References of "Degré, Aurore"
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See detailRepresenting Grassed Buffer Strips’ Hydrology in a Regional Scale Model
Sohier, Catherine ULg; Degre, Aurore ULg

Conference (2010, April)

In Walloon Region (Belgium), like in many other European countries, riparian buffer strips appear to become one of the most approved nutrient mitigation measures. Within the frame of the water framework ... [more ▼]

In Walloon Region (Belgium), like in many other European countries, riparian buffer strips appear to become one of the most approved nutrient mitigation measures. Within the frame of the water framework directive, policy makers need nutrient mitigation forecasting at the scale of the surface water bodies (from 3 to 426 km² in Wallonia). It induces that the hydrological models have to deal with different designs of the buffers themselves and of their catchment areas. Up to date, most of the studies focused on sediment deposition at field scale. They concluded that the grassed strips can be very effective; nevertheless, the measured effects are still very variable. More often, the way the runoff water passed through the buffer strip (diffused or concentrated flow) is not considered. We adapted our regional hydrological model (physically based, spatially distributed over the 17.000 km² Walloon region (Sohier et al., 2009)) by developing a new “buffer strip subroutine” that identifies automatically the catchment area of all the buffer strips. This is done using a 10 m resolution DTM. The catchment area is then subdivided into an “area of flow concentration” that leads the water to pass through the buffer strip on a very small portion of it and into an “area of diffuse flow” that leads the water to pass through the buffer strip using its whole length. The daily fluxes of water, nutrient and sediments that pass through the buffer are calculated by the model using our dynamic geodatabases (soil, DTM, weather, land use, agricultural practices). Depending on whether the flow is diffused or concentrated the water depth can vary to a large extent; so does the deposition ratio (algorithm adapted from Deletic, 2001). The buffer itself is modelled as grassland without direct fertilisation. Water and nutrient coming from the watershed can be used by the grass, water can infiltrate, evaporate or runoff and denitrification can occur when the soil is saturated. The oral presentation will show our results at the water body level for different buffer strip scenarios considering sediments and nitrate reduction in surface water. [less ▲]

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See detailApproach of regionalization of low flow of the Walloon Region
Gailliez, Sébastien; Degre, Aurore ULg

Poster (2010, April)

The walloon part of the Meuse’s watershed represents 12283 km² and 17694 km of river. The anthropogenic pressure is important (population density is more or less 200 inhabitants/km²). In low flow period ... [more ▼]

The walloon part of the Meuse’s watershed represents 12283 km² and 17694 km of river. The anthropogenic pressure is important (population density is more or less 200 inhabitants/km²). In low flow period, water scarcity can touch both the water users (producer of drinking water and hydropower, tourism and pleasure activities and kayaking) and the river itself affecting the ‘good environmental state’ (context of Water Framework Directive 2000/60/CE). The operational management of rivers during low flow periods needs a deep knowledge of this drought phenomenon including an analysis of low flow severity and its occurrence probability. It also needs the computation of low flow discharge at any point of a river based on available hydrologic variables. The aim of this study is the low flows’ regionalization in the Walloon Region. First of all, the time series of flow data are filled in and validated. The quality is then controlled. The different tests are the determination of the minimum year requirement for a monitoring site, homogeneity tests, verification of presence or absence of summer alga and the proportion of extrapolation of the discharge rating curve Secondly, homogeneous regions will be defined and regression equations will be build. These equations will establish the relation between low flow and physical parameters (watershed area, pedology, slope), climate ones and/or ground water ones. The regression model will permit the computation of low flow discharge at any point of an ungauged river. [less ▲]

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See detailEvaluation of climate changes impact on the hydrological behaviour of the peaty mediums - Application to the Haute Lesse-Ourthe area (Belgium).
Sohier, Catherine ULg; Dautrebande, Sylvia; Degre, Aurore ULg

Poster (2010, April)

The peaty and wet mediums have a very important role to play in term of biodiversity conservation, hydrologic pattern regulation, fauna habitat and landscape value. In the Haute Lesse – Ourthe catchments ... [more ▼]

The peaty and wet mediums have a very important role to play in term of biodiversity conservation, hydrologic pattern regulation, fauna habitat and landscape value. In the Haute Lesse – Ourthe catchments (Saint-Hubert), numbers of these mediums were strongly modified by a drainage network. This drainage network was implemented to permit a forestry production focussed on the Spruce. It has severely disturbed the hydrological cycle. The study consists in modelling the impacts of restoration practices carried out notably within the framework of the LIFE European project on the hydrological behaviour of the peat bog. Then we modelled the effect of climate change. Physical properties and retention curve of peaty materials were characterized on the basis of undisturbed samples using the Richards’apparatus. Calculations were carried out with the hydrological model EPICgrid (GxABT). The model was initially validated on several reference catchments of the study zone. It was then applied at local scale for various peaty mediums (peat type, drainage characteristics, vegetation type) and for current and future climatic conditions. A regional simulation was finally carried out in order to evaluate the impacts of peat bogs restoration measures at catchment scale. Simulations highlighted the differences in physical and hydrous properties of the different peat types (“true” peat and “degraded” peat). Local and regional impacts of peat bogs restoration on their hydrological behaviour have been evaluated. Eventually, simulations allowed us to evaluate climate change’s impact on the hydrological behaviour of the peaty mediums. The model showed notably that future climatic conditions could generate severe droughts which can become critical in some situations. [less ▲]

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See detailEcoulement de l'eau dans les sols
Degre, Aurore ULg

Learning material (2010)

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See detailAssessing structure potential in soil and water conservation: monitoring top soil hydrology from micro to field scale.
Kummert, Nora ULg; Beckers, Eléonore ULg; Roisin, Christian et al

in Wollesen de Jonge, Lis; Moldrup, Per; Lindblad Vendelboe, Anders (Eds.) 1st international conference and exploratory workshop on soil architecture and physico-chemical functions "CESAR" (2010)

Soil structure is a key parameter influencing erosion and water transfers. This paper describes an experiment that covers different aspects of soil structure. Three tillage systems are tested: reduced ... [more ▼]

Soil structure is a key parameter influencing erosion and water transfers. This paper describes an experiment that covers different aspects of soil structure. Three tillage systems are tested: reduced tillage, and two ploughing systems. At micro-scale, analyses are tomography which study images to determine porosity characteristics (connectivity, size, number…) and pF curves where total available water and effective porosity are deducted. At field scale, soil losses and runoff are collected and measured after rainfall simulation on plots for the different tillage systems. The comparison of the results for both scales shows the links between phenomenons at those scales. [less ▲]

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See detailModelling the effects of the current policy measures in agriculture: an unique model from field to regional scale in Walloon region of Belgium
Sohier, Catherine ULg; Degre, Aurore ULg

in Environmental Science & Policy (2010), 13(2010), 754-765

Diffuse nutrient loss from agriculture into the soil, groundwater and surface water affects their quality. Different policies are in force throughout the European Union aiming for their limitation. They ... [more ▼]

Diffuse nutrient loss from agriculture into the soil, groundwater and surface water affects their quality. Different policies are in force throughout the European Union aiming for their limitation. They were implemented through action plans on a regional scale. Hydrological modelling can be a powerful method for efficiently evaluating their effectiveness. In order to be useful whatever the action and for every reporting unit (whole Region, water bodies, nitrate vulnerable zones, fields...) the model must be physically based, it must simulate water and nutrient fluxes in the root zone and the vadose zone as well as being geographically flexible. This paper presents such a model and its application in the context of Wallonia (Southern part of Belgium). It also presents a calculation of what water and nutrient flows could be under a given climatic scenario until 2015. In Belgium, water quality depends upon Regions. Wallonia implemented the European Nitrate Directive through two action plans the first in 2002 and the second in 2007. These actions plans were modelled and compared to a scenario without any modification in the farmers’ practices. The modelling showed the need for two indicators: nitrate concentration under the root zone as fast indicator of the actions’ efficiency and transfer time from surface to groundwater table. The first action plan hardly modified farmers’ field practices and consequently it did not impact water quality. The second action plan had more impact (reduction up to 10 mg/l NO3 under the root zone). It was mainly due to catch crop introduction in the nitrate vulnerable zone, if they are followed by a reduction of the mineral fertilisation (not mandatory). Our results show that new actions are necessary. We show where and to what extent they have to be implemented. Nevertheless, the greatest variation in nitrate leaching from the root zone seems to be dependent on the weather, more than the action plans. Particularly the rainy period between 1998 and 2002 had a huge impact on nitrogen flows. Our hydrological modelling is showed to be a powerful tool of nitrogen management in a still uncertain climatic evolution context. Finally, we showed that patience and perseverance will be necessary to reach the targets of the WFD in the Walloon context. The map of transfer time shows that 8% of the groundwater bodies need over 15 years to be impacted by mitigation measures. [less ▲]

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See detailMesure et spatialisation des précipitations
Degre, Aurore ULg; Hirtt, Laura ULg; Beckers, Eléonore ULg

Learning material (2010)

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See detailHydrologie générale : le bassin versant
Degre, Aurore ULg; Hirtt, Laura ULg; Beckers, Eléonore ULg

Learning material (2010)

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See detailHydrological modeling of the EU Nitrates Directive Actions Programme:
Sohier, Catherine ULg; Dautrebande, Sylvia; Degre, Aurore ULg

Poster (2009, December 11)

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See detailCartographie numérique des zones à risque de ruissellement et d'érosion des sols en Région wallonne
Demarcin, Pierre ULg; Degre, Aurore ULg; Smoos, Augustin et al

Report (2009)

Les exemples de dégâts liés aux inondations par ruissellement et aux coulées de boue ne manquent pas dans l’actualité récente. Les causes sont souvent des conjonctions de facteurs tels que le type de sol ... [more ▼]

Les exemples de dégâts liés aux inondations par ruissellement et aux coulées de boue ne manquent pas dans l’actualité récente. Les causes sont souvent des conjonctions de facteurs tels que le type de sol, l’occupation du sol, la topographie mais aussi bien sur l’événement pluvieux. Sur ce dernier point, il est impossible d’agir. Mais pour les autres, le projet ERRUISSOL fournit les données spatiales nécessaires à une bonne gestion des bassins versants et ce dès l’amont. C’est en effet dès aujourd’hui que des politiques d’adaptation aux changements climatiques annoncés doivent se mettre en place et c’est dès la production du ruissellement et de l’érosion sur les versants agricoles qu’il est possible et nécessaire d’agir pour limiter les conséquences des pluies très intenses. La connaissance spatialisée de notre territoire est dès lors indispensable et les données présentées dans le présent rapport en sont des outils précieux de gestion. Trois types de risques sont cartographiés : le risque de ruissellement diffus, le risque de ruissellement concentré et le risque d’érosion diffuse. Les données couvrent l’ensemble de la Région, avec une résolution au sol de 10 mètres. La méthode de cartographie qui a été utilisée est pragmatique. Elle s’appuie sur les meilleures données disponibles aujourd’hui : la carte numérique des sols et la carte numérique d’occupation des sols, toutes deux mises en œuvre par la DGARNE et la FUSAGx ainsi que les données topographiques les plus récentes, notamment les données du PICC produites par la Région wallonne. Les méthodologies appliquées dans ce projet ont fait l’objet d’une importante réflexion pour la mise au point et la validation des cartes lors d’études pilotes antérieures et lors de nombreuses validations de terrain. Le projet ERRUISSOL s’appuie également sur des modèles les plus pertinents aujourd’hui à l’échelle de la Région wallonne. Ces données cartographiques sont destinées à un large panel d’utilisateurs, pour les aider dans leurs tâches de recherche, d’étude et de gestion. Elles sont utiles pour la réalisation d’études d’incidences préalables à une modification d’affectation du sol ou à l’analyse de problèmes hydrologiques existants en vue d’y remédier. Les exemples ne manquent pas. Enfin, il est important de signaler que la Région wallonne met gratuitement à disposition ces données pour toute étude ou projet d’utilité publique, sur simple demande, moyennant la signature d’une licence d’utilisation. [less ▲]

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See detailFrom Root Zone Modelling To Regional Forecasting Of Nitrate Concentration In Recharge Flows - The Case Of The Walloon Region (Belgium)
Sohier, Catherine ULg; Degre, Aurore ULg; Dautrebande, Sylvia

in Journal of Hydrology (2009), 369(3-4), 350-359

In order to model the nitrate concentration of the recharge water in a spatially distributed way for the agricultural areas of the Walloon Region of Belgium, the EPIC model was first adapted to the ... [more ▼]

In order to model the nitrate concentration of the recharge water in a spatially distributed way for the agricultural areas of the Walloon Region of Belgium, the EPIC model was first adapted to the specific soil description by modifying the reservoir sizes. It was also adapted to the regional crop production by modifying classcrop files in relation with observed data (both aerial and underground crop growth, yield) in wheat, sugar beet, and potato fields. As the vadose zone presents a depth between 1.5 and 104 m in this region, new reservoirs were added according to the geological descriptions available. Deep nitrate transfer was validated in a specific site where cropping history was known. Nitrate nitrogen after harvest in the root zone was validated for wheat within different crop rotations using the first results of a nitrate-monitoring program planned by the authorities to test the effectiveness of the mitigation measures in agriculture. This extended model was also linked to a GIS (geographical information system) using 1 km2-cells. All the required data were rasterised to allow HRU (hydrological response unit) identification within the cells. The cell’s daily water flows are weighted flows of each HRU depending on their relative area within the cell. Water balances at catchment scale allow us to validate the calculation. Taking into account the evolution of distributed land use and observed climatic data, we have built maps of fast indicators and long-term indicators. The first map represents nitrate concentration in the water leaving the root zone and the second one represents the time transfer for nitrate from 1.5 m depth to the groundwater table and nitrate concentration in recharge water. These maps constitute major tools for nitrogen management at a regional level. [less ▲]

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See detailApproche de la régionalisation des débits d'étiage en Région wallonne
Gailliez, Sebastien; Degre, Aurore ULg

in Etiages, sécheresses, canicules rares et leurs impacts sur les usagers de l'eau (2009)

The operational management of rivers during low flows periods needs a best knowledge of the hydrological processes involved. Therefore a study aiming at the regionalization of low flows discharges in the ... [more ▼]

The operational management of rivers during low flows periods needs a best knowledge of the hydrological processes involved. Therefore a study aiming at the regionalization of low flows discharges in the Walloon Region has been started. Its first objective is to characterise the lowest flows throught existing monitoring network. Homogeneous regions will be defined on the basis of the results obtained. For each one, regression equations will be build in order to permit the computation of low flow discharge at any point of an ungauged river. [less ▲]

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See detailERRUISSOL
Degre, Aurore ULg

Learning material (2009)

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See detailProjet ERRUISSOL ou la cartographie des zones à risque de ruissellement et d’érosion en Région wallonne (Belgique)
Demarcin, Pierre ULg; Smoos, Augustin; Dautrebande, Sylvia et al

in Schwartz, Dominique (Ed.) Actes des 10èmes Journées d'étude des sols (2009)

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See detailRoof storage systems: Modelling and performance’s comparison
Beckers, Eléonore ULg; Degre, Aurore ULg

Poster (2008, September)

Rainwater runoff problems have become critical in large cities because of the increasing imperviousness of surfaces. Best practices to manage urban runoff improve water infiltration and evaporation ... [more ▼]

Rainwater runoff problems have become critical in large cities because of the increasing imperviousness of surfaces. Best practices to manage urban runoff improve water infiltration and evaporation through green areas establishment and, therefore, natural hydrological cycle restoration. The aim is to evaluate rainwater runoff from different types of roof storage systems and to conclude about their own interests to manage urban runoff production. [less ▲]

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See detailSoil physical fertility: thesis project for water-soil-plant model improvement
Beckers, Eléonore ULg; Degre, Aurore ULg

Poster (2008, January)

Quantities of nutrients like N, P and K in the soil are generally assumed to be the more important parameters of its fertility. The physical fertility of the soil such as water holding capacity, hydraulic ... [more ▼]

Quantities of nutrients like N, P and K in the soil are generally assumed to be the more important parameters of its fertility. The physical fertility of the soil such as water holding capacity, hydraulic conductivity…is often ignored. The present thesis project purposes the development of a physically-based model linking agricultural practices and changes on soil physical properties. [less ▲]

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See detailStatistique des extremes dans les bassins faiblement jauges: application d'un modele global pluie-debit a cinq bassins versants en region wallonne (Belgique).
Degre, Aurore ULg; Dautrebande, Sylvia; Sohier, Catherine ULg et al

in Biotechnologie, Agronomie, Société et Environnement = Biotechnology, Agronomy, Society and Environment [=BASE] (2008), 12(4), 379-391

The RS-PDM© model generates flows in time series on the basis of observed rainfall after self-calibration which is based on short period of observed rainfall and flow. This is done with daily or hourly ... [more ▼]

The RS-PDM© model generates flows in time series on the basis of observed rainfall after self-calibration which is based on short period of observed rainfall and flow. This is done with daily or hourly data. The study highlights the capacity of the RS-PDM© model to simulate extreme flows in poorly gauged basins in Walloon region on the basis of observed rains and of a short period of observed flows. Concerning the time series, it was highlighted an important dispersion of the flows simulated for a given observed flow even for daily or hourly data. The Nash criteria varied between 0.59 and 0.92. However, the flows simulated via RS-PDM© make it possible to adjust a statistical distribution of extremes flows (Gumbel law) close to the statistic obtained with a long period of gauging. So, if the simulations realized by mean of this model present poor to acceptable performances concerning the time series simulations, they permit to obtain rapidly quite good statistics of extremes flows on the basis of a short gauging period. [less ▲]

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See detailHydrologie générale
Degre, Aurore ULg

Learning material (2008)

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See detailHydraulic behaviour of greened porous pavements: a physical study
Straet, Frederic; Beckers, Eléonore ULg; Degre, Aurore ULg

(2008)

Detailed reference viewed: 56 (17 ULg)