Carbon dioxide and methane fluxes were measured between May 2003 and August 2004 on vegetated surfaces and pools of three peatlands located in the La Grande Riviere watershed, James Bay lowland, Quebec, Canada. Gas flux measurements were made using static chambers on a variety of sites in the three peatlands, chosen to represent the different biotypes present, from hummocks with water table position 35 cm below the surface to pools 100 cm deep. / Average CH4 fluxes for the different biotypes on vegetated surfaces sampled during summer 2003 ranged from 3.5 to 197 mg m-2 d-1 while summer 2004 average floating chamber pool fluxes ranged between 6.2 and 3165 mg CH4 m-2 d -1. Mean daily CH4 fluxes on vegetated surface are strongly correlated (r2 > 0.75) with summer average water table depth, greater fluxes occurring where water table is close to the surface. The vegetated surface CH4 fluxes were also correlated with peat temperature as fluxes increase with increasing peat temperature during the summer. / Most net ecosystem productivity values calculated for the different biotypes in the three peatlands showed release of CO2 during both early and mid growing season periods. An annual budget calculated for the LG2 peatland showed that the peatland emitted CO2 to the atmosphere at a rate of 0.77 g m-2 d-1. The overall release of CO 2 may have been caused in part by dry conditions in the peatlands during summer 2003, due to high temperature and low precipitation.

No description available.

[pt] A análise dos sistemas fluviais são de extrema importância na compreensão da evolução geomorfológica da paisagem, pois possuem características, seja no seu arranjo ou distribuição dos canais, que permitem elaborar os episódios que ocorreram ao longo do tempo. A quebra do continente Gondwana e seus múltiplos eventos até a consolidação do Rift Continental do Sudeste (RCS) implicou em uma mudança significativa no relevo sudeste e, consequentemente, nos sistemas de drenagens. Isto promoveu a reorganização dos sistemas de drenagens e uma nova dinâmica hidro-erosiva pelo rebaixado do nível de base na porção leste do continente com a consolidação do RCS. Diante do exposto, selecionou-se como estudo de caso a bacia do Rio Grande no Rio de Janeiro com o objetivo principal de entender o processo de evolução geomorfológica da bacia, a partir da organização da rede de drenagem e feições elementares da bacia frente aos eventos geológicos de formação e estruturação do substrato rochoso. A metodologia utilizada se baseia em trabalhos de gabinete, de campo e posterior análise dos dados gerados. Estes procedimentos visaram compreender a evolução do relevo na bacia do Rio Grande com base na correlação entre aspectos geológicos e geomorfológicos na organização do seu sistema fluvial. Pode-se inferir que a evolução geomorfológica da bacia do Rio Grande foi influenciada pelos múltiplos eventos tectônicos até a consolidação do RCS. Os dados demonstram forte controle do substrato rochoso na morfologia do relevo e na orientação da rede de drenagem. Os resultados das orientações dos fluxos de drenagem demonstram grande quantidade de rios nas orientações NE e NW. Acredita-se que a região correspondeu a um extenso planalto de altitude mais elevada que a atual, e sistema fluvial com direção predominante para noroeste/norte. A evolução da bacia do Rio Grande se deu através do avanço das drenagens atlânticas sobre o antigo Planalto Sudeste, através da erosão remontante e controladas pelo nível de base. / [en] Analysis of river systems are very important in understanding the geomorphological evolution of the landscape because they have characteristics, either in your arrangement or distribution channels, which enable the development of the episodes that have occurred over time. The break of the Gondwana Continent and its many events to the consolidation of Southeast Continental Rift resulted in a significant change in Southeast relief and hence the drainage systems. This promoted the reorganization of drainage systems and a new hydro-erosive dynamic by lowered the base level in the eastern portion of the continent with the consolidation of the Cenozoic RCS. Given the above, it was selected as a case study the basin of the Grande River in Rio de Janeiro with the main objective to understand the process of geomorphological evolution of the basin, from the drainage network organization and basic features of the front basin to events geological formation and structure of the bedrock. The methodology is based on office work, field and subsequent analysis of the data generated. These procedures were aimed at understanding the evolution of relief in the Rio Grande basin based on the correlation between geological and geomorphological aspects of the organization of its river system. It can be inferred that the geomorphological evolution of the Grande River basin was influenced by multiple tectonic events to the consolidation of RCS. The data demonstrate strong control of bedrock in relief morphology and orientation of the drainage system. The results of the guidelines of drainage flows demonstrate large number of rivers in the NE and NW directions. It is believed that the region corresponded to an extensive plateau higher than the current altitude, and river system with predominant direction north-west / north. The evolution of the Rio Grande basin was through the advancement of the Atlantic drainages on the old Plateau Southeast, through remontant erosion and controlled by the basic level.

La presente investigación evalúa el grado en que el dique-embalse Paso de las Piedras ha interrumpido la continuidad hidrológica del río Sauce Grande y cuantifica los impactos de la regulación hidrológica sobre el régimen de caudal, la morfología y la temperatura del agua del río aguas abajo del embalse. El trabajo de tesis presenta una evaluación integral y sistémica de los impactos del dique-embalse basada en el entendimiento de los procesos fluviales que ocurren aguas arriba del mismo. Además de proveer información sobre los impactos hidrológicos, morfológicos y térmicos de la construcción y operación del dique-embalse, este estudio genera nuevas series de datos climáticos e hidrológicos que proporcionan una importante plataforma sobre la cual basar futuras investigaciones de la cuenca del Sauce Grande. Por otra parte, este estudio implementa un marco metodológico aplicado al análisis hidro-geomorfológico de cuencas no aforadas que tiene un gran potencial de aplicación en otras cuencas de la región y en otras regiones semiáridas del mundo. / Despite the regional importance of the Sauce Grande River as main source for water supply and the large capacity of the Paso de las Piedras Reservoir, both the hydrology of the river basin and the effects of the impoundment on the river environment remain poorly evaluated. This study provides the very first assessment of the degree of flow regulation induced by the Paso de las Piedras Dam on the middle section of the Sauce Grande River, and quantifies its impacts on the hydrology, morphology and patterns of water temperature of the river downstream from the impoundment. In addition to providing new information on the response of regulated rivers to upstream impoundment and on the effects of impoundment on the Sauce Grande River specifically, this study generates spatial, climatic and hydrologic data and implements a methodological framework to hydrological assessment of ungauged basins. The methods include a set of procedures performed to generate data and a set of procedures performed to hydrological and morphological assessment. Methods used to generate data include (i) terrain modelling of the river basin, (ii) filling and modelling of climatic data, (iii) hydrological modelling of the upper river basin, and (iv) flow simulation and calculation. Methods used for hydrological and morphological assessment include (i) inspection of the water balance of the dam reservoir and quantification of the reservoir size-yield-performance relationships, (ii) quantification of the degree of hydrological alteration of the river downstream, (iii) classification of diurnal regimes of water temperature and quantification of their climatic sensitivity, and (iv) GIS-based diachronic analysis of change in the fluvial forms and the fluvial landscape. Results revealed that reservoir inflows are driven by varying climate conditions, whereas reservoir outflows are constrained by the dam purpose for water supply. Large volumes of water are yielded annually (73 % of the mean annual runoff) and the remaining volume is conserved within the reservoir for periods of drought. These patterns of flow regulation have seriously affected the hydrology and water quality of the river downstream. Floods were fully eliminated and the magnitude and frequency of high and low flows were reduced dramatically, with substantial increase in the duration of similar flow conditions. Furthermore, summer temperatures were depressed, winter temperatures were increased, and diurnal fluctuations were altered in both magnitude and timing. Analysis of the geomorphic response to altered hydrology revealed fluvial stability. Lateral and vertical channel activity was related to human intervention to facilitate the evacuation of dam outlets and spills more than to natural adjustments to reduced flow discharge and sediment load. The reduced flow, even if sediment-free, is incompetent to work its channel and at present, the downstream channel morphology is a relic of a fluvial environment created in the past under conditions of higher energy. The new climatic, hydrologic and morphologic information yielded herein has triple applicability: (i) it informs dam managers about the complex behaviour of the river system, (ii) it contributes to improve reservoir operation procedures while maintaining the overall integrity of the river system, and (iii) it provides a consistent scientific platform on which to base further research efforts conducting to an interdisciplinary framework of river restoration. Furthermore, the methods implemented in this research are widely transferable to hydrological assessment of ungauged basins worldwide, with special applicability to semiarid regions.

Cette recherche évalue le degré de régulation hydrologique induite par le barrage-réservoir Paso de las Piedras sur la Sauce Grande et quantifie les effets de cette régulation sur la hydrologie, la morphologie et la température de l'eau de la rivière en aval. Le travail de thèse consiste en une évaluation exhaustive et systématique des impacts du barrage-réservoir sur le système fluvial basée sur la compréhension des processus naturels qui se produisent en amont. En plus de fournir des informations sur les impacts hydrologiques, morphologiques et thermiques de la construction du barrage Paso de las Piedras et de l'exploitation de son réservoir, cette étude génère des séries de données climatiques et hydrologiques qui fournissent une base significative sur laquelle fonder des recherches futures. Par ailleurs, cette étude met en place un cadre méthodologique appliqué à l'analyse hydrogéomorphologique des bassins versants non jaugés qui a un grand potentiel d'application dans d'autres bassins de la région similaires ainsi que dans d'autres régions semi-arides du monde. / Despite the regional importance of the Sauce Grande River as main source for water supply and the large capacity of the Paso de las Piedras Reservoir, both the hydrology of the river basin and the effects of the impoundment on the river environment remain poorly evaluated. This study provides the very first assessment of the degree of flow regulation induced by the Paso de las Piedras Dam on the middle section of the Sauce Grande River, and quantifies its impacts on the hydrology, morphology and patterns of water temperature of the river downstream from the impoundment. In addition to providing new information on the response of regulated rivers to upstream impoundment and on the effects of impoundment on the Sauce Grande River specifically, this study generates spatial, climatic and hydrologic data and implements a methodological framework to hydrological assessment of ungauged basins.

Esta pesquisa apresenta alguns resultados do trabalho realizado com enfoque na arqueologia da paisagem em sítios arqueológicos localizados na Bacia Hidrográfica do Rio Turvo-Grande. Os procedimentos de campo foram iniciados no ano de 2011 e finalizados no ano de 2014, permitindo-nos avaliar o tipo e a intensidade de materiais arqueológicos, sua distribuição na paisagem, os aspectos geoambientais relevantes para a ocupação pretérita e os processos de formação atuantes nesses registros. Os dados colhidos em campo foram compilados em linguagem cartográfica, o que permitiu gerar informações espaciais dos sítios arqueológicos, bem como compreender sua possível relação com os geoindicadores locais. Os materiais arqueológicos recolhidos foram analisados em laboratório, levantando questões importantes sobre a sua produção, o seu uso e a sua espacialidade intrassítio. Os sítios arqueológicos trabalhados no âmbito dessa pesquisa foram correlacionados ao contexto arqueológico regional. A análise multiescalar e multidimensional desse contexto permitiu identificar alguns padrões socioespaciais que auxiliaram na compreensão do processo de habitar e transformar às paisagens do norte do estado de São Paulo. / This research presents some results of the work fulfilled with focus on the landscape archaeology in archeological sites located in the Turvo-Grande River Basin. Field procedures were initiated in 2011 and finalized in 2014, allowing us to evaluate the type and intensity of archaeological materials, their distribution in the landscape, the geoenvironmental aspects relevant to the past occupation and the formation processes in these records. The data collected in the field were compiled in cartographic language, which allowed to engender spatial information of the archaeological sites, furthermore to understand its possible relation with the local geoindicators. The collected archaeological materials were analyzed in the laboratory, raising important questions about its production, its use and its intrasite spatial. The archaeological sites worked within this research were correlated to the regional archaeological context. The multiscale and multidimensional analysis of this context allowed the identification of some socio-spatial patterns that helped to understand the process of dwelling and transforming the landscapes of the north of the state of São Paulo.

From the Proceedings of the 1976 Meetings of the Arizona Section - American Water Resources Assn. and the Hydrology Section - Arizona Academy of Science - April 29-May 1, 1976, Tucson, Arizona / Energy budget evaluations of evapotranspiration from saltcedar were carried out on the flood plain of the Rio Grande River, near Bernardo, New Mexico. The site was adjacent to the Bureau of Reclamation's lysimeter study of water use by saltcedar. The energy budget for the cloudless day of June 14, 1975, revealed that energy gains from net radiation totaled 432 cal/cm² , while energy losses (in cal/cm2 ), were 14 to stored energy, 31 to convection, and 387 to evapotranspiration (ET). The energy loss to ET is equivalent to the latent energy contained in about 6.5 mm of water. The energy budget values are reasonable for a phreatophyte community in a semi-arid environment. The latent energy loss compares favorably with 401 cal/cm² measured by three lysimeters, although there were discrepancies in timing and amounts of loss among the individual lysimeters. The mean canopy diffusion resistance was 1.90 sec/cm over a 10-hour daytime period on June 14. The mean resistance was combined with vapor pressure deficit to predict lysimeter ET on three subsequent days. The agreement was within 12 percent, which suggests that diffusion resistance may be useful for simple ET predictions.