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Devonian carbonate aquifer to the Mad River Valley, southwestern Ohio
366A
HYDROGEOLOGY:GROUNDWATER
TOUGH2. The model is used to solve two classic coupled flow problems as verification. The model is then applied to a salt dome flow problem patterned after the conditions present at the Gorleben salt dome, Germany, a potential site for highlevel nuclear waste disposal. (from Authors)
958O67 Validation of a f'mite element code to simulate the coupled problem of salt transport in groundwater A. Dassargucs, in: Computer techniques in environmental studies V. Vol. I: pollution modeling, ed P. Zannetti, (Computational Mechanics Publications), 1994, pp 173-180. Groundwater contaminations by salt water are frequently observed especially in coastal zones. Moreover, upconing phenomena induced by important pumping is one of the major factor stressing and aggravating the process. A finite element program able to simulate accurately this kind of problems is proposed: the SUFT program (Saturated Unsaturated Flow and Transport model). In order to avoid numerical instabilities, two methods have been introduced in this code covering by this way all the practical cases: the convection dominated as well as the dispersion/diffusion dominated transport cases. (from Author)
958068 Using genetic algorithms to solve a multiobjeetive groundwater monitoring problem S. E. Cieniawski, J. W. Eheart & S. Ranjithan, Water Resources Research, 31(2), 1995, pp 399-409. This paper builds on the work of Meyer and Brill (1988) and subsequent work by Meyer ctal. (1990, 1992) on the optimal location of a network of groundwater monitoring wells under conditions of uncertainty. A method of optimization using genetic algorithm~ (GAs) is investigated which allows us to consider the two objectives of Meyer et al. (1992), maximizing reliability and minimizing contaminated area at the time of first detection, separately yet simultaneously. Four different codings of genetic algorithms are investigated, and their performance in generating the multiobjective trade-off curve is evaluated for the groundwater monitoring problem using an example data set. (from Authors)
958069 Design of groundwater monitoring networks for landfills P. D. Meyer, J. W. Eheart, S. Ranjithan & A. J. Valocehi, in: New uncertainty concepts in hydrology and water resources, ed Z.W. Kundzewicz, (Cambridge University Press), 1995, pp 190-196. Designing a system to monitor groundwater for contamination from landfills involves a tradenff between cost, time of detection, and probability of detection. As monitoring wells are spaced more closely together, the probability of detecting a leak improves. Locating monitoring wells further downgradient of the landfill also improves detection probability because the plume disperses more and is less likely to move undetected between two monitoring wells. However, closer spacing costs more, and location further away from the source implies a greater time of detection and a greater probability that a water supply well will become contaminated. A method is discussed for designing a monitoring system under parameter uncertainty. This method places a given number of wells in locations that maximize the probability of detection of a plume. The method requires some prior knowledge of the statisticalproperties of the conductivity parameters of the aquifer and some knowledge of the probability of leak occurring at any given point in the landfill.The method is microcomputer based. (from Authors)
958070 Ground-water contribution from the Silurian/Devonian carbonate aquifer to the Mad River Valley, southwestern Ohio R. A. Sheets & W. P. Yost, Ohio Journal of Science, 94(5), 1994, pp 138-146. The US Geological Survey Regional Aqnifer-System Analysis is examining the Silurian and Devonian carbonate aquifer and overlying glacial deposits of western Ohio and eastern Indiana in terms of the hydrogeologie framework, groundwater-flow system and water chemistry, and response to withdrawals and development. This paper describes the hydrogeology of an area in southwestern Ohio that contains the Mad River Valley, an outwash valley that is incised through the relatively permeable Silurian bedrock into the relatively impermeable Ordovician bedrock at the southern boundary. Ground-water-flow patterns based on a synoptic water-level survey of 80 bedrock wells in the aquifer indicate that flow is toward the valley. A ground-water basin was delineated from the potentiometric-surface map and used in conjunction with a low-flow gain-loss study to derive a generalized ground-water/surface-water budget for the area. (from Authors)
958071 A proposed geological parameterization method for parameter identification in three-dimensional groundwater modeling Ne-Zheng Sun, Ming-Chin Jeng & W. W.-G. Yeh, Water Resources Research, 31(1), 1995, pp 89-102. A new parameterization method for parameter identification is presented. This method allows us to incorporate all well log data and any other geological information into the inverse solution procedure for three-dimensional groundwater modeling. In the proposed method, unknown parameters, such as hydraulic conductivity and storage coefficient, are directly related to the geological materials. Existing well logs of an aquifer can provide information of local geological structures along the vertical direction. By us/ng these data, as well as any other geological information available, the three-dimensional structure of the aquifer can be estimated by means of the geostatistical method. Then, an inverse problem can be formulated, leaving fewer unknown parameters to be identified. The proposed methodology has enabled the threedimensional distribution of hydraulic conductivity and storativity in the Hemct basin, Riverside, California, to be determined. (from Authors)
958072 Safe yield of aquifers J. C. Miles & P. D. Chambet, Journal of Water Resources Planning & Management - ASCE, 121(1), 1995, pp 1-8. Existing methods for determining the perennial safe yield of ground-water basins are examined. The inherent problems of these methods are described. A new method of estimating the safe yield is developed, which includes approximate representations of basin dimensions, hydraulic characteristics, and estimated duration of the worst drought. The suitability of the method for application to real aquifers is tested using a distributed parameter surface water/ground-water model of an aquifer in the English Midlands. For this particular example the method is shown to work well. (from Authors)
958073 Chalk fracture system characteristics: implications for flow and solute transport P. L. Younger & T. Elliot, Quarterly Journal of Engineering Geology, 28(Suppl.), 1995, pp $39-$50. Bulk groundwater flow and solute advection occur in the fractures of the UK Chalk, and a knowledge of the frequency and aperture of these fractures is crucial to understanding
HYDROGEOLOGY:GROUNDWATER
TOUGH2. The model is used to solve two classic coupled flow problems as verification. The model is then applied to a salt dome flow problem patterned after the conditions present at the Gorleben salt dome, Germany, a potential site for highlevel nuclear waste disposal. (from Authors)
958O67 Validation of a f'mite element code to simulate the coupled problem of salt transport in groundwater A. Dassargucs, in: Computer techniques in environmental studies V. Vol. I: pollution modeling, ed P. Zannetti, (Computational Mechanics Publications), 1994, pp 173-180. Groundwater contaminations by salt water are frequently observed especially in coastal zones. Moreover, upconing phenomena induced by important pumping is one of the major factor stressing and aggravating the process. A finite element program able to simulate accurately this kind of problems is proposed: the SUFT program (Saturated Unsaturated Flow and Transport model). In order to avoid numerical instabilities, two methods have been introduced in this code covering by this way all the practical cases: the convection dominated as well as the dispersion/diffusion dominated transport cases. (from Author)
958068 Using genetic algorithms to solve a multiobjeetive groundwater monitoring problem S. E. Cieniawski, J. W. Eheart & S. Ranjithan, Water Resources Research, 31(2), 1995, pp 399-409. This paper builds on the work of Meyer and Brill (1988) and subsequent work by Meyer ctal. (1990, 1992) on the optimal location of a network of groundwater monitoring wells under conditions of uncertainty. A method of optimization using genetic algorithm~ (GAs) is investigated which allows us to consider the two objectives of Meyer et al. (1992), maximizing reliability and minimizing contaminated area at the time of first detection, separately yet simultaneously. Four different codings of genetic algorithms are investigated, and their performance in generating the multiobjective trade-off curve is evaluated for the groundwater monitoring problem using an example data set. (from Authors)
958069 Design of groundwater monitoring networks for landfills P. D. Meyer, J. W. Eheart, S. Ranjithan & A. J. Valocehi, in: New uncertainty concepts in hydrology and water resources, ed Z.W. Kundzewicz, (Cambridge University Press), 1995, pp 190-196. Designing a system to monitor groundwater for contamination from landfills involves a tradenff between cost, time of detection, and probability of detection. As monitoring wells are spaced more closely together, the probability of detecting a leak improves. Locating monitoring wells further downgradient of the landfill also improves detection probability because the plume disperses more and is less likely to move undetected between two monitoring wells. However, closer spacing costs more, and location further away from the source implies a greater time of detection and a greater probability that a water supply well will become contaminated. A method is discussed for designing a monitoring system under parameter uncertainty. This method places a given number of wells in locations that maximize the probability of detection of a plume. The method requires some prior knowledge of the statisticalproperties of the conductivity parameters of the aquifer and some knowledge of the probability of leak occurring at any given point in the landfill.The method is microcomputer based. (from Authors)
958070 Ground-water contribution from the Silurian/Devonian carbonate aquifer to the Mad River Valley, southwestern Ohio R. A. Sheets & W. P. Yost, Ohio Journal of Science, 94(5), 1994, pp 138-146. The US Geological Survey Regional Aqnifer-System Analysis is examining the Silurian and Devonian carbonate aquifer and overlying glacial deposits of western Ohio and eastern Indiana in terms of the hydrogeologie framework, groundwater-flow system and water chemistry, and response to withdrawals and development. This paper describes the hydrogeology of an area in southwestern Ohio that contains the Mad River Valley, an outwash valley that is incised through the relatively permeable Silurian bedrock into the relatively impermeable Ordovician bedrock at the southern boundary. Ground-water-flow patterns based on a synoptic water-level survey of 80 bedrock wells in the aquifer indicate that flow is toward the valley. A ground-water basin was delineated from the potentiometric-surface map and used in conjunction with a low-flow gain-loss study to derive a generalized ground-water/surface-water budget for the area. (from Authors)
958071 A proposed geological parameterization method for parameter identification in three-dimensional groundwater modeling Ne-Zheng Sun, Ming-Chin Jeng & W. W.-G. Yeh, Water Resources Research, 31(1), 1995, pp 89-102. A new parameterization method for parameter identification is presented. This method allows us to incorporate all well log data and any other geological information into the inverse solution procedure for three-dimensional groundwater modeling. In the proposed method, unknown parameters, such as hydraulic conductivity and storage coefficient, are directly related to the geological materials. Existing well logs of an aquifer can provide information of local geological structures along the vertical direction. By us/ng these data, as well as any other geological information available, the three-dimensional structure of the aquifer can be estimated by means of the geostatistical method. Then, an inverse problem can be formulated, leaving fewer unknown parameters to be identified. The proposed methodology has enabled the threedimensional distribution of hydraulic conductivity and storativity in the Hemct basin, Riverside, California, to be determined. (from Authors)
958072 Safe yield of aquifers J. C. Miles & P. D. Chambet, Journal of Water Resources Planning & Management - ASCE, 121(1), 1995, pp 1-8. Existing methods for determining the perennial safe yield of ground-water basins are examined. The inherent problems of these methods are described. A new method of estimating the safe yield is developed, which includes approximate representations of basin dimensions, hydraulic characteristics, and estimated duration of the worst drought. The suitability of the method for application to real aquifers is tested using a distributed parameter surface water/ground-water model of an aquifer in the English Midlands. For this particular example the method is shown to work well. (from Authors)
958073 Chalk fracture system characteristics: implications for flow and solute transport P. L. Younger & T. Elliot, Quarterly Journal of Engineering Geology, 28(Suppl.), 1995, pp $39-$50. Bulk groundwater flow and solute advection occur in the fractures of the UK Chalk, and a knowledge of the frequency and aperture of these fractures is crucial to understanding