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See detailL’hydrologie, une partenaire de la géomorphopédologie pour une gestion transéchelle des grands enjeux environnementaux
Degre, Aurore ULg; Sohier, Catherine ULg; Colard, François ULg et al

Conference (2010, November 24)

La zone insaturée du sol et du sous-sol est souvent qualifiée de zone critique, étant donné son rôle d’interfaçage entre les compartiments aérien et souterrain de notre environnement. Dans les thématiques ... [more ▼]

La zone insaturée du sol et du sous-sol est souvent qualifiée de zone critique, étant donné son rôle d’interfaçage entre les compartiments aérien et souterrain de notre environnement. Dans les thématiques du transfert des solutés ou de la conservation des eaux et des sols, les recherches d’hydrologie et d’hydraulique agricole s’appuient sur les informations pédologiques et ce depuis une échelle extrêmement locale jusqu’à la vision régionale de la gestion environnementale. Le rôle des descriptions pédologiques dans la gestion et la protection des ressources naturelles est donc majeur. La dérivation des paramètres hydrodynamiques depuis les descriptions pédologiques des sols permet à l’hydrologue de quantifier et de représenter spatialement la dynamique des échanges eau-sol-végétation-atmosphère, les déplacements de l’eau dans le sol et la vadose ainsi que les déplacements et les transformations des solutés. L’hydrologue en retire des indicateurs de pression sur les ressources hydriques de surface et souterraine. Il calcule des flux d’eau, de nutriments et de sédiments à un pas de temps très fin et durant de longues périodes (plus de 30 années). Les recherches présentées ici couvrent la modélisation hydrologique physiquement basée à l’échelle régionale qui vise l’analyse prospective (au-delà de 2020) des mesures envisagées pour limiter les pollutions diffuses d’origine agricole, tout comme des modélisations physiques détaillées en sites expérimentaux. L’érosion hydrique des sols est un autre un enjeu majeur de gestion environnementale. Le sol étant une ressource peu renouvelable, les techniques de conservation des sols et l’aménagement hydraulique des bassins versants ruraux nécessitent la plus grande considération. Elles sont un outil supplémentaire de limitation des apports au cours d’eau (tant en termes de sédiments qu’en termes de nutriments). Là encore, les descriptions pédologiques permettent de cibler les sols les plus sensibles. De plus, les cartes des sols qui incluent une interprétation géomorphologique permettent de confronter les modèles d’arrachement, de transport et de dépôt de sédiments aux observations des pédologues faites lors des premiers levés et actuellement en cours. Ces observations de terrain, réalisées à plusieurs dizaines d’années d’intervalle, constituent un gisement de données précieux et quasiment unique pour la validation des modèles hydrologiques de perte en sol et de dépôt et en vue de l’étude morphodynamique des bassins versants. Il reste actuellement des besoins en termes de description pédologique. Ils ont trait à la caractérisation plus fine de certains sigles, où l’introduction d’éléments relatifs à la dynamique des flux pourrait s’avérer pertinente. Toutefois, on peut constater que dans le contexte actuel et crucial de préservation des ressources eau et sol, l’hydrologie et la science du sol sont réaffirmées comme des partenaires forts de gestion des grands enjeux environnementaux. [less ▲]

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See detailModélisation de la pollution agricole diffuse vers les eaux de surface et souterraines: le projet QualVados
Degre, Aurore ULg; Sohier, Catherine ULg

Scientific conference (2010, October 21)

La pollution diffuse issue de l’agriculture est une donnée majeure de la gestion durable des ressources en eau. Elle doit prendre en compte tant les variables environnementales (Sol, sous-sol, relief ... [more ▼]

La pollution diffuse issue de l’agriculture est une donnée majeure de la gestion durable des ressources en eau. Elle doit prendre en compte tant les variables environnementales (Sol, sous-sol, relief, météo) que les modes de gestion de l’espace (occupation du sol, pratiques agricoles). Le modèle EPICgrid est un modèle hydrologique distribué et physiquement basé qui a été développé à cette fin par l’unité d’Hydrologie et Hydraulique agricole de Gembloux Agro-Bio Tech. Il permet la quantification des pertes d’azote tant vers les eaux de surface que vers les eaux souterraines et couvre toute la Wallonie. Depuis 2006, le projet QualVados (qualité de la zone vadose) a permis d’importants développements visant à prendre en compte notamment les nouvelles réglementations (PGDA et MAE) et les nouvelles données disponibles (COSW et campagnes APL). Des simulations prospectives de la qualité des ressources en eau ont été menées jusqu’aux différentes échéances de la Directive cadre sur l’eau. L’exposé synthétisera les nouveaux développements et les enseignements issus de ces modélisations. [less ▲]

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See detailUtilisation de la CNOSW en tant que carte d'occupation du sol dans le modèle EPICgrid
Sohier, Catherine ULg; Degre, Aurore ULg

Poster (2010, October 20)

Le modèle EPICgrid est un modèle hydrologique distribué de résolution 1km² couvrant toute la Wallonie. Il a été développé par Gx-ABT afin d’évaluer les flux d’eau, de nutriments et de sédiments vers les ... [more ▼]

Le modèle EPICgrid est un modèle hydrologique distribué de résolution 1km² couvrant toute la Wallonie. Il a été développé par Gx-ABT afin d’évaluer les flux d’eau, de nutriments et de sédiments vers les eaux de surface et vers les eaux souterraines. Il permet, entre autres, de tester l’impact de scénarios de gestion des nutriments sur la qualité des eaux en Région wallonne ainsi que des rapportages à différentes échelles dont les masses d’eau de surface. Le modèle requiert parmi ses données d’entrée une cartographie de l’occupation du sol. Dans un premier temps, la carte d'occupation des sols utilisée était issue du projet CARHY (Laime et Dautrebande, 1995) et reposait sur l'analyse d'images satellitaires Landsat pour refléter l’occupation du sol des années '90. En 2009, la CNOSW a été implémentée dans le modèle pour affiner spatialement et mettre à jour cette donnée en vue de simulations hydrologiques prospectives. Pour ce faire, les différentes classes de la CNOSW (niveau 5) ont été complétées au niveau des zones non cadastrées afin d’obtenir une couverture continue, hydrologiquement valide, de toute la Wallonie. Les classes ont ensuite été regroupées en classes hydrologiques d’occupation du sol (7 classes). La comparaison des cartes d’occupation du sol CARHY et issue de la CNOSW montre une répartition en classes similaire au niveau régional. Néanmoins, au niveau local, les différences marquées peuvent être constatées. Les zones urbaines sont également mieux représentées par la CNOSW. L’introduction de la CNOSW dans le modèle EPICgrid en apportant une spatialisation plus précise des occupations du sol a permis d’affiner les résultats du modèle et d’ouvrir de nouvelles pistes de développement telles que la représentation dans le modèle hydrologique du fonctionnement des bandes enherbées riveraines et inter-parcellaires. [less ▲]

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See detailHydrologic modelling and dendrochronology as tool of site-species adequation assessment in a changing climate context
Sohier, Catherine ULg; Debruxelles, Jérôme ULg; Brusten, Thomas ULg et al

Poster (2010, September 21)

A hydrologic model is related to dendrochronological measurements performed in a 52 years old Spruce stand. The site is situated on a hillside with shallow and acid brown soil in the ecoregion of Ardenne ... [more ▼]

A hydrologic model is related to dendrochronological measurements performed in a 52 years old Spruce stand. The site is situated on a hillside with shallow and acid brown soil in the ecoregion of Ardenne (Wallonia, Southern Belgium). Hydrologic modelling The hydrologic simulation runs from 1971 to 2005 at daily time step. The model is based on an EPIC code, adapted to the site concerning soil reservoirs depth, characteristic water contents, root profile and water uptake. Weather data come from the Royal Meteorological Institute. Outputs from the model are real evapotranspiration, surface runoff; interflows, deep percolation and soil moisture at daily time step. Dendrochronological study Tree ring thickness is measured on 24 core samples extracted from 12 dominant trees of the stand. Annual increments are standardised by the ARIMA function in order to produce the annual deviation of ring thickness. Means of annual deviation for the 12 trees are then related to annual soil drought intensities. Results Years 1976 and 1996 are emphasised by both the modelling outputs and the dendrochronological measurements as very dry. Model shows a severe drought and tree ring shows a very low growth. Years like 1990, 1992, 1994 and 2004 shows a less severe drought event but a drought that occurs in June-July, which seems to penalize spruce’s growth. On the other hand, years 1981 and 1998 show an important growth and a high value of mean soil moisture during June and July. The poster will show how the time evolution of the ARIMA index is related to some meaningful hydrologic indexes. These considerations will allow us to progress towards forecasting forest trees reaction to climate events and change. With this in mind, we will use a climate scenario build up in the frame of the AMICE interreg project. [less ▲]

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See detailAnalysis of climate change, high-flows and low-flows scenarios on the Meuse basin: WP1 report - Action 3
Drogue, G.; Fournier, M.; Bauwens, Alexandra ULg et al

Report (2010)

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See detailInondations en aval : quelles aides peuvent fournir les zones humides en amont?
Degre, Aurore ULg; Sohier, Catherine ULg

Conference given outside the academic context (2010)

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See detailSpatial interpolation of daily rainfall in Ourthe and Ambleve Basins, Belgium
Ly, Sarann ULg; Sohier, Catherine ULg; Charles, Catherine ULg et al

in Geophysical Research Abstracts (2010, May)

Spatial interpolation of precipitation data is of great importance for hydrological modelling. The methods of geostatistics (krigings) become more popular to make spatial interpolation from point ... [more ▼]

Spatial interpolation of precipitation data is of great importance for hydrological modelling. The methods of geostatistics (krigings) become more popular to make spatial interpolation from point measurement to distributed hydrological models. However, most of existing geostatistic algorithms are available only for single-moment data. The first step of Kriging computation is the semi-variogramme modelling which usually uses only one variogramme model for all-day data. The objective of this paper is to review the implementation of an algorithm of spatial interpolation methods for daily rainfall and to compare the results of geostatistic and deterministic approaches. In this study, we will use daily rainfall data from 70 rain gauges in the hilly landscape of Ourthe and Ambleve Basins in Belgium (2751 km2). This area lies between 35 and 690 m in elevation and consists of river networks which are the tributaries of the Meuse River. The proposed algorithm will use the method of Cressie’s Approximate Weighted Least Squares to fit among sevens semi-variogramme models (logarithmic, power, exponential, Gaussian, rational quadratic, spherical and penta-spherical) to daily sample semi-variogrammes. These seven models are computed on a daily basis. Firstly, one model is chosen by considering the minimum of least squares coefficient. Secondly, if the chosen model gives negative interpolated values, other models will be chosen again until the result become positive. Cross validation will be used to compare the interpolation performance of geostatistic to deterministic methods usually known as Thiessen polygon and Inverse DistanceWeighting (IDW). [less ▲]

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See detailHow Climate Change Could Affect The Hydrology In Walloon Region ?
Bauwens, Alexandra ULg; Sohier, Catherine ULg; Degre, Aurore ULg

Poster (2010, April 22)

Research on climate change and its impacts on hydrology are increasingly important nowadays. AMICE project focuses on the adaptation of the Meuse to the impacts of climate change. On this study, we focus ... [more ▼]

Research on climate change and its impacts on hydrology are increasingly important nowadays. AMICE project focuses on the adaptation of the Meuse to the impacts of climate change. On this study, we focus on the Walloon tributaries of the Meuse river, and more specifically on the Vesdre and the Lesse sub-catchments. Climate change scenarios are outputs of the CCI-HYDR Perturbation Tool for time slice 2020-2050 and 2070-2100. This tool allows us to build climate change time series and to use it as input of our hydrological models. The most pessimistic and the most optimistic scenarios are selected. The hydrological model used is called EPICGrid and it is a physically based distributed model at catchment scale. EPICGrid used the perturbed meteorological data to provide hydrograms for the different scenarios and time slice for the Vesdre and the Lesse sub-catchments. It appears that for the Vesdre daily discharge with a return period of 100 years (Qd100) could varies between -3% and +27% when the mean annual 7-day Minimum flow with a return period of 50 years (MAM750) varies between -37% and +16% for 2070-2100. For the Lesse, Qd100 varies between -30% and +50% when MAM750 varies between -21% and +28% for 2070-2100. The broad range of discharge variations reflects the broad range of meteorological variation. These results will be used further in the AMICE project to build an adaptation strategy. [less ▲]

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See detailHydrological modelling of the EU Nitrates Directive Actions Programme: new developments in the Walloon Region (Belgium)
Sohier, Catherine ULg; Dautrebande, Sylvia; Degre, Aurore ULg

Poster (2010, April)

Wallonia (Southern Region of Belgium) implemented the Nitrates Directive through a first actions plan in 2002 followed by a second action plan in 2007. It designated vulnerable zones and introduced ... [more ▼]

Wallonia (Southern Region of Belgium) implemented the Nitrates Directive through a first actions plan in 2002 followed by a second action plan in 2007. It designated vulnerable zones and introduced various mandatory practices in order to reduce the nitrate contamination risk. At the same time, the government decided to fund non mandatory practices focused on agro-environment. Some of these (like buffer strips) should also be useful in nutrient mitigation. In order to assess the global effectiveness of all the mitigation practices, we have been developing a hydrological model spatially distributed using a 1km² grid cell on the whole Region (16 900 km²). The EPICgrid model represents the root zone and the vadose zone. In Wallonia, groundwater tables are more than 30 m deep in 8% of the territory. It is therefore of major importance to fill the gap between the root zone and the groundwater bodies. It allows us to assess the nitrate transfer time and forecast the mitigation measures’ effect in time, space and amplitude. On the ground, runoff and sediment yield are modelled at the small watershed scale in order to assess buffer strips’ effect on sediment deposition and its consequences on N and P mitigation. The poster will explain the more recent results that consist in forecasting action plans’ effect until 2015 (on both surface water bodies and groundwater bodies) and modelling of the current buffer strips’ effect. [less ▲]

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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 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 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 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 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 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 detailProjet QualVados : Evaluation des mesures prises pour réduire les incidences de la pollution diffuse d’origine agricole et domestique sur la qualité des masses d’eau de surface et souterraines de la Région wallonne à l’aide du modèle EPICgrid
Sohier, Catherine ULg; Dautrebande, Sylvia; Degre, Aurore ULg

Report (2008)

Wallonia (Southern Region of Belgium) implemented the Nitrates Directive through a first actions plan in 2002 followed by a second action plan in 2007. It designated vulnerable zones and introduced ... [more ▼]

Wallonia (Southern Region of Belgium) implemented the Nitrates Directive through a first actions plan in 2002 followed by a second action plan in 2007. It designated vulnerable zones and introduced various mandatory practices in order to reduce the nitrate contamination risk. . In Wallonia, nitrate-related problems are obvious in several groundwater bodies and their trends over the past 30 years are worrying. The main part of the contamination level is due to agricultural diffuse pollution. Nevertheless, some pollution peaks are observed mainly coming from domestic sewage. In order to assess the global effectiveness of all the mitigation practices, we have been developing a hydrological model spatially distributed using a 1km² grid cell on the whole Region (16 900 km²). The EPICgrid model represents the root zone and the vadose zone. In Wallonia, groundwater tables are more than 30 m deep in 8% of the territory. It is therefore of major importance to fill the gap between the root zone and the groundwater bodies. It allows us to assess the nitrate transfer time and forecast the mitigation measures’ effect in time, space and amplitude. On the ground, runoff and sediment yield are modelled at the small watershed scale. This report presents an complete analysis of the mitigation measures implemented in Wallonia and their effects forecasted until 2015. [less ▲]

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See detailBilan et évolution de la qualité des eaux et des pratiques agricoles en Région wallonne - Chapitre 6 : prévision de l'évolution future
Sohier, Catherine ULg; Dautrebande, Sylvia; Degre, Aurore ULg

Report (2008)

Les premières mesures mises en place en Région wallonne à la suite de la parution de la Directive Nitrate datent de 1994. En 2002, une première version du Plan de gestion durable de l’azote en agriculture ... [more ▼]

Les premières mesures mises en place en Région wallonne à la suite de la parution de la Directive Nitrate datent de 1994. En 2002, une première version du Plan de gestion durable de l’azote en agriculture a été publiée et progressivement mise en place en Région wallonne. Ces mesures visent à limiter la concentration en nitrate de l’eau quittant la zone racinaire, ce nitrate sortant de la zone de prélèvement par les végétaux est un facteur de pression sur la qualité de l’eau. Une fois transféré hors de la zone racinaire, le nitrate peut, selon les caractéristiques pédologiques, géologiques et hydrodynamiques locales rejoindre les eaux de surface ou les eaux souterraines avec un temps de retard extrêmement variable. Dans ce travail, la prévision de la qualité des eaux en Région wallonne sera abordée d’une part en termes de qualité de l’eau quittant la zone racinaire et d’autre part en terme de temps de transfert jusqu’aux eaux souterraines (masses d’eau souterraine supérieures). Pour modéliser l’ensemble des processus décrit ci-dessus, l’unité d’Hydrologie et d’Hydraulique agricole de la Faculté universitaire des Sciences agronomiques de Gembloux avec l’aide de la Région wallonne développe depuis plusieurs années un modèle de simulation hydrologique EPICgrid. [less ▲]

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See detailNitrogen leaching forecasting: modelling and measurements
Sohier, Catherine ULg; Vandenberghe, Christophe ULg; Dautrebande, Sylvia et al

in Bruthans, Jiri; Kovar, Karel; Hrkal, Zbynek (Eds.) International Interdisciplinary Conference on Predictions for Hydrology, Ecology and water Resources Management Using Data And Models To Benefit Society (2008)

European nitrate directive (CEE/91/676) imposes wide monitoring of Nitrogen in farmlands. The Walloon Region (South of Belgium – 750 000 ha of arable land) develops an original combination of methods to ... [more ▼]

European nitrate directive (CEE/91/676) imposes wide monitoring of Nitrogen in farmlands. The Walloon Region (South of Belgium – 750 000 ha of arable land) develops an original combination of methods to reach European objectives in this topic. On the one hand, water and nitrogen flows and balances are modelled, on the other hand, an Agricultural Surface Survey is put into practice to monitor nitrate nitrogen in the soil at the beginning of the leaching period. The Agricultural Surface Survey is constituted by a 30 reference farms network within more than 200 plots are monitored each in order to fix annual standards for nitrate profiles. Each year, about 1% of the Walloon farms are assessed about their good nitrogen management. Thanks to the existence of a useful database of nitrate profiles measured through six years in the whole Walloon Region, validation of the simulations in the vadose zone can be realised. The comparison of the measured data and the simulation shows a good accuracy of the EPICgrid model. [less ▲]

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