Showing papers in "Revista Brasileira de Recursos Hídricos in 2001"
162 citations
TL;DR: In this article, a physically-based large-scale hydrological model is presented, which takes into account the distributed nature of the basin's characteristics such as land use, vegetation and stream network.
Abstract: The simulation showing transformation of rainfall into streamflow, and routing the generated flows through the streams in a basin, is widely used in many fields of water resources analysis, including understandSimulacao Hidrologica de Grandes Bacias 118 ing the earth surface phase processes of the hydrologic cycle. The early mathematical models developed to simulate this transformation were based on empirical relations between hydrological variables. The newgeneration hydrological models are physically based and distributed, and are adequate to represent small basins. There are few models able to simulate the hydrological processes in large basins, with an adequate physical base. In this paper we present a physically-based large-scale hydrological model, that takes into account the distributed nature of the basin’s characteristics such as land use, vegetation and stream network. The model was applied to two basins, almost 27.000 km2, with very distinct physical characteristics, and with many rainfall and streamflow gauging stations. The model performance, estimated by the fit between measured and calculated daily river discharges at different gauging stations, was very good. Applying the model enabled a preliminary analysis of land use changes in one of the basins, improving the understanding and comparison of the hydrological behavior of both basins. All results show that a large-scale hydrological model is a very useful tool in water resources analysis, even considering the data availability conditions in countries like Brazil. Key-words: simulation; rainfall-streamflow; large basins.
68 citations
TL;DR: In this paper, chemical analyses of major ions performed in some of the Pampasic ponds located in the lower reach the Salado River showed a similar composition to that of shallow groundwater, i.e., the total dissolved solids ranged be-tween 1 g/l and 2g/l, sodium was the most abundant among the cations and accounted for 80.6%.
Abstract: Chemical analyses of major ions performed in some of the Pampasic ponds located in the lower reach the Salado River showed a similar composition to that of shallow groundwater, i.e., the total dissolved solids ranged be-tween 1 g/l and 2 g/l, sodium was the most abundant among the cations and accounted (meq/l) for 80.6%. Calcium amounts were 6.5% while magnesium was 9.9%. Potassium was less abundant with a mean value of 3.0%. Apprecia-ble differences between summer and winter values were not observed. Since groundwater was the main source of surface water, a possible geochemical mechanism was proposed in order to achieve better understanding of the Pampasic pond’s water chemistry. The processes that seem to be responsi-ble for groundwater hydrochemistry are: cation exchange, ancient marine sediments dissolution and aluminosilicate weathering. The differences observed between surface water and shallow groundwater composition with respect to an addi-tional enrichment in sodium may be attributed to the evaporation-crystallisation process promoting calcite precipitation.
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TL;DR: In this article, the application of these instruments to the Pirapama River Basin in the Metropolitan Region of Recife (Brazil) is discussed. And the authors conclude that the joint use of such instruments may help both in the quantitative and qualitive management of water resources.
Abstract: Regulatory and economic instruments as mechanisms to support water resources management are discussed in this paper. The regulatory group studies the classification of water bodies according to their main uses, environmental licenses and the concession of water use rights. The economic group discusses charging for water use and markets for user and pollution rights. The paper studies the application of these instruments to Pirapama River Basin in the Metropolitan Region of Recife (Brazil). The study concludes that the joint use of such instruments may help both in the quantitative and qualitive management of water resources. However, it requires cooperation between environmental and water resources institutions in order to clearly define their legal and administrative functions.
8 citations
TL;DR: The integrated environmental management of river basins can be based on a multicriteria approach that establishes an ecology/economy equilibrium point and calculates the distance to an ideal point considered as a reference as mentioned in this paper.
Abstract: The integrated environmental management of river basins can be based on a multicriteria approach that establishes an ecology/economy equilibrium point and calculates the distance to an ideal point considered as a reference. This approach was applied to Cachoeiras River Basin, and the results show the optimal investments to reach a hypothetical equilibrium where the socio-economic and environmental aspects are equally important. Furthermore, it is concluded that ecological indicators (condition and stressors) needs to be considered if we really want to determine the environmental status and changes either due to stressors or management decisions. Key-words: menagement; integrated; basin.
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TL;DR: In this article, a study of the various alternatives to optimize water resources use and, consequently, minimize the problems associated with the scarcity of clean water, indicates that water should be reutilized in industries, agriculture and public supply.
Abstract: Although Brazil possesses 14% of all the freshwater on the Planet, water resources are scarce, in some regions, such as the states of São Paulo and Rio de Janeiro. In those regions, natural recharge of the aquifers is not sufficient to make up for groundwater used by industries, households and agriculture. The study of the various alternatives to optimize water resources use and, consequently, minimize the problems associated with the scarcity of clean water, indicates that water should be reutilized in industries, agriculture and public supply. Water reutilization is feasible, and this process is being developed in industries in the state of São Paulo, such as Kodak do Brasil, which is the subject of this paper.
TL;DR: As incertezas inerentes ao comportamento aleatório das vazões naturais consistem in uma das maiores dificuldades com que o processo de alocação de águas se defronta, agregando informação valiosa ao planejamento de recursos hídricos as mentioned in this paper.
Abstract: As incertezas inerentes ao comportamento aleatório das vazões naturais consistem em uma das maiores dificuldades com que o processo de alocação de águas se defronta. Tais incertezas não podem ser reduzidas, mas podem ser estudadas através de metodologias apropriadas, agregando informação valiosa ao planejamento de recursos hídricos. Entendendo que o estudo das incertezas é etapa fundamental para o gerenciamento dos riscos no processo de outorga, o presente trabalho analisa, fazendo uso de ferramentas da hidrologia estocástica, os efeitos do volume inicial, da variabilidade das vazões naturais, da capacidade de armazenamento e do nível de garantia nas estimativas das vazões regularizadas por um reservatório isolado. A análise abrange desde variabilidades características de rios de climas temperados (CV=0,2) até àquelas inerentes a rios do SemiÁrido (CV= 1,6). Como estudo de caso é utilizado Açude Caxitoré, localizado no Semi-Árido cearense; a validade do trabalho, no entanto, não se restringe unicamente ao local citado, uma vez que buscou-se o caráter geral ao adotar-se diferentes valores de capacidades para o reservatório e diferentes distribuições temporais dos influxos, estas últimas refletidas pelos diferentes coeficientes de variação assumidos para as vazões anuais, conservadas a média e a distribuição de probabilidades Observa-se que reservatórios com influxos de alta variabilidade são muito sensíveis às condições iniciais assumidas na simulação.
TL;DR: In this paper, a numerical technique is presented based on the construction of a calibration model, which allows the automatic determination of the best values for the nodal discharge demands and pipeline parameters.
Abstract: Operational models are very important to optimize urban water distribution systems in terms of minimizing electrical energy expenditures as well as to maximize required water supply satisfaction with adequate pressure level at all points of the city. However, in most Brazilian cities, water distribution systems are operated without using mathematical models; in part due to lack of knowledge and operator training practices, but mainly because there are difficulties in obtaining a calibrated mathematical model which captures the most important aspects of the hydraulic dynamics of the system. The calibration of a hydraulic model is usually a very difficult task because nodal discharge demands and hydraulic pipeline parameters values are very difficult to estimate properly. In this paper a numerical technique is presented based on the construction of a calibration model, which allows the automatic determination of the best values for the nodal discharge demands and pipeline parameters. The proposed model consists of a hydraulic network calculation algorithm and an optimization technique based on a search process to obtain the best values for the decision variables that minimize an objective function. The objective function is formed by summing up the differences in values between observed and simulated nodal pressure and/or pipe discharge. By using a relatively simple network example several numerical tests demonstrated the ability of the calibration model to determine the best values for the nodal discharge demands, friction coefficients and effective diameter of pipelines. Key-words: distribution system; hydraulic; model.
TL;DR: In this article, the uncertainties of temporal distribution of precipitation and parameters of the IPH II model were analyzed in estimating the design hydrograph, which was applied to a 40 km2 urban basin in Porto Alegre for two scenarios of urban development for which there were observed data: 19781982 and 1995-1997.
Abstract: The maximum design streamflow can be estimated based on a series of historical streamflows or a precipitation series and its transformation into flow by hydrological models of the rainfall-runoff type. There are few long, stationary flow series available for urban basins. Since the rainfall data are more plentiful, and present longer series, the latter method is more widely used in practice. This, however, generates uncertainties in the response due to: (a) difficulty in evaluating temporal and RBRH Revista Brasileira de Recursos Hídricos Volume 6 n.1 Jan/Mar 2001, 29-41 41 spatial distribution of rainfall: (b) variability of model parameters according to the basin and initial conditions; (c) and imperfections in the structure of the hydrological model. Thus the risk of precipitation is not the same as the risk of flow generated by the model. In this study, the uncertainties of temporal distribution of precipitation and parameters of the IPH II model are analyzed in estimating the design hydrograph. When using the value of maximum streamflow or volume in defining or sizing, the designer will base his work not on an uncertain point value, but on a confidence interval, with the expected value, which is an estimate of the uncertainties found. The method was applied to a 40 km2 urban basin in Porto Alegre for two scenarios of urban development for which there were observed data: 19781982 and 1995-1997. The results showed that the confidence interval is significant, as a result of all the uncertainties identified, but provides a reasonable estimate of the design flow as compared with the data observed for partial series of maximum flow. Key-words: design hydrograph; uncertainty; urban.
TL;DR: In this paper, a system for monitoring the climate ondulatório ao largo da costa da cidade de Rio Grande (RS), foi instalado, em convênio com o INPH, an ondógrafo direcional tipo waverider, at a batimétrica de 15 metros, a aproximadamente 15 quilômetros da linha da cost a.
Abstract: Com o objetivo de monitorar o clima ondulatório ao largo da costa da cidade de Rio Grande (RS), foi instalado, em convênio com o INPH, um ondógrafo direcional tipo waverider, na batimétrica de 15 metros, a aproximadamente 15 quilômetros da linha da costa. A fim de proporcionar uma melhor visualização dos dados registrados pelo equipamento e objetivando um estudo mais aplicado, foi desenvolvido um programa de computador de animação de espectros direcionais de ondas. Tal programa, através de uma interface amigável, torna mais fácil o acompanhamento da evolução da agitação marítima local. A entrada de dados do sistema consiste nos arquivos que são gerados pelo receptor do ondógrafo e a saída é representada por uma animação em três dimensões correspondentes a direção, freqüência e energia das ondas; existindo ainda a possibilidade de gerar arquivos com formato especial para posterior importação por um programa de planilha eletrônica. Consegue-se, então, uma ótima base para estudos relacionados principalmente à ocorrência de ondas de tempestade, geradas normalmente nas baixas latitudes do Atlântico Sul e associadas a entrada de frentes frias. Palavras-chave: dinâmica costeira; animação de espectros.
TL;DR: In this paper, the wave refraction analysis for a coastal site requires the construction of many refraction diagrams, one for each combination of wave period, height and deepwater direction of interest.
Abstract: Wave refraction analysis for a coastal site requires the construction of many refraction diagrams, one for each combination of wave period, height and deepwater direction of interest. The development of techniques for the numerical calculation of wave refraction diagrams in regions with uneven bottoms, as encountered in coastal areas, is a useful tool for Coastal Engineering studies. For this purpose, the mathematical and computation method to calculate the monochromatic wave refraction, proposed a few years ago by Dr. Alberto dos Santos (Franco, 1984), was improved, based on the method presented by Albernethy and Gilbert (1975). More information was added to the original program regarding wave deformations, such as the inclusion of the Theory of the Solitary Wave in the processes of velocity calculation, shoaling effect and breaking waves. The result of this process enables the visualization of the breaking zone for each wave and its characteristic parameters such as nearshore wave height and crest orientation at a given location. Moreover, the association of the wave crests with the orthogonals constitutes an excellent instrument to compare the plans of the theoretical crests with the real crests, for example, in aerial photographs. Quantification of these effects is also important to predict the longshore sediment transport. The development obtained has been applied in a case study describing the undulatory climate of the coastal area of Itanhaém (State of São Paulo), seeking to improve navigation in the Itanhaém River Bar. Key-words: wave; routing; coastal.
TL;DR: In this paper, the TCEV regionalization model is applied to the São Francisco river basin in the State of Minas Gerais, Brazil, where the available data on maximum precipitation and floods are not uniformly distributed in the area but both present good quality.
Abstract: The TCEV regionalization model is applied to the São Francisco river basin in the State of Minas Gerais, Brazil. This is the case of a big watershed where the available data on maximum precipitation and floods are not uniformly distributed in the area but both present good quality. Therefore, there is heterogeneity of the available hydrometeorological information about the watershed, in both time and space. This statistical model is based on the product of two exponentials, both occurring according to a Poisson process: the first corresponds to the most frequently observed events and the other corresponds to the outliers. After applying this model, two homogeneous regions were identified, dividing the river basin into south and north, for both annual maximum precipitation and annual maximum floods. These regions were confirmed by sampling analysis and by comparison with the L-moments regionalization methodology. In the case of the maximum precipitation, the definition of the homogeneous regions reflects the available physiographic and climatological information on the watershed. Key-words: maximun flood; homogeneous region; precipitation.