ISSN:0017-467X    

DOI:10.1111/j.1745-6584.1986.tb00989.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY

摘要:

ABSTRACTRelatively little work has been done using streamflow data as a means of estimating hydrologic parameters such as transmissivity and storativity. An approach to this problem utilizing the physical insight offered by electric analog modeling techniques has been developed with streamflow data from two small drainage basins in northwest Virginia. Streamflow modeling has produced regional estimates of the ratio of transmissivity to storativity, and results from each region indicate this ratio to be larger than expected. This discrepancy is resolved by assuming that the drainage basins contain only a small percentage of permeable rock, and this assumption suggests a further use of the model to estimate the percent of permeable rock in a watershed. The analog approach presented here shows potential for further development using digital computer methods.

ISSN:0017-467X    

DOI:10.1111/j.1745-6584.1986.tb00990.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY

摘要:

ABSTRACTA method for determining a spatially distributed set of ground‐water withdrawals that maintains a regionally “optimized” potentiometric surface is presented. A goal‐programing approach, in its quadratic form, is used to minimize the sum of squares of differences between the optimized surface and a “target” potentiometric surface. Constraints on withdrawals and recharge, imposed through a two‐dimensional ground‐water flow equation, and bounds on drawdowns assure that the withdrawal strategy developed is realistic and physically feasible. Application is demonstrated using data from the Grand Prairie reg

ISSN:0017-467X    

DOI:10.1111/j.1745-6584.1986.tb00991.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY

摘要:

ABSTRACTInfluences of limestone on physical and chemical characteristics of Abrams Creek in Cades Cove, Great Smoky Mountains National Park, were investigated from February to July 1977. Infiltration of stream water into subsurface permeable limestone conduits caused reduced and intermittent surface flow within the middle reach of the Cove. At the downstream (west) edge of the Cove, inflowing waters characteristically warmed the stream in winter and cooled it in summer and increased stream conductivity, total hardness, and pH. Management activities in the Cove did not appear to appreciably affect the chemistry of the aquatic system downstream relative to the large effects of limestone substrate.

ISSN:0017-467X    

DOI:10.1111/j.1745-6584.1986.tb00992.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY

摘要:

ABSTRACTHydrogeologic studies commonly include the development, calibration, and application of a deterministic simulation model. To help assess the value of using such models to make predictions, a postaudit was conducted on a previously studied area in the Salt River and lower Santa Cruz River basins in central Arizona. A deterministic, distributed‐parameter model of the ground‐water system in these alluvial basins was calibrated by Anderson (1968) using about 40 years of data (1923–64). The calibrated model was then used to predict future water‐level changes during the next 10 years (1965–74). Examination of actual water‐level changes in 77 wells from 1965–74 indicates a poor correlation between observed and predicted water‐level changes. The differences have a mean of 73 ft that is, predicted declines consistently exceeded those observed and a standard deviation of 47 ft. The bias in the predicted water‐level change can be accounted for by the large error in the assumed total pumpage during the prediction period. However, the spatial distribution of errors in predicted water‐level change does not correlate with the spatial distribution of errors in pumpage. Consequently, the lack of precision probably is not related only to errors in assumed pumpage, but may indicate the presence of other sources of error in the model, such as the two‐dimensional representation of a three‐dimensional problem or the lack of consideration of land‐subsidence processes. This type of postaudit is a valuable method of verifying a model, and an evaluation of predictive errors can provide an increased understanding of the system and aid in assessing the value of undertaking devel

ISSN:0017-467X    

DOI:10.1111/j.1745-6584.1986.tb00993.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY

摘要:

ABSTRACTFindings from a detailed hydrogeologic study of a Micronesian atoll island are combined with published descriptions of the hydrogeology of other atoll islands. The purpose is to propose a conceptual model which describes how the occurrence and flow of ground water in atoll islands are related to the underlying geologic framework. The study island is Deke, a small, uninhabited island on Pingelap Atoll in the Eastern Caroline Islands.Integrated studies on Deke of surface geology and physiography, water levels and their variation, surface geophysics (seismic refraction and resistivity), and subsurface core samples indicate a hydrogeologic system that is more complex than would ordinarily be expected for a small and, at first glance, uncomplicated island. Of utmost importance to the occurrence and flow of ground water is the fact that the island straddles the lagoonward edge of the very firmly indurated reef‐flat plate. This plate is a hard, impermeable substrate beneath the northern portion (ocean side) of the island, occurs at sea level, and is underlain by unconsolidated or loosely cemented sediments. Study results indicate that this reef‐flat plate acts as a confining bed along the ocean side of the lens; elsewhere the lens is unconfined, receives recharge directly, and forms a thicker fresh‐water nucleus.The conceptual model of atoll‐island hydrogeology involves a dual aquifer system: (1) an aquifer of mostly unconsolidated Holocene sediments resting on (2) a once emergent and now very permeable Pleistocene limestone platform. The Holocene aquifer, which is where the island lens occurs, is heterogeneous with respect to its hydraulic properties and is confined in part of the island and unconfined elsewhere, with the location of the two regions depending on where the island sits relative to the pinchout of the reef‐flat plate. In the unconfined region, there is a hydrologically‐important central depression, where low lying sediments are enclosed by ocean‐derived washover fans and a lagoon‐bordering dune. This area is a likely ground‐water sink due to direct evapotranspiration during the dry season. Accordingly, the model includes two flow patterns: a wet‐season pattern radiating outward from the unconfined lagoon‐side of the island, and a dry‐season pattern that includes a superimposed area of centripetal flow at

ISSN:0017-467X    

DOI:10.1111/j.1745-6584.1986.tb00994.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY

摘要:

ABSTRACTA stream‐aquifer simulation model was developed to evaluate different conjunctive use management strategies in the South Platte River in Colorado. A component of this model simulates the allocation of surface and ground water for agricultural use. The water law based on the doctrine of prior appropriation provides the basic framework for water allocation in the study area. The physical sequence in which the river diversions are located along the river is different from the sequence in which the water has to be allocated according to the priority of rights. An algorithm is designed to allocate the river flows computed by the physical simulation component of the model to the appropriators according to the water rights and other imposed criteria as specified by the conjunctive management scheme under study. The algorithm is demonstrated on a management problem involving the evaluation of a streamflow augmentation scheme in the study reac

ISSN:0017-467X    

DOI:10.1111/j.1745-6584.1986.tb00995.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY

摘要:

ABSTRACTMapping of ground‐water spatial data is an important part of any geohydrologic investigation. There are three main classes of interpolators used for such mappings. The first group include simple estimators which are commonly used in practice. The second group are least‐squares estimators which are basically fitting processes. The last category are Gauss‐Markov estimators, such as kriging, which beside being exact interpolators, produce measures for the accuracy of the estimated field. These estimators are compared theoretically and numerically. These studies show that kriging yields relatively robust estimates. However, its suggested statistical inference method may not always produce robust estimates of the covariance function parameters. Simple estimators produce unstable results, while least‐squares methods ignore local variations by fitting a single polynomial function over the whole field. For this study, water‐table data from northwest Kansas

ISSN:0017-467X    

DOI:10.1111/j.1745-6584.1986.tb00996.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY

摘要:

ABSTRACTA method has been developed by which the slope between any two successive data points on a time‐drawdown plot can be used for determining aquifer parameters in nonleaky and leaky aquifers. The method yields values of transmissivity and storage coefficient which are in good agreement with the results of the classically known techniques. The method of slope analysis offers several advantages in its use. These advantages include the following: Changes in values for the aquifer parameters that might occur during a pumping test can be identified. Confidence limits can be calculated for average values of aquifer parameters. The method yields meaningful aquifer parameter estimates even for short duration pumping tests. Subjective interpretation of the data is minimize

ISSN:0017-467X    

DOI:10.1111/j.1745-6584.1986.tb00997.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY

摘要:

ABSTRACTThe equation for two‐dimensional, vertically averaged steady‐state flow to a finite‐length line sink, a semiempirical expression for the radius of influence, and the theory of superposition are used to predict the impacts of excavations on ground‐water flow patterns. The algorithm provides a rapid method for estimating the inflow to mine pits, and the impact of mines on the potentiometric surface. An accurate expression for the radius of influence is developed by comparison with analytical and finite‐difference model solutions. The algorithm is an accurate estimate of drawdowns at longer times, when the steady‐state approximation is

ISSN:0017-467X    

DOI:10.1111/j.1745-6584.1986.tb00998.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY