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Zones of certainty and uncertainty in estimating borehole catchments
312A
HYDROGEOLOGY:GROUNDWATER
approaches in optimizing the network for the above mentioned area. Universal kriging was then used to map the minimum error variance estimates for each of these three approaches. General relative variogram appeared to give the best results. (Authors)
957071 Three-dimeusionul modelling of flow and reactive transport in heterogeneous porous media M. A. Cushey, A. Bcllin & Y. Rubin, in: Groundwater
quality: remediation and protection. Proc. conference, Prague, 1995, ed K. Kovar & J. Krasny, (IAHS; Publication, 225), 1995, pp 257-261.
957068 Zones of certainty and uncertainty in estimating borehole catchments S. Evers & D. N. Lerner, in: Groundwater quality: remediation and protection. Proc. conference, Prague, 1995, ed K. Kovar & J. Krasny, (IAHS; Publication, 225), 1995, pp 483491. Protection zones for boreholes are defined through the use of pathline tracing in groundwater flow models. Traditional approaches to groundwater flow modelling focus on obtaining a single best model. This paper outlines a procedure to determine the range of predictions of catchments which would arise from alternative calibrations of a model. The range of catchments is used to identify zones of certainty and uncertainty, leading to alternative definitions of the protection zone for differing purposes. An example is presented, based on Bestwood Pumping Station, Nottinghamshire, UK. (from Authors)
A method is described for simulating three-dimensional (31)) flow fields for use in transport modelling of contaminant migration in statistically anisotropic heterogeneous aquifers. This method differs from previous approaches in that the flow field is generated directly, reducing the computational requirements considerably by bypassing the interim steps of the more traditional techniques. The approach discussed here provides a more computationally efficient and verifiable means of modelling transport in a 3D formation. The method will enable the generation of concentration and travel time probability distribution functions (PDFs) as well as 3D images of the contaminant plume. (Authors) 957072 Using simulation procedures to characterize natural heterogeneous porous media for flow and contaminant transport C. Alimonti & U. Bilardo, in: Groundwater quality:
remediation and protection. Proc. conference, Prague, 1995, ed K. Kovar & J. Krasny, (IAHS; Publication, 225), 1995, pp 185-192.
957069 Identification of zones of higher aquifer vulnerability by means of stable environmental isotopes F. Lopez-Vera, J. Silar, E. Fabian, R. Redondo & C. Gomez Artola, in: Groundwater quality: remediation and protection. Proc. conference, Prague, 1995, ed K. Kovar & J. Krasny, (IAHS; Publication, 225), 1995, pp 21-27. The preferential areas of recharge of aquifers were identified by means of analysis of oxygen- 18 and deuterium. It has been possible to determine that the recharge of the aquifers does not occur in a uniform way within the whole surface of the watersheds but originates in preferential (local) zones. These zones are the heads of streams in the watersheds and the stream beds and outcrops of aquifers at the margin between the aquifer and a mountainous massif to the northwest. Such recharge zones of aquifers form the most vulnerable areas which need to be protected from various sources of contamination. (from Authors)
Many studies, devoted to measurement of hydraulic conductivity, have concluded that in most cases geological formations are heterogeneous. In order to generate a twodimensional hydraulic conductivity field, in respect of its spatial distribution, different geostatistical simulation techniques can be used. To introduce the simulated data for hydraulic conductivity into the flow simulator, if required, it is necessary to make a normalization of values. The main effect of the normalization procedure in averaging petrophysical properties is the enhancement of the lowest values, but there is also a generation of anisotropy relating to the geological structure. The main result in this study shows that the use of geostatistieal techniques seems to be a good way to optimize the calibration step of an aquifer model. (Authors) 957073 Transport of solutes in fractured media, based on a channel network model B. Gylling, L. Moreno & I. Neretnieks, in: Groundwater
quality: remediation and protection, proc. conference, Prague, 1995, ed K. Kovar & J. Krasny, (IAHS; Publication, 225), 1995, pp 107-113. 957070 Modelling multiple solute transport in variably saturated soils J. Simunek, M. T. Van Genuchten & D. L. Suarez, in:
Groundwater quality: remediation and protection. Proc. conference, Prague, 1995, ed K. Kovar & J. Krasny, (IAHS; Publication, 225), 1995, pp 311-318. This paper presents two models typical of two different approaches used for modelling the advective-dispersive transport of multiple ions in variably-saturated porous media. The first approach assumes that all solute reactions can be incorporated directly into the governing transport equations (the one-step method), while the second approach divides the mathematical solution process into two separate steps: one for transport, and one for most or all chemical reactions (the two-step method). The two approaches are illustrated using the one-step CHAIN-2D code which simulates the nonlinear nonequilibrium transport of solutes involved in sequential first-order decay reactions, and the two-step UNSATCHEM2I) code which considers equilibrium and kinetic nonequilibrium chemistry of major ions. (Authors)
Fluid flow and solute transport in fractured media take place mainly through preferential paths in the fractures. Solutes are transported through these paths or channels and they may diffuse into the stagnant water in the porous matrix. A new type of model concept for describing flow and transport in fractured reck has been devised which specifically emphasizes the matrix interaction. The flowing water in the reck is envisaged to take place in a three-dimensional network of channels with stochastic properties. The important transport parameters are summarized and how they may be obtained in the field is described. A long term pumping test with tracers at the Swedish Aspo reck laboratory was predicted reasonably well using this model. (from Authors) 957074 Transport of gas-phase contaminants through structured unsaturated porous media J. Popovicova & M. L. Brusseau, in: Groundwater quality:
remediation and protection. Proc. conference, Prague, 1995, ed K. Kovar & J. Krasny, (IAHS; Publication, 225), 1995, pp 133-138.
HYDROGEOLOGY:GROUNDWATER
approaches in optimizing the network for the above mentioned area. Universal kriging was then used to map the minimum error variance estimates for each of these three approaches. General relative variogram appeared to give the best results. (Authors)
957071 Three-dimeusionul modelling of flow and reactive transport in heterogeneous porous media M. A. Cushey, A. Bcllin & Y. Rubin, in: Groundwater
quality: remediation and protection. Proc. conference, Prague, 1995, ed K. Kovar & J. Krasny, (IAHS; Publication, 225), 1995, pp 257-261.
957068 Zones of certainty and uncertainty in estimating borehole catchments S. Evers & D. N. Lerner, in: Groundwater quality: remediation and protection. Proc. conference, Prague, 1995, ed K. Kovar & J. Krasny, (IAHS; Publication, 225), 1995, pp 483491. Protection zones for boreholes are defined through the use of pathline tracing in groundwater flow models. Traditional approaches to groundwater flow modelling focus on obtaining a single best model. This paper outlines a procedure to determine the range of predictions of catchments which would arise from alternative calibrations of a model. The range of catchments is used to identify zones of certainty and uncertainty, leading to alternative definitions of the protection zone for differing purposes. An example is presented, based on Bestwood Pumping Station, Nottinghamshire, UK. (from Authors)
A method is described for simulating three-dimensional (31)) flow fields for use in transport modelling of contaminant migration in statistically anisotropic heterogeneous aquifers. This method differs from previous approaches in that the flow field is generated directly, reducing the computational requirements considerably by bypassing the interim steps of the more traditional techniques. The approach discussed here provides a more computationally efficient and verifiable means of modelling transport in a 3D formation. The method will enable the generation of concentration and travel time probability distribution functions (PDFs) as well as 3D images of the contaminant plume. (Authors) 957072 Using simulation procedures to characterize natural heterogeneous porous media for flow and contaminant transport C. Alimonti & U. Bilardo, in: Groundwater quality:
remediation and protection. Proc. conference, Prague, 1995, ed K. Kovar & J. Krasny, (IAHS; Publication, 225), 1995, pp 185-192.
957069 Identification of zones of higher aquifer vulnerability by means of stable environmental isotopes F. Lopez-Vera, J. Silar, E. Fabian, R. Redondo & C. Gomez Artola, in: Groundwater quality: remediation and protection. Proc. conference, Prague, 1995, ed K. Kovar & J. Krasny, (IAHS; Publication, 225), 1995, pp 21-27. The preferential areas of recharge of aquifers were identified by means of analysis of oxygen- 18 and deuterium. It has been possible to determine that the recharge of the aquifers does not occur in a uniform way within the whole surface of the watersheds but originates in preferential (local) zones. These zones are the heads of streams in the watersheds and the stream beds and outcrops of aquifers at the margin between the aquifer and a mountainous massif to the northwest. Such recharge zones of aquifers form the most vulnerable areas which need to be protected from various sources of contamination. (from Authors)
Many studies, devoted to measurement of hydraulic conductivity, have concluded that in most cases geological formations are heterogeneous. In order to generate a twodimensional hydraulic conductivity field, in respect of its spatial distribution, different geostatistical simulation techniques can be used. To introduce the simulated data for hydraulic conductivity into the flow simulator, if required, it is necessary to make a normalization of values. The main effect of the normalization procedure in averaging petrophysical properties is the enhancement of the lowest values, but there is also a generation of anisotropy relating to the geological structure. The main result in this study shows that the use of geostatistieal techniques seems to be a good way to optimize the calibration step of an aquifer model. (Authors) 957073 Transport of solutes in fractured media, based on a channel network model B. Gylling, L. Moreno & I. Neretnieks, in: Groundwater
quality: remediation and protection, proc. conference, Prague, 1995, ed K. Kovar & J. Krasny, (IAHS; Publication, 225), 1995, pp 107-113. 957070 Modelling multiple solute transport in variably saturated soils J. Simunek, M. T. Van Genuchten & D. L. Suarez, in:
Groundwater quality: remediation and protection. Proc. conference, Prague, 1995, ed K. Kovar & J. Krasny, (IAHS; Publication, 225), 1995, pp 311-318. This paper presents two models typical of two different approaches used for modelling the advective-dispersive transport of multiple ions in variably-saturated porous media. The first approach assumes that all solute reactions can be incorporated directly into the governing transport equations (the one-step method), while the second approach divides the mathematical solution process into two separate steps: one for transport, and one for most or all chemical reactions (the two-step method). The two approaches are illustrated using the one-step CHAIN-2D code which simulates the nonlinear nonequilibrium transport of solutes involved in sequential first-order decay reactions, and the two-step UNSATCHEM2I) code which considers equilibrium and kinetic nonequilibrium chemistry of major ions. (Authors)
Fluid flow and solute transport in fractured media take place mainly through preferential paths in the fractures. Solutes are transported through these paths or channels and they may diffuse into the stagnant water in the porous matrix. A new type of model concept for describing flow and transport in fractured reck has been devised which specifically emphasizes the matrix interaction. The flowing water in the reck is envisaged to take place in a three-dimensional network of channels with stochastic properties. The important transport parameters are summarized and how they may be obtained in the field is described. A long term pumping test with tracers at the Swedish Aspo reck laboratory was predicted reasonably well using this model. (from Authors) 957074 Transport of gas-phase contaminants through structured unsaturated porous media J. Popovicova & M. L. Brusseau, in: Groundwater quality:
remediation and protection. Proc. conference, Prague, 1995, ed K. Kovar & J. Krasny, (IAHS; Publication, 225), 1995, pp 133-138.