Dissertations / Theses on the topic 'Groundwater fluxes'

Spatio-temporal variability in groundwater discharge and contaminant fluxes along a channelized stream in western Kentucky Surface and groundwater discharges and contaminant fluxes can vary with time and space depending upon the hydrogeological processes and geological setting of the area of interest. This study examined a ~300-m-long, channelized reach of a first-order perennial stream, Little Bayou Creek, in the Coastal Plain of far western Kentucky during the period October 2010–February 2012. Along the study reach, springs discharge groundwater contaminated by the chlorinated organic compound trichloroethene (TCE) and radionuclide technetium-99 (99Tc) released as a result of past activities at the U.S. Department of Energy’s Paducah Gaseous Diffusion Plant. The study addressed variability in groundwater discharge patterns and contaminant concentrations at various timescales (seasonal, annual, and decadal) and the extent to which the discharge sites are spatially persistent. Understanding patterns of groundwater discharge along a stream can be important for assessing the fate and transport of aqueous contaminants. Groundwater discharge was estimated during baseflow conditions using different mass-balance approaches, including velocity-area and dye-dilution gauging. Discharge fluctuated seasonally but typically increased downstream, indicating the entire study reach to be gaining throughout the year. Discharge rates of individual springs also fluctuated seasonally. Tracer test data were utilized to model flow and transient storage along the reach using the USGS software OTIS-P. Cross-sectional area determined from OTIS-P was similar to that measured by velocity-area gauging. Reach area-normalized discharge fluxes were comparable to values determined by Darcy’s law calculations from a pair of monitoring wells at the downstream end of the study reach. Temperature data acquired from probing along grids in winter and summer, from fiber-optic sensing along the reach in autumn, and from data-loggers and manual measurements in springs were used to delineate focused discharge locations. Comparison of temperature-probing results with prior studies indicated that locations of some springs persisted over a decade, whereas other springs emerged and disappeared. Because the stream is located in unlithified sediments, discharge rates of springs appear to fluctuate with soil piping and collapse along joints in fractured clay. Contaminant concentrations in springs decreased downstream along the reach and were lower than observed during September 1999 – May 2001. The continued occurrence of dissolved oxygen and the absence of TCE daughter products in springs suggest that the decrease in TCE concentrations resulted from the installation of upgradient extraction wells, rather than from intrinsic reductive degradation. KEYWORDS: Contaminant fluxes, trichloroethene, technetium-99, baseflow, temperature probing.

There is an extended concern for how to quantify the fluxes of greenhouse gasses (GHG) and how they are related to climate change and land use. Efforts have already been done, mostly regarding carbon (C) compounds, but there is still much to be done especially to understand regulating factors and interactions with the Nitrogen cycle. NitroEurope is a large project for the integrated European research into the N cycle. This study shares its aim, to improve the understanding the physics involved in the fluxes of the reactive N (Nr). More specifically, the patterns of some physical and biological processes related to Nr have been studied for two wetlands, one in the proximity of Edinburgh and the other in the North of Finland.   A common model setup has been used for both of them, since they are both peat soils. The differences applied to achieve appropriate performances give insights of their nature. The presence of snow is a major factor that governs the behavior of the site in Finland. The scaling of existing models for the estimation of heat transfer in the soil of the Scottish site is also critical, such as its groundwater level. The sites represent different climatic conditions, but for CO2 fluxes they showed similar behavior and response to governing meteorological conditions. Using the GLUE method in combination with a process oriented ecosystem model, some further insights have been gained for the regulation and control of greenhouse gas emissions from the two sites.

Les échanges entre les rivières et les nappes d’eau souterraine jouent un rôle essentiel dans le maintien des écosystèmes aquatiques. Or, leur caractérisation demeure difficile du fait de leur forte variabilité dans l’espace et dans le temps. Dans ce contexte, l’objectif de ce travail de thèse est de développer des méthodes actives de mesures distribuées de température pour quantifier la dynamique des interactions nappe/rivière. Après avoir établi une nouvelle approche pour évaluer la résolution spatiale des mesures de température, nous avons validé deux nouvelles méthodes d’interprétation permettant d’estimer de manière distribuée les flux d’eau et la conductivité thermique du milieu poreux. Les travaux, associant modélisations numériques et mesures expérimentales en laboratoire, montrent que les méthodes d’interprétation développées permettent d’estimer avec une excellente précision les écoulements et que la gamme de flux pouvant être investiguée est particulièrement large. Pour tester cette approche prometteuse, des expériences actives ont ensuite été réalisées sur le terrain dans deux environnements différents : d’abord dans un petit cours d’eau d’ordre 1 de tête de bassin versant, puis dans un fleuve s’écoulant le long d’une plaine alluviale. Ces applications ont démontré le fort potentiel des méthodes actives pour quantifier les écoulements à l’interface nappe/rivière et décrire leur variabilité spatiale et temporelle. La comparaison des résultats obtenus sur les deux sites a permis finalement de discuter la faisabilité, les apports mais aussi les limites de la méthode dans différents contextes hydrologiques
Groundwater/surface water interactions play a fundamental role in the functioning of aquatic ecosystems. However, their quantification is challenging because exchange processes vary both in time and space. Here, we propose an active distributed heat transport experiment in order to quantify the spatial and temporal variability of groundwater/surface water interactions. As a first step, we proposed a new approach to evaluate the spatial resolution of temperature measurements. Then, two interpretation methods of active-DTS experiments were developed and fully validated to estimate the distribution of porous media thermal conductivity and the groundwater fluxes in sediments. Based on numerical simulations and sandbox experiments, results demonstrated the potentiality of these methods for quantifying distributed groundwater fluxes with high accuracy. The large range of groundwater fluxes that can be investigated with the method makes specially promising the application of active experiments for many subsurface applications. Secondly, we conducted heat transport experiments within the streambed sediments of two different streams: in a first-order stream, then in a large flow-system located along an alluvial plain. These applications demonstrated the relevance of using active experiments to characterize the spatial complexity of stream exchanges. Finally, the comparison of results obtained for each experimental site allowed discussing the capabilities and limitations of using active-DTS field experiments to characterize groundwater/surface water interactions in different hydrological contexts

Determining sustainable water resource utilization rates is an important problem faced by regulatory agencies all around the world. One of the key parameters in determining accurate water budgeting schemes is the rate of water resource replenishment, or ‘recharge’ in groundwater systems. Fundamental questions regarding groundwater recharge include: What is the source of recharge? What is the spatial distribution of recharge? What is the annual average recharge rate, from potentially disparate sources in disparate areas? Answers to these questions can be gained through combining physical and chemical hydrogeological research tools, including stable isotopic compositions. Land-use intensification, including significant increases in dairying, has placed a priority on developing water resource management practices throughout New Zealand. Here we present the first compilation of delta oxygen-18 and delta hydrogen-2 values from individual precipitation events, local surface waters, depression springs, and groundwaters from the greater-Christchurch area. A variety of analytical methods were used in an effort to evaluate the potential use of stable isotopic compositions as tracers of surface-groundwater interaction in the local hydrologic cycle. The results of this thesis found the isotopic variability of Christchurch precipitation to be highly varied. Back-trajectory analysis of single precipitation events exhibit pathways arriving from three principal sources: the Southern Pacific Ocean, the Tasman Sea, and the Tropical Pacific Ocean. Separately, delta oxygen-18 and delta hydrogen-2 values values from these sources show three distinct local meteoric water lines, which are determined to be largely affected by the environmental conditions present in these areas at the time water vapour formation. Intra-storm variation of extra-tropical cyclones support these findings as significant changes in deuterium excess as moisture sources change with southward movement of the low pressure system. Three line-conditioned tests were subsequently developed to compare the relationship between monthly surface rainfall, surface water, and groundwater samples to the respective moisture origins. Surface rainfall, rainfall infiltration, surface waters, and groundwaters all exhibit the least amount of deviation from the Southern Pacific Ocean local meteoric water line. These observations suggest the principle moisture source to Christchurch to be from west-south westerly flow from the mid-latitudes. However, these similarities do not make partitioning their relative contributions to the groundwater system easy. Previous physical and isotopic investigations have shown the dominant sources of recharge to the Christchurch Groundwater System (CGS) are alpine rivers and local precipitation of which there is statistically significant difference with respect to delta oxygen-18 values. A binary single-isotope mixing model allows for quantification of the relative contributions of alpine river and precipitation derived inputs to local depression springs. The isotopic model indicates that approximately 80% of spring discharge was derived from alpine rivers, in good agreement with recently published physical mass balance model results. Deep groundwater flow paths however show groundwater to flow from the Central Canterbury Plains to the CGS. Potentially including losses from the upper Waimakariri River reaches. If included, this places a net recharge amount to the CGS water budget, which if using losses from only the lower Waimakariri River, there is a net loss. Losses from the upper reaches and subsequent groundwater flow into the CGS are likely as there have been no observed declines in groundwater levels even though there is currently a net loss by only using recharge components within the CGS. Ultimately, recharge from groundwater movement from the Central Canterbury Plains may play significant role; however, a much more sophisticated geochemical model is needed to test these theories and determine contributions. This research demonstrates the utility of stable isotopes as tracers of hydrogeological processes, particularly in shallow groundwater, and their potential contributions to the water resource allocation decision making process.

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences, 1999.
Includes bibliographical references (leaves 85-90).
In this research, the global annual flux of inorganic carbon into groundwater was calculated to be 4.4 GtC/y, with a lower bound of 1.4 GtC/y and an upper bound of 27.5 GtC/y. Starting with 44 soil PCO2 measurements, the dissolved inorganic carbon (DIC) of the groundwater was determined by equilibrium equations for the carbonate system. The calculated DIC was then multiplied by the groundwater recharge to determine the annual carbon flux per area. These PCO2 estimates were assigned to specific bio-temperatures and precipitations according to the Holdridge life-zone classification system, and regressions between PCO2, biotemperature, and precipitation were used to provide estimates for regions of the world that lacked PCO2 measurements. The fluxes were mapped on a generalized Holdridge life-zone map, and the total flux for each life-zone was found by multiplying the calculated flux by the area in each life-zone. While there was a wide range in the error, the calculations in this study strongly suggest that the flux of carbon into groundwater is comparable to many of the major fluxes that have been tabulated for the carbon cycle. The large flux that was calculated in this study was due to the high PCO2 that is common in soils. The elevated PCO2 levels are due to the decomposition of organic matter in soils, and the absorption of oxygen by plant roots. After the groundwater enters into rivers, it is possible that large amounts of CO2 is released from the surface of rives, as the carbon-rich waters re-equilibrate with the low atmospheric PCO2-
by Toby Jonathan Kessler.
S.M.

La qualité des eaux des lacs et le risque d’eutrophisation peuvent être évalués par une étude des composés biogènes. Les sources et les puits de nutriments qui déterminent les processus biogéochimiques peuvent être quantifiés avec un bilan de masse de matière. L’objectif de la thèse était de réaliser ce bilan de masse pour les nutriments dans les deux grands lacs côtiers médocains, Lacanau et Carcans-Hourtin (SW France). Pour cela, j'ai réalisé un suivi de la concentration en nutriments et des paramètres associés des eaux de pluie, des rivières, des canaux, des eaux des lacs et des eaux souterraines au cours de deux cycles hydrologiques en 2014 et 2015. Les processus biogéochimiques à l’interface eau-sédiment et les flux benthiques ont été déterminés à partir de carottes sédimentaires prélevées saisonnièrement et la construction d’une carte sédimentaire des deux lacs. Le bilan hydrologique a pu être réalisé à partir des données de débit et de hauteur d'eau, des mesures géophysiques et des mesures de 222Rn. Nos résultats ont permis de faire un bilan de masse complet de l'azote, du phosphore, de la silice, du fer et de l'alcalinité. Nous avons déterminé les principales sources et les puits de matière et leur évolution au cours de l’année. Les principaux résultats de la thèse sont avant tout la création d’un jeu de données original et riche qui permet pour la première fois d’avoir une vue d’ensemble de la biogéochimique des lacs aquitains. Nous montrons que l’impact des flux souterrains est faible. Les flux benthiques jouent un rôle majeur pour l’azote. L’export de composés biogènes à la sortie des lacs vers le milieu côtier a été quantifié et comparé aux apports par le bassin versant, ce qui a permis d’évaluer la capacité de séquestration des nutriments dans les sédiments. Nous montrons que ces lacs sont pauvres en phosphore, ce qui limite la productivité biologique. Nous avons aussi défini les conditions et les conséquences de la stratification transitoire des eaux des lacs en été. Cet ensemble de données a également permis d'apporter des connaissances supplémentaires sur la dynamique du mercure dans les lacs aquitains. Nous montrons le rôle que jouent les apports en sulfate du bassin versant sur la production de méthylmercure dans les sédiments
To evaluate water quality and the risk of eutrophication of lakes, the dynamics of biogenic compounds must be studied. Sources and sinks of nutrients that define lake biogeochemical processes can be assessed from a mass balance approach and the study of internal reactions. The objective of the thesis was to realize a mass balance for nutrients in two coastal lakes: Lacanau and Carcans-Hourtin (SW France). For this purpose, I conducted a monitoring of rainwater, rivers, canals, lakes and groundwater concentration of nutrients and associate parameters during the two hydrological cycles of 2014 and 2015. Biogeochemical processes at the sediment water interface and benthic fluxes were determined from sediment cores collected at each season, and from the drafting of a new sediment map. The water balance was obtained from water level and discharge measurements, geophysical prospection and 222Rn measurements. Our results allowed us to make a full mass balance of nitrogen, phosphorus, silica, iron and alkalinity. We have identified the main sources and sinks of nutrients and their evolution along the year. The main results of the thesis is that groundwater discharge is not a significant contribution of nutrients; benthic fluxes supply high amount of dissolved nitrogen and most of the nutrient are sequester in the lake sediments. Total export of nutrient at the outlet of lakes has been quantified and compared to inputs from the watershed. We point out that phosphorus limits lake productivity. We also show the dynamics of transient lake stratification in summer and its impact on biogeochemical processes. This set of data has also provided additional insight into the dynamics of mercury in Aquitaine lakes. We show the role of sulphate inputs from the watershed in the production of methylmercury in lake sediments. All these results give for the first time an overall view of Aquitaine lake biogeochemistry

Thesis (Ph. D.)--Civil and Environmental Engineering, Georgia Institute of Technology, 2007.
Koros, William, Committee Member ; Huang, Ching-Hua, Committee Member ; Hughes, Joseph, Committee Member ; Pennell, Kurt, Committee Chair ; Loeffler, Frank, Committee Member.

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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)
Em área contaminada por hidrocarbonetos, situada no município de Paulínia, a migração dos contaminantes e a eficiência do sistema de bombeamento são governadas pela heterogeneidade litológica do aqüífero local, constituído por rochas do Subgrupo Itararé, rochas intrusivas básicas da Formação Serra Geral e por sedimentos cenozóicos correlatos à Formação Rio Claro. Desta forma, o entendimento da heterogeneidade que caracteriza este aqüífero e suas propriedades hidráulicas é essencial para a otimização e o aprimoramento do processo de remediação. Visando delinear o entendimento e a caracterização hidrogeológica local, foi elaborado modelo hidrogeológico conceitual, por meio da integração de dados provenientes de técnicas tradicionais de investigação, tais como métodos geofísicos, monitoramento dos níveis piezométricos de poços de monitoramento, descrições geológicas e análises granulométricas, para entendimento da dinâmica de fluxo local, distribuição litológica do substrato aqüífero e seus valores de condutividade hidráulica. Foram ainda realizadas simulações numéricas de fluxo em regime permanente, utilizando o software Visual Modflow, que emprega o método de diferenças finitas para testar o modelo conceitual concebido. A simulação numérica apresentou excelentes correlações entre os valores de cargas hidráulicas medidas e simuladas e os resultados obtidos permitiram verificar a consistência do modelo conceitual.
In an hydrocarbon contaminated area locate in Paulínia city, lithological heterogeneity of local aquifer controls the migration of contaminant and the efficiency of pump system. The aquifer is composed by sedimentary rocks of Itararé Sub-group, basic intrusive of Serra Geral Formation and cenozoic sediments correlated to Rio Claro Formation. Therefore, understanding heterogeinity that characterize the aquifer and its hydraulic properties is vital to optimization and improvement of remediation process. For hydrogeological characterization of the local aquifer, a conceptual hydrogeological model was elaborated by integrating traditional investigations tools, such as geophysical methods, piezometric level monitoring, and geological descriptions in drillings and granulometric analysis to understanding of local dynamic flow, lithological distributions and hydraulic conductivity. Numerical simulation under steady-state condition using Visual Modflow, which utilizes the finite differences method were performed to test the conceived conceptual model. The measured and calculated hydraulic heads are in excellent agreement, showing the consistency of the conceptual model.

Conselho Nacional de Desenvolvimento CientÃfico e TecnolÃgico
O trabalho desenvolvido mostra uma simulaÃÃo computacional do fluxo hÃdrico subterrÃneo em uma regiÃo do vale do Cariri cearense, que abrange partes das cidades de Barbalha e MissÃo Velha. A modelagem foi realizada com o pacote MODFLOW contido no programa Processing MODFLOW Pro. Foram simulados entÃo, para os estados transiente e estacionÃrio, os cenÃrios no perÃodo seco e chuvoso, e os resultados mostram uma idÃia do comportamento do nÃvel potenciomÃtrico e da direÃÃo do fluxo da regiÃo de estudo. Em um outro momento foi desenvolvida uma interface, em DELPHI 5.0, para o procedimento de calibraÃÃo dos parÃmetros hidrodinÃmicos (condutividade hidrÃulica e transmissividade) denominada de Interface do MÃtodo Iterativo do Gradiente HidrÃulico Alternativo (IMIGHA). Essa interface calibra o modelo a partir dos dados de carga hidrÃulica observada e mostrou ser, pelos exemplos de validaÃÃo, um mÃtodo aplicÃvel e prÃtico. Mas a utilizaÃÃo na Ãrea de estudo simulada, desse procedimento de calibraÃÃo iterativo, mostrou que os resultados satisfatÃrios dependem de uma boa distribuiÃÃo e da quantidade dos dados de carga hidrÃulica na Ãrea de interesse.
The current work presents a computer simulation of groundwater flow in the Cariri Valley, which is located in the State of CearÃ. The cities of Barbalha and MissÃo Velha are located inside this area. In order to perform the computer modeling the software Processing MODFLOW Pro was used. It was used both permanent and time dependent situations. Also both rainy and dry seasons periods we simulated. Among the results, it is show the variation of the groundwater levels and the direction of the flow. As a part of the work, a computer code, using DELPHI 5.0, was developed in order to implement the calibration of hydrogeologic parameters, such as hydraulic conductivity. This code is actually an interface between MODLFOW and the Alternate Hydraulic Gradient Method. This interface uses input date measured groundwater levels and it is on iterative method. Although, in the area of study this method could not reach satisfactory calibration results since accuracy of know groundwater levels and well discharge, as well as topographic contours were poor, the method seem to be valuable.

Orientador: Rodrigo Lilla Manzione
Banca: João Carlos Cury Saad
Banca: Paulo Henrique Ferreira Galvão
Resumo: Os usos de técnicas de modelagem em águas subterrâneas vêm sendo amplamente utilizado para entender a variabilidade e as incertezas associadas às condições hidrodinâmicas dos aquíferos. Os modelos numéricos de fluxo das águas subterrâneas são utilizados para representar a distribuição da carga hidráulica, bem como a velocidade e volume de escoamento da água no aquífero. O Estado de São Paulo possui algumas unidades de conservação de proteção integral, chamadas de Estações Ecológicas. Na região hidrográfica do Médio Paranapanema (UGRHI-17), destaca-se a Estação Ecológica de Santa Barbara (EEcSB), localizada sob uma transição do Sistema Aquífero Bauru (SAB) e o Sistema Aquífero Serra Geral (SASG). A principal atividade econômica na região é a agricultura, onde as águas subterrâneas e superficial são captadas para a irrigação. A demanda excessiva pode ameaçar os recursos hídricos e os ecossistemas da região. Desse modo, foi analisado nesse estudo qual o papel da EEcSB como área de garantia de recarga, utilizando a modelagem do fluxo das águas subterrâneas a partir da plataforma FREEWAT, que utiliza o código MODFLOW de diferenças finitas para simulação numérica. Gerou-se uma camada de espessura variada, representado o SAB. A discretização horizontal foi de 7.789 células ativas, com extensões de 100 m x 100 m. Foram utilizados 23 poços de observação, distribuídos por entre as microbacias da EEcSB, para calibração do modelo. A recarga foi dívida em duas zonas para representar a EEc... (Resumo completo, clicar acesso eletrônico abaixo)
Abstract: The uses of groundwater modeling techniques have been widely applied to understand the variability and uncertainties associated with the hydrodynamic conditions of aquifers. Numerical groundwater models are used to represent the hydraulic head distribution, as well as the velocity and volumetric flow. The São Paulo State has some Conservation Units of integral protection, called Ecological Stations. In the Médio Paranapanema Hydrographic region (UGRHI-17), stands out the Santa Bárbara Ecological Station (EEcSB), located under a transition from the Bauru Aquifer System (BAS) and the Serra Geral Aquifer System (SGAS). The main economic activity in the region is agriculture, where the groundwater and surface water are extracted for irrigation. The excessive demand of water threatens the region's water resources and ecosystems. Thus, in this study, the role of EEcSB as a recharge guarantee area, was analyzed through groundwater flow modeling through the FREEWAT platform, that uses the MODFLOW finite difference code for numerical approximation. One layer of varied thickness, representing the BAS was generated. The horizontal discretization was made of 7,789 active cells, with 100 m x 100 m extension. Twenty three observation wells were used, distributed among EEcSB micro-basins for calibration. The recharge was divided in two zones, to represent the EEcSB and the other land uses in the environment. Recharge values varied around 15% of average rainfall. The two BAS formations (Adam... (Complete abstract click electronic access below)
Mestre

This dissertation develops an analytical-numerical approach to deterministically predict the space-time evolution of concentrations in heterogeneous geologic media conditioned on measurements of hydraulic conductivities (transmissivities) and/or hydraulic heads. Based on the new conditional Eulerian-Lagrangian transport theory by Neuman, we solve the conditional transport problem analytically at early time, and express it in pseudo-Fickian form at late time. The stochastically derived deterministic pseudo-Fickian mean concentration equation involves a conditional, space-time dependent dispersion tensor. The latter not only depends on properties of the medium and the velocity but also on the available information, and can be evaluated numerically along mean "particle" trajectories. The transport equation lends itself to accurate solution by standard Galerkin finite elements on a relatively coarse grid. This approach allows computing without using Monte Carlo simulation and explicitly the following: Concentration variance/covariance (uncertainty), origin of detected contaminant and associated uncertainty, mass flow rate across a "compliance surface", cumulative mass release and travel time probability distribution across this surface, uncertainty associated with the latter, second spatial moment of conditional mean plume about its center of mass, conditional mean second spatial moment of actual plume about its center of mass, conditional co-variance of plume center of mass, and effect of non-Gaussian velocity distribution. This approach can also account for uncertainty in initial mass and/or concentration when predicting the future evolution of a plume, whereas almost all existing stochastic models of solute transport assume the initial state to be known with certainty. We illustrate this approach by considering deterministic and uncertain instantaneous point and nonpoint sources in a two-dimensional domain with a mildly fluctuating, statistically homogeneous, lognormal transmissivity field. We take the unconditional mean velocity to be uniform, but allow conditioning on log transmissivity and hydraulic head data. Conditioning renders the velocity field statistically nonhomogeneous with reduced variances and correlation scales, renders the predicted plume irregular and non-Gaussian, and generally reduces both predictive dispersion and uncertainty.

Resumo: Em área contaminada por hidrocarbonetos, situada no município de Paulínia, a migração dos contaminantes e a eficiência do sistema de bombeamento são governadas pela heterogeneidade litológica do aqüífero local, constituído por rochas do Subgrupo Itararé, rochas intrusivas básicas da Formação Serra Geral e por sedimentos cenozóicos correlatos à Formação Rio Claro. Desta forma, o entendimento da heterogeneidade que caracteriza este aqüífero e suas propriedades hidráulicas é essencial para a otimização e o aprimoramento do processo de remediação. Visando delinear o entendimento e a caracterização hidrogeológica local, foi elaborado modelo hidrogeológico conceitual, por meio da integração de dados provenientes de técnicas tradicionais de investigação, tais como métodos geofísicos, monitoramento dos níveis piezométricos de poços de monitoramento, descrições geológicas e análises granulométricas, para entendimento da dinâmica de fluxo local, distribuição litológica do substrato aqüífero e seus valores de condutividade hidráulica. Foram ainda realizadas simulações numéricas de fluxo em regime permanente, utilizando o software Visual Modflow, que emprega o método de diferenças finitas para testar o modelo conceitual concebido. A simulação numérica apresentou excelentes correlações entre os valores de cargas hidráulicas medidas e simuladas e os resultados obtidos permitiram verificar a consistência do modelo conceitual.
Abstract: In an hydrocarbon contaminated area locate in Paulínia city, lithological heterogeneity of local aquifer controls the migration of contaminant and the efficiency of pump system. The aquifer is composed by sedimentary rocks of Itararé Sub-group, basic intrusive of Serra Geral Formation and cenozoic sediments correlated to Rio Claro Formation. Therefore, understanding heterogeinity that characterize the aquifer and its hydraulic properties is vital to optimization and improvement of remediation process. For hydrogeological characterization of the local aquifer, a conceptual hydrogeological model was elaborated by integrating traditional investigations tools, such as geophysical methods, piezometric level monitoring, and geological descriptions in drillings and granulometric analysis to understanding of local dynamic flow, lithological distributions and hydraulic conductivity. Numerical simulation under steady-state condition using Visual Modflow, which utilizes the finite differences method were performed to test the conceived conceptual model. The measured and calculated hydraulic heads are in excellent agreement, showing the consistency of the conceptual model.
Orientador: Chang Hung Kiang
Banca: Edson Cézar Wedland
Banca: Ewerton de Oliveira
Mestre

Des simulateurs numériques sont couramment utilisés pour la prédiction et l'optimisation de l'exploitation d'aquifères et pour la détermination de paramètres physiques (e.g perméabilité) par calcul inverse. L'équation de Richards, décrit l'écoulement d'un fluide dans un milieu poreux non saturé. C'est une équation aux dérivées partielles non linéaires, dont la résolution numérique en grande dimension 3D est très coûteuse et en particulier pour du calcul inverse.Dans ce travail, une méthode de réduction de modèle (ROM) est proposée par une décomposition orthogonale propre (POD) afin de réduire significativement le temps de calcul, tout maîtrisant la précision. Une stratégie de cette méthode est de remplacer localement dans l'algorithme d'optimisation, le modèle fin par un modèle réduit type POD. La méthode de Petroc-Galerkin POD est d'abord appliquée à l'équation de Richards et testée sur différents cas, puis adaptée en linéarisant les termes non linéaires. Cette adaptation ne fait pas appel à une technique d'interpolation et réduit le temps de calcul d'un facteur [10;100]. Bien qu'elle ajoute de la complexité du ROM, cette méthode évite d'avoir à ajuster les paramètres du noyau, comme c'est le cas dans les méthodes du POD par interpolation. Une exploration des propriétés d'interpolation et d'extrapolation inhérentes aux méthodes intrusives est ensuite faite. Des qualités d'extrapolation intéressantes permettent de développer une méthode d'optimisation nécessitant de petits plans d'expériences (DOE). La méthode d'optimisation recrée localement des modèles précis sur l'espace des paramètres, en utilisant une classification à vecteurs de support non linéaire pour délimiter la zone où le modèle est suffisamment précis, la région de confiance. Les méthodes sont appliquées sur un cas d'école en milieu non saturé régit par l'équation de Richards, ainsi que sur un aquifère situé dans le "Table Mountain Group" près de la ville du Cap en Afrique du Sud
The Richards equation describes the movement of an unsaturated fluid through a porous media, and is characterised as a non-linear partial differential equation. The equation is subject to a number of parameters and is typically computationnaly expensive to solve. To determine the parameters in the Richards equation, inverse modelling studies often need to be undertaken. As a solution to overcome the computational expense incurred in inverse modelling, the use of Proper Orthogonal Decomposition (POD) as a Reduced Order Modelling (ROM) method is proposed in this thesis to speed-up individual simulations. The Petrov-Galerkin POD approach is initially applied to the Richards equation and tested on different case studies. However, due to the non-linear nature of the Richards equation the method does not result in significant speed up times. Subsquently, the Petrov-Galerkin method is adapted by linearising the nonlinear terms in the equation, resulting in speed-up times in the range of [10,100]., The adaptation, notably, does not use any interpolation techniques, favouring an intrusive, but physics-based, approach. While the use of intrusive POD approaches add to the complexity of the ROM, it avoids the problem of finding kernel parameters typically present in interpolative POD approaches. Furthermore, the interpolative and possible extrapolation properties inherent to intrusive PODROM's are explored. The good extrapolation propertie, within predetermined bounds, of intrusive POD's allows for the development of an optimisation approach requiring a very small Design of Experiments (DOE). The optimisation method creates locally accurate models within the parameters space usign Support Vector Classification. The limits of the locally accurate model are called the confidence region. The methods are demonstrated on a hypothetical unsaturated case study requiring the Richards equation, and on true case study in the Table Mountain Group near Cape Town, South Africa

Conselho Nacional de Desenvolvimento CientÃfico e TecnolÃgico
Esta pesquisa simula o fluxo hÃdrico subterrÃneo, numa Ãrea inserida ao sul do estado do CearÃ, englobando as cidades de Juazeiro do Norte, Crato e parte de Barbalha, situadas no vale do Cariri. Para isso foi utilizado o pacote MODFLOW, modelo tridimensional de diferenÃas finitas do fluxo de Ãgua subterrÃnea, contido no programa Processing MODFLOW Pro. Os resultados das simulaÃÃes dos cenÃrios no perÃodo chuvoso e seco disponibilizam dados sobre o comportamento do aqÃÃfero e dÃo uma idÃia da utilizaÃÃo dos recursos hÃdricos disponÃveis na Ãrea. Adicionalmente foi desenvolvido um programa em linguagem FORTRAN (Fortran 90 â Compaq Visual Fortran VersÃo 6.5), que utiliza o mÃtodo do gradiente hidrÃulico alternativo (MIGHA), para fazer a calibraÃÃo do modelo a partir dos dados observados de carga hidrÃulica. Essa tentativa de calibraÃÃo do modelo da Ãrea de estudo nÃo deu resultados satisfatÃrios, mas mostrou pelos exemplos de validaÃÃo que o MIGHA Ã aplicÃvel desde que se tenha dados de cargas hidrÃulicas bem distribuÃdos e confiÃveis e em quantidade representativa da Ãrea.
The main objective of this research is to use a computer code to simulate groundwater flow in an area in the south of the state of Cearà situated between the cities of Crato, Juazeiro do Norte and Barbalha, in the âCaririâ Valley. The computer code used was MODFLOW, a 3-D finite difference groundwater flow model. Two different scenarios we simulated: the rainy and the dry season. Besides, a code using the computer language FORTRAN was developed which proposes an alternate to calibrate the model using hydraulic gradients instead of the usual hydraulic heads as the âobjectiveâ functions. This new way of calibrate did not show satisfactory results for the specific area but once it was applied to simple examples it showed promising results.

Using cross-correlation analysis, we demonstrate that flux measurements at observation locations during hydraulic tomography (HT) surveys carry non-redundant information about heterogeneity that are complementary to head measurements at the same locations. We then hypothesize that a joint interpretation of head and flux data can enhance the resolution of HT estimates. Subsequently, we use numerical experiments to test this hypothesis and investigate the impact of stationary and non-stationary hydraulic conductivity field, and prior information such as correlation lengths, and initial mean models (uniform or distributed means) on HT estimates. We find that flux and head data from HT have already possessed sufficient heterogeneity characteristics of aquifers. While prior information (as uniform mean or layered means, correlation scales) could be useful, its influence on the estimates is limited as more non-redundant data are used in the HT analysis (see Yeh and Liu [2000]). Lastly, some recommendation for conducting HT surveys and analysis are presented.

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Existem vários métodos disponíveis para quantificar a recarga subterrânea e cada método possui suas próprias limitações em termos de aplicabilidade e confiança. A maioria deles requer mais que um parâmetro para estimar a recarga, como por exemplo, coeficientes referentes ao tipo de solo, uso e ocupação da área e o comportamento da evaporação e infiltração. Tendo em vista a indisponibilidade de dados em algumas regiões, o cálculo da recarga por estes métodos se tornaria indisponível e muitas vezes inviável. O objetivo do presente estudo foi estimar a recarga a partir de um método simples, com poucos dados de entrada, e confiável. Assim, o estudo pretendeu estimar a recarga do aquífero Rio Claro, no município de Rio Claro-SP, a partir de um dado obtido através da técnica baseada na classificação de áreas hidrologicamente semelhantes, a técnica da regionalização. A recarga foi estimada pela Vazão de Permanência de 95% (Q95), aplicada para a área de 95,7 Km2 de ocorrência da Formação Rio Claro. Foram utilizados dados de precipitação pluviométrica dos anos de 2002 a 2005. A fim de checar os resultados a recarga foi também calculada a partir da aplicação de dois métodos indianos, cujo parâmetro de entrada era apenas o volume de chuva. A recarga média estimada pelos métodos indianos foi calculada em 315,82 mm/ano e 282,94 mm/ano. O método da Q95 resultou a um valor médio de recarga de 175,4 mm/ano, aproximadamente 12% da precipitação, que em comparação às demais metodologias e às recargas encontradas na mesma área por outros autores, é um volume menor
There are Several methods available to quantify ground recharge and each method has its own limitations in terms of reliability and applicability. Most of them requires more than one parameter to estimate the groudwater recharge, as for example, coefficients for the soil type, use and occupation of the area and the evaporation and infiltration. In view of the unavailability of data in some areas, the calculation of groundwater recharge by these methods would become unavailable and often impractical. The objective of this study was to estimate the recharge from a simple method with few input data, and reliable. So, the study intended to estimate the recharge of the Rio Claro aquifer, in the Rio Claro-SP city, from a simple data obtained through the classification based on similar hydrologic areas, the technique of regionalization. The groudwater recharge was estimated by Flow Permanence of 95% (Q95), applied to the area of 95.7 km2 of occurrence of Rio Claro Formation. The study used data on rainfall for the years 2002 to 2005. To check the results, the recharge was also calculated using the application of two Indians methods, which the only input parameter was the amount of rain. The average recharge estimated by Indian methods was calculated on 315.82 mm / year and 282.94 mm / yr. The method of Q95 resulted in an average recharge of 175.4 mm / year, approximately 12% of the precipitation, which in comparison to other methods and recharges, calculated in the same area by other authors, is smaller

Orientador: Antonio Celso de Oliveira Braga
Banca: Cesar Augusto Moreira
Banca: José Luiz Albuquerque Filho
Resumo: Existem vários métodos disponíveis para quantificar a recarga subterrânea e cada método possui suas próprias limitações em termos de aplicabilidade e confiança. A maioria deles requer mais que um parâmetro para estimar a recarga, como por exemplo, coeficientes referentes ao tipo de solo, uso e ocupação da área e o comportamento da evaporação e infiltração. Tendo em vista a indisponibilidade de dados em algumas regiões, o cálculo da recarga por estes métodos se tornaria indisponível e muitas vezes inviável. O objetivo do presente estudo foi estimar a recarga a partir de um método simples, com poucos dados de entrada, e confiável. Assim, o estudo pretendeu estimar a recarga do aquífero Rio Claro, no município de Rio Claro-SP, a partir de um dado obtido através da técnica baseada na classificação de áreas hidrologicamente semelhantes, a técnica da regionalização. A recarga foi estimada pela Vazão de Permanência de 95% (Q95), aplicada para a área de 95,7 Km2 de ocorrência da Formação Rio Claro. Foram utilizados dados de precipitação pluviométrica dos anos de 2002 a 2005. A fim de checar os resultados a recarga foi também calculada a partir da aplicação de dois métodos indianos, cujo parâmetro de entrada era apenas o volume de chuva. A recarga média estimada pelos métodos indianos foi calculada em 315,82 mm/ano e 282,94 mm/ano. O método da Q95 resultou a um valor médio de recarga de 175,4 mm/ano, aproximadamente 12% da precipitação, que em comparação às demais metodologias e às recargas encontradas na mesma área por outros autores, é um volume menor
Abstract: There are Several methods available to quantify ground recharge and each method has its own limitations in terms of reliability and applicability. Most of them requires more than one parameter to estimate the groudwater recharge, as for example, coefficients for the soil type, use and occupation of the area and the evaporation and infiltration. In view of the unavailability of data in some areas, the calculation of groundwater recharge by these methods would become unavailable and often impractical. The objective of this study was to estimate the recharge from a simple method with few input data, and reliable. So, the study intended to estimate the recharge of the Rio Claro aquifer, in the Rio Claro-SP city, from a simple data obtained through the classification based on similar hydrologic areas, the technique of regionalization. The groudwater recharge was estimated by Flow Permanence of 95% (Q95), applied to the area of 95.7 km2 of occurrence of Rio Claro Formation. The study used data on rainfall for the years 2002 to 2005. To check the results, the recharge was also calculated using the application of two Indians methods, which the only input parameter was the amount of rain. The average recharge estimated by Indian methods was calculated on 315.82 mm / year and 282.94 mm / yr. The method of Q95 resulted in an average recharge of 175.4 mm / year, approximately 12% of the precipitation, which in comparison to other methods and recharges, calculated in the same area by other authors, is smaller
Mestre

The major objective of this study is to investigate simplified risk assessment models for pollutant leaching to and migration across groundwater. Data for this study were gathered through bibliographic research and experts’ advice. Three European countries were selected for this investigation: Italy, United Kingdom and Walloon Region. In the first part, the procedures are compared from a theoretical point of view. The Thesis then identifies the tools used by countries and applies them on a synthetic and real case. A sensitivity analysis is performed as well. The cases have highlighted differences in terms of decision-making and shown which parameters mostly affect results.Basing on the results of this research, it can be concluded that all the countries perform Concentration based risk assessment relying on simplified analytical equations and that the way of assessing risk is quite similar. Major differences could be noticed in the choice of factors and relative adjustments for modelling leaching in the vadose zone and in the way to obtain the remedial objectives. Types of solutions for modelling the transport of contaminant across groundwater differ as well. The synthetic case study brings to light some noticeable aspects. Firstly the difficulty in choosing parameters, particularly for the saturated zone, so as to respect the mass balance between saturated and unsaturated condition. Secondly, the fact that some factors, used by countries to simplify the movement of pollutants (i.e. dilution factor), actually have a great influence on results. Therefore their physical consistency and reliability should be further investigated by comparing results of traditional RA tools with numerical models. Finally, the sensitivity analysis has shown that Mass flux approaches may bring additional contribution to the way the presence of Risk is assessed and that research should evolve in this direction.

The magnitude of contaminant mass flux reduction associated with a specific amount of contaminant mass removed is a key consideration for evaluating the effectiveness of a source-zone remediation effort. Thus, there is great interest in characterizing, estimating and predicting relationships between mass flux reduction and mass removal. Intermediate-scale flow- cell experiments and published data for several field studies were examined to evaluate factors controlling the mass-flux-reduction/mass-removal relationship. Flow-cell experiments evaluated the impact of source-zone architecture and flow-field heterogeneity on mass-flux-reduction/mass-removal behavior. Significant reductions in mass flux occurred for systems wherein immiscible-liquid mass was present at both residual saturation and in high saturation pools. For a system with immiscible liquid present in multiple zones of different permeability, an increase in mass flux was observed for late stages of mass removal. Image analysis confirmed that the late stage increase in mass flux was attributed to changes in relative permeability. Early reductions in mass flux were also observed for systems wherein immiscible-liquid mass was poorly accessible to flowing water. End-point analysis, based on comparing masses and mass fluxes measured before and after a source-zone remediation effort, conducted for 21 field remediation projects ranged from slightly less than to slightly greater than one-to-one. Time-continuous analysis, based on continuous monitoring of mass removal and mass flux, performed for two sites illustrated the dependence of the mass-flux-reduction/mass-removal relationship on source-zone architecture and mass-transfer processes. Minimal mass flux reduction was observed for a system wherein mass removal was relatively efficient. Conversely, a significant degree of mass flux reduction was observed for a site wherein mass removal was inefficient. A simple mass-removal function was used to evaluate the measured data at both the intermediate and field scales. This function was unable to capture the complex behavior observed for some of the systems unless specific measurable system parameters were incorporated into the function. Finally, mathematical models of varying complexity used to simulate immiscible liquid dissolution illustrated the dependence of the calibrated dissolution rate coefficient on implicit and explicit consideration of larger-scale factors influencing immiscible liquid dissolution.

La variabilité spatiale de la température des cours d'eau a été analysée à l'échelle régionale sur le bassin la Maine (22350 km²), où le climat est relativement homogène. La température a été mesurée à 44 stations localisées sur des ordres de Strahler allant de 2 à 7. Les résultats montrent que cette variabilité est liée à la distance à la source et aux flux de nappe. De là, un modèle empirique a été développé. Il peut prédire la température hebdomadaire de l'eau avec une RMSE de 1,35 °C et un biais moyen de -0,13 °C. Le modèle à base physique T-NET a été appliqué sur le bassin versant de la Maine afin de comprendre ses points forts et ses faiblesses et comment les résoudre. L'impact de la végétation rivulaire sur la température, via son influence sur le rayonnement solaire et infrarouge a été caractérisé à la résolution métrique grâce à des données LiDAR sur 270 km du Loir. Les performances de T-NET sont améliorées par rapport aux méthodes plus simples de caractérisation de l'ombrage et l'effet de refroidissement de la végétation sur la température maximale journalière a été quantifié. Enfin, les flux de nappe calculés sur le bassin du Loir par le modèle Eaudyssée à la résolution kilométrique et au pas de temps journalier ont été injectés dans le modèle T-NET. L'impact sur les performances de T-NET et l'influence thermique de ces flux de nappe ont été analysés
The spatial variability of stream temperature was analysed at the regional scale on the climatically homogeneous Maine catchment (22350 km²), thanks to temperature measurements of 44 monitoring stations localised on Strahler orders 2 to 7. This variability was found to be linked to the distance from source and the groundwater fluxes. Based on this finding, an empirical model was developed. It can predict weekly water temperature with a RMSE of 1.35 °C and a mean bias of -0.13 °C. The physically based model T-NET was applied on the Maine catchment in order to understand its strong and weak points and suggest potential methods to solve them. The impact of riparian vegetation on stream temperature, via its influence on solar and longwave downward radiation was characterised at the metric resolution thanks to LiDAR data on 270 km of the Loir River. T-NET's performances are improved compared to simpler shade characterisation methods and the vegetation's cooling effect on maximum daily temperature was quantified. Finally, groundwater fluxes computed on the Loir basin by the Eaudyssée model at the kilometric resolution and the daily time step were injected in T-NET. The impact on T-NET's performances, as well as the thermal influence of these groundwater fluxes were analysed

Groundwater interactions at a regional scale are of great importance to characterize subsurface flow processes. Extensive researches have been conducted previously to determine the main factors controlling the regional implications on groundwater flux circulation. Groundwater circulation occurs due to variation in the groundwater table (hydraulic gradient) across the spatial scale. Previous research highlighted the correlation between groundwater table with both topography variation and the recharge from precipitation. This study aims to highlight the impact of these boundary conditions. Five catchments located across different regions of Sweden with different topographical, hydrological, and meteorological properties considered for this study: Bodalsån, Forsmarksån, Tullstorpsån, Sävaån, and Krycklan. Relevant data were collected and numerical models were set up in steady- state conditions for each of these catchments, using 3D Multiphysics COMSOL. Models were set up for both of the boundary conditions, using 10 m grid resolution.Groundwater flux profiles along the depth of the catchments were obtained as a result, in which significant differences were observed. This was associated predominantly with the difference in the nature of the topography, the slope and soil permeability in these regions. The data thus collected and the models so established have increased the understanding in these regions from a research perspective.
En ökad förståelse för hur grundvatten interagerar med ytvatten är av stor betydelse för att karakterisera underjordiska flödesprocesser. Omfattande undersökningar har tidigare genomförts för att bestämma de viktigaste faktorerna som styr de regionala konsekvenserna för cirkulationen av grundvattenflöde. Grundvattencirkulation uppstår på grund av variationer i grundvattentabellen (hydraulisk gradient) över den rumsliga skalan. Tidigare forskning belyste korrelationen mellan grundvattentabellen med både topografivariation och laddning från nederbörd. Denna studie syftar till att belysa effekterna av dessa gränsförhållanden. Fem avrinningsområden placerade över olika regioner i Sverige med olika topografiska, hydrologiska och meteorologiska egenskaper som beaktas för denna studie: Bodalsån, Forsmarksån, Tullstorpsån, Sävaån och Krycklan. Relevanta data samlades in och numeriska modeller sattes upp under steady-state-förhållanden för vart och ett av dessa avrinningsområden med användning av 3D Multiphysics COMSOL. Modeller konfigurerades för båda gränsförhållandena med 10 m nätupplösning. Grundvattenflödesprofiler längs avrinningsdjupet erhölls som resultat, där signifikanta skillnader observerades. Detta var främst förknippat med skillnaden i topografins natur och lutningen i dessa regioner. De data som samlats in och de så etablerade modellerna har ökat skapat en värdefull grund för vidare hydrologisk forskning i dessa regioner.

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Os usos de técnicas de modelagem em águas subterrâneas vêm sendo amplamente utilizado para entender a variabilidade e as incertezas associadas às condições hidrodinâmicas dos aquíferos. Os modelos numéricos de fluxo das águas subterrâneas são utilizados para representar a distribuição da carga hidráulica, bem como a velocidade e volume de escoamento da água no aquífero. O Estado de São Paulo possui algumas unidades de conservação de proteção integral, chamadas de Estações Ecológicas. Na região hidrográfica do Médio Paranapanema (UGRHI-17), destaca-se a Estação Ecológica de Santa Barbara (EEcSB), localizada sob uma transição do Sistema Aquífero Bauru (SAB) e o Sistema Aquífero Serra Geral (SASG). A principal atividade econômica na região é a agricultura, onde as águas subterrâneas e superficial são captadas para a irrigação. A demanda excessiva pode ameaçar os recursos hídricos e os ecossistemas da região. Desse modo, foi analisado nesse estudo qual o papel da EEcSB como área de garantia de recarga, utilizando a modelagem do fluxo das águas subterrâneas a partir da plataforma FREEWAT, que utiliza o código MODFLOW de diferenças finitas para simulação numérica. Gerou-se uma camada de espessura variada, representado o SAB. A discretização horizontal foi de 7.789 células ativas, com extensões de 100 m x 100 m. Foram utilizados 23 poços de observação, distribuídos por entre as microbacias da EEcSB, para calibração do modelo. A recarga foi dívida em duas zonas para representar a EEcSB ou outros usos da terra no entorno. Os valores variaram entre 15% de recarga da precipitação média. As duas formações do SAB contidas na EEcSB (Adamantina e Marilia) foram representadas por zonas com diferentes condutividades hidráulicas, a primeira com 1,75 m/d e a segunda com 0,9 m/d. A análise de sensibilidade foi realizada automaticamente pelo módulo UCODE_2014 e demonstrou que os parâmetros com maior sensibilidade foram a condutividade hidráulica na zona 1 e a recarga. A calibração teve um erro médio quadrático residual de 0,52 m. O valor total de afluxo simulado pelo modelo em regime permanente é de 66.893,882 m³/d, onde 59.079 m³/d correspondem ao volume escoado pelos drenos, e 7.813 m³/d ao valor de saída pela evapotranspiração. Foram observados três padrões principais de fluxo, com um divisor de águas subterrâneas no centro do domínio simulado. Um padrão de fluxo possui sentido Oeste em direção ao Rio Capivari, apresentando segmentações nas direções de fluxo próximas aos córregos afluentes (Divisa, Santana, Guarantã e Boi). Foram simulados dois cenários, o primeiro com a remoção de 50% da área e o segundo com remoção total da EEcSB. O primeiro cenário apresentou redução de 53,6% no volume da recarga e 47,5% no volume das drenagens, com quedas de até 11m no nível freático. O segundo cenário apresentou uma redução de 61,68% na recarga e de 77,79% na vazão das drenagens com rebaixamentos de até 14m no nível freático.
The uses of groundwater modeling techniques have been widely applied to understand the variability and uncertainties associated with the hydrodynamic conditions of aquifers. Numerical groundwater models are used to represent the hydraulic head distribution, as well as the velocity and volumetric flow. The São Paulo State has some Conservation Units of integral protection, called Ecological Stations. In the Médio Paranapanema Hydrographic region (UGRHI-17), stands out the Santa Bárbara Ecological Station (EEcSB), located under a transition from the Bauru Aquifer System (BAS) and the Serra Geral Aquifer System (SGAS). The main economic activity in the region is agriculture, where the groundwater and surface water are extracted for irrigation. The excessive demand of water threatens the region’s water resources and ecosystems. Thus, in this study, the role of EEcSB as a recharge guarantee area, was analyzed through groundwater flow modeling through the FREEWAT platform, that uses the MODFLOW finite difference code for numerical approximation. One layer of varied thickness, representing the BAS was generated. The horizontal discretization was made of 7,789 active cells, with 100 m x 100 m extension. Twenty three observation wells were used, distributed among EEcSB micro-basins for calibration. The recharge was divided in two zones, to represent the EEcSB and the other land uses in the environment. Recharge values varied around 15% of average rainfall. The two BAS formations (Adamantina and Marillia) at EEcSB were represented by two zones with different hydraulic conductivity, the first with 1.75 m.d-1, and the second with 0.9 m.d-1. The sensitivity analysis was performed automatically by UCODE_2014 module and showed that the parameters with the highest sensitivity were the hydraulic conductivity at zone 1 and the recharge. The calibration had a mean square residual error of 0.52 m. The total value of simulated inflow by the steady state model is 66,893,882 m³.d-1 where outflow was 59,079 m³.d-1 by the leakage into the drains, and 7,813 m³.d-1 by evapotranspiration. Three main flow patterns were observed, with a groundwater divide at the center of the simulated domain. A flow pattern runs westward toward the Capivari Rver, showing segmentations in the flow directions near the tributaries (Divisa, Santana, Guarantã and Boi). Two scenarios were simulated, the first with the removal of 50% of the area and the second one with total removal of the EEcSB. The first scenario presented a reduction of 53.6% in the recharge volume and 47.5% in the drainage volume, with decreases up to 11 m in the water table. The second scenario presented a reduction of 61.685 in recharge and 77.79% n drainage flow with decreases up to 14 m in the water table.

Peatlands are significant soil carbon and freshwater reservoirs at the global scale, and thus play a key role in the global carbon and water cycles. Peatland inception and development are intrinsically related to optimal environmental conditions, including an adequate hydro-morphological setting that promotes the occurrence of waterlogged soils and low topographic gradients. This thesis investigates the hydrology of 0.2 km2 northern peatland complex, located in the region of Schefferville, Québec, Canada, in which a significant area has developed over a relatively steep topographic gradient. The objective of this thesis is to quantify and characterize the spatiotemporal flux of regional groundwater to the peatland local flow system in an attempt to evaluate the relative importance of this flux compared with other water inputs. A three-dimensional groundwater flow model, the finite-difference U.S. Geological Survey MODFLOW code, is used to simulate the peatland and characterize the groundwater flow system. The model is parameterized with data measured from June 17th to September 4th, 2009, including continuous meteorological measurements from an automatic weather station, 14 observation wells, and two 90° V-notch weirs gauging stream discharge. This study establishes that, over the measuring period, the regional groundwater influx accounted for 27% ± 0.4% of the total water inputs, the remainder 73% ± 0.4% consisting of precipitation (54% ± 0.4%), surface water inflow (14% ± 0.4%), and change in storage (5% ± 0.4%). Consequently, it is the main conclusion of this work that regional groundwater inflows were, volumetrically, the second most important source of water to the peatland local flow system.
Les tourbières représentent d'importants réservoirs naturels riches en carbone et en eau douce à l'échelle globale. Ils jouent par conséquent un rôle majeur à la fois dans le cycle du carbone et le cycle hydrologique. L'origine et le développement des tourbières sont liés à l'existence de circonstances environnementales optimales. Il s'agit essentiellement d'un contexte hydro-morphologique adéquat favorisant l'occurrence de sols saturés en eau sur des terrains relativement plats. Ce document présente les résultats d'une étude scientifique conduite dans un complexe tourbier nordique, situé dans la région de Schefferville, Québec, Canada. Ce terrain représente un cas particulier peu observé dans la nature : une large partie de l'accumulation de matière organique a eu lieu sur un gradient topographique prononcé. L'objectif de cette étude est de quantifier et caractériser le flux spatiotemporel du système de circulation de l'eau souterraine régional à la nappe d'aquifère du système tourbier local. Un modèle numérique de circulation de l'eau souterraine est utilisé afin de simuler le système tourbier et caractériser son régime hydraulique. Basé sur le code informatique du modèle MODFLOW, développé par le Service de Géologie des Etats Unis (McDonald and Harbaugh 1988), le modèle tridimensionnel est utilisé afin de simuler la circulation des eaux sou terraine. Le modèle incorpore une série de données météorologiques et hydrométriques en tant que paramètres d'entrée. Mesurées entre le 17 juin et le 4 septembre 2009, ces données proviennent d'une station météo installée pour les besoins de l'étude sur le terrain même, ainsi que 14 puits d'observations et 2 barrages pour mesure le débit. Cette étude établit que, sur l'ensemble de la période d'étude, le flux de l eau souterraine du système régional a représenté 27% des entrées en eau. Les 73% restant se divisent entre 54% pour la précipitation, 14% pour l influx de surface et 5% pour le changement de stockage hydraulique. En conséquence, la conclusion majeure de cette étude est que le flux régional d'eau souterraine est, d'un point de vue volumétrique, le deuxième flux le plus important dans le system tourbier nordique.

The need to consider groundwater and surface water as a single resource has fostered the interest of the scientific community on the interactions between surface water and groundwater. The region below and alongside rivers where surface hydrology and subsurface hydrology concur is the hyporheic zone. This is the region where water exchange determines many biogeochemical and ecological processes of great impact on the functioning of rivers. However, the complex processes taking place in the hyporheic zone require a multidisciplinary approach. The combination of innovative point and distributed techniques originally developed in separated disciplines is of great advantage for the indirect identification of water exchange in the hyporheic zone. Distributed techniques using temperature as a tracer such as fiber-optic distributed temperature sensing can identify the different components of groundwater-surface water interactions based on their spatial and temporal thermal patterns at the sediment-water interface. In particular, groundwater, interflow discharge and local hyporheic exchange flows can be differentiated based on the distinct size, duration and sign of the temperature anomalies. The scale range and resolution of fiber-optic distributed temperature sensing are well complemented by geophysics providing subsurface structures with a similar resolution and scale. Thus, the use of fiber-optic distributed temperature sensing to trace flux patterns supported by the exploration of subsurface structures with geophysics enables spatial and temporal investigation of groundwater-surface water interactions with an unprecedented level of accuracy and resolution. In contrast to the aforementioned methods that can be used for pattern identification at the interface, other methods such as point techniques are required to quantify hyporheic exchange fluxes. In the present PhD thesis, point methods based on hydraulic gradients and thermal profiles are used to quantify hyporheic exchange flows. However, both methods are one-dimensional methods and assume that only vertical flow occurs while the reality is much more complex. The study evaluates the accuracy of the available methods and the factors that impact their reliability. The applied methods allow not only to quantify hyporheic exchange flows but they are also the basis for an interpretation of the sediment layering in the hyporheic zone. For upscaling of the previous results three-dimensional modelling of flow and heat transport in the hyporheic zone combines pattern identification and quantification of fluxes into a single framework. Modelling can evaluate the influence of factors governing groundwater-surface water interactions as well as assess the impact of multiple aspects of model design and calibration of high impact on the reliability of the simulations. But more importantly, this modelling approach enables accurate estimation of water exchange at any location of the domain with unparalleled resolution. Despite the challenges in 3D modelling of the hyporheic zone and in the integration of point and distributed data in models, the benefits should encourage the hyporheic community to adopt an integrative approach comprising from the measurement to the upscaling of hyporheic processes.

Les apports d’eaux souterraines (Submarine Groundwater Discharge : SGD) peuvent constituer des apports considérables d'eau et de nutriments ou de contaminants en zone côtière. Le suivi des radio-éléments (radon, radium) dans ces zones permet de tracer les apports de SGD et leurs bilans de masse permettent de quantifier leurs flux. Cette méthode est utilisée depuis des années, mais les termes des bilans aux interfaces restent difficiles à appréhender. L'objectif de cette thèse est d'apporter des précisions sur ces termes afin de permettre une meilleure quantification des flux de SGD. Pour l'interface air-eau, les flux de dégazage du radon vers l'atmosphère ont été estimés pour différentes conditions de vent sur l’étang de Berre. Un dégazage permanent, même sans vent, a été mis en évidence. Pour l'interface sédiment-eau, nous décrivons une méthode de calcul et d’évaluation du flux diffusif du radon et proposons une nouvelle approche pour estimer celui du radium. Dans la lagune de Mar Menor, les flux de SGD estimés sont 5 à 200 fois plus élevés que les apports d'eau par les rivières et sont majoritairement causés par de la recirculation d’eau à travers les sédiments. Pour la première fois les suivis de radio-éléments ont été combinés à un modèle hydrodynamique, ce qui a permis de localiser précisément les SGD. L'étude du système karstique de la source de la calanque de Port-Miou a mis en évidence un système bicouche de la colonne d'eau. La combinaison des bilans en radio-éléments, d'eau et de sel nous a permis d'estimer un débit de la source très proche de celui mesuré par différence de pression, attestant ainsi de la fiabilité de cette méthode pour les systèmes karstiques
Submarine Groundwater Discharges (SGD) may represent important inputs of water, nutrients as well as contaminants to the coastal zone. Monitoring radionuclides (radon, radium) in those areas allows to trace SGD inputs while their fluxes may be quantified through their mass balances. This method has been used for many years, even though the terms from the mass balance at these interfaces remain difficult to manage. The objective of this thesis is to develop methods to better describe and evaluate these terms, in order to get a better quantification of SGD fluxes. For the air-water interface, the radon atmospheric fluxes have been estimated for different wind conditions on the Berre lagoon. A permanent flux, even without wind, has been highlighted. For the sediment-water interface, new methods are proposed here in order to calculate and evaluate the radon diffusive flux, as well as a new approach for estimating the radium diffusive flux. In the Mar Menor, the estimated SGD fluxes are 5 to 200 times higher than water river inputs and are predominantly caused by lagoon water recirculation through sediments forced by tidal pumping. For the first time, the monitoring of radionuclides in this lagoon was combined to a hydrodynamic model, allowing to locate precisely the SGD inputs. The study of the karstic spring of the Port-Miou calanque shows a two-layer system in the water column. The combination of radionuclides, water and salt mass balances leads to calculate a spring flux similar to the one measured by pressure gradient, which confirms the reliability of this method for karstic systems

Variabilities of hydraulic and solute transport properties of soil are examined at three scales: pore-scale, sample volume-scale, and field-scale. Undisturbed soil cores were taken at 19 subsites spaced logarithmically along a 150 m line transect in a Groseclose mapping unit near Blacksburg; Virginia. Three core sizes were taken at each subsite at the soil surface and 0.5 m depth. 'Small' cores were-40x54 mm; 'medium' cores were 60X100 mm; and 'large' cores were 100x150 mm. Macropore effects on solute transport were evaluated using monocontinuum and bicontinuum models. Bicontinuum-predicted solute breakthrough curves (BTC) closely agreed with observed BTC data with mean errors of reduced concentrations
Master of Science

Les études isotopiques couplées avec des informations géothermiques peuvent constituer des outils pertinents pour l’exploration des eaux souterraines en tant que ressources en eau potable ou géothermiques. Ce travail combine les deux approches, isotopes de l’environnement et radioactifs associés à des données de température sur des aquifères profonds, dans l’objectif d’enrichir et d’améliorer la connaissance des mécanismes de recharge (Bassin d’Aquitaine, France) ainsi que des mécanismes de recharge et du potentiel géothermique (Bassin Crétacé de Bohème, République Tchèque).Les isotopes stables (18O, 2H, 13C) utilisés conjointement avec des radioisotopes (14C, 3H) sont utilisés pour estimer l’époque de la recharge ainsi que les conditions climatiques qui prévalaient lors de l’infiltration depuis la fin de Pléistocène jusqu’à nos jours. Définir le type de recharge et les conditions d’écoulement est nécessaire pour parvenir à modéliser de façon satisfaisante et fiable les grands systèmes aquifères profonds. Trois types de recharge ont été définis en Europe - (i) continue, (ii) interrompue lors du dernier maximum glaciaire (LGM) – un troisième type (iii) correspond à des situations particulières de recharge.Les conditions géographiques et climatiques très différentes rencontrées en France et en République Tchèque ont engendrées une importante hétérogénéité des conditions et processus de recharge. Le sud de la France, avec un climat relativement doux depuis les derniers 40 ka BP, n’a pas enregistré d’interruption de la recharge. Le temps de séjour des eaux souterraines en Bohème est estimé à environ 11 ka BP au maximum. Cependant, l’appauvrissement des teneurs en isotopes stables enregistré suggère une recharge liée à la fonte de la calotte glaciaire Nord Européenne après le dernier maximum glaciaire (LGM), autour de 18-20 ka BP. Des investigations sur les isotopes du carbone minéral dissous des eaux souterraines du bassin de Bohème ont montrées d’importantes interactions avec différentes sources de carbone qui ont été identifiées.Pour le site d’étude tchèque, les informations apportées par la géochimie ont été complétées par des données géothermiques afin d’améliorer la connaissance des flux et de la dynamique des eaux souterraines. Plus d’une centaine d’enregistrements diagraphiques de température ont été utilisés pour estimer le gradient géothermique. Plusieurs phénomènes viennent perturber le gradient géothermique de la région. Les flux d’eau souterraine verticaux et les variations lithologiques et topographiques sont à l’origine d’une distribution complexe du flux de chaleur, étant majoritairement conditionné par les écoulements souterraines. Les discontinuités peu profondes et les nombreux pointements volcaniques exercent aussi une influence importante sur l’écoulement souterrain et donc aussi sur le potentiel géothermique du réservoir. Les investigations sur la géothermie ont ainsi fourni des informations fondamentales sur le potentiel géothermique mais aussi sur les conditions d’écoulement des eaux souterraines. La prise en compte de ces informations s’avère nécessaire afin de proposer des modèles mathématiques d’écoulement réalistes
Isotopic investigations combined with geothermal applications represent powerful tools for the exploration of groundwater potential as a drinking or geothermal resource. This Ph.D. thesis combines both approaches, environmental and radioactive isotopes together with temperature data in deep aquifers, in order to enrich and update the knowledge concerning the aquifer recharge processes in the Aquitaine Basin (France) and the aquifer recharge processes and geothermal potential in the Bohemian Cretaceous Basin (Czech Republic).Stable isotopes (18O, 2H, 13C) combined with radioisotope data (14C, 3H) are used to estimate the recharge timing and climatic conditions prevailing during the infiltration from the Late Pleistocene up to modern time. The character of groundwater recharge and regime are necessary to generate relevant source data for the accurate modelling of complex groundwater systems. Three groups of groundwater recharge types can be distinguished throughout Europe – (i) continuous recharge and (ii) interrupted recharge during Last Glacial Maximum and (iii) a group corresponding to particular recharge conditions.The contrasted geographic and climate conditions at both study sites in France and Czech Republic have entailed a great heterogeneity of the recharge conditions and processes. Southern France, with generally mild climatic conditions during the last 40 ka BP, did not experienced considerable hiatus in groundwater recharge. The residence time of groundwater in the Bohemian aquifers is estimated about 11 ka BP at the maximum but the depletion in the stable isotopes suggests that this groundwater originates in the melting of the north European ice sheets after the Last Glacial Maximum period, i.e. 18-20 ka BP. Further investigations on both stable and radioactive carbon isotopes indicated numerous groundwater interactions within the reservoir that were used to delineate the carbon origin within the Bohemian aquifers.Information on groundwater geochemistry was supplemented in the Czech case study by geothermal data in order to improve our knowledge of groundwater flow and dynamics. More than a hundred of temperature records from well-logging measurements were used to assess the geothermal gradient in the Bohemian Cretaceous Basin which is the most promising heat accumulation within the country. Many phenomena can affect the thermal field in the region. Vertical groundwater flow and variations in the lithology and the topography lead to a complicated areal distribution of the geothermal gradient and the heat flux which is dominantly controlled by groundwater. Shallow tectonic structures and numerous volcanic rocks exercise an influence on groundwater flow and therefore exert a secondary effect on the thermal field. The geothermal investigation provided useful information on the geothermal resources within the region but also represents an important tool for understanding groundwater flow, and for constructing realistic hydrogeological models in such a complex geological, tectonic and geothermal context

The Waiwhero wetland (16 ha) is one of the largest wetlands in the Rosedale Hills, 35 km north-west of Nelson, New Zealand. It has an extensive cover of Salix fragilis L. (crack willow) and has been hypothesised to be a source of groundwater recharge for the Moutere aquifers, an important local groundwater system. However the wetland could also be a groundwater discharge zone, because of the geological boundary that it straddles. The overall aim of this study was to determine the direction of groundwater flux of the wetland by measuring the water balance, with particular emphasis on the transpiration rates from the crack willow trees. The average daily transpiration (measurement was for 230 days) of crack willows in the wetland (6.4 mm/day) was close to twice the potential evapotranspiration (PET) for grassland (3.9 mm/day). The highest measured willow transpiration rate was 12.4 mm/day and the lowest was 0.8 mm/day. High transpiration from crack willows was due to the horizontal energy fluxes (advective energy), tree physiological characters and high soil water content. The study established that the wetland is a groundwater discharge zone with, on average for the two summer periods (2008 and 2009), the net groundwater discharge being 4.8 mm/day. The daily water balance results between two major rainfall events showed that the initial discharge source was from the surrounding hills and later stabilized at around 6 to 14 mm/day. It was believed to be a contribution from the shallow and deep aquifers or a combination of local region inflow and aquifers. The water balance showed that the main loss of water through the hydrological system of the wetland during summer was from the high transpiration of willows (7.7 mm/day). The extent of water savings estimated for the 16 ha wetland through a hypothetical situation of willow removal, and the assumption that it is filled with open water without any canopy cover, was 688 m3/day. However this water savings rate if applied to a large area of crack willow stands would be quite high. On similar lines it is important to understand the transpiration rates of other wetland tree species in New Zealand. This information would help in preparing regional council plans for the introduction of tree species in the wetland for better management of the water resources and sustainable ecosystem management.

The Red River Delta in Vietnam is one of the regions whose quaternary aquifers are polluted by arsenic. Chronic toxification by arsenic can cause severe illnesses such as cancer, skin lesions, developmental defects, cardiovascular and neurological diseas-es, and diabetes. In this study, a food processing craft village in the Red River Delta was investigated regarding the potential risk faced by the population due to arsenic. The potential sources of arsenic are the groundwater, the crops grown in the sur-roundings, and animal products from local husbandry. However, the occurrence of arsenic in nature is variable, and its bioavailability and toxicity depend very much on its specification: trivalent compounds are more toxic and often more mobile than pen-tavalent compounds, while inorganic species are generally more toxic than organic ones. Local conditions, such as the redox potential, strongly influence its specification and thus potential bioavailability. The introduction to this work elucidates the key factors which potentially cause human exposure to arsenic: the geological setting of the study area, land and water use pat-terns, and the current state of research regarding the mobilization, bioavailability and plant uptake of arsenic. Although the study area is located in a region where the groundwater is known to be moderately contaminated by arsenic, the level of arsenic in the groundwater in the village had not previously been determined. In this study, water use in the village was examined by a survey among the farmers and by water analyses, which are present-ed in the following chapters. Four main water sources (rain, river, tube well and a pub-lic municipal waterworks) are used for the different daily activities; the highest risk to human health was found to be the bore well water, which is pumped from the shallow Holocene aquifer. The water from the bore wells is commonly used for cleaning and washing as well as to feed the animals and for food processing. Products like noodles and rice wine were examined as well as local pork and poultry. Vegetables from the gardens and rice plants from the surrounding paddy fields were sampled and ana-lyzed. All plants were found to have accumulated arsenic, leafy vegetables showing the highest arsenic concentrations. The results are discussed and compared, and conclusions are drawn in the last part. The reducing conditions in the paddy fields are likely to have a strong influence on arsenic uptake in rice plants and on transport to the aquifer. The installation of a wastewater treatment plant under the research project INHAND, which was funded by the BMBF German Ministry of Education and Research, led to lower arsenic concen-trations in the groundwater. Soaring industrialization, the growing population, and the consumers’ changing behav-ior will widely affect land and water use and hence the potential mobilization of arse-nic. In order to mitigate further human exposure to arsenic, wastewater needs to be treated and the reducing conditions in the rice fields need to be decreased by means of enhanced cultivation methods.

The Red River Delta in Vietnam is one of the regions whose quaternary aquifers are polluted by arsenic. Chronic toxification by arsenic can cause severe illnesses such as cancer, skin lesions, developmental defects, cardiovascular and neurological diseas-es, and diabetes. In this study, a food processing craft village in the Red River Delta was investigated regarding the potential risk faced by the population due to arsenic. The potential sources of arsenic are the groundwater, the crops grown in the sur-roundings, and animal products from local husbandry. However, the occurrence of arsenic in nature is variable, and its bioavailability and toxicity depend very much on its specification: trivalent compounds are more toxic and often more mobile than pen-tavalent compounds, while inorganic species are generally more toxic than organic ones. Local conditions, such as the redox potential, strongly influence its specification and thus potential bioavailability. The introduction to this work elucidates the key factors which potentially cause human exposure to arsenic: the geological setting of the study area, land and water use pat-terns, and the current state of research regarding the mobilization, bioavailability and plant uptake of arsenic. Although the study area is located in a region where the groundwater is known to be moderately contaminated by arsenic, the level of arsenic in the groundwater in the village had not previously been determined. In this study, water use in the village was examined by a survey among the farmers and by water analyses, which are present-ed in the following chapters. Four main water sources (rain, river, tube well and a pub-lic municipal waterworks) are used for the different daily activities; the highest risk to human health was found to be the bore well water, which is pumped from the shallow Holocene aquifer. The water from the bore wells is commonly used for cleaning and washing as well as to feed the animals and for food processing. Products like noodles and rice wine were examined as well as local pork and poultry. Vegetables from the gardens and rice plants from the surrounding paddy fields were sampled and ana-lyzed. All plants were found to have accumulated arsenic, leafy vegetables showing the highest arsenic concentrations. The results are discussed and compared, and conclusions are drawn in the last part. The reducing conditions in the paddy fields are likely to have a strong influence on arsenic uptake in rice plants and on transport to the aquifer. The installation of a wastewater treatment plant under the research project INHAND, which was funded by the BMBF German Ministry of Education and Research, led to lower arsenic concen-trations in the groundwater. Soaring industrialization, the growing population, and the consumers’ changing behav-ior will widely affect land and water use and hence the potential mobilization of arse-nic. In order to mitigate further human exposure to arsenic, wastewater needs to be treated and the reducing conditions in the rice fields need to be decreased by means of enhanced cultivation methods.:Abstract III Zusammenfassung V Acknowledgements VII Contents IX List of abbreviations XIII List of tables XVII 1 Scope of this work 1 2 Introduction 2 2.1 Geographical and geological setting of the study area 2 2.2 Hydrological situation 5 2.2.1 Surface water 5 2.2.2 Impact of human activities on surface water quality and distribution 6 2.2.3 Hydrogeology 7 2.3 Arsenic occurrence 7 2.3.1 Arsenic toxicity 8 2.3.2 Risk potential of arsenic in diet 10 2.4 Arsenic contamination in the groundwater resources of the Red River Delta 11 2.4.1 Occurrence and origin of arsenic in the Red River Delta 12 2.4.2 Mobilization processes 13 2.4.3 As mobilization in paddy fields 15 2.5 Arsenic occurrence in daily rural activities 16 2.5.1 Arsenic in soil 17 2.5.2 Arsenic in drinking water 19 2.5.3 Phytoaccumulation: Current state of research 20 2.5.4 Bioavailablity 22 2.5.5 Arsenic uptake in rice plants 23 2.5.6 Arsenic in meat and animal products 26 2.5.7 Arsenic uptake in golden apple snails 27 2.5.8 Processing: Wine and noodles 28 2.5.9 Arsenic concentrations in wastewater, activated sludge and digestate 29 2.6 Iron and manganese in the nutrient chain 30 2.7 Land and water use in the Red River Delta 31 2.7.1 Historical and political aspects of rural development in Vietnam 33 2.7.2 Craft villages in the Red River Delta 34 3 Materials and methods 36 3.1 Soil sample analyses 36 3.2 Well sampling 37 3.3 Wastewater and sludge analyses 37 3.4 Food analyses 38 3.5 Site visit and field observations 39 3.6 Questionnaire 39 4 Results 40 4.1 Soil samples 40 4.1.1 Total arsenic and total heavy metal concentrations 40 4.1.2 Sequential fractionation procedure 41 4.2 Arsenic in the water cycle in Dai Lam 43 4.2.1 Groundwater analyses 43 4.2.2 Water use in Dai Lam 47 4.2.3 Wastewater in Dai Lam 50 4.3 Arsenic in sewage sludge 51 4.4 Arsenic in manure samples 52 4.5 Arsenic in food samples 52 4.5.1 Rice 52 4.5.2 Arsenic in leaf vegetables 53 4.5.3 Arsenic in poultry products 56 4.5.4 Arsenic in pork samples 57 4.5.5 Arsenic in snails 57 4.6 Economic and demographic development potential 58 5 Discussion 61 5.1 Soil samples 61 5.2 Groundwater samples 62 5.2.1 High arsenic concentrations 62 5.2.2 Strong temporal and spatial variation 63 5.2.3 Weak correlation between measured parameters 69 5.3 Wastewater and sewage sludge 70 5.4 Pig manure 71 5.5 Daily exposure to As from dietary intake 71 5.6 Effects of land and water use on water quality and public health 76 5.7 Against the background of the transition economy 77 6 Conclusion 80 7 Perspectives (further work) 85 8 References 86 9 Annex 110

Das Ziel der vorliegenden Arbeit ist die ausführliche Analyse und Beschreibung langfristiger abiotischer Standortbedingungen von Fluss und Grundwasser für das in einem Hartholzauenwald gelegene Untersuchungsgebiet im Naturschutzgebiet Saalberghau an der Mittleren Elbe bei Dessau. Hierzu erfolgt zunächst die Entwicklung eines allgemeinen Konzeptes, dass die Modellierung des Fluss- und des Grundwasserregimes sowie die statistische Auswertung dieser miteinander verbundenen Regime umfasst. Es wird davon ausgegangen, dass nur eine Synthese dieser Einzelbausteine die Grundlage für eine zusammenhängende Analyse und Beschreibung der komplexen auentypischen Dynamik dieser beiden Regime anhand objektivierbarer statistischer Parameter bilden kann. Darüberhinaus stellt die Zielsetzung auf langfristige Aussagen eine unentbehrliche Voraussetzung dar, um das Zeitspektrum der hier zu betrachtenden Altbäume typischer Hartholzauenbaumarten adäquat berücksichtigen zu können
The present dissertation aims at a detailed analysis and description of the long-term abiotic site conditions (river flow and groundwater) for the floodplain area under investigation, namely a hardwood forest in the nature reserve "Saalberghau" on the Middle Elbe close to the town Dessau. For this purpose, firstly a general concept which covers the modelling of the surface water and groundwater regime as well as a statistical interpretation of these two interconnected regimes is developed. It is assumed that only a synthesis of those separate modules can form a sufficient basis for a cohering analysis and description of the complex dynamics of these two regimes in floodplain forests by means of objective statistic parameters. Furthermore, only longterm statements can take into account the age spectrum of the hardwood stand

Hydrothermal systems change in response to volcanic activity, and in turn may be sensitive indicators of volcanic activity. Fumaroles are a surface manifestation of this interaction. We use time series of soil temperature data and numerical models of the hydrothermal system to investigate volcanic, hydrologic and geologic controls on this diffuse degassing. Soil temperatures were measured in a low-temperature fumarole field located 3.5 km from the summit of Masaya volcano, Nicaragua. They respond rapidly, on a time scale of minutes, to changes in volcanic activity also manifested at the summit vent. The soil temperature response is repetitive and complex, and is characterized by a broad frequency signal allowing it to be distinguished from meteorologic trends. Geophysical data reveal subsurface faults that affect the transport of fumarole gases. Numerical modeling shows that these relatively impermeable faults enhance flow through the footwall. On a larger scale, modeling suggests that uniform injection of fluid at depth causes groundwater convection in a permeable 3-4 km radial fracture zone transecting the entire flank of the volcano. This focuses heat and fluid flux and can explain the three distinct fumarole zones located along the fracture. We hypothesize that the rapid response of fumarole temperature to volcanic activity is due to increased flow of gas through the vadose zone, possibly caused by changes in the subsurface pressure distribution. Numerical models show that an abrupt injection of hot gas, at approximately 100 times background rates, can cause the rapid increase in temperature observed at the fumaroles during volcanic activity. A decrease in hot fluid injection rate can explain the gradual decrease in temperature afterwards. Mixing with surrounding vadose-zone fluids can result in the consistent and abrupt decreases in temperature to background level following hot gas injection. Fumaroles result from complex interaction of the volcanic-hydrologic-geologic systems, and can therefore provide insight into these systems. Increases in fumarole temperature correspond to increased gas flux related to changes in volcanic activity, suggesting that monitoring of distal fumaroles has potential as a volcano monitoring tool, and that fumarole temperatures can provide insight into the response of shallow gas systems to volcanic activity.

La caracterisation de l'agencement spatial des proprietes hydrauliques est essentielle pour predire les ecoulements et le transport des solutes dans les milieux heterogenes. Les methodes de tomographie hydraulique, principalement developpees pour estimer les proprietes des milieux poreux, n'ont qu'une faible r'esolution spatiale qui ne reflete pas la vraie heterogeneite des distributions de fractures des milieux fractures. Le principal objectif de cette these est de developper une nouvelle methode d'inversion specifique pour imager les proprietés hydrauliques et de transport des milieux fractures a l'echelle du site. Pour atteindre ces objectifs, des experiences in situ ainsi qu'une nouvelle approche de modelisation inverse sont proposees, notamment en utilisant la temperature comme marqueur des ecoulements. Nous proposons tout d'abord la tomographie d'ecoulement bas'ee sur des tests s'equentiels de debimetrie entre puits, comme une nouvelle approche pour caracteriser la connectivit'e des fractures ainsi que leur transmissivite. A partir de simulations numeriques reproduisant des cas d'etudes synth'etiques, nous montrons que l'approche par tomographie r'eduit significativement l'incertitude sur les parametres estimes, et fournit une caracterisation detaillee du reseau de fracture sans requerir a l'utilisation d'obturateurs hydrauliques. Nous montrons ensuite comment les mesures de temperature peuvent etre utilisees pour quantifier les ecoulements dans les milieux fractur'es. Le grand int'erˆet d'utiliser la temperature est d'obtenir facilement et de facon continue en puits des profils de temp'erature. En utilisant un mod'ele numerique d'ecoulement et de transfert de chaleur a l'echelle du puits, une methode d'inversion pour estimer les vitesses d'ecoulement dans le puits 'a partir des donnes de temperature est proposee. Nous couplons ensuite les deux approches presentees precedemment dans une nouvelle approche experimentale consistant en des enregistrements sequentiels de temperature dans un puits dans des conditions de pompage entre puits. L'application de cette approche de tomographie en temperature sur le site de Stanger Brune montre des resultats encourageants pour l'identification du reseau global de connectivite et des zones d'ecoulement principales. Enfin, nous discutons de l'interet d'utiliser la chaleur comme traceur par rapport 'a l'utilisation de traceurs classiques. Nous montrons que realiser des tests de tracage thermiques en milieu fracture fournit des contraintes supplementaires importantes sur les propri'et'es de transport du milieu.

L’estudi de la concentració i la distribució de metalls i metal·loides en ambients costaners ha guanyat rellevància durant els darrers quaranta anys, principalment a conseqüència de la creixent preocupació per llurs efectes nocius sobre els ecosistemes i la salut pública. Els cicles dels metalls i metal·loides, amb una gran quantitat de variables físiques, químiques, biològiques i també antropogèniques que hi influeixen, són extremadament complexos, la qual cosa en dificulta la comprensió. Per aquest motiu, la millora de les metodologies i l’aplicació de noves tècniques d’estudi són fonamentals per poder aprofundir en el coneixement dels processos associats a la contaminació i la pol·lució de l’oceà per metalls i metal·loides. En aquest context, aquesta Tesi representa una contribució al desenvolupament i a la integració de les metodologies disponibles per a l’estudi dels fluxos de metalls i metal·loides d’origen antropogènic cap al medi marí. Per atènyer aquest objectiu, la Tesi s’ha centrat en l’estudi de dues vies d’entrada de metalls i metal·loides cap a la mar costanera: les descàrregues d’aigua subterrània (DAS) i l’abocament directe de residus en dues àrees de la costa mediterrània, la costa central de Catalunya i la badia de Portmán, a Múrcia. En primer terme, s’han abordat les metodologies de quantificació de les DAS mitjançant isòtops de Ra i 222Rn. L’anàlisi i monitoratge dels isòtops de Ra a l’aqüífer al·luvial de la riera d’Argentona al llarg de dos anys ha demostrat que la variabilitat observada en llurs concentracions, de més d’un ordre de magnitud, està governada pel desplaçament de la posició de la interfase salina durant períodes de precipitacions abundants. La variabilitat enregistrada en les concentracions dels isòtops dificulta la determinació d’un valor representatiu de Ra a l’aqüífer, la qual cosa és un requeriment necessari per quantificar els fluxos de les DAS. Puix que els fluxos de metalls i metal·loides derivats de las DAS s’incrementen significativament durant els episodis de precipitacions, l’elevada dinàmica dels aqüífers costaners en règims micromareals fa necessari un millor coneixement dels processos hidrogeològics locals o regionals per poder reduir les incerteses associades a la quantificació dels fluxos de metalls i metal·loides als sistemes costaners. En segon terme, la Tesi situa el focus sobre els fluxos de metalls i metal·loides derivats de l’abocament massiu de residus, sia d’origen industrial i urbà, com al prodelta del riu Besòs, o d’origen miner, com a la badia de Portmán. A més, amb l’objectiu de millorar la resolució de l’estudi i poder descriure en detall l’evolució temporal del flux de metalls i metal·loides, s’ha dut a terme l’anàlisi dels sediments a molt alta resolució mitjançant un escàner de fluorescència de raigs X (XRF core scanner). Aquest equipament permet obtenir una gran quantitat d’informació en molt poc temps, de manera no destructiva i amb resolucions impossibles d’aconseguir amb mètodes tradicionals de caràcter destructiu. Així doncs, s’ha desenvolupat un procediment de calibratge per transformar les mesures semiquantitatives de l’XRF core scanner a concentracions totals per diversos metalls i metal·loides (Ti, Mn, Fe, Zn, As i Pb). Els resultats demostren que els procediments analítics i estadístics desenvolupats en aquest treball milloren la qualitat de les regressions lineals, amb coeficients de correlació (r2) superiors a 0,94 i amb una reducció de les desviacions estàndards de les funcions obtingudes, especialment pel mètode de regressió ponderat de mínims quadrats (WLS). Això es tradueix en una minoració significativa dels errors associats a les concentracions calibrades de metalls i metal·loides, la qual cosa ha permès quantificar els llindars de concentració establerts en diverses guies de qualitat del sediment (Sediment Quality Guidelines, SQGs) amb un rang d’error de 0,4% a 2% pel Fe, 1% a 7% pel Zn, 3 a 14% pel Pb, i 5% a 16% pel Mn. Finalment, aquest procediment de calibratge ha estat aplicat a la caracterització física i geoquímica d’un dipòsit submarí altament contaminat generat per l’abocament de residus miners resultants de l’explotació de jaciments de sulfurs a la badia de Portmán. Mitjançant una metodologia que integra múltiples tècniques analítiques fisicoquímiques, sedimentològiques i de datació per 210Pb de testimonis de sediment, hom ha identificat sis fàcies sedimentàries: quatre pertanyents als residus miners sensu strictu (fàcies 2, 3, 4 i 5) i dues corresponents a sediments marins amb un cert grau de contaminació que predaten i postdaten el dipòsit de residus (fàcies 1 i 6). Els resultats obtinguts han permès explicar acuradament l’evolució del dipòsit de residus miners, el qual es concentra principalment al nord-oest de l’àrea d’estudi com a resultat no només de la ubicació del punt de descàrrega sinó també de la dinàmica sedimentària governada per l’efecte dominant de l’onatge de component est i sud-oest i els corrents litorals associats. De l’anàlisi geoquímica se’n desprèn que les concentracions de metalls i metal·loides al dipòsit de residus miners són molt superiors a les reportades en altres llocs de la mar Mediterrània. En els sediments superficials acumulats després de la finalització dels abocaments les concentracions de metalls i metal·loides són encara significativament superiors als valors naturals previs a l’activitat minera. Això, conjuntament amb la modelització numèrica de les concentracions i les distribucions de metalls i metal·loides en el sediment marí superficial (14 cm superiors), ha evidenciat l’existència d’un flux persistent cap als sediments més recents i cap al fons marí després de vint-i-cinc anys de la clausura de l’abocament de residus miners. Per tot plegat, aquesta Tesi contribueix, volem pensar que de manera significativa, a la millora de les metodologies d’estudi dels fluxos de metalls i metal·loides, i de determinació i quantificació de llurs concentracions i distribucions al medi marí costaner. L’esforç d’integració metodològica desenvolupat en aquesta Tesi ha permès assolir una millor comprensió dels processos de contaminació i de pol·lució, i demostra que l’ús integrat de diverses metodologies és clau per a la millora dels programes i actuacions de gestió ambiental que permetin reduir els fluxos de metalls i metal·loides d’origen antropogènic cap a l’oceà i els seus efectes sobre l’ecosistema costaner.
El estudio de la concentración y la distribución de metales y metaloides en ambientes costeros, ha adquirido relevancia en los último cuarenta años, principalmente como consecuencia de la creciente preocupación por sus efectos nocivos sobre los ecosistemas y la salud pública. Los ciclos de los metales y metaloides, con una gran cantidad de variables físicas, químicas, biológicas y también antropogénicas que influyen, son extremadamente complejos, circunstancia que dificulta su comprensión. Por este motivo, la mejora de las metodologías y la aplicación de nuevas técnicas de estudio es fundamental para poder profundizar en el conocimiento de los procesos asociados a la contaminación y la polución del océano por metales y metaloides. En este contexto, esta Tesis representa una contribución al desarrollo y a la integración de las metodologías disponibles para el estudio de los flujos de metales y metaloides de origen antropogénico hacia el medio marino. Para alcanzar este objetivo, la Tesis se ha centrado en el estudio de dos vías de entrada de metales y metaloides hacia el mar costero: las descargas de agua subterránea (DAS) y el vertido directo de residuos en dos áreas de la costa mediterránea, la costa central de Cataluña y la bahía de Portmán, en Murcia. En primer lugar, se han abordado las metodologías de cuantificación de las DAS mediante isótopos de Ra y 222Rn. El análisis y el monitoreo de los isótopos de Ra en el acuífero aluvial de la riera de Argentona, durante dos años ha demostrado que la variabilidad observada en sus concentraciones, de más de un orden de magnitud, está gobernada por el desplazamiento de la posición de la interfase salina durante períodos de precipitaciones abundantes. La variabilidad registrada en las concentraciones de los isótopos dificulta la determinación de un valor representativo de Ra en el acuífero, lo cual es un requisito necesario para cuantificar los flujos de DAS. Puesto que los flujos de metales y metaloides derivados de las DAS aumentan significativamente durante los episodios de precipitaciones, la elevada dinámica de los acuíferos costeros en regímenes micromareales hace necesario un mejor conocimiento de los procesos hidrogeológicos locales o regionales para poder reducir las incertidumbres asociadas a la cuantificación de los flujos de metales y metaloides hacia los sistemas costeros. En segundo lugar, la Tesis sitúa el foco sobre los flujos de metales y metaloides derivados del vertido masivo de residuos, sean estos de origen industrial y urbano, como en el prodelta del río Besós, o de origen minero, como en la Bahía de Portmán. Además, con el objetivo de mejorar la resolución del estudio y poder describir en detalle la evolución temporal del flujo de metales y metaloides, se ha llevado a cabo el análisis de los sedimentos a muy alta resolución mediante un escáner de fluorescencia de rayos X (XRF core scanner). Este instrumento permite obtener una gran cantidad de información en muy poco tiempo, de modo no destructivo y con una resolución imposibles de conseguir con métodos tradicionales de carácter destructivo. Así pues, se ha desarrollado un procedimiento de calibración para transformar las medidas semicuantitativas del XRF core scanner en concentraciones totales para diversos metales y metaloides (Ti, Mn, Fe, Zn, As y Pb). Los resultados demuestran que los procedimientos analíticos y estadísticos desarrollados en este trabajo mejoran la calidad de las regresiones lineales, con coeficientes de correlación (r2) superiores a 0,94 y con una reducción de las desviaciones estándares de las funciones obtenidas, especialmente por el método de regresión ponderado de mínimos cuadrados (WLS). Esto se traduce en una minoración significativa de los errores asociados a las concentraciones calibradas de metales y metaloides, lo cual ha permitido cuantificar los umbrales de concentración establecidos en diversas guías de calidad del sedimento (Sediment Quality Guidelines, SQGs) con un rango de error de 0,4% a 2% para el Fe, 1% a 7% para el Zn, 3 a 14% para el Pb, y 5% a 16% para el Mn. Finalmente, se ha aplicado este procedimiento de calibración a la caracterización física y geoquímica de un depósito submarino altamente contaminado generado por el vertido de residuos mineros resultantes de la explotación de yacimientos de sulfuros en la bahía de Portmán. Mediante una metodología que integra múltiples técnicas analíticas fisicoquímicas, sedimentológicas y de datación por 210Pb de testigos de sedimento, se han identificado seis facies sedimentarias: cuatro pertenecientes a los residuos mineros sensu strictu (facies 2, 3, 4 y 5) y dos correspondientes a sedimentos marinos con un cierto grado de contaminación que pre-datan y post-datan el depósito de residuos (facies 1 y 6). Los resultados obtenidos han permitido explicar la evolución del depósito de residuos mineros, el cual se concentra principalmente al noroeste del área de estudio debido no sólo a la ubicación del punto de vertido si no también a la dinámica sedimentaria gobernada por el efecto dominante del oleaje de componente este y sudoeste y por las corrientes litorales asociadas. Del análisis geoquímico se desprende que las concentraciones de metales y metaloides en el depósito de residuos mineros son muy superiores a las reportadas para otros lugares del Mar Mediterráneo. En los sedimentos superficiales acumulados posteriormente al cese de los vertidos las concentraciones de metales y metaloides son aún significativamente superiores a los valores naturales previos a la actividad minera. Esto, junto con la modelización numérica de las concentraciones y las distribuciones de metales y metaloides en el sedimento marino superficial (14 cm superiores), ha puesto de manifiesto la existencia de un flujo persistente hacia los sedimentos más recientes y hacia el lecho marino después de veinticinco años de la clausura de los vertidos de residuos mineros. Per todo lo expuesto, esta Tesis contribuye, queremos pensar que de manera significativa, a la mejora de las metodologías de estudio de los flujos de metales y metaloides, y de determinación y cuantificación de sus concentraciones y distribuciones en el medio marino costero. El esfuerzo de integración metodológica desarrollado en esta Tesis ha permitido alcanzar una mejor comprensión de los procesos de contaminación y de polución, y demuestra que el uso integrado de diversas metodologías es clave para la mejora de los programas y actuaciones de gestión ambiental que permitan reducir los flujos de metales y metaloides de origen antropogénico hacia el océano, así como sus efectos sobre el ecosistema costero.
The study of the concentration and distribution of metals and metalloids in coastal environments has gained interest in the last forty years, mainly due to the growing concern about their harmful effects on the ecosystems and public health. Even so, the elevated complexity of the metals and metalloids cycles, which are influenced by numerous physical, chemical, biological and anthropogenic variables, makes their understanding difficult. Because of this, improving the state of the art methodologies and applying new techniques is essential to achieve a better knowledge of the processes associated with marine pollution by metals and metalloids. In this context, this PhD Thesis represents a contribution to the development and integration of methodologies for the study of anthropogenic-sourced fluxes of metals and metalloids into the sea. To achieve this objective, the Thesis is focused in the study of two type of pathways of metals and metalloids fluxes to the coastal sea: submarine groundwater discharges (SGD) and direct waste disposal in two areas of the Iberian Mediterranean coast, which are the central coast of Catalonia and Portmán Bay, in Murcia. Firstly, the Thesis addresses the methodologies for quantifying SGD using Ra and 222Rn isotopes. The analysis and monitoring of Ra isotopes in the alluvial aquifer of the Argentona torrent during two years has shown that the variability of their concentrations, which is more than one order of magnitude, is mainly governed by the displacement of the saline interface during heavy rain periods. The recorded variability of the isotopic concentrations makes difficult determining a representative value of Ra in the aquifer, which is a requirement to quantify SGD. Given the significant increase of SGD metals and metalloids fluxes derived during heavy rain events, the high dynamics of coastal aquifers in microtidal regimes imposes a better knowledge of the hydrogeological processes at local or regional scales in order to reduce the uncertainties associated with the quantification of such fluxes in coastal systems. Secondly, this PhD Thesis focuses in metals and metalloids fluxes from massive coastal waste accumulations, whether they result from mining activities, as in Portmán Bay, or from industrial and urban sources, as in the Besòs River prodelta off Barcelona city. To improve the fineness of analysis needed to carefully describe the temporal evolution of metal and metalloids fluxes, we have carried out high-resolution measurements of the sediments by means of a XRF core scanner. This equipment produces huge amounts of data within a reduced time of analysis, in a non-destructive way and with resolutions that are unachievable by traditional, sample destructive methods. A calibration procedure has been developed to transform the semi-quantitative measurements from the XRF core scanner into total concentrations of various metals and metalloids (Ti, Mn, Fe, Zn, As and Pb). The results demonstrate that the analytical and statistical procedures developed in this study improve the quality of linear regressions, with correlation coefficients (r2) above 0.94 and a reduction of standard deviations, especially when applying the weighted least squares regression method (WLS). This translates into a reduction of errors associated with the calibrated concentrations of metals and metalloids, which allows quantifying the concentration thresholds defined by various sediment quality guides (SQG) with an error range of 0.4% to 2% for Fe, 1% to 7% for Zn, 3% to 14% for Pb and 5% to 16% for Mn. The same calibration procedure has been applied to the physical and geochemical characterization of a highly polluted marine deposit originated by the dumping of mining wastes in Portmán Bay. The application of multiple analytical physicochemical, sedimentological and 210Pb dating techniques to a large set of short sediment cores allowed identifying six main sedimentary facies, four of which correspond to the mine tailings sensu strictu (facies 2, 3, 4 and 5) and two to contaminated marine sediments that predate (facies 1) and postdate (facies 6) the mine tailings deposit. The results allow explaining the evolution of the mine tailings deposit, which mainly concentrate into the northwest corner of the study area as a consequence not only of the location of the discharge point but also of the sedimentary dynamics governed by the dominant effect of an easterly and southwesterly wave pattern and associated littoral currents. The analyses show that the metals and metalloids concentrations in the main tailings facies are significantly higher than those commonly found in other regions of the Mediterranean Sea. Within the top layer of sediments, which formed following the cessation of waste disposal, the concentration of metals and metalloids is less but still is significantly higher than background natural values prior to mining activities. This data, together with the numerical modeling of the concentrations and distribution of metals and metalloids in the uppermost layer of marine sediments (top 14 cm), evidences a persistent flow to the most recent sediments and the seafloor twenty-five years after the closure of mine waste discharge. Finally, the outcomes of this Thesis involve a significant improvement of the methodologies applied to the study of metal and metalloid fluxes to the marine coastal environment, and also on the determination and quantification of their concentrations and distributions. The major effort for methodological integration carried out in this Thesis has led to a better understanding of the processes controlling those fluxes and the ensuing contamination and pollution effects. We think that we have also proven that the integrated used of complementary methodologies is critical for improving environmental management programs and actions aimed at reducing the fluxes of anthropogenic metals and metalloids to the ocean and their deleterious effects on marine coastal ecosystems.

O presente trabalho apresenta os resultados obtidos na avaliação dos problemas ambientais relacionados a lixiviação de poluentes do lixão próximo ao Ribeirão dos Moinhos na cidade de Poços de Caldas (MG). O estudo considera as características geológicas - geotécnicas e climáticas da área e os vários tipos de técnicas de \"cleanup\". O software Visual Modflow foi usado para desenvolver simulações em termos de fluxo de água subsuperficial e de transporte de poluentes.
This work presents the results obtained from assessment of the environment problems related to the pollutant lixiviation from the urban wastes disposed near the Moinho River in Poços de Caldas (MG) city. The study considered the geological - geotechnical and climatic characteristics of the area and the main kinds of cleanup techniques. The software Visual Modflow were used to developed the simulation in terms of groundwater flow and pollutant transport.