Navegando por Autor "Antiqueira, Jose Antonio Fonseca de"

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Características sedimentares da desembocadura da Laguna dos Patos
(2005) Antiqueira, Jose Antonio Fonseca de; Calliari, Lauro Júlio
A porção inferior da Laguna dos Patos, um estuário micromaré é caracterizda por eventos de enchente e vazante regidos respectivamente por marés meteorológicas e pela descarga lagunar proveniente da bacia de drenagem. Com base em 179 amostras sedimentares, seis tipos de fundo foram identificados. Sedimentos arenosos encontram-se em áreas rasas adjacentes ao esporão arenoso gerado pelo transporte litorâneo induzido pela ação de ondas provindas do quadrante sul. Atrás do esporão, a existência de baixas condições hidrodinâmicas propicia a deposição de sedimentos finos representados por silte-argiloso, areia argilosa, um fundo misto e argila síltica. Com o aumento da profundidade, a quantidade de sedimentos finos aumenta. Devido ao complexo comportamento hidrodinâmico, um aumento no gradiente granulométrico transversalmente ao inlet a semelhança dos padrões descritos para os canais estuarinos localizados na porção média e superior do estuário inexistem. A falta do fundo areno-síltico é notável e provavelmente indique que os padrões sedimentares do inlet são dominados por correntes bi-direcionais. O padrão longitudinal indica a existência na porção norte do inlet de uma área síltico-argilosa, interpretada como sendo resultado do aprisionamento sedimentar causado pela excursão média da cunha salina a qual também controla os tipos de fundo mutáveis localizados mais ao sul. Os padrões aqui descritos podem representar situações efêmeras associadas a um regime hidrodinâmico predominantemente anual uma vez que durante o período amostrado, o fluxo de vazante atingiu 10.000 m³s¹. A falta de fundo arenoso proveniente de fonte marinha no extremo sul indica que essa observação é fundamentada.
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Determinação dos coeficientes de difusão turbulenta para a região do Porto de Rio Grande, RS, Brasil
(2005) Fontoura, Jose Antonio Scotti; Niencheski, Luis Felipe Hax; Antiqueira, Jose Antonio Fonseca de
This work presents a study on the horizontal turbulent eddy diffusion for both inner part and shallow areas around of Rio Grande Harbor navigation channel, Patos Lagoon estuary, RS, Brazil. It was made through the monitoring of Rodamine ‘B’ dyeusing aerial photos and water samples. From the radiometric interpretation of aerial photos in concomitance with tracer concentration level measured on environment was determined two different diffusion modes, one into the navigation channel dominated by strong currents and other on shallow areas in agree with weak local hydrodynamics. The mean horizontal turbulent eddy diffusion (K) determined for whole event was about 10065 cm²/s. Into the channel was identified a crescent diffusion rate with relation to the diffusion time and advection length, meanwhile in shallow areas was identified one decelerated process. The same was observed to the along flow eddy diffusion (Kx) and cross flow eddy diffusion (Ky). It’s also verified which the longitudinal eddy diffusion (Kx) varied from two to three times higher than transversal eddy diffusion (Ky) all process long. In shallow areas was also identified a eceleration on ratio between Kx and Ky. This behavior suggests one more important dispersion process into the channel when compared with the marginal areas.
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Evolução geomorfológica de um esporão arenoso na desembocadura da Laguna dos Patos, RS, Brasil – resultado de 85 anos de monitoramento
(2003) Antiqueira, Jose Antonio Fonseca de; Calliari, Lauro Júlio; Fontoura, Jose Antonio Scotti
No estuário da Laguna dos Patos, os padrões de circulação são dirigidos principalmente pelo vento e pela descarga de água doce. A direção do vento influencia os padrões de circulação local. Sob ventos de NE o gradiente de pressão aumenta e a retração das águas costeiras favorece a descarga lagunar. Contrariamente, ventos de SE e SO causam a inversão do fluxo aumentando o nível de água. Embora esteja localizada em uma área de micromaré (0,47m), as marés meteorológicas induzidas por ventos de sul podem elevar o nível acima de 2 m. Este fluxo bidirecional propicia o desenvolvimento de um delta de maré vazante e um esporão arenoso adjacente a foz. Fotografias áreas combinadas com cartas batimétricas permitiram traçar a evolução morfológica do esporão arenoso. Durante este período o esporão cresceu 427m na direção noroeste ao mesmo tempo em que seu comprimento na direção norte sul cresceu 304,5m. A origem, evolução e estabilização destas feições ao longo da margem leste tem sido freqüente mesmo após a construção de dois molhes convergentes. O propósito deste trabalho é discutir o modelo de evolução deste esporão arenoso sujeito a fluxo bi-direcional em uma costa sujeita a influência de marés meteorológicas.
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Geomorphologic evolution of a sand spit located in the mouth of a choked coastal lagoon. Lagoa dos Patos: Southern Brazil
(2004) Antiqueira, Jose Antonio Fonseca de; Calliari, Lauro Júlio; Fontoura, Jose Antonio Scotti
The estuarine portion of the Patos Lagoon behaves as a choked lagoon where circulation patterns are driven mostly by wind and freshwater runoff which can reach up to 10,000 m3/s during the rainfall season. Wind direction influences both local and large-scale circulation patterns. Under NE winds pressure gradient raises along the inlet and retreating coastal waters favors flushing of the lagoon water. Contrarily, a SE and SW wind causes inversion of flow raising the water level in the northern part of both the inlet and the main lagoon body. Although being located in a microtidal area with a mean annual daily range of 0.47m, storm surges induced by southern winds can raise the level up to 2 m. As a result of the strong bi-directional flow an ebb tide delta and sand spit developed in the inner portion of the inlet. A historical sequence of aerial photogrammetry combined with bathymetric charts, (82 years) allowed tracking the morphological evolution of the sand spit located at the extreme end of the inlet. During this period, the spit grew 427 m in the northwest direction at the same time that its north to south length was reduced 304.5 m. The origin, evolution and stabilization of these features along the east margin had been quite frequent even after the construction of two convergent jetties which stabilized the inlet mouth.
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Morphology and dynamics of the base of the western jetty, probable area for the Rio Grande port pilot station, RS State, Brazil
(2009) Hartmann, Carlos; Arejano, Tadeu Braga; Antiqueira, Jose Antonio Fonseca de
The Rio Grande port has suffered accelerated growth over the past few years, a faet which has provoked the arrival of new enterprises, determining a restructuring (change) in the zoning plan of the organized port. The pilot station of the Barra is presently located at the intermediat portion of the Rio Grande Super port. Western margin of the access canal, and in order to improve assistance and navigation safety, it will be transferred to an area closer to the lagoon mouth; such area will be determined by the new zonig plan. At this area, provided by the port, a marina with the entire basic infrastucture for the exercise of piloting will be constructed. This work deals with the acquisition of information consernig the base of the Western Jetty, area located at the Western margin or the port's canal, solicited by the enterprise for the installation of the new piloting station. Seasonal surveys of local environmental conditions and plane-atimetry, utilizing DGPS, were performed, as well as: classification of the botton type utilizing the sieving method,based on the Wentworth scale; mapping of biota and analisys of dynamics with observation of waves and wind data; obtainment f 35 mm digital aerial photographs with the ADAR 1000 system at visible and infrared modes, total station Nikon ® – DTM 330, and in situ photographs. Results demonstrated that the installation of the terminal will bring improvements to the area, with no enveronmental inconvenience and in case implanted, will be extremely useful for portuary activit and port administration.
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Perigos e riscos associados a processos costeiros no litoral do RS: uma síntese
(2010) Calliari, Lauro Júlio; Guedes, Rafael Marcondes Carvalho; Pereira, Pedro de Souza; Lélis, Renato José Furigo; Antiqueira, Jose Antonio Fonseca de
Some processes related to hydrodynamics, geomorphology and sediment movement represent coastal hazards and risks along the littoral of Rio Grande do Sul (RS) state in southern Brazil. The hazards imply in coastal erosion, habitat loss and environmental change. The risks are related to serious accidents including fatalities to the coastal users. Shoreface morphology, storms and washouts induce erosion at specific locations of the coastline. Storms and washouts, together with beach morphodynamics and depositional processes both aeolian and hydrodynamic embody latent risks to the physical integrity of people that live in and use this environment. Wave refraction patterns from SE to SW cause erosion in two coastal sectors at the proximities of Conceição Lighthouse and Hermenegildo Beach respectively located at the central and southernmost portion of the RS coastline. In both areas, the high number of washouts amplifies the erosion destroying foredunes and the subaerial beach. In addition, the lowlands of the barrier adjacent to small pocket lagoons in the northern littoral are more susceptible to washout erosion. Both, the refraction patterns and the washouts can be associated with two storms tracks and extra-tropical cyclones which magnify erosion and inundation of the coastal zone. The combination of higher population during summer seasons and intermediate beaches with considerable amounts of medium sand make beaches from the northern littoral and extreme south more risky for bathers. Coastline orientation in relation to the predominant NE wind causes wind-blow sand to invade the coastal plain in the form of transgressive dunes causing several hazards mainly in the northern littoral between Tramandaí and Mostardas. Short-term effects associated with episodic events of mud deposition during heavy storms on Cassino Beach influence the morphodynamics behavior on the sectors affected by the mud deposits creating coastal risks relating to beach usage.
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Variação decadal dos perfis praiais do Farol da Conceição e Terminal
(2007) Pereira, Pedro de Souza; Calliari, Lauro Júlio; Barletta, Rodrigo do Carmo; Antiqueira, Jose Antonio Fonseca de; Guedes, Rafael Marcondes Carvalho
As praias da costa do estado do Rio Grande do Sul têm sido estudas desde o início da década de noventa. Dos aproximados 620 quilômetros de costa, duas praias merecem destaque: Farol da Conceição e Terminal Turístico. O objetivo do presente estudo é descrever variações apresentadas pelos perfis amostrados nessas localidades. Para calculo das taxas de retração e progradação da linha de costa foram utilizados os métodos de pontos finais e regressão linear. Através dos perfis estudados foi possível constatar um grande desenvolvimento ocorrido no campo de dunas frontais cuja causa acredita-se estar relacionada a ações de manejo. Taxas de retração de 1,5 e 3,7 m/ano foram encontradas para o Farol da Conceição bem como taxas de progradação de 3,2 a 4,7m/ano para o Terminal Turístico. Não houve uma grande diferença entre as taxas encontradas com os diferentes métodos utilizados.
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Vulnerability to sea level rise of an estuarine island in southern Brazil
(2010) Tagliani, Carlos Roney Armanini; Calliari, Lauro Júlio; Tagliani, Paulo Roberto Armanini; Antiqueira, Jose Antonio Fonseca de
This article presents a sea level rise vulnerability map built for Marinheiros Island, South Brazil, through specific routines for support decision in a Geographical Information System. A previous environmental diagnosis allowed the recognition of 5 vulnerability factors including physical, biotic and socio-economic variables. Each one was standardized to a continuous scale of values using the fuzzy approach, and later, analyzed together by multi-criterion evaluation module of the software to produce the final map. The most vulnerable areas are located at the northeast margins of the island as a result of the coincidence of several of the considered factors. In the remaining areas the vulnerability values decrease progressively from the margins to the center. Although the final result tends to be subjective because it is the decision maker what determines the criteria, the factors, the individual weighting and the decision rules, exercises of projection as performed in this work are very useful to explore certain alternatives and to insert sea level variable in the urban planning.