References of "Dassargues, Alain"
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See detailMethodology for the integration of process studies and development of a decision support tool (FRAC-WECO Project Deliverable D1.2)
Brouyère, Serge ULg; Hérivaux, Cécile; Haberman, Michaël et al

Report (2007)

This deliverable allows one to clarify the objectives of the different partners involved in the FRAC-WECO project and how they are going to interact, to exchange data, research results and knowledge in ... [more ▼]

This deliverable allows one to clarify the objectives of the different partners involved in the FRAC-WECO project and how they are going to interact, to exchange data, research results and knowledge in order to meet the ambitious objectives of the project. Particularly, the complex interactions between researches dealing with physical processes and with socio-economic aspects have been described in details. The modelling applications will constitute the key interacting tools as they are going to integrate all the information on water and contaminant mass fluxes and on biogeochemical processes affecting the fate of contaminant in the field and they are also going to be used to produce all data required for risk assessment and for the socio-economic analysis which are two of the most important expected outcomes of the project. The deliverable also clarifies the use of flux-based concepts through the definition of risk assessment indicators in the form of contaminant mass fluxes and discharge at the various considered receptors. Finally, this document has also allowed one to clarify the scope and the limits of the researches foreseen in the FRAC-WECO project that will focus on the risk of contaminant leaching to groundwater, of contaminant dispersion through groundwater and on the impact of contaminant on groundwater and surface water as affected by groundwater discharge and on the impact on aquatic ecosystems. [less ▲]

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See detailCarte hydrogéologique de Harzé - La Gleize 49/7-8, 1/25.000 : [notice explicative]
Ruthy, Ingrid ULg; Dassargues, Alain ULg

Book published by Ministère de la Région wallonne, DGRNE - Edition provisoire : septembre 2007 (2007)

Detailed reference viewed: 57 (8 ULg)
See detailCarte hydrogéologique de Wallonie, Harzé - La Gleize 49/7-8
Ruthy, Ingrid ULg; Dassargues, Alain ULg

Cartographic material (2007)

Detailed reference viewed: 81 (11 ULg)
See detailCarte hydrogéologique de Wallonie, Durbuy - Mormont 55/1-2
Ruthy, Ingrid ULg; Dassargues, Alain ULg

Cartographic material (2007)

Detailed reference viewed: 82 (7 ULg)
See detailCarte hydrogéologique de Wallonie, Bra - Lierneux 55/3-4
Ruthy, Ingrid ULg; Dassargues, Alain ULg

Cartographic material (2007)

Detailed reference viewed: 34 (1 ULg)
See detailCarte hydrogéologique, Bra - Lierneux 55/3-4, 1/25.000 : [notice explicative]
Ruthy, Ingrid ULg; Dassargues, Alain ULg

Book published by Ministère de la Région wallonne, Direction générale des ressources naturelles et de l'environnement - Edition provisoire : août 2007 (2007)

Detailed reference viewed: 22 (3 ULg)
See detailCarte hydrogéologique, Durbuy - Mormont 55/1-2, 1/25.000 : [notice explicative]
Ruthy, Ingrid ULg; Dassargues, Alain ULg

Book published by Ministère de la Région wallonne, DGRNE - Edition provisoire : août 2007 (2007)

Detailed reference viewed: 47 (9 ULg)
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See detailThe effect of heterogeneity on the agreement between analytical and numerical solutions describing the recession flow in unconfined hillslope aquifers
Rocha, David; Feyen, Jan; Dassargues, Alain ULg

in Proceedings of the Int. Congress on Development, Environment and Natural Resources: Multi-level and multi-scale Sustainability (2007, July)

Analytical approximations or linearized versions of the Boussinesq equation, describing recession flow in unconfined hillslope aquifers have been applied extensively in the past. One of the major ... [more ▼]

Analytical approximations or linearized versions of the Boussinesq equation, describing recession flow in unconfined hillslope aquifers have been applied extensively in the past. One of the major assumptions in the conceptual formulation is isotropic homogeneity of the aquifer. Notwithstanding the effect of aquifer heterogeneity on recession flow has been pointed out [1], only recent studies are increasingly focusing on the quantification of this effect [2,3]. In the present research, the relevance of heterogeneity is being studied by analyzing the agreement between analytical approximations and the numerical solution of the receding flow in a layered unconfined aquifer with different domain configurations (horizontal, inclined and concave impervious bedrock). For the application of the analytical approximations use is made of the equivalent hydraulic conductivity concept. [less ▲]

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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 ▲]

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See detailIntermediate report on the development of the Geer hydrological model (surface and subsurface water) for climatic change scenario on that sub-catchment
Goderniaux, Pascal ULg; Orban, Philippe ULg; Dassargues, Alain ULg et al

Report (2007)

In the framework of Workpackage BASIN R3 Meuse, the Hydrology Group of the University of Liège (Belgium) is developing a hydrological model of the Geer sub-catchment, in order to assess climate change ... [more ▼]

In the framework of Workpackage BASIN R3 Meuse, the Hydrology Group of the University of Liège (Belgium) is developing a hydrological model of the Geer sub-catchment, in order to assess climate change impacts on groundwater reserves. This report describes the calculation code used, the general hypotheses chosen to develop the model, the conceptual model, the climate change scenarios and the final objectives of the study. [less ▲]

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See detailEquivalent diffusion coefficient and equivalent diffusion accessible porosity of a stratified porous medium
Huysmans, Marijke; Dassargues, Alain ULg

in Transport in Porous Media (2007), 66(3), 421-438

Diffusion is an important transport process in low permeability media, which play an important role in contamination and remediation of natural environments. The calculation of equivalent diffusion ... [more ▼]

Diffusion is an important transport process in low permeability media, which play an important role in contamination and remediation of natural environments. The calculation of equivalent diffusion parameters has however not been extensively explored. In this paper, expressions of the equivalent diffusion coefficient and the equivalent diffusion accessible porosity normal to the layering in a layered porous medium are derived based on analytical solutions of the diffusion equation. The expressions show that the equivalent diffusion coefficient changes with time. It is equal to the power average with p = -0.5 for small times and converges to the harmonic average for large times. The equivalent diffusion accessible porosity is the harmonic average of the porosities of the individual layers for all times. The expressions are verified numerically for several test cases. [less ▲]

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See detailExploratory data analysis and clustering of multivariate spatial hydrogeological data by means of GEO3DSOM, a variant of Kohonen's Self-Organizing Map
Peeters, Luk; Bacao, R.; Lobo, V. et al

in Hydrology and Earth System Sciences (2007), 11(4), 1309-1321

The use of unsupervised artificial neural network techniques like the self-organizing map (SOM) algorithm has proven to be a useful tool in exploratory data analysis and clustering of multivariate data ... [more ▼]

The use of unsupervised artificial neural network techniques like the self-organizing map (SOM) algorithm has proven to be a useful tool in exploratory data analysis and clustering of multivariate data sets. In this study a variant of the SOM-algorithm is proposed, the GEO3DSOM, capable of explicitly incorporating three-dimensional spatial knowledge into the algorithm. The performance of the GEO3DSOM is compared to the performance of the standard SOM in analyzing an artificial data set and a hydrochemical data set. The hydrochemical data set consists of 131 groundwater samples collected in two detritic, phreatic, Cenozoic aquifers in Central Belgium. Both techniques succeed very well in providing more insight in the groundwater quality data set, visualizing the relationships between variables, highlighting the main differences between groups of samples and pointing out anomalous wells and well screens. The GEO3DSOM however has the advantage to provide an increased resolution while still maintaining a good generalization of the data set. [less ▲]

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Peer Reviewed
See detailComparative analysis between analytical approximations and numerical solutions describing recession flow in unconfined hillslope aquifers
Rocha, David; Feyen, Jan; Dassargues, Alain ULg

in Hydrogeology Journal (2007), 15(6), 1077-1091

Recession flow of aquifers from a hillslope can be described by the non-linear Boussinesq equation. Under strong assumptions and for specific conceptual formulations, different authors derived analytical ... [more ▼]

Recession flow of aquifers from a hillslope can be described by the non-linear Boussinesq equation. Under strong assumptions and for specific conceptual formulations, different authors derived analytical approximations or linearized versions to this partial differential equation. A comparative analysis between some analytical approximations of the Boussinesq equation and the numerical solution of the recession flow of an unconfined homogeneous aquifer (horizontal, inclined and concave aquifer floor) was carried out. The objective was to define the range where the analytical solutions approximate the numerical solution. The latter was considered in this study as the reference method, because it requires fewer assumptions. From the considered analytical approximations, exponential decay relationships were found to be mainly valid for fine domain materials when horizontal, mild slopes (less than 2%) and concave aquifer floors were considered, but failed to reproduce coarse aquifer numerical model outflows, in contrast to the quadratic decay relationship, which better reproduce outflows in such domains. On the basis of the comparative analysis, it has been found that recession flows obtained with the considered analytical approximations yield similar values only for certain ranges of aquifer properties and geometries. [less ▲]

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See detailIntegrated approach for assessing climate change impacts on a regional chalky aquifer in Belgium
Goderniaux, Pascal ULg; Brouyère, Serge ULg; Dassargues, Alain ULg

in Changes in water resource systems: methodologies to maintain water security and ensure integrated management (2007)

An integrated hydrological model was developed in order to study the potential effects of climate change on groundwater resources. This model considers most hydrological processes in a physically ... [more ▼]

An integrated hydrological model was developed in order to study the potential effects of climate change on groundwater resources. This model considers most hydrological processes in a physically consistent way. More particularly, groundwater flows are modelled using a spatially distributed finite element approach. The river-aquifer interactions are explicitly taken into account in the model, as well as the spatial heterogeneity of the chalk geology characteristics. After a detailed calibration on the last 30 years and validation on recent periods, quantitative interpretations can be drawn from the ground¬water model results. Considering IPCC climate change scenarios, it appears that, on a multi-annual basis, most tested scenarios predict a decreasing trend in groundwater levels in the Geer Basin. These first results indicate that groundwater deficits may be expected in the future in Belgium. Moreover, at this stage of the study, this trend is computed for a very “optimistic” scenario, neglecting all other pressure changes on the groundwater resources (i.e. no change in land use and in pumping conditions). [less ▲]

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See detailCombining the generalised likelihood uncertainty estimation (GLUE) and Bayesian model averaging (BMA) to account for conceptual model uncertainty in groundwater modelling
Rojas, Rodrigo; Feyen, Luc; Dassargues, Alain ULg

in Calibration and Reliability in Groundwater Modelling: Credibility in Modelling (Pre-Published Proc. of ModelCARE’2007) (2007)

Detailed reference viewed: 78 (3 ULg)