ISSN:0017-467X    

DOI:10.1111/j.1745-6584.1985.tb01492.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

ABSTRACTExtensive caves have developed under canyons in the Trapper‐Medicine Lodge recharge area where ground‐water flow rates became maximized within the Madison carbonates during Cenozoic time. The large flow rates resulted directly from the superposition of steep local gradients on the ground‐water circulation system as a consequence of the erosion of confining units in the region. The cave forming process in this area is gradient controlled, a conclusion that has possible applicability else

ISSN:0017-467X    

DOI:10.1111/j.1745-6584.1985.tb01493.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

ABSTRACTDug wells in the Deccan basalts of India can provide a means of determining the permeability of the unconfined aquifer within the weathered layer. The layered nature of this aquifer, together with its low permeability, produces a complicated ground‐water flow pattern around large‐diameter dug wells when they are pumped. A digital model, which successfully simulated the head distribution in and around a large‐diameter pumping well demonstrated that recovery, rather than drawdown, data from such tests are more suitable for ana

ISSN:0017-467X    

DOI:10.1111/j.1745-6584.1985.tb01494.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

ABSTRACTA distributed parameter ground‐water management model was developed using finite‐difference approximations of the governing partial differential equation for ground‐water flow in a confined aquifer. The resulting system of simultaneous equations was embedded in an optimization model, which used hydraulic heads and pumpages as unknown state variables and decision variables, respectively. The model was applied to several hypothetical examples of varying size and complexity and to one real‐world example, the Las Vegas Valley aquifer. The grid spacing, time increment, bounds placed on pumpage, and the number of constraints were found to affect not only the execution time, but also whether the model would execute at all.In order to accommodate long‐term management goals, a lumped transient model should be used which incorporates all time periods the model encompasses. Some objective functions, such as the maximization of the head, can be executed in a stepwise manner in which the final heads from the current period are used as the initial heads for the next period. The embedding technique proved useful for small management problems, but had numerical difficulties with the large real‐world problems of considerable heterogeneity. Unless the embedding technique can become computationally efficient and stable, it should be bypassed in favor of the response matr

ISSN:0017-467X    

DOI:10.1111/j.1745-6584.1985.tb01495.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

ABSTRACTBetween Salina and Enterprise, Kansas, the salinity of the Smoky Hill River increases sharply. As a result, the river downstream at various times exceeds the recommended drinking‐water‐quality standards for chloride. The Smoky Hill and Kansas Rivers are important sources of water for several population centers in eastern Kansas. Therefore, this problem has an impact on a significant part of the Kansas population. The source of the saline water is predominantly from ground‐water dissolution of the Hutchinson Salt Member of the Wellington Formation of Permian age. The dissolution of the salt has caused a north‐south trending collapsed zone called the Wellington aquifer to occur along the present eastern extent of the salt. A confining shale layer exists between the Smoky Hill alluvium and the Wellington aquifer in most areas. However, between New Cambria and Solomon, Kansas, the layer is thin and fractured, allowing the salt water to move up into the alluvium.The steady‐state model presented in this study indicates that the salt‐water layer of the alluvium in the Smoky Hill River valley should be in an unstable condition near the river. This indicates that unstable interface upconing should be a dominant mechanism for supplying salt water to the river system. The time‐varying model shows that the response of the chloride discharge to a flood event can be qualitatively explained by the unstable interface upconing mechanism. As the river stage rises, the salt‐water intrusion declines. As the river stage declines, the salt‐water intrusion increases beyond its normal value and subsides to the normal value over the period of a few months if no new flood events occur. During rising river stage, the river is supplying the ground‐water system, and the salt‐water intrusion or unstable upconing is shut off. During falling river stage, bank storage and perhaps an elevated water table cause the fresh ground‐water discharge to be greater than normal, which in turn causes greater than normal salt‐water intrusion. In addition, the time‐varying model shows that several years would elapse before significant benefit would be seen in the river system from a proposed Wellington

ISSN:0017-467X    

DOI:10.1111/j.1745-6584.1985.tb01496.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

ABSTRACTThis paper develops an analytical expression for contaminant transport from a finite source in a continuous flow regime. The model requires some numerical integration and its degree of accuracy for near‐field problems depends on discretization procedures applied to the source boundary. A second model for a continuous source is developed by extending a well‐known pulse model. This second model is particularly useful in that it permits the determination of several potential unknowns directly from a concentration distribution. These include the source concentration, source dimensions, the position of the center of mass which is the product of the seepage velocity and the time since the contaminant first entered the ground water, and up to three dispersivities for a three‐dimensional problem. As a demonstration of its utility, this second model is applied with reasonable success to a well‐defined field condition. A comparison of the two models indicates that, except for minor differences in the very near field, the results from each are virtually id

ISSN:0017-467X    

DOI:10.1111/j.1745-6584.1985.tb01497.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

ABSTRACTThe ground‐water flowmeter system, model 3OL, manufactured by K‐V Associates Inc., Falmouth, Massachusetts was tested under controlled laboratory conditions. The influence of slotted pipe schedule, slot orientation, backfill materials, endcap bags, isolated regions of high hydraulic conductivity, and channelization near the slotted pipe wall was measured. The physical concept of the flow‐meter in an ideal configuration was analyzed, and with the aid of an analytical model, the significance of the thermal and hydraulic characteristics of the aquifer and backfill materials is clarified. Results indicate that the basic instrument response is linear, consistent, and predictable qualitatively in a laboratory environment. Analysis and measurements show clearly that very small channelization around a slotted pipe casing or between the slotted pipe and the probe endcap can invalidate the instrument response. Additional potential complications arise due to unknown permeability contrasts between the aquifer matrix and the material used to backfill around the

ISSN:0017-467X    

DOI:10.1111/j.1745-6584.1985.tb01498.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

ABSTRACTIn response to the detection of contaminants in several municipal water supply wells in a northern New Jersey community, the New Jersey Department of Environmental Protection (NJDEP) undertook a detailed assessment of the movement of volatile organics through the Brunswick fractured rock aquifer. Understanding the directional or anisotropic behavior of ground‐water flow within the aquifer proved to be a crucial factor for identification of the sources of contamination. Since the ground‐water flow occurs in a direction predominantly parallel to the strike of the aquifer, the resulting distribution of contaminants allowed the differentiation of two overlapping plumes, each over 4,000 feet in length and each emerging from discrete adjacent sources.The investigations and subsequent cleanup agreements between the NJDEP and the responsible parties allowed savings of several million dollars for the U.S. EPA's Super‐fund Program which otherwise would have been used for cleanup of the site. The privately funded cleanup program includes treatment of the affected municipal wells and on‐site remedial actions designed to fully restore the aquifer within 1

ISSN:0017-467X    

DOI:10.1111/j.1745-6584.1985.tb01499.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

ABSTRACTEstimation of rates of contaminant movement at land treatment sites requires accurate measurements of water movement through the soil zone. A moisture balance method that employs the zero flux plane concept and several simplifying assumptions about saturated and unsaturated flow conditions gives reasonable estimates of evapotranspiration and percolation fluxes when applied to a land treatment site in central coastal California. The technique requires measurements of the saturated hydraulic conductivity of field soils as well as soil matric suction and moisture content at regular time intervals. Replicate monitoring clusters for matrix suction and moisture content are necessary in spatially variable soils but a detailed knowledge of the spatial variability of saturated hydraulic conductivity is not warranted.

ISSN:0017-467X    

DOI:10.1111/j.1745-6584.1985.tb01500.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

ABSTRACTAnalytical and numerical modeling procedures based on the hydrodynamic dispersion were used to analyze the salt‐water contamination problem in the Nakhon Luang aquifer underlying the City of Bangkok. A preliminary evaluation is performed for the approximate locations of the contaminating sources, and its rate and pattern of encroachment are predicted under different operating conditions in the future to assist in planning an efficient and economic monitoring network. The contaminating source is widespread and is located on the western side of the Chao Phraya River. With the present trend of pumping, the rate of encroachment is greatest from the northwest direction towards the main pumping center. The study indicates the advantage of performing one‐dimensional model analysis prior to attempting two‐dimensional regional analysis, particularly in cases where the initial chloride concentration distribution is un

ISSN:0017-467X    

DOI:10.1111/j.1745-6584.1985.tb01501.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY