30,613 research outputs found
Exploratory analysis of OpenStreetMap for land use classification
In the last years, volunteers have been contributing massively to
what we know nowadays as Volunteered Geographic Information.
This huge amount of data might be hiding a vast geographical
richness and therefore research needs to be conducted to explore
their potential and use it in the solution of real world problems. In
this study we conduct an exploratory analysis of data from the
OpenStreetMap initiative. Using the Corine Land Cover database
as reference and continental Portugal as the study area, we
establish a possible correspondence between both classification
nomenclatures, evaluate the quality of OpenStreetMap polygon
features classification against Corine Land Cover classes from
level 1 nomenclature, and analyze the spatial distribution of
OpenStreetMap classes over continental Portugal. A global
classification accuracy around 76% and interesting coverage
areas’ values are remarkable and promising results that
encourages us for future research on this topic
Using Geographic Information Science to Map the Flight of the Regicides in Seventeenth- century New England
In mid-seventeenth century two of the judges who condemned King Charles I of England to death became regicide fugitives when his son came to the throne as Charles II. The two men fled to New England and eluded their Royalist pursuers for twenty years. I am attempting to track their travels and hideouts through standard historical research and, more recently, the use of Geographic Information Science (GIS), a form of digital mapping technology which organizes information in a geographical format by adding spatial coordinates to existing data to form a geodatabase. This article describes the application of GIS to test an eighteenth-century historian’s description of the regicides’ movements in Connecticut during the spring and summer of 1661
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Ecological thresholds and large carnivores conservation: Implications for the Amur tiger and leopard in China
The ecological threshold concept describes how changes in one or more factors at thresholds can result in a large shift in the state of an ecosystem. This concept focuses attention on limiting factors that affect the tolerance of systems or organisms and changes in them. Accumulating empirical evidence for the existence of ecological thresholds has created favorable conditions for practical application to wildlife conservation. Applying the concept has the potential to enhance conservation of two large carnivores, Amur tiger and leopard, and the knowledge gained could guide the construction of a proposed national park. In this review, ecological thresholds that result from considering a paradigm of bottom-up control were evaluated for their potential to contribute to the conservation of Amur tiger and leopard. Our review highlights that large carnivores, as top predators, are potentially affected by ecological thresholds arising from changes in climate (or weather), habitat, vegetation, prey, competitors, and anthropogenic disturbances. What's more, interactions between factors and context dependence need to be considered in threshold research and conservation practice, because they may amplify the response of ecosystems or organisms to changes in specific drivers. Application of the threshold concept leads to a more thorough evaluation of conservation needs, and could be used to guide future Amur tiger and leopard research and conservation in China. Such application may inform the conservation of other large carnivores worldwide
Toward user oriented semantic geographical information systems
User Oriented Geographical Information Systems, a recent adaptation of classical GIS concepts to everyday usage, are becoming more and more present in the web landscape. Recent developments show the need of adding higher semantic levels to the existing frameworks, to improve their usage, as well as to ease scalability. We point out limits of actual examples, related to handling heterogeneous data, scalability issues, and expressiveness, and suggest a framework for building a Semantic User Oriented GIS. Notably this framework aims to address the peculiarities of the geographical space domain, and to offer a cognitively sound interface to the user
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Exploring Uncertainty in Geodemographics with Interactive Graphics
Geodemographic classifiers characterise populations by categorising geographical areas according to the demographic
and lifestyle characteristics of those who live within them. The dimension-reducing quality of such classifiers provides a simple and effective means of characterising population through a manageable set of categories, but inevitably hides heterogeneity, which varies within and between the demographic categories and geographical areas, sometimes systematically. This may have implications for their use, which is widespread in government and commerce for planning, marketing and related activities. We use novel interactive graphics to delve into OAC – a free and open geodemographic classifier that classifies the UK population in over 200,000 small geographical areas into 7 super-groups, 21 groups and 52 sub-groups. Our graphics provide access to the original 41 demographic variables used in the classification and the uncertainty associated with the classification of each geographical area on-demand. It also supports comparison geographically and by category. This serves the dual purpose of helping understand the classifier itself leading to its more informed use and providing a more comprehensive view of population in a comprehensible manner. We assess the impact of these interactive graphics on experienced OAC users who explored the details of the classification, its uncertainty and the nature of between – and within – class variation and then reflect on their experiences. Visualization of the complexities and subtleties of the classification proved to be a thought-provoking exercise both confirming and challenging users’ understanding of population, the OAC classifier and the way it is used in their organisations. Users identified three contexts for which the techniques were deemed useful in the context of local government, confirming the validity of the proposed methods
Assessing the suitable habitat for reintroduction of brown trout (Salmo trutta forma fario) in a lowland river : a modeling approach
Huge efforts have been made during the past decades to improve the water quality and to restore the physical habitat of rivers and streams in western Europe. This has led to an improvement in biological water quality and an increase in fish stocks in many countries. However, several rheophilic fish species such as brown trout are still categorized as vulnerable in lowland streams in Flanders (Belgium). In order to support cost-efficient restoration programs, habitat suitability modeling can be used. In this study, we developed an ensemble of habitat suitability models using metaheuristic algorithms to explore the importance of a large number of environmental variables, including chemical, physical, and hydromorphological characteristics to determine the suitable habitat for reintroduction of brown trout in the Zwalm River basin (Flanders, Belgium), which is included in the Habitats Directive. Mean stream velocity, water temperature, hiding opportunities, and presence of pools or riffles were identified as the most important variables determining the habitat suitability. Brown trout mainly preferred streams with a relatively high mean reach stream velocity (0.2-1m/s), a low water temperature (7-15 degrees C), and the presence of pools. The ensemble of models indicated that most of the tributaries and headwaters were suitable for the species. Synthesis and applications. Our results indicate that this modeling approach can be used to support river management, not only for brown trout but also for other species in similar geographical regions. Specifically for the Zwalm River basin, future restoration of the physical habitat, removal of the remaining migration barriers and the development of suitable spawning grounds could promote the successful restoration of brown trout
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