Browsing
     by title


0-9 A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

or enter first few letters:   
OK
Full Text
Peer Reviewed
See detailGroundwater flow modelling of the regional aquifer of the Pampa del Tamarugal, northern Chile
Rojas, Rodrigo; Dassargues, Alain ULg

in Hydrogeology Journal (2007), 15(3), 537-551

The Pampa del Tamarugal Aquifer (PTA) is an important source of groundwater in northern Chile. In this study, a groundwater flow model of this aquifer is developed and calibrated for the period 1983-2004 ... [more ▼]

The Pampa del Tamarugal Aquifer (PTA) is an important source of groundwater in northern Chile. In this study, a groundwater flow model of this aquifer is developed and calibrated for the period 1983-2004. The model reproduces the observed flow-field and the water balance components reasonably well. Five scenarios are defined to evaluate the response to different pumping situations. These scenarios show that groundwater heads will continue to decrease with the present pumping discharge rates. To account for variations in the model results due to uncertainties in average recharge rates, randomly generated recharge realizations with different levels of uncertainty are simulated. Evaporation flow rates and groundwater flowing out of the modelled area seem unaffected by the recharge uncertainty, whereas the storage terms can vary considerably. For the most intensive pumping scenario under the generated random recharge rates, it is unlikely that the cumulative discharged volume from the aquifer, at the end of the simulation period, will be larger than 12% of the estimated groundwater reserve. Fluctuations in simulated groundwater heads due to uncertainties in the average recharge values are more noticeable in certain areas. These fluctuations could explain unusual behaviour in the observed groundwater heads in these areas. [less ▲]

Detailed reference viewed: 89 (19 ULg)
Full Text
See detailGroundwater issues create challenges for engineers
Dassargues, Alain ULg

Scientific conference (2012, June 15)

Detailed reference viewed: 7 (0 ULg)
Full Text
See detailGroundwater model parameter identification using a combination of cone-penetration tests and borehole data
Rogiers, Bart; Schiltz, Marco; Beerten, Koen et al

in International Groundwater Symposium 2010, IAHR (2010, September)

In the framework of the disposal of short-lived low- and intermediate-level radioactive waste in a near-surface disposal facility in Dessel, Belgium, additional extensive site characterisation has been ... [more ▼]

In the framework of the disposal of short-lived low- and intermediate-level radioactive waste in a near-surface disposal facility in Dessel, Belgium, additional extensive site characterisation has been performed in 2008. The gathered data now include 388 hydraulic conductivity measurements on samples from 8 cored boreholes. Detailed characterisation of these cored boreholes, together with geophysical logging, enabled to identify various hydrostratigraphical units at 8 discrete locations in the research area. Various analyses were performed on the cores, yielding information on grain size, mineralogy, density and total porosity. Geophysical logging parameters were derived from gamma-ray and resistivity measurements. Subsequently, an extensive geotechnical logging campaign was performed in order to establish a 3D-model of the hydrostratigraphical units, based on a dense network of investigation points. About 180 cone penetration tests (CPTs) were executed and lithology was deduced in detail based on existing soil classi cation charts. As such, a description of the regional subsurface up to depths of nearly 50 m was established, and this information was integrated with the borehole data. Most importantly, the lateral extent, depth and thickness of a hydrogeologically important aquitard was identi fied. Based on the 2008 site characterisation results and their interpretation, an update of a ground- water fl ow model used in safety assessments was made. The CPT-based stratigraphic model and the hydraulic conductivity data determined at different scales were combined into a new 3D hydrostratigraphical model. The small-scale measurements (on 100 cm³ core samples) are compared with hydraulic conductivity values obtained from pumping tests and the large-scale parameters derived by inverse modelling. The performance of the original and the updated flow model are compared. The presented approach was succesfull in substantially decreasing the conceptual model and parameter uncertainty and resulted in an improved calibration of the groundwater flow model. [less ▲]

Detailed reference viewed: 106 (16 ULg)
Full Text
See detailGroundwater modelling to predict the impact of a tunnel on the behaviour of a water table aquifer in urban conditions
Dassargues, Alain ULg

in Chilton, J. (Ed.) Groundwater in the Urban Environment : Problems, Processes and Management, Proc. of XXVII IAH Congress (1997)

Detailed reference viewed: 23 (3 ULg)
Full Text
Peer Reviewed
See detailGroundwater pollution in an agricultural catchment on sandstone : evaluation of water and nitrogen losses from soils.
Lecomte, Marielle; Salvia, Merce; Iffly, Jean-François et al

Conference (2000)

Detailed reference viewed: 4 (1 ULg)
Full Text
Peer Reviewed
See detailGroundwater quality assessment of one former industrial site in Belgium using a TRIAD-like approach.
Crévecoeur, Sophie; Debacker, Virginie ULg; Joaquim-Justo, Célia ULg et al

in Environmental Pollution (2011), 159(10), 2461-2466

Contaminated industrial sites are important sources of pollution and may result in ecotoxicological effects on terrestrial, aquatic and groundwater ecosystems. An effect-based approach to evaluate and ... [more ▼]

Contaminated industrial sites are important sources of pollution and may result in ecotoxicological effects on terrestrial, aquatic and groundwater ecosystems. An effect-based approach to evaluate and assess pollution-induced degradation due to contaminated groundwater was carried out in this study. The new concept, referred to as “Groundwater Quality TRIAD-like” (GwQT) approach, is adapted from classical TRIAD approaches. GwQT is based on measurements of chemical concentrations, laboratory toxicity tests and physico-chemical analyses. These components are combined in the GwQT using qualitative and quantitative (using zero to one subindices)integration approaches. The TRIAD approach is applied for the first time on groundwater from one former industrial site located in Belgium. This approach will allow the classification of sites into categories according to the degree of contaminant-induced degradation. This new concept is a starting point for groundwater characterization and is open for improvement and adjustment. [less ▲]

Detailed reference viewed: 41 (14 ULg)
Full Text
See detailGroundwater quality mapping in the Belgian and Dutch provinces of Limburg and Liège: availability of data and methodology
Dassargues, Alain ULg; Peters, Valérie; Rutten, J. et al

in Proc. of the Int. Conf. on Quality, Management and Availability of Data for Hydrology and Water Resources Management (1999)

Detailed reference viewed: 38 (2 ULg)
Full Text
Peer Reviewed
See detailGroundwater vulnerability assessment using physically based modelling: from challenges to pragmatic solutions
Popescu, Ileana Cristina; Gardin, Nicolas; Brouyère, Serge ULg et al

in Refsgaard, J. C.; Kovar, K.; Haarder, E. (Eds.) et al Calibration and Reliability in Groundwater Modelling: Credibility in Modelling (2008)

Numerous groundwater vulnerability and risk mapping techniques have been developed taking into consideration a variable number of factors. The most common techniques are based on calculation of an index ... [more ▼]

Numerous groundwater vulnerability and risk mapping techniques have been developed taking into consideration a variable number of factors. The most common techniques are based on calculation of an index expressing the protective effect of underground formations overlying the groundwater resource. The limitation of most of these methods is related to their use of a qualitative definition of groundwater vulnerability, as opposed to a definition based on a quantitative description of contaminant migration. A physically-based point of view and definition of the vulnerability is proposed and based on three factors describing a pollution event, which are the contaminant transfer time from the hazard location to the 'target', the contamination duration at the 'target' and the level of contaminant concentration reached at the 'target'. This concept allows a clear distinction between conventional aspects and physically-based results in the building of a final vulnerability indicator. This methodology has the further advantage to consider the possible impact of runoff conditions occurring at the land surface and possibly leading to lateral contamination of groundwater through downstream preferential infiltration features. Practically, this method needs to describe and simulate the pollutant migration in the unsaturated zone and possibly in the saturated zone in order to assess the breakthrough curve at the 'target'. Preliminary application is illustrated on a case-study located in a limestone basin in Belgium. Perspectives are proposed towards a generalisation of the vulnerability concept for risk assessment within a pressure - state - impact framework. [less ▲]

Detailed reference viewed: 244 (28 ULg)
See detailGroup B Streptococcal Disease in Belgium: Culture and Rapid screening
MELIN, Pierrette ULg

Conference (1999, February 25)

Detailed reference viewed: 5 (0 ULg)
Full Text
See detailGroup B Streptococcal Disease in the Newborn: Maternal GBS-Screening Methods and Antimicrobial Prophylaxis
Melin, Pierrette ULg

in European Obstetrics and Gynaecology - Touch Briefings (2008), 3

Detailed reference viewed: 18 (4 ULg)
Full Text
Peer Reviewed
See detailGroup B streptococcal epidemiology and vaccine needs in developed countries
MELIN, Pierrette ULg; EFSTRATIOU, Androulla

in Vaccine (2013), 31(Supplement 4), 31-42

Development of a group B streptococcal vaccine (GBS) vaccine is the most promising approach for the prevention of GBS infections in babies, given the potential adverse effects of intrapartum antibiotic ... [more ▼]

Development of a group B streptococcal vaccine (GBS) vaccine is the most promising approach for the prevention of GBS infections in babies, given the potential adverse effects of intrapartum antibiotic prophylaxis as well as the need for effective prevention of both adult and late perinatal disease. There are numerous prevention strategies at this time but none are 100% effective in the eradication of neonatal early onset GBS disease and there are no preventative strategies for late onset disease. The need for a GBS vaccine is therefore, of utmost importance. Efforts applying genomics to GBS vaccine development have led to the identification of novel vaccine candidates. The publication of GBS whole genomes coupled with new technologies including multigenome screening and bioinformatics has also allowed researchers to overcome the serotype limitation of earlier vaccine preparations in the search of a universal effective vaccine against GBS. This review brings together the key arguments concerning the potential need of a GBS vaccine in developed countries and describes the current status with GBS epidemiology and microbiology in these countries. [less ▲]

Detailed reference viewed: 22 (3 ULg)
See detailGroup B Streptococcal infections
MELIN, Pierrette ULg

Scientific conference (2001, November 17)

Detailed reference viewed: 7 (0 ULg)
See detailGroup B Streptococcal infections in Belgium
MELIN, Pierrette ULg

Conference (2001, December)

Detailed reference viewed: 9 (0 ULg)
See detailGroup B Streptococcal Infections in Belgium
MELIN, Pierrette ULg

Conference (2001, November 30)

Detailed reference viewed: 8 (0 ULg)
See detailGroup B Streptococcal Infections in Belgium
Melin, Pierrette ULg

Conference (2002, March 13)

Detailed reference viewed: 6 (0 ULg)
See detailGroup B streptococcal policies in the French Community of Belgium
MELIN, Pierrette ULg

Scientific conference (2001, November 17)

Detailed reference viewed: 7 (0 ULg)
See detailGroup B streptococcal Screening
MELIN, Pierrette ULg

Scientific conference (2001, November 17)

Detailed reference viewed: 5 (0 ULg)
Full Text
See detailGroup B streptococcal Screening, Diagnosis and Clinically Relevant Resistance
Melin, Pierrette ULg

Conference (2010, June 17)

In the setting of a maternal GBS-screening program and successful implementation of the strategy, efforts to improve screening for GBS status remain important. Critical factors that influence the accuracy ... [more ▼]

In the setting of a maternal GBS-screening program and successful implementation of the strategy, efforts to improve screening for GBS status remain important. Critical factors that influence the accuracy of detecting GBS maternal colonization are the choice of culture media, the body sites sampled, and the timing of sampling. The evolution of the different culture options to improve the GBS-screening strategy will be reviewed. Despite efforts related to sampling and culture procedures, false-negative GBS-screening contributing to continuing EOGBS cases and false-positive screening leading to unecessary IAP, occur. As GBS carriage is highly variable, the predictive values of GBS antenatal cultures are not always good predictors of the maternal GBS status at presentation for delivery. Rapid non-cultural GBS screening methods have been developed: antigenic tests are not sensitive enough to replace antenatal screening cultures but available real-time PCR have faired better in the detection of GBS. Real-time PCR tests could improve effectiveness of the screening-based strategy and lead to a further reduction of the incidence of EOGBS disease. However questions of costs and logistics remain unanswered. Either for therapy or for intrapartum chemoprophylaxis, penicillin G for its bactericidal activity and narrow spectrum, remains the agent of choice. But in the true penicillin allergic patients, clindamycin or erythromycin have been recommended as alternative drugs. However, probably as a consequence of the important use of macrolides, related drug resistance among streptococcal isolates is currently recognized in many countries. Epidemiology of resistance to antimicrobial agents will be presented. [less ▲]

Detailed reference viewed: 45 (2 ULg)
Full Text
See detailGroup B streptococcal Screening, Diagnosis and Clinically Relevant Resistance
Melin, Pierrette ULg

in DEVANI Training (Ed.) European Workshop Current Insights into Group B Streptococcal Diseases (2009, May)

Detailed reference viewed: 11 (5 ULg)