Papers

SOPRO1.0, constituiu a primeira versão do pacote de informática desenvolvido no Laboratório Nacional de Engenharia Civil, para a caracterização da agitação marítima em zonas costeiras e de simulação da navegação no acesso ou no interior de zonas portuárias. É composto por um conjunto de bases de dados, uma interface com o utilizador e um conjunto de módulos de cálculo. A interface com o utilizador permite o armazenamento e manipulação de dados, a execução dos modelos de propagação da agitação marítima e de simulação da trajectória de navios, assim como a obtenção dos resultados e a criação das correspondentes visualizações gráficas. O pacote foi criado no sistema gestor de base de dados Microsoft Access™, utiliza o Visual Basic for Applications (VBA) como linguagem de programação e todos os modelos/módulos são executados num computador pessoal. Neste artigo, apresentam-se os desenvolvimentos mais recentes de alguns dos módulos do pacote SOPRO1.0, isto é, a versão SOPRO3.0. As alterações introduzidas incluem a reestruturação das interfaces, melhoramentos na eficiência dos algoritmos, um módulo de geração de malhas de elementos finitos e novas rotinas para execução remota dos modelos numéricos de propagação de ondas em estações de trabalho que correm um sistema operacional UNIX-like, e que tipicamente têm maior capacidade de memória e CPU do que um computador pessoal.O pacote é aplicado a um caso de estudo da costa portuguesa e a outro na costa do Brasil, nos quais as novas potencialidades do SOPRO3.0 são ilustradas.

In this work, we present the results of an analytical method developed for detailed pigment identification, stratigraphy, and degradation of the paint layers of mural paintings applied in the study of the 17th century frescoes from the Misericordia Church of Odemira (Southwest Portugal). In situ X-ray fluorescence spectrometry analyses were performed on three panels of the mural paintings and complemented by colorimetric measurements. The different color areas were also sampled as microfragments (approx. 1 mm2)that were studied as taken or mounted in epoxy resin to expose the different paint layers. The microfragments of paint layers and their cross sections were characterized by optical microscopy and scanning electron microscopy coupled with energy dispersive X-ray spectrometry. Furthermore, elemental analysis was obtained with spatially resolved confocal synchrotron radiation micro-X-ray fluorescence spectrometry performed at ANKA synchrotron FLUO beamline. Occasionally, phase analysis by micro-X-ray diffraction was also performed. Results from the different techniques allowed pigment identification and, in some cases, the evaluation of color changes due to degradation processes and, considering the Southern Portugal geology, the identification of their possible provenance. The pigments used were essentially yellow, brown and red ochres, smalt blue, copper green, and black earths, probably from local sources.

The hydrodynamics of the surf zone in front of collapsing coastal dunes are examined. The data was gathered during the HYDRALAB-III funded Transnational Access experiment performed at the CIEM large-scale wave flume. Here, it is presented results of the cross-shore evolution of several flow parameters at four positions. Despiked and band-pass filtered ADV velocity data were used to enable a focus on only the short-wave component. As the waves approach the shore they reduce their (velocity) skewness, but increase their vertical asymmetry. Despite the non-negligible wave reflection, the theoretical wave model of Abreu et al. (2010) was applied to successfully reproduce the measured velocities. Lastly, an estimate of the bed shear stress exerted by the shortwave components is presented.

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ABSTRACT: Local engineering precision networks are currently used to monitor the displacements of large dams, with safety control purposes. These one, two or three-dimensional networks are local, be-cause they are tied to local reference frames, and they are precision networks, because they aim at millimetric, or even submillimetric, accuracy. The most important obstacles to such an accuracy are the instrumental and environmental systematic errors. The atmospheric refraction, which cau-ses curvature of the path of the electromagnetic waves and changes its propagation velocity, is the major source of systematic errors. Effective measurement quality control strategies are of utmost importance to guarantee the quality of the results (displacements). The paper presents a quality control strategy supported by random quadratic forms that result from the decomposition of the Mahalanobis squared norm of the residuals vector. The strategy is compared to the well known da-ta-snooping method with regard to the quality control and parameter estimation performances.

Due to the increasing demand of sand for construction and beach nourishment, offshore extraction is being considered as an alternative source. Long term morphological changes caused by such an extraction must be predicted because they can affect the sediments budget and potentially promote coastal erosion. Numerical models are powerful tools that can help in the evaluation of environmental impacts induced by this activity. The objective of this study is to describe the morphodynamics in the area surrounding a sandpit through the use of the MORSYS2D modelling system. The sandpit under study is located offshore Vale do Lobo, an important beach and golf resort located on the Southern Portuguese coast. The numerical solutions of the mean flow and the wave height around the pit were obtained with MORSYS2D between March 28 and April 29, 2008 when two storm events with significant wave height (Hs) greater than 2.5 m occurred. The numerical results are analysed in terms of the sand fluxes and bathymetry changes induced by wind and tidal currents and wave orbital velocities. The results show the strong impact of storm events in the morphologic evolution of the pit and surrounding area. The value for Hs > 2.5m was also confirmed as determinant for the sediment dynamics.

O artigo desenvolve uma análise sobre as homogeneidades sócio-económicoas e ambientais das zonas costeiras continentais portuguesas, explorando a exposição humana ao risco de erosão costeira e perspectivas interdisciplinares de abordagem sobre os riscos ambientais. A análise desenvolvida cruza indicadores sociais e geofísicos, embora o enfoque de partida privilegie as dimensões sócio-ecológicas dos usos e ocupações humanas do território. O artigo resume actividades concluídas no âmbito de um projecto em curso financiado pela Fundação para a Ciência e Tecnologia, tendo como objectivo principal contribuir para uma gestão integrada das zonas costeiras, desenvolver indicadores de vulnerabilidade e discutir, a propósito do risco de erosão costeira, medidas de prevenção, protecção e socorro.

Porosity and degree of saturation - or the water content - are important parameters for hydrogeological, geotechnical and environmental studies. Geophysical methods, especially the resistivity method, are routinely employed to study the spatial variations of these parameters. Resistivity is highly influenced by the presence of water in pore spaces and hence is well suited for studying the presence of fluids on a site and its saturation condition However, the non-uniqueness of the solution of resistivity models has lead to the joint use of more than one geophysical method in order to reach more accurate geophysical models. In this research work, we have decided to combine resistivity and seismic refraction profiles. The integration of these methods was particularly aimed to obtain 2D sections for estimating porosity, water saturation and volumetric water content rather than to obtain a better geophysical solution. Independently inverted resistivity and P-wave refraction sections are the input data of an iterative process using Simulated Annealing. Empirical equations from literature are used, which relate both the seismic velocity and the electrical resistivity with porosity and water saturation. Several parameters, such as resistivity of water and clay; velocity of water, clay, air and matrix; clay percentage and Archie’s parameters remain constant throughout the process. The values considered for each parameter derive from both the literature and the laboratory measurements. Resistivity and seismic refraction profiles were performed on a site located within LNEC campus. At this site, field measurements of void ratio and volumetric water content were performed at different depths. Soil samples were also collected at three different depths to perform laboratory measurements of these parameters and to determine soil composition. The results were compared with 2D sections of each parameter. The proposed approach was also applied to two other locations with different and well characterised geologies. These tests also allowed us to put into evidence the dependency of the clay content on resistivity. This research has potential fields of application in environmental studies, in particular, as regards the determination of probable pathways of pollutants; in hydrological investigations, in which it can play a role in the study about transport of nutrients; and in geotechnical studies, as it will be able to give a continuous image of the saturation degree of an embankment, for example.

Within the GeoSIS_Lx project, a geotechnical data base is being implemented and methodologies to generate tridimensional geological and geotechnical models of the city of Lisbon are being developed. The generation of the tridimensional model is being pursued through an iterative process using a Geographical Information System (GIS) platform, designed to be open to the use of several technicians that may not be geology or software experts. Geological surfaces were derived based on information interpolated from cross-sections, resulting in a simple model where first order geological patterns are present, following a validation with the cartographic patterns of geological outcrops and with selected information of the geological database. Future developments include refinement of modeling of faults and an automatic validation procedure against the borehole database and geologic cartographic patterns taking into account the data uncertainties. Results indicate that the methodology in this test suits the requisites of the geological formations of Lisbon.

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