• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 18
  • 15
  • 3
  • 2
  • 1
  • 1
  • 1
  • 1
  • 1
  • 1
  • 1
  • Tagged with
  • 41
  • 12
  • 10
  • 9
  • 9
  • 8
  • 7
  • 6
  • 6
  • 6
  • 5
  • 5
  • 5
  • 4
  • 4
  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
11

Habitat Type and Ecotone Effects on Biodiversity of Hymenoptera, Diptera, and Lepidoptera

Wayne, Heather January 2015 (has links)
No description available.
12

Influence du paysage sur les communautés de micromammifères hôtes d'agents infectieux transmis par les tiques / Influence of the landscape on the small mammal communities as hosts of tick-borne infectious agents

Perez, Grégoire 31 May 2016 (has links)
Une recrudescence de l’émergence ou de la réémergence de maladies infectieuses touchant l’homme ou ses animaux domestiques a été constatée ces dernières décennies. La majorité de ces maladies sont zoonotiques, c’est à dire originaires de la faune sauvage, et impliquent souvent un vecteur dans leur cycle de transmission. Parallèlement, des changements d’utilisation du sol en lien avec une intensification agricole modifient les paysages. L’objectif de cette thèse était d’améliorer l’état des connaissances de l’influence du paysage sur les relations entre hôtes, vecteurs et pathogènes. En Europe, les micromammifères peuvent abonder dans la plupart des écosystèmes terrestres, ce qui en fait des hôtes de choix pour les tiques généralistes Ixodes ricinus. Ils sont aussi des réservoirs d’agents infectieux transmis par les tiques. Les résultats de la thèse sont basés sur deux ans d’échantillonnage, printemps et automne, des micromammifères et des tiques dans différents paysages. Nous avons aussi recherché trois agents infectieux qu’ils hébergent et transmettent : Borrelia burgdorferi sensu lato (maladie de Lyme), Anaplasma phagocytophylum (anaplasmose) et Theileria (Babesia) microti (piroplasmose), ce dernier n’ayant pu être exploité en raison de sa trop faible prévalence. Les 24 sites d’échantillonnage étaient pour moitié en cœur ou en lisière de forêt et pour moitié dans des paysages agricoles offrant un gradient d’occupation du sol et d’ouverture du paysage. Le meilleur facteur explicatif de l’abondance de nymphes est la présence de larves d’I. ricinus l’année précédente. Les résultats indiquent aussi une relation entre le nombre de larves portées par les mulots sylvestres (Apodemus sylvaticus ; 76,5% des captures) et l’abondance de nymphes l’année suivante. Les campagnols roussâtres (Myodes glareolus ; 22,3% des captures) portaient moins de larves au printemps, certainement du fait d’une résistance acquise aux tiques des individus hivernants. Bien que ces deux espèces réagissent différemment aux variables de composition et de configuration du paysage, les abondances de nymphes n’étaient pas expliquées par ces variables. D’autres hôtes, comme les chevreuils (Capreolus capreolus), et des facteurs microclimatiques et météorologiques influencent donc probablement aussi les abondances et la distribution des tiques dans le paysage. La richesse spécifique des hôtes et l’abondance des campagnols roussâtres, trois fois plus infectés que les mulots sylvestres, amplifieraient les prévalences d’A. phagocytophylum de ces deux espèces de rongeurs. A l’inverse, la fragmentation du paysage, via la réduction de la taille des populations d’hôtes, semble agir négativement sur ces prévalences. Aucun patron spatial évident n’a été observé pour B. burgdorferi s.l.. De même, aucun lien n’a pu être fait entre les prévalences des rongeurs et celles des nymphes d’I. ricinus. Ces résultats suggèrent un rôle probable d’espèces de tiques plus spécialistes, I. trianguliceps et I. acuminatus, dans la circulation des agents infectieux étudiés, soulignant l’intérêt qu’il pourrait y avoir à considérer l’ensemble de la communauté de vecteurs dans de futures études. L’ensemble des résultats soulignent aussi l’importance qu’il y aurait à considérer un maximum d’hôtes micromammifères réservoirs, même peu abondants, à l’échelle du paysage pour mieux comprendre la transmission de ces maladies infectieuses vectorielles. / An increase in the emergence or in the reemergence of infectious diseases of human and his domestic animals has been observed in the last decades. Most of these diseases are zoonotic, i.e. originated from wildlife, and imply often a vector for their transmission. At the same time, land use changes linked to agricultural intensification have modified the landscapes. The aim of the thesis was to enhance the state of knowledge on the influence of the landscape on the relationships between hosts, vectors and pathogens. In Europe, small mammals can be abundant in most of terrestrial ecosystems; they are thus preferred hosts for the generalist tick species Ixodes ricinus. They are also reservoirs of tick-borne infectious agents. The results of this thesis are based on two years of sampling, in spring and autumn, of small mammals and ticks in different landscapes. We analyzed them for three of the infectious agents they host and transmit: Borrelia burgdorferi sensu lato (Lyme disease), Anaplasma phagocytophylum (anaplasmosis) and Theileria (Babesia) microti (piroplasmosis), this last one could not be exploited because of too low prevalence. The 24 sampling sites were half in the core or the edge of a forest and half in agricultural landscapes with a gradient of land cover and of landscape openness. The best explanatory variable for nymph abundance was the presence of I. ricinus larvae the previous year. The results also indicate a relationship between the number of larvae attached on wood mice (Apodemus sylvaticus ; 76,5% of the catches) and the abundance of nymphs the following year. Bank voles (Myodes glareolus ; 22,3% of the catches) harbored less larvae in spring, certainly because of an acquired resistance to ticks in the overwintering individuals. Despite that these two species react differently to the composition and configuration features of the landscape, the abundances of nymphs were not related to these features. Other hosts, like roe deer (Capreolus capreolus), meteorological and microclimatic factors probably influence the abundances and the distribution of ticks in the landscape. The host specific richness and the abundance of bank voles, which were threefold more infected than wood mice, likely amplified the prevalence of A. phagocytophylum of these two rodent species. Conversely, landscape fragmentation, via the reduction of host population sizes, seems to act negatively on this prevalence. No clear spatial pattern was observed for B. burgdorferi s.l.. Likewise, no link could be established between the prevalence of the rodents and the prevalence of the nymphs. These results suggest a possible role of more specialist tick species, I. trianguliceps and I. acuminatus, in the circulation of the studied infectious agents, emphasizing the possible interest of considering the whole vector community in further studies. The results also emphasize the importance of considering a maximum of small mammal reservoir hosts, even at low abundances, at the landscape scale to better understand the transmission of these vector-borne infectious diseases.
13

Diatoms as tools for inferring changing environmental gradients in coastal, freshwater wetlands threatened by saltwater intrusion

Mazzei, Viviana 30 March 2018 (has links)
Saltwater intrusion alters the natural salinity and phosphorus (P) gradients in the oligotrophic, freshwater wetlands located near coastlines of the Caribbean Basin with important consequences to the structure and function of key ecosystem components, including plants, soil microbes, and periphyton. Periphyton communities, particularly diatoms, are extremely sensitive to water quality changes and can serve as excellent bioindicators; however, little is known about their use in detecting novel rates of saltwater intrusion into coastal, freshwater wetlands. I examined the individual and combined effects of elevated salinity and P on periphyton functional processes and diatom composition by conducting transect surveys along salinity and P gradients in the southern Everglades, as well as through mesocosm studies in which salinity and P were experimental manipulated. I demonstrated that conductivity (a proxy for salinity) and P gradients drive spatial patterns in diatom assemblage structure in the southern Everglades and that these assemblages have relatively low conductivity (2 mS cm-1) and total P thresholds (82 µg g-1). These findings were supported by the experimental work which showed that monthly pulses of elevated salinity only ~1 ppt above ambient was sufficient to cause significant shifts in periphytic diatom assemblages along with reduced periphyton productivity, total carbon, and nutrient content. The addition of P to freshwater and salt-treated periphyton significantly elevated mat total P, underscoring the P-uptake efficiency of periphyton. Surprisingly, addition of P to freshwater periphyton did not elicit significant functional or compositional responses, although chlorophyll-aconcentrations and accumulation rates tended to be higher with P. Similar chlorophyll-atrends were observed for salt-treated mats with added P, but these mats also exhibited significantly higher gross primary productivity and net ecosystem productivity compared to all other treatments and a diatom assemblage distinct from any other treatment. This research provides new and valuable information regarding periphyton dynamics in response to changing water sources that will allow us to extend the use of periphyton, and their diatom assemblages, as tools for environmental assessments related to saltwater intrusion in the southern Everglades and other karstic, freshwater wetlands.
14

Modelling Vegetation Cover Types Using Multiseasonal Remotely Sensed Data to Compare Ecotones at Multiple Spatial and Spectral Resolutions

Patraw, Kimberly 01 May 1997 (has links)
The Army National Guard Bureau has implemented a cooperative project with Utah State University to help with the use, display, and evaluation of environmental data for maintaining land condition. Camp Grayling, Michigan, is comprised of deciduous and evergreen forest types. Use of remote sensing for classification has been limited in this region due to the difficulty of species-level classification using single-date remote-sensing techniques . Also, remote sensing has traditionally focused on mapping homogenous zones rather than vegetation boundaries, while one of the concerns for land managers is the nature of vegetation edges (ecotones). This study analyzed each season and band from multiseasonal satellite imagery for their contribution to separating vegetation type and density classes. Then spectral reflectance values for each vegetation and density class were used in discriminant models that define vegetation cover types and densities. These models were then tested against points within 200 m of vegetation boundaries to determine the performance of the models at edges of vegetation types . The reflectance values for vegetation types on Landsat Thematic Mapper (TM), Landsat MultiSpectral Sensor (MSS), and Advanced Very High Resolution Radiometer (AVHRR) imagery were used. Single-band separability decreased with decreasing resolution of the remote sensing data, and the number of spectral bands that could separate means of vegetation and density cover classes was much greater than expected . Winter bands provided more separability than expected for density classes . A VHRR data were shown to provide very little separation and were not included in the discriminant analysis. In the evaluation of the discriminant models, both resubstitution and crossvalidation tests showed that TM and MSS were nearly equal in their ability to discriminate cover types and densities. At the vegetation boundary zones, classification accuracy increased with increasing distance from the edge. These results are encouraging for future classification and monitoring of ecotones using satellite imagery, as picture elements (pixels) of ecotones generally exhibit the characteristics of a mixing of the boundary vegetation types. Further investigation into fuzzy set classification and ecotone classification and monitoring appears warranted.
15

Soil organic matter dynamics and methane fluxes at the forest-tundra ecotone in Fennoscandia /

Sjögersten, Sofie, January 2003 (has links)
Diss. (sammanfattning) Uppsala : Univ., 2003. / Härtill 5 uppsatser.
16

Inuit knowledge and perceptions of the land-water interface

Heyes, Scott. January 1900 (has links)
Thesis (Ph.D.). / Written for the Dept. of Geography. Title from title page of PDF (viewed 2007/08/29). Includes bibliographical references.
17

Relation of Missouri river flows to sandbar morphology with implications for selected biota

Tracy-Smith, Emily. January 2006 (has links)
Thesis (M.S.) University of Missouri-Columbia, 2006. / The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Title from title screen of research.pdf file viewed on (June 27, 2007) Includes bibliographical references.
18

Fragmentos de florestas Atlânticas no Rio Grande do Norte: relações estruturais, florísticas e fitogeográficas. / Atlantic forests fragments in the Rio Grande do Norte State: structural, floristic and phytogeographical relationship

Cestaro, Luiz Antonio 03 June 2002 (has links)
Made available in DSpace on 2016-06-02T19:30:16Z (GMT). No. of bitstreams: 1 Tese_Doutorado_Luiz_Antonio_Cestaro.pdf: 1836363 bytes, checksum: 7144b2eb6257aa1bcf28268b704a1a79 (MD5) Previous issue date: 2002-06-03 / Financiadora de Estudos e Projetos / The knowledge about Brazilian Atlantic forests in its northerm limit of distribution, in the transition to Caatingas, is will very scarce, mainly in the Rio Grande do Norte State, were the small and rare forest fragments still existing are almost totally ecological and phytogeographically ignored. We suppose that this fragments occurs on sandy, dystrophic and deep soils and that the rain gradient is the main factor to determinate different patterns of vegetation types in the east-west direction. The aims of this work are to characterize floristic and structurally the tree layer of four forest fragments ant to determine its relationships with the nearest phytogeographical provinces. Three semi-deciduous and one deciduous fragments were analyzed, all near of the Natal City, almost perpendicular to the coast. Two fragments, a semi-deciduous and the deciduous, were stretched in two parts according to the relief differences. The point-centered quarter method was used to sample, in the six areas, the standing and living trees with stem perimeter at 1,3 m heigth equal or superior to 10 cm. To each tree were considered: the species name, height estimated, stem perimeter(s) and the distance to the point. Data were worked at spreadsheets to obtain total density, specific and total basal areas and relatives frequency, density, dominance, importance value and dominance value, H'diversity and J' equability were obtained to each area. To a semi-deicuous forest and to the deciduous one the proportion of species connected to different phytogeographical provinces was obtained. The structure and the floristic composition of the areas were compared. The structure, by means of tree heights, stem diameter and basal area and the floristic composition, by means of Sorensen and Czekanowski similarity indices. Cluster analysis (UPGMA) was used to classify the areas. In all areas 117 species were observed, being 89 in the semi-deciduous forest and 66 in the deciduous forest. Fabaceae and Mytaceae are the richest families. The tree densities vary from 2403 to 1526 individual/ha. The semi-deciduous forests generally are tallest and have a biggest basal area (from 22,29 to 39,84 m2/ha) than deciduous forest, with a basal area of 15,87 m2/ha. The diversity vary between 2,8 and 3,27 nat/individual and the equability between 0,77 and 0,82 to the semi-deciduous forests, while to the deciduous forest the H' values are 3,19 and 3,26 nat/individual and the j' values are 0,79 snf 0.86. Two floristic groups were obtained by classification. One compounded by semi-deciduous forests and another with the deciduous one. The semi-deciduous forests have the highest proportion of species associated to the Atlantic province and a high proportion of wide distribution. Neotropical species, especially in the gallery forests of the Cerrados. Few species are shared with the Caatingas. The deciduous forest has similiar proportions of species from Atlantic, Caatingas provinces of wide distribution species, being considered as transitional vegetation between the first two provinces. The rain gradient determines the distinction of semi-deciduous forest from the deciduous one, while the edaphic and geomorphologic factos are responsible by different semi-deciduous forest types. The floristic and structural variability observed in a semi-deciduous fragment is associated to the relief and soil variations, being the upper area a transition to the coastal "tabuleiros" savannas, while the lower area, a transition to the gallery forest. The deciduous forest presents low structural internal variability, but with typical species of dry forests in the upper area and typical species of Caatingas in the lower area. The results point out the complexity of the vegetational mosaic in the transitional area between Atlantic and Caatingas provinces in the Rio Grande do Norte State / O conhecimento das florestas atlânticas brasileiras em seu limite setentrional de distribuição, na transição para as Caatingas, ainda é bastante escasso, sobretudo no Rio Grande do Norte, onde os pequenos e raros fragmentos florestais existentes são quase totalmente desconhecidos ecológica e fitogeograficamente. Supõe-se que esses fragmentos ocorram sobre solos essencialmente arenosos distróficos e profundos e que o gradiente de precipitação seja o principal fator a determinar distintos padrões de vegetação no sentido leste-oeste. Os objetivos deste trabalho são caracterizar florística e estruturalmente o componente arbóreo de quatro fragmentos florestais e estabelecer suas relações com as províncias fitogeográficas com influência local. Foram analisados três fragmentos de florestas semidecíduas e um fragmento de floresta decídua localizados à cidade de Natal, RN, quase alinhados perpendicularmente à linha de costa. Dois fragmentos, um de floresta semidecídua e outro de floresta decídua, foram divididos em um trecho superior e outro inferior em função do relevo. Os solos em cada fragmento foram classificados e caracterizados granulométrica e quimicamente. O método dos quadrantes centrados em um ponto utilizado para amostrar, nas seis áreas, as árvores em pé com perímetro de caule a 1,3 m de altural igual ou superior a 10 cm. Para cada árvore foram considerados: espécie à qual pertence, altura estimada, perímetro (s) do (s) caule (s) e menor distância até o ponto. Os dados foram trabalhados em planilha eletrônica para a obtenção de densidade total, área basal específica e total e frequência, densidade, dominância, valor de importância e valor de cobertura relativos. Foram calculados para cada mata a diversidade H' e a equabiblidade J'. Para uma mata semidecídua e para a mata decídua foram avaliadas as proporções de espeécies associadas a diferentes províncias fitogeográficas. A comparação entre matas levou em consideração a estrutura, através da altura das árvores, dos diâmetros de caule e das áreas basais, a composição de espécies, envolvendo as similaridades de Sorensen e Czekanowski e a classificação através de dendogramas, construídos utilizando UPGMA. Foram observadas 117 espécies arbóreas no conjunto de matas, sendo 89 nas florestas semidecíduas e 66 na floresta decídua. Fabaceae e Myrtaceae são as famílias mais ricas em espécies. A densidade nas matas varia entre 2403 indivíduo/ha e 1526 indivíduo/ha. As florestas semidecíduas apresentam, em geral, maiorporte e maior área basal (22,29 m2/ha a 39 m2/ha) do que a floresta decídua, com área basal de 15,87 m2/ha. A diversidade varia entre 2,8 e 3,27 nat/indivíduo e a equabilidade entre 0,77 e 0,82 para as florestas semidecíduas, enquanto para a floresta decídua os valores de H' são 3,19 e 3,26 nat/indivíduo e de J', 079 e 0,86. A calssificação das matas permitiu a distinção de dois conjuntos florísticos, um composto pelas matas semidecíduas e outro por uma mata decídua. As florestas semidecíduas apresentam a maior proporção de espécies associadas à província Atântica, uma elevada proporção de espécies com ampla distribuição neotropical, sobretudo pelas matas de galeria dos Cerrados e poucos representantes das Caatingas. A floresta decídua apresenta proporções semelhantes de espécie das províncias Atlânticas, das Caatingas e com ampla distribuição neotropical, sendo considerada como vegetação de transição entre as duas primeiras províncias. O gradiente pluviométrico determina a distinção entre florestas semidecíduas e decíduas, enquanto as caracterísiticas edáficas e geomorfológicas são responsáveis pelo estabelecimento de diferentes tipos de florestas semidecíduas. As variãções internas, tanto florísticas quanto estruturais, observadas num dos fragmentos de floresta semidecídua estão associadas ao relevo e ao solo, sendo o trecho superior considerado como uma transição para as savanas dos tabuleiros costeiros, enquanto o trecho inferior, uma transição para as matas de galeria. A floresta decídua apresenta baixa variação estrutural interna, com espécies características de florestas decíduas no trecho topograficamente mais alto e espécies associadas às Caatingas no trecho mais baixo. Os resultados ressaltam a complexidade do mosaico vegetacional na zona de transição entre as províncias Atlântica e das Caatingas no Rio Grande do Norte
19

Características físicas e químicas das águas superficiais e subterrâneas (nas proximidades do canal), dos ribeirões do Moquém e Água Clara (Médio Tietê Superior - SP), em função das variações hidrológicas / Physical and chemical characteristics of the superficial and groundwaters (in the proximities of the channel), of the Moquém and Água Clara streams (Medium Superior Tietê - SP), in function of the hydrological variations

Bubel, Anna Paola Michelano 17 December 2003 (has links)
As teorias sobre o funcionamento dos sistemas lóticos evoluíram nos últimos anos, os condicionantes geológicos/geomorfológicos como também as regiões de transição têm recebido importância crescente. As regiões de transição merecem destaque uma vez que os sistemas lóticos estabelecem interações de fluxo com os ambientes vizinhos (atmosféricos, terrestres e subterrâneos) e a troca de materiais estabelecida entre esses sistemas é importante para a definição de suas características. As bacias hidrográficas dos ribeirões do Moquém e Água Clara, estudadas no presente trabalho, apresentam: proximidade geográfica além de semelhanças morfológicas e climáticas, porém diferem quanto aos aspectos geológicos e geomorfológicos. A partir desses aspectos, a presente pesquisa investigou as flutuações sazonais nas relações físicas, química e hidrológicas entre águas superficiais e subterrâneas (adjacências do canal), na região do baixo curso dos ribeirões já citados. Foram escolhidos dois trechos em cada ribeirão para a realização de: (1) inventário hidrológico mensal, a partir de medidas de velocidade de escoamento, vazão e do nível de água em poços instalados na região marginal dos rios nos trechos de estudo; (2) caracterização física e química de testemunhos da região marginal dos rios, onde foram utilizadas amostras obtidas durante a perfuração dos poços; (3) amostragens das águas superficiais subterrâneas no mesmo período do inventário para a determinação das características físicas e químicas das mesmas. Os resultados destacaram os seguintes itens. O fluxo de base garantiu vazões regulares e elevadas ao ribeirão Água Clara, ao mesmo tempo que as vazões foram quase insignificantes no ribeirão do Moquém, fato esse que apresenta importância ecológica. A química das águas dos ribeirões estudados é distinta, possivelmente, como resposta às características naturais das bacias. Nos dois trechos de estudo, as águas superficiais e subterrâneas apresentaram diferenças físicas e químicas, o que pode indicar que as trocas entre o canal do rio e suas adjacências são pequenas e/ou lentas. Com base nas observações desta pesquisa, recomenda-se que as características quantitativas e qualitativas, distintas, entre as águas dos ribeirões do Moquém e Água Clara devem ser avaliadas durante a tomada de decisões em processos de gestão de recursos hídricos. / The theories on the operation of the lotic systems developed over the recent years, the geological/geomorphological condicionantes as well as the transition areas have been receiving growing importance. The transition areas deserve prominence once the lotic systems establish flow interactions with the neighboring environment (atmospheric, terrestrial and undergrounds) and the exchange of materials established among those systems is important in order to define their characteristics. The watersheds of the Moquém and Água Clara streams, studied in the present work, present: geographical proximity besides morphologic and climatic similarities, however they differ as far the geological and geomorphological aspects are concerned. From those aspects, the present research investigated the seasonal flutuations in physical, chemical and hydrological relationships among superficial and groundwaters (adjacencies of the channel), in the area of the low course of already mentioned the streams. It was chosen two reaches in each stream in order to accompish: (1) monthly hydrological inventory, starting from measures of drainage speed, discharge and water level in wells installed in floodplain of the streams in the studied reaches; (2) physical and chemical characterization of testimonies in floodplain of the rivers, where samples were used obtained during the perforation of the wells; (3) samplings of the superficial and groundwaters in the same period of the inventory in order to determinate the physical and chemical characteristics of same them. The results notice the following items. The base flow guaranteed regular and high discharges in the Água Clara stream, at the same time that the discharges were almost insignificant in the ribeirão of Moquém, a fact that presents ecological importance. The chemistry of the waters of the studied streams is different, possibly, as an answer to the natural characteristics of the watersheds. In the two studied reaches, the superficial and groundwaters presented physical and chemical differences, what can indicate that the changes between the channel of the river and it adjacencies are small and/or slow. Based on this research observations, it is recommended that the quantitative and qualitative, characteristics, between the waters of the Moquém and Água Clara streams should be appraised during the moment the decisions are made on management processes of hydric resources.
20

Características físicas e químicas das águas superficiais e subterrâneas (nas proximidades do canal), dos ribeirões do Moquém e Água Clara (Médio Tietê Superior - SP), em função das variações hidrológicas / Physical and chemical characteristics of the superficial and groundwaters (in the proximities of the channel), of the Moquém and Água Clara streams (Medium Superior Tietê - SP), in function of the hydrological variations

Anna Paola Michelano Bubel 17 December 2003 (has links)
As teorias sobre o funcionamento dos sistemas lóticos evoluíram nos últimos anos, os condicionantes geológicos/geomorfológicos como também as regiões de transição têm recebido importância crescente. As regiões de transição merecem destaque uma vez que os sistemas lóticos estabelecem interações de fluxo com os ambientes vizinhos (atmosféricos, terrestres e subterrâneos) e a troca de materiais estabelecida entre esses sistemas é importante para a definição de suas características. As bacias hidrográficas dos ribeirões do Moquém e Água Clara, estudadas no presente trabalho, apresentam: proximidade geográfica além de semelhanças morfológicas e climáticas, porém diferem quanto aos aspectos geológicos e geomorfológicos. A partir desses aspectos, a presente pesquisa investigou as flutuações sazonais nas relações físicas, química e hidrológicas entre águas superficiais e subterrâneas (adjacências do canal), na região do baixo curso dos ribeirões já citados. Foram escolhidos dois trechos em cada ribeirão para a realização de: (1) inventário hidrológico mensal, a partir de medidas de velocidade de escoamento, vazão e do nível de água em poços instalados na região marginal dos rios nos trechos de estudo; (2) caracterização física e química de testemunhos da região marginal dos rios, onde foram utilizadas amostras obtidas durante a perfuração dos poços; (3) amostragens das águas superficiais subterrâneas no mesmo período do inventário para a determinação das características físicas e químicas das mesmas. Os resultados destacaram os seguintes itens. O fluxo de base garantiu vazões regulares e elevadas ao ribeirão Água Clara, ao mesmo tempo que as vazões foram quase insignificantes no ribeirão do Moquém, fato esse que apresenta importância ecológica. A química das águas dos ribeirões estudados é distinta, possivelmente, como resposta às características naturais das bacias. Nos dois trechos de estudo, as águas superficiais e subterrâneas apresentaram diferenças físicas e químicas, o que pode indicar que as trocas entre o canal do rio e suas adjacências são pequenas e/ou lentas. Com base nas observações desta pesquisa, recomenda-se que as características quantitativas e qualitativas, distintas, entre as águas dos ribeirões do Moquém e Água Clara devem ser avaliadas durante a tomada de decisões em processos de gestão de recursos hídricos. / The theories on the operation of the lotic systems developed over the recent years, the geological/geomorphological condicionantes as well as the transition areas have been receiving growing importance. The transition areas deserve prominence once the lotic systems establish flow interactions with the neighboring environment (atmospheric, terrestrial and undergrounds) and the exchange of materials established among those systems is important in order to define their characteristics. The watersheds of the Moquém and Água Clara streams, studied in the present work, present: geographical proximity besides morphologic and climatic similarities, however they differ as far the geological and geomorphological aspects are concerned. From those aspects, the present research investigated the seasonal flutuations in physical, chemical and hydrological relationships among superficial and groundwaters (adjacencies of the channel), in the area of the low course of already mentioned the streams. It was chosen two reaches in each stream in order to accompish: (1) monthly hydrological inventory, starting from measures of drainage speed, discharge and water level in wells installed in floodplain of the streams in the studied reaches; (2) physical and chemical characterization of testimonies in floodplain of the rivers, where samples were used obtained during the perforation of the wells; (3) samplings of the superficial and groundwaters in the same period of the inventory in order to determinate the physical and chemical characteristics of same them. The results notice the following items. The base flow guaranteed regular and high discharges in the Água Clara stream, at the same time that the discharges were almost insignificant in the ribeirão of Moquém, a fact that presents ecological importance. The chemistry of the waters of the studied streams is different, possibly, as an answer to the natural characteristics of the watersheds. In the two studied reaches, the superficial and groundwaters presented physical and chemical differences, what can indicate that the changes between the channel of the river and it adjacencies are small and/or slow. Based on this research observations, it is recommended that the quantitative and qualitative, characteristics, between the waters of the Moquém and Água Clara streams should be appraised during the moment the decisions are made on management processes of hydric resources.

Page generated in 0.1356 seconds