At the present time, the role of renewable energy in Brazil is significant as hydropower and other renewable energies, principally biomass, contribute 76.9 and 6.0 %, respectively, towards the total offer of electricity, as compared to the corresponding values of 15.8 and 2.8 % worldwide. Nevertheless, there is already an increasing role which is played by wind energy, and a promising potential for the exploitation of tidal current energy. This paper is concerned with the assessment of the tidal current resource in São Marcos Bay, which is located at the northeastern coast of Brazil, and which possesses a highly promising potential for the generation of electricity through the conversion of tidal current energy. Three potential zones for tidal power exploitation have been identified employing a two-dimensional (2DH) hydrodynamic model. Power densities for these regions are in the range of 9.2–11.2 MWh/m\(^{2}\)-year. Three array densities for two thrust coefficient values have been studied in each zone to evaluate hydrodynamic interferences, revealing positive as well as negative impacts regarding power density.

A investigação de processos inerentes a um sistema estuarino permite inferir de forma mais precisa sua complexa dinâmica, possibilitando o balizamento de estratégias de ação em planos de gestão e projetos ambientais em regiões costeiras. Este trabalho apresenta um estudo da hidrodinâmica do Sistema Estuarino de Santos (SP), com enfoque na análise da renovação de suas águas, pelo efeito da maré e pelas vazões fluviais afluentes. Por meio do SisBaHiA® (Sistema Base de Hidrodinâmica Ambiental) foi implementado um modelo hidrodinâmico computacional para a reprodução dos padrões de circulação do sistema. A partir de simulações com o Modelo de Transporte Euleriano, foram então calculadas as taxas de renovação de suas águas, para os períodos representativos de verão e de inverno. Os resultados, apresentados na forma de mapas e na forma de séries temporais de renovação, indicaram que após 30 dias todo o sistema apresenta uma renovação total maior que 95%. Diferenças sazonais puderam ser verificadas apenas em regiões mais internas do estuário, e.g., no Canal de Piaçaguera.

This study analyzes hydrodynamic aspects of the Guabanara Bay estuarine system, which is in the southern coast of the state of Rio de Janeiro, Brazil. Hydrodynamic circulation patterns were characterized, with and without the influence of baroclinic pressure gradients due to water density differences. Typical summer and winter scenarios are considered. The evaluation adopted computational simulations of hydrodynamic circulation, using models from the environmental hydrodynamic base system, entitled SisBaHiA. The simulations indicate that by disregarding baroclinic effects in the pressure gradients, the mean water levels in the Guanabara Bay are underestimated up to 5 centimeters, depending on the region and season of year. However, the hydrodynamic circulation patterns with or without baroclinic pressure gradients are very similar, as shown by the circulation patterns maps in different tidal phases.

The dynamics of cohesive sediments in natural water bodies is of great importance for coastal engineering. Quite often, it is necessary to assess sedimentological processes in regions where cohesive sediments are prevalent, such as in many harbors. Such assessments poses challenges, especially in quantitative evaluations, as the physics involved in the transport, sedimentation and erosion of cohesive sediments is rather complex. For that, by all means, it is important to have analysis tools capable of computing cohesive sediments dynamics. This paper presents the development of a vertically averaged eulerian transport model for suspended cohesive sediments. Such model is currently available on SisBaHiA®, which is a computational modeling system developed and maintained in COPPE/UFRJ. After describing the model implementation, we present a discussion on consistency and validation tests, for each implemented mechanism within the sedimentological process, with a focus in the erosion and sedimentation fluxes. In sequence, we compare model results with the theoretical results and, for some tests, with the results of the simulations performed with the Delft3D® and Telemac® modeling systems. These models are similar to the one presented in this paper, and are well accepted and widely used on professional projects and studies. The tests showed that the developed model results were consistent for all the evaluated mechanism, and hence it’s positively verified.

Araruama is a perennial hypersaline lagoon where seawater flows in through a narrow connection and spreads, where it is intensively evaporated. Although the inflow of seawater increases the salts load, a high inflow may reduce flushing time, decreasing salinity. Although reducing flushing time would improve water quality, the accompanying reduction in the salinity may change the ecological equilibrium. In the present research, a numeric hydrodynamic model was applied to Araruama Lagoon, to determine the maximum connection depth that promotes reduction of flushing time, however maintaining salinity. Five scenarios were executed in the hydrodynamic model SisBaHiA^© with changing hydraulic area, including channel average depths of 2.5 m, 3.0 m, and 4.0 m. The salinity simulations outlined three segmented sectors, the first associated with the connection channel, but also affecting the proximal portion of the lagoon; the second is an intense evaporation area, with high salinity values, and the third, in the western portion of the lagoon where freshwater inputs can affect salinity. The tested channel bathymetry scenarios promoted a salinity increase with a channel depth of 3.0 meters. With a connection channel depth of 4.0 meters (highest hydraulic area), the threshold limit is attained, and salinities are reduced in the lagoon.

This work applied the coupled horizontal two-dimensional hydrodynamic circulation model (2DH) and the vertically integrated water quality model for non-conservative and passive scalars to the Rio Verde reservoir in the state of Paraná, Brazil, to simulate flow, temperature and water quality parameters. The water quality model uses the same spatial grid applied for the hydrodynamics model. Flow velocities and turbulence coefficients previously defined in the hydrodynamics model can be used directly in the water quality model. Modeling results were compared to field data for a period of 308 days, from February 27th 2010 and December 31th 2010. Field data included water and air temperature, wind, relative humidity, radiation, discharges and concentration values of some substances in the tributaries of the reservoir. The results indicated that hydrodynamic circulation and, consequently, horizontal transport, are strongly dependent on the wind. Inflows/outflows generated a localized circulation. The results for the temperature and dissolved oxygen concentration were compared with field measures and a satisfactory consistency was achieved. Despite the errors associated with boundary conditions, the models demonstrated their potential to adequately simulate the data set collected from the reservoir.