Artigos de Revista

The characterisation of the dynamics of Figueira da Foz beach, in the West coast of Portugal, is presented based on the analysis of previous studies and results obtained from the application of a numerical model. Advances on the understanding of the beach dynamics have been achieved by the quantification of the annual and seasonal longshore transport and several beach profile parameters. An evaluation of the contribution of the wave climate components on the longshore transport was also obtained. The results allow sustaining a prediction of the effect of a future change of the wave climate on the longshore transport. Figueira da Foz shoreline change was simulated based on different conceptual scenarios and the results, although not quantitatively conclusive, allow the understanding of the influence of the neighbouring beach hard rock outcrops on the recent evolution.

Barotropic tidal propagation, circulation and salinity intrusion in the Guadiana estuary are described, based on two-dimensional numerical simulations supported by field data. Results are integrated through selected indicators, which provide detailed insight into the variability of the estuarine dynamics with the tides, the river flow and the spatial location. The estuarine dynamics is strongly affected by the generation of non-linear tidal constituents. Quarter-diurnal constituents distort the tide along the estuary, resulting in strong flood dominance. As a consequence, the estuary experiences accretion for low river flows. Residual velocities are directed upstream in shallow areas and downstream in the main channel. This pattern is responsible for higher salinities near the eastern margin, explaining the observed cross-sectional distribution of benthic organisms. The Coriolis effect and the residual currents patterns contribute to the efficient mixing of the river plume, promoting the renewal of the estuarine water. Residence times, computed with a new method based on particle tracking simulations, vary between four months and one week, for river flows between 8 and 300 m3/s. Maximum salinity intrusion depends on the tidal amplitude, which accounts for 8 km of its variability, and on the river flow. For very low river flows, the 0.5 isohaline penetrates up to 40 km into the estuary. The oligohaline, mesohaline and polyhaline regions extend for about 5 km each, and their locations shift by about 20 km with the tide. The estuary is stratified for river flows above 100 m3/s, and well mixed for river flows below 10 m3/s.

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Natural or induced floods are of increasing concern to water managers and civil protection services for three main reasons. Firstly, a continuous and unconscious increase of social pressure in the flooding valleys amplifies flood vulnerabilities and consequently natural or induced flood risk. Secondly, the alarming forecasts of the impact of potential climate changes on water resources, in spite of the high uncertainty associated to these forecasts, points out to larger flood hazards. Thirdly, dam-break induced accidents may occur more frequently due to infrastructure aging. Emergency Planning is a non-structural measure to minimise flood impacts playing an important role in crisis management. In fact, if a disaster cannot be avoided, individual and social structure preparedness may be of great help in risk reduction. An Internet-based system that supports flood emergency management is presented in this paper. This application is part of a more complete system developed with the goal of endowing the Portuguese water authorities, dam owners and the civil protection system with adequate tools to store and easily retrieve information on dams and their downstream valleys, to model the flood wave induced by a dam break and, eventually, to manage the response to flood-induced catastrophes.

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A relação entre o habitat e os processos de (des)integração social de minorias étnicas provenientes dos PALOP e da população cigana a residirem nas áreas metropolitanas de Lisboa e do Porto constitui o cerne do presente artigo. Faz-se uma breve apresentação dos eixos problemáticos que orientaram a pesquisa empírica a partir da qual se discute a relação acima referida. O artigo dá, ainda, conta de traços e tendências - sócio-demográficas, de trajectórias de emigração, de atitudes face à escola, de desempenhos económico-profissionais e de estratégias face às redes de suporte social - que ajudam a conferir identidade às minorias em presença. A fechar destacam-se algumas das marcas reveladas pela referida pesquisa e procura-se dar um contributo que ajude a equacionar o desafio com que se confronta a sociedade portuguesa, face à crescente diversidade cultural que se consolida no seu seio.

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Experimental determination of wastewater characteristics and model parameters is required for robust modeling of in-sewer processes. Respirometric assays can be used to determine some of the model parameters thus reducing the number of model parameters to be determined by model calibration and verification. However, the model structure has to be considered for this purpose. The model used consists of three main modules, namely hydrodynamics, advection and dispersion, and biochemical processes, and is applicable in sewers under aerobic dry weather flow conditions. A procedure is proposed to determine important chemical oxygen demand (COD) fractions and model parameters for biochemical processes. Cumulative oxygen utilization proves to be useful for process identification providing extra information on substrate availability during the assay. While the values obtained for both COD fractions and parameters depend on the model structure adopted, the procedure used can easily be adapted to other model formulations.

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A modernização da rede ferroviária portuguesa inclui, entre outros aspectos, trabalhos demelhoramento e de renovação em diversas linhas. No que se refere à plataforma ferroviária, pretende-seque esta responda adequadamente aos novos requisitos, os quais estão relacionados com o aumento davelocidade dos comboios de passageiros, com o aumento da carga máxima por eixo dos comboios demercadorias e ainda com o aumento do volume de tráfego. Neste trabalho abordam-se alguns dosaspectos relacionados com as características da plataforma, as quais são determinantes para ocomportamento global da via. Apresentam-se alguns aspectos da metodologia utilizada nos estudosrealizados, a partir de 1998, para a renovação da plataforma ferroviária da Linha do Norte, no âmbito doProjecto de Modernização.