Search results for "Spatial"
showing 10 items of 2121 documents
Intensity and spatial extent of droughts in southern Africa
2005
International audience; The standardized precipitation index allows for monitoring the intensity and spatial extent of droughts at different time scales. We used it to do a retrospective analysis of the spatial extent of droughts in Southern Africa (South of 10°S), from 1901 to 1999. Accordingly, the 8 most severe droughts at the 6-month scale (October–April) for the summer rainfall region of Southern Africa ended in 1916, 1924, 1933, 1949, 1970, 1983, 1992 and 1995. At the 2-year scale, they ended in 1906, 1933, 1983, 1984, 1992, 1993, 1995 and 1996. Areas affected by those droughts ranged from 3.4 to 2 106 km2. Eight of those 12 years are El Niño years. Preliminary data indicates that 200…
A Semantic Web Approach for Geodata Discovery
2013
International audience; Currently, vast amounts of geospatial information are o ffered through OGC's services. However this information has limited formal semantics. The most common method to search for a dataset consists in matching keywords to metadata elements. By adding semantics to available descriptions we could use modern inference and reasoning mechanisms currently available in the SemanticWeb. In this paper we present a novel architecture currently in development in which we use state of the art triplestores as the backend of a CSW service. In our approach, each metadata record is considered an instance of a given class in a domain ontology. Our architecture also adds a spatial dat…
Use of Geospatial Analyses for Semantic Reasoning
2010
International audience; This work focuses on the integration of the spatial analyses for semantic reasoning in order to compute new axioms of an existing OWL ontology. To make it concrete, we have defined Spatial Built-ins, an extension of existing Built-ins of the SWRL rule language. It permits to run deductive rules with the help of a translation rule engine. Thus, the Spatial SWRL rules are translated to standard SWRL rules. Once the spatial functions of the Spatial SWRL rules are computed with the help of a spatial database system, the resulting translated rules are computed with a reasoning engine such as Racer, Jess or Pellet.
LKS-92 Coordinates Transformation to ITRF2000
2014
LKS-92 is Latvian geodetic coordinate system used as an EUREF89 realization in Latvia. LKS-92 is official coordinate system for procuring of essential geospatial data. For aeronautical and other purposes ITRF2000 is used in publication of geospatial data. Research is done to obtain transformation parameters from LKS-92 realization epoch 1992.75 through LatPos to ITRF2000 epoch 2000.00. Valuation of two different coordinate adjustment strategies and accuracy of parameters is done. Results of research could be used for transformation from LKS-92 to ITRF2000 for all kind of geospatial data.
Geomorphologic Risk Modelling of the Sibiu Depression Using Geospatial Surface Analyses
2011
Extreme events in general, and the geomorphologic ones in particular, are highly topical problems. There were addresses by many researchers in the field of geology and physical geography (more specific by the climatologists and geomorphologists), but also by biologists, chemists, ecologists, etc. These are studied through the analysis of some types of processes and production mechanisms, and secondly by the effects they create on other environmental subsystems.
ASSESSMENT OF ECOSYSTEM SERVICES FOR PLANNING OF GREEN INFRASTRUCTURE AT THE REGIONAL LEVEL
2019
Ecosystem services (ES) are defined as the benefits that human beings derive from ecosystem functions. Assessment and mapping of these benefits are crucial for sustainable environmental planning and future natural capital. Green infrastructure (GI) is natural or semi-natural territories that provide wide range of ES. Human affected ecosystems tend to fail to provide certain sets of ES due to the trade-offs among those services, which could be mitigated through implementation of GI. Mapping of ES, as well as assessing the interactions among various ES and analysing their supply potential’s cold/hot spots considerably enhances and substantiates the planning process of GI, particularly at the …
Spatial analysis of the relationship between mortality from cardiovascular and cerebrovascular disease and drinking water hardness
2004
Journal Article; Research Support, Non-U.S. Gov't; Reproduced with permission from Environmental Health Perspectives. Previously published scientific papers have reported a negative correlation between drinking water hardness and cardiovascular mortality. Some ecologic and case-control studies suggest the protective effect of calcium and magnesium concentration in drinking water. In this article we present an analysis of this protective relationship in 538 municipalities of Comunidad Valenciana (Spain) from 1991-1998. We used the Spanish version of the Rapid Inquiry Facility (RIF) developed under the European Environment and Health Information System (EUROHEIS) research project. The strateg…
Econométrie spatiale (2, Hétérogénéité spatiale)
2000
Spatial econometric methods aim at taking into account the two special characteristics of spatial data: spatial autocorrelation, which is the lack of independence between geographical observations, and spatial heterogeneity, which is related to the differentiation of variables and behaviors in space. These techniques have been mostly developed the last ten years and are more often applied in empirical studies with geographical data. The aim of this article is to present the way spatial autocorrelation and spatial heterogeneity can be incorporated in regression relationships and to present the estimation and inference procedures adapted to the models incorporating these two effects. This art…
Convergence of European regions (an approach by spatial econometrics)
2000
The aim of this paper is the analysis of spatial dependence in convergence processes applied to European regions. First, we apply the recently developed exploratory spatial data analysis (Anselin, 1996) in order to describe more precisely the geographical dynamics of European regional income growth patterns. New insights are brought to the usual cr-convergence measure, which hides geographical patterns that may fluctuate over time. Second, we test the presence of spatial autocorrelation in /^-convergence models by using spatial econometrics methods (Anselin, 1988 ; Anselin and Florax, 1995). We compare the results with and without spatial autocorrelation in order to assess the effect of geo…
Estimation of leaf area index using PROSAIL based LUT inversion, MLRA-GPR and empirical models: Case study of tropical deciduous forest plantation, N…
2020
Abstract Forests play a vital role in biological cycles and environmental regulation. To understand the key processes of forest canopies (e.g., photosynthesis, respiration and transpiration), reliable and accurate information on spatial variability of Leaf Area Index (LAI), and its seasonal dynamics is essential. In the present study, we assessed the performance of biophysical parameter (LAI) retrieval methods viz. Look-Up Table (LUT)-inversion, MLRA-GPR (Machine Learning Regression Algorithm- Gaussian Processes Regression) and empirical models, for estimating the LAI of tropical deciduous plantation using ARTMO (Automated Radiative Transfer Models Operator) tool and Sentinel-2 satellite im…