的K估算值进行了对比。总的来说,在河流的中部观测到的K值很高,靠近河岸较低,而荷电率及规范化的荷电率正好相反。因此,K和IP地球物理参数之间存在这负相关。此外,采用变异函数进行的地质统计分析显示,所有参数具有类似量级的范围。所有三个参数主要受控于粘土和有机物含量,这一事实能够解释K和荷电率或规范化的荷电率之间很强的相关性。SamenvattingDe ruimtelijke verdeling van hydraulische conductiviteit (K) in rivierbodems is essentieel om interacties tussen rivier en grondwater te begrijpen en modelleren. Maar K varieert over verschillende grootteordes en zijn ruimtelijke verdeling is sterk gerelateerd met complexe geologische en fluviatiele processen. Onderzoek naar de lokale verdeling en ruimtelijke heterogeniteit van K is daarom een uitdagende opdracht. Het gebruik van gelijkstroom en geïnduceerde polarisatie (IP) in het tijddomein als geo-elektrische methoden om de ruimtelijke verdeling van K in rivierbodems kwalitatief in kaart te brengen wordt hier beschreven. De aanpak wordt gedemonstreerd voor een testsite die gesitueerd is in een typische laaglandrivier in België. Geïnverteerde geofysische parameters (resistiviteit, oplaadbaarheid en genormaliseerde oplaadbaarheid) worden vergeleken met schattingen van K, die verkregen werden met behulp van slug tests. Over het algemeen worden hoge waarden van K geobserveerd in het midden van de rivier en lage waarden bevinden zich meer naar de oevers toe, terwijl het omgekeerde geldt voor oplaadbaarheid en genormaliseerde oplaadbaarheid. Er bestaat bijgevolg een inverse correlatie tussen K en geofysische IP parameters. Verder tonen geostatistische analyses met variogrammen dat de ranges van alle parameters gelijkaardige groottes hebben. De sterke correlatie tussen K en oplaadbaarheid of genormaliseerde oplaadbaarheid kan verklaard worden door het feit dat al deze parameters vooral beïnvloed worden door klei en organisch materiaal.ResumoA distribuição espacial da condutividade hidráulica (K) em leitos de rios é essencial para entender e modelar interações entre águas superficiais e subterrâneas. Entretanto, K em leitos de rios varia em varias ordens de grandeza e sua distribuição espacial está intimamente ligada a complexos processos geológicos e fluviais. Investigar a distribuição local e a heterogeneidade espacial da K é, portanto, uma tarefa desafiadora. O uso de métodos geoelétricos de corrente contínua (CC) e polarização induzida por domínio de tempo (PI) para mapear qualitativamente a distribuição espacial da K dentro dos leitos dos rios é descrito. A abordagem é demonstrada para um local de teste situado em um típico rio de planície na Bélgica. Parâmetros geofísicos invertidos (resistividade, carregamento e carregamento normalizado) são comparados com estimativas de K obtidas através de testes de bombeamento (slug test). Em geral, altos valores de K são observados no meio do rio e valores mais baixos em direção às bancadas, enquanto o oposto é verdadeiro para carregamento e carregamento normalizado. Portanto, existe uma correlação inversa entre os parâmetros geofísicos K e IP. Além disso, análises geoestatísticas usando variogramas mostram que todos os parâmetros têm amplitudes similares. A forte correlação entre K e carregamento ou carregamento normalizado pode ser explicada pelo fato de que todos os três parâmetros são controlados principalmente pelo conteúdo de argila e matéria orgânica.