ISSN:0017-467X    

DOI:10.1111/j.1745-6584.1987.tb02868.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

ABSTRACTAn inverse relationship exists between the longitudinal electrical conductance (S) and the leakance (I.) of sediments between a bedrock aquifer and a surface‐water body. The empirical relationship for western Lake Michigan, first reported by Bradbury and Taylor (1984), has been refined after additional measurements. Leakance can now be predicted from longitudinal conductance with 95% confidence to within ±½ order of magnitude. Evidence is also presented that sediment samples collected by coring give erroneously low values for hydraulic conductivity and leaka

ISSN:0017-467X    

DOI:10.1111/j.1745-6584.1987.tb02869.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

ABSTRACTA simulation model was used in conjunction with linear and nonlinear programming to examine the effects of various management choices on the optimal allocation of imported water for artificial ground‐water recharge in the San Juan Valley of Central California. The simple linear objective of minimizing the sum of absolute values of drawdowns was of little value due to its dependence on hydro‐geologic properties. The choice between more complex linear and nonlinear objectives is shown to depend on the economic impacts of drawdowns one wishes to emphasize. Suitability of different drawdown reference levels was found to be a function of the specific form of the objective. Sensitivity analysis showed that the imported water could be recharged anywhere in the central portions of the cone of depression with minimal effect on the value of the objective function. Parametric variation of the total recharge rate illustrated the dependence of the various objective functions on the distribution of drawdown, discharge rates, and hydrogeologic properties. A preliminary analysis allowed the importance of conveyance cost to be demonstrated.This study has demonstrated that decisions regarding objective functions and their reference levels can be made only after careful consideration of basin characteristics and management go

ISSN:0017-467X    

DOI:10.1111/j.1745-6584.1987.tb02870.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

ABSTRACTA surface‐water/ground‐water interaction computer model was developed for the Grand Island, Nebraska municipal wellfield. This finite‐difference model, which is two‐dimensional in plan view, includes both quantity and quality components. The quantity component is a modified version of the Prickett‐Lonnquist model. Modifications account for the effects of the Plattc River channels, which flow through the modeled area, and adjust water levels at pumping wells to account for the difference between the well radius and the grid size. The quality component of the model calculates nitrate concentrations in pumping wells penetrating aquifers which arc vertically stratified with respect to nitrate. The model also estimates amounts of recharge from the river to the aquifer and the direction and velocity of movement of ground water in several nitrate‐contaminated areas adjacent to the wellfield. Nitrate is assumed to be a conservative pollutant, and nitrate transport is assumed to be solely due to advection. The model was calibrated using field data collected in 1984 and then verified with field data from two other independent events in 1978 and 1984. After calibration, the difference between measured and simulated heads at individual wells was less than one foot. Predicted nitrate concentrations in the pumping wells ranged from 0.07 to 0.40 mg/1 NO3‐N which is within the measured range of 0.00 to 0.58 mg/1 NO3‐N. River recharge predictions ranged from 176 to 200 cfs, whereas measured values were 168 to 232 cfs. The model was used to investigate the impacts of river diversions upstream on the quantity and quality of water in the wellfield. Simulation results indicate that zero‐flow conditions in the river cause drawdown to increase greatly, cause the nitrate concentration in the pumping wells to increase slightly, and cause the ground water in the nitrate‐contaminated area north of the wellfield to begin moving t

ISSN:0017-467X    

DOI:10.1111/j.1745-6584.1987.tb02871.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

ABSTRACTField procedures for collecting marine electromagnetic (EM) conductivity data were developed by the U.S. Geological Survey as part of a hydrogeologic investigation of the Delaware River shipping channel. Eighty miles of marine EM data collected along the border between Pennsylvania and New Jersey were used to help interpret results from high‐resolution, continuous seismic‐reflection surveys done in the Summer of 1984.Comparison of EM data with lithologic logs from river borings showed a direct relationship. EM conductivity of sand or bedrock ranged from 4 to 10 millimhos per meter (mmhos/m). Extensive clay beneath the shipping channel generally gave readings exceeding 20 mmhos/m. Conductivity readings over silts were almost always between these values (11 to 20 mmhos/m). This relation was used to help interpret the continuous seismic‐reflection

ISSN:0017-467X    

DOI:10.1111/j.1745-6584.1987.tb02872.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

ABSTRACTA detailed gravity survey of 295 points was conducted in Brimfield Township, Ohio to map buried bedrock topography with a higher degree of resolution than was possible by well data alone. The survey included a subset of 40 stations where both gravity and bedrock depth were determined. Partial correlation analysis allowed identification of a regional gravity trend, and multiple linear regression led to quantitative estimates of depth to bedrock throughout the surveyed area in a manner different from the standard method of gravity interpretation that employs models of different shapes, sizes, and density contrasts. Glacial sediments range in thickness from 10 to 150 feet, with the thickest portions generally over the axis of the buried valley. Some variations in predicted versus measured bedrock depth may be a function of variation in density of the glacial sediments or of topographic effects of the buried bedrock surface. The results of the analysis led to an improved estimate for the bedrock elevation and thickness of valley fill. The interpretation has implications with regard to the volume of glacial sediments in the area and their potential productivity as sources of ground water in the future.

ISSN:0017-467X    

DOI:10.1111/j.1745-6584.1987.tb02873.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

ABSTRACTThe emerging problem of contamination of ground‐water resources has created a need for information which can be supplied by properly designed ground‐water quality monitoring programs. The effective design of monitoring programs and the subsequent utilization of data obtained depends upon an understanding of the general statistical characteristics of ground‐water quality variables. In order to provide some background information on these characteristics, a synthesis of current literature and a statistical analysis of existing ground‐water quality data were conducted. Specifically, the purpose of the study was to determine whether ground‐water quality variables: (1) are normally distributed, (2) exhibit seasonal patterns, and (3) are correlated in time. The results of the investigation suggest that many ground‐water quality variables: are not normally distributed, but have skewed right distributions; can exhibit seasonal fluctuations of various shapes and magnitudes, especially in shallow or highly permeable aquifers; and can exhibit significant serial correlation when samples are collecte

ISSN:0017-467X    

DOI:10.1111/j.1745-6584.1987.tb02874.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

ABSTRACTThe benefits from ground‐water quality monitoring ultimately depend on the statistical methods used to analyze data. The methods must match both the information expectations of users and the characteristics of the water quality variables to which they are applied. The primary objective of regulatory ground‐water monitoring is detecting changes in quality. To select appropriate statistical tests for change, one must know whether the water quality variables of concern are seasonal, normally distributed, and serially dependent. This paper provides guidance in analyzing limited background data sets to determine these three characteristics.Recommended procedures to detect seasonality were pcriodograms, Student'st‐test, Mann‐Whitney test, analysis of variance, and Kruskal‐Wallis test. To test for normality, the skewness coefficient is recommended. To detect serial dependence, sample autocorrelation coefficients may be tested for sig

ISSN:0017-467X    

DOI:10.1111/j.1745-6584.1987.tb02875.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

ABSTRACTSalt‐water upconing describes the phenomenon where salt water is transported vertically upward under a well in response to pumpage in a fresh‐water aquifer underlain by salt water. Sharp interface methods have been used successfully to describe the physics of upconing. A finite‐element model is developed to simulate a sharp interface for determination of the steady‐state position of the interface and maximum permissible well discharges. The model developed is compared to previous published electric‐analog model results of Bennett and others (1968). Both methods are applied to a test case at Truro, Massachusetts, where maximum permissible discharges are determined by the finite‐element model to range from 0.47 to 1.05 cubic feet per second for the Test Site No.

ISSN:0017-467X    

DOI:10.1111/j.1745-6584.1987.tb02876.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

ABSTRACTMost of the solutions proposed by various workers to solve a nonequilibrium equation for the flow towards a nonpenetrating cavity well are based on the curve‐matching technique or an approximate straight‐line method. In this paper, another technique to solve an inverse problem has been proposed. This approach is simpler and more realistic since the element of human judgement is practically elimina

ISSN:0017-467X    

DOI:10.1111/j.1745-6584.1987.tb02877.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY