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Fluid flow and solute transfort in a network of channels
130A
HYDROGEOLOGY:GROUNDWATER
the properties of the skin are measured using type-curve analysis. Conservely, the type curves for the case where the skin zone is of greater permeability than the formation show a unique and interpretable shape for each skin thickness and ratio of formatlon to skin permeability over most practical values of hydraulic diffusivity. -from Author 943057 Fluid flow and solute transport in a network of channels L. Moreno & I. Neretnieks, Journal of Contaminant Hydrology, 14(3-4), 1993, pp 163-192. A new model to describe flow and transport in fractured rocks is proposed. It is based on the concept of a network of channels. The individual channel members are given stochastically selected conductances and volumes. For large standard deviations in conductances, channeling becomes pronounced with most of the water flowing in a few paths. The effluent patterns and flow-rate distributions obtained in the simulations have been compared to three field measurements in drifts and tunnels of flow-rate distributions. A particle-following technique was used to simulate solute transport in the network. -from Authors 943058 Field measurement of radial solute transport in fractured rock K. S. Novakowski & P. A. Lapcevic, Water Resources Research, 30(1), 1994, pp 37-44. The results of a tracer experiment conducted in a single fracture are interpreted using a semianalytical model which accounts for advective dispersion, matrix diffusion, mixing in the test zones, and for tortuosity. The experiment was conducted using a conservative tracer which was injected into a steady divergent flow field. Arrival of ~acer was monitored in an array of 13 boreholes intersecting the fracture over a square area of approximately 30 m on a side. The individual advective processes that contribute to advective dispersion remain unresolved on the basis of this experiment. -from Authors 943059
Analysis of flow in an observation well inter-
secting a single fracture P. A.
Lapcevic, K. S. Novakowski & F. L. Paillet,
Journal of Hydrology, 151(2-4), 1993, pp 229-239. A semi-analytical model is developed to determine transmissivity and storativity from the interpretation of transient flow in an observation well due to pumping in a source well where the two wells are connected by a single fracture. Flow rate can be determined using a beat-pulse flowmeter located above the intersection of the fracture in the observation well. The results of a field experiment were interpreted using the new model and compared with drawdown data from the same test. Good agreement between the transmissivity estimates was observed whereas estimates of storativity were found to be better determined from the analysis of flow rate. -Authors 943060 A simple and convenient test for determining transmissibility of an aquifer in a well (in Chinese) Zhang Zhaodong, Wang Xueju & Feng Zhaieheng, Seismology & Geology, 15(3), 1993, pp 207-212. A new test method for determining transmissibility of an a~uifer in a well is described. Using a test of step change o t air pressure at well head, the transmissibihty of an .aquifer]n Liaocheng city is determined to be 14.4m2/d. But it was determined by pumping test to be 43.6m2/d. Both the data have the same order of magnitude. This test is more simple and convenient, more economical and faster than the pumping test. It is also more reasonable to explain the micro-regime of groundwater and easier to be used in practice. -English summary 943061 Considerazioni su piezometri a ' c a n n a aperta', acquiferi multistrato e prove di pompaggio in regime di eq.uilibrio e di pseudo-equilibrio (Remarks about open p~ezometers, multilayer aquifers and pumpmg tests in both steady and pseudo-steady state) P. Angelini & W. Dragoni, Geologia Applicata e Idrogeologia, 26, 1991, pp 71-84. Some equations are proposed for dealing with the data obtained from a pumping test carried out, in a steady state or pseudo-steady state, in a well passing through two
aquifers having different initial potentials. These equations permit the calculation and definition of the steady state potential in the well before pumping; the transmissivity of the separate aquifers; the 'equtvalent' transmissivity T which is obtained by applying the Thiem-Dupuit equation~ and the influence radii of the separate aquifers. This note shows that in pumping tests it is necessary to measure the levels in the well and in piezometers against a single, constant reference plane a n d n o t , as is often done, against the level of the top of the well shaft. -from English summary 943062 Etude par modele mathematique du comportement hydrodynamique d ' u n e napj~e alluviale en presence d ' u n e . g r a v i e r e : cas de la plame alluviale de l ' O r b (Study using a mathematical model of the hydrodynamic behaviour of an alluvial aquifer in the presence of a gravel q u a r r y : the Orb alluvial plain) L.M. Bangoy, Hydrogeologie, 3, 1993, pp 187-198. The presence of gravel-pits in aUuvial aquifers causes two significant hydrodynamxc effects: piezometric disturbances around the gravel-pit and disturbances in water exchange between the aquifer and the surface water. The present study quantifies both of these effects. The different shapes and dimensions of the gravel-pits and their position with respect to the local groundwater flow direction were simulated for steady-state flow conditions. -from English summary 943063 Significance of vertical flow through low-conductivity zones in Bromsgrove Sandstone Aquifer K. R. Rushton & S. Salmon, Journal of Hydrology, 152(1-4), 1993, pp 131-152. When water passes vertically through low-conductivity zones in aquifers, significant vertical head gradients occur. The importance of such gradients is identified in a study of the Bromsgrove Sandstone Aquifer Unit. A mathematical model incorporating the low-conductivity layers has been developed to explain the changed conditions from 1900, when there were extensive spring flows, to the present day, when deep boreholes intercept much of the groundwater flow. The mathematical model also helps in understanding the changing pumped drawdowns and water table elevations. -Authors 943064 Two-phase flow in smooth and rough fractures: measurement and correlation by porous-medium and pipe flow models M. Fourar, S. Bories, R. Lenormand & P. Persoff, Water Resources Research, 29(11), 1993, pp 3699-3708. Two-phase (air-water) flow experiments were conducted in horizontal artificial fractures. The fractures were between glass plates that were either smooth or artificially roughened by gluing a layer of glass beads to them. One smooth fracture and three rough fractures were studied. For both types of fractures, the flow structures are similar to those observed in two-phase flow in a pipe, with structures depending on the gas and liquid flow rates. The pressure gradients measured for different liquid and gas velocities were interpreted by three models. Fxrst, using Darcy's law. Second, the standard approach for two-phase flow in pipes (Lockhart and Martinelli's equation) agrees with experimental results. Finally, the best fit was obtained by treating the two phases as one homogeneous phase. -from Authors 943065 Flow characterization through heat transfer evidence in a carbonate fractured medium: first approach Y. Benderitter, B. Roy & A. Tabbagh, Water Resources Research, 29(11), 1993, pp 3741-3747. Water temperature records at the outlet of a fractured carbon.ate system during an annual cycle show two types of variation, slow variations over a small range, resulting from the thermal equilibrium between water and rock in the aquifer, and more rapid variations over a wider range, transmitted more quickly due to the inflow of water through fractures or karstic pipes. Starting at the outlet first a model of thermal exchange for flow in a conduit, then a model of thermal exchange in a porous medium between the surface and the reservoir are presented. The comparison with the data recorded at Gulchy (Nievre, France)
HYDROGEOLOGY:GROUNDWATER
the properties of the skin are measured using type-curve analysis. Conservely, the type curves for the case where the skin zone is of greater permeability than the formation show a unique and interpretable shape for each skin thickness and ratio of formatlon to skin permeability over most practical values of hydraulic diffusivity. -from Author 943057 Fluid flow and solute transport in a network of channels L. Moreno & I. Neretnieks, Journal of Contaminant Hydrology, 14(3-4), 1993, pp 163-192. A new model to describe flow and transport in fractured rocks is proposed. It is based on the concept of a network of channels. The individual channel members are given stochastically selected conductances and volumes. For large standard deviations in conductances, channeling becomes pronounced with most of the water flowing in a few paths. The effluent patterns and flow-rate distributions obtained in the simulations have been compared to three field measurements in drifts and tunnels of flow-rate distributions. A particle-following technique was used to simulate solute transport in the network. -from Authors 943058 Field measurement of radial solute transport in fractured rock K. S. Novakowski & P. A. Lapcevic, Water Resources Research, 30(1), 1994, pp 37-44. The results of a tracer experiment conducted in a single fracture are interpreted using a semianalytical model which accounts for advective dispersion, matrix diffusion, mixing in the test zones, and for tortuosity. The experiment was conducted using a conservative tracer which was injected into a steady divergent flow field. Arrival of ~acer was monitored in an array of 13 boreholes intersecting the fracture over a square area of approximately 30 m on a side. The individual advective processes that contribute to advective dispersion remain unresolved on the basis of this experiment. -from Authors 943059
Analysis of flow in an observation well inter-
secting a single fracture P. A.
Lapcevic, K. S. Novakowski & F. L. Paillet,
Journal of Hydrology, 151(2-4), 1993, pp 229-239. A semi-analytical model is developed to determine transmissivity and storativity from the interpretation of transient flow in an observation well due to pumping in a source well where the two wells are connected by a single fracture. Flow rate can be determined using a beat-pulse flowmeter located above the intersection of the fracture in the observation well. The results of a field experiment were interpreted using the new model and compared with drawdown data from the same test. Good agreement between the transmissivity estimates was observed whereas estimates of storativity were found to be better determined from the analysis of flow rate. -Authors 943060 A simple and convenient test for determining transmissibility of an aquifer in a well (in Chinese) Zhang Zhaodong, Wang Xueju & Feng Zhaieheng, Seismology & Geology, 15(3), 1993, pp 207-212. A new test method for determining transmissibility of an a~uifer in a well is described. Using a test of step change o t air pressure at well head, the transmissibihty of an .aquifer]n Liaocheng city is determined to be 14.4m2/d. But it was determined by pumping test to be 43.6m2/d. Both the data have the same order of magnitude. This test is more simple and convenient, more economical and faster than the pumping test. It is also more reasonable to explain the micro-regime of groundwater and easier to be used in practice. -English summary 943061 Considerazioni su piezometri a ' c a n n a aperta', acquiferi multistrato e prove di pompaggio in regime di eq.uilibrio e di pseudo-equilibrio (Remarks about open p~ezometers, multilayer aquifers and pumpmg tests in both steady and pseudo-steady state) P. Angelini & W. Dragoni, Geologia Applicata e Idrogeologia, 26, 1991, pp 71-84. Some equations are proposed for dealing with the data obtained from a pumping test carried out, in a steady state or pseudo-steady state, in a well passing through two
aquifers having different initial potentials. These equations permit the calculation and definition of the steady state potential in the well before pumping; the transmissivity of the separate aquifers; the 'equtvalent' transmissivity T which is obtained by applying the Thiem-Dupuit equation~ and the influence radii of the separate aquifers. This note shows that in pumping tests it is necessary to measure the levels in the well and in piezometers against a single, constant reference plane a n d n o t , as is often done, against the level of the top of the well shaft. -from English summary 943062 Etude par modele mathematique du comportement hydrodynamique d ' u n e napj~e alluviale en presence d ' u n e . g r a v i e r e : cas de la plame alluviale de l ' O r b (Study using a mathematical model of the hydrodynamic behaviour of an alluvial aquifer in the presence of a gravel q u a r r y : the Orb alluvial plain) L.M. Bangoy, Hydrogeologie, 3, 1993, pp 187-198. The presence of gravel-pits in aUuvial aquifers causes two significant hydrodynamxc effects: piezometric disturbances around the gravel-pit and disturbances in water exchange between the aquifer and the surface water. The present study quantifies both of these effects. The different shapes and dimensions of the gravel-pits and their position with respect to the local groundwater flow direction were simulated for steady-state flow conditions. -from English summary 943063 Significance of vertical flow through low-conductivity zones in Bromsgrove Sandstone Aquifer K. R. Rushton & S. Salmon, Journal of Hydrology, 152(1-4), 1993, pp 131-152. When water passes vertically through low-conductivity zones in aquifers, significant vertical head gradients occur. The importance of such gradients is identified in a study of the Bromsgrove Sandstone Aquifer Unit. A mathematical model incorporating the low-conductivity layers has been developed to explain the changed conditions from 1900, when there were extensive spring flows, to the present day, when deep boreholes intercept much of the groundwater flow. The mathematical model also helps in understanding the changing pumped drawdowns and water table elevations. -Authors 943064 Two-phase flow in smooth and rough fractures: measurement and correlation by porous-medium and pipe flow models M. Fourar, S. Bories, R. Lenormand & P. Persoff, Water Resources Research, 29(11), 1993, pp 3699-3708. Two-phase (air-water) flow experiments were conducted in horizontal artificial fractures. The fractures were between glass plates that were either smooth or artificially roughened by gluing a layer of glass beads to them. One smooth fracture and three rough fractures were studied. For both types of fractures, the flow structures are similar to those observed in two-phase flow in a pipe, with structures depending on the gas and liquid flow rates. The pressure gradients measured for different liquid and gas velocities were interpreted by three models. Fxrst, using Darcy's law. Second, the standard approach for two-phase flow in pipes (Lockhart and Martinelli's equation) agrees with experimental results. Finally, the best fit was obtained by treating the two phases as one homogeneous phase. -from Authors 943065 Flow characterization through heat transfer evidence in a carbonate fractured medium: first approach Y. Benderitter, B. Roy & A. Tabbagh, Water Resources Research, 29(11), 1993, pp 3741-3747. Water temperature records at the outlet of a fractured carbon.ate system during an annual cycle show two types of variation, slow variations over a small range, resulting from the thermal equilibrium between water and rock in the aquifer, and more rapid variations over a wider range, transmitted more quickly due to the inflow of water through fractures or karstic pipes. Starting at the outlet first a model of thermal exchange for flow in a conduit, then a model of thermal exchange in a porous medium between the surface and the reservoir are presented. The comparison with the data recorded at Gulchy (Nievre, France)