Publications of Alexandre Peeters
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See detailL'effet des barrages de castors sur le système hydrographique
Petit, François ULiege; Denis, Anne-Cécile ULiege; Levecq, Yannick ULiege et al

Conference given outside the academic context (2012)

Estimation de la sédimentation dans les retenues provoquées par les barrages de castor. Impact en aval des barrages sur l'incision des rivières. Localisarion des barrages de castor en relation avec la ... [more ▼]

Estimation de la sédimentation dans les retenues provoquées par les barrages de castor. Impact en aval des barrages sur l'incision des rivières. Localisarion des barrages de castor en relation avec la tailled es rivières (ordination des cours d'eau). Discussion sur les conséquences éventuelles des retenues sur les débits d'étiage. [less ▲]

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See detailPilot project « Walphy » : Walloon experimentation of river restoration
Peeters, Alexandre ULiege; Verniers, Gisèle; de le Court, Bernard et al

Conference (2012, April 20)

According to the Water Framework Directive (WFD 2000/60), our rivers and water bodies are required to achieve the “good ecological status” by 2015. This requirement is related to the physico-chemical ... [more ▼]

According to the Water Framework Directive (WFD 2000/60), our rivers and water bodies are required to achieve the “good ecological status” by 2015. This requirement is related to the physico-chemical, biological water quality as well as the hydromorphological quality. In this context, a LIFE Environment project, co-founded by the European Union and the Service Publique de Wallonie, was launched in 2009 for a period of five years. It aims to realize the experimental and demonstrative river restoration works on three “at risk” water bodies, based on two axes: longitudinal continuity and transversal continuity. The first two selected water bodies (Bocq, eastern tributary of the Meuse) are suitable for the restoration works which concern the longitudinal continuity due to the presence of dams and other obstacles between 1 and 3 m high. These works consist in dam management (weir removal or fish ladders) taking into account hydromorphological (bedload transport) and biological (invertebrate or fish species free movement) impacts. The third water body (Eau Blanche, western tributary of the Meuse) presents straightened rivers with artificial banks which consequently lead to poor connections between the stream and its floodplain. This water body is therefore appropriated for the works based on the transversal continuity recovery. These works consist in enhancing straightened river channel and restoring meanders or banks. Until now, these works have been realized on more than 5 km. These works are being monitored on the basis of geomorphological and ecological analysis. The geomorphological monitoring is based on surveys conducted before and after the works. It concerns the bedload transport, the clogging of the gravel layer and the morphological changes of the river following the works. The ecological monitoring is based on two indicators: macroinvertebrates and fishes. Standardized and repeatable methods were developed to compare the situation before and after the works, especially through the analysis of microhabitats. In addition, we use another two complementary indexes of physical quality for this monitoring. Developed by the consulting office Teleos, these indexes have a fish orientation and have been implemented in many of our stations. [less ▲]

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See detailComparison of methods for quantifying active layer dynamics and bedload discharge in armoured gravel-bed rivers
Houbrechts, Geoffrey ULiege; Van Campenhout, Jean ULiege; Levecq, Yannick ULiege et al

in Earth Surface Processes and Landforms (2012), 37

Several methods were employed in the Ardennian rivers (Belgium) to determine the depth of the active layer mobilized during floods and to evaluate the bedload discharge associated with these events. The ... [more ▼]

Several methods were employed in the Ardennian rivers (Belgium) to determine the depth of the active layer mobilized during floods and to evaluate the bedload discharge associated with these events. The use of scour chains has shown that the depth of the active layer is systematically less than the b-axis of the average particle size (D50) of the elements which compose the surface layer of the riffles. This indicates that only a partial transport exists during low magnitude floods. The bedload discharge has been evaluated by combining data obtained using the scour chains technique and the distance covered by tracers. Quantities of sediment transported during frequent floods are relatively low (0 02 t km–2) due to the armour layer which protects the subsurface material. These low values are also related to the fact that the distance calculated for mobilized bedload only applies to tracers fitted with PIT (passive integrated transponder)-tags (diameter>20 mm), whereas part of the bedload discharge is composed of sand and fine gravel transported over greater distances than the pebbles. The break-up of the armour layer was observed only once, for a decennial discharge. During this event, the bedload discharge increased considerably (2 t km–2). The use of sediment traps, data from dredging and a Helley–Smith sampler confirm the low bedload transport in Ardennian rivers in comparison to the bedload transport in other geomorphological contexts. This difference is explained by the presence of an armoured layer but also by the imbricated structures of flat bed elements which increase the resistance to the flow. Finally, the use of the old iron industry wastes allowed to quantify the thickness of the bed reworked over the past centuries. In the Lembrée River, the river-bed contains slag elements up to a depth of about 50 cm, indicating that exceptional floods may rework the bed to a considerable depth. [less ▲]

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See detailMicrohabitats survey used in river restoration
Peeters, Alexandre ULiege; Hallot, Eric ULiege; Houbrechts, Geoffrey ULiege et al

Conference (2011, October 14)

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See detailRestauration hydromorphologique : Les échelles de travail optimales ?
Hallot, Eric ULiege; Peeters, Alexandre ULiege; Verniers, Gisèle et al

Conference (2011, October 03)

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See detailBelgo-Serbian explorations on the massif of Durmitor (Montenegro) since 2008
Peeters, Alexandre ULiege

Poster (2011, May 21)

Abstract: This poster relates the results of the Belgo-Serbian explorations on the massif of Durmitor (Montenegro) since 2008. These explorations were only possible thanks to the Serbian cavers of ASAK ... [more ▼]

Abstract: This poster relates the results of the Belgo-Serbian explorations on the massif of Durmitor (Montenegro) since 2008. These explorations were only possible thanks to the Serbian cavers of ASAK that we met in Lazareva, training camp in Serbia. Thereafter, the Serbian cavers gave us the opportunity of an exploration on the massif of Durmitor. For the Belgian cavers, this exploration was part of the federal training project Explo2009, whose purpose is to train the young cavers underground exploration. Regarding the results of these explorations, this poster details the discovery of the three main caves: Pedina sa ledom pod Bandijerne, l’ébouleuse and Fliš. Pedina sa ledom pod Bandijerne has long been known because of its entry porch which can be seen from the camp. With the discovery of a new passage in the chamber that follows the entrance, the exploration of this new réseau was done by the Serbian cavers in 2008 and was continued by the Belgian cavers in 2009, reaching the depth of 141 m.L’ébouleuse, which is near the Minin Bogaz pass, has been discovered in 2009. It has been completely explored in several days, reaching the bottom of the cave at the depth of 113 m. Last but not least, the main result of these explorations is Fliš. The exploration of this deep cave began in 2009 and is still in progress. The depth of 432 m was reached in 2009 and then 582 m in 2010. This cave is characterized by deep pits in which we can see the sequence of the sedimentary rocks, called Flysch. [less ▲]

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See detailRéhabilitation hydromorphologique : méthodes de suivis géomorphologiques et écologiques
Verniers, Gisèle; Peeters, Alexandre ULiege

Conference (2011, February 03)

Le projet Walphy a pour objectif d'améliorer la qualité écologique de deux masses d'eau, le Bocq et l'Eau Blanche, dans le but de répondre aux exigences de la Directive européenne sur l'Eau (2000/60/CE ... [more ▼]

Le projet Walphy a pour objectif d'améliorer la qualité écologique de deux masses d'eau, le Bocq et l'Eau Blanche, dans le but de répondre aux exigences de la Directive européenne sur l'Eau (2000/60/CE). Suite à une évaluation de la qualité physique du milieu, des travaux d'aménagement sont entrepris suivant 2 axes de réhabilitation : - la continuité longitudinale qui concerne la libre circulation des poissons et des sédiments, - la continuité transversale responsable des échanges du cours d'eau avec ses zones annexes. Ces chantiers - pilotes font l'objet d'un suivi scientifique afin d'analyser les impacts sur l'hydromorphologie (transport des sédiments, diversité des habitats …) et sur l'écologie (végétations, macroinvertébrés et populations piscicoles). Le projet a démarré en janvier 2009, il est co-financé par l'Union Européenne pendant 5 ans. La coordination est assurée par la Direction des Cours d'Eau non Navigables (DCENN - DGARNE) en collaboration avec les Universités de Liège (Laboratoire d'Hydrographie et de Géomorphologie Fluviatile LHGF) et de Namur (Unité de Recherche en Biologie des Organismes URBO). [less ▲]

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See detailÉtude cartographique et projet de restauration sur une rivière rectifiée, l’Eau Blanche
Peeters, Alexandre ULiege; Verniers, Gisèle; Hallot, Eric ULiege et al

Conference (2010, October 04)

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See detailWALPHY : un projet pilote de réhabilitation de cours d’eau
Verniers, Gisèle; Peeters, Alexandre ULiege; Hallot, Eric ULiege et al

Conference (2010, September 20)

Grâce au co-financement de l’Union européenne dans le cadre de la ligne budgétaire LIFE Environnement, un projet pilote sur la restauration physique des cours d’eau a démarré en janvier 2009 pour une ... [more ▼]

Grâce au co-financement de l’Union européenne dans le cadre de la ligne budgétaire LIFE Environnement, un projet pilote sur la restauration physique des cours d’eau a démarré en janvier 2009 pour une durée de 5 ans. Son nom : WALPHY pour « Wallonie – physique ». Le projet est coordonné par la Direction des Cours d’Eau Non Navigables DCENN (Service Public de Wallonie SPW - Belgique) dont le district de Namur assure la réalisation des travaux de restauration. Deux partenaires scientifiques assument l’évaluation et le suivi de ces travaux : le Laboratoire d’Hydrographie et de Géomorphologie Fluviatile de l’Université de Liège et l’Unité de Recherche en Biologie des Organismes des Facultés Universitaires de Namur. [less ▲]

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See detailDesign of a decision tool for hydromorphological restoration of water bodies in Walloon Region
Peeters, Alexandre ULiege; Hallot, Eric ULiege; Verniers, Gisèle et al

Poster (2010, May 05)

The pilot project WALPHY (LIFE + Environment LIFE07 ENV/B/000038, UE-funded) develops a structured approach aiming at improving hydromorphological quality of the upstream Meuse basin in order to achieve ... [more ▼]

The pilot project WALPHY (LIFE + Environment LIFE07 ENV/B/000038, UE-funded) develops a structured approach aiming at improving hydromorphological quality of the upstream Meuse basin in order to achieve the “good ecological status” required by the Water Framework Directive (WFD 2000/60). It began in January 2009 for a period of 5 years. River’s biological recovery needs the recovery of river’s structure and physical dynamics. Returning to "good ecological status" inevitably involves physical restoration of affected rivers. Physical component of aquatic environment acts as a limiting factor for their functioning. Three types of modification are key obstacles for river good ecological status: (i) fluxes alteration (discharge, sedimentation. . . ), (ii) forms alteration (uniform facies. . . ) and (iii) biotopes access alteration (lateral connections breaks, modification of the continuity upstream/ downstream. . . ). Therefore hydromorphology is needed to implement the WFD. To respond to this legal necessity, we develop a unique, useful and suitable methodology in Walloon Region to determine and schedule river physical quality restoration works. This methodology has been applied on 3 “risk water bodies”. The works are based on two axes : longitudinal continuity and transversal continuity. The two first selected water bodies (Bocq river, eastern tributary of the Meuse) seem to be convenient for the restoration works which concern the longitudinal continuity due to the presence of dams and other obstacles usually between 1 and 3 m high. These works consist in dam management (weir removal or fish passage) taking into account hydromorphological (bedload transport) and biological (invertebrate or fish species free movement) impacts. The third water bodies (Eau Blanche river, western tributary of the Meuse) presents straightened rivers with artificial banks, witch consequently own bad connections between the stream and its floodplain. This water bodies should therefore be appropriated for the works based on the transversal continuity recovery. They consist in enhancing straightened river channels, restoring meanders or bank restoration. The first river restoration works will take place from summer 2010. A monitoring has already been undertaken to draw up the situation before the restoration works, witch will be able to compare to the situations during and after works. In addition, a natural site has been chosen to enable any comparison with the intervention sites. The geomorphological monitoring is based on physical and sedimentological parameters (substrate cartography, velocity measures, stream channel DEM, topography and sedimentological index). The ecological monitoring consists in analysing the physical and chemical parameters (turbidity, suspended sediment load). It also analyses the biological quality through 3 indicators: macrophytes, macroinvertebrates and fishes. Among other, a microhabitats method has been improved and applied on 3 intervention sites and 1 natural site. The microhabitats cartography results from both the flow velocity cartography and the substrate cartography. With this method, the physical quality of each intervention site could be compared with the natural site and above all with the future situation. Our method is also useful to inventory precisely invertebrates and to characterise fish habitats. [less ▲]

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See detailStudy of the bedload transport in gravel bed rivers
Houbrechts, Geoffrey ULiege; Hallot, Eric ULiege; Peeters, Alexandre ULiege et al

Conference (2009, July)

Bedload transport has been studied in Ardenne rivers using different methods. Experiments with marked pebbles were carried out on gravel bed rivers in order to determine critical parameters of ... [more ▼]

Bedload transport has been studied in Ardenne rivers using different methods. Experiments with marked pebbles were carried out on gravel bed rivers in order to determine critical parameters of mobilisation. The tracking of more than 1000 elements marked with PIT-tags (Passive Integrated Transponder) has been performed on different sized rivers during three hydrological seasons. These surveys allowed us to determine the initial motion of bed material, to measure the distance of particle travel from flood to flood, to reconstruct the trajectories of pebbles, to analyze the burying of particles into the subsurface layer and to identify the trapping sites and their effects on the bedload progression. On the same rivers, the thickness of the active bed layer has been measured using scour chains. It appears that the mobilised layer thickness increases with specific stream power. Bedload discharge of several floods has also been estimated crossing the active layer thickness and the mean progression distance of marked pebbles. Pits have been dug across the bed of a gravel bed stream (catchment area of 12 km²) in order to trap all particles moving on the bed. Volume of sediments trapped has been measured after each flood event and the largest elements mobilised have been measured. These observations show that bedload trapped is clearly more important that bedload discharge estimated by the method of scour chains and marked pebbles. This difference is for the most part explained by the trapping of sandy matrix from the subsurface layer, which is also moving on the bed. In this headwater stream (forested floodplain), the specific bedload discharge is only 0.4 t.km-1.year-1. Such a value is relatively low in comparison with other Ardenne rivers (up to 2,5 t.km-1.year-1), but may be partly explained by numerous vegetation logjams, which slow down bedload progression and increase bed roughness. [less ▲]

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See detailLa typologie et les caractéristiques hydromorphologiques des cours d'eau wallons
Petit, François ULiege; Hallot, Eric ULiege; Houbrechts, Geoffrey ULiege et al

in Bilan d'une décennie d'ingénierie écologique (2008)

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See detailApport de la dendrochronologie pour l’étude de l’évolution du lit mineur de la Lesse
Van Campenhout, Jean ULiege; Pirard, Xavier; Houbrechts, Geoffrey ULiege et al

Poster (2007, October 10)

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See detailEvaluation de la résistance des aménagements par techniques végétales face aux événements hydrologiques
Peeters, Alexandre ULiege; Hallot, Eric ULiege; Houbrechts, Geoffrey ULiege et al

Poster (2007, October)

Lors du suivi géomorphologique d’aménagement ou de restauration de cours d’eau par techniques végétales réalisé en Région Wallonne, nous nous sommes entre autres intéressés à la résistance que ces ... [more ▼]

Lors du suivi géomorphologique d’aménagement ou de restauration de cours d’eau par techniques végétales réalisé en Région Wallonne, nous nous sommes entre autres intéressés à la résistance que ces techniques offraient face aux différents évènements hydrologiques. Nous avons étudié plusieurs types de techniques (telles que plantations, caissons, épis, peignes et fascines, végétalisation de gabions, techniques combinées...) réalisés sur des rivières de différentes tailles, situées dans des contextes géomorphologiques régionaux variés (impliquant une dynamique différente). La résistance de ces techniques a été évaluée en utilisant la puissance spécifique calculée lors des différentes crues subies par l’aménagement. Cette dernière représente la capacité de travail qu'une rivière peut effectuer et elle permet, ente autres, d'appréhender l'activité des rivières en ce qui concerne les formes et la dynamique des méandres (Ferguson, 1981 ; Bravard, 1991) mais également la possibilité de réaction et d'adaptation des rivières en réponse à des travaux d'aménagement (Brookes, 1998). Les puissances spécifiques ont été calculées non seulement pour le débit à plein bord mais aussi pour la première crue importante survenue après la mise en place du chantier. Par ailleurs, les récurrences des crues ont également été déterminées. Ces premiers résultats nous permettent de proposer une synthèse s’intégrant dans un guide technique (Technique végétales : conception, application et recommandations, GIREA - LHGF) destinés aux différents gestionnaires. BRAVARD J.P., 1991. La dynamique fluviale à l’épreuve des changements environnementaux : Quels enseignements applicables à l’aménagement des rivières ? La Houille Blanche, 7-8, 515-521. BROOKES A., 1988. Channelized rivers, perspectives for environmental management. Wiley, New York, 326 p. FERGUSON R.I., 1981. Channel form and channel changes ; In British Rivers, Lewin J. (Ed), Allen, London,, 91- 125. [less ▲]

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See detailLa Cartographie des Zones Inondées : Approche géomorphologique et Enquêtes de Terrain
Peeters, Alexandre ULiege; Van Campenhout, Jean ULiege; Donnay, F. et al

in Les risques majeurs en Région wallonne : prévenir en aménageant (2006)

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