Search

There has been an increasing number of global model studies that relate water quality to the watershed land use. The strategy of considering a model that is comparable to the Soil Conservation Service Curve-Number method that employs land use maps to estimate the effects of land use on the water quality, has considerable potential for application. In this context, this paper presents the LUPC (Land Use Pollutant Contribution) Model that relates pollutant loads originated by several types of coverage and a weight function which determines the load decay through water basin. It makes an estimate of the watershed features that are produced by conducting an analysis of the river profile, which is shown here in terms of the labile and refractory organic matter (OM), differentiated by its percentage of aromaticity. The initial results which were obtained by applying the model in a river basin located in the south of Brazil, suggest that the model can estimate the load of OM at a point of interest in the river and has proved to be a valuable tool for enabling managers to make decisions about the use planning land use and its impacts for water resources planning and management.

Limited water quality data is often responsible for incorrect model description and misleading interpretation in water resources planning and management scenarios. This study compares two hybrid strategies to convert discrete concentration data into continuous daily values for one year in different river sections. Model A is based on an autoregressive process, accounting for serial correlation, water quality historical characteristics (mean and standard deviation) and random variability; the second approach (model B) is a regression model, based on the relationship between monitoring flow and concentrations, plus an error term. The generated series (here referred to as synthetic series) are propagated in time and space by a full deterministic model (SihQual), that solves the Saint-Venant and advection-dispersion-reaction equations. Results reveal that both approaches are appropriate to reproduce the variability of biochemical oxygen demand and organic nitrogen concentrations, leading to the conclusion that the combination of deterministic/empirical and stochastic components are compatible. A second outcome arises from the comparison of results in different time scales, supporting the need for further assessment of statistical characteristics of water quality data - which relies on monitoring plans. Nonetheless, the proposed methods are suitable to estimate multiple scenarios of interest in water resources planning and management.

Wind variability and hydro-wind complementarity should be both considered in the planning of electrical power systems. In such cases, the spatio-temporal dependence between streamflow and wind speed regimes needs to be asses to balance the electricity generation. Medium-term hydrothermal scheduling problems (MTHS) are used to define operation policies for electrical power systems under 5–10 years horizon. MTHS uses stochastic optimization techniques fed by synthetic streamflow scenarios. To set better operation policies, such scenarios should well represent statistical features of historical data. With the rapid growth in the installed capacity of wind power, operators are encouraged to consider novel approaches to represent the dependence of hydrometeorological variables. This study integrates wind variability and hydro-wind complementarity in the medium-term planning of electrical power systems employing joint simulation of periodic streamflow and wind speed time series. The generated scenarios are used as input to derive monthly operational policies via Implicit Stochastic Optimization. A hydropower plant and a wind farm, both located in the Northeast region of Brazil were selected as a case study. Results show that considering wind variability and hydro-wind complementarity can significantly reduce energy deficits in power systems and increase the flexibility in the operation of water reservoirs.

This paper explores and combines implicit stochastic optimization (ISO) with copula functions to simulate long-term operating policies for a hydropower reservoir located in the Northeastern region of Brazil. Overall, ISO is considered as one of the most reliable techniques to derive long-term reservoir operating rules for reservoirs. This method employs a deterministic optimization model to estimate the optimal reservoir allocations under different inflow scenarios and later constructs operating rules for each month by relating the ensemble of the optimal releases, the initial storage volume and future inflow values. Those rules are generally established by fitting approaches including linear regression or nonlinear methods. This work illustrates the applicability to combine copulas with ISO to define reservoir operation policies based on a probabilistic procedure. Firstly, synthetic streamflow scenarios are simulated using a periodic vine copula model. Afterward, optimal release data are estimated by ISO for a set of inflow scenarios. Joint probability distribution functions based on copulas are constructed in order to forecast the expected release, conditioned to the initial reservoir volume and future inflows data. Results indicate that the proposed model represents a flexible approach to construct operating rules and derive long-term reservoir operating policies with low variability, allowing to reproduce different dependence structures of simulated data.

The watershed surface runoff was investigated through the one-dimensional numerical simulation using the Lattice Boltzmann Method (LBM). A computational model was developed where the watershed is represented by the junction of nine sub-basins. For this, two equilibrium distribution functions were established through the Chapman-Enskog Expansion on a D1Q5 lattice, one suitable for flow on the basin surface and another for the main channel, obtaining the water depth on the basin surface and the channels cross-sectional area. In addition, the boundary condition was established in the flow passage from one sub-basin to another, taking into account the mass conservation and, in order to obtain a simulation closer to reality, it was considered an initial river flow (baseflow) of each channel stretch. The numerical results obtained by the LBM were compared with data measured in field.

This work presents the numeric simulation of flow in a reservoir, using the finite volume method for solver the system of equations that model the two-dimensional flow in shallow water, neglecting the tangential tensions. The solution of the system of linearized equations was obtained by computational implementation of the Gauss-Seidel iterative method. To illustrate the application of the numerical scheme in hydraulic engineering, it was considered the study of flow in an underground reservoir with internal pillars, whose flow is generated by the opening of two outlet gates. The employed code allowed the temporal analysis of the volume and the flow in the reservoir, the graphical interpretation of the investigated physical phenomenon as well as, the calculation of the precision of the model. The results obtained show the expected physical interpretation, good agreement with literature data, good precision,stability and low computational cost.

Hydrodynamic modelling is an important tool for several studies, such as flood forecasting and analysis of energy and mass transport. In rivers, the most common calibration parameter is the roughness coefficient, that accounts for the friction term. However, while uncertainties are associated to this parameter definition, it is often defined as constant over time or space. Even though sophisticated techniques are available for model calibration, unsteady flow routing applications usually involve simplified methods, such as trial-and-error and Monte Carlo strategies. These practices can be subjective, time consuming and dependent on user experience; on the other hand, automatic approaches may generate unrealistic values and require large computational efforts. This study introduces a new strategy to calibrate one-dimensional hydrodynamic models, accounting for temporal and spatial variation while maintaining computational thrift. Among multiple random roughness coefficients, a time series is generated according to a linear relationship with observed water depths or flow for five control sections; the resulting daily series of parameters are the set for simulation inputs. The algorithm was combined with the hydrodynamic module in the SihQual model (Hydrodynamic and Water Quality Simulation); when compared to observed data, it showed to be suitable to predict discharges and water levels for different years over 85 km of the Iguacu river, located in Parana (Brazil). Compared to Monte Carlo and trial-and-error techniques for calibration, the HTC method (Hydrodynamic Temporal Calibration) was able to match their results or even improve simulations in some cases, requiring less user interaction than the other approaches. The study highlights the relevance of including a temporal component in model calibration, aiming to reduce the overall inherent uncertainty of this process.

The present study presents the results of research whose main objective was to use hydrological data on flow to verify the efficiency of the parameter curve number (CN) of rainwater retention in river basins on a regional scale, through multivariate statistical analysis, to contribute to the administration and management of water resources. The CN is part of the method of estimating flow used by the Soil Conservation Service (SCS). This rainfall-runoff model is used to estimate flow in small river basins, based on soil data and the evolution of land use and occupation. The method was applied to 14 hydrographic sub-basins - PR, whose confluences coincide with the gauging stations, to set up the sampling points for the multivariate statistical analysis of canonical correlation. The result of the canonical correlation, represented by the canonical R was equal to 0.90 with canonical R2 equal to 0.81, chi-square (χ2) of 15.8577 and DF (degrees of freedom) equal to 7, which is very significant and expresses a high correlation between the method and flow rates. These results confirm the hypothesis that the CN can be validated by the flow.

The present work develops a model of computer simulation of the actual properties of concrete under the action of alkali-silica reaction. Obtains a computational representation from the analysis of the chemical reaction and homogenenization techniques. Alkali-Silica reaction forms a gel that changes the effective properties of concrete and can lead to damage to structures, especially of hydroelectric dams. The model consists of three phases, generation of representative element of concrete, gel formation and dissemination by alkali-silica reaction and homogeneization of the final material. The first stage is the development of representative concrete element that is simulated from the granulometric curve and uses a computacional collision detection algorithm to ellipses. To model the behavior of chemical evolution, it uses a system based on equations of chemical kinetics, known as Guldberg - Waage Law and uses a gel diffusion model developed to mesh of representative element of concrete. To model the variation of the effective properties, it uses homogenization schemes (Reuss method, Voigt Method, Self-Consistent method and Mori-Tanaka method) to provide, thus, elasticity coefficientes of the composite material. The combination of the models allowed to predict the evolution and damage to the material over time and analyze the influence of the volume fraction of agregates in the lifetime of concrete.

Recent water resources planning and management strategies state that the concepts of risk and variable inputs should be appraised in order to comply with multiple conditions. This becomes evident especially in environments with diverse uses of water, land use and climate change. In such a context, modelling of discharges and concentrations in rivers are valuable strategies to predict different scenarios. This research proposes an integrated analysis for modelling of flow and contaminant transport in rivers, based on hydrodynamics, time series, and water quality simulations. The first module estimates water volume and velocity, that have direct impact in pollutants transport; time series of concentrations are generated as synthetic pollutographs, using techniques based on flow conditions, time and statistical factors of a historical monitoring dataset – the objective is to match temporal scales of boundary conditions, since water quality data is usually available as irregular samples; the third module solves the advection-dispersion-reaction equation, exploring the different synthetic series as input. Results evidence that the input pollutograph, usually not explored in similar studies, may have a significant role in simulations for transport of substance in rivers under unsteady state; as consequence, corroborate with better estimates for planning strategies where temporal dynamic is relevant. The contributions lay the basis for further assessment of riverine systems linked to watershed dynamics, with multiple scenarios of data availability and input conditions.

Este artigo propoe uma metodologia hibrida para a previsao das series temporais de deslocamentos relativos em um bloco da barragem da usina hidreletrica de Itaipu, que integra os seguintes metodos numericos: decomposicao wavelet , support vector Machine e combinacao linear de previsoes. Todos os resultados estatisticos alcancados pela metodologia proposta foram mais acurados do que outras tecnicas tradicionais (usadas aqui como benchmark ), encorajando a sua adocao para tal finalidade.

While advection, dispersion, and their hydraulic background are broadly explored in water quality modelling, conversion processes (reaction and decay rates) usually lack of attention. They represent physical, chemical and biological processes that reactive substances go through in contact with water, typically assumed as calibration parameters. This study introduces a method for model calibration considering a temporal aspect of transformation coefficients: TRATS – Transformation Rates Time Series. Daily decay rates are generated as result of: (i) attributes of the river station, (ii) reference values from literature, and (iii) random variability. These transformation parameters are then applied in water quality simulations under unsteady state in a river, for biochemical oxygen demand (BOD), organic nitrogen (N-org) and dissolved oxygen (DO). The proposed method for integrated modelling suggests that temporal variation of kinetic processes may play an import role in transport and fate of pollutants in terms of overall variability and attenuation over time and space, and this aspect can be included in the calibration phase.

Wind power energy has been showing significant growth in installed capacity around the world. This opportunity presents big challenges to operate power systems with high wind power penetration levels, considering the variability and intermittent behavior of this type of power source. To reduce uncertainties associated with this kind of power systems, researchers have explored the integration of wind power energy with other renewable energy sources, like solar and hydropower. For instance, the integration of wind and hydro systems can deal with the spatial and temporal complementarity of hydrological and wind regimes to produce energy. Therefore, it is necessary to consider the stochastic behavior and the dependence structures between these variables to define better operational policies. This study explores the spatial correlation of hydrological and wind regimes in different regions of Brazil and defines an entropy-copula-based model for the joint simulation of monthly streamflow and wind speed time series to evaluate the potential integration of hydro and wind energy sources. The proposed model showed a good adherence to the periodic behavior for both variables, and the results indicate that simulated scenarios preserved statistical features of historical data.

Derived from simplifications of the Saint-Venant equations, the kinematic wave model has the ability to describe the behavior of surface runoff in watersheds. This paper aims to obtain the numerical simulation of the flow routing in a natural watershed, by using lattice Boltzmann method. In the computational model, the surface of the basin will be represented by a V-shaped segmented in two lateral planes and one main channel. The simulation considers the effective precipitation flowing on the watershed per unit of width at the exit of each of the planes that represent the surface of the basin. The water flowing from the planes enters the main channel in the form of lateral contribution. Hydrograms of two rain events are obtained, which present the volume drained in the outlet corresponding to the whole basin in each event. Two equilibrium distribution functions were developed by Chapmann-Enskog expansion at time scales and model D1Q3, one suitable for flow on the basin surface and another for the main channel, in order to obtain the variables of interest in each case. The numerical results obtained were compared with the KINEROS2 hydrological model.

A two-dimensional numerical simulation of the water flow in a rectangular channel with submerged obstacles distributed alternately along its banks is presented. The governing equations of flow are the shallow water equations, which will be solved by the Boltzmann lattice method (LBM) with multiple relaxation times (MRT). The non-slip bounce-back scheme was used on walls and obstacles, constant discharge at the inlet and fixed depth at the outlet of the channel. Due to the characteristics of the problem to be simulated, a large eddy simulation (LES) technique was incorporated into the computational code, which allows to obtain results that are closer to the actual behavior of the flow. In addition, the stability of the simulation at all points of the mesh is evaluated for each step of time and, together with the property of the consistency of the LBM, the convergence of the solution is obtained. The simulation provides the depth, velocities in the x and y directions, and the magnitude of water vorticity.

This paper presents a new explicit scheme for the solution of shallow water equations in one and two space dimensions, developed from the space-time conservation element and solution element (CE/SE) method. The basis functions used are second-order Taylor expansions in time and space. This increase in the order of the approximation functions produces an increase in the number of unknowns in the scheme, therefore, besides the flow variables and their slopes, their second-order partial derivatives are also unknown in the present scheme. An iterative process for the calculation of the first and second order derivatives is formulated for problems with shocks and discontinuities. Computational experiments demonstrate third-order accuracy. The one-dimensional and two-dimensional dam-break problems presented validate the accuracy and robustness of this scheme.

The study of minimum flows is increasingly important due to the relationship with ecosystem sustainability, the economy and its role as a sentinel of climate change. The aim of this paper is to contribute to the theoretical treatment of minimum extremes and, specifically, minimum flows. The method has two approaches: i) conventional; ii) asymptotic. In conventional analysis, the Weibull (W2) and Lognormal distributions of two parameters (LN2) were adjusted to the series of annual minimum flows and minimum averages of 7-day flows. In the asymptotic analysis approach two parent distributions, the distributions of all average daily flows, with power behavior for minimum flows, are investigated: i) Gamma; ii) LN2. The theory studied in this paper is applied to 11 gauged stations in the Iguaçu river basin with 48-year data series. It was concluded that the LN2 distribution presents the best fit according to the χ 2 test. It was found that the Gamma distribution, with respect to the minimums, tends to a power function, and consequently the W2 distribution. The parameters k, b and μ X , of the normalized annual minimum flow series are well-fitted to the LN2 distribution. According to both approaches, LN2 can be recommended for studies of minimum flows in the Iguaçu river basin. RESUMO O estudo de vazões mínimas torna-se cada vez mais importante devido à relação com a sustentabilidade de ecossistemas, da economia e como sentinela das mudanças climáticas. O objetivo deste artigo é contribuir para o tratamento teórico sobre extremos mínimos e, especificamente, vazões mínimas. O método divide-se em duas abordagens: i) convencional; ii) assintótica. Na análise convencional foram ajustadas as distribuições de Weibull (W2) e Lognormal de dois parâmetros (LN2) às séries de vazões mínimas anuais e mínimas médias de 7 dias. Na análise assintótica duas distribuições “mãe”, distribuições de todas as vazões médias diárias, com comportamento de potência para vazões mínimas, foram investigadas: i) Gama; ii) LN2. O estudo foi aplicado a 11 estações fluviométricas da bacia hidrográfica do rio Iguaçu com 48 anos de dados. Concluiu-se que a distribuição LN2 apresentou melhor ajuste segundo o teste χ 2 . Verificou-se que a distribuição Gama, com relação aos mínimos, tende a uma função de potência, e em consequência à distribuição W2. Os parâmetros k, b e µX, das vazões mínimas anuais moduladas, ajustaram-se bem à distribuição LN2. De acordo com as duas abordagens utilizadas, pode-se recomendar a LN2 para estudos de vazões mínimas na bacia hidrográfica do rio Iguaçu.

This paper analyzes the ability of the Lattice Boltzmann method (LBM) with multiple relaxation times (MRT) in the simulation of flow in practical engineering problems. The case study covered refers to the first section of the initiation channel, which is part of the piracema channel, located in the Itaipu Hydroelectric Power Plant. The initiation channel has submerged obstacles distributed from one margin to the other, in order to reduce water velocity and allow the piracema cycle to occur. The governing equations of flow are the shallow water equations, which will be solved through the LBM-MRT. The non-slip bounce-back scheme was used on walls and obstacles, constant discharge at the inlet and fixed depth at the outlet of the channel. Due to the characteristics of the problem to be simulated, a large eddy simulation (LES) technique was incorporated into the computational code, which allows to obtain results that are closer to the actual behavior of the flow. In addition, the stability of the simulation at all points of the mesh is evaluated for each step of time and, together with the property of the consistency of the LBM, the convergence of the solution is obtained. The simulation provides the depth, velocities in the x and y directions, and the magnitude of water vorticity.

O metodo do reticulado de Boltzmann (LBM) possui equacao governante caracterizada pelas etapas de transmissao e colisao, e pode ser visto como uma forma discretizada da equacao cinetica de Boltzmann em que somente sao mantidos os detalhes moleculares essenciais para recuperar o comportamento macroscopico. O metodo e eficiente na simulacao de escoamento de fluidos, mostrando-se competitivo nas aplicacoes de mecanica dos fluidos computacional, sendo especialmente util em aplicacoes com geometrias complexas. O objetivo deste trabalho e utilizar o LBM para simular o escoamento de agua em um canal entre placas paralelas. Para isto, foram usadas condicoes de contorno bounce back e Zou-He. Fez-se a comparacao entre as solucoes numerica e analitica, para a validacao do metodo.

A teoria da homogeneizacao busca descrever as relacoes existentes entre as propriedades conhecidas em escalas menores daquelas que ocorrem em escalas maiores, permitindo a simulacao de materiais heterogeneos. Este artigo tem como objetivo apresentar uma simulacao computacional das propriedades do concreto utilizando tecnicas de homogeneizacao. Para construcao desta simulacao foram utilizadas propriedades pre-determinadas dos componentes do concreto. A simulacao construida e composta por duas fases: a argamassa e os agregados graudos. Tambem foram utilizadas como dados de entrada, informacoes obtidas pela curva granulometrica do material analisado. Para determinar os limites superior e inferior sao utilizados, respectivamente, o metodo de Voigt e Reuss, assim como o metodo auto-consistente e de Mori-Tanaka sao utilizados para determinar as propriedades efetivas. Os resultados encontrados permitem enfatizar a importancia dos limites superior e inferior como analise de dados para os metodos atuais.

Resumo. Este trabalho explora a estrutura de malhas uniformes, obtidas a partir de esquemas de diferencas finitas explicitos de equacoes hiperbolicas lineares, escalonadas por meio da relacao incremental c_t = _x. Seu objetivo e apresentar formas alternativas e eficientes de inclusao de condicoes iniciais e de contorno. Experimentos numericos sao realizados e comparacoes com tecnicas tradicionais de insercao sao apresentadas. Concluimos que as abordagens propostas favorecem a acuracia dos esquemas explicitos utilizados, sobretudo no que tange a malhas com baixo grau de refinamento. Palavras-chave: Razao de ouro, Erro de Truncamento Local, Condicao de Estabilidade, Curvas Caracteristicas

RESUMO Resultados de um estudo cujo objetivo geral foi verificar a eficiência, com dados hidrológicos de vazão, o parâmetro "curve number" (CN) de retenção de águas pluviais em bacias hidrográficas, na escala regional, através da análise estatística multivariada visando contribuir para a gestão e manejo dos recursos hídricos. O CN faz parte do método de estimativa de vazões do Soil Conservation Service (SCS), um modelo chuva-vazão que é utilizado para estimar vazões em pequenas bacias com base em dados pedológicas e de evolução de uso e ocupação do solo. O método foi aplicado em 14 sub-bacias hidrográficas - PR, cujo exutório coincidisse com as estações de coleta de vazão, visando compor os pontos amostrais para a análise estatística multivariada de correlação canônica. O resultado da correlação canônica, representada pelo R canônico foi igual a 0.90 com R2 canônico igual a 0.81, qui-quadrado (χ2) de 15.8577 e GL (graus de liberdade) igual a 7, o que é muito significativo e expressa alta correlação entre o método e as vazões. Estes resultados confirmam a hipótese de que o CN pode ser validado pela vazão. RESUMEN Los resultados de un estudio cuyo objetivo general fue verificar la eficiência, utilizando los datos de flujo hidrológicos, el parámetro "curve number" (CN) de retención de agua de lluvia en las cuencas hidrográficas, a escala regional, mediante un análisis estadístico multivariante, para contribuir a la gestión y manejo de los recursos hídricos. La CN es parte de la estimación de flujo del Soil Conservation Service (SCS), un modelo de precipitación-flujo que se utiliza para estimar los caudales en cuencas pequeñas con base en datos del suelo y evolución del uso y la ocupación. El método se aplicó a 14 sub-cuencas - PR, exutório que coincidió con la colección fluyen estaciones, Para componer los puntos de muestreo para el análisis multivariante de correlación canónica. El resultado de la correlación canónica representado por R canónica fue igual a 0,90 con R2 canónica igual a 0,81, chi-cuadrado (χ2) de 15.8577 y GL (grados de libertad) igual a 7, que es muy significativo y expresó alta correlación entre las tasas de método y de flujo. Estos resultados confirman la hipótesis de que la CN puede ser validada por el flujo. ABSTRACT The present study presents the results of research whose main objective was to use hydrological data on flow to verify the efficiency of the parameter curve number (CN) of rainwater retention in river basins on a regional scale, through multivariate statistical analysis, to contribute to the administration and management of water resources. The CN is part of the method of estimating flow used by the Soil Conservation Service (SCS). This rainfall-runoff model is used to estimate flow in small river basins, based on soil data and the evolution of land use and occupation. The method was applied to 14 hydrographic sub-basins - PR, whose confluences coincide with the gauging stations, to set up the sampling points for the multivariate statistical analysis of canonical correlation. The result of the canonical correlation, represented by the canonical R was equal to 0.90 with canonical R2 equal to 0.81, chi-square (χ2) of 15.8577 and DF (degrees of freedom) equal to 7, which is very significant and expresses a high correlation between the method and flow rates. These results confirm the hypothesis that the CN can be validated by the flow.

No presente trabalho são apresentados os resultados de um estudo cujo objetivo geral é analisar a evolução temporal do potencial de retenção de águas pluviais de bacias hidrográficas com base no parâmetro “Curve Number” (CN) do método de estimativa de vazões do Soil Conservation Service (SCS), visando contribuir para a gestão e manejo dos recursos hídricos. O método do SCS é um modelo chuva-vazão que é utilizado para estimar vazões em pequenas bacias com base em dados pedológicos e de evolução de uso e ocupação do solo. A cobertura do solo, derivada de imagens de satélite Landsat TM 5 foi usada para estimar o parâmetro CN e a evolução temporal deste parâmetro foi analisada para caracterizar as principais mudanças na área de estudo. O método foi aplicado na sub-bacia hidrográfica do rio Mourão de 854 km2, localizada no curso médio do rio Ivaí – PR. Comparando os dados para o ano de 1986 e 2011, obtiveram-se os seguintes resultados: 68% da área permaneceram com o mesmo valor de CN, seguido de 20% de aumento da impermeabilização e 12% de diminuição da mesma. Observou-se que a principal causa para o aumento da impermeabilização foi que a urbanização também aumentou em 7% em áreas de solos com restrições ao uso. Estes resultados explicam o aumento da vazão de 2011 em comparação a 1986, que foi na média de 8%, aliada também ao aumento da precipitação em 208,7 mm para o mesmo período. A B S T R A C T In this paper we present the results of a study aimed at the analysis of the temporal the evolution of the potential for stormwater retention in basins using the ";;;;;;Curve Number";;;;;; (CN) parameter of the Soil Conservation Service (SCS), run-off model. The SCS model is a run-off model that is used to estimate run-off in small watersheds using soil data and information about land use and land cover. Land cover was derived from satellite imagery and allowed to compute the CN parameter for each pixel. Comparing the values obtained for two different years, changes within the basin were analyzed. The method was tested using data of a 854 km2 sub-basin in the middle course of the Mourão river. The analysis lead yielded the following results: 68% of the area remained the same value CN, followed by a 20% increase and 12% of waterproofing decreases. It was observed that the main cause for the increase in urbanization that the sealing was also increased by 7% in areas with fragile soils. These results explain the increased flow rate of 2011 compared to 1986, which was on average 8%, combined with an increasing precipitation of 208.7 mm for the same period. Keywords: Temporal evolution, waterproofing, soil sealing.

This paper presents the modeling of a regional sewage treatment system as a non linear integer program. The model has a hydraulic module that verifies the viability of the proposed systems, and a second module that minimizes the construction and O&M costs of the system. The optimization of both modules is accomplished by the use of the simulated annealing metaheuristic

Rainfall–runoff models usually present good results, but parameter calibration sometimes is tedious and subjective, and in many cases it depends on additional data surveys in the field. An alternative to the conceptual models is provided by empirical models, which relate input and output by means of an arbitrary mathematical function that bears no direct relationship to the physical characteristics of the rainfall–runoff process. This category includes the artificial neural networks (ANNs), whose implementation is the main focus of this paper. This study evaluated the capacity of ANNs to model with accuracy the monthly rainfall–runoff process. The case study was performed in the Jangada River basin, Parana, Brazil. The results of the three ANNs that produced the best results were compared to those of a conceptual model at monthly time scale, IPHMEN. The ANNs presented the best results with highest correlation coefficients and Nash-Sutcliffe statistics and the smallest difference of volume. Citati...

A short-term discharge forecast model with 12-day horizon for the Salto Osorio Hydropower Plant basin is presented. The forecast is executed using the SMAP rainfall-discharge model and forecasted rainfall data from the ETA-CPTEC model. The model was developed using spatial interpolation routine to compute the average rainfall either observed or forecasted as well as the propagation and the back-propagation of discharges routines. The propagation times are computed by the cinematic wave technique. Considering the difficulty to assess the model response to different set of parameters, data lack of accuracy and the implementation of necessary simplifications, several versions of the proposed model were analyzed. Ten combinations of the model were studied based in distinct setups of calibration of the parameters and the basin humidity. The results of the versions of the model were then compared to the historical data observed during the 1996-2001 period and their adequacy, assessed. The validation of the model and analysis of the results were performed through visual examination of the hydrographs and statistical analysis. The version B-3 of the model the one that adjusts the superficial and underground reservoir states for the previous day and performs the calibration of the parameters after each simulation presented the best results. Key-words: streamflow forecast model, SMAP, Iguacu River

O aumento significativo no fluxo do trafego de veiculos tem causado diversos problemas para a sociedade. O estudo das caracteristicas do trafego de veiculos tem se tornado uma ferramenta importante para avaliar e planejar as rodovias. Nesse contexto, a simulacao computacional via automatos celulares pode ser utilizada como uma importante ferramenta para obtencao de caracteristicas fundamentais do trafego em rodovias ou em areas urbanas. Neste trabalho, desenvolveu-se um modelo de automatos celulares que utilizam regras simples de movimentacao dos veiculos, para analisar o tempo de escoamento de uma pista simples. A partir dos dados obtidos, formulou-se um modelo de regressao polinomial que relaciona o tempo medio total de escoamento e o numero de veiculos. Os resultados apresentados mostraram-se bastante satisfatorios e podem ser usados para desenvolver ferramentas de controle ou informacao sobre o trafego.

A equacao diferencial da linha elastica para uma viga em balanco, sujeita a uma carga pontual aplicada em sua extremidade e [...]

This paper presents a new approach for short-term hydro power scheduling of reservoirs using an algorithm-based Particle Swarm Optimization (PSO). PSO is a population-based algorithm designed to find good solutions to optimization problems, its characteristics have encouraged its adoption to tackle a variety of problems in different fields. In this paper the authors consider an optimization problem related to a daily scheduling of small hydro power dispatch. The goal is construct a feasible solution that maximize the cascade electricity production, following the environmental constraints and water balance. The paper proposes an improved Particle Swarm Optimization (PSO) algorithm, which takes advantage of simplicity and facility of implementation. The algorithm was successfully applied to the optimization of the daily schedule strategies of small hydro power plants, considering maximum water utilization and all constraints related to simultaneous water uses. Extensive computational tests and comparisons with other heuristics methods showed the effectiveness of the proposed approach.

A necessidade de modelar o fluxo de veículos tem se tornado uma prioridade nos grandes centros urbanos e vias de trânsito em geral. Esse tipo de modelagem pode ser usado como ferramenta para estabelecer novas estratégias, políticas de gerência e controle de tráfego para melhorar a eficiência do sistema de transportes. O tráfego de veículos pode ser representado fisicamente por três escalas: microscópica, macroscópica e cinética. Na modelagem matemática de sistemas físicos complexos, tais como o tráfego, nenhuma representação destas escalas é efetivamente consistente com a física do sistema analisado. Por outro lado, os autômatos celulares vêm se destacando entre os principais modelos computacionais para simulação do tráfego de veículos devido a sua capacidade de representar as principais características do tráfego, utilizando regras simples e baixo custo computacional. A diferença nesse tipo de modelagem é de não envolver nenhum tipo de equação. O principal objetivo deste trabalho é compreender o uso da modelagem computacional no estudo do tráfego de veículos por meio dos autômatos celulares. Isso é feito apresentando um modelo que emprega regras microscópicas na movimentação dos veículos em pista com uma faixa em sentido único. Os resultados obtidos são os gráficos da densidade vs. fluxo, conhecido como diagrama fundamental, e da densidade vs. velocidade The necessity to model the flow of vehicles has become a priority in large urban centers and transit routes in general. This type of modeling can be used as a tool to establish new strategies, policy management and traffic control, to improve efficiency in the transport system. The vehicle traffic can be physically represented by three scales: microscopic, kinetic and macroscospic. In mathematical modeling of complex systems, such as traffic, none of these scale representations is effectively consistent with the physics of the system analyzed. On the other hand, cellular automata are distinct among the main computational models for simulation of vehicular traffic due to its ability to represent the principal characteristics of the traffic by using simple rules and low computational cost. The difference is that this type of modeling does not involve any kind of equation. The main objective of this work is to understand the use of computational modeling in the study of vehicular traffic through cellular automata. This is done by presenting a model that employs microscopic rules on movement of vehicles on the track with a single one-way road. The results are expressed through by graphs, flow vs. density, known as the fundamental diagram, and density vs. velocity.