References of "Degre, Aurore"
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See detailA method for low-flow estimation at ungauged sites: a case study in Wallonia (Belgium)
Grandry, Maud ULg; Gailliez, Sébastien ULg; Sohier, Catherine ULg et al

in Hydrology & Earth System Sciences (2013), 2013(17), 1319-1330

Well-integrated water management can notably require estimating low flows at any point of a river. Depending on the management practice, it can be needed for various return periods. This is seldom ... [more ▼]

Well-integrated water management can notably require estimating low flows at any point of a river. Depending on the management practice, it can be needed for various return periods. This is seldom addressed in the literature. This paper shows the development of a full analysis chain including quality analysis of gauging stations, low-flow frequency analysis, and building of a global model to assess low-flow indices on the basis of catchment physical parameters. The most common distributions that fit low-flow data in Wallonia were two-parameter lognormal and gamma. The recession coefficient and percolation were the most explanatory variables, regardless of the return period. The determination coefficients of the models ranged from 0.51 to 0.67 for calibration and from 0.61 to 0.80 for validation. The regression coefficients were found to be linked to the return period. This was used to design a complete equation that gives the low-flow index based on physical parameters and the desired return period (in a 5 to 50 yr range). The interest of regionalisation and the development of regional models are also discussed. Four homogeneous regions are identified, but to date the global model remains more robust due to the limited number of 20-yr-long gauging stations. This should be reconsidered in the future when enough data will be available. [less ▲]

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See detailModelling agricultural strategies to protect groundwater resources in the Hesbaye aquifer (Belgium)
Sohier, Catherine ULg; Degré, Aurore ULg

in Fraters, Dico; Kovar, Karel (Eds.) International Interdisciplinary Conference on Land Use and Water Quality, Reducing Effects of Agriculture, The Hague, the Netherlands, 10-13 June 2013 (2013)

Groundwater quality is spoiled by various substances resulting from human activities. In addition to pesticides, one of the most problematic substances is nitrate. Pumping prevention areas are strategic ... [more ▼]

Groundwater quality is spoiled by various substances resulting from human activities. In addition to pesticides, one of the most problematic substances is nitrate. Pumping prevention areas are strategic zones in terms of struggle against diffuse pollution by nitrate. In order to reduce diffuse pollution of waters by nitrate, different strategies of agricultural practices can be implemented. Their impact can be evaluated either by monitoring water quality or using an agro-hydrological model. The advantage of modelling is to be able to test long term impacts of implemented measures and impacts of complementary measures. Using EPICgrid distributed agro-hydrological model, we reproduced the current agricultural practices. We calculated nitrate leaching but also the nitrate stock in the root zone. These results were validated through a comparison with a lot of nitrogen stock measurements. (These measurements are compulsory in the Walloon context.) The nitrate concentration in pumping wells was also used to assess the efficiency of the model. After this calibration phase, we modelled several scenarios of more water-protective agricultural practices. Indeed, the Hesbaye galleries represent an important source of drinking water in the Walloon region, it is therefore highly probable that further mitigation measures are going to be imposed in the pumping prevention area. An increase in the area cultivated with cereals, a strong limitation of mineral fertilisation as well as a conversion to grasslands were tested and combined. The results of these simulations show how some agricultural practices scenarios can lead to an important decrease in diffuse pollution by nitrate. Prospective simulations taking into account possible future climate evolution (global change scenarios) are carried out to assess nitrate concentrations near the groundwater table for the deadlines of the WFD (2015, 2021 and 2027). Due to the transfer time through the vadose zone (more than 20 years in some subregions), it is showed that an increase in groundwater nitrate concentrations will occur, in some areas, until at least 2030 before new agricultural practices can impact positively the groundwater quality. [less ▲]

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See detailDifferent methods for spatial interpolation of rainfall data for operational hydrology and hydrological modeling at watershed scale: a review
Ly, Sarann ULg; Charles, Catherine ULg; Degré, Aurore ULg

in Biotechnologie, Agronomie, Société et Environnement = Biotechnology, Agronomy, Society and Environment [=BASE] (2013), 17(2), 392-406

Watershed management and hydrological modeling require data related to the very important matter of precipitation, often measured using raingages or weather stations. Hydrological models often require a ... [more ▼]

Watershed management and hydrological modeling require data related to the very important matter of precipitation, often measured using raingages or weather stations. Hydrological models often require a preliminary spatial interpolation as part of the modeling process. The success of spatial interpolation varies according to the type of model chosen, its mode of geographical management and the resolution used. The quality of a result is determined by the quality of the continuous spatial rainfall which ensues from the interpolation method used. The objective of this article is to review the existing methods for interpolation of rainfall data that are usually required in hydrological modeling. We review the basis for the application of certain common methods and geostatistical approaches used in interpolation of rainfall. Previous studies have highlighted the need for new research to investigate ways of improving the quality of rainfall data and ultimately, the quality of hydrological modeling. [less ▲]

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See detailEstimation of the fascine efficiency in terms of runoff infiltration and sediments deposition
Degré, Aurore ULg; Pineux, Nathalie ULg; Cantreul, Vincent ULg et al

in Geophysical Research Abstracts (2013), 15

Runoff inundations and mudflows are more and more frequent phenomena. In 2011, Belgium had a lot of its municipalities affected by this problematic. Since then, mitigation measures are more and more set ... [more ▼]

Runoff inundations and mudflows are more and more frequent phenomena. In 2011, Belgium had a lot of its municipalities affected by this problematic. Since then, mitigation measures are more and more set up in agricultural watersheds. The fascines are one of these measures which allow to protect the public and private infrastructures and in the same way, which don’t reduce the famers productivity. They consist in branches faggots piled up between two rows of stakes. These linear constructions are mainly put in place across concentrated runoff axis in order to slow down the water and to filter the mud. Only few quantifications of their effectiveness (in terms of flow and concentration water reduction) exist and are however needed to better recommend these types of mitigation measures. Our experiment aims at measuring discharge and mud concentration reduction due to the fascines in a completely defined context. The tests were realised through fascines planted in field border. A watertight surface of 2,45m to 0,80m carries the water to the fascines. Three types of fascines were tested (willow wood fascine, straw fascine, straw compacted fascine), three different water flows were applied (0,5L/s, 3L/s and 6L/s) and three water concentration in dry soil (13g/L, 26g/L, 38g/L) were used. The different factor combinations were tested. The results show that we can expect a reduction of 60% of the flow for the biggest water flows (proportional efficiency with the water flow). The factor interaction study doesn’t allow to see a difference between the type. About the sediment water concentration, the filtration can reach 50%, the fascine with wood faggots showing a better efficiency. Finally, the difference between the fascine type show that straw fascine can support a biggest watershed (25 hectares) than the wood faggot fascine can (5-10 hectares) but during a smaller return period (one year against five years). [less ▲]

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See detailSpatial distribution of erosion and deposition on an agricultural watershed
Pineux, Nathalie ULg; Colinet, Gilles ULg; Degré, Aurore ULg

in Geophysical Research Abstracts (2013), 15

To better understand the agricultural landscapes evolution becomes an essential preoccupation and, for this, it is needed to take into account the sediments deposition, in a distributed way. As it is not ... [more ▼]

To better understand the agricultural landscapes evolution becomes an essential preoccupation and, for this, it is needed to take into account the sediments deposition, in a distributed way. As it is not possible in practice to study all terrestrial surfaces in detail by instrumenting sectors to obtain data, models of prediction are valuable tools to control the current problems, to predict the future tendencies and to provide a scientific base to the political decisions. In our case, a landscape evolution model is needed, which aims at representing both erosion and sedimentation and dynamically adjusts the landscape to erosion and deposition by modifying the initial digital elevation model. The Landsoil model (Landscape design for Soil conservation under soil use and climate change), among others, could fulfil this objective. It has the advantage to take the soil variability into account. This model, designed for the analysis of agricultural landscape, is suitable for simulations from parcel to catchment scale, is spatially distributed and event-based. Observed quantitative data are essential (notably to calibrate the model) but still limited. Particularly, we lack observations spatially distributed on the watershed. For this purpose, we choose a watershed in Belgium (Wallonia) which is a 124 ha agricultural zone in the loamy region. Its slopes range from 0% to 9%. To test the predictions of the model, comparisons will be done with: - sediment measurements which are done with water samplings in four points on the site to compare the net erosion results; - sediment selective measurements (depth variation observed along graduated bares placed on site) to compare the erosion and deposition results; - very accurate DSM’s (6,76 cm pixel resolution X-Y) obtained by the drone (Gatewing X100) each winter. Besides planning what the landscape evolution should be, a revision of the soil map (drew in 1958) is organized to compare with the past situation and establish how the landscape moved in 50 years. The first results of the sediment measurements and of the pictures of the drone will be showed in the presentation. [less ▲]

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See detailHow adaptation strategies of crops could counteract climate change effects? The case of four catchments in Wallonia, Belgium.
Bauwens, Alexandra ULg; Sohier, Catherine ULg; Degré, Aurore ULg

in Geophysical Research Abstracts (2013), 15

A sharp increase in extreme heat and drought stress is projected in Belgium by the end of the 21st century, with the potential to significantly reduce crops’ yields under current agricultural practices ... [more ▼]

A sharp increase in extreme heat and drought stress is projected in Belgium by the end of the 21st century, with the potential to significantly reduce crops’ yields under current agricultural practices. This contribution uses an agro-hydrological model in order to assess the potential effects of climate evolution on crop development, yield, and water balance for the main agricultural productions in the Meuse catchment. Erosion risk is also evaluated. We show that grasslands and maize yield decrease and yield variability increases under climate change scenarios. The leaf area index study permits to put in emphasis the earlier start of the vegetation due to warmer climate. It appears that all the sensitive stages occur earlier in the season and that crops are negatively affected by summer drought stress. The better understanding of crops development under evolving climate allows us to propose some changes in agricultural practices and to assess their effectiveness. We evaluate different strategies of adaptation in agricultural practices in order to reduce the potential negative effects of climate change on grasslands and maize production. Adaptation strategies proposed are advanced sowing and harvesting date, introduction of a cover crop for maize and advance in the cutting dates for grasslands. In the particular case of the Vesdre catchment, shifting the growth period of maize permits to avoid the water-deficit period and allow increased yield. This shift makes it possible to introduce a cover crop that will drastically reduce winter soil erosion. For grassland, the adjustment of the cutting dates favored the first cut and the earlier start of the vegetation. The second cut is less profitable due to summer drought stress. The vulnerability assessments focused on the main rotation encountered in the cultivated areas and in the difference in the cover type of these crops. [less ▲]

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See detailImpacts du changement climatique sur l’hydrologie et la gestion des ressources en eau du bassin de la Meuse : une synthèse
Bauwens, Alexandra ULg; Sohier, Catherine ULg; Degré, Aurore ULg

in Biotechnologie, Agronomie, Société et Environnement = Biotechnology, Agronomy, Society and Environment [=BASE] (2013), 17(1), 76-86

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See detailUsing agro-hydrology to adapt to climate evolutions
Degré, Aurore ULg; Sohier, Catherine ULg; Bauwens, Alexandra ULg et al

in Dewals, Benjamin; Fournier, Maité (Eds.) Transboundary Water Management in a Changing Climate (2013)

Natural phenomena such as floods, drought, erosion, nitrate leaching and plant growth are influenced by climate change. The Soil - Water Systems division of Gembloux Agro-Bio Tech aims at studying these ... [more ▼]

Natural phenomena such as floods, drought, erosion, nitrate leaching and plant growth are influenced by climate change. The Soil - Water Systems division of Gembloux Agro-Bio Tech aims at studying these phenomena; better understanding processes; modelling them in order to predict their change in the future and to assess their potential consequences. Then, we can propose strategies to adapt to these changes. As an agronomy faculty, we believe that adapting agriculture can play a major role in mitigating climate evolution effects at plot and catchment scales. [less ▲]

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See detailHydrological and geopedological dynamics of a forested slope
Deraedt, Deborah ULg; Degré, Aurore ULg; Colinet, Gilles ULg

in Geophysical Research Abstracts (2013), 15

Though forested watersheds are really particular in terms of hydrodynamics, most of the hydrological models oversimplify the phenomena involved. More investigations are unavoidable to improve the ... [more ▼]

Though forested watersheds are really particular in terms of hydrodynamics, most of the hydrological models oversimplify the phenomena involved. More investigations are unavoidable to improve the knowledge and the modelling of this environment. Here is the aim of this study. The studied slope is located on the Houille watershed in the West of the Belgian Ardenne (50 1’47”N, 4 53’22”E) on a silty rocky soil. The site is situated under a Douglas fir (Pseudotsuga menziesii (MIRB.) FRANCO) and spruce stand cover (Picea abies (L.) Karst). It is about 160 meters long with a North-West facing slope between 7 and 55%. The goal of the study is : - to characterise the hydrological and pedogeological dynamics along a forested slope, - to compare these dynamics with the tree growth. For the geopedological part of the study, eight pits were dug to describe the soil and take some soil samples used for granulometric, chemical, etc. analysis. We have used geophysical methods (Electrical Resistivity Tomography and Ground Penetrating Radar) to estimate the soil depth. As for the hydrological part of this study, moisture sensors (capacitive and TDR) have been installed in the pits along the slope. A dye tracing test has been performed to underline the preferential flow and the importance of the subsurface flow. Several trees have been equipped with dendrometers and some measures of the LAI and the height of the trees are planned. [less ▲]

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See detailLow flow regionalisation in the Walloon Region
Grandry, Maud ULg; Verstraete, Arnaud; Gailliez, Sébastien et al

Report (2012)

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See detailMapping overland flow hazard in order to enhance citizens’ awareness of head catchment hydrology
Pineux, Nathalie ULg; Colard, François; Degré, Aurore ULg

Conference (2012, November 15)

Between 1998 and 2004, Europe suffered from more than hundred major inundations, responsible for some 700 deaths, for the moving of about half a million of people and the economic losses of at least 25 ... [more ▼]

Between 1998 and 2004, Europe suffered from more than hundred major inundations, responsible for some 700 deaths, for the moving of about half a million of people and the economic losses of at least 25 billions Euros covered by the insurance policies. Within this context, EU launched the 2007/60/CE directive. This directive aims at a better evaluation of the risks and a better coordination of prevention, protection and crisis management. In most countries, inundation maps only include rivers’ overflowing. In Wallonia (southern part of Belgium), it was decided to include overland flows and mudflows in the flood hazard map. Indeed, the cleaning operations for a village after a storm can lead to an estimated cost of 11 000 €. Average construction cost of retention dams to control off-site damage caused by floods and muddy flows was valued at 380 000€, and yearly dredging costs associated with these retention ponds at 15 000€. A specific study in Gembloux (25 000 inhabitants) estimated the mean annual cost for the runoff damages to 20 000€. This cost only consists of the physical damages caused to the settlements and movable properties of the residents as well as the emergency operations of the firemen and the city. On top of damages to public infrastructure (clogging of trenches, silting up of retention ponds) and to private property, runoff and mud flows generate a significant loss of arable land. Yet, the soil is not an unlimited resource. Moreover, sediments’ transfer to watercourses alters their physical and chemical quality. And that is not to mention the increased psychological stress for people. But head catchment hydrology is not well known. Mapping the overland flood and mud flow hazard over a 17000 km² region is a real challenge. This contribution will present the pragmatic methodology used in Wallonia. In accordance with the Directive, different maps are produced (25, 50 and 100 years of return period and an extreme scenario). Local characteristics are taken into account: rainfall statistics, soil data, land use and relief. They are used to assess runoff production and transfer to an outlet identified as the point where runoff enters the permanent river network. Peak discharge values are used as basis for the mapping. The maps locate the water paths using a colour chart based on the peak discharge. Summer 2011 and spring 2012 storm events as well as a survey made at the municipalities’ level allowed us to validate in some ways the maps produced. Whereas this first approach at regional scale includes uncertainties, the aim of these maps is currently to prompt recognition of the runoff inundation hazard. It is of major importance for soil conservation and citizens’ protection. Above all, it should contribute to lower the damages by early prevention during the design of town-planning projects. [less ▲]

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See detailEvaluation de la recharge des eaux souterraines en Région wallonne : apport de la modélisation EPICgrid et applications
Sohier, Catherine ULg; Grandry, Maud; Gailliez, Sébastien et al

Poster (2012, October 10)

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See detailHydrological instrumentation of a pilot catchment in view to improve the soil loss modeling: focus on the spatial distribution of erosion and deposition (loamy region, Belgium)
Pineux, Nathalie ULg; Degré, Aurore ULg

Poster (2012, July 02)

Nowadays, lots of catchments are affected by inundations or mudflows which are the consequences of excessive runoff and accelerated erosion. That generates also a significant loss of arable land. Yet, the ... [more ▼]

Nowadays, lots of catchments are affected by inundations or mudflows which are the consequences of excessive runoff and accelerated erosion. That generates also a significant loss of arable land. Yet, the soil resource is not an unlimited commodity. Moreover, sediments’ transfer to watercourses alters their physical and chemical quality. The watershed management should aim at both limiting erosion and enhancing deposition in appropriate zones. Therefore, the global objective of this work is to acquire hydropedological data in order to better quantify the erosion and deposition phenomenon in Belgium. The poster presents the field monitoring put in place in our experimental watershed. Indeed, observed quantitative data are essential but still limited. Particularly, we lack observations spatially distributed on the watershed. The watershed is a 124 ha agricultural zone in the loamy region. Its slopes range from 0% to 9%. Instrumentation includes a weather station with disdrometer, discharge measurement at the outlet coupled with water sampling. Fields observations are done to determine the texture redistribution and compared with a previous soil survey realised in 1958. Moreover, regular flights above the area will allow us to obtain a very accurate DEM using Lidar technology (5cm pixel) and observing the relief evolution. The CAESAR model will be tested on this watershed. It aims at representing both erosion and sedimentation and estimates the net erosive flows. This model is based on the Einstein-Brown equations and needs an initial digital elevation model, hourly rainfalls, soil texture, etc. It produces a digital elevation models’ evolution through time. [less ▲]

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See detailTransposability and evaluation of pedotranfer functions for predicting properties of water retention on soils of low chelif. Algeria
Touil, Sami; Saidi, Djamel; Degré, Aurore ULg

Poster (2012, July)

An important question remains about PTF’s transposability to others agropedoclimatic contexts. Models developed and validated in a particular bioclimatic context, were relatively little tested in other ... [more ▼]

An important question remains about PTF’s transposability to others agropedoclimatic contexts. Models developed and validated in a particular bioclimatic context, were relatively little tested in other contexts. The evaluation of PTF to estimate water retention at field capacity pF 2.5 (-330 hPa) and at wilting point pF 4.2 (-15000 hPa) of some soils of Lower Cheliff is presented. [less ▲]

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See detailRégionalisation des débits d'étiage en Région wallonne
Gailliez, Sébastien ULg; Grandry, Maud ULg; Verstraete, Arnaud et al

Conference (2012, April 26)

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See detailSurface water diffuse pollution by PPP: focus on runoff & erosion
Bah, Boubacar Billo ULg; Vandendael, Laurent; Oger, Robert ULg et al

Conference (2012, April 04)

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See detailGISER - Gestion intégrée Sol Erosion Ruissellement - rapport d'activités année 1
Pineux, Nathalie ULg; Maugnard, Alexandre; Demarcin, Pierre ULg et al

Report (2012)

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See detailInfluence de l'état d'ameublissement et de la rugosité du sol des parcelles agricoles sur l'exactitude de l'altitude des points de contrôle positionnés au GPS
Ouedraogo, Mohamar ULg; Debouche, Charles ULg; Degre, Aurore ULg

in Biotechnologie, Agronomie, Société et Environnement = Biotechnology, Agronomy, Society and Environment [=BASE] (2012), 16(1), 33-44

Our goal in this study is to estimate through ranges of variation, the impact of agricultural parcels soil’s tilth and roughness, due to cultivation techniques, on the exactness of ground control points ... [more ▼]

Our goal in this study is to estimate through ranges of variation, the impact of agricultural parcels soil’s tilth and roughness, due to cultivation techniques, on the exactness of ground control points elevation surveyed by RTK (Real Time Kinematic) GPS (Global Positioning System). So, 16 point’s elevations which were located each 100 mm on a transect have been surveyed first by using a total station (TS), and then a RTK GPS in 2 parcels (3 transects per parcel). Cultivation techniques on those parcels were different. The parcel 1 was tilled, and the soil of parcel 2 was prepared for cereal cropping. Then, the analysis of variance has been applied on the differences of TS and RTK GPS elevations data to estimate the confidence interval of ground control points elevation due (i) to soil tilth, whereas the times series statistical method have been applied on elevation data to estimate the confidence interval due (ii) to soil roughness. The confidence intervals of points elevation are estimated being (i) [51 mm; 57 mm], (ii) [-4 mm; 4 mm] for parcel 1, and (i) [97 mm; 113 mm], (ii) [-35 mm; 23 mm], for parcel 2. Results show that ground control point’s elevations exactness is influenced by soil tilth and soil roughness. In conclusion, we can admit that soil tilth and soil roughness have significant impact on the exactness of ground control points located on agricultural parcels. This impact must be considered in DEM errors evaluation of agricultural watershed. [less ▲]

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