References of "Hallet, Vincent"
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See detailNitrate dynamic and pathways in fractured limestone aquifers : From soil leaching to groundwater discharge in surface water
Briers, Pierre ULg; Schmit, Flore; Orban, Philippe ULg et al

Conference (2016, July 27)

Fractured – karstified limestone aquifers constitute important, but vulnerable groundwater reservoirs in many areas across the World. Such carbonate systems are highly heterogeneous leading to a high ... [more ▼]

Fractured – karstified limestone aquifers constitute important, but vulnerable groundwater reservoirs in many areas across the World. Such carbonate systems are highly heterogeneous leading to a high spatial and temporal variability of fluxes across the soil – vadose zone – groundwater – surface water continuum. One of the main challenges worldwide is to protect such groundwater bodies from diffuse pollutions, in particular agricultural chemicals such as nitrate. To face such problems and to propose adequate pollution mitigation scenarios, the objective here was to better understand and quantify nitrate dynamics and pathways in the subsurface and at the groundwater – surface water interface. The transfer of nitrate was investigated in different ways such as monitoring of concentrations in both groundwater and surface water, tracer experiments in the unsaturated – saturated continuum and regional investigations on groundwater chemistry including stable isotopes of nitrate and other compounds. Results show that nitrate concentrations are relatively stable both in groundwater and surface water during the low flow period (i.e. from spring to autumn). A temporary but significant increase in nitrate concentration is observed in groundwater and rivers during the winter, related to release of residual nitrate from agricultural soils driven by infiltration water. In period of high precipitations and runoff, dilution is measured in the river. Monitoring and tracer test results also highlight the fact that the migration of dissolved contaminants across the unsaturated zone of limestone rocks is very fast and governed by gravitational flows. In the rivers, macroinvertebrates and benthic diatoms were sampled at several sites to assess ecological status and structural and functional response to alteration of water quality (nutrient enrichment) and quantity (current velocity and stream habitats). Diatom indices and community structure indicated good to very good status in both studied streams, indicating that elevated nitrate concentration have no detectable effect on biological quality of the surface waters. The combination of all these results allows developing a detailed conceptual model of the dynamics of nitrate (and other agricultural contaminants) in fractured / karstified limestone aquifers, with improved estimates of nitrate trends and dynamics in both groundwater and rivers. [less ▲]

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See detailDélivrable D3.3 Bilans hydrogéologiques
Schmit, Flore; Hallet, Vincent; Briers, Pierre ULg et al

Report (2016)

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See detailCharacterization of stream - aquifer interaction in carbonate rocks
Briers, Pierre ULg; Sohier, Catherine ULg; Schmit, Flore et al

Poster (2014, September 30)

Groundwater - surface water interactions play a fundamental role in terms of quantity and quality of water and in terms of ecological quality of rivers. Despite many research efforts and the necessity to ... [more ▼]

Groundwater - surface water interactions play a fundamental role in terms of quantity and quality of water and in terms of ecological quality of rivers. Despite many research efforts and the necessity to better understand such interactions in order to reach effective management of water resources, stream-aquifer exchanges remain poorly understood, in particular in fractured carbonate environments. [less ▲]

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See detailAquifère crayeux de Hesbaye
Orban, Philippe ULg; Brouyère, Serge ULg; Compère, Jean-michel et al

in Dassargues, Alain; Walraevens, Kristine (Eds.) Watervoerende lagen en grondwater in Belgïe - Aquifères et eaux souterraines en Belgique (2014)

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See detailCalcaires et grès du Synclinorium de Dinant
Gesels, Julie ULg; Nogarède, Pierre; Hallet, Vincent et al

in Dassargues, Alain; Walraevens, Kristine (Eds.) Watervoerende lagen en grondwater in Belgïe - Aquifères et eaux souterraines en Belgique (2014)

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See detailDélivrable D2.1 : Mise à jour des données concernant les bassins étudiés
Briers, Pierre ULg; Schmit, Flore; Sohier, Catherine et al

Report (2014)

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See detailCarte hydrogéologique de Wallonie, Waremme-Momalle 41/3-4, Heers-Borgloon 33/7-8, 1/25.000 : [notice explicative]
Hallet, Vincent; Peters, Valérie; Ruthy, Ingrid ULg et al

Book published by Service Public de Wallonie, DGARNE - Actualisation partielle: juin 2012 - Première édition : mars 2000 (2012)

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See detailCarte hydrogéologique de Wallonie, Waremme-Momalle 41/3-4, Heers-Borgloon 33/7-8
Hallet, Vincent; Ruthy, Ingrid ULg; Peters, Valérie et al

Cartographic material (2012)

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See detailValorisation de la Carte des Sols dans un cadre inattendu - Le tourisme à caractère scientifique
Rekk, Samantha; Legrain, Xavier ULg; Bock, Laurent ULg et al

Poster (2010, November 24)

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See detailDetailed study on groundwater pollution by bentazone in the Walloon Region, Belgium
Limbourg, Quentin; Mattern, Samuel; Hallet, Vincent et al

Report (2010)

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See detailUsing Electrical Resistivity Tomography and Self-potential Methods for Wells Implementations in Fractured Limestones
Robert, Tanguy ULg; Dassargues, Alain ULg; Brouyère, Serge ULg et al

in EarthDoc - Near Surface 2009 – 15th European Meeting of Environmental and Engineering Geophysics (2009, September 09)

Electrical resistivity tomography (ERT) and self-potential (SP) investigations were conducted in fractured limestones in Belgium. The aim of this study was to find suitable positions for high yield water ... [more ▼]

Electrical resistivity tomography (ERT) and self-potential (SP) investigations were conducted in fractured limestones in Belgium. The aim of this study was to find suitable positions for high yield water wells. Large ERT profiles (640 meters) allowed us to image the resistivity distribution of the first 60 meters of the subsurface and to detect and characterize (in terms of direction, width and depth) fractured zones expected to be less resistive. Data errors, DOI indexes and sensitivity models were analysed in order to calculate the depth of investigation of ERT and to avoid the misinterpretation of the resulting images. Self-potential measurements were performed along electrical profiles to narrow the possible locations given by the electrical images. Some negative anomalies possibly related to preferential flow were detected. ‘Ground truth’ geological data as well as pumping tests information gave us a way to assess the contribution of geophysics to a drilling programme. Wells implemented in low resistivity zones associated with SP anomalies have very high yields. Inversely, wells drilled in resistive zones or outside SP anomalies have poorer capacities. An apparent coupling coefficient between SP signals and differences in hydraulic heads was also estimated in order to image the water table. [less ▲]

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