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See detailLarge-scale flow and transport modelling for the management of groundwater bodies: the Geer case-study
Orban, Philippe ULg; Goderniaux, Pascal ULg; Brouyère, Serge ULg

in AquaTerra Final Conference. Programme & Proceedings (2009, March)

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See detailThe Hybrid Finite Element Mixing Cell Method: A New Flexible Method for Modelling Mine Ground Water Problems
Brouyère, Serge ULg; Orban, Philippe ULg; Wildemeersch, Samuel ULg et al

in Mine Water & the Environment (2009), 28(2), 102-114

Dewatering operations often stop at mine closure. The ground water rebound can have undesirable consequences, which numerical models can help one understand and manage. However, classical modelling ... [more ▼]

Dewatering operations often stop at mine closure. The ground water rebound can have undesirable consequences, which numerical models can help one understand and manage. However, classical modelling techniques are relatively unsuitable to these contexts. While spatially-distributed and physically-based models suffer difficulties due to the lack of data and the complexity of geological and hydrogeological conditions, black-box models are too simple to deal with the problems effectively. A new modelling method is proposed to simulate ground water environments in which water flows through mined (exploited) and unmined (unexploited) areas. Exploited zones are simulated using a group of mixing cells possibly interconnected by pipes. Unexploited zones are simultaneously simulated using classical finite elements. This combined approach allows explicit calculation of ground water flows around the mine and mean water levels in the exploited zones. Water exchanges between exploited zones and unexploited zones are simulated in the model using specifically-defined internal boundary conditions. The method is tested on synthetic cases of increasing complexity, and first results from a real case study are presented. [less ▲]

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See detailComparison of methods for the detection and extrapolation of trends in groundwater quality
Visser, Ate; Dubus, Igor; Broers, Hans Peter et al

in Journal of Environmental Monitoring (2009)

Land use changes and the intensification of agriculture since the 1950s have resulted in a deterioration of groundwater quality in many European countries. For the protection of groundwater quality, it is ... [more ▼]

Land use changes and the intensification of agriculture since the 1950s have resulted in a deterioration of groundwater quality in many European countries. For the protection of groundwater quality, it is necessary to (1) assess the current groundwater quality status, (2) detect changes or trends in groundwater quality, (3) assess the threat of deterioration and (4) predict future changes in groundwater quality. A variety of approaches and tools can be used to detect and extrapolate trends in groundwater quality, ranging from simple linear statistics to distributed 3D groundwater contaminant transport models. In this paper we report on a comparison of four methods for the detection and extrapolation of trends in groundwater quality: (1) statistical methods, (2) groundwater dating, (3) transfer functions, and (4) deterministic modeling. Our work shows that the selection of the method should firstly be made on the basis of the specific goals of the study (only trend detection or also extrapolation), the system under study, and the available resources. For trend detection in groundwater quality in relation to diffuse agricultural contamination, a very important aspect is whether the nature of the monitoring network and groundwater body allows the collection of samples with a distinct age or produces samples with a mixture of young and old groundwater. We conclude that there is no single optimal method to detect trends in groundwater quality across widely differing catchments. [less ▲]

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See detailLarge scale surface – subsurface hydrological model to assess climate change impacts on groundwater reserves
Goderniaux, Pascal ULg; Brouyère, Serge ULg; Fowler, Hayley J. et al

in Journal of Hydrology (2009), 373

Estimating the impacts of climate change on groundwater represents one of the most difficult challenges faced by water resources specialists. One difficulty is that simplifying the representation of the ... [more ▼]

Estimating the impacts of climate change on groundwater represents one of the most difficult challenges faced by water resources specialists. One difficulty is that simplifying the representation of the hydrological system often leads to discrepancies in projections. This study provides an improved methodology for the estimation of the impacts of climate change on groundwater reserves, where a physically-based surface – subsurface flow model is combined with advanced climate change scenarios for the Geer basin (465 km²), Belgium. Coupled surface–subsurface flow is simulated with the finite element model HydroGeoSphere. The simultaneous solution of surface and subsurface flow equations in HydroGeoSphere, as well as the internal calculation of the actual evapotranspiration as a function of the soil moisture at each node of the defined evaporative zone, improve the representation of interdependent processes like recharge, which is crucial in the context of climate change. More simple models or externally coupled models do not provide the same level of realism. Fully integrated surface – subsurface flow models have recently gained attention, but have not been used in the context of climate change impact studies. Climate change simulations were obtained from 6 regional climate model (RCM) scenarios assuming the SRES A2 emission (medium-high) scenario. These RCM scenarios were downscaled using a quantile mapping bias-correction technique that, rather than applying a correction only to the mean, forces the probability distributions of the control simulations of daily temperature and precipitation to match the observed distributions. The same corrections are then applied to RCM scenarios for the future. Climate change scenarios predict hotter and drier summer and warmer and wetter winters. The combined use of an integrated surface – subsurface modelling approach, a spatial representation of the evapotranspiration processes and sophisticated climate change scenarios improves the model realism and projections of climate change impacts on groundwater reserves. For the climatic scenarios considered, the integrated flow simulations show that significant decreases are expected in the groundwater levels (up to 8 meters) and in the surface water flow rates (between 9% and 33%) by 2080. [less ▲]

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See detailBenzene dispersion and natural attenuation in an alluvial aquifer with strong interactions with surface water
Batlle-Aguilar, Jordi; Brouyère, Serge ULg; Dassargues, Alain ULg et al

in Journal of Hydrology (2009)

Field and laboratory investigations have been conducted at a former coke plant, in order to assess pollutant attenuation in a contaminated alluvial aquifer, discharging to an adjacent river. Various ... [more ▼]

Field and laboratory investigations have been conducted at a former coke plant, in order to assess pollutant attenuation in a contaminated alluvial aquifer, discharging to an adjacent river. Various organic (BTEX, PAHs, mineral oils) and inorganic (As, Zn, Cd) compounds were found in the aquifer in concentrations exceeding regulatory values. Due to redox conditions of the aquifer, heavy metals were almost immobile, thus not posing a major risk of dispersion off-site the brownfield. Field and laboratory investigations demonstrated that benzene, among organic pollutants, presented the major worry for off-site dispersion, mainly due to its mobility and high concentration, i.e. up to 750 mg L 1 in the source zone. However, benzene could never be detected near the river which is about 160 m downgradient the main source. Redox conditions together with benzene concentrations determined in the aquifer have suggested that degradation mainly occurred within 100 m distance from the contaminant source under anoxic conditions, and most probably with sulphate as main oxidant. A numerical groundwater flow and transport model, calibrated under transient conditions, was used to simulate benzene attenuation in the alluvial aquifer towards the Meuse River. The mean benzene degradation rate used in the model was quantified in situ along the groundwater flow path using compound-specific carbon isotope analysis (CSIA). The results of the solute transport simulations confirmed that benzene concentrations decreased almost five orders of magnitude 70 m downgradient the source. Simulated concentrations have been found to be below the detection limit in the zone adjacent to the river and consistent with the absence of benzene in downgradient piezometers located close to the river reported in groundwater sampling campaigns. In a transient model scenario including groundwater–surface water dynamics, benzene concentrations were observed to be inversely correlated to the river water levels, leading to the hypothesis that benzene dispersion is mainly controlled by natural attenuation. [less ▲]

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See detailMobility, turnover and storage of pollutants in soils, sediments and waters: achievements and results of the EU project AquaTerra. A review
Barth, J. A. C.; Grathwohl, P.; Fowler, H. J. et al

in Agronomy for Sustainable Development (2009), 29(1), 161-173

AquaTerra is one of the first environmental projects within the 6th Framework program by the European Commission. It began in June 2004 with a multidisciplinary team of 45 partner organizations from 13 EU ... [more ▼]

AquaTerra is one of the first environmental projects within the 6th Framework program by the European Commission. It began in June 2004 with a multidisciplinary team of 45 partner organizations from 13 EU countries, Switzerland, Serbia, Romania and Montenegro. Results from sampling and modeling in 4 large river basins (Ebro, Danube, Elbe and Meuse) and one catchment of the Brévilles Spring in France led to new evaluations of diffuse and hotspot input of persistent organic and metal pollutants including dynamics of pesticides and polycyclic aromatic hydrocarbons, as well as metal turnover and accumulation. While degradation of selected organic compounds could be demonstrated under controlled conditions in the laboratory, turnover of most persistent pollutants in the field seems to range from decades to centuries. First investigations of long-term cumulative and degradation effects, particularly in the context of climate change, have shown that it is also necessary to consider the predictions of more than one climate model when trying to assess future impacts. This is largely controlled by uncertainties in climate model responses. It is becoming evident, however, that changes to the climate will have important impacts on the diffusion and degradation of pollutants in space and time that are just at the start of their exploration. [less ▲]

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See detailAssessing and aggregating trends in groundwater bodies. Examples of the FP VI Aquaterra-project
Broers, Hans-peter; Visser, Ate; Brouyère, Serge ULg et al

in EU Groundwater Policy Development - Good Status Objectives and Integrated management planning (2008, November)

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See detailDraft overview paper on trend analysis in groundwater summarizing the main results of TREND2 in relation to the new Groundwater Directive
Broers, H.P.; Visser, A.; Bierkens, M.F.P. et al

Report (2008)

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