Pedro Paulo Gomes Watts Rodrigues

Assessment of dispersion mechanisms in rivers by means of an inverse problem approach

In the present work the dispersion mechanisms in rivers are studied. The related direct and inverse problems are formulated and solved. The direct problem is solved by the finite volume method and the inverse problem by the Levenberg–Marquardt method.

Evaluation of dispersion parameters for River São Pedro, Brazil, by the simulated annealing method

The dispersion coefficient parameterizes different and complex phenomena that control substance transport in water bodies. This article presents an inverse problem approach solved by the simulated annealing (SA) algorithm to estimate dispersion coefficient and other parameters that can model dispersion in rivers with non-uniform geometry. The method is compared with two other classical methods, the peak concentration and Chatwin. The SA algorithm, peak and Chatwin methods were applied to the advection–dispersion model, whereas the SA was tested in the dispersion dead zone model (DDZM) as well. The methods are assessed in the study of a tracer transport achieved in a small mountain river. Comparing with observations, the best performance was obtained conjugating SA and the DDZM. The classical methods showed high sensitivity to the river discharge determination method, being more precise when the sections method was adopted. Considering this restriction, the inverse problem formulation solved by the SA approach showed to be a promising alternative, given that it can be built in a way that the river discharge itself can be estimated.

Utilização de Sistemas de Informações Geográficas na delimitação de bacias hidrográficas

This paper presents the determination of the drainage network of the city of Nova Friburgo-RJ, as well as the delineation of watersheds that are under its territory, among them the Bengalas river basin, which covers the most urbanized area of the city. The platform was used MOHID and used topographic data provided by the IBGE and municipal government. In order to verify the reliability of the results, they were compared with the ArcGIS software, renowned worldwide. We conclude that there is a strong possibility of using MOHID to analyze the profile of the flow of the Bengalas river basin and its tributaries.

Use of the MOHID Platform for computational simulation of oil ocean drift in the Campos basin - RJ

This work presents a model for ocean drift simulations data obtained with the MOHID software in the Campos Basin (RJ, Brazil) to study oil environmental issues. Results were compared with satellite data, as well as temperature and salinity data obtained by ARGO drifters available in the region.

Transformação Integral e Problemas Inversos aplicados à Estimativa de Parâmetros em um Modelo 2D de Transporte de Sedimentos Não-Coesivos

Neste trabalho apresenta-se uma abordagem de solucao hibrida analitico-numerica com a Tecnica da Transformada Integral Generalizada (GITT) para solucao de um problema bidimensional transiente do transporte de sedimentos nao-coesivos. Foram aplicados filtros analiticos para homogeneizar os contornos e melhorar a convergencia. A equacao foi transformada em um sistema acoplado de equacoes diferenciais parciais unidimensional que foi resolvido numericamente empregando recursos do Software Wolfram Mathematicar 10. Os resultados obtidos pela GITT se mostraram coerentes e apresentaram ganhos computacionais, o que e desejavel para a solucao do problema inverso de identificacao de parâmetros hidrodinâmicos e de transporte, utilizando o metodo de Monte Carlo via Cadeias de Markov.

Comparison of data mining models applied to a surface meteorological station

This paper presents the application of data mining techniques for pattern identification obtained from the analysis of meteorological variables and their correlation with the occurrence of intense rainfall. The used data were collected between 2008 and 2012 by the surface meteorological station of the Polytechnic Institute of Rio de Janeiro State University, located in Nova Friburgo RJ, Brazil. The main objective is the automatic prediction related to extreme precipitation events surrounding the meteorological station location one hour prior its occurrence. Classification models were developed based on decision trees and artificial neural networks. The steps of consistency analysis, treatment and data conversion, as well as the computational models used are described, and some metrics are compared in order to identify their effectiveness. The results obtained for the most accurate model presented a rate of 82. 9% of hits related to the prediction of rainfall equal to or greater than 10 mm h-1 one hour prior its occurrence. The results indicate the possibility of using this work to predict risk events in the study region.

DISPOSAL OF WASTE FROM CEMENTING OPERATION FROM OFFSHORE OIL AND GAS WELLS BUILDING

This paper presents computer modeling applied to the disposal simulation residual volume from offshore cementing unit, where the cement paste used by cementing operations of oil and gas wells. The software used was MOHID WATER with a lagrangian approach where the solid part of the residue was represented by conservative particles. It is able to assess the behavior of the solid part of the residue in the water column and its accommodation on the seabed. Future works using the Life Cycle Impact Assessment (LCIA) standard methods are considered to understand the results and the possible resulting harm to marine organisms.

ASSESSMENT OF THE IMPACT OF A SMALL HYDROELECTRIC POWER PLANT OVER THE WATER QUALITY OF THE ITABAPOANA RIVER THROUGH A COMPUTATIONAL MODEL

This work presents the results of hydrodynamic and transport, which were applied to a stretch of Itabapoana River, located in the northwest of Rio de Janeiro State, in order to assess the environmental consequences of the implantation of a Small Hydroelectric Plant. The models were calibrated by comparing simulated and observed data, for a giving condition, regarding both hydrodynamic and water quality variables. Once calibrated, the models simulated different scenarios, with a special emphasis to those generated under low flow regime, which are environmentally more critics. The results showed that, for these conditions, some water quality parameters, markedly the Dissolved Oxygen concentration, would be affected by the change in flow regime, caused by the withdrawal of water to power the turbines of the hydroelectric plant.

Análise do Processo de Infiltração de Água na Bacia do Rio Cônego com Base na Plataforma MOHID e suas Diferentes Formulações

O presente trabalho traz a simulacao do escoamento e infiltracao da agua oriunda de eventos de precipitacao ocorridos na bacia do rio Conego, localizada no municipio de Nova Friburgo, estado do Rio de Janeiro. O modelo bidimensional foi obtido atraves do sistema MOHID, tendo como base dados topograficos oriundos do Instituto Brasileiro de Geografia e Estatistica (IBGE) e disponibilizados pela Prefeitura Municipal de Nova Friburgo. Foram utilizadas as formulacoes explicita e implicita, bem como as diferentes simplificacoes das equacoes de Saint Venant durante as simulacoes realizadas. Os resultados obtidos se mostraram satisfatorios e convergentes. Pode-se concluir que o sistema MOHID representou bem a rede de drenagem assim como o processo de infiltracao e o perfil de escoamento da bacia do rio Conego.

Simulação Computacional do Transporte Horizontal Bidimensional de Contaminantes no Rio Macaé Através da Técnica da Transformada Integral Generalizada

Neste trabalho foi desenvolvida uma solucao hibrida analitico-numerica atraves da Tecnica da Transformada Integral Generalizada (GITT) empregando-se recursos de programacao simbolica atraves do Software Wolfram Mathematica 10, para solucao de um problema bidimensional transiente de dispersao de contaminantes em corpos d’ agua. Para tal, foi realizada a simulacao do comportamento do lancamento instantâneo de um contaminante conservativo (NaCl) em um trecho situado na parte inferior do rio Macae, localizado no nordeste do Estado do Rio de Janeiro. Para melhor convergencia da solucao hibrida foram aplicados filtros analiticos para homogeneizar os contornos, e consequentemente, a equacao transformada em um sistema acoplado de equacoes diferenciais parciais unidimensional, resolvido numericamente atraves de rotinas intrisecas do Mathematica. Os resultados foram comparados com dados experimentais disponiveis, e os resultados obtidos indicam a plausibilidade da solucao deste problema atraves do GITT, o que pode levar a ganhos computacionais, importantes para aplicacao em problemas inversos em trabalhos futuros.