Aquifer Pumping Research Articles

Mitigating negative water quality and quality externalities by joint mangement of adjacent aquifers

Groundwater basins are usually separated into aquifers that are hydrologically interrelated. This interrelation may take the form of water movement from one aquifer to another. When differ- entials in water quality exist, pumping from one of the aquifers can cause water movement that may be associated with degradation of its quality. A management policy that considers this interrelation may be preferable to an independent management of each aquifer. This paper develops a dynamic optimal control model to evaluate joint versus independent management. The optimal joint pumping management, in which two adjacent aquifers of different water qualities are interrelated, is analyzed and compared to independent aquifer pumping, and the situations where joint management is not required are identified. Policy implications are then derived and discussed. Finally, the theoretical model is applied to a case of interrelated aquifers in southern Israel. The empirical model identifies conditions (interest rate, agricultural fresh water supply rainfall recharge, price of surface water, drinking water quality standards) under which a joint policy is preferable. The empirical results confirm the theoretical ones.

Deformation‐Induced Changes in Hydraulic Head During Ground‐Water Withdrawal

AbstractGround‐water withdrawal from a confined or semiconfined aquifer causes three‐dimensional deformation in the pumped aquifer and in adjacent layers (overlying and underlying aquifers and aquitards). In response to the deformation, hydraulic head in the adjacent layers could rise or fall almost immediately after the start of pumping. This deformation‐induced effect is analyzed by a linear poroelasticity model using properties typical of unconsolidated sedimentary materials. Model simulations suggest that an adjacent layer undergoes horizontal compression and vertical extension when pumping begins. Hydraulic head initially drops in a region near the well and close to the pumped aquifer, but rises outside this region. Magnitude of head change varies from a few centimeters to more than 10 centimeters. Factors that influence the development of deformation‐induced effects includes matrix rigidity (shear modulus), the arrangement of aquifer and aquitards, their thicknesses, and proximity to land surface. Induced rise in hydraulic head is prominent in an aquitard that extends from land surface to a shallow pumped aquifer. Induced drop in hydraulic head is likely observed close to the well in an aquifer that is separated from the pumped aquifer by a relatively thin aquitard. Induced effects might last for hours in an aquifer, but could persist for many days in an aquitard. Induced effects are eventually dissipated by fluid flow from regions of higher head to regions of lower head, and by propagation of drawdown from the pumped aquifer into adjacent layers.

Estimating Hydraulic Conductivities in an Alluvial Basin from Sediment Facies Models

AbstractIt is not uncommon that hydraulic conductivity data are sparse in an area, and that information about subsurface sediment distributions are even more sparse or of poor quality. It is therefore desirable to have rational ways to estimate conductivity distributions for ground‐water flow modeling. Interpretations of the geologic history of a fault‐bounded sedimentary basin in south Santa Clara County, California, were used to estimate variations in sediment distribution and resulting relative hydraulic conductivities. Spatial sediment distributions were interpreted from the dominant infilling processes, using standard sedimentary facies models for alluvial fans and fluvial deposition. These sedimentary facies were categorized into interpreted hydrogeologic facies, which were then compared with measured hydraulic conductivity data obtained from scattered aquifer pumping tests in the basin. The comparison suggests that sedimentary facies models can provide a good basis for estimating the distribution of relative hydraulic conductivity. Further, the comparison provides a procedure for estimating hydraulic conductivities in areas where no measured values are available. This procedure provides a better basis for estimating hydraulic conductivities than methods which do not consider sedimentary processes.

Volumetric Leaky-Aquifer Theory and Type Straight Lines

A new method based on the depression cone volume concept is presented for the identification of hydraulic parameters of leaky aquifers with additional elastic storage release from the unpumped aquifer. The solution deals with the flow system by first considering the continuity equation based on the unpumped and pumped aquifers and constant pump discharges. The elastic storage coefficients are taken into account individually by relating them to the depression cone volumes. In addition, the unpumped aquifer flow is assumed to be transmitted to the pumped aquifer through the aquitard according to a pseudo steady-state flow law. The resulting first-order ordinary differential equation in terms of the depression cone volume is solved, leading to time-variant unpumped and pumped aquifer discharge expressions. The pumped aquifer is then considered as a confined aquifer with variable discharge to the well. The results are presented as type curves, which reduce to the Theis and Hantush solutions if the storage coefficient of the unpumped aquifer is neglected. The type-straight-line method is developed for hydraulic parameter estimations based on late time-drawdown data. The method is general and includes the De Glee steady-state and Jacob straight-line solutions as special cases. A dimensionless time-drawdown plot is proposed to determine whether the aquifer is leaky or not. Necessary steps in the application of the methodology are presented with actual field data.

In Situ Hydraulic Conductivity of Clay and Silty‐Clay Fluvial‐Deltaic Sediments, Texas Gulf Coast

AbstractTwo aquifer pumping tests (13 and 24 hours) and a tracer injection test were performed on shallow (7.5 m) clay and silty‐clay sediments of the fluvial‐deltaic Beaumont Formation from the U.S. Gulf Coast. The in situ horizontal hydraulic conductivity determined from these tests is found to be approximately 10−3 cm/sec. This value is one to three orders of magnitude larger than that of typical silts and clays, and two to four orders of magnitude larger than the vertical hydraulic conductivity measured on core in laboratory permeameter experiments. A uniformity of the drawdown curves from different observation wells strongly suggests that hydraulic conductivity is relatively homogeneous and isotropic in the horizontal plane at the scale of the test. This relatively large in situ horizontal hydraulic conductivity for these clay‐rich sediments is attributed to macroporosity rather than matrix porosity.

Damped least-squares inversion of confined aquifer pumping data based on singular value decomposition

An iterative method for calculating the transmissivity and storage coefficient from pumping test data for a confined aquifer is presented. The method optimizes the fit between the measured and the theoretical data (computed using the Theis equation) in the leastsquare sense. Unlike the existing schemes, this method employs the Levenberg-Marquardt method and the singular value decomposition technique resulting in a stable and rapidly convergent data inversion algorithm. The inverse procedure is initialized by an automatically created starting model derived using a novel technique that operates on the timederivative of the drawdown curve. An important feature of the algorithm is that all the computations are done in logarithmic space which effectively linearizes the pmblem. The proposed method has several advantages over the conventional iterative inversion algorithms because of the linearizing parameterizations at both the forward and inverse stages of the problem. Detailed derivations of the basic equations are provided to guide the potential users as well as applications to field data to demonstrate the usefulness of the proposed algorithm.

Nonsteady-State Drawdowns in Two Coupled Aquifers

A nonsteady coupled aquifer solution is developed in which transient and steady-state drawdowns can be calculated in a pumped aquifer and in an overlying unpumped aquifer that is separated from the pumped aquifer by a semipermeable confining bed. The water pumped is from artesian storage in the pumped aquifer and leakage through the overlying confining bed. This leakage is from storage in the water-table aquifer and a reduction in evapotranspiration due to a decline in the water table. As a simplifying assumption, storage in the confining bed is neglected. This solution is different from existing analytical solutions in that steady-state conditions can be reached because a source term representing the evapotranspiration reduction is included in the differential equations that are solved. A Laplace-space solution obtained for the differential equations and boundary conditions is inverted to the time domain using the Stehfest numerical algorithm. The resulting time-dependent solution is an efficient tool for making preliminary estimates and identifying additional data needs. Also, it can be used to verify solutions obtained using more complex analytical and numerical models.

Yield Model for Screening Surface- and Ground-Water Development

An optimization model is developed for selecting between candidate surface-water reservoirs and ground-water development. The model may be used to perform a preliminary screening of alternatives for water-supply development, and to identify storage capacities at reservoir sites, as well as aquifer pumping at candidate locations. A hybrid simulation-optimization strategy is used to consider monthly operation of the reservoir and aquifer system using historical or synthetic hydrologic data. A modified sequent peak algorithm is used for reservoir sizing, and a unit response matrix approach is used to model the ground-water subsystem. A target aggregate firm yield from the surface water–ground water system may be specified. Decisions on the failure of firm yield at each reservoir site during a critical period for streamflow, with a corresponding increase in ground-water pumping such that the system firm yield is maintained are considered. Example applications with data from the Jordan River basin in Utah demonstrate the utility of the model relative to a disjunctive analysis of surface water–ground water development.

Large‐Scale Aquitard Consolidation Near Mexico City

AbstractThe extensive lacustrine Chalco Plain in the southeastern part of Mexico City is underlain by an aquitard up to 300 m thick composed of a layered sequence of very porous (80‐90%) fine‐grained, organic‐rich Quaternary deposits, with thin horizontal interbeds of volcanic sand (“Capas Duras”). The aquitard overlies a thick sequence of alluvial‐pyroclastic sediments which form a highly productive regional aquifer. The Chalco Plain was a shallow lake until the 1940s when it was drained for agricultural use and human habitation. Historic information indicates that the Chalco Plain was an area of ground‐water discharge prior to the onset of heavy ground‐water extraction from the semiconfined aquifer. Due to aquifer pumping, however, the hydraulic gradient has reversed throughout the full thickness of the aquitard in areas where the aquitard is thin (< 100m), and recharging conditions now prevail. Where the aquitard is thick, the hydraulic head data show a progressive decline with time even though the hydraulic gradient still indicates upward flow in at least the upper part of the lacustrine sequence. Between the early 1960s, when major ground‐water extraction began beyond the periphery of the aquitard, and the onset in 1982 of heavy pumping from aquifers beneath the aquitard, the land surface subsided approximately 3 m. An additional subsidence of 2 m occurred between 1984 and 1989, causing a shallow lake to form and gradually expand. If the present rate of ground‐water withdrawal from the Chalco Basin continues, total land subsidence in the middle of the plain will probably continue to a rate of about 0.4 m per year for many years, and could eventually reach a total subsidence of tens of meters in the thickest part of the Chalco Plain. Pore water in much of the aquitard is saline; however, release of salts and other chemical constituents to the underlying aquifer has not yet significantly impaired the aquifer water quality. A better understanding of the behavior of the aquitard under the influence of aquifer pumping is needed to assist in long‐term management of ground water and land use in the Chalco Plain.

The Significance of the Extent of Recovery in Interpreting Aquifer Pumping Test Data from Large Diameter Wells

AbstractTo estimate aquifer parameters from pumping test data obtained from large diameter wells, one must consider the recovery data. This is particularly important for low permeability formations. Observations on the recovery should be continued to the maximum possible extent for an accurate estimation of these parameters. Analysis of data from a few representative case studies for granitic and basaltic rocks are presented here to establish a criterion to decide how long observations should be taken during recovery in the well.

A comparison of linear regression with Clark's Method for estimating barometric efficiency of confined aquifers

An estimate of barometric efficiency, often necessary for aquifer pump test interpretation, is difficult to obtain when there is a trend in water levels over time. Ordinary least squares (OLS) regression methods can be used to determine both the barometric efficiency and a trend function when the form of the trend is known. Clark's (1967) procedure, which does not require specification of the trend functional form, is shown to provide an unbiased and consistent estimate of barometric efficiency. OLS is only advantageous for a short data record providing the form of the trend is known. Clark's method may still be used with short data records with a linear trend when augmented by a recursive correction procedure. Both methods work best with constant barometric efficiency and rapid aquifer‐borehole water level equilibration.

OPTIMIZING THE PROBABILITIES OF WATER YIELD FOR THE RIDAURA AQUIFER (SPAIN)

ABSTRACT: Aquifer pumping represents, in many geographical locations, an alternative and/or a complementary source of water to surface water supplies. Several Catalonian coastal towns in the northeastern corner of Spain are in this situation. Also, since pumped water is used to supply drinking water, the main purpose in managing these water resources is to supply, no matter the cost, the amount needed at every moment. In other words, the managers of these aquifers attempt to optimize firm water yield. If we think of these aquifers as underground reservoirs with fixed storage capacity, most of the techniques which are applied to surface reservoirs can be implemented. In this paper we use a Stochastic Dynamic Programming model to optimize the yield from the aquifer of the Ridaura River. The objective function in this model was chosen with the aim of maximizing the reliability of the target yields in each of four seasons.

Groundwater flow and solute transport in fractured lacustrine clay near Mexico City : Water Resour ResV27, N9, Sept 1991, P2187–2201

A network of piezometers was installed in a surficial lacustrine clay aquitard overlying a thin saline water aquifer of volcanoclastic origin at a study site near Mexico City in the Basin of Mexico. The aquifer is underlain by additional lacustrine sediments which in turn overlie a thick regional freshwater aquifer. The regional aquifer provides approximately 70% of the water supply for 20 million people in the Basin of Mexico. In the study area, major ions, oxygen 18, and deuterium in the pore water of the surficial aquitard exhibit large variations with depth. The nature of these variations suggests that the saline pore water is being displaced downward by infiltrating meteoric water. The infiltration has been induced by strong downward hydraulic gradients imposed two to three decades ago when heavy aquifer pumping of the thin saline water aquifer began. One-dimensional analytical models representing solute transport in both fractured and unfractured porous media were used to simulate the geochemical profiles in the surficial aquitard. The fractured porous medium model, using a realistic mean hydraulic gradient and fracture spacing (1.5 m) and small but significant fracture aperture (30 μm) provide nearly an exact match to the field data. From this we infer that, because of vertical fractures, there is a much greater potential for downward leakage of water and contaminants through the Mexico City clay into underlying aquifers than has been previously thought.

Evaluating Hydrologic Parameters with Geophysical Techniques to Aid in the Design and Siting of Aquifer Pump Tests

Evaluating Hydrologic Parameters with Geophysical Techniques to Aid in the Design and Siting of Aquifer Pump Tests

Policies for water resource management in semiarid regions

Many of the freshwater problems of the 21st century will arise from increasing demands for water generated by rapid population growth, urbanization, industrialization and irrigation needed to satisfy the additional demand for food. The increased demand for water is being exacerbated by the excessive pumping of groundwater aquifers, some of which hold ancient or fossil’ water, and by the deteriorating quality of both surface and groundwater supplies. When it comes to the role and the fate of water resources in semiarid environments, despite the many differences socially, politically, culturally and economically among regions around the globe, many similarities actually exist. This article will examine in some detail how these issues manifest themselves in three geographic regions: the Western USA, especially the Central Valley of California; northwest Mexico, especially the Comarca Lagunera and Costa de Hermosillo; and the Aral Sea region of the Central Asian Republics of the Soviet Union. These case studi...

Genesis and continuity of quaternary sand and gravel in glacigenic sediment at a proposed low-level radioactive waste disposal site in east-central Illinois

The Illinois Department of Nuclear Safety has characterized the Martinsville Alternative Site (MAS) for a proposed low-level radioactive waste disposal facility. The MAS is located in east-central Illinois approximately 1.6 km (1 mi) north of the city of Martinsville. Geologic investigation of the 5.5-km2 (1380-acre) site revealed a sequence of chiefly Illinoian glacigenic sediments from 6 to 60 m (20–200 ft) thick overlying two major bedrock valleys carved in Pennsylvanian strata. Relatively permeable buried units include basal, preglacial alluvium; a complex of intraglacial and subglacial sediment; englacial deposits; and supraglacial fluvial deposits. Postglacial alluvium underlies stream valleys on and adjacent to the site. In most areas, the buried sand units are confined by low-permeability till, lacustrine sediment, colluvium, and loess. The distribution and thickness of the most extensive and continuous buried sand units have been modified considerably by subglacial erosion, and their distributions have been influenced by the buried bedrock valleys. The most continuous of the various sand units were deposited as preglacial and postglacial alluvium and are the uppermost and lowermost stratigraphic units at the alternative site. Sand units that were deposited in englacial or ice-marginal environments are less continuous. Aquifer pumping tests, potentiometric head data, and groundwater geochemistry analyses indicate minimal interaction of groundwater across localized interconnections of the permeable units.

Groundwater Flow and Solute Transport in Fractured Lacustrine Clay Near Mexico City

A network of piezometers was installed in a surficial lacustrine clay aquitard overlying a thin saline water aquifer of volcanoclastic origin at a study site near Mexico City in the Basin of Mexico. The aquifer is underlain by additional lacustrine sediments which in turn overlie a thick regional freshwater aquifer. The regional aquifer provides approximately 70% of the water supply for 20 million people in the Basin of Mexico. In the study area, major ions, oxygen 18, and deuterium in the pore water of the surficial aquitard exhibit large variations with depth. The nature of these variations suggests that the saline pore water is being displaced downward by infiltrating meteoric water. The infiltration has been induced by strong downward hydraulic gradients imposed two to three decades ago when heavy aquifer pumping of the thin saline water aquifer began. One‐dimensional analytical models representing solute transport in both fractured and unfractured porous media were used to simulate the geochemical profiles in the surficial aquitard. The fractured porous medium model, using a realistic mean hydraulic gradient and fracture spacing (1.5 m) and small but significant fracture aperture (30 μm) provide nearly an exact match to the field data. From this we infer that, because of vertical fractures, there is a much greater potential for downward leakage of water and contaminants through the Mexico City clay into underlying aquifers than has been previously thought.

Coupling versus uncoupling in soil consolidation

AbstractCoupling and uncoupling between the equilibrium and mass balance equations in soil consolidation problems in investigated in detail. A procedure for judging the strength of coupling is indicated. In the applications, particular emphasis is given to subsidence problems where the coupled nature of the problem is still sometimes questioned. It is shown that even in the case of a single pumped aquifer most situations are coupled.

The nature and management of saprolite aquifers in the wheatbelt of western Australia

AbstractRegional weathered‐zone goundwaters in the southern part of Western Australia are primarily stored in a granular saprolite aquifer derived from the isovolumetric weathering of granitic and gneissic rocks. Recent drilling has confirmed the existence of permeable materials capable of yielding groundwater of a suitable quality for livestock. Development of supplies of 10 to 250 kl d−1 is realisic and would complement local livestock, domestic and Government water supply systems. Wheatbelt aquifers currently supply 18 to 25 per cent of all water used for livestock in the agricultural areas of the southern part of Western Australia, although less than 1 per cent of the available resource is being utilized. Unused groundwater, artificially recharged by water‐use inefficiencies of agricultural development, provides both a potential resource and a cause of soil and water quality deterioration.Groundwater pumping may provide one method of aquifer control to mitigate the influence of secondary salinization. Pumping the low transmissivity Wheatbelt aquifers provides a means to lower water‐tables and limit the volume of groundwater reaching saline discharge areas at low points in the landscape. Unlike aquifer pumping systems developed in saline discharge areas, extraction systems in groundwater recharge areas, or in saline areas where groundwaters are of a suitable quality for agricultural use, can be used to mitigate salinity. The volume of groundwater available in southwestern Western Australia usually exceeds livestock requirements, to maintain low water‐tables, the water has either to be pumped to suitable drainage systems or alternative uses must be sought.

Interpreting recovery data from pumping tests

Abstract The shape of hydrographs of the recovery of well water levels for pumping tests in confined aquifers is shown to depend on well storage. This demonstration suggests that the standard method of interpretation of such recovery curves, as described in Todd, will not give accurate values unless the time after start of recovery is greater than about 25 R c 2 / T (see text for notation). Further, it is also demonstrated that if a leaky (low permeability) layer lies above or below the pumped aquifer the recovery curves can be modified significantly and are liable to misinterpretation.