The same aquifer may be free, confined and semiconfined by sector and area of study. Potential distribution is found for two cases of unsteady flow in a finite leaky aquifer, where the. A pumping test is conducted at a fully penetrating well in a leaky confined aquifer which is overlain by an aquitard and an unconfined aquifer. Request pdf horizontal well hydraulics in leaky aquifers this paper presents a general study of horizontal well hydraulics for three aquifer. General well function for pumping from a confined, leaky.
An approximate differential equation to describe leaky. The basement beneath the aquifer is assumed to be impervious in most simulations, except those in section 4. Nondarcian flow to a well in a leaky aquifer using the. Groundwater response to tidal fluctuation in a leaky confined. This study explores the hydraulic response to pumping of leaky perched aquifers that receive continuous recharge. We explore whether distinct drawdown curves result that might reveal boundary effects or the position of the production well within the aquifer. Aquifertest is an easytouse software package for analyzing, interpreting and visualizing pumping and slug test data. Analysis of data from pumping tests in leaky aquifers.
An aquifers storage capacity depends on its pore space eg a sandy aquifer has more space than a fractured rock aquifer. 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. Field determination of the hydraulic properties of leaky. Analytical solutions for pumping and injection in leaky aquifer have been developed. Impact of aquitard storage on leaky aquifer pumping test. The water removed from storage in the aquifer and the water supplied by leakage the diameter of the well is very small, i.
Reviewers the editor greatly appreciates the contributions to this column from j. Model description leaky aquifer concept an ideal leaky aquifer model is depicted in figure1. Generally these solutions describe three theoretical aquifer types. 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.
A general well function for groundwater flow toward an extraction well with nonuniform radial flux along the screen and finitethickness skin, partially penetrating an unconfined, leaky boundary flux, or confined aquifer is derived via the laplace and generalized finite fourier transforms. Data were obtained chiefly from private consulting firms and from government agencies. 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. Education software downloads aquifertest professional by schlumberger network solutions and many more programs are available for instant and free download. We present a simple approach to assess stream depletion by groundwater pumping in aquifers with leakage from an underlying source bed. Analytical solutions which take account of aquitard storage are available, but there are few published examples of their successful application in practical situations. 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. The assumption of a constant water table will only be satisfied if the upper unconfined aquifer is recharged by an outside source. Analysis and evaluation of pumping test data hydrology. Geological survey open file report 02197, carson city, nevada.
Graphical methods are outlined for determining the coefficients of transmissibility storage, and leakage of an effectively infinite leaky artesian aquifer. Aquifer can be basically classified into three types. An unconfined aquifer groundwater level coincides with the surface and is in direct. Infinite extent aquifer pump test analysis software. 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. Combined effectiveness of demand management and managed aquifer recharge. Excel for hydrology listing and description nevada water. Test data can also be inserted from a windows text editor, spreadsheet, or database by cutting and pasting through the clipboard. 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.
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. This type of aquifer does not have a layer of waterproof material above them. In this paper a differential equation valid for intermediate and large values of time is proposed. Intermediate, similar to response in leaky aquifer. Three layers are considered producing layer, confining layer and aquifer layer which provides pressure support to main producing layer through a confining layer. Unlimited viewing of the articlechapter pdf and any associated supplements and figures. Nov 17, 2012 a comparison is made between the unsteady parallel fracture model using the double porosity approach and the anisotropic aquifer water table aquitard system. Threedimensional saturatedunsaturated simulations were. The procedure is based on the theory, developed by hantush and jacob, of the nonsteady flow toward a steadily discharging well. Horizontal well hydraulics in leaky aquifers request pdf. The value of s estimated from aquifer test represents confined storage coefficient. Related terms include aquitard, which is a bed of low permeability along an aquifer, and aquiclude or aquifuge. Environment canterbury actively compiles records of aquifer tests and well development. Designed by hydrogeologists for hydrogeologists, aquifertest delivers all the tools needed to accurately interpret data from all types of aquifers in all types of test conditions.
Hantush ms, jacob ce 1960 flow to an eccentric well in a leaky circular aquifer. The methods of analyses for tests in confined aquifers can be applied to analyze tests in. 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. Accurate definition of boundary and initial conditions is an essential part of conceptualizing and modeling groundwater flow systems. Stream depletion by groundwater pumping in leaky aquifers. 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.
Pdf determining the optimal pumping duration of transient. Aquifertest edition comparisoncompare editions licensing optionsstandalone softkey the software can only be installed on and run from one computer as the license file is tied to the mac address of that computer. Analysis and evaluation of pumping test data, revised second edition. Aquifer, confined, homogeneous, saturated, transmissivity, twodimensional. 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. The paper covers the basic theory of the aquifer type, the numerical solution of the leaky artesian. In analyzing a leaky aquifer for application in regional studies it is of great interest to have available simplified mathematical representations from which an analogical or digital model of the problem can be constructed.
Sometimes, fourth type of the aquifer is known as perched aquifer, but it is not the focus of any groundwater exploration. However, unreliable parameter values may be deduced since aquitard storage is ignored in classical leaky aquifer pumping test analysis. General well function for pumping from a confined, leaky, or. Pdf an analytical solution to a pumped leaky aquifer system.
Dimensional counterparts of b d and d were used by hantush 1964 and hunt 1999, respectively. Spreadsheets for the analysis of aquifertest and slug. Groundwater spreadsheets for solving groundwater flow and. Aquitards play an important role in the hydrology of multiple aquifer systems, and we.
Designed by hydrogeologists for hydrogeologists, aquifertest delivers all the tools. Method to characterize aquitards above leaky aquifers with water supply wells david w. Infinite extent supports distancedrawdown graphs for up to five observation wells. Jacob ce 1946 radial flow in a leaky artesian aquifer. Analysis of pumping tests in leaky confined aquifers. 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. Response of leaky aquifers to earth tides interpreted. Groundwater spreadsheets for solving groundwater flow. Method to characterize aquitards above leaky aquifers with.
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. Request pdf nondarcian flow to a well in a leaky aquifer using the forchheimer equation nondarcian flow to a well in a leaky aquifer was investigated using a finite difference method. An aquifer that is overlain or underlain by a semipervious layer aquitard through which vertical leakage takes place is called a leaky aquifer or semiconfined aquifer figure 3. From such layers or groundwater can be usefully extracted using a well. Zhan and park 2003 studied horizontal well hydraulics in a leaky confined aquifer, a leaky water table aquifer, and a leaky aquifer under a water reservoir. However, with careful use and by reducing sources of pollution, ground water can con. The solution assumes storage in leaky compressible aquitards and also accounts for partially penetrating wells hantush 1961a,b. Neuman and witherspoon 1969 derived a solution for flow to a pumping well in a confined twoaquifer system that accounts for leakage through a storative confining unit and drawdown in the unpumped aquifer.
Pdf estimation of the hydraulic parameters of leaky. Unconfined upper aquifers regularly fill and spill because they. 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. It is interest to quantify amount of pressure support provided by aquifer to main reservoir. The study of water flow in aquifers and the characterization of aquifers is.
This command will use drush make and other tools to construct a drupal site root, which will now be located in the build folder, or whatever folder is specified in aquifer. C characteristics of aquifers and their influence on potential for managed aquifer recharge adapted from dillon and jimenez 2008. Aquifertest professional with the ability to characterize your aquifer and analyze pumping and slug tests, aquifertest pro features all of the tools you need in one convenient groundwater data analysis program. A multilayered aquifer is a succession of leaky aquifers sandwiched between aquitards figure 2. Selected aquifer test data from 36 counties in eastern kansas were collected from numerous sources and publications in order to produce a documented compilation of aquifer tests in one report. Download aquifertest pro simulate, analyze and interpret the complex pumping and slug situations encountered in the hydrogeology field when dealing. A confined aquifer is an aquifer bound between two aquitards a formation of low permeability. Response of leaky aquifers to earth tides interpreted with. To create a leaky aquifer set the number of aquifers to one and check the box. The general analytical solution to a pumped axisymmetric, homogeneous, anisotropic aquifer, with leaky confining layers is obtained here. Stream depletion by groundwater pumping in leaky aquifers vitaly a. Ground water can be polluted by seepage through landfills, from septic tanks, from leaky underground fuel tanks, and sometimes from fertilizers or pesticides used on farms as shown at right.
Selected aquifertest data from 36 counties in eastern kansas were collected from numerous sources and publications in order to produce a documented compilation of aquifer tests in one report. The neuman and witherspoon solution differs from the solution by hantush and jacob 1955 which. In leaky aquifer steady state flow equilibrium case, the main well discharge, q, can be. The hydrogeological setting consists of a leaky aquifer that is hydraulically connected to a stream of shallow penetration. Sep 23, 2017 download aquifertest pro simulate, analyze and interpret the complex pumping and slug situations encountered in the hydrogeology field when dealing with aquifers. The study of water flow in aquifers and the characterization of aquifers is called hydrogeology.
The rate of leakage from the upper unconfined aquifer into the leaky aquifer is proportional to the hydraulic gradient across the aquitard. Significance of aquifer leakage to groundwater management. A confined aquifer is a completely saturated aquifer bounded above and below by aquicludes. The drawdown in the unpumped aquifer or in the aquitard, if there is no unpumped and for unsteadystate conditions. This is the hantushjacob solution for horizontal homogeneous leaky aquifer without storage in semipervious layer. A comparison is made between the unsteady parallel fracture model using the double porosity approach and the anisotropic aquiferwater table aquitard system. An aquifer is an underground layer of waterbearing permeable rock, rock fractures or unconsolidated materials gravel, sand, or silt. Evaluation of aquifer properties involves matching the hantush well function to waterlevel drawdown data collected during a pumping test aquifer test. Hydraulic properties determined included transmissivity, storage coefficient where observation well was available. Spreadsheet for leaky aquifer test analysis youtube.
Aug, 2011 this is the hantushjacob solution for horizontal homogeneous leaky aquifer without storage in semipervious layer. A multilayered aquifer is a succession of leaky aquifers sandwiched between. Unlike traditional aquifer test software, mlu is based on a single analytical solution technique for well flow that handles. Also, an analytical solution corresponding to an isolated well as a test. Spreadsheets for the analysis of aquifertest and slugtest data. Unconfined aquifers, anisotropic on the vertical plane. This type of aquifer does not have a layer of waterproof material above. 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. Download fulltext pdf estimation of the hydraulic parameters of leaky aquifers based on pumping tests and coupled simulationoptimization. The kansas geological survey is pursuing an effort to automate some of the more common methods of aquifer pumping. A hybrid optimization approach for parameter estimation of. Citeseerx document details isaac councill, lee giles, pradeep teregowda. A leaky aquifer model for hard rock aquifers springerlink.
Management of aquifer recharge and discharge processes. The presence of a moving water table in the weathered zone unconfined block, influenced by recharge from rainfall or other sources and leakage to the fracture zone, is discussed. Analysis of simulation 2 pumping from deep leaky confined aquifer using. An aquifer is an underground layer where the material contains water. Solved with an external dll estimates aquifer storage and vertical hydraulic conductivity and specific storage of adjacent confining units with a leaky aquifer solution that also provides another estimate of transmissivity moench, 1985. Aquifertest professional free version download for pc. When a well in a leaky aquifer is pumped, water is withdrawn not only from the aquifer, but also from the overlying and underlying layers. It was published in water resources research, 353, 747751, 1999.