The exploitation of urban-material spectral properties is of increasing importance for a broad ra... more The exploitation of urban-material spectral properties is of increasing importance for a broad range of applications, such as urban climate-change modeling and mitigation or specific/dangerous roof-material detection and inventory. A new spectral library dedicated to the detection of roof material was created to reflect the regional diversity of materials employed in Wallonia, Belgium. The Walloon Roof Material (WaRM) spectral library accounts for 26 roof material spectra in the spectral range 350–2500 nm. Spectra were acquired using an ASD FieldSpec3 Hi-Res spectrometer in laboratory conditions, using a spectral sampling interval of 1 nm. The analysis of the spectra shows that spectral signatures are strongly influenced by the color of the roof materials, at least in the VIS spectral range. The SWIR spectral range is in general more relevant to distinguishing the different types of material. Exceptions are the similar properties and very close spectra of several black materials, me...
RESUME. Dans un contexte d’urbanisation et d’augmentation des risques des habitants a cause du ch... more RESUME. Dans un contexte d’urbanisation et d’augmentation des risques des habitants a cause du changement climatique, les autorites doivent elaborer des plans de gestion pour comprendre, mesurer et cartographier les risques. Cet article traite de l'utilisation des geodonnees, des analyses spatiales et de la teledetection pour developper des methodes de cartographie d’occupation / utilisation du sol mais aussi de densite de population. Ces cartes sont essentielles dans l’analyse des risques, que ce soit dans l’evaluation des dangers ou dans l’exposition de la population mais elles repondent egalement aux exigences de la directive europeenne 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 analys...
The incised meanders of the Semois Valley, in Southern Ardenne, are remarkably elongated, forming... more The incised meanders of the Semois Valley, in Southern Ardenne, are remarkably elongated, forming a nearly 100-km-long meander belt. Their elongation is conditioned by the relative orientation of the meander loops and the regional slaty cleavage, as theorized by Strahler. These meanders already existed in the Early Quaternary, some cut-off meanders lying more than 100 m above the present floodplain. Although the Quaternary incision rates of the Semois were low (≤0.05 mm/year), several meanders look more entrenched than ingrown, probably because lateral erosion was fairly slow (~0.3–0.5 mm/year), owing to the large quantity of material to evacuate by a rather small river. The combined aesthetic and scientific interests of this particularly well-developed meander belt speak in favour of the preservation of the nicest meanders as geomorphosites.
ISPRS Annals of Photogrammetry, Remote Sensing and Spatial Information Sciences, 2016
Simulating population distribution and land use changes in space and time offer opportunities for... more 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 updat...
Flash floods and muddy floods may cause severe human and material damage despite their small spat... more Flash floods and muddy floods may cause severe human and material damage despite their small spatial extent and low occurrence. In late May 2008, a major event has affected the area of Liège. This paper describes the methodology used to reconstruct the hydrosedimentological parameters of the flood from the geomorphological evidences observed in the field. Bed load and suspended load transport rates estimated during this extreme event were compared to the average values observed in other Walloon rivers and more specifically in the Ardennes Massif. The spatial distribution and the temporal evolution of the flash flood and muddy flood events are then analysed across Wallonia based on several works compiling press archives since the early twentieth century. The biases associated with this type of historical sources and the consequences of flash floods and muddy floods on the vulnerability and the risk of flooding in Wallonia are finally addressed.Les crues éclairs et les coulées boueuse...
Earth observation technologies offer non-intrusive solutions for monitoring complex and risky sit... more Earth observation technologies offer non-intrusive solutions for monitoring complex and risky sites, such as landfills. In particular, unmanned aerial vehicles (UAVs) offer the ability to acquire data at very high spatial resolution, with full control of the temporality required for the desired application. The versatility of UAVs, both in terms of flight characteristics and on-board sensors, makes it possible to generate relevant geodata for a wide range of landfill monitoring activities. This study aims to propose a robust tool and to provide data acquisition guidelines for the land cover mapping of complex sites using UAV multispectral imagery. For this purpose, the transferability of a state-of-the-art object-based image analysis open-source processing chain was assessed and its sensitivity to the segmentation approach, textural and contextual information, spectral and spatial resolution was tested over the landfill site of Hallembaye (Wallonia, Belgium). This study proposes a c...
The cuesta landscape of Belgian Lorraine and Luxembourg’s Gutland belongs to the north-eastern ri... more The cuesta landscape of Belgian Lorraine and Luxembourg’s Gutland belongs to the north-eastern rim of the Paris Basin, characterized by the wide syncline of the Gulf of Luxembourg. Highlighting the underlying geological structure and lithology, the cuestas were progressively sculpted in close relation with the contrasted evolutions of the Meuse and Rhine river systems. The landscape was established during the Cenozoic in Triassic and Jurassic rocks. These are formed of alternating hard pervious and soft, generally impervious units, the latter with a limited resistance to superficial weathering under the climatic conditions of the Neogene and Quaternary. The hard units frequently appear as thick homogenous layers, not only making the core of the cuestas but featuring also many escarpments. Height and lateral extent of the cuestas are controlled by the thickness of the hard layers and lateral changes in facies, as exemplified in the Middle Liassic sandstone and Triassic rocks. Remnant...
The exploitation of urban-material spectral properties is of increasing importance for a broad ra... more The exploitation of urban-material spectral properties is of increasing importance for a broad range of applications, such as urban climate-change modeling and mitigation or specific/dangerous roof-material detection and inventory. A new spectral library dedicated to the detection of roof material was created to reflect the regional diversity of materials employed in Wallonia, Belgium. The Walloon Roof Material (WaRM) spectral library accounts for 26 roof material spectra in the spectral range 350–2500 nm. Spectra were acquired using an ASD FieldSpec3 Hi-Res spectrometer in laboratory conditions, using a spectral sampling interval of 1 nm. The analysis of the spectra shows that spectral signatures are strongly influenced by the color of the roof materials, at least in the VIS spectral range. The SWIR spectral range is in general more relevant to distinguishing the different types of material. Exceptions are the similar properties and very close spectra of several black materials, me...
RESUME. Dans un contexte d’urbanisation et d’augmentation des risques des habitants a cause du ch... more RESUME. Dans un contexte d’urbanisation et d’augmentation des risques des habitants a cause du changement climatique, les autorites doivent elaborer des plans de gestion pour comprendre, mesurer et cartographier les risques. Cet article traite de l'utilisation des geodonnees, des analyses spatiales et de la teledetection pour developper des methodes de cartographie d’occupation / utilisation du sol mais aussi de densite de population. Ces cartes sont essentielles dans l’analyse des risques, que ce soit dans l’evaluation des dangers ou dans l’exposition de la population mais elles repondent egalement aux exigences de la directive europeenne 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 analys...
The incised meanders of the Semois Valley, in Southern Ardenne, are remarkably elongated, forming... more The incised meanders of the Semois Valley, in Southern Ardenne, are remarkably elongated, forming a nearly 100-km-long meander belt. Their elongation is conditioned by the relative orientation of the meander loops and the regional slaty cleavage, as theorized by Strahler. These meanders already existed in the Early Quaternary, some cut-off meanders lying more than 100 m above the present floodplain. Although the Quaternary incision rates of the Semois were low (≤0.05 mm/year), several meanders look more entrenched than ingrown, probably because lateral erosion was fairly slow (~0.3–0.5 mm/year), owing to the large quantity of material to evacuate by a rather small river. The combined aesthetic and scientific interests of this particularly well-developed meander belt speak in favour of the preservation of the nicest meanders as geomorphosites.
ISPRS Annals of Photogrammetry, Remote Sensing and Spatial Information Sciences, 2016
Simulating population distribution and land use changes in space and time offer opportunities for... more 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 updat...
Flash floods and muddy floods may cause severe human and material damage despite their small spat... more Flash floods and muddy floods may cause severe human and material damage despite their small spatial extent and low occurrence. In late May 2008, a major event has affected the area of Liège. This paper describes the methodology used to reconstruct the hydrosedimentological parameters of the flood from the geomorphological evidences observed in the field. Bed load and suspended load transport rates estimated during this extreme event were compared to the average values observed in other Walloon rivers and more specifically in the Ardennes Massif. The spatial distribution and the temporal evolution of the flash flood and muddy flood events are then analysed across Wallonia based on several works compiling press archives since the early twentieth century. The biases associated with this type of historical sources and the consequences of flash floods and muddy floods on the vulnerability and the risk of flooding in Wallonia are finally addressed.Les crues éclairs et les coulées boueuse...
Earth observation technologies offer non-intrusive solutions for monitoring complex and risky sit... more Earth observation technologies offer non-intrusive solutions for monitoring complex and risky sites, such as landfills. In particular, unmanned aerial vehicles (UAVs) offer the ability to acquire data at very high spatial resolution, with full control of the temporality required for the desired application. The versatility of UAVs, both in terms of flight characteristics and on-board sensors, makes it possible to generate relevant geodata for a wide range of landfill monitoring activities. This study aims to propose a robust tool and to provide data acquisition guidelines for the land cover mapping of complex sites using UAV multispectral imagery. For this purpose, the transferability of a state-of-the-art object-based image analysis open-source processing chain was assessed and its sensitivity to the segmentation approach, textural and contextual information, spectral and spatial resolution was tested over the landfill site of Hallembaye (Wallonia, Belgium). This study proposes a c...
The cuesta landscape of Belgian Lorraine and Luxembourg’s Gutland belongs to the north-eastern ri... more The cuesta landscape of Belgian Lorraine and Luxembourg’s Gutland belongs to the north-eastern rim of the Paris Basin, characterized by the wide syncline of the Gulf of Luxembourg. Highlighting the underlying geological structure and lithology, the cuestas were progressively sculpted in close relation with the contrasted evolutions of the Meuse and Rhine river systems. The landscape was established during the Cenozoic in Triassic and Jurassic rocks. These are formed of alternating hard pervious and soft, generally impervious units, the latter with a limited resistance to superficial weathering under the climatic conditions of the Neogene and Quaternary. The hard units frequently appear as thick homogenous layers, not only making the core of the cuestas but featuring also many escarpments. Height and lateral extent of the cuestas are controlled by the thickness of the hard layers and lateral changes in facies, as exemplified in the Middle Liassic sandstone and Triassic rocks. Remnant...
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