References of "Orban, Philippe"
     in
Bookmark and Share    
Full Text
See detailEvaluation qualitative et quantitative des ressources en eau souterraine dasn le bassin de Dargol (Liptako – Niger)
Abdou Babaye, Maman Sani ULg; Boureimane, Ousmane; Orban, Philippe ULg et al

Conference (2012, November)

Située dans la partie Sud-Ouest du Niger, le bassin de Dargol appartient à la région de socle précambrien du Liptako. L’étude du chimisme des eaux souterraines révèle trois types de faciès dont le plus ... [more ▼]

Située dans la partie Sud-Ouest du Niger, le bassin de Dargol appartient à la région de socle précambrien du Liptako. L’étude du chimisme des eaux souterraines révèle trois types de faciès dont le plus dominant est le type bicarbonaté calcique à magnésien (65%). Environ 47% d’ouvrages ont des teneurs en nitrates dépassant largement les normes OMS (50 mg/l). Les teneurs en isotopes stables (δ18O, δ2H) de la nappe indiquent deux mécanismes de recharge: une recharge directe par les eaux des pluies peu ou pas évaporées, et une recharge indirecte par les eaux évaporées issues des lits de koris et des eaux de surface. L’analyse des teneurs en tritium de la nappe indique que la recharge est récente pour la majorité des points investigués. En revanche, dans le secteur à faibles teneurs en tritium, le taux de renouvellement semble être faible voire nul. [less ▲]

Detailed reference viewed: 105 (16 ULg)
Full Text
Peer Reviewed
See detailHow tracer tests simulations strongly constrain flow and solute transport models in fractured chalk aquifers
Goderniaux, Pascal ULg; Daoudi, Moubarak; Orban, Philippe ULg et al

Conference (2012, May)

Flow and solute transport in the saturated zone of a micro-fissured and fractured chalk aquifer (Geer basin, Belgium) has been studied by more than 35 tracer tests in 11 sites. The tracer tests campaign ... [more ▼]

Flow and solute transport in the saturated zone of a micro-fissured and fractured chalk aquifer (Geer basin, Belgium) has been studied by more than 35 tracer tests in 11 sites. The tracer tests campaign was preceded by a morphostructural study associated to a geophysical survey including electrical resistivity and refraction seismic measurements. Results provided information on the main expected fracturation axis where a series of injection and monitoring wells were drilled. In each of the 11 sites, multi-tracer tests have been performed in groundwater convergent flow conditions to pumping wells or draining galleries (used for drinking water production). The analysis of the detailed quantitative breakthrough curves allowed identifying various transport behaviours, from rapid advective to dominant dispersive processes with immobile water effects. Groundwater flow and solute transport in such a fractured chalk can be simulated using different conceptual approaches. Using HYDROGEOSPHERE (Therrien and Sudicky, 1996), a comparison is made between two ways for representing the fracture zones: (1) high contrasted hydraulic conductivity zones with a classical REV approach and (2) the explicit representation of discrete fractures interacting with a porous medium. Promising results are found using the discrete approach for representing the fractures. In this last case, an aperture of the order of the millimetre is enough for creating, where it is needed, a fast advective peak combined with a long highly dispersive component due to the chalk matrix. The discrete fracture approach prevents the modeller from introducing unrealistic parameters values in the fracture zones as it is generally the case in the classical REV-based method where the fractured zones are simply represented by elongated REV. However, it is shown that the availability of field data, as multi-tracers test results, creates very high constraints to be taken into account in the calibration processes (i.e calibration on the measured groundwater flow and transport conditions). The detailed calibration on the different breakthrough curves is not an easy task and automatic calibration is not easy to organize. Results are particularly illustrative to show that a detailed parameterization and calibration of such a local situation remain difficult. Perspectives will be discussed about the potential use of automatic calibration tools as UCODE_2005 or PEST for solving such local situation models and the needed further steps for ‘upscaling’ local situation models at the scale of the whole aquifer or groundwater body. [less ▲]

Detailed reference viewed: 84 (14 ULg)
Full Text
Peer Reviewed
See detailA regional flux-based risk assessment approach for multiple contaminated sites on groundwater bodies
Jamin, Pierre ULg; Dollé, Fabien ULg; Chisala, Brenda et al

in Journal of Contaminant Hydrology (2012), 127(1-4), 65-75

In the context of the Water Framework Directive (EP and CEU, 2000), management plans have to be set up to monitor and to maintain water quality in groundwater bodies in the EU. In heavily industrialized ... [more ▼]

In the context of the Water Framework Directive (EP and CEU, 2000), management plans have to be set up to monitor and to maintain water quality in groundwater bodies in the EU. In heavily industrialized and urbanized areas, the cumulative effect of multiple contaminant sources is likely and has to be evaluated. In order to propose adequate measures, the calculated risk should be based on criteria reflecting the risk of groundwater quality deterioration, in a cumulative manner and at the scale of the entire groundwater body. An integrated GIS- and flux-based risk assessment approach for groundwater bodies is described, with a regional scale indicator for evaluating the quality status of the groundwater body. It is based on the SEQ-ESO currently used in the Walloon Region of Belgium which defines, for different water uses and for a detailed list of groundwater contaminants, a set of threshold values reflecting the levels of water quality and degradation with respect to each contaminant. The methodology is illustrated with first results at a regional scale on a groundwater body-scale application to a contaminated alluvial aquifer which has been classified to be at risk of not reaching a good quality status by 2015. These first results show that contaminants resulting from old industrial activities in that area are likely to contribute significantly to the degradation of groundwater quality. However, further investigations are required on the evaluation of the actual polluting pressures before any definitive conclusion be established. [less ▲]

Detailed reference viewed: 91 (36 ULg)
Full Text
See detailFlux-based Risk Assessement of the impact of Contaminants on Water resources and ECOsystems
Jamin, Pierre ULg; Dujardin, Juliette; Crèvecoeur, Sophie et al

Report (2012)

Detailed reference viewed: 36 (7 ULg)
See detailFlux-based risk assessment of the impact of contamnants on water ressources and ecosystems - FRAC-WECO.
Jamin, Pierre ULg; Dujardin, J.; Crévecoeur, Sophie et al

Report (2012)

Detailed reference viewed: 41 (5 ULg)