Mathematical derivations of semianalytical solutions for pumpinginduced drawdown and stream depletion in a leaky aquifer system xiaoyong zhan and james j. A multilayered aquifer is a succession of leaky aquifers sandwiched between aquitards figure 2. Evaluation of aquifer properties involves matching the hantush well function to waterlevel drawdown data collected during a pumping test aquifer test. The pressure of the water in confined aquifers is usually higher than atmospheric pressure, which is why when a well is bored into the aquifer the water rises up the well tube, to a level higher than the aquifer figure 2. Commonly used analytical methods for assessing the effects of recharge and withdrawal on the groundwater flow system are based on an idealistic assumption that the aquifer s base is fully impervious. The aquifer educators consortium forms the bedrock of aquifer, bringing together more than 300 healthcare educators across disciplines. Recharge of this aquifer takes place through infiltration of precipitation from the ground surface. Neuman and witherspoon 1969 derived a solution for flow to a pumping well in a confined two aquifer system that accounts for leakage through a storative confining unit and drawdown in the unpumped aquifer. Aquifertest is an easytouse software package for analyzing, interpreting and visualizing pumping and slug test data. An unconfined, also known as water table aquifer, is one in which a water table exists.
The dupuit assumptions are valid, and hydraulic head h x,y,t. We present a simple approach to assess stream depletion by groundwater pumping in aquifers with leakage from an underlying source bed. The free aquifer is such in which there is free shallow water in contact with air and atmospheric pressure, so that its pressure is actually equal to the atmospheric pressure. Kansas geological survey 1930 constant avenue university of kansas lawrence, ks. Hantush and jacob step drawdown test solution for leaky.
Reviewers the editor greatly appreciates the contributions to this column from j. D602917 standard test method analytical procedure for determining hydraulic properties of a confined aquifer and a leaky confining bed with negligible storage by the hantushjacob method curvefitting method water level control wells transmissivity leaky confining bed. Aquifers and groundwater groundwater movement through aquifers is driven by differences in groundwater levels or pressure and is controlled by how porous the. Modelling interaquifer leakage associated with well. The additional water may be derived from storage of the aquitard and adjacent unpumped aquifers. Groundwater spreadsheets for solving groundwater flow and. Tables of the leaky aquifer well function western waters. Mathematical derivations of semianalytical solutions for. From these measurements the aquifer or well hydraulic properties can be evaluated.
Image files were generated from the original document and were converted to pdf files. Layers of impermeable material are both above and below the aquifer, causing it to be under pressure so that when the aquifer is penetrated by a well, the water will rise above the top of the aquifer. In this chapter, groundwater flow equations have been presented in inhomogeneous anisotropic unconfined aquifer, inhomogeneous, isotropic unconfined aquifer, leaky unconfined aquifer. In particular, we investigate the following three specific effects. Geological survey open file report 02197, carson city, nevada. Unconfined upper aquifers regularly fill and spill because they. A watertableor unconfined aquifer is an aquifer whose. A leaky aquifer, also known as a semiconfined aquifer, is an aquifer whose upper and lower boundaries are aquitards, or one boundary is an aquitard and the other is an aquiclude. Lai and chehwu su college of engineering and applied science, university of wisconsinmilwaukee, milwaukee, wise. Field determination of the hydraulic properties of leaky multiple. An analytical solution for threedimensional 3d flow in the storative semiconfining layers of a leaky aquifer fully penetrated by a production well is developed in this article to provide a.
It will usually be obvious during the drilling process if a well will provide the volumes required for a domestic supply, without the need to carry out an aquifer test. Analysis and evaluation of pumping test data, revised second edition. Geological survey open file report 20081166 by howard w. This is the hantushjacob solution for horizontal homogeneous leaky aquifer without storage in semipervious layer.
Method to characterize aquitards above leaky aquifers with water supply wells david w. Spreadsheet for leaky aquifer test analysis youtube. Pdf modeling groundwater flow in unconfined aquifers. The well penetrates the entire thickness of the aquifer and thus receives water by the flow in the aquitard is vertical. The drawdown in the unpumped aquifer or in the aquitard, if there is no unpumped and for unsteadystate conditions. Linear flow into the sides of an excavation in a confined aquifer that is overlain by a leaky aquitard. Method to characterize aquitards above leaky aquifers with.
Drawdown patterns resulting from pumping wells in leaky perched aquifers by catherine j. But, as pumping continues, the watertable in the upper aquifer will drop because more and more of its water will be leaking through the aquitard into the pumped aquifer. Groundwater flows into aquifers as recharge and out as discharge. The procedure is based on the theory, developed by hantush and jacob, of the nonsteady flow toward a steadily discharging well from an infinite leaky aquifer. The aquifer test is accomplished by applying a known stress. Groundwater response to tidal fluctuations in a leaky. Radial flow in a leaky artesian aquifer jacob 1946 eos. If the overlying aquitard extends to the land surface, it may be.
Aquifertest pro tutorial aquifertest pro from schlumberger water services is the latest software technology for graphical analysis and reporting of pumping and slug test data. Moench open file report 98415a a product of the groundwater resources program marlborough, massachusetts 1998. The distance drawdown graphs provides quantitative estimates of aquifer transmissivity, radius of influence of the pumping test, and a visual indication of horizontal anisotropy in the aquifer. An aquifers storage capacity depends on its pore space eg a sandy aquifer has more space than a fractured rock aquifer. The pumping well penetrates only one the main aquifer.
Data can be directly entered in aquifertest via the keyboard, imported from a microsoft excel workbook file, or imported from any data logger file in ascii format. It is interest to quantify amount of pressure support provided by aquifer to main reservoir. Leaky aquifers q unpumped aquifer pumped aquifer aquitard b 2 k 2 s s2 b 1 k 1 s s1 b k s s subscript 1 pumped zone subscript 2 unpumped aquifer prime aquitard q pumping rate b thickness k hydraulic conductivity s s specific storage assume. Infinite extent supports distancedrawdown graphs for up to five observation wells. Estimation of aquifer properties and well loss by matching hantush and jacob 1955 typecurve solution to timedrawdown data from a stepdrawdown test assuming a leaky confined aquifer data from clark 1977. Hantush, 1960, the flows in aquifer and aquitard can be both vertical and horizontal. When such effects cannot be easily detected in the aquifer, the confining beds are called aquicludes, and the aquifer is termed slightly leaky neuman and witherspoon, 19681.
The rate of leakage from the upper unconfined aquifer into the leaky aquifer is proportional to the hydraulic gradient across the aquitard. On the use of analytical solutions to design pumping tests. The assumption of a constant water table will only be satisfied if the upper unconfined aquifer is recharged by an outside. Request pdf horizontal well hydraulics in leaky aquifers this paper presents a general study of horizontal well hydraulics for three aquifer. The head in the adjacent aquifer is either constant throughout the pumpingtest period or varies over time due to pumping. Graphical methods are outlined for determining the coefficients of transmissibility storage, and leakage of an effectively infinite leaky artesian aquifer. An analytical solution of groundwater response to tidal. The pressure of the water in confined aquifers is usually higher than. Parameter estimation for leaky aquifers using the extended kalman. This type of aquifer does not have a layer of waterproof material above them. Field determination of the hydraulic properties of leaky multiple aquifer systems shlomo p. Groundwater discharge can feed lakes, streams, and wetlands and is part of the reason surface water bodies dont dry up between rains. Field determination of the hydraulic properties of leaky. Pumping from the aquifer induces leakage from the neighbouring aquitard units.
This exercise is written with the assumption that you have gone through the first exercise, and are familiar with the aquifertest interface this exercise is based on the pumping test data published in dawson and istok, p. An unconfined aquifer groundwater level coincides with the surface and is in direct. A confined aquifer is an aquifer below the land surface that is saturated with water. About aquifer formerly medu your trusted source for. Potential distribution is found for two cases of unsteady flow in a finite leaky aquifer, where the boundary condition at the contour of influence is time dependent and where the initial condition is one of different head in the main aquifer and in the semiconfining and quasi. Astm d6029 17 standard test method analytical procedure. Stream depletion by groundwater pumping in leaky aquifers. Analytical solutions for the preliminary estimation of. Journal o hydrology, 22 19i4 333345 northholland publishing company, amsterdam printed in the netherla,lds nonsteady flow to a large well in a leaky aquifer robert y. Aquitards play an important role in the hydrology of multiple aquifer systems, and we. The storage of the aquitards can be taken into account.
A complex of watersaturated rocks, consisting of aquifers separated by aquitards lowpermeability layers, is considered in this chapter fig. Pdf associated with power spectrum was also estimated. Nonsteady flow to a large well in a leaky aquifer sciencedirect. During early time of pumpage, water comes out of storage from the pumped aquifer and the leaky confining unit. Horizontal well hydraulics in leaky aquifers request pdf. Pdf stream depletion by groundwater pumping in leaky aquifers. Confined aquifer an aquifer with upper andor lower boundaries as an aquitard, where the water level in the aquifer extends above the aquifer top and is represented by a pressure head. Department of energy, nevada operations office under contract ey76c081253.
A confined aquifer is a completely saturated aquifer bounded above and below by aquicludes. Start using an aquifer course as a new staff member or new subscriber. The leaky aquifer is of uniform compressibility and of uniform transmissibility. The paper covers the basic theory of the aquifer type, the numerical solution of the leaky artesian.
An analytical model for flow induced by a constanthead. The rate at which groundwater levels drop when pumping occurs depends on how much water is stored and how quickly it moves through the aquifer. A multilayered aquifer is a succession of leaky aquifers sandwiched between. A well driven into it will indicate a static water level corresponding to the water table at that location. Vertical leakage, first from storage in the aquitard, then from the shallow aquifer. Aquifer simple english wikipedia, the free encyclopedia. A leaky aquifer, also known as a semiconfined aquifer, is a completely sat urated aquifer that is bounded below by an aquiclude and above by an aquitard. Goetz submitted in partial fulfillment of the requirements for the degree masters of science in hydrology new mexico institute of mining and technology socorro, new mexico december 2010. Aug, 2011 this is the hantushjacob solution for horizontal homogeneous leaky aquifer without storage in semipervious layer. Analytical solutions and computer programs for hydraulic. Spreadsheets for the analysis of aquifertest and slug. In this chapter, methods for evaluating aquifer test and singlewell tests conducted in confined, leaky, and unconfined aquifers are presented. Designed by hydrogeologists for hydrogeologists, aquifertest delivers all the tools. Groundwater recharge from lakes or open wetlands can have important implications for quantity and quality in leaky aquifers and lakes.
However, unreliable parameter values may be deduced since aquitard storage is ignored in classical leaky aquifer pumping test analysis. Confining layers overlying or underlying an aquifer are seldom completely impermeable. This paper discusses the results of work done on the leaky artesian aquifer as defined by hantush and jacob 1955. In addition, a stress pumping test can be performed to determine the transmissivity or degree of leakage between an unconfined aquifer and a deeper leaky confined aquifer. In this section, we use the 2d numerical model verified above to revisit the response of a leaky aquifer to earth tides and to investigate the limitations of the analytic solution in wang et al. Nonsteady radial flow in an infinite leaky aquifer, am. During pumping, the water table in the upper unconfined aquifer remain constant. Pdf estimation of the hydraulic parameters of leaky.
From such layers or groundwater can be usefully extracted using a well. Test data can also be inserted from a windows text editor, spreadsheet, or database by cutting and pasting through the clipboard. One approach to estimation is to conduct pumping tests and analyse the drawdowns using classical leaky aquifer theory. Strmdepl08an extended version of strmdepl with additional analytical solutions to calculate streamflow depletion by nearby pumping wells u. That can be less solid material like sand, gravel, clay or silt, but it can be rock as well, as long as the rock allows water to get in that means that it is waterbearing.
Analytical solutions and computer programs for hydraulic interaction of stream aquifer systems by paul m. Although application of the methodology appears as rather limited but it provides a scientific contribution and extension of leaky aquifer theory towards nonlinear. Response of leaky aquifers to earth tides interpreted with. Discover bestpractices and new ideas for integrating aquifer into your course or curriculum. The water removed from storage in the aquifer and the water supplied by leakage the diameter of the well is very small, i. Model description leaky aquifer concept an ideal leaky aquifer model is depicted in figure1. When a well in a leaky aquifer is pumped, water is withdrawn not only from the. The hydrogeological setting consists of a leaky aquifer that is hydraulically connected to a stream of shallow penetration. Analysis of data from pumping tests in leaky aquifers. Parameter estimation for leaky aquifers using the extended. Aquifer is home to a thriving, collaborative community of healthcare education leaders deeply committed to driving innovation in teaching and learning. It was published in water resources research, 353, 747751, 1999. For the leaky aquifer, the measurement equation was a truncated form of hantush and jacobs well function 1955, which was suitable for small leakage coef. Revisit the tidal response of a leaky aquifer with numerical simulation.
Impact of aquitard storage on leaky aquifer pumping test. The solution assumes storage in leaky compressible aquitards and also accounts for partially penetrating wells hantush 1961a,b. Aquifer, confined, homogeneous, saturated, transmissivity, twodimensional. This powerful yet easytouse program has everything you need to quickly calculate the hydraulic properties of your aquifer. Three layers are considered producing layer, confining layer and aquifer layer which provides pressure support to main producing layer through a confining layer. Leaky aquifers provide protected drinking water since the aquifer is overlain by an aquitard, and this study develops a method to estimate hydraulic properties of the latter deposit. Threedimensional flow in the storative semiconfining. The wellflow equations presented in this manual are based on several assumptions, one. The hydrogeological setting consists of a leaky aquifer that.
Conventional methods of analyzing leaky aquifers usually rely on drawdown data from the pumped aquifer alone. The educator guides are ideal for educators who are looking to. Groundwater response to tidal fluctuation in a leaky confined. Tight aquifers in which water levels have dropped significantly due to overdrafting are good candidates for asr because there has been storage room created to. Pdf theory of multiple leaky aquifers ismael herrera n. In addition, practical application of the general solution for the constant. Stream depletion by groundwater pumping in leaky aquifers vitaly a. Infinite extent aquifer pump test analysis software. Steady pumping, supply well shutdowns, and slug tests generate data in adjacent monitoring well clusters that characterize the aquitard. Lamesa abstract leaky aquifers provide protected drinking water since the aquifer is overlain by an aquitard, and this study develops a method to estimate hydraulic properties of the latter deposit. Aquifers educator guides are your complete guide to usingand making the most ofaquifer courses in your program. Witherspoon department of civil engineering, university of california berkeley, california 94720 abstract.
Linear flow into the sides of an excavation in a confined aquifer. Training resources page 1 of 6 usgs training resources for groundwater hydrology resources listed include reports, videotapes, and selfstudy manuals. What is the difference between a confined and an unconfined. An aquifer is an underground layer where the material contains water. Groundwater spreadsheets for solving groundwater flow. The study of water flow in aquifers and the characterization of aquifers is. On the use of analytical solutions to design pumping tests in leaky aquifers connected to a stream steen christensen a, vitaly a. Estimation of the hydraulic parameters of leaky aquifers based on pumping tests and coupled simulationoptimization. Therefore, the leaky aquifer must be viewed as part of a.
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