Made available in DSpace on 2015-09-25T12:23:38Z (GMT). No. of bitstreams: 1 Ronaldo Justino de Araujo Junior.pdf: 1045639 bytes, checksum: 74c1ae9be07d1e1244c7e92e41b32bb8 (MD5) Previous issue date: 2009-09-17 / The eutrophication process on water bodies, resulting of anthropogenic activities, is one of more serious problems of degradation of water quality, limiting its use for various purposes. The evaluation of trophic state has produced satisfactory results for the management of water resources. This study aimed to study the water quality of Epitácio Pessoa dam PB, between the years 1989 to 2008 and assess the trend of the evolution of trophic levels. The information in this study were from the database of the Laboratory of Aquatic Ecology LAE of Paraíba State University on the period 2005 to 2008 and Ph.D. theses developed between 1989 and 2003. The water temperature ranged between 23.6 C and 29.6 º C, with higher values between 2003 and 2008. The average pH ranged between 7.4 and 9.11 higher in the dry season. The electrical conductivity was highest between 2002 and 2003 (525μS/cm the 633μS/cm), when the volume stored in the reservoir was reduced to 35.4% of capacity. The highest concentrations of dissolved oxygen occurred between 1989 and 1991 (average > 8.0 mg / L). The average concentrations of ammonia were higher between 1991 and 2003, during which the dam had less volume of water. Nitrates were higher between 1989 and 2003, decreased between 2005 and 2006 resulting in the delivery of large volumes of water. The total phosphorus ranged from 4 μg/L and 125 μg/L, higher between 1991 and 2003. Between 1989 and 1991 chlorophyll "a" had the highest values in the rainy season, between 3.3 μg/l and 6.7 μg/l. From the rain 3 (2002), the highest concentrations occurred in the dry season. The Epitácio Pessoa dam was classified as oligo-mesotrophic (1989 - 1991), mesotrophic (2002 - 2003), oligotrophic (2005 - 2007) and oligo-mesotrophic (2008), showing a higher trophic gradient in the period of greatest reduction in volume, reflecting the increased concentrations of nutrients. The variables that correlated with changes in STI-average, were the total phosphorus, soluble orthophosphate and transparency. The information generated in this study could support future action planning and management of the waters of the Epitácio Pessoa dam, a major source of drinking water in the state of Paraíba. / O processo de eutrofização nos corpos aquáticos, resultante das atividades antropogênicas, constitui um dos problemas mais graves de degradação da qualidade da água, limitando seu uso para diversos fins. A avaliação do estado trófico tem produzido resultados satisfatórios para o manejo dos recursos hídricos. Esse estudo teve como objetivos estudar a qualidade da água do açude Epitácio Pessoa - PB entre os anos de 1989 a 2008 e avaliar a tendência da evolução dos níveis tróficos. As informações desse estudo foram provenientes da base de dados do Laboratório de Ecologia Aquática LEAq da Universidade Estadual da Paraíba no período de 2005 a 2008 e de teses de doutorado desenvolvidas entre 1989 e 2003. A temperatura da água variou entre 23,6ºC e 29,6ºC, com maiores valores entre 2003 e 2008. O pH médio variou entre 7,4 e 9,11 mais elevado na estiagem. A Condutividade Elétrica esteve mais alta entre 2002 e 2003 (525μS/cm a 633μS/cm), quando o volume armazenado no açude foi reduzido a 35,4% da capacidade. As maiores concentrações de oxigênio dissolvido, ocorreram entre 1989 e 1991 (médias > 8,0mg/L). As concentrações médias de nitrogênio amoniacal foram mais elevadas entre 1991 e 2003, período em que o açude contava com menor volume de água. Os nitratos foram mais elevados entre 1989 e 2003, com diminuição entre 2005 e 2006 resultante do aporte de grande volume de água. O fósforo total variou entre 4 μg/L e 125 μg/L, mais elevado entre 1991 e 2003. Entre 1989 e 1991 a clorofila a apresentou os maiores valores médios nas épocas chuvosas, entre 3,3 μg/l e 6,7 μg/l. A partir da chuva 3 (2002), as maiores concentrações ocorreram na estiagem. O açude Epitácio Pessoa classificou-se como oligo-mesotrófico (1989 1991), mesotrófico (2002 2003), oligotrófico (2005 2007) e oligo-mesotrófico (2008), evidenciando um maior gradiente trófico no período de maior redução do volume, repercutindo no aumento das concentrações dos nutrientes. As variáveis que melhor correlacionaram-se com as variações do IET-Médio, foram o fósforo total, o ortofosfato solúvel e a transparência. As informações geradas nesse estudo poderão subsidiar ações futuras de planejamento e gerenciamento das águas do açude Epitácio Pessoa, importante fonte de água para consumo humano no Estado da Paraíba.

Le bassin hydrographique de la Seine figure parmi les bassins français les plus anthropisés. Les communautés piscicoles qui le peuplent sont potentiellement marquées par les pressions humaines qui s'exercent sur le milieu aquatique, et dont l'ampleur depuis l'Époque industrielle a été grandissante. L'objectif de ce travail était d'identifier les facteurs à l'origine des modifications de la répartition des peuplements de poissons sur le temps long. Afin de mettre en évidence les possibles changements intervenus durant les deux derniers siècles, ce travail a été mené en croisant deux types d'approches, l'une historique et l'autre écologique. Cette étude, basée sur des données d'observations de poissons dans le bassin de la Seine depuis le début du XIXe siècle, montre une importante modification de la faune piscicole (i.e. introductions et disparitions d'espèces) à l'échelle du bassin. Par ailleurs. L’analyse comparative des données historiques, pour lesquelles existent des mentions d'abondances, et des données écologiques actuelles montre que les aires de répartition de certaines espèces ont été très largement modifiées. Sur différents secteurs du bassin, les résultats témoignent d'évolutions parfois importantes de la composition des peuplements en lien avec différents types de pressions anthropiques exercées sur le milieu à des échelles d'espace et de temps variées. Ce travail confirme l'intérêt d'une approche interdisciplinaire dans la compréhension de l'histoire des écosystèmes. De futures recherches sont néanmoins nécessaires afin de cerner l'importance de facteurs plus locaux sur la répartition des espèces piscicoles. / In France, the Seine River basin has been harshly impacted by anthropogenic pressures since the Industrial revolution. Fish community is expected to be disturbed by these human pressures on aquatic environment. This thesis aimed to highlight the factors involved in the changes of fish species spatial distribution over the last two centuries using both historical and ecological approaches. The analysis of historical data of fish distributions on the Seine River basin showed some important modifications of fish communities (i.e. species introductions and extinctions) at the catchment scale, since the beginning of the XIXth century. The comparative study based on historical abundances and actual data showed that certain species have changed their distribution area. Besides, substantial evolutions in fish assemblages occurred in certain rivers, probably in relation to anthropogenic pressures acting at different spatial and temporal scales. This study confirms the interest of an interdisciplinary approach to improve knowledge of ecosystems' history. Nevertheless, future researches are still needed to better understand the effects of local factors on fish distribution area.

Esta pesquisa estuda a evolução temporal dos parâmetros de propagação acústica de uma mistura de líquidos imiscíveis considerada como emulsão instável durante o processo de separação de suas fases. O principal objetivo neste trabalho é estudar o comportamento não linear de materiais que variam sua não homogeneidade quando são submetidos a um campo acústico. O estudo é baseado na teoria de análise espectral de ecos de ultra-som para entender o processo físico de interação da onda - emulsão. A emulsão bifásica que tem sido analisada neste estudo é composta principlamente por um óleo mineral A e um óleo vegetal B. A metodologia é baseada na análise tempo freqüência de ecos e sinais de backscattering de ultra-som com uma freqüência central de 5 MHz e uma largura de banda de 8 MHz @ - 3dB. A velocidade média de propagação acústica para a mistura liquida foi estimada em 1354 m/s. O coeficiente de atenuação foi calculado para cada fase separada e se obtiveram os seguintes resultados: 0.82 dB/cm - MHz para o óleo A e 0.59 dB/cm - MHz para o óleo B. O parâmetro B/A avaliado para cada fase separada foi de: 8.43 para óleo A e 10.74 para o óleo B. A variação dos parâmetros acústicos descreveram a evolução da emulsão no tempo mediante o decremento das curvas de atenuação, B/A e IBC. A velocidade de propagação não forneceu informações relevantes a respeito do processo de separação das fases, devido a sua variação mínima. A percentagem média de variação dos parâmetros acústicos durante o processo dinâmico de separação das fases da emulsão foi de 1.39% para a velocidade de propagação, 46.9 para B e 51% para B/A. Espera-se que o estudo possa ser extrapolado para o melhor entendimento da interação de ondas de ultra-som em meios não homogêneos e variantes no tempo. / This research studies the time evolution of acoustic propagation parameters of a mixture of inmiscible liquids considerated as unstable emulsion during the separation process into its original phases. The main aspect of this work is to deal with the behavior of nonlinear, nonhomogeneous and time-varying media when they are submitted in an acoustic field. The study is based on spectral analysis theory of ultrasound-backscattered echoes for understanding of physical process of the wave-emulsion interaction. The biphasic emulsion, which has been analyzed during this study, is composed by a mineral oil (phase A) and vegetable oil (phase B). The methodology was based on time-frequency analysis of backscattered broadband ultrasound echo at center frequency of 5 MHz and bandwidth of 8 MHz @ -3dB using an ultrasound system in pulse-echo mode. The mean acoustic propagation velocity for the mixture liquid was estimated in 1354 m/s. The attenuation coefficients were calculated for each separated phase resulting in 0.82 dB/cm-MHz to phase A and 0.59 dB/cm-MHz to phase B. The B/A parameter have been evaluated resulting in 8.43 (phase A) and 10.74 (phase B). The acoustic parameters variation allowed identified different emulsification state inside emulsion. The time evolution for the emulsion was described throught the decrease of attenuation, B/A and IBC. The acoustic propagation velocity don\'t provide relevant information about the phases separation process, because it showed a minimal variation. The mean percentage variation for the time evolution of the acoustic parameters was 1.39% to the acoustic propagation velocity, 46.9% to B and 51% to B/A. We hope that observations can be extrapolated aiming a better understanding of ultrasonic waves interaction in non-homogeneous time-varying medium.

No description available.

Le paysage des rivières en tresses est constitué d’une riche mosaïque d’habitats diversifiés, déterminée par un ensemble de facteurs biophysiques qui interagissent à différentes échelles spatiales et temporelles.A partir d’une sélection de 53 tronçons en tresses, nous avons réalisé une analyse comparative à l’échelle régionale du bassin du Rhône et en fonction de plusieurs échelles temporelles, en mobilisant les techniques de télédétection.Premièrement, nous avons étudié la variabilité de la structure des habitats aquatiques et du patron des chenaux. Nous montrons que le patron de tressage et des habitats aquatiques n’est pas uniquement lié au débit, mais aussi aux conditions locales liées aux apports sédimentaires et à la présence de la nappe phréatique.Deuxièmement, nous avons abordé une approche diachronique afin de comprendre l’évolution à moyen terme du paysage fluvial de ces tronçons, depuis la moitié du siècle dernier. Les résultats montrent que toutes les tresses du bassin rhodanien ne sont pas déliquescentes et que certains tronçons sont encore très actifs. Cela dépend d’un ensemble de facteurs : la position géographique du tronçon, son évolution à court terme liée aux épisodes de crues et l’histoire des conditions anthropiques environnantes.Enfin nous avons analysé les trajectoires évolutives suivies par un sous-ensemble de 12 sites, analysés à une échelle temporelle plus fine (5 observations par site sur 50 ans). Nous observons que les tronçons suivent des trajectoires différentes, en fonction des conditions hydrologiques observables à un moment donnée (ex. crues), de la position géographique du tronçon et du contexte anthropique. De plus, certaines conditions locales (topographie et humidité relative) semblent aussi nécessaire à la compréhension du patron biogéomorphologique des tronçons étudiés.A partir de ces résultats des éléments de perspectives pour une gestion intégrée des rivières en tresses du district rhodanien sont proposés. / The landscape of the braided rivers is characterised by a rich and diversified mosaic of habitats. The variability of the braided riverscape depends upon the combination of bio-physical factors, which interact at the different spatial and temporal scales.We did a comparative analysis at the regional scale of 53 braided reaches selected in the Rhône basin district. We used a remote sensing-based approach.At first, we analysed the aquatic habitat and the river channel pattern. We showed that the braiding and aquatic habitat patterns do not depend only on the flow regime but also on some local scale conditions, such us the sediment regime and the presence of the “near-floor” groundwater.Secondly, we moved on the overall riverscape corridor, and we applied a diachronic analysis comparing the present state of reaches with their state at the mid of the last century. The results show that not all studied braided reaches are narrower today compared to the 1950s and that some reaches are even wider. It is linked to a combination of several factors, such as the geographical position of a reach in its catchment and the short-term evolution ruled by recent large floods, as well as the history of the catchment linked to human settlements.Then we focused on the evolutionary trajectories followed by a sub-set of 12 braided reaches through time, and we increased the temporal resolution, for a total of five dates per reach. The results show that reaches follow different trajectories depending on: the hydrological conditions at a given period (e.g. floods), the geographical position of a reach at the regional scale and the anthropic context. Additionally, it seems that also local conditions (in terms of topography, sedimentation, and soil moisture), play an important role in determining the biogeomorphological pattern of the studied reaches.From these results, we discussed some perspectives for the braided river management in the Rhône basin district.

Cette étude correspond au développement de deux approches de modélisation à base physique basées sur le concept de température d’équilibre pour simuler la température des cours d’eau à l’échelle du bassin de la Loire (105 km²). La performance de ces deux approches de modélisation est analysée via des chroniques horaires issues du réseau national thermique associé aux cours d’eau (RNT), mis en place par l’ONEMA en 2008. Une première partie est consacrée à l’étude de l’approche de modélisation stationnelle qui résout un bilan énergétique à l’échelle de la station. Cette approche a été testée selon une discrétisation simplifiée par ordre de Strahler puis selon une discrétisation à l’échelle du tronçon hydrographique. Elles simulent avec une très bonne précision la température horaire et journalière pour les grands cours d’eau où l’influence des conditions aux limites amont devient limitée. Une seconde approche dite « par propagation » basée sur une topologie de réseau est développée dans le but d’intégrer, à haute résolution spatiale et temporelle la propagation du signal thermique de l’amont vers l’aval des cours d’eau à une échelle régionale ce qui améliore la performance sur les cours d’eau situés en amont et de bien restituer la dynamique des profils thermiques longitudinaux des grands cours d’eau. / This work corresponds to the development of two physically based modeling approaches based on the equilibrium temperature concept to simulate the stream temperature at the Loire basin scale (105 km²). The performances of these two approaches are analyzed with hourly temperatures provided by the national thermal network associated with rivers (RNT), set up by the ONEMA in 2008. A first part focuses on the study of the 0D approach which solves the heat budget at the local scale. This approach has been tested with a simplified discretization by Strahler order and then with a discretization at the hydrographical reach scale. They simulated accurately hourly and daily temperatures for large rivers where the upstream influence becomes limited. The second part focuses on the approach by propagation based on a network topology in order to integrate the upstream-downstream propagation of the thermal signal with high spatial and temporal resolution at a regional scale which improves performances of rivers located near headwaters and to well reproduces the dynamics of longitudinal thermal profiles for large rivers.