Search

Land cover maps contribute to a large diversity of geospatial applications, including but not limited to land management, hydrology, land use planning, climate modeling and biodiversity monitoring. In densely populated and highly fragmented landscapes as observed in the Walloon region (Belgium), very high spatial resolution is required to depict all the infrastructures, buildings and most of the structural elements of the semi-natural landscapes (like hedges and small water bodies). Because of the resolution, the vertical dimension needs explicit handling to avoid discontinuities incompatible with many applications. For example, how to map a river flowing under a bridge? The particularity of our data is to provide a two-digit land cover code to label all the overlapping items. The identification of all the overlaps resulted from the combination of remote sensing image analysis and decision rules involving ancillary data. The final product is therefore semantically precise and accurate in terms of land cover description thanks to the addition of 24 classes on top of the 11 pure land cover classes. The quality of the map has been assessed using a state-of-the-art validation scheme. Its overall accuracy is as high as 91.5%, with an average producer’s accuracy of 86% and an average user’s accuracy of 91%., SCOPUS: ar.j, info:eu-repo/semantics/published

info:eu-repo/semantics/published

The analysis of surface deformation associated with intruding magma has become an established method to study subsurface processes and intrusion architecture. Active subsurface magmatism induces deformation that is commonly modeled using static elastic models. To what extent, Coulomb failure of the crust affects surface deformation remains, so far, largely unexplored. In this contribution we present quantitative laboratory results of surface deformation induced by the emplacement of simulated dikes and cone sheets in a cohesive Coulomb material. The analysis of the experimental surface deformation shows that these intrusion types produce distinct and characteristic surface deformation signatures, which reflect the evolution of the intrusion at depth. Generally, dikes show a two-phase evolution while cone sheets develop gradually. In comparison, cone sheets induce larger uplifted areas and volumes than dikes relative to the depth of the injection source. Dike formation is, in turn, is likely accommodated, to a larger degree than cone sheets, by lateral opening of the host consistent with our current understanding of dike emplacement mechanics. Notably, only surface uplifts develop above the experimental dikes, consistent with a viscous indenter propagation mechanism, that is, a dike pushing ahead. The measured surface deformation patterns associated with dikes starkly contrast with established static, elastic models that predict local subsidence above the tip of a dike. This suggests that Coulomb failure of crustal rocks may considerably affect surface deformation induced by propagating igneous intrusions. This is especially relevant when a relatively high viscosity magma intrudes a weak host, such as unconsolidated sedimentary and volcaniclastic rocks.

RESUME. Dans un contexte d’urbanisation et d’augmentation des risques des habitants à cause du changement climatique, les autorités doivent élaborer des plans de gestion pour comprendre, mesurer et cartographier les risques. Cet article traite de l'utilisation des géodonnées, des analyses spatiales et de la télédétection pour développer des méthodes de cartographie d’occupation / utilisation du sol mais aussi de densité de population. Ces cartes sont essentielles dans l’analyse des risques, que ce soit dans l’évaluation des dangers ou dans l’exposition de la population mais elles répondent également aux exigences de la directive européenne INSPIRE et donc aux obligations de l’administration. ABSTRACT. In the context of steady urban population growth and increased risk to these populations due to climate change, cities need to develop management strategies to understand, measure, map and mitigate the challenges and risks. This article deals with the use of geodata, spatial analysis and remote sensing to develop land-cover / land-use mapping and population density methods. These maps are not only essential in the risk analysis, whether in the assessment of hazards or in the exposure of the population, but they also meet the requirements of the European directive INSPIRE and therefore the obligations of the administration., info:eu-repo/semantics/published

info:eu-repo/semantics/nonPublished

Risk situation can be mitigated by prevention measures, early warning tools and adequate monitoring of past experiences where Earth Observation and geospatial analysis have an adding value. This paper discusses the potential use of Earth Observation data and especially Land Cover / Land Use map in addressing within the three aspects of the risk assessment: danger, exposure and vulnerability. Evidences of the harmful effects of air pollution or heat waves are widely admitted and should increase in the context of global warming. Moreover, urban areas are generally warmer than rural surroundings, the so-called urban heat island. Combined with in-situ measurements, this paper presents models of city or local climate (air pollution and urban heat island), with a resolution of less than one kilometer, developed by integrating several sources of information including Earth Observation data and in particular Land Cover / Land Use. This assessment of the danger is then be related to a map of exposure and vulnerable people. Using dasymetric method to disaggregate statistical information on Land Cover / Land Use data, the SmartPop project analyzes in parallel the map of danger with the maps of people exposure A special focus on some categories at risk such as the elderly has been proposed by Aubrecht and Ozceylan (2013). Perspectives of the project includes the integration of a new Land Cover / Land Use map in the danger, exposure and vulnerability models and proposition of several aspects of risk assessment with the stakeholders of Wallonia., SCOPUS: cp.p, info:eu-repo/semantics/published

Simulating population distribution and land use changes in space and time offer opportunities for smart city planning. It provides a holistic and dynamic vision of fast changing urban environment to policy makers. Impacts, such as environmental and health risks or mobility issues, of policies can be assessed and adapted consequently. In this paper, we suppose that "Smart" city developments should be sustainable, dynamic and participative. This paper addresses these three smart objectives in the context of urban risk assessment in Wallonia, Belgium. The sustainable, dynamic and participative solution includes (i) land cover and land use mapping using remote sensing and GIS, (ii) population density mapping using dasymetric mapping, (iii) predictive modelling of land use changes and population dynamics and (iv) risk assessment. The comprehensive and long-term vision of the territory should help to draw sustainable spatial planning policies, to adapt remote sensing acquisition, to update GIS data and to refine risk assessment from regional to city scale., SCOPUS: cp.p, info:eu-repo/semantics/published

Subvertical dykes and inclined cone-sheets represent the two main types of magmatic sheet intrusions in volcanic systems. Despite their coexistence in the same volcanoes and seemingly common source, the intrusion dynamics of dykes and cone sheets has often been addressed through distinct models, such that we cannot predict under which condition either of the two forms. We present a series of scaled laboratory experiments that reproduce the emplacement of sheet intrusions into the brittle crust. A cohesive silica flour was used as model crust, and some vegetable oil as a low viscosity magma. The experiments comprised the injection of the oil at constant flow rate into the flour through an inlet. Through 46 experiments, we varied independently the depth (h) and the diameter (d) of the inlet, as well as the injection velocity (v). Our experiments produced sheet intrusions exhibiting either dyke or cone sheet morphologies. Dykes were characterized by a sub-vertical, slightly elliptic shape that often split into two branches to form a "boat"- shaped intrusion at very shallow depths. Cone sheets resembled inverted cones with rims that flattened from depth to the surface. Some of experiments produced hybrid intrusions with a dyke-like lower part feeding complex conical sheet intrusion higher up. Combining our systematic parametric study with a dimensional analysis, we show that the formation of dykes and cone sheets is controlled by two dimensionless parameters. One is geometrical ( 1 = h=d) and the other is dynamical ( 2 = v=Cd), where is the viscosity of the vegetable oil and C the flour cohesion. In a plot of 1 vs. 2, the experiments organise into two distinct fields, separated by a transition line that can be described by a power law. The hybrid intrusions produced in our experiments fall along the transition line in between the dyke and cone-sheet regimes. These results show that at high 1 values, dykes are favoured and originate from magma sources that are relatively

Magmatic ore deposits result from transport and settling of dense sulphide liquid droplets in mafic magma. To understand these processes better, analogue experiments were carried out using dense silicon oil droplets suspended in a viscous aqueous polymer solution. The results indicate that sulphide droplets can be carried in suspension by magma flowing at typical velocities. Due to the large surface tension of the sulphide droplets, coalescence does not occur during transport. Transport ceases when upward magma velocity decreases because of conduit enlargement or change from vertical to horizontal flow. Post-deposition coalescence of droplets is controlled by the magma viscosity and the presence of crystals., Magmatic ore deposits result from transport and settling of dense sulphide liquid droplets in mafic magma. To understand these processes better, analogue experiments were carried out using dense silicon oil droplets suspended in a viscous aqueous polymer solution. The results indicate that sulphide droplets can be carried in suspension by magma flowing at typical velocities. Due to the large surface tension of the sulphide droplets, coalescence does not occur during transport. Transport ceases when upward magma velocity decreases because of conduit enlargement or change from vertical to horizontal flow. Post-deposition coalescence of droplets is controlled by the magma viscosity and the presence of crystals.