References of "Degre, Aurore"
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See detailCoupling X-ray microtomography and macroscopic soil measurements: a method to enhance near saturation functions?
Beckers, Eléonore ULg; Plougonven, Erwan; Gigot, Nicolas et al

E-print/Working paper (in press)

Agricultural management practices influence soil structure, but the characterization of these modifications and consequences are still not completely understood. In this study, we aim at improving water ... [more ▼]

Agricultural management practices influence soil structure, but the characterization of these modifications and consequences are still not completely understood. In this study, we aim at improving water retention and hydraulic conductivity curves using both classical soil techniques and X-ray microtomography in the context of tillage simplification. We show a good match for retention and conductivity functions between macroscopic measurements and microtomographic information. Microtomography highlights the presence of a secondary pore system. Analysis of structural parameters for these pores appears to be significant and offers additional clues for objects differentiation. We show that relatively fast scans supply not only good results, but also enhance near saturation characterization, making microtomography a highly competitive instrument for routine soil characterization. [less ▲]

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See detailÉVOLUTION DE LA TENEUR EN EAU LE LONG D’UNE TOPOSEQUENCE FORESTIERE ARGILO-LIMONEUSE
Deraedt, Deborah ULg; Colinet, Gilles ULg; Degré, Aurore ULg

in Milieux Poreux et Transferts Hydriques (in press)

For the hydrological modeling of forested watersheds, the understanding of the forest hydrodynamic is essential. This study focusses on the hydrology of a Belgian forested plot with high stoniness and ... [more ▼]

For the hydrological modeling of forested watersheds, the understanding of the forest hydrodynamic is essential. This study focusses on the hydrology of a Belgian forested plot with high stoniness and steep slope. The soil water content is monitored at several positions on the toposequence and at different depth. During rain events, peak in soil water content are observed in different depth depending on the position along the toposequence. [less ▲]

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See detailX-ray microtomography: A porosity-based thresholding method to improve soil pore network characterization?
Beckers, Eléonore ULg; Plougonven, Erwan ULg; Roisin, Christian et al

in Geoderma (2014), 219-220

X-ray microtomography, through quantification of soil structure at the microscale, could greatly facilitate the current understanding of soil hydrodynamic behaviour. However, binarisation method and ... [more ▼]

X-ray microtomography, through quantification of soil structure at the microscale, could greatly facilitate the current understanding of soil hydrodynamic behaviour. However, binarisation method and processing choices are subjective and can have a strong impact on results and conclusions. In this study, we test a new method based on the porosity detectable by X-ray microtomography, while validation is achieved through comparison of soil microtomogram information with soil physical measurements. These measurements consist of water retention and unsaturated hydraulic conductivity using two different soil populations with only structural differences. To assess the porosity-based method performances, we compare it to four other methods, namely the global method of Otsu and three recent soil-dedicated local methods. The robustness of the porosity-based method is also tested in regard to different pre-processing procedures. In this paper we demonstrate that soil segmentation through a porosity-based method is an interesting issue. Indeed, it is less demanding in terms of time and computational requirements than its alternatives, and combines robustness and performances broadly comparable with the recent local methods. [less ▲]

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See detailIncrease in Soil Macroporosity managed with Winter Ploughing - a preliminary results
Parvin, Nargish ULg; Chelin, Marie ULg; Hiel, Marie-Pierre ULg et al

Poster (2014, February 07)

Measurement of soil water retention capacity by the conventional pressure plate technique always gives a substantial view of soil porosity distribution. The structural orientation is observed in the ... [more ▼]

Measurement of soil water retention capacity by the conventional pressure plate technique always gives a substantial view of soil porosity distribution. The structural orientation is observed in the beginning (higher water retention at 9.8 to 98 hPa water head pressure indicates greater proportion of macroporosity) of the soil moisture characteristic curve obtained from the water retention measurement. Since, tillage practices generally increase soil porosity, the correlation between soil hydraulics and porosity distribution would expect to be different for different tillage systems. In general, macroporosity increase with the adoption of conservative tillage or no tillage system but the changes can be varied with the seasonal variation. In our study, winter ploughing retains more water at the range of 9.8 to 98 hPa than Strip tillage, No-till residues in and No-till residues out. So, we can conclude that there is certainly increase in macroporosity in ploughing than other conservation practices of reduced tillage and no tillage. [less ▲]

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See detailThe evaluation of unmanned aerial systems-based photogrammetry and terrestrial laser scanning to generate DEMs of agricultural watersheds
Ouedraogo, Mohamar ULg; Degré, Aurore ULg; Debouche, Charles ULg et al

in Geomorphology (2014)

Agricultural watersheds tend to be places of intensive farming activities that permanently modify their microtopography. The surface characteristics of the soil vary depending on the crops that are ... [more ▼]

Agricultural watersheds tend to be places of intensive farming activities that permanently modify their microtopography. The surface characteristics of the soil vary depending on the crops that are cultivated in these areas. Agricultural soil microtopography plays an important role in the quantification of runoff and sediment transport because the presence of crops, crop residues, furrows and ridges may impact the direction of water flow. To better assess such phenomena, 3-D reconstructions of high-resolution agricultural watershed topography is essential. Fine-resolution topographic data collection technologies can be used to discern highly detailed elevation variability in these areas. Knowledge of the strengths and weaknesses of existing technologies used for data collection on agricultural watersheds may be helpful in choosing an appropriate technology. This study assesses the suitability of terrestrial laser scanning (TLS) and unmanned aerial system (UAS) photogrammetry for collecting the fine-resolution topographic data required to generate accurate, high-resolution digital elevation models (DEMs) in a small watershed area (12 ha). Because of farming activity, 14 TLS scans (≈ 25 points m− 2) were collected without using high-definition surveying (HDS) targets, which are generally used to mesh adjacent scans. To evaluate the accuracy of the DEMs created from the TLS scan data, 1,098 ground control points (GCPs) were surveyed using a real time kinematic global positioning system (RTK-GPS). Linear regressions were then applied to each DEM to remove vertical errors from the TLS point elevations, errors caused by the non-perpendicularity of the scanner’s vertical axis to the local horizontal plane, and errors correlated with the distance to the scanner’s position. The scans were then meshed to generate a DEMTLS with a 1 × 1 m spatial resolution. The Agisoft PhotoScan and MicMac software packages were used to process the aerial photographs and generate a DEMPSC (Agisoft PhotoScan) and DEMMCM (MicMac), respectively, with spatial resolutions of 1 × 1 m. Comparing the DEMs with the 1,098 GCPs showed that the DEMTLS was the most accurate data product, with a root mean square error (RMSE) of 4.5 cm, followed by the DEMMCM and the DEMPSC, which had RMSE values of 9.0 and 13.9 cm, respectively. The DEMPSC had absolute errors along the border of the study area that ranged from 15.0 to 52.0 cm, indicating the presence of systematic errors. Although the derived DEMMCM was accurate, an error analysis along a transect showed that the errors in the DEMMCM data tended to increase in areas of lower elevation. Compared with TLS, UAS is a promising tool for data collection because of its flexibility and low operational cost. However, improvements are needed in the photogrammetric processing of the aerial photographs to remove non-linear distortions. [less ▲]

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See detailReprésentation du couvert forestier dans la modélisation hydrologique : Comparaison de dix modèles
Deraedt, Deborah ULg; Colinet, Gilles ULg; Claessens, Hugues ULg et al

in Biotechnologie, Agronomie, Société et Environnement = Biotechnology, Agronomy, Society and Environment [=BASE] (2014), 18(1), 83-96

There are many hydrological models, some of which can be used for forested environments. This review aims to compare ten of them (BILJOU, EPIC, BROOK90, SWAT, RHESSys, MIKE SHE, SHETRAN, WaSiM ETH, DHSVM ... [more ▼]

There are many hydrological models, some of which can be used for forested environments. This review aims to compare ten of them (BILJOU, EPIC, BROOK90, SWAT, RHESSys, MIKE SHE, SHETRAN, WaSiM ETH, DHSVM et Hydrus) to guide the choice. The compared fluxes are the interception, the transpiration and the root water uptake, the root distribution, the undercover effect, the tree growth and the model validation. The review underlines that each model deals with the forest fluxes in different ways. Most of the time, interception is similarly dealt by the models and the root distribution is used in the process of root water uptake. Understory and growth are seldom considered. [less ▲]

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See detailUncertainty assessment of ephemeral gully identification, characteristics and topographic threshold when using aerial photographs in agricultural settings
Maugnard, Alexandre; Cordonnier, Hélène; Degré, Aurore ULg et al

in EARTH SURFACE PROCESSES AND LANDFORMS (2014)

Manual digitizing on aerial photographs is still commonly used for characterizing gully erosion over large areas. Even when automated detection procedures are implemented, manual digitizing is frequently ... [more ▼]

Manual digitizing on aerial photographs is still commonly used for characterizing gully erosion over large areas. Even when automated detection procedures are implemented, manual digitizing is frequently being resorted to in order to constitute reference datasets used for training and validation. In both cases, manual digitizing entails some subjective decisions on behalf of the operator, which introduces uncertainty into the resulting datasets. To assess the magnitude of this uncertainty, 11 experienced operators were asked to digitize and classify ephemeral gullies (EGs) on cropland following a standardized methodology. The resulting 11 datasets were compared in terms of number, type and location of EGs. Furthermore, for EGs located on a welldefined runoff flow concentration axis, the slope versus contributing area topographic thresholds required for initiating gully channels were assessed using four thresholding methods, and compared across the 11 datasets. The operators identified 259 different EGs. However, the number (52–139) and sum total length (8.9–23.7 km) of EGs varied widely across operators. Only 34% of the EGs were digitized by more than half of the operators, and 7% were identified by all. Identification of EGs located on a well-defined flow concentration axis proved least subjective. The longer the EG and the more fields the EG crossed, the larger the number of operators that were able to identify it. EGs were also most easily identified when located in sugar beet fields as compared to other crops. EG classification and topographic threshold lines were also found to be strongly operator-dependent. Quantile regression appeared to be one of the most robust thresholding methods. Operator subjectivity when digitizing EGs on orthophotographs introduces uncertainty that should be taken into account in future remote sensing-based studies of EG erosion whenever they rely, in part or in full, on manual photograph interpretation. [less ▲]

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See detailConcepts d’efficience et de productivité de l’eau (synthèse bibliographique)
Kambou, Donkora ULg; Xanthoulis, Dimitri ULg; Ouattara, Korodjouma et al

in Biotechnologie, Agronomie, Société et Environnement = Biotechnology, Agronomy, Society and Environment [=BASE] (2014), 18(1),

Water efficiency and productivity indicators are used in many scientific disciplines, usually to account for water losses that occur during its use, or products generated per unit of water consumed. The ... [more ▼]

Water efficiency and productivity indicators are used in many scientific disciplines, usually to account for water losses that occur during its use, or products generated per unit of water consumed. The interpretation of these indicators is very diverse in the literature. However, the majority of definitions consider water efficiency as a measure of the effectiveness of irrigation, and view water productivity as a measure of the effectiveness of the physiological processes of both biomass production and crop yield formation, linked to the actual consumption of water by the crops. Thus, the consensus seems to be for water application efficiency (Ea) to be considered as the ratio of actual evapotranspiration to the water applied and productivity as the ratio of yield to actual evapotranspiration. The point of divergence relates fundamentally to the understanding of the constituent expressions of productivity (PE, product/“water consumed”) and efficiency of water application (Ea, “water consumed”/“applied water”). Indeed, the term “water consumed” is referred to variously by several authors as “actual evapotranspiration”, “gross irrigation plus rainfall”, “evapotranspiration plus water lost at the plot but beneficial to other users”, etc. Furthermore, while providing more details on the concepts of efficiency and water productivity, this review shows that the factors affecting these indicators have not yet been sufficiently elucidated. Thus, one of the axes of investigation could be to model the application efficiency of water firstly, according to water management practices and secondly, in terms of productivity levels in relation to the crop establishment period. [less ▲]

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See detailAssessing the influence of crop management strategies on the distribution of soil water content by ERT
Chelin, Marie ULg; Parvin, Nargish ULg; Hiel, Marie-Pierre ULg et al

Poster (2013, December 20)

Amongst other functions, cover crops are known to increase the stability of the soil structure. Commonly, their suppression is realized by using conventional tillage, but that it has been demonstrated to ... [more ▼]

Amongst other functions, cover crops are known to increase the stability of the soil structure. Commonly, their suppression is realized by using conventional tillage, but that it has been demonstrated to damage the soil structure, which directly impacts the soil water content. The proposed alternatives vary in terms of date, depth and type of tillage. As the soil water content is a major factor in agriculture, it is essential to better understand the influence of the cover crop management on its spatio-temporal distribution. Recent studies demonstrated the relevancy of the electrical resistivity tomography (ERT) to estimate the three-dimensional soil water content distribution. However, only a few of them were performed under field conditions. This study aims at (i) validating the use of the ERT method to estimate the soil water content distribution under field conditions (ii) quantifying the influence of cover crop management on the dynamic of soil water content along the growing season of a maize crop and on Belgian soil types. Three types of cover crop management content will be daily monitored: strip tillage, spring tillage and winter tillage. In order to assess the impact of plants on the soil water distribution, an additional plot will be burned after winter tillage. ERT will be used on a surface of 2 m² for each cover crop management. The validation of the average soil water content will be attended by using Time Domain Reflectrometers (TDR) and suction cups. The water stock obtained by ERT will be validated by using data from a weather station for the estimation of the evapotranspiration and rainfall and minirhizotrons for the assessment of the root water uptake. [less ▲]

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See detailSoil infrastructure evolution and its effect on water transfer processes under contrasted tillage systems with preliminary results of soil moisture sensor calibration
Parvin, Nargish ULg; Degré, Aurore ULg; Garré, Sarah ULg et al

Poster (2013, December 05)

The heterogeneity of soil structure and porosity are highly influenced by external factors like tillage systems and other land management approaches. The aim of this project is to investigate the effect ... [more ▼]

The heterogeneity of soil structure and porosity are highly influenced by external factors like tillage systems and other land management approaches. The aim of this project is to investigate the effect of soil tillage along with residue management on the changing pattern of soil structure. This investigation will help to emphasize the different water flow dynamics especially the preferential flow processes through the soil that are influenced by the changes in structural distribution in the soil profile. Mostly the preferential flow of water is addressed by the apparent velocity through the soil but this study will focus on soil structure along with soil moisture dynamics at aggregate scale or more specifically at pedon scale. The experimentation has been started from June 2013 in the research field known as Solcouvert (objects: strip-till (ST) versus winter ploughing (WP)) and Solresidus (objects: no-till with organic matter restitution (NI) versus no-till without organic matter restitution (NO)). Soil profile description has been carried out in the four objects of land management. Soil sampling has been done in different depths of soil according to the soil profile description. Soil samples will be used for the measurement of water retention capacity, hydraulic conductivity and x-ray microtomography. In addition, there will be soil moisture sensors (Decagon 10HS, 5TM and ML3 Thetaprobe) in the field under four different trials. The soils from the different trials and also from different depths (0-15, 25-30 and 50-60 cm) were calibrated with the sensors. The calibration results were significantly (p<0.05) different between Solcouvert and Solresidus and there was also significant (p<0.05) difference among depths of same field especially between 0-15 and 50-60 cm. Soil bulk density and textural differences are the main reason for the differences of moisture content of different sites and depths measured by the moisture probes. In addition, the results were inconsistent along with overestimation of moisture content if the manufacturer based equation is used for the calibration. In our study, to capture the total soil moisture networks, the moisture sensors will be in the field in winter to spring and summer to autumn. All the experiments will be repeated twice a year. For the specific spatio-temporal comparison, the monitoring results from electrical resistance tomography will be available from the collaborated project of the same faculty. [less ▲]

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See detailSoil infrastructure evolution and its effect on water transfer processes under contrasted tillage systems
Parvin, Nargish; Degré, Aurore ULg; Garré, Sarah ULg et al

Poster (2013, December 05)

The heterogeneity of soil structure and porosity are highly influenced by external factors like tillage systems and other land management approaches. The aim of this project is to investigate the effect ... [more ▼]

The heterogeneity of soil structure and porosity are highly influenced by external factors like tillage systems and other land management approaches. The aim of this project is to investigate the effect of soil tillage along with residue management on the changing pattern of soil structure. This investigation will help to emphasize the different water flow dynamics especially the preferential flow processes through the soil that are influenced by the changes in structural distribution in the soil profile. Mostly the preferential flow of water is addressed by the apparent velocity through the soil but this study will focus on soil structure along with soil moisture dynamics at aggregate scale or more specifically at pedon scale. The experimentation has been started from June 2013 in the research field known as Solcouvert (objects: strip-till versus winter ploughing) and Solresidus (objects: no-till with organic matter restitution versus no-till without organic matter restitution). Soil profile description has been carried out in the four objects of land management. Soil sampling has been done in different depths of soil according to the soil profile description. Soil samples will be used for the measurement of water retention capacity, hydraulic conductivity and x-ray microtomography. In addition there will be soil moisture sensors (Decagon 10HS, 5TM and ML3 Thetaprobe) in the field under four different trials. The soils from the different trials and also from different depths (0-15, 25-30 and 50-60 cm) were calibrated with the sensors. The calibration results were significantly (p<0.05) different between Solcouvert and Solresidus and there was also significant (p<0.05) difference among depths of same field especially between 0-15 and 50-60 cm. Soil bulk density and textural differences are the main reason for the differences of moisture content of different sites and depths measured by the moisture probes. In addition, the results were inconsistent along with overestimation of moisture content if the manufacturer based equation is used for the calibration. We conclude that, site and depth wise calibration of low cost sensors is very essential for the interpretation of results. In our study, to capture the total soil moisture networks, the moisture sensors will be in the field during the crop season. All the experiments will be repeated twice a year. For the specific spatio-temporal comparison, the monitoring results from electrical resistance tomography will be available from the collaborated project of the same faculty. [less ▲]

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See detailÉlaboration du référentiel de compétences du master bioingénieur en Sciences et Technologies de l'Environnement
Colaux-Castillo-Bocanegra, Catherine ULg; Colinet, Gilles ULg; Debouche, Charles ULg et al

in Poulin, Richard (Ed.) Séminaire CITEF 2013 La liaison formation-emploi : l'approche compétences et la formation tout au long de la vie (2013, October 18)

Le département des Sciences et Technologies de l’Environnement (STE) de Gembloux Agro-Bio Tech faculté de l’Université de Liège a profité d’un changement d’intitulé de son diplôme de bioingénieur pour ... [more ▼]

Le département des Sciences et Technologies de l’Environnement (STE) de Gembloux Agro-Bio Tech faculté de l’Université de Liège a profité d’un changement d’intitulé de son diplôme de bioingénieur pour réviser son programme des études. Pour ce faire, il a adopté l’approche compétence. Afin de préparer au mieux ses futurs diplômés aux attentes du monde professionnel actuel et à venir, des anciens diplômés et des employeurs potentiels ont participé à la validation du référentiel de compétences associé à cette formation. Cette publication reprend les étapes clés de la création du référentiel de compétences et son exploitation dans la conception d’un programme des études cohérent. [less ▲]

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See detailContribution of an Agro-Hydrological Model
Degré, Aurore ULg; Sohier, Catherine ULg

Scientific conference (2013, September 13)

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See detailTemporal variability of nitrous oxide fluxes from a fertilized grassland in Belgium: preliminary results from dynamic closed chambers.
Beekkerk van Ruth, Jöran ULg; Moureaux, Christine ULg; Degré, Aurore ULg et al

Poster (2013, April 09)

Presentation of preliminary results from N2O measurements over a grassland using dynamic closed chambers. See attached folders for more detail.

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See detailTEMPORAL VARIABILITY OF N2O FLUXES FROM A FERTILIZED GRASSLAND: PRELIMINARY RESULTS FROM DYNAMIC CLOSED CHAMBERS
Beekkerk van Ruth, Jöran ULg; Moureaux, Christine ULg; Degré, Aurore ULg et al

Poster (2013, April 09)

This work presents preliminary results of nitrous oxide (N2O) fluxes measured by dynamic closed chambers from a fertilized grassland grazed by the Belgian Blue breed of cattle. It is part of a project ... [more ▼]

This work presents preliminary results of nitrous oxide (N2O) fluxes measured by dynamic closed chambers from a fertilized grassland grazed by the Belgian Blue breed of cattle. It is part of a project funded by the public service of Wallonia (SPW-DGARNE), whose objectives are to make a carbon/CO2 balance of the grassland (Jérôme et al., 2013) and to quantify CH4 (Dumortier et al., 2013) and N2O fluxes. The site is located in Dorinne (Dorinne Terrestrial Observatory), Belgium (50° 18’ 44” N; 4° 58’ 07” E; 248 m al.). It is a permanent grassland of ca. 4.2 ha with a moderate slope of 1 to 2 %. Mineral fertilisation took place in March and May 2012. Two cylindrical chambers of 19,2 cm diameter and 11,5 cm height were placed inside a protected area around a micrometeorological station. An infrared gas analyser (Thermofischer 46i) was used in order to measure the N2O concentrations inside of the chambers, closed by automatically controlled lids and ventilated by a constant air flow of 1liter/min. These devices were completed by adjacent soil humidity and temperature sensors. The first measurement campaign took place during June and July 2012. The chambers were installed in the field and N2O fluxes were followed without manipulation. N2O fluxes were characterised by a background emission (between 2 and 10 ngN.m2s􀀀1) on which intense but time limited peaks (between 50 and 300 ngN.m2s􀀀1) superimposed. Peaks were found to be mainly linked to fertilisation and driven by precipitation. Background fluxes were found to correlate positively with soil temperature. Secondly, a manipulation experiment took place in November 2012: two different fertilizer treatments were applied to the chambers. Doses of respectively 100 and 200 kg N/ha of ammonium nitrate were sprayed in the chambers (equivalent to a 8mmprecipitation). N2O fluxes peaked shortly after fertiliser application (respectively 300 and 550 ngN.m2s􀀀1), as well as after a posterior rain event (respectively 800 and 1500 ngN.m2s􀀀1). The peak dynamics suggests a complex interaction between soil humidity and nitrogen availability, which is under study. Dumortier et al., Geophysical Research Abstracts, Vol. 15, EGU2013-2083-1, 2013 Jérôme et al., Geophysical Research Abstracts Vol. 15, EGU2013-6989, 2013 [less ▲]

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See detailGISER - Gestion intégrée Sol Erosion Ruissellement - rapport d'activités année 2
Pineux, Nathalie ULg; Maugnard, Alexandre; Demarcin, Pierre ULg et al

Report (2013)

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See detailRelevance of pedotopographical indicators in the assessment of spatial distributions of soil depth and soil water resources under forest stands : General Methodology
Ridremont, François ULg; Deraedt, Deborah ULg; Robert, Tanguy et al

Poster (2013, March)

Water resources constitute one of the most decisive factors of the adaptation of forest ecosystems facing climate changes. The assessment of soil water resources should lead a better understanding of ... [more ▼]

Water resources constitute one of the most decisive factors of the adaptation of forest ecosystems facing climate changes. The assessment of soil water resources should lead a better understanding of forest sites vulnerability to water stress and provide appropriate management recommendations for the choice of trees species and sylvicutlural techniques. This study aims to assess the relevance of pedotopographical indicators in the assessment of spatial distributions of soil depth and soil water resources under forest stands. The study area is located in the shale-slate stones pedological context of the Belgian Ardenne ecoregion. It falls within the constrasted relief of the Houille watershed and is 90% covered by forests. The estimation of spatial and profile distributions of water resources will be based on a multi-year monitoring of real time soil moisture content using TDR technology : subsurface (15 cm) on systematic sampling and profile (. 70 cm) on 32 local sites equipped with TDR pvc tubes. Additional laboratory analysis will be conducted to determine soil properties influencing soil water content (texture, organic matter content...). Directly impacting soil water content, soil depth and stoniness will be investigated in contrasting topographic conditions by (i) two traditional and destructive methods : 32 soil pits & 160 holes with auger soil; and (ii) an electromagnetic and non intrusive method : 5120m of Ground Penetrating Radar traces with 200 and 500 MHz antennas. The identification of soil and terrain attributes, able to explain distribution of soil water content and soil depth, will be done by digital cartographic resources exploitation : (i) Digital Elevation Model with different spatial resolutions (Lidar, 1 m2; Erruissol DEM, 100 m2; Aster DEM, 9.103m2) and (ii) Digital Soil Map of Wallonia. It is expected that the results could lead to the development of operational tools to ensure the forest site . tree species adequacy in order to increase resilience of forest ecosystems to ecological drifts. [less ▲]

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See detailCartographie du risque d’érosion hydrique à l’échelle parcellaire en soutien à la politique agricole wallonne (Belgique)
Maugnard, Alexandre; Bielders, Charles; Bock, Laurent ULg et al

in Étude et Gestion des Sols (2013), 20(2), 127-141

L’érosion hydrique des sols pose le problème de la protection de la ressource « sol » mais également de la prévention des impacts environnementaux et sociétaux qui y sont associés tels que la dégradation ... [more ▼]

L’érosion hydrique des sols pose le problème de la protection de la ressource « sol » mais également de la prévention des impacts environnementaux et sociétaux qui y sont associés tels que la dégradation de la qualité des eaux de surface, l’envasement des retenues d’eau et des bassins d’orage ou encore les inondations boueuses. Afin de cibler au mieux les mesures de lutte anti-érosives, il convient d’identifier les parcelles agricoles les plus à risque d’érosion. Mettant à profit la disponibilité d’importantes bases de données en matière de climat, sol, topographie, parcellaire et occupation du sol, une procédure automatisée de calcul de l’aléa érosion hydrique potentielle à l’échelle parcellaire, adaptée du modèle RUSLE, a été mise au point pour la Wallonie (Belgique). La carte de l’aléa érosion potentielle montre une sensibilité maximale à l’érosion hydrique en Ardenne et Haute-ardenne, en raison du relief accentué et d’une érosivité plus importante des pluies. Pour les principales zones agro-pédologiques de Wallonie, un suivi des principales cultures (céréales d’hiver, mais, betterave, pomme de terre, colza, lin) a également été réalisé, permettant d’estimer le facteur cultural C des principales successions culturales et ainsi l’érosion effective. La prise en compte de l’occupation du sol fait cette fois ressortir un aléa maximal dans les régions (sablo-)limoneuses et le Condroz, en raison des superficies importantes de grandes cultures industrielles. En Ardenne et Haute Ardenne, l’aléa d’érosion effective est faible en raison d’une couverture végétale dominée par les prairies permanentes. Enfin, sur base de la carte numériques des sols de Wallonie, une classification de la vulnérabilité des sols à l’érosion a été établie à partir du volume de sol pouvant être exploité par les racines. La vulnérabilité apparaît élevée sur une majorité du territoire wallon, à l’exception des Régions (sablo-)limoneuses et de la Région jurassique. Un indice d’érosion, calculé comme le rapport de l’érosion potentielle (aléa) sur l’érosion tolérable (vulnérabilité) permet de calculer le risque d’érosion hydrique et, par conséquent, de cibler au mieux les parcelles pour lesquelles l’érosion constitue une menace majeure pour leur valorisation durable. Une gestion appropriée de ces parcelles par un choix judicieux en termes d’occupation du sol (forêt, prairie, rotations culturales) et de pratiques culturales (p.ex., TCSL, inter-cultures) devrait permettre d’y réduire les risques de dégradation des sols par érosion hydrique. [less ▲]

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