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See detailStudy on the relationship between lineaments and borehole specific capacity in a fractured and karstified limestone area in Vietnam
Tam, V. T.; De Smedt, F.; Batelaan, Okke et al

in Hydrogeology Journal (2004), 12(6), 662-673

For a karstified limestone area in NW Vietnam, the relationship between the distribution of lineaments and borehole specific capacity is determined, resulting in the conclusion that not only the borehole ... [more ▼]

For a karstified limestone area in NW Vietnam, the relationship between the distribution of lineaments and borehole specific capacity is determined, resulting in the conclusion that not only the borehole geomorphological-hydrogeological position but also the lineament distribution influences the specific capacity. No significant spatial well yield patterns are evident in this highly fractured-karstified region. The supposition is that lineaments caused by geotectonic activities affect the local variability in borehole specific capacity. Sixteen pumping tests in conjunction with a comprehensive lineament analysis are used to prove this relationship. The boreholes and lineaments are classified into two groups according to their similarity in geomorphological-hydrogeological features. Lineaments tend to be less detectable in discharge areas (lowland, wide and flat valleys) in contrast to the high density in recharge areas (highland narrow-mountainous ravines). In addition, the presence of a stream network in the former can act as a recharge source to the underlain karstic groundwater system. Consequently, boreholes that are in the discharge areas with a lower density of lineaments often produce high yield. For recharge areas with a high density of lineaments, a good correlation is found between lineament density and borehole specific capacity. [less ▲]

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See detailModelling seasonal variations in nitrate and sulphate concentrations in a vulnerable alluvial aquifer
Peeters, Luk; Haerens, Bruno; Van der Sluys, Jan et al

in Environmental Geology (2004), 46(6-7), 951-961

The Eisden-Meeswijk region in Belgium has been affected by mining subsidence due to the deep coal mining activities. Groundwater levels in the alluvial plain of the Meuse River are maintained below the ... [more ▼]

The Eisden-Meeswijk region in Belgium has been affected by mining subsidence due to the deep coal mining activities. Groundwater levels in the alluvial plain of the Meuse River are maintained below the ground surface by drainage installations and municipal well fields. A correlation between the water level in the Meuse River and the variation in nitrate and sulphate concentrations in the aquifer has been observed. A transient groundwater model is developed for the period May 1998-May 2002 and advective transport simulations have been carried out using this model. During dry periods, the major groundwater flow is directed towards the Meuse River, thereby feeding the river. During wet periods, however, groundwater flows in the opposite direction. Due to these variations in groundwater flow direction and to the extraction of groundwater, zones of higher solute concentration exist of which the position and extension vary both spatially and temporally. [less ▲]

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See detailCharacterization of a cavern conduit system in Vietnam by time series correlation, cross-spectrum and wavelet analyses
Tam, V. T.; De Smedt, F.; Batelaan, Okke et al

in Hydrological Sciences Journal = Journal des Sciences Hydrologiques (2004), 49(5), 879-900

Time series analyses are applied to characterize the transient flow regimes of the Nam La cavern conduit, northwest Vietnam. The conduit transforms the input signal to an output signal, and the degree of ... [more ▼]

Time series analyses are applied to characterize the transient flow regimes of the Nam La cavern conduit, northwest Vietnam. The conduit transforms the input signal to an output signal, and the degree of transformation provides information on the nature of the flow system. The input for the analysis is net precipitation and the flow hydrograph at the cave entrance, while the output series is the flow hydrograph at the resurgence. Cross-correlation and cross-spectrum analysis are used to investigate the stationarity and linearity of the input-output transformation of the system, resulting in hydrodynamic properties such as system memory, response time, and mean delay between input and output. It is shown that during high flow periods, the flow in the conduit is pressurized. Consequently, the linear input-output assumption holds only for low flows. To highlight the hydrodynamics of the cavern conduit for the high flow periods, wavelet spectrum and wavelet cross-spectrum analyses are applied. [less ▲]

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See detailModelling groundwater flow and solute transport in karstic systems: from dreams to the reality – how can models help for groundwater vulnerability assessment ?
Dassargues, Alain ULg

in Proceedings of Trans-Karst 2004, International Transdisciplinary Conference on Development and Conservation of Karst Regions (2004, September)

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See detailMigration of contaminants through the unsaturated zone overlying the Hesbaye chalky aquifer in Belgium: a field investigation
Brouyère, Serge ULg; Dassargues, Alain ULg; Hallet, Vincent

in Journal of Contaminant Hydrology (2004), 72(1-4), 135-164

This paper presents the results of a detailed field investigation that was performed for studying groundwater recharge processes and solute downward migration mechanisms prevailing in the unsaturated zone ... [more ▼]

This paper presents the results of a detailed field investigation that was performed for studying groundwater recharge processes and solute downward migration mechanisms prevailing in the unsaturated zone overlying a chalk aquifer in Belgium. Various laboratory measurements were performed on core samples collected during the drilling of boreholes in the experimental site. In the field, experiments consisted of well logging, infiltration tests in the unsaturated zone, pumping tests in the saturated zone and tracer tests in both the saturated and unsaturated zones. Results show that gravitational flows govern groundwater recharge and solute migration mechanisms in the unsaturated zone. In the variably saturated chalk, the migration and retardation of solutes is strongly influenced by recharge conditions. Under intense injection conditions, solutes migrate at high speed along the partially saturated fissures, downward to the saturated zone. At the same time, they are temporarily retarded in the almost immobile water located in the chalk matrix. Under normal recharge conditions, fissures are inactive and solutes migrate slowly through the chalk matrix. Results also show that concentration dynamics in the saturated zone are related to fluctuations of groundwater levels in the aquifer. A conceptual model is proposed to explain the hydrodispersive behaviour of the variably saturated chalk. Finally, the vulnerability of the chalk to contamination issues occurring at the land surface is discussed. (C) 2003 Elsevier B.V. All rights reserved. [less ▲]

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See detailCarte hydrogéologique de Wallonie, Tavier - Esneux 49/1-2, 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 : mai 2004 (2004)

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See detailCarte hydrogéologique de Wallonie, Natoye - Ciney 54/1-2, 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 : mai 2004 (2004)

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See detailCarte hydrogéologique de Wallonie, Natoye - Ciney 54/1-2
Ruthy, Ingrid ULg; Dassargues, Alain ULg

Cartographic material (2004)

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See detailCarte hydrogéologique de Wallonie, Tavier - Esneux 49/1-2
Ruthy, Ingrid ULg; Dassargues, Alain ULg

Cartographic material (2004)

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See detailClimate change impacts on groundwater resources: modelled deficits in a chalky aquifer, Geer basin, Belgium
Brouyère, Serge ULg; Carabin, Guy; Dassargues, Alain ULg

in Hydrogeology Journal (2004), 12(2), 123-134

An integrated hydrological model (MOHISE) was developed in order to study the impact of climate change on the hydrological cycle in representative water basins in Belgium. This model considers most ... [more ▼]

An integrated hydrological model (MOHISE) was developed in order to study the impact of climate change on the hydrological cycle in representative water basins in Belgium. This model considers most hydrological processes in a physically consistent way, more particularly groundwater flows which are modelled using a spatially distributed, finite-element approach. Thanks to this accurate numerical tool, after detailed calibration and validation, quantitative interpretations can be drawn from the groundwater model results. Considering IPCC climate change scenarios, the integrated approach was applied to evaluate the impact of climate change on the water cycle in the Geer basin in Belgium. The groundwater model is described in detail, and results are discussed in terms of climate change impact on the evolution of groundwater levels and groundwater reserves. From the modelling application on the Geer basin, it appears that, on a pluriannual basis, most tested scenarios predict a decrease in groundwater levels and reserves in relation to variations in climatic conditions. However, for this aquifer, the tested scenarios show no enhancement of the seasonal changes in groundwater levels. [less ▲]

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See detailModélisation des impacts des changements climatiques sur les ressources en eaux souterraines
Dassargues, Alain ULg

Scientific conference (2004, March 17)

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See detailModélisation des impacts des changements climatiques sur les ressources en eaux souterraines
Dassargues, Alain ULg

Scientific conference (2004, March 15)

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