Showing papers in "Revista Brasileira de Recursos Hídricos in 1998"

Análise Regional de Freqüência e Distribuição Temporal das Tempestades na Região Metropolitana de Belo Horizonte - RMBH

Abstract: This paper describes a L-moment-based methodology for the regional frequency analysis of heavy storms. The proposed methodology has been successfully applied to derive an IDF-type curve for the Metropolitan Region of Belo Horizonte MRBH. In addition, this paper describes a set of procedures to construct regional hyetographs to represent the time distribution of precipitation volumes over a given area. Its application to the MRBH is also presented.

Estimativa dos Parâmetros do Modelo IPH II para algumas Bacias Urbanas Brasileiras

Abstract: Rainfall – runoff models have often been used to evaluate the design hydrograph in urban basins due to the lack of recorded data and changes in basin characteristics. The hydrologic model IPH II has been used by many water resources professionals to estimate the flood hydrograph in urban basins. However, the main difficulty in applying this model is estimating parameters for different scenarios. In this study floods events from 28 urban basins in 6 Brazilians cities were used. The model parameters were fitted to these basins using the floods events and basin characteristics. The analysis of forecasts and parameter variability for these basins helped guide for use of this model in other urban basins.

Outorga para uso dos recursos hídricos: aspectos práticos e conceituais para o estabelecimento de um sistema informatizado

Abstract: Management of water resources requires a viable information system. This system is important because it provides a basis for procedures authorizing permits for water use: now a responsibility of the State since, according to the most recent Federal Constitution, all waters fall within its domain. This paper describes a strategy for granting permits for water use which takes account of current scarcity of flow data. The objective strategy relates water availability to demand, based upon research already available, namely (1) hydrological studies which make fullest possible use of available hydrometeorological information, and (2) surveys of present users of water resources for abstraction or waste disposal. The strategy takes for its starting point the existing relation between water available for use and the register of users determined by field survey. A new permit for water use reduces the available resource, assuming such a reduction possible, while suppression of a use by non-renewal of a permit increases the available resource. The information system reported here develops the permit-granting process by combining point data into a spatially-oriented framework, together with thematic maps of how water use is distributed regionally. Nota da edição: o custo dos artigos impressos a cores é de responsabilidade do autor.

Avaliação de Métodos para Dimensionamento da Irrigação Suplementar em Clima Úmido

Abstract: Supplemental irrigation has been recommended in wet regions as a way of reducing the risk of water deficiency, although there are no design criteria for irrigation systems applied to these regions, therefore the same criteria developed for arid regions have been adopted. In this study, the effective rainfall values obtained from the American Soil Conservation Service and the hourly and daily water balance models were compared with the values of probable or dependent rainfall. Different design criteria were applied to the meteorological data from Urussanga Station, in the brazilian state of Santa Catarina, l (28,31o S, 49,19o W, altitude 48,2 m).The results, led to the conclusion that the average monthly effective rainfall, estimated by SCS methods, shows values higher than those obtained from the daily and hourly water balance models. The inclusion of the Curve Number method in the daily water balance does not lead to any difference in effective rainfall for soils with a CN ranging from 60 to 90. The criterion for dimensioning the irrigation project using the difference between the average evapotranspiration and the probable rainfall, underestimates the needs for irrigation requirement.

Estimação Conjunta dos Parâmetros de um Modelo Estocástico Multivariado Contemporâneo Periódico Auto-Regressivo - PAR(P)

Abstract: Linear procedures based on SURE – “Seemingly Unrelated Regression Equations” are proposed in the paper, in order to obtain the Multivariate Contemporaneous Periodic Autoregressive – PAR(p) – joint parameters estimation of a stochastic model for synthetic hydrological scenarios.

Método Perturbativo Diferencial para Análise de Sensibilidade de um Modelo de Transferência de Soluto em Solos

Abstract: Total solute variations in the soil profile as a function of time and sensitivity analysis were calculated using both perturbation and transfer of soil solute models. Numerical solutions were performed, considering two values of apparent flow velocity of the soil solution and soil dispersivity as an input parameter. The results showed the viability of using perturbative methods for sensitivity analysis of solute dynamics in soils for values of velocities lower than 13,9 x 10 m/s.