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Berlin Brandenburg

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  • 1
    Language: French
    In: BASE, 01 January 2011, Vol.15(1), pp.143-151
    Description: Cette synthèse bibliographique rappelle les différents schémas de modélisation hydrologique et plus particulièrement la manière dont sont pris en compte les mouvements horizontaux de l'eau dans les sols. Elle met en évidence les hypothèses actuelles et propose une réflexion pour améliorer leur représentation à base physique. Dans le contexte de l'évolution des techniques agricoles, particulièrement de la diminution du recours au labour, il apparait nécessaire d'introduire une description plus fondée de paramètres tels que la conductivité hydraulique horizontale et sa dépendance à la teneur en eau afin de représenter les flux hydrologiques à l'échelle d'une parcelle et à l'échelle d'un bassin versant. Dans ce contexte, une approche par mesure in situ et modélisation physiquement basée est suggérée.
    Description: Modelling of interflows in soils: a review. This review sums up the different schemes in hydrological modelling. Moreover, it underlines how the interflows are taken into account and draws the first lines to improve their physically based representation. In the mood of the change in agricultural practices, especially concerning the conventional tillage reduction in support of conservational tillage, it seems to be necessary to propose a better description of decisive parameters like horizontal hydraulic conductivity. More precisely, the dependence of this parameter with the water retention curve has to be described in order to represent fluxes at the plot scale and at the watershed scale. Under these circumstances, an approach with in situ measurements and physically based modelling is suggested.
    Keywords: Écoulements Hypodermiques ; Écoulement de Subsurface ; Modèle Hydrologique ; Conductivité Hydraulique Horizontale ; Coefficient de Darcy ; Interflow ; Subsurface Flow ; Hydrological Model ; Horizontal Hydraulic Conductivity ; Darcy Coefficient
    ISSN: 1370-6233
    E-ISSN: 1780-4507
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  • 2
    Language: French
    In: Biotechnologie, Agronomie, Société et Environnement [= BASE], 15(1), 143-151. Gembloux, Belgique: Presses Agronomiques de Gembloux (2011).
    Description: This bibliographical review sums up the different schemes in hydrological modelling. Moreover, it underlines how the interflows are taken into account and draws the first lines to improve their physically based representation. In the mood of the change in agricultural practices, especially concerning the conventional tillage reduction in support of conservational tillage, it seems to be necessary to propose a better description of decisive parameters like horizontal hydraulic conductivity. More precisely, the dependence of this parameter with the water retention curve has to be described in order to represent fluxes at the plot scale and at the watershed scale. Under these circumstances, an approach with in situ measurements and physically based modelling is suggested.
    Description: Cette synthèse bibliographique rappelle les différents schémas de modélisation hydrologique et plus particulièrement la manière dont sont pris en compte les mouvements horizontaux de l’eau dans les sols. Elle met en évidence les hypothèses actuelles et propose une réflexion pour améliorer leur représentation à base physique. Dans le contexte de l’évolution des techniques agricoles, particulièrement de la diminution du recours au labour, il apparait nécessaire d’introduire une description plus fondée de paramètres tels que la conductivité hydraulique horizontale et sa dépendance à la teneur en eau afin de représenter les flux hydrologiques à l’échelle d’une parcelle et à l’échelle d’un bassin versant. Dans ce contexte, une approche par mesure in situ et modélisation physiquement basée est suggérée.
    Description: Peer reviewed
    Keywords: Interflow ; Hydrological Model ; Horizontal Hydraulic Conductivity ; Ecoulements Hypodermiques ; Modèle Hydrologique ; Conductivité Hydraulique Horizontale ; Life Sciences :: Environmental Sciences & Ecology ; Sciences Du Vivant :: Sciences De L'Environnement & Écologie ; Life Sciences :: Agriculture & Agronomy ; Sciences Du Vivant :: Agriculture & Agronomie
    Source: ORBi (Open Repository and Bibliography), University of Liège
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  • 3
    Language: English
    In: Vadose Zone Journal, 01 March 2018, Vol.17(1)
    Keywords: Agriculture
    ISSN: 1539-1663
    E-ISSN: 1539-1663
    Source: Directory of Open Access Journals (DOAJ)
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  • 4
    Language: English
    In: Frontiers in Environmental Science, 01 April 2018, Vol.6
    Description: For decades, the development of new visualization techniques has brought incredible insights into our understanding of how soil structure affects soil function. X-ray microtomography is a technique often used by soil scientists but challenges remain with the implementation of the procedure, including how well the samples represent the uniqueness of the pore network and structure and the systemic compromise between sample size and resolution. We, therefore, chose to study soil samples from two perspectives: a macroscopic scale with hydrodynamic characterization and a microscopic scale with structural characterization through the use of X-ray microtomography (X-ray μCT) at a voxel size of 21.53 μm3 (resampled at 433 μm3). The objective of this paper is to unravel the relationships between macroscopic soil properties and microscopic soil structure. The 24 samples came from an agricultural field (Cutanic Luvisol) and the macroscopic hydrodynamic properties were determined using laboratory measurements of the saturated hydraulic conductivity (Ks), air permeability (ka), and retention curves (SWRC). The X-ray μCT images were segmented using a global method and multiple microscopic measurements were calculated. We used Bayesian statistics to report the credible correlation coefficients and linear regressions models between macro- and microscopic measurements. Due to the small voxel size, we observed unprecedented relationships, such as positive correlations between log(Ks) and a μCT global connectivity indicator, the fractal dimension of the μCT images or the μCT degree of anisotropy. The air permeability measured at a water matric potential of −70 kPa was correlated to the average coordination number and the X-ray μCT porosity, but was best explained by the average pore volume of the smallest pores. Continuous SWRC were better predicted near saturation when the pore-size distributions calculated on the X-ray μCT images were used as model input. We also showed a link between pores of different sizes. Identifying the key geometrical indicators that induce soil hydrodynamic behavior is of major interest for the generation of phenomenological pore network models. These models are useful to test physical equations of fluid transport that ultimately depend on a multitude of processes, and induce numerous biological processes.
    Keywords: Soil ; X-Ray Micro-Computed Tomography ; Saturated Hydraulic Conductivity ; Soil Water Retention Curve ; Air Permeability ; Bayesian Statistics ; Environmental Sciences
    E-ISSN: 2296-665X
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  • 5
    Language: English
    In: Geoderma, 15 September 2017, Vol.302, pp.66-75
    Description: The soil water retention curve (SWRC) is a unique relationship between water content and soil water potential. SWRC in near saturation gives the dimension of soil macroporosity which plays an important role in water translocation into soil. Thus, the accurate measurement of SWRC is crucial. The aim of this study is to compare SWRC obtained through two different methods: X-ray computed microtomography (X-ray CT) and evaporation method by HYPROP device. Three different depths (0–10, 25–30 and 45–60cm) are considered for soil sampling. The results showed significant differences in SWRC between the techniques. The SWRC from X-ray CT showed more volumetric water content at 25–30cm (0.044) and 45–60cm (0.024) than evaporation at saturation (0kPa) in cases where the macroporosity was higher. Macropores may have connections with neighbouring pores of smaller sizes. Hence we assume that these pores can be observed through X-ray CT but cannot be evaluated by evaporation. As macropores with narrow opening do not evaporate at very low tension. These pores therefore got empty at relatively higher tension. Consequently, SWRC near saturation appeared rather flatter with the evaporation method where the X-ray CT presented deviation. Accordingly, interpretation of macro pores from SWRC through evaporation method would give comparatively smaller volume of macropores than they really are. Pore morphology and other hydraulic functions of soil, for example, mean connection surface of pores, hydraulic conductivity, and the efficiency of water conducting macropores also support the X-ray CT findings. •Near saturation retention functions differ when using different techniques.•Microtomography shows macropores that don't appear using evaporation method.•In the evaporation method retention curve close to saturation is affected by macropore connections diameter.
    Keywords: Hydrogeology – Electric Properties ; Hydrogeology – Analysis ; Hydrogeology – Methods ; Soil Moisture – Electric Properties ; Soil Moisture – Analysis ; Soil Moisture – Methods ; Cat Scans – Electric Properties ; Cat Scans – Analysis ; Cat Scans – Methods;
    ISSN: 0016-7061
    E-ISSN: 18726259
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  • 6
    Language: English
    In: SOIL, 2016, Vol.2(3), pp.421-431
    Description: Determining soil hydraulic properties is of major concern in various fields of study. Although stony soils are widespread across the globe, most studies deal with gravel-free soils, so that the literature describing the impact of stones on the hydraulic conductivity of a soil is still rather scarce. Most frequently, models characterizing the saturated hydraulic conductivity of stony soils assume that the only effect of rock fragments is to reduce the volume available for water flow, and therefore they predict a decrease in hydraulic conductivity with an increasing stoniness. The objective of this study is to assess the effect of rock fragments on the saturated and unsaturated hydraulic conductivity. This was done by means of laboratory experiments and numerical simulations involving different amounts and types of coarse fragments. We compared our results with values predicted by the aforementioned predictive models. Our study suggests that it might be ill-founded to consider that stones only reduce the volume available for water flow. We pointed out several factors of the saturated hydraulic conductivity of stony soils that are not considered by these models. On the one hand, the shape and the size of inclusions may substantially affect the hydraulic conductivity. On the other hand, laboratory experiments show that an increasing stone content can counteract and even overcome the effect of a reduced volume in some cases: we observed an increase in saturated hydraulic conductivity with volume of inclusions. These differences are mainly important near to saturation. However, comparison of results from predictive models and our experiments in unsaturated conditions shows that models and data agree on a decrease in hydraulic conductivity with stone content, even though the experimental conditions did not allow testing for stone contents higher than 20 %.
    Keywords: Agriculture;
    ISSN: SOIL
    ISSN: 21993971
    E-ISSN: 2199-398X
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  • 7
    Language: French
    In: BASE, 01 January 2011, Vol.15(spécial 2), pp.699-707
    Description: 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. 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 zone vadose ainsi que les déplacements et les transformations des solutés. 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 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. On démontre ainsi 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.
    Description: Hydrology: a partner of geomorphopedology in the scope of a scale-through environmental management. Unsaturated soil and subsoil are often called “critical zone” considering their major interfacing role in our environment. Dealing with solute transfer or water and soil conservation, hydrologic research relies on pedologic descriptions. It is the case from micro to macro scale analysis. Hydrodynamic parameters are derived from pedologic information on soil. They allow hydrologists to quantify and spatially describe the dynamic exchanges between water, soil, crops and atmosphere. The modelling of water and solute transfer through soil and vadose zone also needs them. The paper presents some research highlights on soil behaviour, hydrological modelling and forecasting under climate change. Erosion is another major topic. Soil is a poorly renewable resource. Soil conservation and soft hydraulic management in watersheds deserve more attention. They can help limiting nutrient and sediment transfer to surface water. Again, pedologic information is the starting point of conceptualization and modelling. Furthermore, the Soil Map of Belgium includes information on geomorphology and landscape descriptions which date from decades. They are of first importance to calibrate and validate detachment, transport and sedimentation models. In the current context of high environmental concern, it is demonstrated how hydrology and pedology have to be partners in order to deal with such major issues.
    Keywords: Belgique ; Belgium ; Erosion ; Simulation Models ; Nitrate ; Nitrate ; Hydrologie ; Géomorphologie ; Pédologie ; Relations Eau-Sol-Plante ; Érosion ; Modèle de Simulation ; Hydrology ; Geomorphology ; Soil Sciences ; Water-Soil-Plant Relationships
    ISSN: 1370-6233
    E-ISSN: 1780-4507
    Source: University of Liège Library (ULiège Library)
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  • 8
    Language: English
    In: Coupling X-ray microtomography and macroscopic soil measurements: a method to enhance near saturation functions? Hydrology and Earth System Sciences, 18, 1805-1817.Katlenburg-Lindau, GermanyEuropean Geosciences Union. (2014).
    Description: 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.
    Description: Peer reviewed
    Keywords: X-Ray Microtomography ; Hydrodynamic Behaviour ; Tillage Intensity ; Life Sciences :: Environmental Sciences & Ecology ; Sciences Du Vivant :: Sciences De L'Environnement & Écologie
    Source: ORBi (Open Repository and Bibliography), University of Liège
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  • 9
    Language: English
    In: 2011
    Keywords: Agriculture ; Environmental Sciences ; Ecology ; Agronomy
    ISSN: 1029-7006
    Source: AGRIS (Food and Agriculture Organization of the United Nations)
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  • 10
    Language: English
    In: Characterization of stony soils' hydraulic conductivity using laboratory and numerical experiments. Soil, 2, 421-431.Copernicus GmbH. (2016).
    Description: Determining soil hydraulic properties is of major concern in various fields of study. Although stony soils are widespread across the globe, most studies deal with gravel-free soils, so that the literature describing the impact of stones on the hydraulic conductivity of a soil is still rather scarce. Most frequently, models characterizing the saturated hydraulic conductivity of stony soils assume that the only effect of rock fragments is to reduce the volume available for water flow, and therefore they predict a decrease in hydraulic conductivity with an increasing stoniness. The objective of this study is to assess the effect of rock fragments on the saturated and unsaturated hydraulic conductivity. This was done by means of laboratory experiments and numerical simulations involving different amounts and types of coarse fragments. We compared our results with values predicted by the aforementioned predictive models. Our study suggests that it might be ill-founded to consider that stones only reduce the volume available for water flow. We pointed out several factors of the saturated hydraulic conductivity of stony soils that are not considered by these models. On the one hand, the shape and the size of inclusions may substantially affect the hydraulic conductivity. On the other hand, laboratory experiments show that an increasing stone content can counteract and even overcome the effect of a reduced volume in some cases: we observed an increase in saturated hydraulic conductivity with volume of inclusions. These differences are mainly important near to saturation. However, comparison of results from predictive models and our experiments in unsaturated conditions shows that models and data agree on a decrease in hydraulic conductivity with stone content, even though the experimental conditions did not allow testing for stone contents higher than 20 %.
    Description: Peer reviewed
    Keywords: Stony Soil ; Hydraulic Conductivity ; Life Sciences :: Environmental Sciences & Ecology ; Sciences Du Vivant :: Sciences De L'Environnement & Écologie
    Source: ORBi (Open Repository and Bibliography), University of Liège
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