Luiz Emílio B. de Almeida

O Controle da Deriva Litorânea no Desenvolvimento do Campo de Dunas e da Antepraia no Litoral Médio do Rio Grande do Sul

Zones of erosion and accretion were delimited by comparing a DGPS shoreline mapping in 1997 and the beach line reproduced from the army chart collection of 1975. The results show extensive shore retreat along of Rio Grande do Sul central coast, while accretion was observed in Mostardas and Dunas Altas beach. Mathematical estimative of the regional longshore transport potential along the Rio Grande do Sul coast, a 630-km long holocenic fine sand barrier, resulted in a large net northward annual sand volume. Additionally, the estimated potential of sediment transport based on the CERC formula predicts a substantial variation of the energy flux into the surf zone, due to little changes in shoreline alignments and in the potential alongshore sediment transport. The reduction in the sediment flux due to changes in the shoreline alignment produce a jam in the longshore transport, meaning that part of the sediment arriving from the upstream stretch may be deposited or diverted offshore by coastal jet. Based on that, it is possible that changes in the net longshore sand transport are responsible for the increase in the shoreface width from less than 1 km to more than 3 km in Mostardas beach and Dunas Altas beach. Interesting to note that wider dune fields are associated to those beaches where shoreface is also wider. In this way, the volume of longshore sand transport and the sediment jam provide by changes on shoreline alignment in Mostardas and Dunas Altas beaches are important for both coastal dune fields and shoreface width.

On the wave energy potential along the southern coast of Brazil

The ocean wave energy resource is a real alternative to supply part of the energy demand in various countries, since some locations have a remarkable capacity to generate electricity. The objective of this study is to evaluate the energy resource of ocean waves in the coast of Rio Grande do Sul, the southern state of Brazil. This note presents the first results. The wave data used were collected in the sea area near the Port of Rio Grande during the years 1996 to 1999, amounting to sixteen months of monitoring. The data set was treated and grouped resulting information monthly, seasonal and annual basis. The annual average was found to be 8.6 kW per meter of wave front, reaching 14.0 kW per meter for the month of May and 4.0 kW per meter for the month of January. The results indicate good perspectives in obtaining power supplies. Copyright

Coastal Hydrodynamics and Longshore Transport of Sand on Cassino Beach and on Mar Grosso Beach, Southern Brazil

ABSTRACT Fontoura, J.A.S.; Almeida, L.E.; Calliari, L.J.; Cavalcanti, A.M.; Möller, O., Jr.; Romeu, M.A.R., and Christófaro, B.R., 2013. Coastal hydrodynamics and longshore transport of sand on Cassino Beach and on Mar Grosso Beach, southern Brazil. The hydrodynamic and morphodynamic parameters of a region in southern Brazil were determined by collecting sediments with stream traps (bedload and suspended load) in the surfzone and capturing images, studying topography, and researching sedimentology with the help of a movie camera, a total station, and laboratory work. Data on deep-water waves were garnered with a CPTEC/INPE model. Field work was carried out in 50 field trips during a 1-year period; 42 out of 50 trips focused exclusively on hydrodynamic and morphodynamic data, whereas eight of the trips were also used for collecting sediments. In addition, data on wind direction and velocity and on the longshore currents were also collected. All data were obtained in normal atmospheric conditions. Field work was carried out in six cross-shore profiles along Cassino Beach and Mar Grosso Beach (three profiles on each side of the estuary of Patos Lagoon).

Simulating an ocean wave power plant with Homer

In recent years, renewable resources have become an important alternative to increase the capacity of power generation. Among the resources available, the energy in the oceans have attracted more interest and experiencing a period of strong development. Wave energy is the one that is currently closest to reach a stage of technical and economic maturity. In this process, computational tools to facilitate evaluation of the feasibility of power systems including ocean wave power plants are critical. This paper presents the use of software Homer, version Legacy, for evaluation of technical and economic feasibility of hybrid energy systems including contribution of wave energy. Homer is a software designed for the optimization of micro power systems that has a very broad spectrum of applications. A case study in southern Brazil is presented, studying the inclusion of an ocean wave power plant in a wind biodiesel hybrid system and showing the functionality of Homer for this purpose. Copyright

Preliminary determination of the energy potential of ocean currents along the southern coast of Brazil

The ocean can be a strategic alternative for obtaining energy supplies, both from ocean waves as from sea currents and tides. Among these features, the power generation projects based on ocean currents are still under development. Generating energy from ocean can have great impact on the Brazilian energy grid, since Brazil has a vast coastline, with more than 9,000 km long, with potential for generating energy from ocean currents not fully estimated. This article presents a preliminary determination of the energy potential for power generation from ocean currents along the coast of Rio Grande do Sul, the southernmost state of Brazil, and also presents notes that contribute to the characterization of the system of ocean currents in the region. The data used were obtained in two areas near Tramandaí, allowing the determination of velocities and directions of the currents on a seasonal basis. The maximum speeds obtained rarely exceed 0.750 m/s, while the average speeds do not exceed 0.200 m/s. A relationship with the prevailing winds in the region was identified. Unfortunately, the results do not allow optimism about the power generation from ocean currents on the southern coast of Brazil, at least over the continental shelf. Copyright

Energetic Potential And Variability Of Ocean Currents On The Southern Coast Of Brazil

The energy in ocean currents has characteristics that make it one of the most important energy resources available and currently untapped. Thus, it is important to know the current systems and map the available energy resources. The Weibull distribution of two parameters was used to quantitatively describe the energetic potential and the system of ocean currents along the coast of Rio Grande do Sul, in the regions of Rio Grande and Tramandaí and the coast of Santa Catarina in southern Brazil. Based on the time series obtained for each region at different depths, the method of maximum likelihood in the velocity distribution, adjusting the scaling parameters (c) and form (k) of the model, were calculated. From these parameters, the values of average speed, maximum and minimum speed, standard deviation and coefficient of variation for each data set were calculated. The region of Rio Grande showed the highest average power density of 9 W/m2, while Tramandaí had the lowest values. The current velocities observed have low values for the utilization of this energy resource in the region.