ISSN:0017-467X    

DOI:10.1111/j.1745-6584.1981.tb03511.x

出版商:Blackwell Publishing Ltd    

年代:1981

数据来源: WILEY

摘要:

ABSTRACTResponse or “slug” tests to determine the hydraulic conductivity of in situ earth materials are often difficult to perform in situations of very high hydraulic conductivity. In small‐diameter standpipes, rapid response to the induced head difference, often in a matter of seconds, is difficult to measure with conventional well sounders. Instantaneous induction of a known head difference is also a major problem when dealing with very fast response times. A method of performing such tests has been developed, utilizing electronic pressure transducers to monitor the response to a pneumatically induced head. Increased air pressure within the standpipe causes displacement of the water column to accommodate the air pressure. Once the aquifer has re‐equilibrated in this condition, sudden release of the air pressure constitutes an instantaneously induced head difference. The response measured by the electronic pressure transducer can be recorded digitally or by an analog chart recorder with fast paper speed. This method has been used to measure basic time lags in the order of several seconds. The use of electronic pressure transducers and pneumatically induced head differences will allow accurate measurements in situations of higher hydraulic conductivity than would be possible using common response testing tec

ISSN:0017-467X    

DOI:10.1111/j.1745-6584.1981.tb03512.x

出版商:Blackwell Publishing Ltd    

年代:1981

数据来源: WILEY

摘要:

ABSTRACTLarge‐diameter dug wells are the main source of water supply in many areas of the world. They are particularly useful in shallow aquifers with a low transmissivity. Existing methods for determining the transmissivity of aquifers from pumping tests carried out in dug wells were found wanting. This paper describes two new methods that can be used to determine the transmissivity of the aquifer from dug well tests. Examples of the application of the methods are give

ISSN:0017-467X    

DOI:10.1111/j.1745-6584.1981.tb03513.x

出版商:Blackwell Publishing Ltd    

年代:1981

数据来源: WILEY

摘要:

ABSTRACTThe practical application of simulation models of the movement of chemically reacting contaminants requires the evaluation of several chemical parameters in addition to those basic hydrogeologic and hydrodynamic parameters required to model conservative constituents. This paper deals with the use of laboratory‐determined chemical parameter values in the simulation of the transport of ion‐exchanging solutes governed by local chemical equilibrium. The transport model has been applied to a field operation involving the injection of advanced‐treated municipal waste water into an alluvial aquifer in the Palo Alto (California) Baylands region.Basic hydrogeologic parameters, such as porosity, bulk density, and aquifer thickness, were determined by analysis of observation well logs and core samples. Data on the breakthrough of a conservative tracer at various observation wells were utilized to determine an approximate velocity field and the dispersivity values. The chemical parameters (selectivity coefficients and cation‐exchange capacity) were determined using standard batch experiments conducted in the laboratory using aquifer core material. With these parameter values, the model was run to predict the breakthrough of major cations at the observation wells. The predicted results agree very closely with the actual field data. This agreement suggests that laboratory‐determined chemical parameters can be successfully used in field‐scale transport

ISSN:0017-467X    

DOI:10.1111/j.1745-6584.1981.tb03514.x

出版商:Blackwell Publishing Ltd    

年代:1981

数据来源: WILEY

摘要:

ABSTRACTGround‐water flow models developed for the flow systems around Bass Lake and Nepco Lake, Wisconsin, show that models can be useful tools for estimating lake seepage rates. A two‐dimensional profile model for Bass Lake illustrates that the ratio of horizontal to vertical hydraulic conductivity of the aquifer around the lake is related to both the magnitude of vertical hydraulic gradients near the lake and the distribution of seepage from the lake as a function of distance from shore. The model also shows that it is important to know the vertical hydraulic conductivity of littoral lake‐bed sediments to estimate lake seepage rates.A three‐dimensional model constructed for an unusual ground‐water flow system around Nepco Lake provides a more realistic simulation of the flow system than does a comparable two‐dimensional model. Both models were useful for identifying additional data that could be used to quantify the ground‐water portion of the lake's water budget more accurately. It is suggested that a combination of two‐and/or three‐dimensional models could be used to estimate seepage rates at many lakes for which suff

ISSN:0017-467X    

DOI:10.1111/j.1745-6584.1981.tb03515.x

出版商:Blackwell Publishing Ltd    

年代:1981

数据来源: WILEY

摘要:

ABSTRACTRecent emphasis on the need to protect ground‐water quality has resulted in an increased interest in ground‐water quality monitoring, particularly that monitoring performed in support of a regulatory ground‐water quality management program. Such monitoring must involve intensive surveys or special studies, as well as routine trend types of sampling. In both cases, adequate monitoring strategies require careful consideration of the statistical aspects of sampling theory.The purpose of this paper is to present statistical concepts that should be incorporated in the initial planning of a ground‐water quality monitoring program.The means of incorporating statistical theory into ground‐water quality monitoring suggested in this paper involves selecting the number of samples required based on a specified confidence interval about the mean of the variable under consideration. This approach requires that the variance of the sample mean be known. The expression for Var(x̄) will depend on the correlation structure of the population in question. If the observations taken can be assumed independent in both space and time (i.e., no spatial or serial correlation exists), then the number of samples required can be determined in a very straightforward manner. However, if the samples are correlated, part of the information contained in one observation will be contained in other observations as well. As a result, the sample size must be increased in order to achieve the same level of information that would be obtained in uncorrelated observations.Various sampling techniques can be employed in a ground‐water monitoring plan, including simple random sampling, systematic sampling, and stratified random sampling. Each technique has certain advantages and disadvantages with regard to ground‐water monitoring. An overall monitoring program should incorporate the most effective sampling techniques in order to achieve optimum information content from a minimum num

ISSN:0017-467X    

DOI:10.1111/j.1745-6584.1981.tb03516.x

出版商:Blackwell Publishing Ltd    

年代:1981

数据来源: WILEY

摘要:

ABSTRACTA method of researching data at a mine to determine the environmental and economic impact to the operator has been developed. This method consists of developing geologic, hydrologic, and geochemical maps that can be used to provide a three‐dimensional view of the subsurface environment before, during, and after mining.The following maps were developed: a standard topographic base map, structure contour maps, static water level maps, and several iso‐concentration maps for pH, iron, manganese, sulfate, and specific conductance. Where possible geologic‐hydrologic cross sections were drawn to aid in the environmental interpretations. It is possible to use the data to develop the best possible mining plan for a geologic region which considers geographic, technical, economic, and environmental parameters. The iso‐concentration maps for a proposed surface mine site can be used to define the extent of concentration fields, point source locations, and concentration gradients.To demonstrate the use and interpretations of the data provided by this method, the results of two mine site case studies are presented that will discuss: (1) Dewatering problems; (2) Mining recharge areas; (3) Mining coal overlain by an acid overburden; and (4) The impact of prior surface

ISSN:0017-467X    

DOI:10.1111/j.1745-6584.1981.tb03517.x

出版商:Blackwell Publishing Ltd    

年代:1981

数据来源: WILEY

摘要:

ABSTRACTAs a result of anthropogenic discharges of ground water far exceeding natural recharge, the Costa de Hermosillo aquifer is being actively intruded by salt water. Because this aquifer is utilized as the sole source of irrigation water for one of Mexico's principal agricultural districts, the application of any future management scheme to control this intrusion must be closely evaluated prior to implementation. A hydrologic and water quality simulation model is applied to the Costa de Hermosillo aquifer to assess the areal and temporal variations in head, velocity, and concentration as a result of changes in the present discharge distribution. The known hydrologic conditions are reproduced as a means of calibrating the model. Only qualitative statements on the future behavior of the aquifer are possible due to the uncertainty of the magnitude of various aquifer parameters and initial conditions. The model employed in this study is found to be a useful technique for the analysis of the effects of the proposed pumping stresses.

ISSN:0017-467X    

DOI:10.1111/j.1745-6584.1981.tb03518.x

出版商:Blackwell Publishing Ltd    

年代:1981

数据来源: WILEY

摘要:

ABSTRACTA digital model of a buried channel aquifer contaminated by hydrocarbons is used to evaluate development alternatives. The response to ground‐water pumping is critical because the hydrocarbons cause taste and odor problems. The source of contamination is an abandoned pit used to dispose of coal tar residues from an old coal‐gas plant. The hydrocarbon residues overflowed the pit, migrated a short distance and seeped into flood plain soils. The downward movement of the hydrocarbons stopped at the water table but some dissolved into the ground water. Three general approaches taken to evaluate management alternatives include: (1) regulation of pumping of the city wells and of drawdown, and recovery periods are considered and the model stressed with various pumping rates and times; (2) construction of a pumping trough barrier is considered and a hypothetical control well is simulated; (3) new well field developments in various locations are considered. Results suggest that there is no way to prevent movement of contaminants to the well field. The only feasible solution is the removal of coal tar residues from the source area and construction of a pumping trough barr

ISSN:0017-467X    

DOI:10.1111/j.1745-6584.1981.tb03519.x

出版商:Blackwell Publishing Ltd    

年代:1981

数据来源: WILEY

ISSN:0017-467X    

DOI:10.1111/j.1745-6584.1981.tb03522.x

出版商:Blackwell Publishing Ltd    

年代:1981

数据来源: WILEY