References of "Briers, Pierre"
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See detailInnovative contaminant mass flux monitoring in an aquifer subject to tidal effects.
Jamin, Pierre ULiege; Cosme, Frédéric; Briers, Pierre ULiege et al

in Groundwater Monitoring & Remediation (2020), (Winter),

Exposure from groundwater contamination to aquatic receptors residing in receiving surface water is dependent upon the rate of contaminated groundwater discharge. Characterization of groundwater fluxes is ... [more ▼]

Exposure from groundwater contamination to aquatic receptors residing in receiving surface water is dependent upon the rate of contaminated groundwater discharge. Characterization of groundwater fluxes is challenging, especially in coastal environments where tidal fluctuations result in transient groundwater flows towards these receptors. This can also be further complicated by the high spatial heterogeneity of subsurface deposits enhanced by anthropogenic influences such as the mixing of natural sediments and backfill materials, the presence of subsurface built structures such as sheet pile walls or even occurrence of other sources of contaminant discharge. In this study, the Finite Volume Point Dilution Method (FVPDM) was successfully used to characterize highly transient groundwater flows and contaminant mass fluxes within a coastal groundwater flow system influenced by marked tides. FVPDM tests were undertaken continuously for more than 48 hours at 6 groundwater monitoring wells, in order to evaluate groundwater flow dynamics during several tide cycles. Contaminant concentrations were measured simultaneously which allowed calculating contaminant mass fluxes. The study highlighted the importance of the aquifer heterogeneity, with groundwater fluxes ranging from 10-7 to 10-3 m s-1. Groundwater flux monitoring enabled a significant refinement of the conceptual site model, including the fact that inversion of groundwater fluxes was not observed at high tide. Results indicated that contaminant mass fluxes were particularly higher at a specific monitoring well, by more than 3 orders of magnitude, than at other wells of the investigated aquifer. This study provided crucial information for optimizing further field investigations and risk mitigation measures. [less ▲]

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See detailDynamics of greenhouse gases in the river–groundwater interface in a gaining river stretch (Triffoy catchment, Belgium)
Jurado, Anna; Borges, Alberto ULiege; Pujades, Estanislao et al

in Hydrogeology Journal (2018)

This study investigates the occurrence of greenhouse gases (GHGs) and the role of groundwater as an indirect pathway of GHG emissions into surface waters in a gaining stretch of the Triffoy River ... [more ▼]

This study investigates the occurrence of greenhouse gases (GHGs) and the role of groundwater as an indirect pathway of GHG emissions into surface waters in a gaining stretch of the Triffoy River agricultural catchment (Belgium). To this end, nitrous oxide (N2O), methane (CH4) and carbon dioxide (CO2) concentrations, the stable isotopes of nitrate, and major ions were monitored in river and groundwater over 8 months. Results indicated that groundwater was strongly oversaturated in N2O and CO2 with respect to atmospheric equilibrium (50.1 vs. 0.55 μg L−1 for N2O and 14,569 vs. 400 ppm for CO2), but only marginally for CH4 (0.45 vs. 0.056 μg L−1), suggesting that groundwater can be a source of these GHGs to the atmosphere. Nitrification seemed to be the main process for the accumulation of N2O in groundwater. Oxic conditions prevailing in the aquifer were not prone for the accumulation of CH4. In fact, the emissions of CH4 from the river were one to two orders of magnitude higher than the inputs from groundwater, meaning that CH4 emissions from the river were due to CH4 in-situ production in riverbed or riparian zone sediments. For CO2 and N2O, average emissions from groundwater were 1.5 × 105 kg CO2 ha−1 year−1 and 207 kg N2O ha−1 year−1, respectively. Groundwater is probably an important source of N2O and CO2 in gaining streams but when the measures are scaled at catchment scale, these fluxes are probably relatively modest. Nevertheless, their quantification would better constrain nitrogen and carbon budgets in natural systems. [less ▲]

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See detailCarte hydrogéologique de Wallonie, Vielsalm - Houvegnez, 56/1-2
Briers, Pierre ULiege; Gilson, M.; Ruthy, I. et al

Cartographic material (2018)

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See detailStatistical description of hydrogeological parameters for the main aquifer contexts in Wallonia
Briers, Pierre ULiege; Dollé, Fabien ULiege; Orban, Philippe ULiege et al

Conference (2017, January 20)

The Walloon Region Soil decree proposes a series of guidance documents associated to the procedures for site remediation operations. Among others, one of these documents describes methodologies and tools ... [more ▼]

The Walloon Region Soil decree proposes a series of guidance documents associated to the procedures for site remediation operations. Among others, one of these documents describes methodologies and tools for risk assessment of pollutant leaching from soil to groundwater and for pollutant dispersion through groundwater. These tools require using estimates of hydrogeolocial parameters such as hydraulic conductivity, effective (transport) porosity etc. In this context, an inventory of hydrogeological studies (regional characterization studies, groundwater protection zones…) was performed to identify and collect available field-based measurements for a statistical description and analysis of such data. Complementary to that, a simple geodatabase has been developed to manage and process these data. As expected, these results show contrasted parameter distributions per geological contexts and regions. The objective of the presentation is to describe the methodology followed for the statistical treatment of hydrogeological data and to present the results and associated database. It is believed that such results can be very useful for different hydrogeological studies, in particular as a first referential for groundwater modelling applications and any other studies where statistical descriptions of hydrogeological data are relevant. [less ▲]

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See detailConvention Région wallonne et HGE-ULg Caractérisation complémentaire des masses d’eau dont le bon état dépend d’interactions entre les eaux de surface et les eaux souterraines - Délivrable D1.8 Rapport final
Brouyère, Serge ULiege; Briers, Pierre ULiege; Descy, Jean-Pierre et al

Report (2017)

Mechanisms of interactions between groundwater bodies and rivers whose status and anthropogenic use can be detrimental from a quantitative and qualitative point of view to one or the other of these two ... [more ▼]

Mechanisms of interactions between groundwater bodies and rivers whose status and anthropogenic use can be detrimental from a quantitative and qualitative point of view to one or the other of these two compartments of the water cycle. In addition, contamination of groundwater by nitrate remains relevant. Based on these observations, a study financed by the Public Service of Wallonia was carried out over a period of 39 months to investigate (1) the direction, importance and dynamics of water exchange between groundwater and rivers at the scale of a river section; (2) the impact of these interactions on river baseflows and the river ecological status as a function of groundwater withdrawal and recharge at the catchment scale; (3) mechanisms and timing of transfer and abatement of pollutants (nitrate) between groundwater and surface waters at the watershed scale. The consequences of these mechanisms on the medium- and long-term evolution of groundwater and surface water quality were to be determined. To achieve this, the project relied on the implementation of a series of field investigations essentially focused on the interfaces between surface water and groundwater compartments (soil and unsaturated zone and water-table interface), while acquiring additional information on groundwater. The investigations carried out in the watersheds of the upstream Hoyoux and Triffoy watershed in the Condroz region aimed to provide 6 specific responses to water quantity and quality issued associated with groundwater – surface water interactions in the selected basins and generic responses in the form of new knowledge concerning the mechanisms of recharge and groundwater - river exchanges, concerning the evolution of nitrate concentrations in watersheds, data and measurements for the parameterization of models, and water resources management tools in the form of quantitative and qualitative indicators for groundwater - surface water interactions. [less ▲]

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See detailStream-aquifer interactions: a combined field - methodological approach in fractured carbonate catchments
Brouyère, Serge ULiege; Briers, Pierre ULiege; Orban, Philippe ULiege et al

Conference (2016, December 16)

Stream-aquifer studies remain a challenge due to numerous factors impacting these interactions. They play a fundamental role in terms of quantity and quality of water, in particular on the ecological ... [more ▼]

Stream-aquifer studies remain a challenge due to numerous factors impacting these interactions. They play a fundamental role in terms of quantity and quality of water, in particular on the ecological status of rivers. Field quantification of such interactions is a first step but it has to be in relation with the whole budgets of water and transported substances across the catchment in order to represent their importance on overall fluxes. Numerous complementary investigations have to be undertaken to achieve such understanding of catchment behavior, in particular to estimate specific indicators and to achieve representative data for modeling stream-aquifer interactions. From that situation, our study aims to characterize and quantify stream-aquifer interactions to assess reliability of diverse field experiments methodologies. A catchment has been studied for 3 years in quantitative and qualitative ways via a dense instrumentation and monitoring. Numerous complementary investigations (discharge measurements, hydrogeochemistry, distributed temperature sensing, base flow separation…) have been applied to reach the objectives. We achieved a large and diversified measurement dataset of groundwater-surface water interactions and whole water budget. This allowed reaching an improved understanding of the catchment behavior to quantify importance of the groundwater component on the dynamics and chemistry of the stream and on the consequences on river ecological status. The investigations on several subcatchments allows also to propose a general typology of stream catchment in terms of groundwater dependence based on the combination of various groundwater contexts and groundwater-stream interaction indicators. Methodologies applied in this study allow to emphasize strength and weakness of numerous investigations in a stream aquifer project and conclusions can be reproduced and generalized to other contexts. [less ▲]

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See detailNitrate dynamic and pathways in fractured limestone aquifers : From soil leaching to groundwater discharge in surface water
Briers, Pierre ULiege; Schmit, Flore; Orban, Philippe ULiege 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 detailLe bassin du Triffoy et les eaux souterraines : Exemple de caractérisation des échanges entre nappe et rivière
Briers, Pierre ULiege; Descy, Jean-Pierre; Schmit, Flore et al

in Atlas du Karst Wallon - Bassins versants du Hoyoux et de la Solières (2016)

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See detailVégétation du ruisseau du Triffoy et du Hoyoux près du moulin de Roiseux
Bouxin, Guy; Briers, Pierre ULiege; Michel, Georges

in Atlas du Karst Wallon - Bassins versants du Hoyoux et de la Solières (2016)

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See detailHydrogéologie du bassin du Hoyoux
Briers, Pierre ULiege; Jamin, Pierre ULiege; Ruthy, Ingrid ULiege et al

in Atlas du Karst Wallon - Bassins versants du Hoyoux et de la Solières (2016)

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

Report (2016)

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