Exploring a Geographical Dataset with GEOLIS

International audienceGeographical data are mainly structured in layers of information. However, this model of organisation is not convenient for navigation inside a dataset, and so limits geographical data exploration to querying. We think information retrieval could be made easier in GIS by the introduction of a navigation based on geographical object properties. For this purpose, we propose a prototype, GEOLIS1, which tightly combines querying and navigation in the search process of geographical data. GEOLIS relies on Logical Information Systems (LIS), which are based on Formal Concept Analysis (FCA) and logics. In this paper, we detail data organisation and navigation process in GEOLIS. We also present the results of an experimentation led on a real dataset

Handling Spatial Relations in Logical Concept Analysis to Explore Geographical Data ⋆

Abstract. Because of the expansion of geo-positioning tools and the democratization of geographical information, the amount of geo-localized data that is available around the world keeps increasing. So, the ability to efficiently retrieve informations in function of their geographical facet is an important issue. In addition to individual properties such as position and shape, spatial relations between objects are an important criteria for selecting and reaching objects of interest: e.g., given a set of touristic points, selecting those having a nearby hotel or reaching the nearby hotels. In this paper, we propose Logical Concept Analysis (LCA) and its handling of relations for representing and reasoning on various kinds of spatial relations: e.g., Euclidean distance, topological relations. Furthermore, we present an original way of navigating in geolocalized data, and compare the benefits of our approach with traditional Geographical Information Systems (GIS).

Monitoring dune vegetation changes and associated driving forces at Culatra Island, Algarve, Portugal

As dunas do sistemas de ilhas barreira suportam uma grande variedade de vegetação que estabilizam e promovem o crescimento das dunas protegendo as zonas costeiras. Os habitats de vegetação diferem entre dunas frontal, interdunar e posterior de acordo com a sucessão evolutiva e a exposição da vegetação a fatores naturais como o vento e ondas. Esses fatores podem ter um efeito significativo sobre a geomorfologia das dunas. Além disso, a geomorfologia das dunas pode influenciar a ecologia, devido a evolução eco geomorfológicos que existem nas dunas costeiras, tais como os fatores reguladores "top down", como a areia eólica, e "bottom up", como as condições para um crescimento ótimo de sucessão comunitária. O sistema de ilhas barreira da Ria Formosa é uma reserva natural protegida desde 1987, esse sistema é constituído por uma lagoa protegida por cinco ilhas barreira e duas penínsulas separadas canais de marés, denominados como barras. Dentro deste sistema de ilhas barreira, a Ilha da Culatra contém uma importante comunidade pesqueira, presença de trilhas e colônias locais da gaivota-de-patas-amarelas (Larus Michahellis). Visto que a Ilha da Culatra contém “dunas cinzentas” que estão listadas como um tipo de habitat prioritário, de acordo com a diretiva europeia, foi necessário realizar um estudo rentável sobre o estado da vegetação. Foram investigados fatores que possam contribuir para a perturbação do sistema de vegetação das dunas da ilha da Culatra. O estudo na presente dissertação, desenvolveu um índice para calcular a perturbação da vegetação dunar dentro da Ilha da Culatra utilizando técnicas de detecção remota com a utilização de Sistemas de Informação Geográfica (SIG). Os materiais utilizados para a análise foram ortofotografias e imagens do Google Earth. Estes materiais e ferramentas permitiram classificar a vegetação para completar um índice de perturbação da vegetação. O índice foi realizado através da composição colorida de ortofotografias a cores verdadeiras. Para complementar os dados, foi também utilizada a imagem do Google Earth. As fontes de perturbação foram identificadas pela sobreposição de elementos antropogénicos digitalizados. Este estudo identificou a mudança no estado da vegetação de 2005 para 2017, envolvendo o aumento da perturbação. Constatou-se que a principal causa desta perturbação estava relacionada com marcas causadas por veículos na ilha. O índice e os métodos destacaram a necessidade da utilizar imagens de melhor qualidade, que podem ser de grande utilidade para estudos futuros devido à simplicidade dos métodos e à sua abordagem rentável. Além disso, este método e índice pode ser altamente transferível para outros sistemas dunares e pode ser utilizado como base de referência para o estudo posterior da vegetação dunar na ilha da Culatra, chamando a atenção e importância para a conservação do sistema dunar.Barrier island sand dune systems support a high variety of plant communities, which stabilise and promote growth of dunes protecting inland areas. According to plant succession and exposure, to natural factors such as wind and ocean, vegetation habitats differ between foredune, interdune and backdunes. This can have a significant effect on the geomorphology of the dunes. Moreover, the geomorphology of dunes can influence the ecology, due to the eco-geomorphological feedbacks that exist in coastal dunes such as “top down” (for example aeolian sand) and “bottom up” (such as the conditions for optimal growth of community succession) regulating factors. A protected natural reserve since 1987, the Ria Formosa consists of a lagoon protected by five barrier islands and two peninsulas supported by tidal inlets. Within this barrier system, Culatra Island contains a significant fishing communities, the presence of local footpaths and colonies of the Yellow legged gull (Larus Michahellis). Since Culatra Island contains “grey dunes" which are listed as a priority habitat type according to the EU habitats directive, it was therefore necessary to conduct a cost-effective study on the state of the vegetation and whether any factors are contributing to the perturbation of the Culatra Island dune vegetation system. This study developed an index to calculate dune vegetation perturbation within Culatra island using remote sensing techniques within a Geographical Information Systems environment (GIS). The materials used for the analysis were orthophotos and Google Earth imagery. These materials and tools enabled the ability to classify vegetation to complete a vegetation perturbance index. The index was carried out by the classification of orthomosaicked true colour images. To complement the data, Google Earth imagery was also used. Sources of perturbation were identified by the superimposition of digitized anthropogenic elements. This study identified the change in vegetation state from 2005 to 2017 involving the increase of perturbation. It was found that the main cause of this perturbation was related to track marks caused by vehicles on the island. The index and methods highlighted the need to use better quality imagery but can be of great use for further studies due to the simplicity of the methods and its cost-effective approach. Furthermore, this method and index can be highly transferable to other dune systems and can be utilized as a baseline for further study of dune vegetation on Culatra island, drawing attention and importance to the conservation of the system

Urban transport, pedestrian mobility and social justice: a GIS analysis of the case of the Lisbon Metropolitan Area

Urban transport projects redistribute accessibility and environmental quality across the city, potentially creating disadvantages for some social groups. This thesis investigates whether these effects are cumulative or compensatory in the case of the Lisbon Metropolitan Area, analysing inequalities in the light of competing principles of social justice. The novelty of this research lies in the interpretation of local environmental effects as factors restraining the mobility of pedestrians. We propose a series of GIS-based indicators, including community severance and noise exposure of pedestrians on the way to work and walking around their neighbourhoods. We found that projects giving priority to private transport have a disproportionate effect on the pedestrian environment of the elderly and low-qualified populations. The analysis addresses two of the most pressing issues in transport equity analysis. The first is the spatial heterogeneity in patterns of inequality. We estimate relationships between socio-economic variables and indicators of the local effects of transport using alternative comparison areas, defined in terms of centrality and commuting destinations. We found that the social distribution of those effects is sensitive to location and spatial scale. The second issue is the nature of the processes leading to inequalities. We show that accessibility and pedestrian mobility have an influence on neighbourhood socio-economic recomposition and on patterns of settlement in newly developed areas. We also analyse the implications of integrating distributive concerns in transport planning. In the design of the optimal route alignment for a new road, these concerns may increase aggregate community severance costs. In the application of traffic restriction policies, there are trade-offs between the welfare of different groups of concern in terms of time to work and pedestrian exposure to noise. In both cases, the achievement of equity may not be compatible with the party-political interests of the policy-maker

Geological recognition of abrupt marine invasions in two coastal areas of Portugal

This thesis was submitted for the award of Master of Philosophy and awarded by Brunel UniversityAbrupt marine invasions such as tsunamis and storms are particularly devastating for coastal areas. They may also leave a permanent record in the sedimentary deposits which is the principal focus of this thesis. In historical times the most destructive tsunami that affected Europe was the AD 1755 Lisbon. The effects and consequences of the AD 1755 tsunami are presented. The causes, propagation and behaviour of tsunamis are also discussed. Sedimentological criteria to identify abrupt marine invasions in the stratigraphic column are presented from literature. This thesis aims to contribute to a better understanding of the signature left by abrupt marine invasions in coastal stratigraphy by investigating the nature of the sedimentary record associated with tsunamis in a region of their known impact. A wide range of proxies was used to detected tsunami and storm deposits in 2 coastal areas of Portugal. The techniques used include stratigraphic description, grain size analysis, digital and x-ray photography, magnetic susceptibility, macrofossils analysis, geochemical analysis and 210Pb and Optically Stimulated Luminescence dating. The investigated areas (e.g. Lagoa de Óbidos (Central Portugal) and Martinhal (South Portugal)) were affected by the AD 1755 tsunami. The locations have similar geomorphological features and are both susceptible to major abrupt marine invasions. Results show that an abrupt event deposited unique sedimentary units in both locations. A similar age for the event was established. A considerable number of tsunami sedimentary characteristics were detected in both units. However, a key outcome of this research is the demonstration of the difficulty of distinguishing between sedimentary deposits laid down by tsunamis, and those deposits resulting from storm action; consequently the geological record of tsunamis almost certainly underestimates their frequency

Água e Território: um tributo a Catarina Ramos

info:eu-repo/semantics/publishedVersio

Exploring a Geographical Dataset with GEOLIS

International audienceGeographical data are mainly structured in layers of information. However, this model of organisation is not convenient for navigation inside a dataset, and so limits geographical data exploration to querying. We think information retrieval could be made easier in GIS by the introduction of a navigation based on geographical object properties. For this purpose, we propose a prototype, GEOLIS1, which tightly combines querying and navigation in the search process of geographical data. GEOLIS relies on Logical Information Systems (LIS), which are based on Formal Concept Analysis (FCA) and logics. In this paper, we detail data organisation and navigation process in GEOLIS. We also present the results of an experimentation led on a real dataset