ISSN:0017-467X    

DOI:10.1111/j.1745-6584.1988.tb00406.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

ABSTRACTComposite aquifers composed of relatively high storage, low permeability regolith overlying low storage, higher permeability fissured bedrock occur in the Basement terrain of Victoria Province. The adequacy of these aquifers for rural‐water supplies is variable and locating optimum borehole sites is difficult. The analysis of data from the Victoria Province Drought Relief Project suggests that a variety of environmental factors influence borehole yield. Despite the wide scatter of data, certain generalizations can be made using statistical techniques. The results show that for regolith aquifers specific capacity increases with rainfall, regolith thickness, and altitude, which is in turn probably related to the age of the erosion surface. In fissured bedrock aquifers the upper 20 m is crucial for the provision of an adequate yiel

ISSN:0017-467X    

DOI:10.1111/j.1745-6584.1988.tb00407.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

ABSTRACTWater levels in piezometers and the hydraulic conductivity of organic and mineral soils were measured during spring and summer 1986 to evaluate the recharge‐discharge function of wetlands in the vicinity of the Mendenhall Valley near Juneau, Alaska. Computer modeling experiments were also done to evaluate the function of a large patterned fen.The blanket bogs are probably recharge zones, whereas forested wetlands are discharge zones. Approximately the upper third of the patterned fen is a ground‐water recharge zone, whereas its northern margin receives ground‐water discharge from flow systems recharged on moraines.The amounts of wetland recharge and discharge are very small. Recharge from wetlands to viable aquifers is probably less than 1% of the total annual recharge to the aquifer system. The amount of ground‐water discharge to streams from wetlands is too small to

ISSN:0017-467X    

DOI:10.1111/j.1745-6584.1988.tb00408.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

ABSTRACTDevelopment of a numerical algorithm to analyze slug test data is described. This type of test is very popular for aquifer testing, primarily because of its simplicity. Many such tests are performed to estimate the hydraulic conductivity values of ground‐water‐bearing formations. Those values in turn are used to calculate pore‐water velocities. The algorithm was coded and successfully tested for a hypothetical data set. It has also been applied at a number of field locations. One such application is pres

ISSN:0017-467X    

DOI:10.1111/j.1745-6584.1988.tb00409.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

ABSTRACTUsing Zhukovsky's function and Schwarz‐Christoffel conformal mapping technique, unconfined seepage from a river of large width has been analyzed for a steady‐state condition. Seepage quantities occurring through the bed and the bank of the river have been estimated separately. The reach transmissivity constant for a river with large width has been determined. It is found that if the distance between the riverbank and the observation well is more than 0.5 Di, where Di is the saturated thickness of aquifer below the riverbed, the reach transmissivity constant is independent of drawdown at the observation well. The reach transmissivity constant depends on the depth of water in the river and the distance of the observation well from the riverb

ISSN:0017-467X    

DOI:10.1111/j.1745-6584.1988.tb00410.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

ABSTRACTFluorescent dye tracer technology now permits accurate determination of tracer breakthrough curves in karst hydrology. Such data may be evaluated in terms of hydraulic processes of dispersion, divergence, convergence, dilution, and storage. The breakthrough curve reflects the character of ground‐water flow and the structure of the ground‐water conduit network, so that within constraints of regional geology, geomorphology, and hydrology, it is possible to interpret tracer breakthrough curves to produce a structural model of a karst aquifer. Such structural models provide a basis for further field investigations and rational computer modeling. An example of such an approach is taken from a series of tracer tests on the Castleguard karst aquifer, Alberta, Canada, an alpine karst with rapid conduit flow, and a strongly seasonal flow regime. A dimensionless recovery index is developed to identify the relationship between springs, and this shows that the behavior and configuration of the active aquifer vary dramatically with discha

ISSN:0017-467X    

DOI:10.1111/j.1745-6584.1988.tb00411.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

ABSTRACTThe long‐term ground‐water withdrawal potential of a regional confined aquifer in the Cold Lake area is analyzed with a combined simulation‐optimization model. The Galerkin finite‐element method is used in the simulation model to obtain numerical approximations to the hydraulics of ground‐water flow. This method produces a set of linear algebraic equations containing ground‐water variables which are embedded as equality constraints within the constraint set of a linear programming optimization model. Other constraints in this set include restrictions on drawdown, water demand, and hydraulic gradient. The objective of the optimization model is to maximize total withdrawal from potential ground‐water development sites. The objectives of this modeling study are to assist planners and water managers in formulating a long‐term water management plan on water allocation to industrial users and to establish a long‐term withdrawal limit for the aquifer. Analyses include the determination of users’ground‐water withdrawals to maximize total ground‐water use from the aquifer, the analysis of ground‐water supply tradeoff among water users, and the identification of pumping locations and their pumpages that best intercept ground‐water flow in the aquifer system. Modeling results show that there is an interdependency of optimal ground‐water withdrawals among water users. The maximum total withdrawal obtained from potential ground‐water development sites is 90 percent of total inflow into the aquifer. This withdrawal limit for the aquifer can be increased with a new set of sites chos

ISSN:0017-467X    

DOI:10.1111/j.1745-6584.1988.tb00412.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

ABSTRACTAnisotropy, directional connectivity, and porosity of fracture systems can be estimated from surface azimuthal electrical resistivity surveys. Azimuthal resistivity surveys utilize conventional resistivity equipment and are performed by rotating a Wenner array about a fixed center point and measuring apparent resistivity as a function of azimuth. The depth of investigation is determined by the electrode spacing which is generally limited by practical considerations to approximately 70 m. The azimuthal survey generates an apparent resistivity ellipse from which the properties of a subsurface joint system can be determined. Theoretically the major axis of the resistivity ellipse will coincide with strike of the primary joint set. The ratio of major axis to minor axis of the ellipse defines the coefficient of anisotropy associated with the joints, and from this coefficient, secondary porosity can be calculated.Application of azimuthal surveys at 60 sites in bedrock and clayey till throughout Wisconsin generally yielded joint strikes within a few degrees of direct observations. Porosities calculated for jointed bedrock are within a few percent of values determined by other methods. The absolute values of porosities calculated for the tills appear unreliable due to conduction effects along the surface of clay minerals.Although the theoretical foundation for this technique is based on idealized jointing, the field results indicate that the method is effective in media with multiple joint sets. When mean joint length exceeds the electrode spacing, azimuthal resistivity peaks closely coincide with the mean strikes of observed joint sets. When joint lengths are less than the electrode spacing, the major ellipse axis indicates the most conductive path through the joint system. In both cases, ellipse shape indicates the direction (s) having the greatest joint connectivity, which are also the directions of greatest aquifer permeability.

ISSN:0017-467X    

DOI:10.1111/j.1745-6584.1988.tb00413.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

ABSTRACTA one‐dimensional, finite‐difference model for simulating biodegradation and sorption processes in saturated porous media is developed. The model formulation is general and capable of accommodating a variety of boundary conditions and process theories. Advective and dispersive transport of a substrate and an electron acceptor are considered. Aerobic biodegradation is modeled using a modified Monod function; anaerobic biodegradation is modeled using Michaelis‐Menten kinetics. In addition, first‐order degradation is allowed for both substances. Sorption can be incorporated using linear, Freundlich, or Langmuir equilibrium isotherms for either substance. Dirichlet, Neumann, or Cauchy boundary conditions are allowed, where they are constant in time, or include first‐order degradation. The resulting nonlinear problem is solved using a Newton‐Raphson iterative technique. Model verification is achieved through a series of simulations, two of which arc included. In addition, three applications demonstrate the utility o

ISSN:0017-467X    

DOI:10.1111/j.1745-6584.1988.tb00414.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

ABSTRACTThe USGS MOC Model is a useful tool for evaluating different well patterns in an aquifer restoration scheme under variable hydrogeologic conditions. The best well pattern for a ground‐water cleanup is highly site‐specific and depends upon the objectives and constraints for each problem. In this study, seven different well patterns were investigated to determine the one(s) most efficient in achieving a range of desired levels of contaminant reduction. The well patterns were evaluated on the basis of cleanup time, volume of water circulated, and volume of water requiring treatment. Eight generic hydrogeologic conditions were modeled using different combinations of drawdown, hydraulic gradient, and dispersivity. The key hydrogeologic variables which control the rate of cleanup are well locations, pumping rates, transmissivity, dispersivity, and hydraulic gradient. For a given set of well locations, by varying transmissivity and maintaining drawdown, dispersivity, and hydraulic gradient constant, the cleanup time was found to be inversely related to the pumping r

ISSN:0017-467X    

DOI:10.1111/j.1745-6584.1988.tb00415.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY