The fault-bounded Cianzo basin represents a Cenozoic intermontane depocenter between the Puna plateau and Eastern Cordillera of the central Andean fold-thrust belt in northern Argentina. New characterizations of fold-thrust structure, nonmarine sedimentation, and sediment provenance for the shortening-induced Cianzo basin at 23°S help constrain the origin, interconnectedness, and subsequent uplift and exhumation of the basin, which may serve as an analogue for other intermontane hinterland basins in the Andes. Structural mapping of the Cianzo basin reveals SW and NE-plunging synclines within the >6000 m-thick, upsection coarsening Cenozoic clastic succession in the shared footwall of the N-striking, E-directed Cianzo thrust fault and transverse, NE-striking Hornocal fault. Growth stratal relationships within upper Miocene levels of the succession indicate syncontractional sedimentation directly adjacent to the Hornocal fault. Measured stratigraphic sections and clastic sedimentary lithofacies of Cenozoic basin-fill deposits show upsection changes from (1) a distal fluvial system recorded by vi fine-grained, paleosol-rich, heavily bioturbated sandstones and mudstones (Paleocene‒Eocene Santa Bárbara Subgroup, ~400 m), to (2) a braided fluvial system represented by cross-stratified sandstones and interbedded mudstones with 0.3 to 8 m upsection-fining sequences (Upper Eocene–Oligocene Casa Grande Formation, ~1400 m), to (3) a distributary fluvial system in the distal sectors of a distributary fluvial megafan represented by structureless sheetflood sandstones, stratified pebble conglomerates and sandstones, and interbedded overbank mudstones (Miocene Río Grande Formation, ~3300 m), to (4) a proximal alluvial fan system with thick conglomerates interbedded with thin discontinuous sandstone lenses (upper Miocene Pisungo Formation, ~1600 m). New 40Ar/39Ar geochronological results for five interbedded volcanic tuffs indicate distributary fluvial deposition of the uppermost Río Grande Formation from 16.31 ± 0.6 Ma to 9.69 ± 0.05 Ma. Sandstone petrographic results show distinct upsection trends in lithic and feldspar content in the Casa Grande, Río Grande, and Pisungo formations, potentially distinguishing western magmatic arc (Western Cordillera) sediment sources from evolving eastern thrust-belt sources (Puna‒Eastern Cordillera). In addition to growth stratal relationships and 40Ar/39Ar constraints, conglomerate clast compositions reflect distinct lithologic differences, constraining the activation of the Cianzo thrust and coeval movement on the reactivated Hornocal fault. Finally, U-Pb geochronological analyses of sandstone detrital zircon populations in conjunction with paleocurrent data and depositional facies patterns help distinguish localized sources from more distal sources west of the basin, revealing a systematic eastward advance of Eocene to Miocene fold-thrust deformation in the central Andes of northern Argentina. / text

Η περιοχή μελέτης εκτείνεται στο βόρειο και παραλιακό τμήμα του νομού Κορινθίας μεταξύ των πόλεων Κιάτου και Κορίνθου και καταλαμβάνει έκταση 65km2. Η νέα εθνική οδός Κορίνθου – Πατρών αποτελεί το νότιο όριο της περιοχής ενώ προς βορρά περιορίζεται από τον Κορινθιακό κόλπο. Το τοπογραφικό ανάγλυφο είναι ήπιο με το υψόμετρο να κυμαίνεται από 0 – 50 μέτρα. Ο ποταμός Ασσωπός και οι χείμαρροι Ραχιάνης και Ζαπάντης δομούν το υδρογραφικό δίκτυο της περιοχής. Το γεωλογικό υπόβαθρο της περιοχής αποτελείται από ανθρακικά ιζήματα των ζωνών Τρίπολης και Πίνδου, των οποίων υπέρκεινται μετα-ορογεντικά ιζήματα Πλειο-πλειστοκαινικής ηλικίας. Ο υδροφόρος ορίζοντας που μελετήθηκε αναπτύσσεται σε αλλουβιακά ιζήματα, κυρίως άμμους, κροκάλες, λατύπες, και λεπτομερή αργιλοαμμώδη και πηλοαμμώδη ιζήματα που εμφανίζουν υψηλό βαθμό ετερογένειας. Το πάχος του υδροφόρου κυμαίνεται από λίγα μέτρα έως 60 m και χαρακτηρίζεται ως ελεύθερος. Η ρηξιγενής ζώνη που εμφανίζεται κατά μήκος της Ν.Ε.Ο. Κορίνθου – Πατρών αποτελεί υδρογεωλογικό όριο προς νότο για τον υπό μελέτη υδροφόρο. Η εμφάνιση μαργών στην περιοχή του Κιάτου είναι το δυτικό υδρογεωλογικό όριο, ενώ ανατολικά περιορίζεται από την επέκταση των Τυρρήνιων αναβαθμίδων στη θάλασσα. Η κύρια τροφοδοσία του υδροφόρου προέρχεται από τη διήθηση των επιφανειακών υδάτων του ποταμού Ασωπού και των παρακείμενων χειμάρρων, ενώ κατά δεύτερο λόγω από την απευθείας κατείσδυση των ατμοσφαιρικών κατακρημνισμάτων. Για την προσομοίωση της υπόγειας ροής του αλλουβιακού υδροφόρου έγινε χρήση του κώδικα MODFLOW της USGS. Από την εφαρμογή του μοντέλου εξήχθησαν ικανοποιητικά αποτελέσματα που έδωσαν τη δυνατότητα υπολογισμού ενός αξιόπιστου ισοζυγίου, το οποίο μπορεί να αποτελέσει ένα εργαλείο στην εφαρμογή ενός σχεδίου ορθολογικής διαχείρισης των υδατικών πόρων της Κορινθίας. Για την υδροχημική έρευνα χρησιμοποιήθηκε πυκνό δίκτυο δειγματοληψίας νερού σε 35 υδροσημεία της περιοχής μελέτης. Ο υδροφόρος έχει επηρεαστεί από φαινόμενα υφαλμύρινσης και ανταλλαγής ιόντων κυρίως στις βόρειες παράκτιες ζώνες. Οι συγκεντρώσεις των NO3-, NH4+ και των SO4-2 ιόντων παρουσιάζονται υψηλότερες από τα ανώτατα επιτρεπόμενα όρια ποσιμότητας. Η εφαρμογή της παραγοντικής ανάλυσης ανέδειξε τις παραπάνω υδροχημικές διεργασίες. / The study area forms the northern coastal part of Corinth’s prefecture, between the towns of Kiato and Corinth and has an area extend of 65 km2. To the south it is bounded by Athens - Patras National road, whilst to the north it is bounded by Corinthian Gulf. The topographic relief is quite gentle and varies from 0 to 50 m. A considerable hydrographic network develops across the studied region and is represented mainly by the river Asopos and the less important torrents Rachianis and Zapantis. The region can be characterized as an agro tourism center. The land is used mainly for the cultivation and of citrus fruits, olives, apricots and vineyards. Regional environment is subject to numerous pressures most important of which are intensified uses of land and water resources. Water demands have considerably increased over the last 15 years and mainly are covered by groundwater abstract from the alluvial aquifer system. The geological bedrock of the study area consists of the carbonate sediments of Tripolis and Pindos isopics zones and a transitional zone between Pindos and Pelagonial Zone. The plain north of the national zone is covered by post orogenetic sediments of Pliocene to Holocene age which unconformably overlay the bedrock formations. The studied aquifer is formed of recent unconsolidated material consisting of sands, pebbles, breccias and fine clay to silty sand deposits, characterized by high degree of heterogeneity and anisotropy. The thickness of the aquifer varies from a few meters to 40 m. From a hydrogeological point of view the system consists of an unconfined phreatic aquifer. A fault zone along the national highway delineates the southern edge of aquifer system, which is bounded by the Gulf of Corinth to the north. To the east, the system is bounded by the Tyrrhenian deposits extended to the sea. The marl series which, as an entity, is considered an aquitard, slopes to the north and forms the bedrock of the studied coastal alluvial aquifer system. The basic recharge of the phreatic aquifer is from the fluviotorrential deposits, especially those of the Asopos River and also from the Tyrrhenian deposits across the southern edge of the basin. In addition to that the aquifer recharged from direct infiltration of precipitation and river bed indirect infiltration. The simulation of ground water flow of the alluvial aquifer is based on the MODFLOW model of the USGS. The application of the mathematical model had very satisfactory results which is a reliable hydrogeological balance. Estimation of hydraulic conductivity distribution was optimized by using trial and error inverse method. The ground water hydrochemical study was carried out, by an extensive network of 35 samples. The use of inorganic fertilizers in cultivations has a great pollution effect in ground water. The coastal aquifer has been affected, by sea water intrusion and as a result catio-exchange phenomena took plase along the coastline mainly at Lechaio area. The concentration of NO3- , NH4+, and SO4- ions are higher than the maximum allowed drinking limits. The application of R-mode factor analysis helped to delineate the major hydrochemical process of the area.

Les aménagements hydrauliques du Rhin ont fortement modifié le fonctionnement hydrologique des zones alluviales et provoqué la déconnexion de la plupart des bras du Rhin et des forêts alluviales. Des opérations de ré-inondation des secteurs déconnectés du fleuve ont été menées dans un objectif à la fois de rétention de crue et de submersion écologique qui devraient permettre à ces zones de retrouver tout ou partie de leur fonctionnalité. Le polder d'Erstein est un secteur forestier expérimental pour le suivi de l'impact des ré-inondations des zones alluviales. Les inondations du polder par les eaux de Rhin sont susceptibles d'en modifier le fonctionnement hydrologique (écoulements de surface, échanges nappe-rivière, recharge de la nappe ...). L'objectif général de ces recherches est l'analyse et la quantification des transferts hydriques dans un aquifère poreux dans un contexte de ré-inondation. Pour ce faire nous avons réalisé des simulations numériques de l'écoulement à l'aide du code de calcul Feflow (Finite element subsurface flow system), qui ont été validées par les données hydrogéologiques mesurées in situ. Ce travail est organisé en cinq volets. Le point de départ est un état de l'art du fonctionnement, de la structure des zones alluviales et des mécanismes du transfert hydrique dans ces zones. La deuxième partie, fournit une présentation détaillée du site expérimental sur lequel une mission de suivi scientifique a débuté en 2003 et ainsi fourni une importante base de données hydrologiques (eaux de surface et eaux souterraines). Ces données ont servi à caractériser les écoulements d'eau en zone non saturée. La troisième partie est consacrée à la construction du modèle hydrodynamique. Compte tenu de l'importance du réseau des anciens bras du Rhin alimentées par la nappe existant à l'intérieur du polder, la question des échanges cours d'eau-nappe a été abordée. Hormis la recharge de la nappe par les cours d'eau, une part importante de l'infiltration d'eau depuis la surface du sol lors des inondations contribue à la recharge. Pour quantifier cette part, nous avons développé une approche pédologique originale afin de caractériser les hétérogénéités des sols par des paramètres hydrodynamiques. Ces hétérogénéités qui varient spatialement sur le polder ont une influence significative sur les flux verticaux et les temps de résidence de l'eau dans la zone non saturée. Les résultats obtenus en 1D ont ensuite été appliqués à toute la superficie du polder d'Erstein avec l'objectif de quantifier l'ensemble des écoulements à cette échelle. Différents scénarios d'hétérogénéité proposés se fondent sur une complexification de la structure de l'aquifère poreux, afin d'évaluer l'impact des hétérogénéités du sol sur le transfert hydrique dans le polder d'Erstein.

Submitted by Johnny Rodrigues (johnnyrodrigues@ufcg.edu.br) on 2018-09-05T18:25:04Z No. of bitstreams: 1 HUGO MORAIS DE ALCÂNTARA - DISSERTAÇÃO PPGECA 2007..pdf: 2937576 bytes, checksum: 4120665ff013d35f135ab12cfe7ca9a5 (MD5) / Made available in DSpace on 2018-09-05T18:25:04Z (GMT). No. of bitstreams: 1 HUGO MORAIS DE ALCÂNTARA - DISSERTAÇÃO PPGECA 2007..pdf: 2937576 bytes, checksum: 4120665ff013d35f135ab12cfe7ca9a5 (MD5) Previous issue date: 2007-03-29 / O presente trabalho tem o objetivo de avaliar a natureza da variação da resistência total em canais aluviais e propor uma função de resistência total. A partir da equação fundamental da resistência da superfície, é definida uma função cuja variação pode ser associada aos efeitos da forma do leito e da distribuição granulométrica de sedimentos. A forma desta função, obtida através de análise dimensional utilizando a técnica de regressão linear múltipla, é apresentada para sedimentos unimodais e bimodais associada a cada tipo de canal e mistura de sedimentos. Foi utilizada uma grande massa de dados experimentais de laboratório e de campo coletados por diversos pesquisadores em vários estudos. Com base nos diversos estudos encontrados na bibliografia e considerando as incertezas envolvidas na separação da resistência total em, a resistência devido aos grãos na superfície e das formas do leito, decidiu-se propor uma função de resistência separadamente para cada forma do leito para o parâmetro de resistência B. A grande vantagem da metodologia proposta é que esta avalia a resistência total do leito sem a necessidade de separação dos efeitos dos grãos e das formas do leito. Os resultados mostram que uma excelente relação funcional pode ser estabelecida para cada forma do leito e mistura de sedimentos utilizando três e dois parâmetros adimensionais. O efeito da distribuição granulométrica dos sedimentos ficou evidenciado no caso do leito plano e com sedimentos bimodais, indicando que nos casos em que a distribuição natural – log-normal – de sedimentos não seja aplicável, o efeito da distribuição granulométrica é significativo na resistência total do canal aluvial. / The present work has the objective of evaluating the variation of the hydraulic resistance in alluvial channels and propose a function of total resistance. Starting from the fundamental concept of the resistance of the surface, a function is defined in which the variation of resistance can be associated with the characteristics of the bed form and the grain size distribution of the mixture of the sediments in the bed. The form of this function, obtained through dimensional analysis using the technique of multiple linear regression, is presented for unimodal and bimodal sediments associated with each channel type and mixture of sediments. Utilizing the data collected by various researchers in laboratory canals and rivers, the functional relationships for the resistance factor, here in identified as a dimensionless factor “B”, has been established utilizing three, or in a simple form, two, dimensionless parameters as independent variables. The great advantage of the resistance function proposed here is that it eliminates the need to separate the total resistance into two components. The results show that an excellent functional relationship can be established for each bed form and mixture of sediments using three parameters. The influence of the grain size distribution of the sediments was evidenced in the case of all the bed forms and especially bimodal sediments. In the cases of natural distribution (log-normal) of sediments in the sand range, the effect on the individual grain size distributions became hardly noticeable.

Common behavioral trends and characteristics of alluvial channels including rivers are extensively discussed in the literature. However, little is known about the hydrodynamic effects of seepage on alluvial channels. Factors like sand bed resistance, stream power of the channel, incipient motion of bed particles, and geometry of the channel cross section are significantly affected by seepage. This thesis presents the experimental investigations that are aimed to find out the quantitative effect of seepage, through a sand bed in downward (suction) direction, on the above mentioned factors. The problem in the sediment transport analysis is that the knowledge of complex interaction of several parameters with seepage cannot be fully obtained. In order to generalize the results, experiments are conducted in four rectangular smooth walled sand bed flumes under steady and fairly uniform flow conditions. Among the four, one is the Large Tilting Flume (LTF), which is 25 m long, 1.80 m wide and 1.00 m deep and with a seepage length of up to 20 m. This LTF is specially built at hydraulic laboratory, Indian Institute of Science exclusively for the present research work especially on alluvial channel regime. The experimental channels are designed to apply controlled amounts of uniform seepage flow in either direction in one flume (Flume-2), and only in downward direction to other three flumes (Flumes 1, 3 and 4). The application of seepage is perpendicular to the sand bed thickness over a sufficient length of the main channel. Appropriate instruments are used to accurately measure the basic experimental variables such as discharge in the main channel, seepage discharge, flow depth, water surface and bed slope, seepage gradients and cross sectional profiles. Experiments are carried out at different conditions (plane beds and curved shape channels) as explained below: Plane sediment beds Series – 1: Experiments to determine incipient motion of bed particles under no-seepage condition. Series – 2: Experiments on the non-transporting condition of the bed particles under both no-seepage and seepage condition. Series – 3: Experiments on the transporting condition of the bed particles under both no-seepage and seepage condition. Curved shape channels Series – A: Experiments to verify Lane’s (1953) geometric profile against higher discharge than prescribed by Lane (1953). Series – B: Experiments to verify the Lane’s (1953) geometric profile by allowing the discharge prescribed by Lane (1953). Series – C: Experiments to predict the final geometric profile by applying suction to Series – B experiments. A wide range of sediment particles are tested. Five different sized uniform sands (d50 = 1 mm, 0.56 mm, 0.65 mm, 1.00 mm and 1.77 mm) and gravel of size d50 = 8.00 mm are used for experimentation. Among the six sizes, three sizes (d50 = 0.56 mm, 0.65 mm, 2 mm) are used for seepage experimentation. The experimental data from the present experiments along with the available data from other sources on more sizes of sand are analyzed, thus covering a wide range of sand sizes. The following important results are obtained from the analysis. A new resistance equation has been developed for plane sediment beds (with little or no-transport) such that the average velocity in the channel depends on the shear velocity Reynolds number. A careful study has been done on incipient motion and concluded that incipient motion is better explained by critical stream power criterion for plane sediment beds. With the help of critical stream power criterion, a straightforward design procedure using design tables/design curves and analytical methods are presented to solve six possible design problems. For plane and non-transporting beds, in general, the stream power in the channel increases with suction and decreases with injection. The increase and decrease depend on the seepage power intensity parameter (NP), initial value of stream power (Ωbo), and critical stream power of the particles under no-seepage condition (Ωco). An expression relating all the influencing parameters is established to quantitatively estimate the stream power (Ωbs) variation with both the types of seepages, i.e., with suction and injection. It is found that the seepage has a significant influence in changing critical stream power for incipient motion of the bed material and the value is significantly different from the no-seepage critical value. An expression is established to quantitatively estimate the critical stream power with seepage (upward and downward) for a given critical stream power (Ωco) of the bed material under no-seepage conditions and initial stream power (Ωbo). It has been established that critical stream power curve used to define incipient motion is valid only for no-seepage condition of the bed and it cannot be used for sand beds under seepage condition, as seepage effects significantly alters the stream power. From the wide range of experimental data (including the observations from LTF) it is found that suction (downward seepage through the sand bed) enhances the transport or aids the incipient motion of bed particles which are initially at rest. Thus, suction reduces the stability and increases the erosion of bed particles when compared to no-seepage conditions. However, it is found that injection (upward seepage) affects in an opposite way, i.e., it can reduce the transport rate or even inhibit the incipient motion. Thus, injection increases the stability and reduces the erosion of bed particles when compared to no-seepage conditions. Therefore, it is concluded that suction increases the mobility of sand particles where as injection decreases their mobility. An expression to find the incipient motion with seepage (both suction and injection) is established in terms of stream power’s (Ωco, Ωbo and Ωbs) based on the present experimental data along with others' data. With the help of these expressions design procedure is developed for ten types of possible problems. A numerical model for spatially varied flow has been developed with the help of the seepage governing equations, developed in this thesis, to compute flow profiles along the channel length. A methodology of predicting the location of incipient motion section in sand bed channels affected by seepage is also presented. Channel geometry affected by seepage (suction) is established in the form of regression relationships for perimeter, flow depth and slope of the channel. Different combinations (bi-variate and tri-variate) of dimensional and non-dimensional regression relationships are developed. An approach to channel design has been developed based on the application of functional analysis of the salient variables that control the channel behavior. And also, it has been established that, Lane’s (1953) profile almost matches with experimental profile for no-seepage condition. The present investigation clearly shows the significance of seepage in altering the hydraulic and sediment transport behavior of sand bed channels. From the practicing engineer’s point of view it is hoped that present design procedures will be helpful in safe guarding the seepage affected channels.

Dans un champ captant, comme celui qui alimente l'agglomération lyonnaise, le fonctionnement de chaque « objet » (bassins d'infiltration, puits, rivières, nappe, zone non saturée) et leurs interactions sont complexes et mal connus. Dans un premier temps, une série d'essais d'infiltration à différentes échelles dans un bassin artificiel de réalimentation a permis de mieux appréhender le fonctionnement de cet ouvrage et de chiffrer les paramètres hydrodynamiques de la zone non saturée. Les résultats des interprétations par méthodes numériques fondées sur l'équation de Richards ont montré que les flux infiltrés dans les bassins dépendent principalement de la conductivité hydraulique à saturation d'une couche située directement sous le sable calibré couvrant le fond du bassin, identifiée comme étant moins perméable que la nappe. Cette couche conditionne l'existence d'une zone non saturée. La réalisation d'essais de pompage dans l'aquifère sur les forages d'exploitation et sur un dispositif spécialement mis en place durant ce travail a permis de déterminer les paramètres hydrodynamiques de la nappe. Une analyse des observations et une modélisation conceptuelle en 2D, puis en 3D ont permis d'identifier les mécanismes prépondérants (stratifications, apports et prélèvements) et de simuler correctement à la fois les flux infiltrés dans un des bassins d'infiltration et la remontée de la nappe. A l'échelle d'un bassin, les flux infiltrés sont variables dans le temps, ils dépendent de l'état de colmatage de la surface d'infiltration mais également de la température de l'eau infiltrée et de l'état hydrique initial du sol sous le bassin. Les analyses de sensibilité réalisées avec les modèles mis en place indiquent que la conductivité hydraulique à saturation de l'aquifère, mais également la proximité des conditions aux limites imposées dans la nappe (les rivières et les puits de pompage) influencent de manière prépondérante la remontée de la nappe. Une modélisation 3D d'un autre secteur du champ captant comprenant deux bassins d'infiltration, deux bras de rivière ainsi que des puits de pompage a été réalisée. La condition à la limite imposée sur les rivières est du troisième type en accord avec l'observation d'un sous-écoulement en nappe. Les échanges nappe/rivières sont calés sur des observations à partir d'une chronique de propagation d'une onde de crue dans la nappe. Des piézomètres en flûte de pan, spécifiquement implantés à proximité d'un bassin, ont permis d'observer des différences de charge hydraulique fortes à différents niveaux de l'aquifère lorsque le bassin d'infiltration est en eau. La modélisation 3D est conforme à ces observations. Elle a confirmé l'importance du rôle d'une hétérogénéité de type argilo-sableuse (de conductivité hydraulique à saturation inférieure aux autres lithologies présentes dans l'aquifère) dans les écoulements (direction et flux). Le modèle développé représente correctement les flux infiltrés via les bassins ainsi que les fluctuations de la piézométrie de la nappe. Il permet de vérifier l'inversion des écoulements par rapport aux infiltrations de la rivière, d'identifier les puits alimentés par les bassins d'infiltration et également de mettre en évidence les flux de nappe passant sous la rivière. / In a well field of the Lyon metropolitan area, designed for drinking water supply, behaviour of each object (infiltration basins, wells, rivers, aquifer, and unsaturated zone) and their interactions are complex and not well-known. As a first step, infiltration tests at different spatial scales in one artificial basin were performed to better understand the basin operation and to estimate the hydrodynamic parameters of the unsaturated zone. Results of interpretation, using numerical methods based on Richards equation, reveal that infiltrated basin fluxes mainly depend on saturated hydraulic conductivity of a layer located just below the calibrated sand layer that cover the basin bottom. Indeed this layer has been estimated to be less permeable than the aquifer, which allows the existence of the unsaturated zone below. Pumping tests in the groundwater have been performed using production wells and a well specially implemented during this thesis work in order to estimate aquifer hydrodynamic parameters. Observations analysis and a conceptual modelling, in 2D and then in 3D, lead to a better understanding of the controlling mechanisms (stratification, input and output) and to simulate both basin infiltration rates and water table rise. Considering the whole basin scale, input fluxes are transient, related to the clogging statement of the infiltration area but also to the temperature of inflow water and the initial statement of the soil just below the basin. Sensibility analyses using the models highlight that the amount of the water table rise is mainly influenced by the aquifer saturated hydraulic conductivity and also by the location of imposed boundaries in the aquifer (rivers and pumping wells). The model properly accounts basin inflow fluxes and water table fluctuations. The model is able to verify if flows are reversed in relation to river exchanges, if wells are fed by infiltration basins and it highlights aquifer flows below the river. A 3D modelling has been realised in another area of the well field, comprising two infiltration basins, two river arms and pumping wells. In agreement with underflow in the aquifer, rivers are imposed in the model as third kind boundary conditions. Aquifer and river exchanges are calibrated with observed data of one aquifer flood-wave propagation. Significant differences of hydraulic heads have been observed at different depths of the aquifer using panpipes piezometers, specifically implemented, close to one infiltration basin. Theses differences are closely related to basin operation. These observations are properly calculated by the 3D model. Using the model, the effect of one sandy-clay heterogeneous layer (whose saturated hydraulic conductivity is lower than the ones of other aquifer lithologies) on aquifer flows (direction and flux) is notable. The model properly accounts basin inflow fluxes and water table fluctuations. The model is able to verify if flows are reversed in relation to river exchanges, if wells are fed by infiltration basins and it highlights aquifer flow below the river.

Made available in DSpace on 2014-07-29T12:05:40Z (GMT). No. of bitstreams: 1 Roberto Prado Morais Tese Doutorado.pdf: 1346460 bytes, checksum: 7a4d11cce03206de064b40ceb41748dd (MD5) Previous issue date: 2006-05-29 / The Araguaia River is the most important fluvial system of South America. With an area of 380.000Km², it´s includes two phytogeography regions that have a good part of planet biodiversity: Cerrado, in the south, and Amazonia Forest, in the north of Brazil. The high level of Cerrado ecosystem destruction and changes in the land using, after 1965, promoted an intense sedimentation in fluvial system. This study is about the channel of Araguaia river, in a 580 km extension, between the city of Barra do Garças (MT) and the confluence of Cristalino and Araguaia Rivers. The multidisciplinary approach of this study has as aim analyze the channel geomorphic and middle reach alluvial plains processes causing environmental changes to the channel morphology and to vegetation succession, done by the erosive and sedimentary processes in the channel. The quantitative data were obtained through maps, air photographs and topographic charts from Landsat 1 MMS (1975) and Landsat 5 TM (1998). Using geoprocessing recourses were done areal reports of erosive and sedimentary plans and were applied mathematics equations to estimate sediments bulk and mass remobilized and stored in fluvial system. Were obtained also socioeconomics information about the Araguaia River basin area in Goiás, during the decades of 1960 and 2000, the cities of this same basin s GDP, the cattle growing statistics, vegetation and deforestation areas. The physical and socioeconomic data showed a correlation between the emergence of geomorphologic processes that had modified the channel, with the growth and development socioeconomics activities. The gotten results had disclosed that between 1965 and 1975, few changes had occurred in the fluvial channel. After 1975, a sped up erosion process of the channel edges and of islands has beginning, mobilizing the sediments, the bigger vegetation, as arboreal and bush arboreal type, that are associates to the oldest units of alluvial plain. With greater arrives of sediments that had entered in the channel, from the edges and the islands erosion, before steady, and in bigger degree, through the tributaries that drain the contribution basin area, modified for the use of the land (cattle and agriculture), the excess of sediments intensified the lateral sedimentation and the formation of bars of the central type, increasing the interlacement of the channel and, therefore, its morphology. It was estimated that between 1965 and 1998, about 233 million tons of sediments had been stored in the fluvial channel of Araguaia river. In the new sedimentation areas it was developed herbaceous vegetation adapted to the sandy surfaces. It was evident that it is occurring, in the plain, the substitution of a bigger vegetation, with bigger floristic diversity, for a grassy vegetation of the type herbaceous, associates to the formation of a geomorphologic unit younger and unstable to the erosive and sedimentary processes, because of the hydrologic channel behavior. This fact probably will bring consequences to the diverse biological processes associates to all alluvial plain. In one another approach, throughout the historical period of the analysis, was verified that as they increased the percentages of Cerrado natural vegetation areas in the area of the basin converted into agricultural areas and of cultivated pastures, the GDP of the cities also increased. The correlation between deforested areas, growth of the GDP, volume and mass of sediments stored in the fluvial system and increase of arenaceous bars in the channel resulted absolutely in satisfactory evidences in inferring that the economic growth of the region is in a relation of direct dependence with the changes in the use of the land of the Cerrado areas, and its ambient implications in the processes of morphologic changes in the Araguaia River channel and plain / A bacia do rio Araguaia é um dos sistemas fluviais mais importantes da América do Sul. Com uma área de 380.000 km2, inclui duas regiões fitogeográficas que concentram boa parte da biodiversidade do planeta: o Cerrado ao sul e Floresta Amazônica ao norte. O alto grau de destruição do bioma Cerrado e mudanças no uso da terra em larga escala, para a expansão das atividades agropecuárias, a partir de 1965, resultaram em um maior aporte de sedimentos no sistema fluvial. O estudo abrange o trecho médio do rio Araguaia localizado entre a cidade de Barra de Garças (MT) e a confluência do rio Cristalino com o rio Araguaia junto à Ilha do Bananal, correspondendo a 580 km de extensão. A abordagem multidisciplinar do estudo teve como objetivo, analisar os processos geomórficos do canal e da planície aluvial do médio rio Araguaia, que resultaram em mudanças ambientais para a morfologia do canal e consequentemente na dinâmica de sucessão vegetacional, desencadeadas por variáveis de transformação associadas aos processos erosivos e sedimentares no canal. Os dados quantitativos dos elementos morfológicos, processos erosivos e sedimentares do canal e da planície aluvial foram obtidos através de mapeamentos com o uso de cartas planialtimétricas, fotografias aéreas USAF (1965), imagens de satélite Landsat 1 MSS (1975) e Landsat 5 TM (1998). Utilizando os recursos de geoprocessamento, foram gerados relatórios areais das superfícies erodidas e sedimentadas e aplicadas equações matemáticas para estimar volume e massa dos sedimentos remobilizados e armazenados no sistema fluvial. Além dos dados geomorfológicos, foram obtidas informações socioeconômicas da área da bacia do Araguaia no Estado de Goiás, entre as décadas de 1960 e 2000, como o PIB (Produto Interno Bruto) dos municípios inseridos na bacia, estatísticas do crescimento do rebanho bovino e dados da área da cobertura vegetal de Cerrado e desmatamento. Interrelacioanando os dados físicos e socioeconômicos foi possível obter uma correlação entre o desencadeamento dos processos geomorfológicos que alteram o canal e o crescimento e desenvolvimento das atividades socioeconômicas. Os resultados revelaram que entre 1965 e 1975 poucas mudanças morfológicas ocorreram no canal fluvial. A partir de 1975, tem início um processo acelerado de erosão das margens do canal e de ilhas, remobilizando além dos sedimentos, a vegetação de maior porte, como as do tipo arbórea e arbustivo-arbórea, que estão associadas às unidades mais velhas da planície aluvial. Com um maior aporte de sedimentos que entraram no canal, a partir da erosão das margens e das ilhas, antes estáveis, e em maior grau, através dos afluentes que drenam a área de contribuição da bacia, alteradas pelo uso da terra (agricultura e pecuária), o excesso de sedimentos intensificou a sedimentação lateral e a formação de barras do tipo centrais, aumentando o entrelaçamento do canal e, portanto, sua morfologia. Estimouse que entre 1965 e 1998 cerca de 233 milhões de toneladas de sedimentos ficou armazenado no canal fluvial do rio Araguaia no trecho de estudo. Nas novas áreas de sedimentação, desenvolveu uma vegetação herbácea adaptada às superfícies arenosas. Ficou evidente que vem ocorrendo na planície a substituição de uma vegetação de maior porte, com maior diversidade florística, por uma vegetação de gramíneas do tipo herbáceas, associadas à formação de uma unidade geomorfológica mais jovem e instável, aos processos erosivos e sedimentares, devido ao comportamento hidrológico do canal. Este fato, provavelmente trará consequências a diversos processos biológicos associados à planície aluvial. Em outra abordagem, ao longo do período histórico da análise, verificou-se que à medida que aumentavam as porcentagens de áreas de vegetação natural de Cerrado convertidas em áreas agrícolas e de pastagens cultivadas, o PIB dos municípios apresentava crescimento. A correlação entre áreas desmatadas, crescimento do PIB, volume e massa de sedimentos armazenados no sistema fluvial e aumento de barras arenosas no canal resultaram em evidências absolutamente satisfatórias em inferir que o crescimento econômico da região encontra-se numa relação de dependência direta com as mudanças no uso da terra das áreas de Cerrado, e suas implicações ambientais nos processos de mudanças morfológicas no canal e na planície aluvial do rio Araguaia

The overall objective is to improve the one-dimensional numerical prediction of the fine and non-cohesive bed material load in alluvial rivers, especially during high intensity episodes during which sediment beds are strongly remobilized. For this reason, we attempt to reduce the major inaccuracy sources coming from the alluvial resistance and bed material load relations needed to close the mathematical system. Through a shared parameter called the control factor m, the interactions occurring in alluvial rivers are incorporated more deeply into the mathematical model and more particularly into the closure laws: bed material load (SVRD, Suction-Vortex Resuspension Dynamics) and the energy slope (Verbanck et al. 2007). The control factor m is assumedly related to the Rossiter resonance modes of the separated flow downstream the bed form crest. <p><p>To further improve the representation of the flow-sediment-morphology interactions, a fully coupled model approach has been naturally chosen. In this work the terminology fully coupled means that the three equations forming the system are solved synchronously and that the terms often neglected by more traditional decoupled models are kept. <p><p>The feasibility of the new closure methodology has been drawn up by reproducing numerically the silt-flushing experiment conducted by the Yellow River Conservancy Commission (Y.R.C.C.) in the Lower Yellow River (LYR) in Northern China. The objective of the silt flushing experiment is to reverse the aggradation trend of the Lower Yellow River which, in the last decades, has become a perched river. The numerical simulation specifically reproduces the silt-flush effects in a reach of LYR located in the meandering part of the river. This reach (around 100 km) is delimited by Aishan and Luokou hydrometric stations.<p><p>Since the SVRD formulation has been developed from flume observations, the law has first been confronted to river datasets. The confrontation has revealed that the SVRD law becomes less suitable for fine sediment fluxes (ratio of water depth over median particle size > 5000). Therefore, a modified equation SVRD-2 has been built to enlarge the validity range.<p><p>The suitability of the SVRD-2 equation to predict fine sediment fluxes has been tested on data available from several hydrometric stations located in the meandering reach of the LYR: historical observations and measures collected during the flushes. The SVRD-2 has also been compared with relations specifically calibrated for this configuration. The comparison has pointed out that the performance of the two formulas is similar, which is encouraging for the SVRD-2 approach as it has not been calibrated on those data. <p><p>The closed equation system has been written on its quasi-linear form and is solved by a Finite Volume Method combined with a linearized Riemann algorithm. The numerical model has been checked up on two test cases: deposition upstream of a dam and the aggradation experiment conducted by Soni 1975. <p><p>As it is not yet possible to predict dynamically the value of the control factor m, a possible solution would be to extract its value from the measured data at the inlet cross section. Unfortunately, the necessary data are not measured locally. Moreover, a uniform value of the control factor m may not suffice to reproduce the flow along the whole reach. Therefore, it has been proposed to work temporarily in the reverse way. <p><p>From the comparison between the numerical results and the experimental data, a time evolution of the control factor m has effectively been extracted and it has been shown that it varies along the reach. At Aishan, the evolution of the control factor m corresponds to the evolution expected from the data analysis previously conducted on other data sets: the value of the control factor m decreases during the flush as it tries to reach the optimal value m=1. The time evolution at Luokou behaves differently to the one at Aishan, but remains in agreement with m evolution patterns observed historically for the river section flowing round Jinan City walls. For Luokou, the highlighted differences may come from three dimensional effects coming from the meander bend upstream the station.<p><p>Generally, the results obtained for the hydraulics, the sediment transport and bed adaptation are encouraging but still need improvements and additional feeding from the experimental data. The results for the concentration and therefore the bed elevation are very sensitive to the value of the control factor m as it influences most of the terms of the bed material load equation (SVRD-2). <p><p>The major remaining difficulties are, firstly, to deal with the rapid transients for which the model is less suitable and, secondly, to improve the prediction of the value of control factor m. Before paying more attention into the transients, enhancements concerning the flow along the reach (initial condition and discharge rates during the first days of the flush) must be conducted in priority. Indeed as the prediction of the bed or the cross section evolutions depend directly on the quality of the prediction of the sediment concentration and the hydraulics, one should first improve these aspects. To perform this study, more information about the water levels or sediment concentrations is necessary at some intermediate stations. One solution is to lengthen the studied reach, upstream to Sunkou and downstream to Lijin, totaling a river length of 456 Km.<p><p>A more entire signal of the energy slopes and the associated bed configurations at different stations would enlighten how the control factor m evolves along the reach during the silt-flush events. <p><p> / Doctorat en Sciences de l'ingénieur / info:eu-repo/semantics/nonPublished

Direct mountain front recharge (MFR), water table recharge at the base of the mountain front, was evaluated on the arid (<250 mm/yr precipitation) Silver Island Mountains by comparing mountain precipitation to groundwater response. Direct MFR contributions were assessed on two catchments, one bedrock (i.e., mountain block) dominated and the other alluvial fan (i.e., mountain front) dominated. Catchment precipitation and shallow groundwater levels at each catchment outlet were measured for a 24 month period beginning October 2005. This time period captured one complete hydrologic cycle (December 2005-February 2007) for which annual and seasonal direct MFR rates were calculated. Annual direct MFR was calculated using a modified version of the water table fluctuation (WTF) method as 0.015-0.016% of precipitation on both catchments, with seasonal variations of 0% in summer up to 0.023% in winter, spring and fall. Seasonal direct MFR contributions are similar on the bedrock and the alluvial fan dominated catchments, with a notable exception during fall 2006 when direct MFR was twice as effective on the bedrock dominated system than on the alluvial fan dominated system (0.022% and 0.011% of precipitation, respectively). Darcy's law calculations show similarly low annual direct MFR contributions (0.013-0.032% of precipitation) as those calculated by the WTF method. Calculated direct MFR is 10% or less than typical calculated combined MFR (near surface recharge and deep underflow from the mountain block) for similar terrains and climates, and is only 3.5% of the combined MFR for the Silver Island Mountains as calculated by the Maxey-Eakin model. However, based on total recharge to the adjacent playa, it is apparent that the Maxey-Eakin model overestimates combined MFR, and the small calculated direct MFR is at least 50% of combined MFR. Despite some uncertainty in the numerical results, several patterns are evident in the data. The data show that direct MFR occurs in response to small rainfall events throughout much of the year, and that snowmelt is not necessary to produce direct MFR. The data also show that direct MFR responds more quickly and flushes through the system faster on the alluvial fan catchment than on the bedrock catchment.

The late Middle Jurassic (Callovian) Entrada Sandstone has been divided into two general facies associations consisting primarily of eolian sandstones in eastern Utah and "muddy" redbeds in central Utah. Sedimentary structures within the redbed portion are explained by the interfingering of inland sabkha, alluvial, and eolian depositional systems. A complete succession from the most basinward facies to the most terrestrial facies in the Entrada Sandstone consists of inland sabkha facies overlain by either alluvial or eolian facies. Where both alluvial and eolian facies interfinger, alluvial facies overlain by eolian facies is considered a normal succession. Sequence boundaries, often identified by more basinward facies overlying more landward facies, are observed in the Entrada Sandstone and are extrapolated for the first time across much of Utah, including both the eolian-dominated and redbed-dominated areas. Using these sequence boundaries as well as recent tephrochronologic studies, three time correlative surfaces have been identified in the Entrada. Based on the facies interpretations at each surface, five paleogeographic reconstructions and five isopach maps have been created, illustrating two major intervals of erg expansion and the location of the Jurassic retroarc foreland basin's potential forebulge. Eolian (erg-margin) sandstones pinch-out into muddy redbeds creating combination traps, as evidenced by dead oil (tar) and bleached eolian sandstone bodies within the Entrada. The Entrada Sandstone is a world-class analog for similar systems, such as the Gulf of Mexico's Norphlet Sandstone, where eolian facies grade into muddy redbed facies.