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Search Results: 1 - 10 of 64433 matches for " Ant?nio Marciano da;Mello "
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Qualidade da água do Ribeir?o Lavrinha na regi?o Alto Rio Grande - MG, Brasil
Pinto, Daniel Brasil Ferreira;Silva, Antnio Marciano da;Mello, Carlos Rogério de;Coelho, Gilberto;
Ciência e Agrotecnologia , 2009, DOI: 10.1590/S1413-70542009000400028
Abstract: the main purpose of this work was to study the surface water quality behavior, continuously throughout the time, at the headwater watershed of the grande river, mg. the watershed drains into grande river area of 687 ha and is enclosed by the mantiqueira mountains. the samples were collected at six points in lavrinha stream, main tributary of the watershed, from may 2006 to january 2007, with a total of seven evaluations for each point. current watershed land use map was developed through gps device, based on field observations. the parameters evaluated were: hydrogen potential (ph), dissolved oxygen (do), electric conductivity (ec), salinity, temperature, biochemical oxygen demand (bod), chemical oxygen demand (cod), nitrate (no3-), ammonia (nh3), phosphorous (po4), turbidly, total soil, total dissolved soil (tds), fecal coliform (escherichia coli), total coliform. water quality index (wqi), proposed by "minas gerais state water resources institute" (igam), was calculated for all samples, classifying the water quality class according to conama resolution 357/05. the environmental conditions reflected on wqi values as well as on conama water quality classification. it was evidenced that the main parameter of the critical situation of the water quality at watershed was the fecal and total coliform, which is associated to livestock. although less important than coliform, do and bod are also limiting parameters at watershed.
Simula??o da variabilidade espacial da eros?o hídrica em uma sub-bacia hidrográfica de Latossolos no sul de Minas Gerais
Silva, Antnio Marciano da;Mello, Carlos Rogério de;Curi, Nilton;Oliveira, Polyanna Mara de;
Revista Brasileira de Ciência do Solo , 2008, DOI: 10.1590/S0100-06832008000500033
Abstract: simulation of water erosion spatial distribution is an important tool for soil conservation planning in watersheds, being an important application of the universal soil loss equation (usle) using interpolation principles, such as geostatistics. this study aimed to simulate spatial distribution of water erosion in a watershed of the alto rio grande (mg) region, applying geostatistical tools for mapping, considering different land use scenarios. water erosion was estimated by the usle applied to grid cells, weighing pedologic units and land use distribution in each cell. the topographical factor (ls) of the cells was obtained based on a digital elevation model of the sub-watershed, identifying length and main flow direction. mean annual rainfall erosivity in the region is 8,030 mj mm ha-1 h-1 year-1 and the underlying soil erodibility values were based on data from the literature. mapping was carried out considering the current land uses in the entire watershed, where eucalyptus was grown on degraded soils, grasses planted as pasture and corn tilled conventionally. under the current land uses, soil losses from the watershed were not relevant, except in areas covered with eucalyptus and grass on cambisol (inceptisol). in all simulations, the highest soil losses were verified on the eastern side of the watershed, especially for eucalyptus and conventional corn on cambisol and dystrophic red-yellow latosol (oxisol), where special soil conservation techniques are needed.
Aplicabilidade do lisem (limburg soil erosion) para simula??o hidrológica em uma bacia hidrográfica tropical
Gomes, Natalino Martins;Mello, Carlos Rogério de;Silva, Antnio Marciano da;Beskow, Samuel;
Revista Brasileira de Ciência do Solo , 2008, DOI: 10.1590/S0100-06832008000600025
Abstract: the most important parameters of the lisem model associated to surface runoff production (antecedent soil moisture (θap) and soil layer thickness), were calibrated by individual precipitation events in the marcela creek watershed, alto rio grande region, mg. the hydrological effects of different land-uses in the watershed were also simulated. the model was highly sensitivity to soil moisture, which was the most important calibration paramete. the influence of the water balance layer was related to the soil moisture during calibration. it was observed that the deeper the soil layer, the greater the soil moisture required to calibrate the model. results of simulation showed that the peak discharges were reduced under native forest, eucalyptus plantation and 35 months-old coffee plantation, respectively, by 37.6; 42.2 and 28.0 %, in the case of a precipitation event of 48 mm h-1. the results of the hydrological model lisem in hydrological simulations of direct surface runoff were satisfactory, suggesting that it may be used for hydrological behavior prediction in tropical watersheds after adequately calibrated.
Estabilidade temporal do conteúdo de água em três condi??es de uso do solo, em uma bacia hidrográfica da regi?o da Serra da Mantiqueira, MG
ávila, Léo Fernandes;Mello, Carlos Rogério de;Silva, Antnio Marciano da;
Revista Brasileira de Ciência do Solo , 2010, DOI: 10.1590/S0100-06832010000600024
Abstract: the description of soil hydrological processes is relatively complex, especially in the case of moisture, which is influenced by edaphic, topographic, climatic and vegetation factors. under field conditions, an adequate sampling strategy is required to estimate soil moisture, considering variations in time and space. to represent the soil moisture adequately with less sampling effort and cost, the concept of temporal stability has often been applied. this study was carried out with the objective of analyzing the temporal stability of the surface soil moisture (0-0.20 m layer) under three land uses in an experimental area in a catchment of the mantiqueira range region, state of minas gerais, brazil, in the dry and rainy seasons, identifying the most representative points for monitoring. greatest temporal stability was observed in the wetland, less under atlantic forest and intermediate in a pasture area. significant variation was also observed in the mean relative difference between the sampling periods, indicating that the characteristics of each site should be particularly considered to choose the points. in the pasture area, only one point could be identified to monitor both periods (rainy and dry). on the other hand, in the atlantic forest and wetland areas two points were identified, one specifically for the rainy and the other for the dry season; so an individual analysis for each season is recommended.
Continuidade espacial de chuvas intensas no estado de Minas Gerais
Mello, Carlos Rogério de;Viola, Marcelo Ribeiro;Mello, José Marcio de;Silva, Antnio Marciano da;
Ciência e Agrotecnologia , 2008, DOI: 10.1590/S1413-70542008000200029
Abstract: climate variables mapping, as intense rainfall, is very important to environmental management. although, statistical tools for spatial interpolation should be analyzed and characterized. this paper aims to analyze models and methods of semi-variogram modeling applied to intense rainfall with duration time of 20, 60, 360 and 1440 minutes and 5, 50 and 100 years of recurrence and consequently, giving support for its mapping, using kriging, in minas gerais state. exponential, spherical and gaussian semi-variogram models were tested based on weighted minimum square (wms) and maximum likelihood (ml) methods, using geor software. for the best model and method evaluation was considered the mean absolute error produced by cross-validation. for mean error similarity, it was considered the spatial degree of dependence and smaller nugget effect. visual adjustment of semi-variogram was also analyzed to complete the selection. exponential model was predominant in nine of twelve situations, followed by gaussian model in two situations and spherical for just one. weighted minimum square was the best adjust method in all situations. these results have indicated the exponential model adjusted by weighted minimum square to intense rainfall mapping for minas gerais state conditions.
Padr?o espa?o-temporal da umidade volumétrica do solo em uma bacia hidrográfica com predominancia de latossolos
ávila, Léo Fernandes;Mello, Carlos Rogério de;Mello, José Márcio de;Silva, Antnio Marciano da;
Revista Brasileira de Ciência do Solo , 2011, DOI: 10.1590/S0100-06832011000500034
Abstract: the spatial and temporal variability of soil moisture is high due to the influence of several environmental features and the land-use. the understanding of this variability plays a fundamental role in the modeling of surface runoff, soil erosion and sediment transport. this study aimed to evaluate the spatial and temporal patterns of surface soil moisture over the annual seasons, in a watershed with predominance of oxisols in the south of the state of minas gerais. for this purpose, the temporal stability concept was used as well as semivariogram models to compare the spatial structure of the adjusted semivariogram models. it was possible to detect a strong spatial dependence of soil moisture in the watershed, with a spatial dependence degree of > 80 %. besides, spatial pattern of the scaled semivariograms was similar for summer and fall, and different for winter and spring. based on these results, the spatial patterns of soil moisture differed over the year, and were most homogenous in the rainy season (summer). differences in the temporal patterns of soil moisture according to the season were verified, and also, the sperman test demonstrated a temporal bias in soil moisture i winter and spring.
Avalia??o técnica de um aspersor canh?o do tipo turbina
César, Júlio H. Fernandes;Silva, Antnio Marciano da;Rocha, Felizardo Adenilson;Mello, Carlos Rogério de;
Ciência e Agrotecnologia , 2004, DOI: 10.1590/S1413-70542004000400029
Abstract: this work intended to evaluate the technical performance of a gun sprinkler of the type turbine model "mercury" manufactured by società hidromecanica emiliana (sime) in italy and imported by the brazilian company metal lavras ltda. the study was developed with three nozzles (16, 20 and 22 mm), with service pressures of 250, 300, 350, 400, 450 and 500 kpa by the radial method test, with the purpose of verifying the influence of these parameters on distribution uniformity, application intensity, medium diameter of drops, reach radius and rotation uniformity. tables with values of average precipitation intensity, recommended spacing and values of uniformity coefficient were created, overcoming a deficiency demonstrated by manufacturer's catalog. it was verified that the medium diameter of drops increased with the decrease of the service pressure, and its behavior did not adapt to the classic model of gradual increase of the medium diameter of drops because several diameters were verified along of the wet radius. the potential equation was adjusted to the data of discharge versus pressure, with the nozzle of 16 mm being the most susceptible to the variations of service pressure. the water distribution profile followed the type "doughnut" and rectangular. the data of rotation uniformity demonstrated the efficiency of the rotation system of the turbine type. it was recommended the use of the tables produced, in substitution to the manufacturer's catalog.
Precipita??o provável para a regi?o de Madre de Deus, Alto Rio Grande: modelos de probabilidades e valores característicos
Junqueira Júnior, José Alves;Gomes, Natalino Martins;Mello, Carlos Rogério de;Silva, Antnio Marciano da;
Ciência e Agrotecnologia , 2007, DOI: 10.1590/S1413-70542007000300034
Abstract: nowadays, irrigation is one of the most important agricultural technique. therefore, this technique can not be the only source to supply water for crops, because the irrigation system may be over designed, increasing installation costs. one of alternatives to solve this problem is to analyze the probability of rainfall, decreasing costs and easing the irrigation management. this study purposes to characterize probable rainfall for madre de deus village, comparing four (4) probability distribution models (gama, normal, log-normal at 2 and 3 parameters). daily rainfall depths were totalized in consecutive periods of 10, 15 and 30 days, being evaluated for 13 different probability levels, using historical series of 57 year observation, between 1942 and 1999. kolmogorov-smirnov statistical test was applied to evaluate the adequacy of the adjusted probability models, towards to the most adequate model for each historical series. log-normal at 3 parameters was the most adequate for monthly periods and for fortnight and decennial periods, gama distribution was the best model.
Estimativa do escoamento superficial em uma bacia hidrográfica com base em modelagem dinamica e distribuída
Beskow, Samuel;Mello, Carlos Rogério de;Coelho, Gilberto;Silva, Antnio Marciano da;Viola, Marcelo Ribeiro;
Revista Brasileira de Ciência do Solo , 2009, DOI: 10.1590/S0100-06832009000100018
Abstract: knowledge on the surface runoff in watersheds is very important for a good conservation of natural resources. however, surface runoff is a complex and dynamic process, especially in the context of spatial variability. an application of the geographical information system (gis) tools in small grid cells is therefore adequate. this way, it is possible to consider the spatial behavior of variables associated to the origin of surface runoff. this study aimed to program the hydrological models scs-cn (scs-curve number) and cn - mms (cn - modified) based on the pc raster programming language and a reduced dataset, in distributed and dynamic approaches, to estimate the direct surface runoff in a watershed of oxissols, in the county of nazareno, region of campos das vertentes, minas gerais state. scs-cn model was applied structuring a cn-map linked to the soil infiltration capacity in the pcraster gis format. for the cn - mms model, we used other maps: saturated volumetric soil moisture content, initial volumetric soil moisture content and soil depth. for the simulation and evaluation of both models, 18 rainfall events that produced surface runoff in the hydrologic year 2004-2005 were used, and their respective surface runoff depths observed. the model performance was evaluated by sensitivity analyses, based on the mean error and root square error. based on these accuracy statistics, the calibration of the cn - mms model was better than in the original scs-cn model, since the initial soil moisture was taken into account. nevertheless, the adjustment of the models in the sig pcraster allowed the development of an effective and useful computer tool to simulate surface runoff, due to the possibility of establishing computer routines considering the problems elated to the spatial variability of data entries of the model.
Modelagem de atributos físico-hídricos do solo numa bacia hidrográfica da regi?o do Alto Rio Grande, MG
Mello, Carlos Rogério de;Gomes, Natalino Martins;Silva, Antnio Marciano da;Junqueira Junior, José A.;
Revista Brasileira de Ciência do Solo , 2007, DOI: 10.1590/S0100-06832007000500002
Abstract: this study aimed to develop models to estimate the two physical-hydric soil attributes, drainable porosity (pd) and water holding capacity (cta), based on easily and quickly measured physical attributes (particle-size distribution, water dispersible clay, total porosity, bulk density and particle density). disturbed and undisturbed soil samples were collected in the ribeir?o marcela watershed, from the of 0-15 cm layer, in grids of 240 x 240 and 60 x 60 m, totaling 165 sample points. linear multiple regression was applied, using variables that combined the different attributes with each other and the coefficients of variables estimated by the least-squares estimation, using the software sas. the models for cta and pd presented good statistical qualities, with high coefficients of determination, low estimate error and, statistical significance of estimated parameters. these results suggest that these models might be used for projects in the ribeir?o marcela watershed, which is representative of the oxisols domain in the alto rio grande region. they further provide region-specific technical information for agricultural and environmental projects and above all, for the parameterization of the hydrosedimentological simulation models in development.
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