- Liège, Liege, Belgium
Eric HALLOT
University of Liege, Géographie, Faculty Member
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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... 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...
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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... 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...
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info:eu-repo/semantics/nonPublishe
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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... 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.
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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... 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...
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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... 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...
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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... 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...
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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... 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...
Research Interests: Geology, Paleontology, Quaternary, Lithology, Neogene, and 4 moreCenozoic, Facies, Fluvial, and Escarpment
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Résumé Dans les schémas départementaux d'aménagement et de gestion des cours d'eau (France), le concept d'espace de liberté des cours d'eau, introduit en 1991, attribue à la rivière un espace de mobilité propre, de... more
Résumé Dans les schémas départementaux d'aménagement et de gestion des cours d'eau (France), le concept d'espace de liberté des cours d'eau, introduit en 1991, attribue à la rivière un espace de mobilité propre, de manière à restaurer la dynamique naturelle d'érosion ...
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Urban planning is a challenge, especially when it comes to limiting land take. In former industrial regions such as Wallonia, the presence of a large number of brownfields, here called “redevelopment sites”, opens up new opportunities for... more
Urban planning is a challenge, especially when it comes to limiting land take. In former industrial regions such as Wallonia, the presence of a large number of brownfields, here called “redevelopment sites”, opens up new opportunities for sustainable urban planning through their revalorization. The Walloon authorities are currently managing an inventory of more than 2200 sites, which requires a significant amount of time and resources to update. In this context, the Sentinel satellites and the Terrascope platform, the Sentinel Collaborative Ground Segment for Belgium, enabled us to deploy SARSAR, an Earth observation service used for the automated monitoring of redevelopment sites that generates regular and automatic change reports that are directly usable by the Walloon authorities. In this paper, we present the methodological aspects and implementation details of the service, which combines two well-known and robust methods: the Pruned Exact Linear Time method for change point det...
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Construire les « Smart Cities » de demain est un enjeu de développement durable tant pour les pouvoirs publics régionaux que locaux. Pouvoir quantifier et localiser précisément la population est important pour la gestion des villes et... more
Construire les « Smart Cities » de demain est un enjeu de développement durable tant pour les pouvoirs publics régionaux que locaux. Pouvoir quantifier et localiser précisément la population est important pour la gestion des villes et l'analyse des risques (pollution, inondations, déchets...). Le projet SmartPop propose de désagréger les statistiques démographiques sur base de la carte d'occupation du sol wallonne (COSW). L'adaptation et la comparaison d'algorithmes de cartographie dassymétrique en Wallonie et en particulier à Liège sont présentées dans ce papier. La calibration et la validation des premiers résultats utilisent des données du Registre National des Personnes Physiques. La cartographie dassymétrique dépend fortement de la qualité et de la précision de la donnée ancillaire. Ce papier illustre l'influence de la rastérisation de cette donnée sur la qualité des résultats dans les centres urbains.
a b s t r a c t. using manual acoustic tracking our study quantified (1) the spatial distribution (2) the movement patterns and (3) the depth preference of adult whitefish, Coregonus lavaretus in a small artificial lake of eastern belgium... more
a b s t r a c t. using manual acoustic tracking our study quantified (1) the spatial distribution (2) the movement patterns and (3) the depth preference of adult whitefish, Coregonus lavaretus in a small artificial lake of eastern belgium were the species was introduced in 1978 for recreational fishing. From June to October 2004, n=6 C. lavaretus (lF 285–519 mm) were tracked (pingers and depth sensor transmitters) from a small boat over periods ranging from 98 to 108 days in Robertville lake (elevation: 490 m; area: 63 ha; max. depth: 47 m). Whitefish were consistently mobile but showed quite variable lake use patterns. t wo individuals traveled the entire length and breadth of the lake, whereas others remained in movement in the deep zone in the middle part of the lake or near the retaining dam wall. Whitefish occupied positions in the water column ranging from 2.6 to 27.0 m (mean 12.7 m ± 5.6 m) that varied depending on individuals. this first study on individual whitefish behavio...
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Cette note avait pour but de déterminer les facteurs environnementaux qui influencent la variabilité spatiale des caractéristiques des débits minimums annuels en Wallonie (Belgique) de 34 rivières, au moyen de deux méthodes... more
Cette note avait pour but de déterminer les facteurs environnementaux qui influencent la variabilité spatiale des caractéristiques des débits minimums annuels en Wallonie (Belgique) de 34 rivières, au moyen de deux méthodes complémentaires : la méthode de classification ascendante hiérarchique et la corrélation linéaire. Les deux méthodes ont été appliquées sur les données transformées par l’analyse en composantes principales. La classification ascendante hiérarchique (méthode de Ward) a mis en évidence l’influence de la lithologie et des activités anthropiques (pompage en eaux souterraines) sur les caractéristiques fondamentales des débits minimums annuels. Les rivières qui drainent un substrat relativement perméable sont caractérisées par des volumes d’écoulement très élevés, une faible variabilité interannuelle de ce volume, une forte variabilité interannuelle de la période d’occurrence et par de faibles valeurs de coefficients d’asymétrie. C’est le contraire pour les rivières qu...
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Résumé L’analyse du transport de la charge de fond de plusieurs rivières du massif ardennais (Belgique) par différentes techniques de marquage de galets (peinture, charge métallique, émetteurs radio) a permis d’identifier le débit... more
Résumé L’analyse du transport de la charge de fond de plusieurs rivières du massif ardennais (Belgique) par différentes techniques de marquage de galets (peinture, charge métallique, émetteurs radio) a permis d’identifier le débit critique où débute le charriage. Pour les rivières les plus importantes (plus de 500 km2), la mise en mouvement se produit à des débits légèrement inférieurs au débit à plein bord (0,7 à 1 Qb), débits qui se présentent en moyenne 5 à 11 jours par an. Pour les rivières de taille intermédiaire (entre 100 et 500 km2), le charriage débute à un débit avoisinant 0,5 fois le débit à plein bord, avec une récurrence de 0,3 an et une durée variant entre 8 et 12 jours par an. Pour les rivières de dimension modeste (moins de 100 km2), la mise en mouvement se produit à des débits compris entre 0,5 et 0,8 Qb, mais leur récurrence est relativement faible et le charriage peut se produire jusqu’à 20 jours par an. Par ailleurs, le transport solide a été évalué à l’aide de p...
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La taille des émetteurs est principalement influencée par la taille de la batterie. En conséquence, plus la durée de fonctionnement est longue, plus volumineux sont les émetteurs. Toutefois, afin de prolonger cette période, ceux-ci ont... more
La taille des émetteurs est principalement influencée par la taille de la batterie. En conséquence, plus la durée de fonctionnement est longue, plus volumineux sont les émetteurs. Toutefois, afin de prolonger cette période, ceux-ci ont été programmés de façon à ne fonctionner que 12 heures par jour. Ainsi, avec un émetteur de 50 mm de longueur et de 15 mm de diamètre, la durée de fonctionnement est d’environ 12 mois. Étant donné la dimension des émetteurs, seuls les éléments de minimum 7 cm de long compétences de crues de différente importance et nous donnent les vitesses de progression par événement hydrologique.
Floods, urban heat islands, mobility issues and other environmental and health risks increase with urban growth. For a sustainable planning of their territory, authorities need operational decision support tools, which can assess short... more
Floods, urban heat islands, mobility issues and other environmental and health risks increase with urban growth. For a sustainable planning of their territory, authorities need operational decision support tools, which can assess short and long-terms impacts of current, intended or optional policies on land-use change. This paper considers the application of a constrained cellular automata land-use change model within both the Walloon and Flanders region in Belgium. Some methodological steps needed for this application are discussed. A national land-use change model is seen as a key asset for sustainable spatial planning. Keywords-land-use change; cellular automata; sustainable spatial planning; risk assessment.
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The achievement of the rivers good ecological status of rivers for 2015 requested by the European Water Framework Directive (WFD 2000/60) led the competent authorities of the Member States to establish the concept of Ecological Quality... more
The achievement of the rivers good ecological status of rivers for 2015 requested by the European Water Framework Directive (WFD 2000/60) led the competent authorities of the Member States to establish the concept of Ecological Quality Status, determined by biological, physico-chemical and hydromorphological elements. To assess the hydromorphological quality of surface waters, homogeneous units of management, called “water bodies” by the authorities, had to be defined. Numerous studies use qualitative and quantitative variables that have proven difficult to transpose, export or compare. Most existing river typologies, often created or adapted in a hurry to meet timing of WFD, are moderately accurate and effective at local scale. Currently, the implementation of operational programs (e.q. restoration works) requires methods to define (i) precisely natural or quasi natural reaches and (ii) catchment-scale homogeneous sectors based on geomorphological and hydrological elements.
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Cities must develop "Smart" management and planning strategies to mitigate the challenges caused by urban population growth. The SmartPop project proposes a LULC model and dasymetric population density maps to Walloon policy... more
Cities must develop "Smart" management and planning strategies to mitigate the challenges caused by urban population growth. The SmartPop project proposes a LULC model and dasymetric population density maps to Walloon policy makers for analyzing and simulating future city development and localization of citizens. In this study, the constrained Cellular Automata LULC change model developed for Flanders and the Brussels-Capital Region is applied to the Walloon Region. This paper presents the first outputs from both parts of the project. On the one hand, maps of current and simulated LULC in 2050, resulting from the the first prototype of the LULC model are presented. Secondly, the dasymetric mapping protocol developed for Flanders is calibrated with Walloon data. The resulting population density map is validated with anonymous data of the National Register of Natural Persons. This project makes use of existing tools and data to propose a common spatial planning model for Wal...
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Variables commonly used to describe the physical habitat of Atlantic salmon Salmo salar L. parr are average velocity, water depth, and substrate. A variety of microand mesohabitat models have been developed using these variables to assess... more
Variables commonly used to describe the physical habitat of Atlantic salmon Salmo salar L. parr are average velocity, water depth, and substrate. A variety of microand mesohabitat models have been developed using these variables to assess habitat quality. However, Atlantic salmon parr live in highly turbulent streams and rivers, in which intense fluctuations of water velocity occur. Laboratory experiments have shown that turbulence affects the behavior and energetics of fish. Nevertheless, habitat use in relation to the strong temporal variability of velocity in natural environments has rarely been studied. In this study, Atlantic salmon parr habitat was examined in relation to turbulence in the Patapedia River, Quebec, Canada. We analyzed meso-habitat use in relation to several dynamic hydraulic variables. Our results revealed that in a natural turbulent condition, parr displayed high individual variability in habitat use in relation to turbulence. Such heterogeneous use of habitat...
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De tout temps, l’agglomeration liegeoise a ete soumise aux inondations liees au debordement de la Meuse avant que des travaux d’amenagement et d’endiguement aient ete entrepris. Cependant, les orages estivaux accompagnes de precipitations... more
De tout temps, l’agglomeration liegeoise a ete soumise aux inondations liees au debordement de la Meuse avant que des travaux d’amenagement et d’endiguement aient ete entrepris. Cependant, les orages estivaux accompagnes de precipitations intenses induisent un depassement de la capacite d’evacuation des reseaux d’egouttage existants. L’etude detaillee de la repartition des interventions effectuees par les services d’incendie et le releve des archives de pompage des stations de demergement mises en place apres la crue de 1926 ont permis de situer les points critiques dans l’agglomeration. En reaction rapide aux precipitations intenses, des sites tels que le boulevard d’Avroy, le plateau de Neupre, la vallee du Geer et le flanc du versant de Cheratte sont regulierement inondes. L’analyse precise quand c’est possible l’origine des debordements et des ruissellements et determine la frequence des inondations qui y ont lieu. Les sites les plus touches, comme le confirment les recentes ino...
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Habitat preferences of Atlantic salmon parr are commonly described using mean flow velocity, water depth, and substrate as habitat variables, and a variety of habitat models have been developed using these variables to predict habitat... more
Habitat preferences of Atlantic salmon parr are commonly described using mean flow velocity, water depth, and substrate as habitat variables, and a variety of habitat models have been developed using these variables to predict habitat quality. However, Atlantic salmon parr live in highly turbulent streams and rivers, in which intense fluctuations of flow velocity occur. Habitat preferences that consider the high variability of flow velocity have not been studied, and this although it has been shown in laboratory experiments that turbulence may affect the behavior and energetics of fish. Consequently, we studied the use of turbulent flow by Atlantic salmon parr in Patapedia River, Quebec, Canada using radio-telemetry. We analyzed summer habitat preferences of individual parr in relation to several dynamic hydraulic variables such as standard deviation of flow velocity, turbulent kinetic energy, Froude number, and shear stress, and compared them with the habitat availability within th...
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In order to assess the hydromorphological quality of surface waters, stakeholders need river typologies accurate and functional enough to be a really efficient management tool. From a typological study based a broad set of... more
In order to assess the hydromorphological quality of surface waters, stakeholders need river typologies accurate and functional enough to be a really efficient management tool. From a typological study based a broad set of hydromorphological field data, we have shown that some variables, like the unit stream power (ω), are particularly appropriate to describe the dynamics of a river. Initial results of repeated measurement in more than 80 sites revealed a regional differentiation based on critical values of stream power at bankfull discharge.
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... Language : English. Author, co-author : Roy, Mathieu [Université de Montréal - UdeM > > > >]. Ovidio ... animale >]. Roy, André [Université de Montréal - UdeM > > > >]. Publication date : May-2005. On... more
... Language : English. Author, co-author : Roy, Mathieu [Université de Montréal - UdeM > > > >]. Ovidio ... animale >]. Roy, André [Université de Montréal - UdeM > > > >]. Publication date : May-2005. On invitation : No. Audience : International. ...
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Dans le Hoyoux, riviere a substratum majoritairement calcaire, la precipitation de carbonates peut se montrer particulierement active. Localement, a la faveur d’irregularites du lit de la riviere ou d’embâcles naturelles, les depots... more
Dans le Hoyoux, riviere a substratum majoritairement calcaire, la precipitation de carbonates peut se montrer particulierement active. Localement, a la faveur d’irregularites du lit de la riviere ou d’embâcles naturelles, les depots prennent progressivement de l’importance ; se developpent alors des barrages de travertin. Ces edifices calcaires, principalement localises dans un secteur particulier du cours d’eau, se retrouvent frequemment regroupes en divers sites adoptant une organisation caracteristique au sein de la riviere. Veritables deversoirs en travers du Hoyoux, les barrages de travertin possedent une certaine influence sur sa dynamique, notamment par les pertes d’energie considerables qu’ils peuvent engendrer. Par ailleurs, l’utilisation de scories siderurgiques rejetees par les etablissements de la vallee, d’une part, et la comparaison d’anciennes illustrations des barrages, d’autre part, permettent d’obtenir des informations quant a l’âge et l’evolution de ces constructi...
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Une methode d'interpretation des donnees granulometriques a ete proposee par Passega (1957 ; 1964) afn de differencier les depots issus de differents modes de transport en milieu fuviatile et marin (suspension uniforme, suspension... more
Une methode d'interpretation des donnees granulometriques a ete proposee par Passega (1957 ; 1964) afn de differencier les depots issus de differents modes de transport en milieu fuviatile et marin (suspension uniforme, suspension gradee, roulage). Elle consiste a utiliser deux centiles caracteristiques (D99 et D50) d'une courbe granulometrique d'un sediment, a les reporter sur un graphique a double echelle logarithmique et a comparer la position du point avec un modele (Image CM) determine sur la base d'echantillons preleves dans des depots pour lesquels les conditions de mise en place sont connues. Plusieurs etudes ont montre que cette methode permettait egalement de differencier les facies sedimentaires en fonction des caracteristiques granulometriques des sediments qui s'y deposent et donc de determiner a posteriori les conditions de sedimentation et de transport des alluvions anciennes. Toutefois, de nombreux parametres specifques a chaque cours d'eau in...