Made available in DSpace on 2016-08-19T17:47:12Z (GMT). No. of bitstreams: 1 LUIS ALFREDO LOPES SOARES.pdf: 9086971 bytes, checksum: 8228f0b447540ace59bc3dd69d26d6f0 (MD5) Previous issue date: 2004-04-26 / The salinization vulnerability of groundwater in the Itaquí-Bacanga area, caused by the super exploitation in the coastal aquifers usually creates the phenomenon of seawater intrusion, justified by the increasing of the freshwater/ seawater interface, which can bring a scenario of general contamination. Instead of using traditional methods for contamination evaluation, which are not applicable in this case, different methods must be applied using much more complex knowledges about hydrogeology and hydrochemistry that demand more tools for collecting hydrogeochemistry parameters. In the northwest coast of the island of São Luís, Itaquí-Bacanga area, some zones in the aquifer system are already seriously damaged by reasons explained above, causing deactivation of some wells through salinization. From the analysis of lithologic profiles, physicochemical parameters and integrating geotopographics and chemical datas, a vulnerability map was built, also considering historical features. / A vulnerabilidade à salinização das águas subterrâneas na área Itaquí Bacanga, consequência da super explotação de aquíferos costeiros provoca, em geral, o fenômeno de intrusão salina, decorrente do avanço da interface água doce/água salgada, podendo ocorrer uma situação de contaminação generalizada. O uso de metodologias tradicionais para avaliação de contaminação não se aplica a esta situação. Em consequência, utiliza-se metodologia distinta e bem mais complexa, envolvendo conhecimentos de hidrogeologia e hidroquímica, que necessitam de numerosas ferramentas para a obtenção de parâmetros hidrogeoquímicos. Na costa noroeste da ilha de São Luís, na área Itaquí Bacanga, o sistema aquífero encontra-se, em alguns setores, gravemente afetado por este fenômeno, já tendo ocorrido desativação de poços salinizados. A partir da análise de perfis litológicos, análises físico-químicas e de seções integrando dados geotopográficos e químicos, foi gerado um mapa de vulnerabilidade que considerou também situações históricas.

Variable groundwater quality in complex aquifer-aquitard systems presents a challenge for sustainable groundwater development. In the Lower Murrumbidgee alluvial fan of the Murray-Darling Basin in semi arid inland Australia, shallow groundwater is saline (12000 &micro S/cm) and locally contaminated by nitrate. Deep fresh aquifers (150 &micro S/cm), developed as an irrigation water supply, were thought to be protected from downwards leakage by laterally extensive aquitards. However, hydrochemical sampling, augmented by historic data, revealed that aquifer salinisation (400 to 4000 &micro S/cm) had occurred at some sites to 50 m depth since the mid 1980s. Aquitard windows, landscape depositional features at a scale of 10s to 100s of metres which are rarely detected by conventional investigations, were proposed as conduits for rapid downwards leakage in stressed systems. Intensive research was conducted at the Tubbo site where downhole geophysical logging and minimally disturbed cores were used to describe a saline clayey silt to 15m depth, an indurated clayey sand and 2 deep deposits of hard clayey silt. Fracturing was inferred by the scale dependency of aquitard permeability (Kv 10E-11 to 10E-6 m/s). Lithological variation near the surface was delineated by electrical imaging which revealed a 40m wide aquitard window beneath a veneer of smectite clay. Intensive monitoring of groundwater pressures in six piezometers (23-96 m depth) near the Tubbo irrigation bore and two other peizometers upgradient, indicated that the indurated clayey sand formed an effective hydraulic barrier but the deep silty deposits were spatially discontinuous. Groundwater samples were collected before, three times during, and after the 1998-99 irrigation season. A large, but delayed TDS increase occurred in the shallow aquifer and small pulses of saline water were sustained in the middle aquifer but shortlived in the deep aquifer. Hydrochemical and isotopic data dC-13, dH-2, dO-18, C-14 and H-3) showed the middle aquifer mixing with the deep aquifer, though retaining the signature of a palaeowater. Hydrochemical changes were accounted for with PHREEQC inverse mass balance models for the shallow aquifer. Mixing of aquifer water with 20-70% saline porewater from the upper aquitard occurred, together with ion exchange and NaCl dissolution. Based on an axisymmetric radial FEFLOW model, 5-30% of the volume pumped was accounted for by vertical leakage from the middle aquifer. Leakage from the shallow aquifer was small but significant, as it allowed high salinity water to migrate. Permeability and compressible storage measurements (Ss 10E-5 to 10E-4 /m) were used to constrain model calibration, and to show that direct mixing occurred mainly via aquitard windows at depth, and between the shallow and middle aquifers via leaky boreholes. Fracture flow and aquifer-aquitard interaction by diffusion were of secondary importance.

The master thesis deals with influence of system of water reservois and farming on suface water quality in catchment Košín stream in the Tabor region. There were investigated effect on suface water quality of several watercourses flowing through farmland with markedly different land cover, farming, size of catchment area and different water reservoirs. The fundamental hydrochemical parameters such as content of nutrient, inorganic and organic carbon and undissolved substances were monitored. The water samples were collected from permanent sampling points during the growing season. The investigated compounds were determined in the laboratory by titration, gravimetry and spectrophotometry. Mean, median, interquartile range were determined within the basic descriptive statistics and the data were statistically processed by nonparametric tests. Results showed particularly significant influence of the littoral vegetation and wide strips of tree vegetation as an effective filter, which prevent pollution of surface water by nutrient runoff. In some cases, the land cover was reflected positive impact of vegetation on reducing contamination of the water above the level specified by legislation, therefore vegetation is great importance in the fight pollution of waterways. From the obtained data it is obvious that influence of anthropogenic pollution on surface water is very important, but appropriate land cover can minimalize this impact.

Ziel der Arbeit ist es, ein genaueres Prozessverständnis zur Abflussbildung an Hängen auf der Basis der räumlichen Verbreitung periglazialer Deckschichten zu erhalten. Das Untersuchungsgebiet ist ein 6 ha großes, forstlich bewirtschaftetes Quelleinzugsgebiet im Osterzgebirge. Das anstehende Gestein ist Gneis. Der oberflächennahe Untergrund ist aus zwei- und dreigliedrigen Deckschichten zusammengesetzt. Auf der Punkt-, Hang- und Kleineinzugsgebietsskala werden hydrometrische, hydrochemische und geoelektrische Methoden sowie Färbeversuche eingesetzt, um auf die dominierenden Abflussbildungsprozesse schließen zu können. Aus der Synthese der Teilergebnisse werden drei typische Prozessabläufe in Abhängigkeit von der Gebietsvorfeuchte abgeleitet. Diese verdeutlichen, dass bei geringer Vorfeuchte Sättigungsoberflächenabfluss im Quellsumpf vorherrscht, bei mittlerer bis hoher Vorfeuchte dagegen Zwischenabfluss der dominierende Abflussprozess ist. Die Abflusswirksamkeit der Niederschläge steigt zudem mit zunehmender Vorfeuchte nichtlinear an. Es wird herausgestellt, dass die hydraulisch anisotropen Eigenschaften der Basislage entscheidend die oberflächennahen Fließwege des Wassers beeinflussen. Sie besitzt durch ihre hohe Lagerungsdichte einerseits vertikal wasserstauende Eigenschaften. Andererseits kann Wasser, begünstigt durch das dominant sandige Substrat und das hangparallel eingeregelte Bodenskelett innerhalb der Schicht bevorzugt lateral geleitet werden. Die gewonnenen Erkenntnisse verdeutlichen die Bedeutung der Eigenschaften der periglazialen Deckschichten für die Abflussbildung an Mittelgebirgshängen. / The aim of this study is to contribute to the understanding of runoff processes on slopes based on the spatial distribution of periglacial cover beds. The study area is a 6 ha large forested spring catchment in the Eastern Ore Mountains, Saxony. Bedrock is gneiss overlain by periglacial cover beds comprising two or three layers. On plot, hillslope and small-catchment scales hydrometrical, hydrochemical and geoelectrical methods as well as tracer experiments are used to determine the constitutive runoff processes. From the synthesis of partial results, three pre-moisture controlled process cycles are derived. With low pre-moisture, saturation overland flow dominates in the spring bog. In contrast, with medium or high pre-moisture interflow occurs. Besides, with rising pre-moisture runoff coefficients increase in a non-linear manner. It is emphasised that the hydraulic anisotropic structure of the Basal Layer is the major control factor for subsurface water-flow paths. On the one hand, this layer acts as an aquitard for seeping water because of its high bulk density. On the other hand, water within the layer is able to flow laterally because of the sandy texture and the coarse clasts oriented parallel to the slope. These findings highlight the importance of relic periglacial cover beds for runoff generation in subdued mountains.

Ziel der Arbeit ist es, ein genaueres Prozessverständnis zur Abflussbildung an Hängen auf der Basis der räumlichen Verbreitung periglazialer Deckschichten zu erhalten. Das Untersuchungsgebiet ist ein 6 ha großes, forstlich bewirtschaftetes Quelleinzugsgebiet im Osterzgebirge. Das anstehende Gestein ist Gneis. Der oberflächennahe Untergrund ist aus zwei- und dreigliedrigen Deckschichten zusammengesetzt. Auf der Punkt-, Hang- und Kleineinzugsgebietsskala werden hydrometrische, hydrochemische und geoelektrische Methoden sowie Färbeversuche eingesetzt, um auf die dominierenden Abflussbildungsprozesse schließen zu können. Aus der Synthese der Teilergebnisse werden drei typische Prozessabläufe in Abhängigkeit von der Gebietsvorfeuchte abgeleitet. Diese verdeutlichen, dass bei geringer Vorfeuchte Sättigungsoberflächenabfluss im Quellsumpf vorherrscht, bei mittlerer bis hoher Vorfeuchte dagegen Zwischenabfluss der dominierende Abflussprozess ist. Die Abflusswirksamkeit der Niederschläge steigt zudem mit zunehmender Vorfeuchte nichtlinear an. Es wird herausgestellt, dass die hydraulisch anisotropen Eigenschaften der Basislage entscheidend die oberflächennahen Fließwege des Wassers beeinflussen. Sie besitzt durch ihre hohe Lagerungsdichte einerseits vertikal wasserstauende Eigenschaften. Andererseits kann Wasser, begünstigt durch das dominant sandige Substrat und das hangparallel eingeregelte Bodenskelett innerhalb der Schicht bevorzugt lateral geleitet werden. Die gewonnenen Erkenntnisse verdeutlichen die Bedeutung der Eigenschaften der periglazialen Deckschichten für die Abflussbildung an Mittelgebirgshängen. / The aim of this study is to contribute to the understanding of runoff processes on slopes based on the spatial distribution of periglacial cover beds. The study area is a 6 ha large forested spring catchment in the Eastern Ore Mountains, Saxony. Bedrock is gneiss overlain by periglacial cover beds comprising two or three layers. On plot, hillslope and small-catchment scales hydrometrical, hydrochemical and geoelectrical methods as well as tracer experiments are used to determine the constitutive runoff processes. From the synthesis of partial results, three pre-moisture controlled process cycles are derived. With low pre-moisture, saturation overland flow dominates in the spring bog. In contrast, with medium or high pre-moisture interflow occurs. Besides, with rising pre-moisture runoff coefficients increase in a non-linear manner. It is emphasised that the hydraulic anisotropic structure of the Basal Layer is the major control factor for subsurface water-flow paths. On the one hand, this layer acts as an aquitard for seeping water because of its high bulk density. On the other hand, water within the layer is able to flow laterally because of the sandy texture and the coarse clasts oriented parallel to the slope. These findings highlight the importance of relic periglacial cover beds for runoff generation in subdued mountains.

Στην περιοχή του ΒΔ Λασιθίου απαντώνται οι γεωλογικοί σχηματισμοί των πλακώδων ασβεστόλιθων και των ασβεστόλιθων της ζώνης Τρίπολης. οι σχηματισμοί αυτοί είναι έντονα καρστικοποιημένοι και αποτελούν τους κύριους υδροφόρους της περιοχής έρευνας. Μεταξύ των δύο υδροφόρων, στις περιοχές Νεάπολης και Ποτάμων παρεμβάλλονται τα αδιαπέρατα στρώματα των Φυλλιτών-Χαλαζιτών. Ο υδροφόρος που αναπτύσσεται στους ανθρακικούς σχηματισμούς της ζώνης Τρίπολης κατηγοριοποιείται σε τρεις ζώνες σύμφωνα με τον υδροχημικό χαρακτήρα του υπόγειου νερού. η πρώτη ζώνη αποτελείται από τις περιοχές τροφοδοσίας του υδροφόρου (Δράσι, Άγιος Κωνσταντίνος και Ποτάμοι) με εξαίρετη ποιότητα νερού, η δεύτερη ζώνη συνιστάται από τις περιοχές των Λακωνίων και Κριτσάς, όπου το νερό του υδροφόρου έχει επηρεαστεί από τη διείσδυση του θαλασσινού νερού. Τέλος, η τρίτη ζώνη αποτελείται από τις παράκτιες περιοχές του Αγίου Νικολάου και Αλμυρού με έντονη επιρροή από την διαδικασία της υφαλμύρινσης Ο υδροφόρος που αναπτύσσεται στους Πλακώδεις ασβεστόλιθους είναι ανοικτός στην θάλασσα και επηρεάζεται στο σύνολο του από την διείσδυση του θαλασσινού νερού. Με τη χρήση των κανονικοποιημένων διαγραμμάτων των σπάνιων γαιών, τόσο σε δείγματα πετρωμάτων όσο και σε δείγματα νερού προέκυψε ότι οι δύο καρστικοί υδροφόροι επικοινωνούν υδραυλικά στην περιοχή του Δάμακα Β-ΒΔ του Αγίου Νικολάου. / The region of NW Lasithi is dominated by plattenkalk and Tripoli’s zone limestones. These geological formations are characterized by karst and host the main aquifers of study area. Impermeable layers of phyllite-quartzite formation occur between these limestone formations, in the areas of Neapolis and Potami. The aquifer hosted by the carbonate formations of Tripoli’s zone is divided in three zones based on the hydrochemical characteristics of the underground water. The first zone includes the areas Drasi, Agios Konstantinos and Potami that are the sources of the aquifer, with excellent water quality. The second zone consists of the areas Lakonia and Kritsa, in which the underground water have been infiltrated by sea water. Finally the third consists of the coastal zones of Agios Nikolaos and Almyros, which have been affected by the process of brackish water. The aquifer hosted by the plattenkalk limestones is open to the sea and is affected by the intrusion of sea water. It can be shown, using normalized rare earth element diagrams of analyses of both rocks and underground waters, that the two karstified aquifers communicate hydraulically in the area of Damakas, N-NW of city Agios Nikolaos.

La présente étude est une contribution à la connaissance de la géochimie des eaux de la partie inférieure du bassin versant de la rivière N’djili située à l’Est de Kinshasa (République Démocratique du Congo). Les eaux de surface ont été échantillonnées sur six sites de prélèvements au cours de la période allant d’avril 2005 à février 2006, deux sites supplémentaires ont été ajoutés sur le fleuve Congo à partir de 2007. Onze campagnes d’échantillonnages ont permis un suivi annuel (avril 2005 à février 2006), trois autres ont eu lieu de mai à juillet 2007 et vingt-deux autres d’octobre 2008 à octobre 2009. Les paramètres physico-chimiques suivants ont été mesurés :température, pH, conductivité, alcalinité, oxygène dissous. Les dosages des éléments majeurs (anioniques et cationiques) et de certains éléments traces ont été effectués pour étayer cette étude géochimique. <p><p>Il ressort de cette étude que la température de l’eau prélevée est proche de la température moyenne atmosphérique dans la zone d’étude, ce qui indique un équilibre thermique entre les eaux de surface et l’atmosphère.<p><p>Dans certains cas, les valeurs de pH mesurées peuvent être très basses à cause du lessivage des acides organiques provenant de la végétation en décomposition et de la présence d’anhydride carbonique dissous (Burler et Ison, 1966). A la vue des résultats d’analyse des eaux de pluies, nous pouvons remarquer que l’acidité des eaux prélevées de cette partie du bassin versant serait en partie due à la contribution des précipitations.<p><p>Pour ce qui est de la conductivité, à l’exception du site Matete, les valeurs mesurées sont inférieures à 100 µS/cm, ce qui correspond aux eaux de surface très faiblement minéralisées. Il n’y a pas beaucoup de variation de conductivité entre la saison des pluies, période des hautes eaux, et la saison sèche, période des basses eaux. Ceci nous montre à nouveau qu’il y a une contribution importante des précipitations dans la composition des eaux échantillonnées puisqu’il n’y a pas de grand écart de valeur en l’absence de précipitation.<p><p>La solubilité de l’oxygène dans l’eau diminue lorsque la température augmente, ce qui induit une diminution de la concentration en oxygène à saturation. Le calcul du taux de saturation dans nos échantillons montre que les eaux sont sous-saturées en oxygène. Ceci peut s’expliquer par le fait que ce bassin versant, du moins dans la zone d’étude, subit des rejets d’eaux usées et des rejets de l’usine de traitement des eaux (REGIDESO). Nous soupçonnons la présence d’une pollution organique induisant la consommation de l’oxygène dissous par respiration. <p>Les teneurs des éléments ne sont pas constantes au cours du temps. Certains sont plus abondants que d’autres (en particulier HCO3-, Ca+, Na+, K+, SiO2 et Cl-). Il n’y a pas de variations saisonnières importantes des éléments majeurs. L’ordre d’abondance décroissant pour les cations est Na+>Ca2+>K+>Mg2+ et pour les anions est HCO3->Cl-≈NO3->SO42-.<p><p>La corrélation entre la conductivité électrique et les teneurs en composés chimiques majeurs montre que la conductivité est surtout contrôlée par les bicarbonates, les nitrates, les chlorures, les sulfates, le sodium, le magnésium, le calcium et le potassium. Ces eaux sont particulièrement peu chargées en éléments minéraux dissous, la moyenne des TDS (Total Dissolved Salts) pour chaque site étant largement inférieure à la moyenne mondiale des eaux de rivière, qui est 100 mg/l (Berner et Berner, 1987), tendance également observée pour le calcium (5,7 mg/l pour les rivières africaines et 13,4 mg/l pour la moyenne mondiale). Seul le site de Matete présente une moyenne supérieure à ces valeurs. Pour la silice dissoute, par contre, les concentrations observées sont voisines de la moyenne mondiale (10,4 mg/l).<p><p>Les valeurs du bilan ionique sont en majorité négatives, c’est-à-dire qu’elles traduisent un excès d’anions. Le calcul du bilan ionique a été effectué pour chaque point de prélèvements, pour les deux dernières séries de campagnes de prélèvements, soit de mai à juillet 2007 et d’octobre 2008 à octobre 2009.<p><p>Cette étude nous a permis de dégager des groupes au comportement commun qui reflètent des faciès géochimiques différents et dont les plus importants sont les suivants :(1) Le faciès bicarbonaté calcique :il correspond aux eaux provenant des écoulements sur des roches hypersiliceuses (grès, quartzites). Le magnésium est le deuxième cation dominant après le calcium pour le site de prélèvements CFAM (Confluence Fleuve Amont) représentant plus de 20% de la teneur en cations. Et, (2) Le faciès bicarbonaté sodique :il correspond au point de prélèvement Kwambila qui, bien que situé sur une roche hypersiliceuse, présente le sodium comme cation dominant et les nitrates comme anions dominants après les bicarbonates. Ce point de prélèvement est caractérisé par une activité agricole induisant l’utilisation de fertilisants azotés. L’élevage porcin est également pratiqué dans cette région. Ces activités humaines pourraient expliquer la prédominance du sodium et du nitrate dans cette région pour toutes les saisons confondues. <p> <p>SUMMARY<p>The present study contributes to a better understanding of the water<p>geochemistry in the N’djili river catchment, East from Kinshasa (Democratic<p>Republic of Congo). Surface waters have been collected at six sampling sites during the period from April 2005 and February 2006. Two additional sampling sites have been added since 2007. Eleven sampling campaigns allowed an annual<p>follow-up (April 2005 to February 2006), three others took place from May to<p>July 2007 and twenty-two additional ones from October 2008 to October 2009.<p>The physico-chemical parameters that have been measured are as follows:<p>temperature, pH, conductivity, alkalinity, dissolved oxygen. The measurement of<p>major elements (anions and cations) and some trace elements has been<p>performed in order to support this geochemical investigation.<p>The temperature of the riverine waters appears to be close to the mean air<p>temperature in the study area, indicating a thermal equilibrium between surface<p>waters and the atmosphere.<p>In some cases, values pH measured can be very low due to the leaching of<p>organic acids originating from both decomposing vegetation and the presence of<p>dissolved carbon dioxide (Burler and Ison, 1966). Based on the analyses of the<p>rain waters, one can note that the acidity of riverine waters results partially from<p>the atmospheric precipitation.<p>Regarding conductivity, with the exception of Matete area, the values are below<p>100 μS/cm, which corresponds to weakly mineralized surface waters. Little<p>variation in conductivity was observed between rainy and dry seasons is low,<p>suggesting again an important control of the riverine water composition by the<p>precipitation.<p>Oxygen solubility in the riverine waters decreases with increasing temperature,<p>which results in a decrease of dissolved oxygen content. The calculation of the<p>saturation state in our samples show that the riverine waters are undersaturated<p>with oxygen. This phenomenon can be explained by the fact that the river<p>catchment, at least for the study area, is subjected to untreated and treated<p>sewage effluent releases. One may expect an organic pollution leading to a<p>consumption of dissolved oxygen by respiration.<p>The concentrations of dissolved elements are variable with time. Some are more<p>abundant than others (especially HCO3-, Ca+, Na+, K+, SiO2 and Cl-). There is no<p>major seasonal variability for the major dissolved elements. The abundance<p>decreases in the orders Na+>Ca2+>K+>Mg2+ and HCO3->Cl-≈NO3->SO42- for<p>cations and anions, respectively.<p>Correlation between conductivity and major element concentrations show that<p>the former is mainly dictated by bicarbonates, nitrates, chlorides, sulfates,<p>sodium, magnesium, calcium and potassium. These riverine waters are<p>particularly low in dissolved minerals, the mean TDS (Total Dissolved Salts) for<p>each site being largely lower than the global average for rivers (i.e. 100 mg/l,<p>Berner and Berner, 1987). Calcium displays the same trend, with 5.7 mg/l for<p>African rivers in comparison with a global average of 13.4 mg/l. Only Matete area<p>exhibits a mean higher than these values. For dissolved silica, however, the<p>measured contents are close to the global average (i.e. 10.4 mg/l).<p>The values of the ionic balance are negative most of the time, suggesting an<p>excess in anions. The calculation of the charge balance has been realised for<p>each sampling location, during the two last campaigns (i.e. May 2007 - July 2007<p>and October 2008 – October 2009).<p>This study sheds some light on the groups of elements exhibiting a common<p>behaviour but reflecting different geochemical facies. The most important ones<p>are the following: (1) calcium bicarbonate facies: it corresponds to the water<p>run-off from silicate rocks (sandstone, quartzite). Magnesium is the second<p>dominant cation (after calcium) for the CFAM (“Confluence Fleuve Amont”)<p>sampling site, accounting for more than 20% of cation load. And (2) sodium<p>bicarbonate facies: it corresponds to the Kwambila sampling site, where sodium<p>is present as dominant cation and nitrates as dominant anion (after<p>bicarbonates). This sampling site is characterized by agricultural activities<p>entailing the use of nitrogen-rich fertilizers. Pig farming is also practiced in this<p>region. Theses human activities could therefore explain the predominance of<p>both sodium and nitrate in this area, irrespective of the season.<p> / Doctorat en Sciences / info:eu-repo/semantics/nonPublished