Navegando por Assunto "Medidores de fluxo"

Agora exibindo 1 - 4 de 4

Acesso aberto (Open Access)
Análise do comportamento da precipitação e da vazão em bacias hidrográficas Amazônicas
(Universidade Federal do Pará, 2016-03-14) HACHEM, Bruno Penna; FERNANDES, Lindemberg Lima; http://lattes.cnpq.br/4641468846318922
The aim of this study was to analyze the behavior of precipitation and flow in two river regions of the state of Pará, where Northern Corridor and Coast Northeast Atlantic. Both have the same rainfall and physical properties of the bowls are similar, being different only in regard to level and vegetable preservation area. For this study, we used 7 gauged stations and 7 rainfall in the Northern Corridor and 6 fluviometric 6 and rainfall in Costa Northeast Atlantic. After collecting the data in HIDROWEB, they were organized in Microsoft Excel spreadsheets software for application of Mann Kendall and Spearman tests, which stated that there is no trend in the series analyzed (α=5%). Was detected that the density of fluviometric and rainfall stations is low , according to the thresholds established by WMO. The Pearson correlation coefficients showed up "strong" between precipitation and flow of the areas studied, which also suffer influence of climatic phenomena (El Niño and La Niña). It was possible to consider that in the most preserved region, the time lag between the maximum rainfall and the maximum flow rate averaged two months, while the region with greater human action this time was an average of 1 month.
Acesso aberto (Open Access)
Modelo vazão-velocidade para avaliação de potencial hidrocinético
(Universidade Federal do Pará, 2018-05-25) CRUZ, Josias da Silva; BLANCO, Claudio José Cavalcante; http://lattes.cnpq.br/8319326553139808
The Brazilian hydrological information network provides daily flow data; however, daily velocity information is not available in historical series. The inventory of river velocities is important for many applications, and one of them is the study of hydrokinetic potential, including downstream of hydroelectric plants. Therefore, the work proposes a model called Flow-Velocity that determines the average daily velocity, the geometric form and the distribution of the logarithmic velocity profile of the cross section of rivers from daily flow data. The model was initially applied in a small river basin with flow data and the validation was performed using the mean square error (RMSE), the relative mean square error (RRMSE), the standard deviation of observation (RSR) and the percentage of bias PBIAS. Subsequently, the model was applied to the river basins of the Amazonas, São Francisco and Paraná rivers (Brazil's largest basins), using the highest and lowest flows in the historical series. The highest and lowest average speed found in the Amazon River was 2.27 ms-1 and 0.735 ms-1 in the Óbidos cross-section for a flow of 266 897 m³s-1 and 72 480 m³-1, respectively. The main contributors to the Amazon River, with the exception of the Trombetas, Madeira and Xingu rivers, present average daily speeds below 2 ms-1 for the flood period, but in the dry season the average daily speeds of all are below 0.5 ms-1. The São Francisco river, in the transversal sections studied along its length, presents velocities between 3.09 ms-1 to 1.68 ms-1 for the period of flood and in the period of drought the speeds are between 0,44 ms-1 to 0,12 ms-1. In the Paraná River, velocities are between 2.17 ms-1 to 1.50 ms-1 and 0,59 ms-1 to 0,12 ms-1 for the greater and smaller flow, in due order. It was verified that the Amazon river has hydrokinetic potential that can be explored all year round. In the São Francisco basin, it is only in the period of higher flows that there is potential for the installation of hydrokinetic turbines, similar to the Paraná river basin. Of course, at points in rivers where there are hydroelectric plants, this assessment should change due to the dispatch of power plants.
Acesso aberto (Open Access)
Proposta de otimização de modelo de regionalização de curvas de permanência de vazões
(Universidade Federal do Pará, 2014-05-16) SILVA, Raimunda da Silva e; BLANCO, Claudio José Cavalcante; http://lattes.cnpq.br/8319326553139808
Due to lack of data flow in the State of Pará, the regionalization of streamflow duration curves, presents itself as an important technique, allowing the estimation of flow in sites with insufficient or no data. Hus, this paper aims to propose the optimization of a model of regionalization of streamflow retention curves for the Para region. The model was based on data at 43 gauged stations distributed in the state of Pará. The flow duration curves were calibrated using 5 regression models: power, exponential, logarithmic, quadratic and cubic. Regionalization model was established using the multiple regression technique. The spatial variation of each parameter was explained in terms of the drainage area, mean annual precipitation, length and slope of the main river. The model was validated using the Jack -knife procedure. The best fit of the cubic model was mathematically represented by the quadratic mean relative errors (ϵ%), coefficients of Nash-Sutcliffe (Nash) and the graphics settings the simulated and observed streamflow. The optimization model was achieved by insertion of synthetic stations and cluster stations by drainage area. The number of synthetic stations included in the model were evaluated by Root Mean Square Error (RMSE), the coefficient of Nash and the ϵ%. For groups I and II the optimal number of synthetic stations, who joined those already considered in the groups, it was 6 and 3, respectively. In group III only the clustering method in relation to drainage areas was sufficient for good performance of the regionalization model. The good performance of the calibrated, validated and optimized model demonstrated the potential of this in the estimation of retention curves of the rivers that cross the Para. The geographic coordinates of synthetic stations, which optimized the model can serve as a suggestion to the government where to install new stations. The number of new stations would be limited to the results of optimization, streamlining resources and building up the model developed to determine retention curves flow for the entire state of Para. In this case, the new installed stations, would also help in the future to improve the model performance.
Acesso aberto (Open Access)
Tide distortion and attenuation in an Amazonian tidal river
(2012-12) FREITAS, Paulo Tadeu Amorim; SILVEIRA, Odete Fátima Machado da; ASP NETO, Nils Edvin
The present study seeks to evaluate tidal propagation in the Guamá-Capim river system, in the Amazonian region, considering hydrodynamic and geomorphological aspects. Available data sets on fluvial discharge and water level variations were considered, besides several methods of measuring the tides (currents, water levels and discharges) recorded at different stations and in different periods. The main point argued is that fluvial discharge is the key-factor in tidal distortion and tidal bore formation in the system investigated, whereas the low relief of the area would be the main factor contributing to landward tidal incursion. The results show an impressive upward tidal incursion of more than 200 km, including substantial distortion -increasing upstream -of the tidal wave, of which the ebb phase lasts up to 5 hours longer than the flood, including higher flood current velocities as far as 161 km upstream. Generally, only hyposynchronous tidal response was observed. Seasonally, the fluvial discharge varies about 10 times in the Guamá and 4 times in the Capim River. The increase of the fluvial discharge results in an increasing distortion of the tide, besides a weak increase of the attenuation. During high fluvial discharge periods in conjunction with equinoctial tides (e.g. March-April), a tidal bore occurs in the system, also increased by the generally low relief. Therefore, the conclusions include: low relief and the distortion related to high fluvial discharges are the main factors controlling tidal propagation along the system and tidal bore formation. Furthermore, the system could be classified as a tidal river, in which massive regional fresh water input results in virtually non-existent salinity throughout the Guamá-Capim system.